Chapter 3 Operation Strategy

Document Sample
Chapter 3 Operation Strategy Powered By Docstoc
					    Chapter 3




OPERATION CONTROL STRATEGY AND
    SIMULATION OF PV SYSTEM
    INTERCONNECTED WITH EU




                                 1
              Chapter 3



The performance of PV power system interconnected with EU can be
improved through an application of advanced control method. This
chapter introduces an application of an artificial neural network on the
operation control of the PV/EU to improve system efficiency and
reliability. There are two modes of PV system operation. As is said
before.
This chapter focus on the operation control of a hybrid system consists of
PV system accompanied with or without battery storage interconnected
with EU taking into account the variation of solar radiation and load
demand during the day. Different feed forward neural network
architectures are trained and tested with data containing a variety of
operation patterns. A simulation is carried out over one year using the
hourly data of the load demand, insolation and temperature at Zafarâna
site, Egypt as a case study.
                                                                         2
              Chapter 3


 It introduces also a complete computer simulation program of PV
system interconnected with EU. The proposed computer simulation uses
hysteresis current control and instantaneous p-q (real- imaginary) power
theory. A computer simulation program has been designed to simulate
phase voltage of the inverter leg, phase-to-phase voltage of the inverter
leg, current in each IGBT's, DC input current to the inverter, AC output
current of the inverter that injected to the load/grid, load current, grid
current, power output of the inverter and finally power factor of the
inverter.


The following Figure represents the proposed configuration of PV
system which can feed a part of the load demand of 500kW.



                                                                         3
      Chapter 3

                        Boost Converter    Inverter
                                           DC/AC                       Filter
                           DC/DC
                                                                                           0.4/22kV
                       Lb                                                                  500 kVA
                                                                       Lf
                                                          Vinva
                                                  Vinvb
          500 kW
                                  Cb
        PV subsystem                      Vinvc
                       IGBTb

                                  DC                                                     Step-Up
                                  Link                            Cf                   Transformer




                                                                                132/22kV              S3                               S1
                                                                                500 kVA



                                                                  ~
                                                                  EU            Step-Down
                                                                                                           S2


                                                                                Transformer




                                                                                                                                       22/0.4 kV
                                                                                                                Step-Down
                                                                                                                                       500 kVA
                                                                                                                Transformer




                                                                                                                               Load
                                                                                                                              380 V,
                                                                                                                              50 Hz
Fig. 3-1 PV/Load/EU System Block Diagram.
                                                                                                                                               4
             Chapter 3

             3-2 METHODOLOGY OF CONTROL STRATEGY

3-2-1 Control strategy Issue of PV System Connected to EU without
      BS.
         n
      tio
     dia
   Ra




                              DC/DC   DC/AC            Filter

                            Vdcpv


                                                                S3
                                                                            S1

                                                                S2
                                        EU

                                              Output
                    Input




                t
                                                                     Load

 Fig. 3-2 Single-Line Diagram for the Control Strategy of the PV/EU
                              System
                                                                                 5
              Chapter 3

            Power flows in Fig. 3-2 must satisfy the following equations.

             Ppv (t)  Pg (t)  P (t)
                                 L
            Ppv (t)  ONpv * Ppv, out (t)

Where;
Ppv(t)          : The power from PV system, kW.
Pg(t)           : The power to or from EU, kW.
PL(t)           : The Load demand, kW.
t               : The hourly time over one year.
ONpv            : Optimum number of PV system.
Ppv,out(t)      : The output power from one PV module (see chapter 2).
Pg(t) is positive when the PV power is less than the load demand and
negative when PV power greater than the load demand.
                                                                         6
       Chapter 3

       2-2-3        Control Strategy Issue of PV/BS
                   System Connected to EU

The design and installation of this system are more
complicated and expensive, but it is more reliable
than the PV/EU without BS. In this type of intertie
system, the load demand has both PV system, EU
and BS as shown in Fig. 3-3.




                                                      7
             Chapter 3

       n
       tio
   di a
 Ra




                   DC/DC      Controller        DC/AC         Filter

                              1             0
                         S4
                                  Battery



                                                                        S3          S1


                                                EU                     S2
                 Input




                                                     Output
                                                                             Load



Fig. 3-3 Single-line Diagram for the control strategy of the PV/EU/BS
                               System
                                                                                         8
             Chapter 3

                3-3-2 Modeling of a DC/AC Inverter
There are two power inverters topology for utility
interface:-
                                                                                Three-Phase
                                                                               Electric Utility
1- Line Commutated Inverter, LCI.
                                         P dc                           Pinv

2. Voltage Source Inverter, VSI     +
                                                G1       G3      G  5
                                                                Vinva   Lf

                                  Vdc    C              Vinvb

                                                Vinvc

                                                G4      G6       G2
                                    -                                    Cf

                                         DC Constant Frequency
                                         Link PWM Inverter



  Fig. 3-5 Circuit Diagram of the Three-Phase Voltage Source Inverter
                                                                                             9
           Chapter 3

               3-4 APPLICATION AND RESULTS
3-4-1 Operation control strategy of PV System
       Connected to EU.
Figure 3-11 shows the structure of the proposed three layers
NN. X1, X2 and t are the three-input training matrix which
represent electrical power generated from PV, load demand,
and time respectively.




                                                          10
           Chapter 3




                   (1)                  (2)
     Iutputs   W                    W         Outputs

X1                                            Signal to S1 ( 1 or 0)
                                              Signal to S2 (1 or 0)
X2
                                              Signal to S3 (1 or 0)

Time



                         bais


Fig. 3-11 Structure of the Proposed Three Layers NN
        used for Control Strategy of PV/EU.

                                                                       11
                         Chapter 3



            200

                                                                             Pg
            150
                                                                             PLoad
                                                                             Ppv
            100
Power, MW




             50


              0


             -50


            -100
                   1 2   3 4 5 6     7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
                                                Time, Hour



Fig. 3-13 Optimal Operation of the PV/EU to Feed the Load Demand during January (winter)

                                                                                          12
                   Chapter 3



            200
                                                                                       Pg
            150                                                                        PLoad

                                                                                       Ppv
            100
Power, MW




             50


              0


             -50


            -100
                   1   2   3   4   5   6   7   8   9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
                                                        Time, Hour

      Fig. 3-14 Optimal Operation of the PV/ EU to Feed the Load Demand during July
                                         (summer).

                                                                                                    13
 Chapter 3

 Figures 3-16 displays the output of the proposed
 NN of 3+6+3 for month of January using test data.




Fig. 3-17 Outputs of Neural Network for Month of July.
                                                         14
           Chapter 3


           4-3- 2Operation control strategy of PV/BS
                 System Connected to EU

In This Item we insert BS to feed critical load . The
Critical load equal to 18% of a maximum load demand.

A new subroutine computer program has been proposed
and written using Matlab software to simulate the PV/BS
system. The flowchart of this program is shown in Fig. 3-
18. The output of this program has been used to be the
input of NN. The outputs of NN are four trip signals that
send to switches S1, S2, S3 and S4 as shown in Fig. 3-3.
                                                       15
Chapter 3

                                         From End of Program Fig. 2-5




                                                                                                                     Fig. 3-18 Flowchart of the Proposed
                                             For i=1:1:12 month




                                                                                                                        Computer Program for PV/EU
                                             For time=1:1:24 hr




                                                                                                                            Accompanied with BS.
          Batteries are charged
         i.e. S4=1 and the load                        If
                                   yes        0.1< Rad < 0.2 or
              fed from grid
                                                Inverter failure




                                                           No

    Feed the load S1= ON                                                   No                          yes
                                  yes
                                                 P pv(t) > P L (t)                     Ppv(t)= PL(t)

                                                                                  No



                            No
         If SOC (t) >
                                                                         If SOC (t) >            No
      0.8*size of battery
                                                                      0.2*size of battery
                                  Surplus power send to
                                  Battery S4=1, S1=ON
          yes                                                                                   Load feed from EU;
                                                                                       yes       S1=OFF, S2=ON
    Surplus power send to
    EU S3=ON, S2=OFF                                                        Load feed from battery
                                                                                S1=ON, S4=0




                                                                     End                                                                                   16
            Chapter 3

             Figure 3-19 shows the structure of the proposed
three layers NN. X1, X2, X3, X4 and t are the five-input
training matrix and represent state of charge, electrical power
generated from PV, electrical power for EU, load demand and
time respectively.      W
                         (1)
                                         W
                                          (2)


               Iutputs                           Outputs
               X1                                Signal to S1( 1 or 0)

               X2                                 Signal to S2(1 or 0)

               X3                                 Signal to S3 (1 or 0)

               X4                                 Signal to S4 (1 or 0)

              Time




                                   bais
   Fig. 3-19 Structure of the Proposed Three Layers NN used
     for Control Strategy of PV/EU Accompanied with BS.
                                                                          17
           Chapter 3




Fig. 3-11 Operation control Strategy of PV/EU accompanied
          with BS using NN
                                                            18
            Chapter 3

            3-5 SIMULATION RESULTS OF PV/EU
The circuit of Fig. 3-1 is simulated using Matlab/simulink
version 6 as shown in the following Figure.
The output power from PV solar cells array as shown in Fig.
3-27 have been applied to the inverter to feed the load with the
EU. The total power load level is 300 kW with load current
455.8 Ampere for duration 0.3 Sec. After 0.3 Sec., the load has
changed from 300 kW to 100 kW with load current 151.93
Ampere for duration from 0.3 Sec. to 0.5 Sec. as shown in Fig.
3-27.



                                                              19
          Chapter 3




Fig. 3-9 Schematic Diagram of the PV System Connected with EU.
                                                                 20
        Chapter 3




Fig. 3-27 Simulated of Generated Power from PV, Load Demand
                  and EU Power from/to EU.
                                                              21
      Chapter 3
        The following Figures show simulation results of the
          proposed control strategy.




Figure 3-28 Simulated phase voltage of the inverter leg.
                                                               22
Chapter 3




Figure 3-30 Simulated switch current in IGBT's
                                                 23
           Chapter 3




Figure 8 Simulated of inverter current injected to the load/EU

                                                            24
Chapter 3




    Figure 9 simulated of load current
                                         25
Chapter 3




Figure 10 simulated grid current from
               /to EU.
                                        26
Chapter 3




Figure 11 Simulated power factor of the grid.

                                                27
Chapter 3




Figure 12 simulated of the inverter power factor.
                                                    28

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:21
posted:1/5/2011
language:English
pages:28
Description: Chapter 3 Operation Strategy document sample