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Customer Success Story

Chénier, Canada

SVC to stabilize a large 735 kV transmission system in Canada

In Canada, Hydro-Québec is operating a total of eight Static Var Compensators (SVC) in its 735 kV transmission system, supplied by Hitachi Energy. The 735 kV grid transmits a total of 15000 MVA of environmentally friendly hydro power over six lines from the generating stations along La Grande Rivière at James Bay down to the Montréal area some 1000 km to the south.

Two of the SVCs went on line in 2011 at the Chénier 735 kV substation close to Montréal, each rated at 300 Mvar inductive to 300 Mvar capacitive (-300/+300 Mvar). Their purpose is to:

  • Regulate and control the 735 kV voltage under normal steady-state as well as contingency conditions;
  • Provide dynamic, fast response reactive power following system contingencies such as network short circuits and line and generator disconnections;
  • Enhance the first swing stability by maintaining system voltages during large disturbances.

Two SVCs were commissioned at Chamouchouane 735 kV substation in 1990, each rated at 110 Mvar inductive to 330 Mvar capacitive, and later extended to -330/+330 Mvar. And finally, four SVCs, each having a dynamic range of 110 Mvar inductive to 330 Mvar capacitive, formed a turn-key commitment comprising two units commissioned in 1984 at La Vérendrye 735 kV substation and two at Chibougamau in 1985. The purpose of the compensators is two-fold:

  • Stabilize the voltage during normal operating conditions;
  • Maintain the system stability during network disturbances.

In order to achieve the greatest amount of flexibility of operation, the two SVCs in each station can work either independently of each other or under a joint control mode.

Main data
Commissioning year: 2011
Controlled voltage 735 kV
SVC rating -300/+300 Mvar
Control system Three-phase voltage control by means of a voltage regulator
Thyristor valves Water cooled, with indirect light firing
 Ambient temperature range -40°C to +40°