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Innovative Solutions for High Voltage Substations

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               Innovative Solutions for High Voltage Substations




                              JH van Veenhuyzen



                          ABB South Africa (Pty) Ltd
                      Private Bag X37, Sunninghill, 2157
                   E-mail: john.van_veenhuyzen@za.abb.com




1. SUMMARY

ABB has numerous innovative solutions for high voltage substations up to and
including 765kV for both outdoor and indoor applications.

These innovative solutions include re-engineering of traditional substation
equipment so that circuit breakers, current transformers, disconnectors and
earth switches are combined into a single switchgear module, using the best
technology readily available, based on field proven components.

Benefits from using these switchgear modules include reduced yard space,
minimized civil works and shorter installation time, less commissioning and
maintenance requirements, higher availability and reliability of the substation.

This paper deals with the basic concepts and success stories of these 132kV
switchgear modules for outdoor applications in South Africa therefore
complimenting the meeting theme: “back to basics; successful electricity
distribution practices”.




                                JH van Veenhuyzen - Innovative Solutions for High Voltage Substations
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2. INTRODUCTION



The restructure of the electricity industry will bring significant changes and
pressures on utilities. The new environment will demand a more competitive and
efficient approach.

These changes will demand that the substations be designed, built and
maintained to achieve lower operating and maintenance cost and higher plant
availability.

The utility industry is by nature very conservative. The high capital cost, long
service life and the demand for high plant availability does not encourage risk
taking on new major projects. Introduction of new technology has typically
been progressively.

New technology is usually introduced by installing the new type of plant or
system in a single bay, in less important part of the transmission or distribution
system or where redundancy exist, evaluate it for a couple of years proceeding
on major projects, or alternatively observe the performance of new technology
installed by someone else and when proven use it on own new installations.

The problem with this approach is that major new green field installations only
get built with mature or superseded technology. Yet it is exactly on the new
green field sites, the substations of the future, that we get the maximum
benefits of using new leading edge technology.

However, being prepared to accept a reasonable risk, which is unavoidable if
introducing leading edge technology, brings many opportunities for review and
improvement upon present designs and operating practices.




                                 JH van Veenhuyzen - Innovative Solutions for High Voltage Substations
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3. THE BASIC CONCEPTS

Consider an auto-puffer circuit breaker (Fig 1) and an electromagnetic wound
current transformer (Fig 2) integrated into one unit (Fig 3).




                           +                              =

   SF6 Circuit Breaker      SF6 Current Transformer                   Integrated SF6 Unit
         (Fig 1)                    (Fig 2)                                  (Fig 3)



By displacing the circuit breaker (Fig 3) 90° to the current transformer the
basis of the switchgear model is formed (Fig 4), to which other bay functions
are added.




   Integrated SF6 Unit
         CB 90° to CT
                 (Fig 4)




Add disconnecting contacts to the integrated SF6 unit (Fig 4) and install the
assembly on a motor driven moving frame fixed to a support structure. The
assembly can now either be isolated (Fig 5) or inserted (Fig 6) from the main
circuit.
                               JH van Veenhuyzen - Innovative Solutions for High Voltage Substations
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Earth switches (motorized or manual) are installed on one or both sides of the
supporting frame, to which surge arresters are also mounted (Fig 7).


        Open
                                                                                Closed




               Isolated                                            Inserted
                 Fig 5                                               Fig 6


The combination of a circuit breaker, current transformers, disconnectors,
earth switches and surge arresters represent all bay functions in a single
switchgear module, known as the “COMPASS” (Fig 7).


                  Circuit Breaker                            Current Transformer


      Disconnector                                                      Disconnector


   Surge Arrester


     Earth Switch                                                       Earth Switch




                                                                        Marshalling Kiosk


         COMPASS
            (Fig 7)

                               JH van Veenhuyzen - Innovative Solutions for High Voltage Substations
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Similarly, consider a conventional auto-puffer circuit breaker and GIS
disconnecting and earthing contacts integrated into a single switchgear module
with ring type current transformers fitted to the bushings (Fig 8).




Bushing



                                                                           Circuit Breaker

 CT ring type


  CB Driver
                                                                           Combined
                                                                           Disconnector/
                                                                           Earthing Switch
              (Fig 8)



The combination of a circuit breaker, current transformers, disconnectors and
earthing switches represent all bay functions in a single switchgear module,
known as the “PASS M0” (Fig 9).




          PASS M0
            (Fig 9)




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4. SUCCESS STORIES

4.1 COMPASS (Utilities Application)

The plan was simply to build a 132kV 8-bay switchyard utilizing conventional
switchgear. The existing overhead lines converged at one central point, which
dictated the site location, unfortunately against the side of a hill.

The challenge for Durban Metro Electricity Engineers was to fit the 132kV 8-
bay switchyard into the given area. The layout (Fig 10) indicated below shows
that the land area required was 6056m², and included 5 terraces on which the
switchyard was to be built.




                                                     60% Reduction




  Fig 10                                           Fig 11


The COMPASS switchgear modules installed reduced the switchyard size to
only 2440m², as shown in (Fig 11) and only 1 terrace was required.

The switchyard area required was substantially reduced, i.e. by 60%, and so was
the corresponding savings in civil works, foundations, steelwork, clamps,
installation time, etc …

The photographs below show the switchyard near completion. Most importantly
is the fact that Durban Metro has invested in modern innovative technology
rather than in civil works, foundations, steelwork, clamps and installation time.




                                JH van Veenhuyzen - Innovative Solutions for High Voltage Substations
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4.2 PASS M0 (Industrial Application)

ABB has recently commissioned a 6-bay outdoor 132kV switchyard using the
PASS M0 switchgear modules for Hillside Aluminium in Richards Bay.

The project required the introduction of 3 x 132kV incoming line bays and 3 x
132kV 110Mvar PFC feeder bays installed outdoors between the existing Eskom
termination towers and the existing 132kV GIS incoming line bays as indicated
below (Fig 12).

                                            + 50m


                                                            Existing Eskom
                                                          Termination Towers




   + 39m

                                                                                      New PASS M0
                                                                                     Line Feeder Bays




                                                                                    New PASS M0
                                                                                   PFC Feeder Bays




                             Existing GIS Building
                                                                                     (Fig 12)




Due to the tight space requirements, high industrial/marine pollution, transient
recovery voltages, reliability and availability specified by Hillside Aluminium, the
170kV PASS M0 was the only switchgear that could fulfill their tough criteria.

The PASS M0 was fitted with a staggering mechanism mechanically displacing
the phases by 60º enabling zero voltage phase switching for the PFC banks.
The control and protection panels where also fitted with ABB’s “Switch Sync”
relay to detect voltage zero before the switch in procedure commenced.


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The photographs below show the switchyard near completion. Notably, Hillside
Aluminium has invested in modern innovative technology with the highest
possible availability and reliability available today for this difficult outdoor
application.




5. CONCLUSION

The major impacts of the new technology have been significant changes to
design practices. Bays are pre-fabricated, pre-wired and pre-tested in the
factory before shipment to site.

A reduction in the number of drawings required, new and more cost effective
site layouts, radical changes to bay layouts, new busbar arrangements, less
cabling, abandonment of old requirements which were no longer seen as
essentials.

A different approach to switching, isolation and access should be accepted as
well as radical changes to maintenance requirements and practices as
maintenance are based on the concept of remove for repair and insert
replacement components.

Therefore in conclusion, a break with the past provides a powerful base for
thinking of solutions for the future.




                                JH van Veenhuyzen - Innovative Solutions for High Voltage Substations

				
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