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					   POWER EVACUATION SYSTEM STUDY FOR
SELECTED HYDROPOWER PROJECTS IN WESTERN
                NEPAL




                    DISSERTATION
     Submitted in partial fulfillment of the requirements of
     Master of Engineering in Electrical Power Engineering




                   Manohar Shrestha




      Department of Electrical and Electronics Engineering
                   School of Engineering
                 Kathmandu University

                     December 2005
   POWER EVACUATION SYSTEM STUDY FOR
SELECTED HYDROPOWER PROJECTS IN WESTERN
                NEPAL




                    DISSERTATION
     Submitted in partial fulfillment of the requirements of
     Master of Engineering in Electrical Power Engineering



                              By:

                   Manohar Shrestha




                     Under supervision of:
                Mr. Surya Prasad Adhikari
                 Planning and Design Engineer
                    Engineering Department
                 Butwal Power Company Ltd.
                              and
                  Mr. Lalt Bickram Rana
                      Assistant Professor
      Department of Electrical and Electronics Engineering
                     School of Engineering
                   Kathmandu University




      Department of Electrical and Electronics Engineering
                   School of Engineering
                 Kathmandu University

                     December 2005
                   ACKNOWLEDGEMENT


I would like to express sincere and profound gratitude to our Project Supervisors

Mr. Surya Pd. Adhikari and Mr. Lalit B. Rana for helping me to complete this

project with valuable guidance whenever I faced problem during the course of

dissertation.

I would also like to express my hearty thanks to Dr. Bhupendra Bimal Chhetri,

HOD electronics and electrical department, KU, for providing necessary material

and uninterrupted access to computer lab for project work.

Special thanks go to Mr. D.D Joshi, M.D AutoCarto Pvt. Ltd. for providing relevant

data required for the study and Er. Kiroj Shrestha, Western Grid Office, NEA for

helping to get existing present data of Western Nepal from Western Central Office,

NEA.

At last, I am very much thankful to my classmates and colleagues whose sincere

efforts have inspired me to be with them in the pursuit of academic goals.
                                    ABSTRACT


Electricity Power Evacuation from small hydro power plant is emerging as challenge for

the entire entrepreneur who wishes to enter in the field of hydro power sector. The

increasing load demand and availability of power market around the clock in Nepal has

evoke many capitalist to invest in hydro power sector. This thesis studies the present and

will identify future power evacuation system performance in certain area of Lamjung

district from different power plants Khudi (KHP) 3.5 MW, Lower Nyadi (LNHP), 4.5 MW

and Lower Khudi (LKHP), 2 MW. The thesis studies existing and proposed power

evacuation system and carries out detail study of an existing transmission line and conduct

detail study of power evacuation systems from KHP, LNHP and LKHP. The thesis also

studies the performance of distribution system for Lamjung district.

       The methodology adopted for carrying out evacuation study is based on following:

         •   Collection of data regarding existing and proposed electrical system.

         •   Preparation of program/software for technical and financial analysis of

             evacuation system

         •   Identification of different transmission line alternatives and selection of best

             option.

         •   Study performance of evacuation sys tem.

         •   Study performance of distribution system.

For studying power evacuation system transmission capacity, available transmission

margin and transmission are taken into consideration. For distribution system performance

study computer programs are developed. Spreadsheet for calculation of transmission line

performance and Carl1.0 (Load flow software for radial distribution network) for studying

distribution feeders has been updated.
                        TABLE OF CONTENTS
GLOSSARY OF ABBREVIATIONS                                                      i
LIST OF FIGURES                                                               ii
LIST OF TABLES                                                               iii
CHAPTER 1                                                        INTRODUCTION
                                                                              1
 1.1  General                                                                 1
 1.2  Objective                                                               1
 1.3  Background                                                              2
 1.4  Performance standard for Grid                                           2
CHAPTER 2                  EXISTING ELECTRICAL SYSTEM IN STUDY AREA
                                                                              4
 2.1  Existing power plants in western Nepal                                  4
 2.2  Under Study Small Hydro Power Plant in Western Nepal                    4
 2.3  Existing Grid transmission system in western Nepal                      5
 2.4  Existing Electrical Network in Some District of Western Nepal.          6
CHAPTER 3                                                       METHODOLOGY
                                                                            11
 3.1  Data Collection                                                       11
 3.2  Transmission line alternative                                         12
 3.3  Available Transmission Capacity                                       13
 3.4  Transmission Margin                                                   13
 3.5  Performance of Transmission line                                      13
 3.6  Distribution system planning                                          13
 3.7  Spread Sheet Calculation for Conductor selection and Voltage [2]      14
 3.8  Carl 1.0                                                              18
 3.9  Netbas Simulation                                                     18
 3.10 Evacuation System for KHP, LNHP and LKHP.                             19
CHAPTER 4                                           RESULTS AND DISCUSSIONS
                                                                            20
 4.1  Existing System Result                                                20
 4.2  KHP Evacuation System                                                 25
 4.3  Results of LNHP Evacuation System                                     33
 4.4  KHP and LNHP Evacuation system                                        34
 4.5  System with KHP, LNHP and LKHP                                        41
 4.6  KHP, LNHP, LKHP and Chame substation                                  42
 4.7  Load flow analysis of four feeders of Udipur S/S                      43
CHAPTER 5                        CONCLUSION AND RECOMMENDATION
                                                             45
REFERENCES                                                   48



 APPENDICES
Appendix      A:   Transmission line Design Procedur e
Appendix      B:   Load Flow Analysis in Electric Power distribution
Appendix      C:   SLD of Existing Electrical Network
Appendix      D:   Spread Sheet Results
Appendix      E:   Netbas Results
Appendix      F:   Carl1.0 Results
Appendix      G:   List All Power source and Cost
               GLOSSARY OF ABBREVIATIONS

Abbreviation   Full-Form                                     First in Page
INPS           Integrated Nepal Power System
KHP            Khudi Hydro Power
LNHP           Lower Nyadi Hydro Power Plant
LKHP           Lower Khudi Hydro Power Plant
NEA            Nepal Electricity Authority                                 2
JHP            Jumdi Hydro Power                                           2
BPC            Butwal Power Company                                        2
DOED           Department of Electricity Department                        5
SHPP           Small Hydro Power Project                                   5
WI             Winrock International                                       5
VDC            Village Development Committee                               8
LEDCO          Lamjung Electricity Development Company                     9
ACSR           Aluminum Conductor with Steel Reinforcement                 9
USC            US Cent                                                    15
S/S            Substation                                                 21
KSw/S          Khudi Switching Station                                    26
USS            Udipur Substation                                          31
DuSS           Dumre Substation                                           31
AkSS           AnbuKhaireni                                               31
DaSS           Damauli Substation                                         31




                                                                      i
                       LIST OF FIGURES

Figure No.   Caption                                          Page
2.1          5 MVA 33/11 kV Udipur Substation                      10
3.1          Conductor optimization sheet using spreadsheet        17
4.1          Existing Electrical System of Lamjung District        20
4.2          Conductor selection for KHP evacuation                26
4.3          KHP evacuation system                                 27
4.4          Conductor optimization chart for LNHP only            34
4.5          Conductor and voltage chart for KHP and LNHP          36
4.6          KHP and LNHP evacuation system                        37
4.7          KHP, NHP and LKHP evacuation system                   42
4.8          Evacuation system with Chame load                     43




                                                              ii
                      LIST OF TABLES

Table No.   Caption                                                       Page
2.1         Small Hydro Power Plants of Western Nepal                        4
2.2         SHP projects (1-10 MW) in Western Nepal                          5
2.3         Existing 132 kV Transmission Line of Western Nepal               6
2.4         Feeder Status of 5 MVA, 33/11 kV Udipur S/S                     10
4.1         Full S/S load, Existing System                                  21
4.2         70% S/S load Existing System                                    21
4.3         50% S/S load Existing System                                    22
4.4         30% S/S load Existing System                                    22
4.5         10% S/S load Existing System                                    23
4.6         100% S/S load with 'Wolf' Existing System                       23
4.7         80% S/S load with 'Wolf' Existing System                        24
4.8         50% S/S load 'Wolf' Existing System                             24
4.9         Spread Sheet calculation for KHP evacuation system (0.9 km)     25
4.10        Spread Sheet calculation for KHP evacuation system (14.9km)     26
4.11        Full load, KHP evacuation System                                27
4.12        70% load, KHP evacuation System                                 28
4.13        50% load, KHP evacuation System                                 28
4.14        30% load KHP evacuation System                                  29
4.15        10% load KHP evacuation System                                  29
4.16        100% load with 'Wolf' KHP evacuation System                     29
4.17        50% load with 'Wolf' KHP evacuation System                      30
4.18        100% S/S load, effect in existing system with KHP               31
4.19        70% S/S load, effect in existing system with KHP                31
4.20        50% S/S load, effect in existing system with KHP                32
4.21        30% S/S load, effect in existing system with KHP                32
4.22        10% S/S load, effect in existing system with KHP                33
4.23        LNHP evacuation System                                          33
4.24        LNHP and KHP 33 kV transmission line                            35
4.25        LNHP and KHP 66 kV transmission line                            35
4.26        100% substation load, KHP and LNHP power evacuation             38
4.27        70% substation load, KHP and LNHP power evacuation              38
4.28        50% substation load, KHP and LNHP power evacuation              39
4.29        30% substation load, KHP and LNHP power evacuation              39
4.30        10% substation load, KHP and LNHP, power evacuation             39
4.31        100% load, effect in existing system, KHP &LNHP evacuation     40
4.32        70% load, effect in existing system, KHP &LNHP evacuation      41
4.33        50% load, effect in existing system, KHP &LNHP evacuation      41
4.34        System Performance with KHP, LNHP and LKHP                      42
4.35        System performances with KHP, LNHP, LKHP and Chame
            Substation.                                                         43
4.36        Load flow result of four feeders of Udipur S/S.                     44




                                                                          iii
Chapter 1 Introduction



CHAPTER 1

Introduction
1.1     General
Nepal, with its very difficult geographic structure, grid expansion to remote area has been very
costly approach for rural electrification as well as to extend for small hydropower
interconnection. Mainly these areas are planned based on the electricity distribution purposes.
This thesis tries to develop the methodology especially for evacuating power from small
hydropower plant in western Nepal by focusing on grid connection as well as local
consumption using existing infrastructure.
Nepal is divided into five development regions, 14 zones and 75 districts. Western
development region is one of the development regions which comprises of three zones,
Lumbini, Dha ulagiri and Gandaki and has 16 districts. The total generating capacity of
interconnected power system of Nepal is 613.557 MW in total, of which about 556.5 MW is
from Hydro Power Stations and 57 MW from Diesel and multi- fuel Power Stations. Obviously
with the emerging scenario of increased power production, expansion of transmission and
distribution system becomes essential. The project thesis, will study power evacuation options
for different small hydropower plant by using the transmission line design program developed
for this purpose and analyze new local market for energy consumption, necessary to evacuate
growth in power production.


This thesis carries out evacuation study to incorporate the major changes in the power scenario
of the western part of Nepal. A power Generation expansion study for different small
hydropower plant is used for the transmission expansion studies. This report carries out
evacuating system study for different selected hydropower plants that will be connected to grid
in the coming years.


1.2     Objective

The major objectives of this thesis is to find out suitable power evacuation system for existing,
under implementation and up coming projects analyzing existing transmission line. The project


                                                                                           1
Chapter 1 Introduction


also focuses on study of the selected existing distribution system in case of local power
evacuation. The areas of work in this thesis consist of:

•         To select Suitable Small Hydro Power Plant in Western part of Nepal.

•         To get related data regarding existing electrical network of the area in the vicinity.

•         To find out transmission line alternatives.

•         Develop software in spread sheet in EXCEL to find out best transmission alternatives
          considering technical aspects.

•         To study system performance using Netbas Simulation.

•         To perform distribution system planning using distribution load flow software.

1.3     Background
In addition to government owned power development agencies (like NEA, MOW, WECS, and
EDD) the private power development agency, Butwal Power Company is also actively
participating in Generation, Transmission and Distribution of electrical power to INPS as well
as local consumers. Butwal Power Company Limited (BPC) is the first private sector Power
Company of Nepal. Today BPC is a leading Hydropower developer of the country.
There are many small hydro power plants that have been identified in western part of Nepal
which are under study. Each year few new hydro power generating potential sites are identified
and undergo pre feasibility study followed by feasibility study. After completion of feasibility
study power purchase agreement is signed with Nepal Electricity Authority (NEA). BPC is
involved in developing 3.5 MW Khudi Hydro Power Plant (KHP), and studying feasibility
study for 2 MW Lower Khudi (LKHP) and 2 MW Jhumdi (JHP) Hydro Power project. Power
evacuation design is very necessary to get PPA signed and the design should be based on
performance standard of grid.


1.4     Performance standard for Grid
Objective:
The objective of the Performance Code is to specify the minimum technical standards to ensure
efficient and reliable operation of Grid [1].



                                                                                              2
Chapter 1 Introduction


Power Quality:
To ensure power quality as per NEA Grid Code standard voltage variation, frequency variation
and transmission loss should be as follows:
a.         Voltage Variation
The system operator shall ensure that the power supply voltage in the grid at major connection
points during normal operating condition shall not deviate by more than +/- 10% of its normal
value.
b.         Frequency Variation
The system operator shall ensure that the fundamental frequency in the system is maintained
between 48.75 Hz. and 51.25 Hz. i.e. +/- 2.5% of 50 Hz, which is the nominal value of
fundamental frequency.
c.         Transmission Loss
The grid owner shall ensure that the transmission loss does not exceed 4.5 % of the received
energy.
1.5       Grid Connection Requirement
As per NEA Grid Code requirement, generator shall maintain Power Factor between 0.85
lagging and 0.95 leading [1].




                                                                                         3
Chapter 2. Existing Electrical System in study area



CHAPTER 2

Existing Electrical system in Study Area

2.1      Existing power plants in western Nepal
In western region there are three zones and sixteen districts. Electricity service is available in
all districts through INPS grid (in eleven districts) and isolated small hydro power stations (in
remaining 5 districts). In either case the electricity service is made available only in limited
area. The total generation of western region is 260.49 MW and most of the generation plants of
the region are situated in Gandaki Zone. The major hydropower plants in this region are 75
MW Marsyandi, 5.1 MW Andhikhola, 14.8 MW Modikhola, 144 MW Kaligandaki 'A', and 15
MW Gandak. The total installed capacity of major hydropower plants is 253.9 MW. There are
twelve existing small hydro power plants of different sizes in western region with total
installed capacity of 6590 kW [2].
                        Table 2.1: Small   Hydro Power Plants of Western Nepal
                                                      Installed
                                                                     Year of
 SNo.       Zone          District     Power Plant    Capacity    Commissioning     Developer
                                                        (kW)
  1       Gandaki       Kaski      Phewa                1088              1967    NEA
  2       Lumbini       Rupandehi  Tinau                1024              1978    NEA
  3       Dhaulagiri    Baglung    Baglung               200              1981    NEA
  4       Dhaulagiri    Mustang    Jomsom                240              1983    NEA
  5       Gandaki       Syrrgja    Syanja                 80              1984    NEA
  6       Gandaki       Kaski      Seti                 1500              1985    NEA
  7       Gandaki       Manang     Chame                  45              1987    NEA
  8       Gandaki       Manang     Manang                 80              1988    NEA
  9       Gandaki       Gorkha     Arughat               150              1990    NEA
  10      Dhaulagiri    Myagdi     Tatopani-I           1000              1991    NEA
  11      Dhaulagiri    Myagdi     Tatopani-II          1000              1995    NEA
  12      Gandaki       Lamjung    Sangekhola            183              2002    SPC
 Note:   SPC=Sange     Power Company; source: System planning, NEA


2.2      Under Study Small Hydro Power Plant in Western Nepal
It is worth mentioning here that many Independent Power Producers (IPP) are showing strong
interest in the development of small hydro power plant in Nepal. In western region only, there




                                                                                                4
Chapter 2. Existing Electrical System in study area


are altogether 24 new small hydro power plants have been identified by private promoters. List
of Identified Small Hydro Power Plants identified by private promoters are tabulated below.
                Table2.2: Small   Hydro Power Projects (1-10 MW) in Western Nepal
                                                                                      Installed
                              Project
 SN.      Project Name                                     Promoter                   Capacity    Informati
                              Location
                                                                                       (MW)       on Source
    1   Bhimkhola             Baglung     Butwal Power Company                              3.1   DOED
        Bijayapur 1           Kaski       Bhagwati HP Development Company (P) Ltd            2    DOED/SH
    2
                                                                                                  PP
    3   Daraudi               Gorkha      Shreerup Hydropower Pvt.Ltd.                       5    DOED
    4   Dharam Khola          Baglung     The Gorkha Hydropower P Ltd.                       5    BPC
    5   Dudh Khola            Manang      Swet Bhairb Pvt Ltd.                              10    DOED
    6   Dordi I               Lamjung     Shah Consult Pvt. Ltd.                             8    DOED
    7   Ghami Khola           Mustang     Cosmic Hydropower Pvt Ltd                         2.5   DODE
    8   Jumdikhola            Gulmi       Butwal Power Company Ltd.                          2    DOED
    9   Karuwa                Kaski       Jhyamolongma Hydropower Dev. Co.(P) Ltd.           6    DOED
  10    Khudi                 Lamjung     Lamjung Electricity Development Co. P Ltd         3.6   SHPP/WI
  11    Kotre                 Kaski       Machhapuchhre HP Development Company               3    SHPP/WI
  12    Lower Myagdi          Myagdi      Nect Center Pvt.Ltd & Him Consult                  5    DOED
        Madkyu Khola          Kaski       Arjun Prashad Paudyal                              5    DOED
  13
        SHP
  14    Madi – 1 Hydro        Kaski        Annapurna Group P/ltd.                           10    BPC
  15    Mardi Khola           Kaski       Gandaki hydro power Development P. Ltd.            3    DOED
  16    Mardi Khola MD-1      Kaski       N/A                                               10    BPC
  17    Nyadi II              Lamjung     Baverian Hydropower Nepal P Ltd                   4.9   SHPP/WI
  18    Pati Khola SHP        Parbat      Unified HP Pvt Ltd.                               1.5   DOED
  19    Paudi Khola SHP       Lamjung     N/A                                               1.5   DOED
  20    Ridi Khola            Gulmi       Ridi Hydropower Development Co.Pvt.Ltd            1.8   DOED
  21    Seti hydropower       Kaski       Seti Hydropower Development Co. (P) Ltd           10    SHPP/WI
  22    Shardi Khola SHP      Kaski       Sarimati Deepal Poudel                            1.7   DOED
        Upper Dharam A        Baglung     Ghumte Hydropower Pvt Ltd                         4.5   DOED
  23
        SHP
  24    Upper Seti - 1        Kaski       Seti Hydropower Development Co. (P) Ltd            3    DOED



2.3     Existing Grid transmission system in western Nepal
The available grid transmission voltage in western region is only 132 kV and sub transmission
voltage is 33 kV. Grid transmission line is connected from east to west through Bardghat,
Butwal and Shivapur areas and from north to south through Pokahara area. Bardghat is one of
the major grid substations in south western part having power sources from Gandak, 15 MW
power station and National Grid. Bardhaghat is connected to Bharatpur by 132 kV single


                                                                                                    5
Chapter 2. Existing Electrical System in study area


circuit transmission line in the east, with Butwal by 132 kV double circuit transmission line in
the west and with Gandak power station by 132 kV double circuit transmission line. Butwal is
another major junction of south-western part of the National Grid having power sources from
National Grid, Andhi Khola, Tinau, Gandak, and Kali Gandaki 'A' power station. Butwal is
connected with Bardhghat by 132 kV single circuit transmission line in the east, with Shivapur
by 132 kV single circuit transmission line in the west and with Kali Gandaki 'A' power station
by 132 kV double circuit transmission line. Shivapur (Chanauta) is also major junction of
south-western part of the National Grid having power sources from INPS. This S/S is
connected with Butwal S/S in the east and Lamahi S/S in the west by 132 kV single circuit
transmission line. Pokhara S/S is connected to Bharatpur via Damauli in the south and is
connected to Modi in the north. The existing transmission lines of western region are tabulated
below.
                     Table 2.3: Existing   132 kV Transmission Line of Western Nepal
                                   Voltage        No. of
              Area                                          Conductor Code   Line Length (km)
                                    Level         Circuit
 Lamahi--Shivpur                         132    single      Bear                      51
 Shivpur--Butwal                         132    single      Bear                      61
 Butwal--Bardghat                        132    double      Bear                      43
 Bardghat--Gandak                        132    single      Panther                   14
 Bardghat--Bharatpur                     132    single      Panther                   70
 Bharatpur--Damauli                      132    single      Wolf                      39
 Damauli--Pokhara                        132    Single      Wolf                      46
 Pokhara--Modi                           132    Single      Bear                      37
 Bharatpur--Marsyangdi                   132    Single      Duck                      25
 Marsyangdi--Suichatar I                 132    Single      Duck                      83
Source: System Planning, NEA
Substations in Pokhara, Damauli, Bardghat, Butwal and Chanauta areas are the main power
sources fo r western region [2].

2.4      Existing Electrical Network in Some Districts of Western Nepal.
To understand the existing electrical network up to distribution level in the western region data
showing the present distribution status of some of the district is explained below.
1.        Palpa
In this district there are altogether 113,361 number of consumer including domestic,
commercial, non-commercial, industrial and others. In this district electrification is done using



                                                                                           6
Chapter 2. Existing Electrical System in study area


both 11 kV and 33 kV distribution systems. The total 11 kV distribution line length is 60 km
and 33 kV distribution line lengths are 118 km. Most of the electrified areas are electrified
using 33/0.4 kV, 99 numbers of distribution transformers of various sizes. In this district there
is one area substation of capacity 6/8 MVA with three feeders East feeder (40 nos. of 11/0.4 kV
transformers), Bazaar feeder (10 nos. of 11/0.4 transformers) and West feeder (30 nos. of
11/0.4 transformers). This substation receives power from Andhi Khola hydro power station
and Butwal grid S/S. There are no existing power plants and also no new identified small power
plants undergoing study.


2.        Parbat
As per NEA, in Parbat district the total number of consumers including domestic, industrial,
commercial, noncommercial and others is 6,941. In Parbat distribution level voltage is 33 kV
and 33/0.4 kV distribution transformer is used for power distribution to consumers. There is
also 11 kV distribution line in this district and the line length is 26.39 km. The 33 kV
distribution line lengths is 89.79 kV. There is no area substation in Parbat and no grid
substation also. In case of power station, there are no existing power plants. Pati Khola SHP,
1.5 MW is the only small hydro power identified by Unified HP Pvt. Ltd. in this district which
is now undergoing feasibility study.


3.        Syanja

According to the information obtained from Syanja Branch, NEA, total number of consumer
including domestic, industrial, commercial, noncommercial and others is 11,200. In this
district Private sector Company, BPC is involved in distributing electricity to about 14,000
numbers of consumers. Total Number of 33/0.4 kV Distribution transformer is 16. In this
district also, distribution has been done in two voltage levels 33 kV and 11 kV. The total line
length of 33 kV distribution line is 18.93 km and the total line length of 11 kV distribution line
is 129.29 km. There are two are area substation under NEA, Badkhola, 33/11 kV, 1.5 MVA
substation and Mirmi, 33/11 kV, 500 kVA substation. There is one existing power station,
Andhi Khola, 5.1 MW, which has 5.3/33 kV substations with three feeders, Walling feeder
with total connected load of 3265 kVA, Galyang feeder with total connected load of 3205 kVA




                                                                                            7
Chapter 2. Existing Electrical System in study area


and NEA feeder, which is connected to Butwal grid substation passing through 200-kVA load.
All these feeders feed load in 33 kV voltage level.



4.        Gulmi district
The Gulmi District is one of the districts of Lumbini Zone in Western Development Region.
There are altogether 79 VDCs in this district. Tamghas is the district head quarter.
Electrification in Gulmi district is very small compare to its size in terms of geography as well
as demography. Only 24 VDCs out of 79 have been partially electrified from 33 kV sub
transmission line joining 5 MW Andhikhola hydropower plant, 40 (1x10 and 1x30) MVA
Butwal Grid substation and 12 MW Jhimruk hydropower plant.
At present the total number of consumers is 8793 including industrial, commercial and others
are enjoying benefits from electricity service in the district. Based on this, the electrification
ratio of the district is only about 15%.
Sub Transmission and Distribution Lines
There is no area substation in this district. 33 kV line network has been used to distribute
electricity with 33/0.4 kV distribution transformers. The 33 kV line originating from
Andhikhola enters the district at Aslewa, which is 17 km from source and joins 33 kV line of
Butwal Grid substation at Baletaksar at a distance of about 77 km from the source.
This 33 kV line further links the 33 kV subtrans mission line from Jhimruk hydropower plant at
Wangla in Arghakhanchi and Tamghas in Gulmi district, forming a looped network of 33 kV,
which covers the load centers of both the districts. The total 33 kV line length in the district is
approximately 158 km. All the existing 33/0.4 kV distribution tappings in the district have been
shown in the single line diagram in Appendix C. This distribution network is consisting of fifty
one (51) 33/0.4 kV distribution transformers of various capacities from 25 KVA to 100 KVA
[3].
In this district, two upcoming small hydro power projects are identified and undergoing study.
Jumdi hydro power (JHP), 2 MW is under feasibility study by Butwal Power Company (BPC)
and Ridhi Khola SHP, 1.8 MW is also under feasibility study carrying out by Ridhi Hydro
Power Development Company.




                                                                                              8
Chapter 2. Existing Electrical System in study area


5.        Lamjung
Lamjung is one of the districts of Gandaki zone in western development region of Nepal. The
existing electrical network in the Lamjung district is comparatively small. According to 8th
power report, NEA, in Lamjung district only 24 VDCs out of 61 VDCs have partial access to
electricity from a single 1.5 MVA, 33/11 kV substation at Udipur.
About 4600 (year: 2001) numbers of consumer including industrial, commercial, and other
have access to electricity in the district. This data shows that the electrification ratio of about
11% and the total energy consumption is about 1472 MWhr. (Year: 2001).
One distinct electric power generating activity in the district is the 183 kW, small- scale
hydropower plant, which is under operation at Sange (of Taghrin VDC) by a private company,
LEDCO.
Source Substation
In Lamjung there is only one 5 MVA, 11/33 kV area substation at Udipur. Source for this area
substation is 132/33 kV Grid substation at Damauli which is 34.5 km from Udipur. In between
Damauli Grid substation and Udipur substation there is another 5 MVA, 33/11 kV substation at
Dumre from where 20 km long 33 kV transmission line is tapped directly to feed Udipur
substation.
Besisahar headquarter of Lamjung district and the area in the vicinity is electrified from four
different outgoing feeders from Udipur substation. Small part of Tanahu district is also
electrified from this substation. The four feeders are Besisahar, Okhari, Bhote Odar and
Nayagaon.
Sub Transmission and Distribution Lines
In Lamjung district the only sub transmission line is 20 km long Dumre-Udipur 33 kV
overhead line constructed on wooden poles using ACSR conductor 65 sq. mm (equivalent
copper area) “Dog”.
In case of distribution lines, about 229 km of (including proposed 128 km) 11 kV line is
distributing electricity up to consumer premises. The conductor used in 11 kV distribution line
are ACSR “Rabbit” and “Weasel”. There are 115 numbers of 11/0.4 kV distribution
transformer of varying capacities from 25 kVA to 200 kVA including existing and proposed
transformers on four outgoing feeders from Udipur substation. Four out of 105 transformers are
located in Tanahu district. The existing electrical network in Lamjung district is presented in


                                                                                             9
Chapter 2. Existing Electrical System in study area


Appendix C. The 11 kV outgoing feeder from Udipur S/S and total connected load in each
feeder of this district is presented below [3].




                                Figure 2.1: 5 MVA, 33/11 Udipur Substation



               Table2.4: Feeder status of 5MVA, 33/11 Udipur substation.
 Name of Feeders              Total No. of Transformer Total kVA
 Besisahar Feeder             36                         1400
 Okhari Feeder                17                         550
 Bhote Odar Feeder            45                         2125
 Majhgau Feeder               17                         575
                  Total Connected kVA                    4650

Power Plants

Khudi, KHP (3.5 MW) is undergoing construction in this district, and is expected to connect
with the NEA Grid at Udipur substation. Lower Nyadi Hydro Power with installed capacity of
4.5 MW is upcoming hydropower which also gets access to grid through 33 kV transmission
line connecting to Udipur substation. Middle Marshyangdi, 70 MW, Hydro power plant is also
under construction and is going to generate power at the end of 2006. Besides these mentioned
hydro power plants there are many other possibility of power generating sites available in this
district. Lower Khudi, 2 MW, and Upper Nyadi 10 MW are already identified and are
undergoing study.



                                                                                        10
Chapter 3. Methodology



CHAPTER 3

Methodology

In Nepal, there are immense opportunities in the field of hydro power development. The record
shows that Nepal has theoretical hydro power potential of 83,000 MW out of which 42,000
MW is technically and economically feasible. In Nepal many of Independent Power Producers
(IPP) are showing strong interest in the development of small scale hydropower. Usually for
small hyd ro Power, power evacuation is becoming great challenge because of difficult
geographic structure and absence of electrical network/grid in the vicinity. Arrangement for
accessing grid substation will make most of the small hydro power plant economically not
feasible so for the small power plant which has enough possibility of local power consumption,
it is required to develop a methodology that will make access to grid as well as satisfy local
power demand. Keeping this in mind, this thesis tries to concentrate in identifying the
evacuation system of Khudi Hydropower (KHP), Nyadi Hydro Power (NHP) and Lower Khudi
Hydropower (LKHP) in western Nepal. Further, detail analysis of evacuation system of Khudi
and Nyadi Hydro Power will be carried out using software developed in spread sheet, Carl
1.0-distribution load flow software and Netbas Simulation.

The methodology adopted for identifying and designing evacuation system is mainly based on
the availability of data for any selected small hydro power. The data collected in this regard
should comprise of information on geography, demography, existing electrical network and
future power expansion plans. After data collection comes analysis part, the analysis part is
divided into two parts viz. technical and financia l. Technical analysis results in feasibility of
selected transmission line alternative regarding technical parameter like voltage, line length,
power to be transmitted, power factor and efficiency. Financial analysis will decide in selection
of one alternative among many technically feasible alternatives.

3.1     Data Collection
From data collection regarding existing electrical network of different district of western
Nepal, help in locating the power house site of new coming small hydro power plants. Exact
location of most of the new under study power plant is not known so knowledge of existing


                                                                                           11
Chapter 3. Methodology


electrical network including 11 kV distribution, 33 kV distribution or sub transmission line,
33/11 kV substation and 132/33/11 kV Grid substation is very essential because ultimately the
power generated must be evacuated there.

Difficulty in designing power evacuation system is quite similar for almost all identified new
small hydro power plants. All hydro power station sites are far from major load centers and
obviously far from grid access. So, in this thesis, for studying evacuation system of western
Nepal, Lamjung district is selected because, in Lamjung district there are comparatively
smaller hydropower plants identified by different IPPs and are under going different stages of
study. The small hydropower plants identified in this district are 3.5 MW Khudi Hydro Power
(KHP), 4.5 MW Lower Nyadi Hydro Power (LNHP), 2 MW Lower Khudi Hydro Power
(LKHP) and 10 MW Upper Nyadi Hydro Power Plant (UNHP). Among these, Khudi Hydro
Power Plant has started construction work, and detail study of Lower Nyadi Hydro Power is
under progress. Now, for designing evacuation system for these two hydro power plants, data
based on geography and demography is acquired from topographic map, data regarding all
existing as well as proposed electrical network of whole Lamjung district is taken from 8th
Power Report, NEA, and some of the data related to electrical infrastructure have been updated
with the latest data acquired during field visit of Western Nepal. The existing electrical
network of Lamjung district is presented in Appendix C.


3.2     Transmission line alternative
Topographic Map shows all required information regarding land, water, lakes, pond, rivers,
stream, canals, dams, bridge, mountains, hills, valleys cliffs, towns, cities, roads, boundaries
and other geographic and demographic features. Study of Topographic map gives the
preliminary idea about the transmission line route. Selection of transmission line route is based
on a procedure which should consider restricting factor like safety, engineering and
technology, system planning, environmental, institutional and aesthetics. The transmission
route selection is based on available right of way and results of system analysis. Usually the
route is selected within the country on private right of way in order to obtain most possible
direct route and to stay away from road, buildings, highway etc. After finalizing the
transmission route/s technical and financial analysis is carried out for choosing best alternative



                                                                                           12
Chapter 3. Methodology


if there are many. Detail study for identifying the transmission line route is out of scope of this
thesis. For carrying out technical and financial analysis of the selected transmission line,
                                            o
program developed on MS excel will be used, f llowed by Netbas simulation for studying
system performance, finally using available data distribution system planning is carried out
with Carl1.0 (program for load flow calculation of 11 kV radial distribution network).

3.3     Available Transmission Capacity
Transmission Capacity is the maximum power that can be delivered from power generating
station to the distribution station. Transmission capacity depends on line length, size of
conductors and voltage level. While determining transmission capacity of new transmission
system, possibility of addition of new power plant is to be considered. Available Transmission
Capacity (ATC) is difference between transmission margin and present line loading.

3.4     Transmission Margin
Transmission margin is the maximum allowable power that can be transmitted without
violating the transmission line criteria which may be performance standard or control and
protection settings used in primary and secondary distribution substations.

3.5     Performance of Transmission line
Efficiency and Voltage regulation are the key parameters that determine the performance of
transmission line. For any type of transmission line, calculation based on ABCD constants for
determining efficiency and regulation can be done using computer program. If the efficiency
and regulation are not within prescribed value then it is necessary to revise the calculation
using thick conductor cross-section and changing the conductor configuration. In some cases it
may be necessary to use a higher transmission voltage in the revised design. Detail of
transmission line design is presented in Appendix A.

3.6     Distribution system planning
The project will focus on the present distribution system and will work out for future
distribution planning which is the most important parameter required for designing power
evacuation system. Transmission and distribution planning is done so that present and future
power required by local consumer is identified and help in designing required evacuation
system. Distribution planning will be done using load forecasting of study area which includes




                                                                                            13
Chapter 3. Methodology


study of load growth pattern and load flow analysis. This thesis covers the load flow analysis
part only.

3.7     Spread Sheet Calculation for Conductor selection and Voltage [2]
For the selection of optimum conductor size and transmission voltage a program is developed
in spread sheet. The selection is based on capitalized cost per km of transmission line. This
method is mainly applicable to transmission lines that are not subject to load growth. Such
transmission line would be from new power plants to the nearest grid connection point in the
existing system. Another important use of this spread sheet is to "screen" the number of
alternatives down to a manageable level before full system studies are undertaken.
Basic Formula
The selection of transmission lines for the planned power plants in Nepal are based on
economic evaluation of different line/tower solutions over the lifetime of the project. The
optimization takes into account the investment cost, cost of transmission losses and operation
and maintenance costs.
The calculation is performed on a km transmission line basis and is as such not dependent on
the length of the transmission line. The following formulas apply to the calculation:
        K Total = K Investment + K Losses + K o& m   [NRs. / km]                        Eq. 1


                                2
                      P       
        K Losses   =  Peak
                     U         .R.TLoss .k E .D
                                                    [kNRs. / Km]                       Eq. 2
                      Rated   


                                 CO & M
        K O& M = K Investment.          .D           [NRs. / km]                        Eq. 3
                                  100
Where, PPeak =Maximum Transmitted Power [MW], U Rated = Rated AC line Voltage [kV], R =

AC line resistance [? / km], T Loss = Loss Duration [hours], k E = Energy Cost [NRs/kWh], D

= Discount Factor, CO& M = Annual Operation & Maintenance cost [% of initial investment].




                                                                                        14
Chapter 3. Methodology


Plant Loss Duration
The equivalent loss duration is calculated from the plant factors. The equivalent loss duration
should be understood as the time the plant will have to operate on rated capacity in order to
produce the annual losses, and is calculated from:

          TUtilisation  1  TUtilizatio             
                                                 2
            2
                        1 + 1 −
                                   2
                                                    
TLoss   =              .                 n
                                                        [Hours]                           Eq. 4
                            
                            2         2            
           8760
                        
                                  8760              
Energy Cost
The energy cost normally to be used for optimization of transmission line is the long run
marginal cost of generation. In Nepal, it has been agreed that an average incremental cost of
generation better reflects the real value and is therefore used. The average incremental cost of
generation is 6.02 USC/kWh.
Operation & Maintenance
The operation and maintenance cost of transmission line is set to 1.5% of initial investment by
NEA. Typical figures range from 0.5% to 1.5%, and Nepal may be in the upper range of this
due to the recurring monsoon and frequent landslides. An annual operation and maintenance
cost of 1.5% has therefore been used in the optimization.
Annual Outage
Outage means power transmission failure due to unavailability of transmission line during
faulty condition. In Nepal, for 132 kV transmissions line the annual outage is taken as
0.28hrs/km.
Discount Factor
The discount factor represents the discounted value of fixed annual payments of one unit each
year of the lifetime. With 25 years technical lifetime and 10% discount rate, the discount factor
is 9.08.

      (1 + i ) N − 1
DF =             N 
                                                                                           Eq. 5
      i (1 + i ) 
Where, DF is discount factor, i is discount rate in percent, N is Number of compounding
periods in years.




                                                                                          15
Chapter 3. Methodology


Spreadsheet Result:
Input to the spreadsheet program are line length, power factor, voltage level and power to be
transmitted from generation source to distribut ion substation. The program will carry out
transmission line design analysis using selected four different conductors from a given list. The
result is the outcome of technical and financial analysis. For technical analysis the program will
give, voltage regulation, efficiency of line and line loss. Changing either conductor size or
voltage level, the result can be made within required voltage regulation and efficiency.
Financial analysis is based on transmission line cost with selected conductor only. For more
than one conductor satisfying both criteria i.e. voltage regulation and efficiency the best
conductor is selected for minimum KTotal in given in Equation 1.
Input
Input parameters in spread sheet calculation for selecting conductor are power to be delivered
in MW, line length (L) in km and power factor (Cosf ).
Testing criteria
The selected conductor should meet both efficiency and voltage regulation criteria. If one of
these criteria is violated, the conductor is not suitable for the transmission line. As per NEA
Grid Code efficiency should be not less than 95.5% and voltage regulation should be ±10 %.
Voltage Regulation
Voltage regulation of a line is the change in voltage at the receiving end when full load at a
given power factor is removed keeping sending end voltage constant.
                      Vrnl − Vrfl
% Re gulation =                                                                             Eq. 6
                          Vrfl

Where,
         Vrnl         =             magnitude of receiving-end voltage at no load.
         Vrfl         =             magnitude of receiving-end voltage at full load.
Transmission Efficiency
                    PR
         η line =      * 100%                                                               Eq. 7
                    Ps
         Where,
         PR           =             Power to be delivered at receiving end
         Ps           =             Power sent at the sending end


                                                                                           16
Chapter 3. Methodology




                                                                        Conductor and Voltage Optimzation



                                      4800


                                      4300


                                      3800                                                                                        Weasel_33
                                                                                                                                  Rabbit_33
           Capitalized Cost [kNRs.]




                                      3300                                                                                        Beaver_33
                                                                                                                                  Dog_33
                                                                                                                                  Tiger_33
                                      2800                                                                                        Wolf_33
                                                                                                                                  Lynx_33
                                      2300                                                                                        Panther_33
                                                                                                                                  Dog_66
                                                                                                                                  Wolf_66
                                      1800                                                                                        Panther_66
                                                                                                                                  Lion_66
                                      1300


                                      800


                                      300
                                             1 Mw   2MW         3MW            4MW         5MW        6 MW         7MW   8 MW
                                                                                Peak Load [MW]


                                                    Figure 3.1: Conductor   optimization sheet using spreadsheet



                                                                                                                                17
Chapter 3. Methodology



3.8     Carl 1.0
In order to evaluate the performance of a power distribution network and to examine the
effectiveness of proposed alterations to a system in the planning stage, it is essential that a load
flow analysis of the network is carried out. The load flow studies are normally carried out to
determine:
1.       The flow of active and reactive power in network branches.
2.       Effect of additions or alterations on a system.
3.       Optimum system loading conditions.
4.       Optimum system losses.


Input
For this software-Carl1.0, the input parameters are related to the 11 kV radial distribution
feeders only. Input data related to 11 kV feeder are; substation capacity (MVA), voltage level
(kV), name of load centers, name of sending end node and receiving end node, distribution load
(kVA of 11/0.4 kV distribution transformer), power factor, length of 11 kV line between
sending end and receiving end of a branch and finally type conductor. This software allows
only three conductor options viz. 'dog’, ‘rabbit’ and ‘weasel’ because in Nepal, only
conductors ‘dog’, ‘rabbit’ and ‘weasel’ are used in the distribution level.
Output
The output of the software is directly saved in the MS Excel sheet. The results of load flow are;
total power loss in each branch feeders (sum of loss in all branches), total power flow in each
branch, minimum voltage in percent ; voltage drop in each branch, voltage at each receiving
end, location of node with minimum voltage, length of different type of conductor used, total
power loss of the feeder and total power flow in the feeder.
Using this software conductor selection, feeder load management and voltage regulation can be
done. This software is used just to study the status of local load centers.

3.9     Netbas Simulation
This software is developed by Powel Company, Norway. Netbas Simulation is very helpful in
solving load flow ana lysis, short circuit analysis and other power system analysis. In this thesis,
Netbas is used for determining the system performance after connecting a small power plant in



                                                                                             18
Chapter 3. Methodology


the existing electrical network. The comparison between status of existing electrical network
before and after connecting new power plant will definitely help in selecting best evacuation
option for upcoming hydropower plant.
As per grid code, NEA, in Nepal study of system performance is necessary for any new hydro
power plant more than 1 MW, willing to connect to the grid. System performance shall include
the following information:
1.       Power flow direction during different time frame, loading conditions.
2.       Change in voltage regulation in existing electrical network
3.       Change in transmission line loss in existing electrical network.
These required data can be easily determined using Netbas Simulation


3.10 Evacuation System for KHP, LNHP and LKHP.
The methodology described above is used to study evacuation system of KHP, LNHP and
LKHP in Lamjung district. These power plants are under different stages of development. The
present status shows that KHP will come first then LNHP and at last LKHP. For all these power
plants the nearest available existing grid is 33/11 kV, 5 MVA, Udipur substation which is fed
by 132/33 kV grid substation at Damauli, 34.5 km away at Tanahu district. There are no other
options available for power evacuation from these power plants. Therefore, this thesis
concentrates on detail study for evacuating power using existing transmission system for
different loading conditions.




                                                                                      19
Chapter 4. Results and Discussion



CHAPTER 4

Results And Discussions

Existing system in Lamjung district is shown below. Udipur substation is 14 km away from
Dumre substation and connected with 33 kV transmission line with conductor 'dog'. Dumre,
Udipur and Anbu Khaireni substations are fed by Damauli 132/33 substation through 14.5 km
long 33 kV transmission line from Damauli S/S to Dumre S/S. Single line diagram of existing
33 kV sub transmission network is shown in figure below.




                        Figure 4.1: Existing Electrical System of Lamjung District


4.1     Existing System Result
Existing system analysis will help in finding out the present performance and make us able to
compare with different options of addition of hydro power plant or addition of bulk load. Three
area substations Dumre S/S, Udipur S/S and Anbu S/S and one grid substation, Damauli S/S
will be affected by addition of upcoming SHP. Load flow is carried out for different loading
condition.


                                                                                        20
Chapter 4. Results and Discussion


Case I : Full Load
In 100% load, i.e. 15 MVA (sum of full load of three substation, 13.5 MW at 0.9 pf), swing
bus- Damauli substation will generate 14.83 MW including line losses. Maximum voltage drop
is at Udipur which is 13.68 % i.e. voltage at Udipur is only 28.486 kV. In this case Damauli-
Dumre line section is over loaded, 106.23%. The result of Netbas Simulation for full load case
is tabulated below.
                                Table.4.1: Full Sub Stations Load, Existing System

 Conductor                                         Dog
 Generation at Damauli (slack bus)                 14.83 MW, 8.32 Mvar
 Total voltage independent load                    13.5 MW, 6.58 Mvar
 Total Loss in line sections                       1.33 MW, 1.74 Mvar
 Total % of transmission Loss                      8.97 %
 Max. Voltage Drop and location                    13.68 %, Udipur
 Heaviest loaded line                              Damauli- Dumre, 106.23%


Case II: 70 % Load
In 70% load, i.e. 10.5 MVA (9.45 MW at 0.9 pf), the swing bus, Damauli substation will
generate 10.045 MW including line losses. Maximum voltage drop is at Udipur which is 9.11%
i.e. voltage at Udipur is only 29.995 kV. In this case Damauli- Dumre section is heaviest loaded
line, 71.22 %. The result of Netbas Simulation for this case is tabulated below.
                                Table.4.2: 70 % Substations Load, Existing System

 Conductor                                          Dog
 Generation at Damauli (slack bus)                  10.045 MW, 5.39 Mvar
 Total voltage independent load                     9.45 MW, 4.61 Mvar
 Total Loss in line sections                        0.6 MW, 0.78 Mvar
 Total % of transmission Loss                       6.35 %
 Max. Voltage Drop and location                     9.11 %, Udipur
 Heaviest loaded line                               Damauli- Dumre, 71.22%




                                                                                         21
Chapter 4. Results and Discussion


Case III: 50 % Load
In this case all three area substations are considered to be operated in half load only. Total
generation in Damauli S/S is 7.04 MW including losses 0.29 MW in all line sections and the
total load of all substations is 6.75 MW. The maximum voltage drop is 6.71 % at Udipur S/S,
which is 30.92 kV. The heaviest loaded line is Damauli-Dumre, 49.6%.
                                Table 4.3: 50% Substations Load, Existing System

 Conductor                                             Dog
 Generation at Damauli (slack bus)                     7.04 MW, 3.67 Mvar
 Total voltage independent load                        6.75 MW, 3.29 Mvar
 Total Loss in line sections                           0.29 MW, 0.38 Mvar
 Total % of Transmission Loss                          4.12 %
 Max. Voltage Drop and location                        6.31 %, Udipur
 Heaviest loaded line                                  Damauli- Dumre,49.6%


Case IV: 30 % Load
In this test case all substations are considered to be running in 30% loading. Total power drawn
from Damauli S/S is 4.15 MW including 0.099 MW losses in all line sections. The maximum
voltage drop is 3.69 % at Udipur which is 31.78 kV. In this case also the heaviest loaded line is
Damauli- Dumre, 29.06%.
                                Table.4.4: 30 % Substations Load, Existing System

 Conductor                                          Dog
 Generation at Damauli (slack bus)                   4.15 MW, 2.01 Mvar
 Total voltage independent load                      4.05 MW, 1.97 Mvar
 Total Loss in line sections                        0.099 MW, 0.13 Mvar
 Total % of Transmission Loss                       2.38 %
 Max. Voltage Drop and location                     3.69%, Udipur
 Heaviest loaded line                               Damauli- Dumre, 29.06%




                                                                                          22
Chapter 4. Results and Discussion


Case V: 10 % Load
In this test case all substations are considered to be running in 10 % loading. Total power drawn
from Damauli S/S is 1.36 MW including 0.01 MW losses in all line sections. The maximum
voltage drop is 1.2 % at Udipur which is 32.605 kV.
                                Table4.5: 10 % Substations Load, Existing System

 Conductor                                       Dog
 Generation at Damauli (slack bus)                1.36 MW, 0.67 Mvar
 Total voltage independent load                  1.35 MW, 0.66 Mvar
 Total Loss in line sections                     0.01 MW, 0.14 Mvar
 Total % of Transmission Loss                    0.74 %
 Max. Voltage Drop and location                  1.2%, Udipur
 Heaviest loaded line                            Damauli- Dumre,


Case VI: 100% load with “Wolf”
In full load capacity, with conductor ‘wolf’ the total system loss is 6.05% which is
unacceptable and the voltage drop is 10.41%, so the existing system will be inefficient even if
conductor wolf is used.
                          Table 4.6: 100% Substations load with 'wolf', Existing system
 Conductor                                       Wolf
 Generation at Damauli (slack bus)               14.37 MW, 8.15 Mvar
 Total voltage independent load                  13.5 MW, 6.58 Mvar
 Total Loss in line sections                     0.87 MW, 1.57 Mvar
 Total % of Transmission Loss                    6.05 %
 Max. Voltage Drop and location                  10.41 %, Udipur
 Heaviest loaded line                            Damauli- Dumre


Case VII: 80% load with “Wolf”
In 80% load capacity the total line loss is 4.5% and maximum voltage drop is 8.1%. Generation
at Damauli S/S is 11.31 MW and total substation load is 10.8 MW.




                                                                                          23
Chapter 4. Results and Discussion




                           Table 4.7: 80% Substations load with 'wolf', Existing system
 Conductor                                       Wolf
 Generation at Damauli (slack bus)               11.31 MW, 6.215 Mvar
 Total voltage independent load                  10.8 MW, 5.26 Mvar
 Total Loss in line sections                     0.511 MW, 0.952 Mvar
 Total % of Transmission Loss                    4.5%
 Max. Voltage Drop and location                  8.1 %, Udipur
 Heaviest loaded line                            Damauli- Dumre, 56.45%


Case VIII: 50% load with “Wolf”, Existing System
In this case the system performance is within acceptable limits. The voltage regulation of
4.88% and total transmission loss of 2.8% with total generation of 6.95 MW at slack bus makes
the system quite normal.
                           Table 4.8: 50% Substations load with 'Wolf', Existing system
 Conductor                                       Wolf
 Generation at Damauli (slack bus)               6.95 MW, 3.64 Mvar
 Total voltage independent load                  6.75 MW, 3.3 Mvar
 Total Loss in line sections                     0.195 MW, 0.35 Mvar
 Total % of Transmission Loss                    2.8 %
 Max. Voltage Drop and location                  4.88 %, Udipur
 Heaviest loaded line                            Damauli- Dumre,49.0%


Discussion: Existing Electrical Network
Usually the substation capacity is determined from the peak load forecast of 15th year from the
date of its construction. The analysis of system is carried out for different loading condition in
the substations. From load flow analysis using Netbas simulation it is found that transmission
capacity of Damauli- Dumre 33 kV transmission line is 13.5 MW without over loading. Full
capacity of this line cannot be used because of poor voltage regulation (13.68 %) and
transmission loss (8.97 %). From Case III Transmission Margin is 7 MW. If the total load
demand exceeds 50%- case III, then the total transmission loss exceeds 4% and in this case the
total power drawn from Damauli S/S (swing bus) is 7 MW. For Case I, II and III, there is no


                                                                                           24
Chapter 4. Results and Discussion


Available Transmission Capacity in existing system because total line loss is more than 4%. In
case IV the total line loss is only 2.38% so more power can be drawn from Damauli S/S
therefore ATC is 2.54 MW and in case V ATC is 5.68 MW.
As the existing system performance using conductor ‘dog’ is very inefficient when the load
demand exceeds 50% of total substation capacity. Therefore for better performance conductor
with higher cross section shall be used. Analysis of system performance using conductor ‘wolf
‘ shows that the existing system will be acceptable up to load demand of 80% of total
substation capacity. By changing the existing conductor "Dog" with conductor "Wolf" the
transmission margin can be increased to 11 MW.

4.2     KHP Evacuation System
This section shows the analysis for Khudi Hydro Plant (KHP) power evacuation. As Lower
Nyadi Hydro Project (LNHP) is also coming in near future so the Khudi Switching Station will
connect both power sources and feed down to Damauli S/S through Udipur S/S and Dumre S/S.
First step is to analyze transmission system of KHP up to Khudi Switching station (KSw/S) and
then Udipur S/S using spreadsheet calculation. Transmission line from KHP to Khudi
switching station is only 0.9 km and this line will be used only for transferring power from
KHP to Khudi switching station. From spread sheet calculation in 33 kV voltage level
conductor ‘Beaver’, ‘Dog’, ’Wolf’ and ‘Panther’ is found to be technically feasible but
financial analysis shows that conductor ‘Wolf’ is the best having lowest NPV of Investment
(inclusive of losses, O&M and outages over the period of 25 years). The spread sheet result is
tabulated below:
                         Table 4.9: Spread Sheet Calculation for KHP Evacuation System
                                           Technical Part
 Conductor                                    Beaver      Dog              Wolf          Panther
 Line Length (km)                               0.9               0.9           0.9            0.9
 Receiving End Voltage (kV)                   32.95             32.96         32.97          32.97
 Voltage Regulation (%)                        0.23              0.13           0.1           0.09
 Line Losses (kW)                              4.80              3.44           2.3           1.72
 % transmission loss                            0.2               0.1          0.07           0.05
 Line Efficiency (%):                         99.86              99.9         99.93          99.95
 Power Delivered (MW)                          3.49              3.49
                                        Economical Part
 NPV of Investment inclusive of losses,        1556              1375          1335           1378
 O&M and outages (NRs.'000)




                                                                                             25
Chapter 4. Results and Discussion



                                                    Conductor and Voltage Optimzation



                             4800


                             4300


                             3800
  Capitalized Cost [kNRs.]




                             3300                                                                           Weasel_33
                                                                                                            Rabbit_33
                                                                                                            Beaver_33
                             2800                                                                           Dog_33
                                                                                                            Tiger_33
                             2300                                                                           Wolf_33
                                                                                                            Lynx_33
                                                                                                            Panther_33
                             1800


                             1300


                             800
                                                                                        Wolf_33
                             300
                               1 Mw    2MW                   3MW                        4MW       5MW
                                                        Peak Load [MW]


                                      Figure 4.2: Conductor Selection for KHP evacuation
Before LNHP connected to the Khudi Switching Station KHP will get connected in Udipur
Substation through 14km long 33 kV transmission line from Khudi Switching Station to
Udipur S/S. Now in this case the total transmission length is 14.9 km and spread sheet
calculation shows that conductor "Wolf" is best and have lowest NVP of Investment. The
details of spread sheet result are tabulated below.
                       Table.4.10: Spread Sheet calculation for KHP Evacuation System
                                           Technical Part
 Conductor                                         Beaver          Dog         Wolf                     Panther
 Line Length (km)                                     14.9         14.9        14.9                        14.9
 Power to be Transmitted (MW)                         3.50         3.50         3.5                         3.5
 Receiving End Voltage (kV)                          32.11        32.29       32.44                       32.52
 Voltage Regulation (%)                               2.71         2.16        1.69                        1.44
 Line Losses (kW)                                    79.48        56.90       38.16                       28.45
 % transmission loss                                  2.21         1.59        1.07                         0.8
 Line Eficiency (%):                                 97.79        98.41       98.93                        99.2
 Power Delivered at the load end (MW)                 3.41         3.43        3.45                        3.46
                                         Economical Part
 NPV of Investment inclusive of Losses,
 O&M and Outages (NRs.’000)                         25696        22717       22083                       22803



For studying the affect of connecting KHP to Udipur S/S Netbas Simulation is used. Power
from KHP will get grid access at Udipur S/S and will feed power to local area through 33/11



                                                                                                          26
Chapter 4. Results and Discussion


kV Udipur S/S. The excess power is transmitted to Dumre S/S and feed power there also and
finally excess power will be transmitted to Grid. Netbas Simulation is carried out for studying
the following system performance under different loading condition of Substations.




                                    Figure 4.3: KHP Evacuation System
Case I: Full load
In full load, i.e. 15 MVA (13.5 MW at 0.9 pf), swing bus i.e. Damauli substation will generate
10.73 MW including line losses. Power generation from Khudi Power plant is 3.5 MW.
Maximum voltage drop is at Anbu Khaireni which is 8.66 % i.e. voltage at Anb u Khaireni is
only 30.14 kV. In this case Damauli- Dumre line section is heaviest loaded with 73.58%. The
result of Netbas Simulation for full load case is tabulated below.
                                    Table.4.11: Full Load, KHP Power Evacuation
 Conductor                                        Dog
 Generation at Damauli (slack bus)                 10.73MW, 4.85 Mvar
 Total Generation                                 14.23 MW, 7.7 Mvar
 Total voltage independent load                    13.5 MW, 6.58 Mvar
 Total Loss in line sections                      0.68 MW, 0.9 Mvar
 % of total transmission line loss                4.77 %
 Max. Voltage Drop and location                    8.66%, AnbuKhareni
 Heaviest loaded line                             Damauli- Dumre, 73.58%




                                                                                        27
Chapter 4. Results and Discussion


Case II: 70% load
In 70% load, i.e. 10.5 MVA (9.45 MW at 0.9 pf), the swing bus, Damauli substation will
generate 6.27 MW including line losses. Power generation from KHP is 3.5 MW. Maximum
voltage drop is at AnbuKhaireni which is 5.75 % i.e. voltage at AnbuKhaireni is only 31.1 kV.
In this case Damauli- Dumre section is heaviest loaded line, 45.7 %. The result of Netbas
Simulation for this case is tabulated below.
                            Table.4.12: 70 % Substation Load, KHP Powe r Evacuation
 Conductor                                         Dog
 Generation at Damauli (slack bus)                  6.27 MW, 3.76 Mvar
 Total Generation                                  9.77 MW, 5.15 Mvar
 Total voltage independent load                    9.45 MW, 4.61 Mvar
 Total Loss in line sections                       0.29 MW, 0.38 Mvar
 % of total transmission line loss                 2.97 %
 Max. Voltage Drop and location                    5.75%, AnbuKhareni
 Heaviest loaded line                              Damauli- Dumre, 45.7%

Case III: 50% load
In this case all three area substations are considered to be operated in half load only. Total
power drawn from Damauli S/S is 3.44 MW including losses 0.16 MW in all line sections and
the total load of all substations is 6.75 MW (at 0.9 pf). Power generation from KHP is 3.5 MW.
The maximum voltage drop is 3.94% at AnbuKhaireni S/S, which is 31.70 kV. The heaviest
loaded line is KHP-Khudi Sw/S, 30.91%.
                       Table.4.13: 50 % Substation Load, KHP Power Evacuation
 Conductor                                        Dog
 Generation at Damauli (slack bus)                3.44 MW, 3.15 Mvar
 Total Generation                                 6.94 MW, 3.64 Mvar
 Total voltage independent load                   6.75 MW, 3.3 Mvar
 Total Loss in line sections                      0.16 MW, 0.21 Mvar
 % of total transmission line loss                2.3 %
 Max. Voltage Drop and location                   3.94 %, AnbuKhaireni
 Heaviest loaded line                             KHP-Khudi Sw/S,30.91 %

Case IV: 30% load
In this case all substations are considered to be running in 30% loading. Total power drawn
from Damauli S/S is 0.69 MW including 0.11 MW losses in all line sections. Power generation
from KHP is 3.5 MW. Power generation from KHP is 3.5 MW. The maximum voltage drop is
2.21 % at AnbuKhaireni which is 32.27 kV. In this case also the heaviest loaded line is
KHP-Khudi Sw/S, 30.8 %.



                                                                                        28
Chapter 4. Results and Discussion


                       Table.4.14: 30 % Substation Load, KHP Power Evacuation
 Conductor                                        Dog
 Generation at Damauli (slack bus)                 0.69 MW, 2.64 Mvar
 Total Generation (MW)                            4.19 MW, 2.26 Mvar
 Total voltage independent load                   4.05 MW, 1.97 Mvar
 Total Loss in line sections                      0.11 MW, 0.15 Mvar
 % of total transmission loss                     2.62 %
 Max. Voltage Drop and location                   2.21%, AnbuKhaireni
 Heaviest loaded line                             KHP-Khudi Sw/S, 30.8%

Case V: 10% load
In this case all substations are considered to be running in 10 % loading. Total power fed to
Damauli S/S is 1.98 MW including 1.43 MW losses in all line sections. Power generation from
KHP is 3.5 MW. The maximum voltage drop is 0.55 % at AnbuKhaireni which is 32.82 kV. In
this case also the heaviest loaded line is KHP-Khudi Sw/S, 32.39%.
                       Table.4.15: 10 % Substation Load KHP Power Evacuation
 Conductor                                        Dog
 Generation at Damauli (slack bus)               -1.98 MW, 2.21 Mvar
 Total Generation                                1.53 MW, 1.0 Mvar
 Total voltage independent load                  1.35 MW, 0.66 Mvar
 Total Loss in line sections                     0.143 MW, 0.19 Mvar
 % of total transmission line loss               9.34 %
 Max. Voltage Drop and location                  0.55%, AnbuKhaireni
 Heaviest loaded line                            KHP-Khudi Sw/s, 32.39%


Case VI: 100% load with conductor ‘wolf’

As from economical analysis conductor ‘wolf’ is the best one. Using this conductor the total
transmission loss is 3.42%. Maximum voltage drop is 7.33% only. The power drawn from
Damauli S/S is 10.52 MW and power generation from KHP is 3.5 MW.
                       Table.4.16: 100% Load with 'Wolf', KHP power evacuation
 Conductor                                        Wolf
 Generation at Damauli (slack bus)                10.52MW, 5.23 Mvar
 Total Generation (MW)                            14.02 MW, 7.62 Mvar
 Total voltage independent load                   13.5 MW, 6.58 Mvar
 Total Loss in line sections                      0.48 MW, 0.84 Mvar
 % of total transmission loss                     3.42 %
 Max. Voltage Drop and location                   7.33%, AnbuKharireni
 Heaviest loaded line                             Damauli- Dumre, 73.4%




                                                                                       29
Chapter 4. Results and Discussion


Case VII: 50% load with conductor ‘wolf’

In this case using wolf conductor the system performance is very much improved. The total
line loss is only 1.62% and maximum voltage drop is 3.41% at AnbuKhaireni.
                  Table.4.17: 50% Substation Load with 'Wolf', KHP power evacuation
 Conductor                                        Wolf
 Generation at Damauli (slack bus)                3.39 MW, 3.11 Mvar
 Total Generation (MW)                            6.89 MW, 3.62 Mvar
 Total voltage independent load                   6.75 MW, 3.29 Mvar
 Total Loss in line sections                      0.112 MW, 0.196 Mvar
 % of total transmission loss                     1.62 %
 Max. Voltage Drop and location                   3.41%, AnbuKhaireni
 Heaviest loaded line                             KHP-Khudi Sw/S, 30.94%

Effect in NEA line:
Udipur S/S is feeding in Lamjung district through outgoing four feeders. Power source for this
S/S is Damauli grid S/S 34.4 km away. KHP, on the other hand is only 14 .9 km away from
Udipur S/S and connecting 33 kV transmission line from KHP to Udipur will change the
existing electric al system. Existing transmission line sections are Udipur S/S to Dumre S/S
(USS to DuSS), Dumre SS to Damauli SS (DuSS to DaSS) and Dumre SS to AkSS (Dumre SS
to Anbu Khaireni SS).


Case I: 100 % loading
With addition of KHP in Udipur S/S line losses in three existing section of NEA has improved
also voltage drop in these sections has greatly reduced. The total losses in these line sections
reduce from 1.326 MW to 0.606 MW. The maximum voltage drop in Dumre – Damauli section
has also improved from 10.29 % to 6.61 %. The result shows that if KHP is connected then
Udipur, Anbu Khaireni and Damauli S/Ss can be run in full load without violating the voltage
regulation and efficiency limits. The result from Netbas Simulation is tabulated below.




                                                                                          30
Chapter 4. Results and Discussion


                 Table.4.18: 100% Substation Load, effect in existing system with KHP.
 SNo         Section        Length,       Previous        New Line Previous V New
                            km            Line Loss       Loss     Drop %     V Drop %
                                          (kW)            (kW)
 1           USS to         20            170.06          7.88     5.03       0.408
             DuSS
 2           DuSS to        14.5          1058.17         507.74        10.29            6.61
             DaSS
 3           DuSS to        12            97.92           91.13         2.92             2.69
             AkSS
                                    Total 1326.15         606.75

Case II: 70% loading
After addition of power from KHP in Udipur S/S line losses in three existing section of NEA
has improved. Voltage drop in these sections has greatly reduced. The total losses in these lines
sections reduce from 0.594 MW to 0.238 MW. The maximum voltage drop in Dumre –
Damauli section has also improved from 6.63 % to 4.26 %. The result shows that if KHP is
connected then Udipur S/S, Anbu Khaireni S/Ss and Damauli S/S can be run without violating
the voltage regulation and efficiency limits. The result from Netbas Simulation is tabulated
below.

                  Table.4.19: 70% Substation Load, effect in existing system with KHP.
 SNo         Section        Length,       Previous        New Line Previous V New
                            km            Line Loss       Loss     Drop       V Drop
 1           USS to         20            75.15           1.17     3.17       1.91
             DuSS
 2           DuSS to        14.5          475.6           195.75        6.63             4.26
             DaSS
 3           DuSS to        12            43.95           41.94         1.85             1.76
             AkSS
                                    Total 594.7           238.86

Case III: 50 % loading
After addition of power from KHP in Udipur S/S line losses in three existing section of NEA
has improved. Voltage drop in these sections has greatly reduced. The total losses in these lines
sections reduce from 0.288 MW to 0.111 MW. The maximum voltage drop in Dumre –
Damauli section has also improved from 4.51% to 2.84 %. The result shows that if KHP is
connected then Udipur S/S, Anbu Khaireni S/Ss and Damauli S/S can be run in without




                                                                                                31
Chapter 4. Results and Discussion


violating the voltage regulation and efficiency limits. The result from Netbas Simulation is
tabulated below.

                  Table.4.20: 50% Substation Load, effect in existing system with KHP.
 SNo         Section        Length,       Previous         New Line Previous V New
                            km            Line Loss        Loss     Drop       V Drop
 1           USS to         20            36.09            10.93    2.13       0.05
             DuSS
 2           DuSS to        14.5          230.59           79.61        4.51             2.84
             DaSS
 3           DuSS to        12            21.29            20.6         1.25             1.21
             AkSS
                                    Total 287.97           111.14

Case IV: 30 % Loading
After addition of power from KHP in Udipur S/S line losses in three existing section of NEA
has improved. Voltage drop in these sections has greatly reduced. The total losses in these lines
sections reduce from 0.098 MW to 0.064 MW. The maximum voltage drop in Dumre –
Damauli section has also improved from 2.58 % to 1.53 %. The result shows that if KHP is
connected then Udipur S/S, Anbu Khaireni S/Ss and Damauli S/S can be run in without
violating the voltage regulation and efficiency limits. The result from Netbas Simulation is
tabulated below.

                   Table.4.21: 30% Substation Load, effect in existing system with KHP
 SNo         Section        Length,       Previous         New Line Previous V New
                            km            Line Loss        Loss     Drop       V Drop
 1           USS to         20            12.29            30.32    1.19       0.21
             DuSS
 2           DuSS to        14.5          79.22            27.24        2.58             1.53
             DaSS
 3           DuSS to        12            7.31             7.15         0.71             0.71
             AkSS
                                    Total 98.82            64.71

Case V: 10 % Loading
After addition of power from KHP in Udipur S/S line losses in three existing section of NEA
has improved. Voltage drop in these sections has greatly reduced. The total losses in these lines
sections increase from 0.01 MW to 0.091 MW. The maximum voltage drop in
Dumre–Damauli section has also improved from 0.82 % to 0.33 %. Unlike other cases the


                                                                                                32
Chapter 4. Results and Discussion


result shows that in lightly loaded condition system performance is better with out KHP. The
result from Netbas Simulation is tabulated below.

                  Table 4.22: 10% Substation Load, effect in existing system with KHP.
 S.No        Section        Length,        Previous         New Line Previous V New
                            km             Line Loss        Loss     Drop       V Drop
 1           USS to         20             1.3              58.17    0.38       0.37
             DuSS
 2           DuSS to        14.5           8.43             32.14        0.82            0.33
             DaSS
 3           DuSS to        12             0.78             0.77         0.23            0.29
             AkSS
                                    Total 10.31             91.48

4.3     Results of LNHP Evacuation System
LNHP to Khudi switching station is about 7 km and this is the only alternative to evacuate
power to grid. Power generation from LNHP is 4.5 MW. This power has to be evacuated to
nearest available grid and that would be Udipur S/S which is 14 km away from Khudi
switching station. New 33 kV, 7 km long transmission line is needed for power evacuation.
From spreadsheet calculation station following results is obtained.
                                    Table 4.23: LNHP evacuation system
 Conductor                    Beaver               Dog              Wolf                 Panther
 Efficiency                   98.65                99.03            99.35                99.51
 Voltage Regulation           1.63                 1.3              1.02                 0.87
 % of transmission loss       1.35                 0.97             0.65                 0.49
 NPV of Investment            16,780               14,163           12,854               12,664
Details of spread sheet calculation are presented in Appendix D. Conductors "Panther" is
recommended because of lowest investment.




                                                                                                   33
Chapter 4. Results and Discussion



                                                                    Conductor and Voltage Optimzation



                             4800


                             4300


                             3800
  Capitalized Cost [kNRs.]




                             3300                                                                                                 Weasel_33
                                                                                                                                  Rabbit_33
                                                                                                                                  Beaver_33
                             2800                                                                                                 Dog_33
                                                                                                                                  Tiger_33
                             2300                                                                                                 Wolf_33
                                                                                                                                  Lynx_33
                                                                                                                                  Panther_33
                             1800
                                                                                                                         Panther_33
                                                                                                          Panther_33
                             1300                                                Panther_33
                                                       Panther_33
                                    Panther_33
                             800


                             300
                               1 Mw                 2MW                      3MW                        4MW            5MW
                                                                         Peak Load [MW]



                                                 Figure 4.4: Conductor Optimization chart for LNHP only

Discussion:

From technical analysis conductors ‘beaver’, ‘dog’, ‘wolf’ and ‘Panther’ all are acceptable but
from conductor optimization chart in Figure 6: for evacuating power of 4.5 MW conductor
‘Panther’ will be economical.

4.4                                 KHP and LNHP Evacuation system
Power Evacuation from Khudi Hydro Power and Nyadi Hydro Power will be more fruitful if
certain portion of power can be consumed locally. The priority is given for local consumption
because such small hydro power plant located very far from grid access. After connecting NHP
and KHP at Khudi switching station the total power will be directly fed to 5 MVA, 33/11
Udipur substation through 14 km long 33 kV new transmission line and excess power after
satisfying local dema nd in Udipur substation will be fed to Dumre Substation through 20 km
long existing 33 kV transmission line and the rest at 132/33/11 kV, Damauli Grid Substation
through 14.5 km long 33 kV existing transmission line. From spread sheet calculation for
power transmission in 33 kV level and 66 kV level from Khudi Switching station to Udipur
Substation following results are obtained.




                                                                                                                               34
Chapter 4. Results and Discussion




                 Table 4.24: LNHP and KHP 14 km long 33 kV transmission line
 Conductor Employed                       Dog            Wolf         Panther             Lion
 Line Length (km)                                    14              14             14           14
 Power to be Transmitted (MW)                         8               8              8            8
 Receiving End Voltage (kV)                      31.27           31.65         31.84        31.91
 Voltage Regulation (%)                           5.24            4.10         3.51          3.31
 Line Losses (kW)                               353.54          237.06       176.77        157.23
 % transmission loss                               3.77             2.56           1.92      1.71
 Line Eficiency (%):                             96.23           97.44         98.08        98.29
 Power Delivered at the load end (MW)             8.62            8.74          8.80         8.82


 NPV of Investment inclusive of Losses,
 O&M and Outages. (NRs.’000)                    78,395          60,528       52,264        50,009


                     Table 4.25: LNHP and KHP 14 km long 66 kV transmission line
 Conductor Employed                           Dog            Wolf          Panther        Lion
 Line Length (km)                                    14              14             14           14
 Power to be Transmitted (MW)                         8               8              8            8
 Receiving End Voltage (kV)                      65.10          65.29         65.39        65.42
 Voltage Regulation (%)                           1.37           1.08          0.93         0.88
 Line Losses (kW)                                88.38          59.27         44.19        39.31
 % transmission loss                              0.97           0.65          0.48         0.43
 Line Eficiency (%):                             99.03          99.35         99.52        99.57
 Power Delivered at the load end (MW)             8.89           8.92          8.93         8.94

 NPV of Investment inclusive of Losses,
 O&M and Outages. (NRs.’000)                   44,876          42,255        41,883       42,185



In this case conductor dog, wolf , panther and lion all can be used because all satisfy the
prescribed technical criteria but if better efficiency and voltage regulation is to be considered
then higher conductor is to be chosen. From conductor optimization chart 66kV conductor
'Panther' is the best option for power evacuation.




                                                                                            35
Chapter 4. Results and Discussion




                                                                         Conductor and Voltage Optimzation



                                       4800


                                       4300


                                       3800                                                                                                   Weasel_33
                                                                                                                                              Rabbit_33
            Capitalized Cost [kNRs.]




                                       3300                                                                                                   Beaver_33
                                                                                                                                              Dog_33
                                                                                                                                              Tiger_33
                                       2800                                                                                                   Wolf_33
                                                                                                                                              Lynx_33
                                                                                                                        Panther_66
                                       2300                                                                                                   Panther_33
                                                                                                                                              Dog_66
                                                                                                                                              Wolf_66
                                       1800                                                                                                   Panther_66
                                                                                                                                              Lion_66
                                       1300


                                       800


                                       300
                                         1 Mw   2MW      3MW          4MW           5MW          6 MW          7MW   8 MW            9 MW
                                                                               Peak Load [MW]


                                                      Figure 4.5: Conductor and Voltage selection for KHP and LNHP



                                                                                                                                            36
Chapter 4. Results and Discussion



Discussion:

Although for transmitting 15 MW power from KSw/S to Udipur S/S 66 kV, conductor
'Panther' is most economical, it is only for transmission line. If 66 kV is chosen the
substation cost will make the NPV of Investment greater than transmission system with
conductor 'Dog'.

Netbas Result:

Netbas Simulation gives us the clear picture of system performance during full load, normal
load and off load. For analyzing existing system performance load flow is carried out for
100% load, 50% load and 10% load of substation capacity. The result is presented below




                            Figure 4.6: KHP and LNHP evacuation system



Case I: Full Load
In full load, i.e. 15 MVA (13.5 MW at 0.9 pf), swing bus i.e. Damauli substation will
generate 6.33 MW including line losses. Power generation from KHP and LNHP are 3.5
MW, 4.5 MW respectively. Maximum voltage drop is at Anbu Khaireni which is 7.95 % i.e.
voltage at Anbu Khaireni is only 30.37 kV. In this case Damauli- Dumre section is heaviest




                                                                                    37
Chapter 4. Results and Discussion


loaded line with 57.35 %. The result of Netbas Simulation for full load case is tabulated
below.
                Table.4.26: 100% substation load, KHP and LNHP power evacuation
 Conductor                              Dog
 Generation at Damauli (slack bus)      6.33 MW, 6.68 MVAR
 Total Generation                       14.33 MW, 7.33 MVAR
 Total voltage independent load         13.5 MW, 6.53 MVAR
 Total Loss in line sections            0.739 MW, 0.971 MVAR
 % of Total Transmission Loss           5.15%
 Max. Voltage Drop and location         7.95%, AnbuKhaireni
 Heaviest loaded line                   Damauli- Dumre, 57.53%

Case II: 70% load
In 70% load, i.e. 10.5 MVA (9.45 MW at 0.9 pf), the swing bus, Damauli substation will
generate 2.15 MW including line losses. Power generation from KHP and LNHP are 3.5
MW and 4.5 MW respectively. Maximum voltage drop is at AnbuKhaireni which is 5.38%
i.e. voltage at AnbuKhaireni is only 31.22 kV. In this case Khudi Sw/S-Udipur S/S section
is heaviest loaded line, 49.91%. The result of Netbas Simulation for this case is tabulated
below.

                 Table 4.27: 70% substation load, KHP and LNHP power evacuation
 Conductor                                         Dog
 Generation at Damauli (slack bus)                 2.15 MW, 6.14 MVAR
 Total Generation                                  10.15 MW, 5.73 MVAR
 Total voltage independent load                    9.45 MW, 4.58 MVAR
 Total Loss in line sections                       0.607 MW, 0.796 MVAR
 % of Total Transmission Loss                      5.98%
 Max. Voltage Drop and location                    5.38%, AnbuKhaireni
 Heaviest loaded line                              Khudi Sw/S-Udipur SS, 49.91%

Case III: 50% load
In this case all three area substations are considered to be operated in half load only. Total
power fed to Damauli S/S is 0.53 MW including losses 0.63 MW in all line sections and the
total load of all substations is 6.75 MW (at 0.9 pf). Power generation from KHP and LNHP
are 8 MW. The maximum voltage drop is 3.76% at AnbuKhaireni, which is 31.76 kV. The
heaviest loaded line is Khudi Sw/S-Udipur S/S, 50.62%.




                                                                                       38
Chapter 4. Results and Discussion


                 Table 4.28: 50% substation load, KHP and LNHP power evacuation
 Conductor                                         Dog
 Generation at Damauli (slack bus)                 -0.53 MW, 5.87 MVAR
 Total Generation                                  7.47 MW, 4.45 MVAR
 Total voltage independent load                    6.75 MW, 3.27 MVAR

 Total Loss in line sections                       0.63 MW, 0.823 MVAR
 % of Total Transmission Loss                      7.8%
 Max. Voltage Drop and location                    3.76%, Anbu
 Heaviest loaded line                              Khudi Sw/s–USS, 50.62 %

Case IV: 30% load
In this case all substations are considered to be running in 30% loading. Total power fed to
Damauli S/S is 3.13 MW including 0.0.724 MW losses in all line sections. Power
generation from KHP and LNHP are 3.5 MW and 4.5 MW respectively. The maximum
voltage drop is 2.2 % at AnbuKhaireni which is 32.27 kV. In this case also the heaviest
loaded line is Khudi Sw/S-Udipur S/S, 52 %.
                 Table 4.29: 30% substation load, KHP and LNHP power evacuation
 Conductor                                         Dog
 Generation at Damauli (slack bus)                 -3.13 MW, 5.67 MVAR
 Total Generation                                  4.87 MW, 3.3 MVAR
 Total voltage independent load                    4.05 MW, 1.96 MVAR

 Total Loss in line sections                       0.724 MW, 0.95 MVAR
 % of Total Transmission Loss                      9.05%
 Max. Voltage Drop and location                    2.2%, AnbuKhaireni
 Heaviest loaded line                              Khudi Sw/S-Udipur S/S, 52.01%
Case V: 10% load
In this case all substations are considered to be running in 10 % loading. Total power fed to
Damauli S/S is 5.66 MW including 0.89 MW losses in all line sections. Power generation
from KHP and LNHP are 3.5 and 4.5 MW respectively. The maximum voltage drop is 0.71
% at AnbuKhaireni which is 32.76 kV. In this case also the heaviest loaded line is Khudi
Sw/S-Udipur S/S, 53.96%.
                Table 4.30: 10% substation load, KHP and LNHP, power evacuation
 Conductor                                         Dog
 Generation at Damauli (slack bus)                 -5.66 MW, 5.54 MVAR
 Total Generation                                  2.34 MW, 2.24 MVAR
 Total voltage independent load                    1.35 MW, 0.65 MVAR
 Total Loss in line sections                       0.89 MW, 1.17 MVAR
 % of total Transmission Loss                      11.125%**
 Max. Voltage Drop and location                    0.71 %, AnbuKhaireni
 Heaviest loaded line                              KH-1 – KH-3, 53.96 %



                                                                                      39
Chapter 4. Results and Discussion


Discussion

Using spreadsheet calculation it is found that, to transmit 6.65 MW from Khudi Sw/S to
Damauli S/S, conductor 'Bear' will make total transmission loss reduced to 4.0 %, if it is
used to transmit power from Khudi Sw/S to Damauli S/S. Loss in 14 km line section to
transmit 8 MW from Khudi Sw/s to Udipur S/S is 44.19 kW, loss in 20 km line section to
transmit 7.55 MW from Udipur S/S to Dumre S/S is 142.43 kW and loss in 14.5 km lo ng
transmission from Dumre S/S to Damauli S/S is 80.11 kW resulting total transmission loss
of 266.13 kW.

Effect in NEA line
Case I: 100 % loading
With addition of KHP and LNHP in Udipur S/S, line losses in three existing section of NEA
has improved; also voltage drop in these sections has greatly reduced. The total losses in
these line sections reduce from 1.32 MW to 0.63 MW. The maximum voltage drop in
Dumre – Damauli section has also improved from 10.29 % to 2.6 %. The result shows that
if KHP and LNHP are connected then Udipur, Anbu Khaireni and Damauli S/Ss can be run
in full load without violating the voltage regulation and efficiency limits. The result from
Netbas Simulation is tabulated below.
              Table 4.31: 100% load, effect in existing system, KHP &LNHP evacuation
 SNo         Section        Length,       Previous       New Line Previous V           New
                            km            Line Loss      Loss     Drop %               V Drop
                                          (kW)           (kW)                          %
 1           USS to         20            170.06         229.9    5.03                 0.45%
             DuSS
 2           DuSS to        14.5          1058.17        309.8        10.29            2.6%
             DaSS
 3           DuSS to        12            97.92          89.41        2.92             2.64%
             AkSS
                                    Total 1326.15        629.11

Case II: 70% loading
After addition of power generated from KHP and LNHP in Udipur S/S line losses in three
existing section of NEA has improved. Voltage drop in these sections has greatly reduced.
The total % of transmission losses in these lines sections reduce from 6.3% to 3.6%. The
result from Netbas Simulation is tabulated below.




                                                                                          40
Chapter 4. Results and Discussion


              Table 4.32: 70% load, effect in existing system, KHP &LNHP evacuation
 SNo         Section                Length,      Previous Line   New Line Loss, kw
                                    km           Loss kw
 1           USS to DuSS            20           75.15           146.57
 2           DuSS to DaSS           14.5         475.6           154.47
 3           DuSS to AkSS           12           43.95           41.46
                                        Total    594.7           342.5

Case III: 50 % loading
After addition of power from KHP and LNHP in Udipur S/S line losses in three existing
section of NEA has improved. Voltage drop in these sections has greatly reduced and with
acceptable limit. The total losses in these lines sections increases from 0.288 MW to 0.63
MW. The result from Netbas Simulation is tabulated below.
              Table.4.33: 50% load, effect in existing system, KHP &LNHP evacuation
 SNo         Section                Length, km        Previous Line       New Line Loss,
                                                      Loss, kw            kw
 1           USS to DuSS            20                36.09               207.77
 2           DuSS to DaSS           14.5              230.59              126.95
 3           DuSS to AkSS           12                21.29               20.45
                                                Total 287.97              355.17
Discussion

After addition of power generated from KHP and LNHP the performance of existing line of
NEA (from Damauli S/S to Udipur S/S) has improved for 70% and 100% loading case but
for load 50% and less performance is worse because all the excess power has to be fed to
Damauli S/S which 34.5 km away from Udipur S/S.

4.5     System with KHP, LNHP and LKHP
There is possibility of coming another Hydro Power 500 m away from KSw/S (Khudi
switching station). This new power plant is Lower Khudi Hydro Plant with capacity of 2
MW. There is only one option for evacuating power from LKHP at KSw/S. The system
performance using Netbas Simulation shows that addition of this power plant will make
existing system inefficient. In full load case total transmission loss is 5.33% and maximum
voltage drop is 7.37% at Anbu Khaireni.




                                                                                       41
Chapter 4. Results and Discussion




                        Figure 4.7: KHP, LNHP and LKHP evacuation system

                    Table.4.34: System Performance with KHP, LNHP and LKHP
 Substation     Total               Total loss in line   % of total     Max. Voltage drop,
 Loading        Generation,         sections             transmission   location
 (%)            MW                  MW          MVar     loss
 100            15                  0.8          1.048   5.33%          7.37%, AnbuKhaireni
 70             10.5                0.901        1.182   8.64%          5.2%, AnbuKhaireni
 50             10                  1.022                8.64 %         3.81 %
 30             10                  1.223                12.23 %        2.48 %

Discussion

From above table, only in full load case existing system looks fine but in lightly loaded
condition the system will be worse. Using conductor 'Lion' in new section KSw/S-USS the
total transmission loss can be reduced to 4.68%.

4.6     KHP, LNHP, LKHP and Chame substation
Chame substation is located in Manang district. In Chame the proposed substation size is
1.5 MVA. This S/S is 50 km away from Khudi switching station. Using transmission
voltage 33 kV with conductor 'dog' the system performance is checked in NETBAS
simulation and is tabulated below.




                                                                                             42
Chapter 4. Results and Discussion




                           Figure 4.8: Evacuation system with Chame load

          Table 4.35 System performances with KHP, LNHP, LKHP and Chame substation
 Substations       Total            Total loss in line % of total          Max. Voltage
 Total loading     Generation,      sections MW        transmission loss   drop, location
 (%)               MW                                                      (%)
 100               15.67            0.75              4.7%                 7.34%, Anbu
 70                10               0.88              8.77%                3.76%, Anbu
 50                10               0.994             9.94                 2.39%
 30                10               1.22              12.22%               2.48%

Discussion:

In full load, only 5.67 MW power is drawn from Damauli S/S and total generation from
three power plants is 10 MW. From NETBAS calculation the highest loss of 1.22 MW will
occur during 30% of total substation loading i.e. 4.05 kW and the transmission loss in
percentage is 12.22 %. Maximum voltage drop of 7.34 % is at AnbuKaireni.

4.7     Load flow analysis of four feeders of Udipur S/S

Power evacuation from Nyadi Hydro Power (NHP) and Khudi Hydro Power (KHP), to
local consumer is possible with four outgoing feeders of 5 MVA, 33/11 Udipur substation.
The four feeders are Besisahar, Bhoteodar, Okhari and MajhGau with total connected load
(TCL) of 1050 kVA, 1950 kVA, 550 kVA and 450 kVA respectively. Load flow analysis
of these feeders using Carl1.0 for peak load time gives the clear picture of local power flow.



                                                                                        43
Chapter 4. Results and Discussion


The result of load flow analysis of each feeder is given below. Detail result is presented in
Appendix F.
                      Table.4.36: Load flow result of four feeders of Udipur S/S.
    Feeder        Total        Total      Active     Reactive    Minimum          Conductor, km
    Name        Connected    Power fed    Power       Power      Voltage
                                                                            Dog      Rabbit   Weasel
                  Load         (kW)        Loss        Loss        (%)

                  (kVA)                    (kW)       (kVar)

 Besisahar        1050        973.59      33.39       39.01       93.56     13.4     6.72     16.8

 Bhoteodar        1950         1660      100.33       80.48       90.21     16.5     15.9     34.9

 Okhari            550        443.68       3.68        2.08       98.9        0        9       18

 MajhGau           450        388.39       5.89        3.33       97.38       0       12       20

Discussion:
From load flow analysis of four feeders it is found that feeder Bhoteodar is worst of all,
having minimum voltage (at farthest end) of 90.21% and total feeder loss of 6.04%. This
feeder uses 16.5 km of conductor 'dog', 15.9 km of conductor 'Rabbit' and 34.9 km of
conductor 'Weasel'. To make local power evacuation more effective and efficient during
peak loading, above four feeders should be managed in such a way so that some part of
loads of feeders Besisahar and Bhoteodar should be shifted to Okhari and MajhGau feeder
for better distribut ion system.




                                                                                                44
Chapter 5. Conclusion and Recommendation



CHAPTER 5

Conclusion and Recommendation
For Power Evacuation study, 3.5 MW Khudi Hydro Power (KHP), 4.5 MW Lower Nyadi
Hydro Power (LNHP) and 2 MW and Lower Khudi Hydro Power (LKHP) are selected
from Lamjung district of Gandaki Zone in Western Nepal. In order to carry power
evacuation study a program is developed in spread sheet. This program results in optimized
conductor and voltage level. This spread sheet program is good only for such transmission
line in which there is no addition of load in future. This program is used to study power
evacuation from KHP, LNHP and LKHP. From Netbas Simulation system performance for
different loading case is studied.
KHP, LNHP and LKHP are located to the north of Udipur S/S. So, one switching station at
Khudi which will be the meeting point of transmission lines from three small power plants
is taken for study. From Khudi switching station to Udipur substation 14 km long
transmission line is used. There are three more existing transmission line sections which are
20 km long Udipur-Dumre joining Udipur S/S and Damauli S/S, 14.5 km long
Dumre-Damauli and 12 km long Dumre-AnbuKhaireni. All of these transmission line
sections have conductor ‘Dog’ and charged at 33 kV. The power evacuated from KHP,
LNHP and LKHP are evacuated to Udipur S/S, Dumre S/S, Anbu Khareni S/S and finally
excess power is evacuated to grid at Damuli Substation.
Existing System
The study shows that the existing system is good only for 50% of total substation capacity
(6.75 MW) considering prescribed transmission loss (4%) and Voltage regulation (10%). It
means the transmission margin is 6.75 MW for Damuli-Dumre transmission section using
conductor ‘Dog’ at 33 kV system. For this section during 30% of total substation loading
available transmission capacity is 2.45 MW. Changing the existing conductor ‘dog’ with
‘wolf’ the transmission margin can be increased to 11 MW.
KHP Evacuation System
Power evacuation from KHP involves 0.9 km long transmission line from KHP to KSw/S
and 14 km long transmission line from KSw/S to Udipur S/S. The 33 kV evacuating system
with conductor ‘Dog’ results in 98.41 line efficiency and 2.16% voltage regulation. For
KHP evacuation only 33 kV system with conductor ‘Wolf’ is best because it has lowest


                                                                                      45
Chapter 5. Conclusion and Recommendation


NPV of Investment. At 100% substations load the voltage regulation and total transmission
loss has improved. Use of 'wolf' conductor in new transmission section is recommended for
better system performance.
KHP and LNHP Evacuation System

Transmission line from LNHP (4.5 MW) is connected to KSw/S through 7 km long
transmission line. For this section with conductor ‘Dog’ and 33 kV system voltage the line
efficiency is 99.03 and voltage regulation is1.3. Conductor 'Panther' is found to be the best
with lowest NPV of investment. Power generation from KHP and LNHP is 8 MW and this
power is jointly evacuated from KSw/s to Udipur S/S. From spreadsheet analysis 66 kV
system with conductor 'Panther' has lowest NPV of investment. But existing system is 33
kV so changing to 66 kV will not be feasible. In 33 kV system, conductor 'Lion' is found to
be the best. As the existing system is using conductor 'dog' so the analysis using conductor
'dog' shows that in 100% substations load the total transmission loss is 5.15% and in 10%
substations load the total transmission loss is 11.12%. NEA line (from Damauli S/S to
Udipur S/S) has improved for 70% and above loading case but for load 50% and less system
performance is worse because all the excess power has to be fed to Damauli S/S which 34.5
km away from Udipur S/S.

For KHP and LNHP power evacuation 33 kV system with conductor 'Lion' is
recommended.
KHP, LNHP and LKHP Evacuation System
LKHP is only 0.5 km away from KSw/S so the 2 MW power generated will be transmitted
to KSw/S and for this sectio n 33 kV system with conductor 'dog' is good. Now, in KSw/S
power incoming from three power generating stations. From spreadsheet calculation in 33
kV transmission system conductor 'dog' is not good because of poor efficiency 95.85%. In
33 kV system conductor 'Bear' has lowest NPV of Investment and in 66 kV system
conductor 'Panther' is best.
KHP, LNHP, LKHP Evacuation System and Chame Load

Chame S/S is located in Manang district and 50 km away from KSw/S. To transmit power
in 33 kV level conductor 'Beaver' is found to be the best option.

Distribution planning of Udipur S/S
The above evacuation study shows that the system performance will be better if more power
can be consumed locally so the planning upto distribution level is very important for best



                                                                                      46
Chapter 5. Conclusion and Recommendation


local power evacuation. Load flow analysis of four feeders are carried out and it is found
that feeder Bhoteodar is worst of all, having minimum voltage (at farthest end) of 90.21%
and total feeder loss of 6.04 %. This feeder uses 16.5 km of conductor 'dog', 15.9 km of
conductor 'Rabbit' and 34.9 km of conductor 'Weasel'. To make local power evacuation
more effective and efficient during peak loading, above four feeders should be managed in
such a way so that some part of loads in feeder Besisahar and Bhoteodar should be shifted to
other feeder so that addition of new load centers can be done.
Finally, the methodology adopted using computer programs for designing as well as
studying the power evacuation from small hydro power plant is also useful for any other
selected small hydro power plant in any remote area of Nepal.




                                                                                     47
                                  References
[1]    NEA GRID CODE, Nepal Electricity Authority, 2005.

[2]    Report on Transmission and System Planning Study, NEA, 2004.

[3]    Planning, Economic and Financial Analysis of Rural Electrification and

       Distribution System Reinforcement for Districts: Gorkha, Lamjung, Gulmi,

       Arghakhanchi and Palpa (Under Package – III, Western Development Region)

       (VOLUME – I), NEA

[4]    Planning, Economic Analysis and Detailed Design of Rural Electrification and

       Distribution system Reinforcement Final Report Part I: (Planning and Economic

       Analysis) For Districts: Parbat, Baglung, Banke and Bardiya (Under Package –

       IV) NEA, September, 2001.

[5]    Paper on, "Simple and efficient method for load flow solution of radial

       distribution networks". D.Das, Birla Institute of Technology and Science; D.P

       Kothari; Center for Energy Studies, IIT; A. Kalam, Victoria University of

       Technology.

[6]    M.V. Deshpande, “Electrical Power System”, Tata McGraw-Hill, 1984

[7]    B. R. Gupta, “Power System Analysis and Design”, S. Chand & Company Ltd.,

       2004

[8]    Badri Ram & D.N. Vishwakarma, “Power System Protection and Switchgear”,

       Tata McGraw Hill, 1995

[9]    William D. Stevenson, Jr., “Elements of Power System Analysis”, McGraw Hill,

       Fourth Edition

[10]   Nepal Electricity Authority, Fiscal Year 2004/5- A Year in Review

[11]   Nepal Electricity Authority Generation, 3rd Issue, August 2005

				
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