Improved emergency control strategy with optimal control time based on dynamic security region

Through a mount of simulations of power system emergency control, it is confirmed that action time of emergency control affects the transient stability of power system. This paper introduces control time component in the consideration of the existing emergency control model which is based on the dynamic security region(DSR). This paper quantifies the degree of system instability parameter after shedding loads and tripping generators at certain time when fault occurs. It puts forward a improved emergency control method with optimal acting time. This method can reflect the condition of the instability of power system and give the optimal moment of concentrated loads shedding and generators tripping. Simulation on IEEE 4-generator 11-bus system shows that taking emergency control at the improved method can decrease the vibration of the system, and minimize the cost of emergency control strategy.