Improvement of load bus voltages considering the optimal dispatch of active and reactive powers

Abstract

This paper presents a simultaneous active and reactive power/voltage dispatch methodology using a mixture of continuous and discrete control variables. The continuous control variables are active power and reactive power/voltage magnitudes of generator buses, while the discrete ones are transformer-tap settings. The Lambda iteration based economic dispatch is used to minimize the fuel cost and active power dispatch among the generators. During this process, the voltage magnitude of load buses may move away from the desired value. The genetic algorithm is applied for optimal reactive power/voltage dispatch among generators and determination of tap settings of under load tap changers (ULTCs). This results in globally improvement of voltage regulation of load buses. Considering the fact that the reactive power/voltage of generators are continuous variables while the transformer tap settings are discrete variables, a method is proposed to combine these variables into one suitable chromosome. The IEEE 30-bus test system is used to illustrate the effectiveness and feasibility of proposed approach.