Design and Development of Small Signal Model of Distribution STATCOM for Power Factor Improvement

The DSTATCOM (Distribution STATic synchronous COMpensator) is being increasingly popular in power system applications. In general, compensation of reactive power in a power distribution network of a power utility and industry plays a major role in reducing distribution loss and maintaining constant distribution voltage. A simple transformation and steady state and transient analysis are achieved to characterize the open loop system. A control scheme of the DSTATCOM has been proposed without controlling DC-link voltage. The small signal scheme controls the phase angle as well as modulation index of the switching pattern and with small perturbation of reference current (reactive current of load), the DC voltage nearly remains constant. On variation of DC-link voltage, the spike and overshoot of the responses have been studied and suitable DClink voltage has been selected. Accordingly, the parameters of the DSTATCOM have been designed. All responses are obtained through MATLAB/SIMULINK tool box and presented here for clarity of the control strategy.