On varying capacitive SVC based on PLC controlling PWM

With the increasing of dynamic inductive load in power system, the research of adjustable capacitive reactive power compensation equipments in recent years has become a hot spot. Two capacitors with different value can be continuously adjustable in a certain range under the control of switching device whose state is controlled by PWM wave. This paper introduces the basic principle of PWM continuously varying capacitance, and completes the formula´s calculation of equivalent capacitance C. Then, we build a simulation platform using MATLAB, and analysis its characteristic of varying capacitance and effect of reactive power compensation. This article proposes a hardware structure in controlling capacitance based on PLC. In experiment, we establish a test reactive power compensation equipment with the PLC as the core of controlling, and experiments result verifies the theory well.