New Generator and Shunt Reactive Power Control Based Secondary Voltage Control Approach

Abstract

In Malaysian Transmission System (TNB), most of the voltage control and reactive power resources are manually controlled. For better and optimal voltage control of the TNB power system network, new secondary voltage control (SVC) system that coordinates the voltage and reactive power control of continuous and discrete control devices has been developed. The primary goal of new SVC system based control strategy is to control the bus voltage at the selected pilot buses to follow the optimal reference values as updated by TVC system, and the secondary goal is to provide a high-side voltage set-point for power plant control to equilibrate the reactive power distribution among all control generators in each control zone to enhance the security of the power system. In this approach, the coordinated SVC system is designed to control not only the generating units, but also the reactive power devices including transformer tap-changers as well as switched shunt capacitors and reactors. The selection of reactive power devices for control is implemented through substation voltage control (SSVC) system, which then will be the input to the SVC system. If the target voltage of the pilot buses is followed, the power plant voltage controller (PPVC) will be able to equilibrate VAR among the participating power generations to enhance the power system security by increasing the MVAr reserve for dynamic control. Simulation studies based on PSS/E load flow and closed-loop real-time power system simulator using TNB snapshots shows that the new coordinated SVC system approach is able to provide more consistent voltage control actions and has produced great control actions for flatter voltage profile, reducing transmission system loss and increasing VAr reserve margin as compared to the existing SVC approach that is only focused on generator control as the main source for the voltage control.