Adoption of 132kV standalone GIS with condition monitoring system for shunt reactive load switching

Reactive power compensators such as capacitor banks and reactors are switched in/out on a daily basis, subjected to the system conditions. If the switching is done via the Circuit Breaker (CB) in the 132kV GIS Switchboard, the CB will suffer from continuous electrical and mechanical stress, increasing the probability of CB failure and affecting the reliability of the supply system. As a result, frequent overhauls/refurbishments will be required to maintain the condition of CB in a reliable state. In many cases, this will require shutdown of the switchboard. These maintenance requirements and reliability risks can be mitigated by adopting a standalone Gas Circuit Breaker (GCB) designed for frequent and large number of switching. In the event of GCB failure, the faulty GCB can conveniently be replaced without busbar outage. However, the GCB is constraint by its large footprint and safety concerns over access to the energised equipment. The standalone GIS is introduced in lieu of the GCB to provide a solution where constraints make it difficult to use the GCB and with the original benefits. Since 2010, two modules of standalone GIS have been commissioned for use in CLP Power (CLPP). System reliability can be further enhanced through the close monitoring of CB condition of a standalone GIS. A trial on-line monitoring of the GIS including the CB condition is to be implemented at a trial Digital Transmission Substation in Q3 2012 to pave way to support smart grid operation in future. This paper discusses the adoption of standalone GIS for shunt reactive load switching in CLPP 132kV transmission network, including its design philosophy and the advantages for the adoption. It also discusses different topologies of standalone GIS installed in CLPP and a trial of on-line condition monitoring on a Standalone GIS unit as part of