WG A3.28 Switching phenomena and testing requirements for UHV & EHV equipment

Background :

Major factors in the recent, and ongoing, development of ac transmission systems up to 1200kV have been the environmental and economic scrutiny to which utilities are subjected. This has created a need to optimize proposed infra-structure whilst maintaining expected levels of system performance. In response to these demands, the design of compact, cost effective systems for bulk, long distance power transmission at the highest system voltages has progressed significantly in recent years.

As an example, modern technologies in conjunction with advanced simulation methods have contributed to the specification of switching impulse withstand levels for 1100kV projects which only exceed those specified by IEC at 800kV by a small margin. This approach provides excellent opportunities for optimizing both the size & cost of UHV equipment but may also have implications for the design of lower voltage systems such as those employed at 420kV/550kV.


Scope :

Following on from the work published by WG A3.22, the new WG addresses specific aspects of UHV switching phenomena, equipment & testing in greater depth. The theoretical aspects and simulation of specific phenomena will be explored and correlated with service experience from existing systems and from early UHV projects as this becomes available. The WG undertakes a benchmark study of switching requirements based on model UHV networks reflecting the utilities practices and policies (China,India,Japan, etc.) for UHV and EHV system configurations surveyed by the WG A3.22. The relationship between existing specifications, theory and service experience analyzed such that improved recommendations for specification & testing can be developed (in support of SC17A).

A particular role of the new WG is to gather information relating to field experience and switching behaviour during and after commissioning of UHV transmission in China, India and Japan and to compare this with existing information from other sources & studies.

In addition the WG investigates the scope for applying optimized design techniques, as applied for UHV, to lower voltage transmission systems (particularly 420/550kV).

The WG focuses on activities associated with UHV and EHV systems and switching equipment. It actively cooperates with other SCs and with IEC TC17.