Automatic On-line Controller for Coordinated Slow Voltage Control

This paper proposes an automatic discrete slow voltage controller, which is motivated towards implementation in the western Oregon system in Pacific Northwest. This part of the system is far from generators and the main voltage control devices are capacitor banks, reactor banks and LTC transformers. The project pursues a model-based approach for selecting the discrete control actions for on-line implementation. Effects of control devices are evaluated by adaptive local computations. The control objective at present is to keep the voltages within constraints with minimum switching cost. A robust control strategy is proposed to make the control feasible and optimal for a set of power-flow cases that may arise from load forecasts and from uncertainty in state estimation models. Studies conducted for spring 1998 WSCC cases indicate that the proposed control methodology is quite effective in deciding switching of capacitor banks.