Reactive power simulation and control for electric utilities

This paper describes reactive power (var) flow and its effect on power system control and operation. In particular, an Automatic Var Control computer program is described which is being implemented in the Energy Control Center of a Canadian utility. This program will send control signals to power system devices in order to eliminate or at least minimize voltage violations. The control devices include generating units, transformers, and shunt capacitors. A linear programming algorithm is employed to determine the amount and placement of control action based on linearized incremental relationships between voltage and var flow.