Dunsmuir

A Static Var Compensator (SVC) supplied by Hitachi Energy has been operated since 1993 in BC Hydro‘s power transmission network at Dunsmuir 500/230/132 kV substation on Vancouver Island in western Canada.

The SVC, which is rated at 135 Mvar inductive to 165 Mvar capacitive at 132 kV is situated at the receiving end of a 37 km underwater dual 500 kV cable transmission link feeding Vancouver Island from the mainland AC power network. The circuit distance from the major northern mainland generation to the south-western load is approximately 900 km.

The purpose of the compensator is twofold: to limit overvoltages during normal network conditions and to stabilize the 132 kV system voltage on Vancouver Island in conjunction with major contingencies in the power supply from the mainland.

The bulk steady-state absorption of excess reactive power from the two underwater cables is provided by means of a number of mechanically-switched 500 kV shunt reactors also present in the substation. Considerations revealed that availability would be added to the system by having part of the cable generation (135 Mvar) compensated by the SVC. Also, switching of the shunt reactors is performed from the SVC as part of its steady-state control strategy. This arrangement guarantees that a maximum dynamic reserve will always be available in the SVC in case of network disturbances.