Simulation of Effects of Using Capacitor for Reactive Power (VAR) Compensation on Electrical Power Supply Quality

Abstract

Electrical load in industrial sector is mainly inductive that requires large amount of reactive power supply. Large reactive power consumption may give problems to electrical power supply and distribution system such as lower power factor, higher power loss for both electrical power distribution system and all electrical power devices connected in it, and higher voltage drop in electrical power distribution system. Therefore, a measure known as reactive power compensation (VAR compensation) by connecting power capacitor as reactive power source need to be taken. However, VAR compensation measure may give other problems to the electrical power supply and distribution system. This paper describes effects of using capacitor for VAR compensation to the quality of electrical power supply and distribution system based on simulation run with Matlab Simulink software. Three different kinds of VAR compensation method are analysed i.e., connecting a small capacitor for each inductive load, connecting a large capacitor at the electrical power supply side in which its reactive power flow is controlled by SVC (static VAR compensator) method and connecting a large capacitor at the electrical power supply side in which its reactive power flow is controlled by TSC (thyristor switched capacitor) method. Analysis results show that all the three VAR compensation methods successfully improve or increase power factor of the electrical power supply and distribution system close to unity. However, both the SVC and TSC VAR compensation methods increase harmonic content of voltage and current of the electrical power supply and distribution system as indicated by its high total harmonic distortion (THD) value. On contrary, the VAR compensation method by connecting a small capacitor for each inductive load brings no effect on increasing of harmonic content of voltage and current of the electrical power supply and distribution system.