Optimum Reactive Power Dispatch Using Differential Evolution for Improvement of Voltage Stability

Reactive power dispatch (RPD) is one of the important tasks in the operation and control of power system. This paper presents a Differential Evolution (DE) - based approach for solving optimal reactive power dispatch for voltage stability enhancement. The monitoring methodology for voltage stability is based on the L-index of load buses. The objective is to minimize the sum of squares of the L-indices subjected to limits on generator real and reactive power outputs, bus voltages, transformer taps and shunt power control devices such as SVCs. The proposed algorithm has been applied to IEEE 30-bus system to rind the optimal settings of reactive power control variables. The optimal reactive power dispatch results are obtained using DE and are compared with and without Flexible AC Transmission System (FACTS) device such as Static Synchronous Series Compensator (SSSC). It is shown that the objective function value is less with the consideration of SSSC device.