Voltage control strategy of distribution static synchronous compensator without current sensor

D-STATCOM (Distribution-STATic synchronous COMpensator) improves voltage quality by exchanging reactive power with power grid. The control strategy of using D-STATCOM to maintain and balance the voltage of common connecting point is emphasized. The power exchange in D-STATCOM system is analyzed based on the instantaneous power theory and the relationship between the positive/negative sequence component of output voltage and the output current is derived. The voltage control strategy without inner current loop is presented, which does not need current transducer and corresponding conditioning circuit. Compared with the traditional way of outer voltage loop plus inner current loop, the proposed control strategy is of simple structure and easy design. The voltage controller consists of positive and negative sequence voltage controllers. Simulative and experimental results show that the voltage of common connecting point is stable and balanced simultaneously. This project is supported by Hunan Provincial Natural Science Foundation of China (07JJ6081).