Control of DC-capacitor Peak Voltage in Reduced Capacitance Single-Phase STATCOM

This paper discusses the design and control of a single-phase STATCOM with reduced dc capacitance. It is first demonstrated how operation with reduced dc capacitance and large dc voltage oscillations can be possible without increasing the maximum dc voltage, as long as only operation for reactive power injection is required. Then, a method for dc peak voltage control is proposed, based on adaptive filters for dynamically detecting the average value and the amplitude of the dc voltage oscillations. It is demonstrated by simulations and experiments that the presented control strategy can be effectively utilized to regulate the peak voltage in the dc capacitor under various operating conditions.