Double Closed Loop Control and Analysis for A Static Synchronous Series Compensator

The paper describes the theory, the modeling technique, control scheme of static synchronous series compensator. Two control modes which maintain a desired voltage on the DC storage capacitor C without energy storage system and with energy storage system are proposed from the control performance view of the device. The synchronous rotating dq frame and SVPWM technique are used in control system of SSSC. The utilization of DC link voltage and output voltage of series converter are increased by SVPWM technique. Based on park transformation, a double closed loop decoupled control scheme of SSSC in d and q-axis is designed, which eliminates the dynamic interaction between active and reactive power flow through the line. In addition, in control system, the response of the inner current loop is much faster than response of the outer voltage loop, which ensures that input current follows input voltage and improves dynamic performance of SSSC. The advanced control method is rapidly implemented by a digital signal processor (DSP). Simulation and experimental works are done to verify the effectiveness of applying such control strategy in SSSC