Dynamic security dispatch: Basic formulation

This paper presents preliminary results on a direct method for dynamic security dispatch in large power systems. The usual indirect approach starts with an operating point chosen to give optimal economy; then contingency testing using simulation indicates adjustments which may be needed to ensure adequate transient stability after the most likely faults. The nature of the adjustments is derived from “intuitive feel” for the system. Using a model given by Bergen and Hill [1], distribution factors are presented for systemmatically improving transient stability with variation of bus powers, line impedances and bus voltages. By incorporating a stability index into the cost function for economic dispatch, there can be a tradeoff between the requirements for economy and stability in choosing an operating point. The method could be adapted to either planning or on-line scheduling to ensure adequate dynamic security. The application of the approach is demonstrated on a 5 bus example system.