Flexible Third Harmonic Voltage Control of Low Capacitance Cascaded H-Bridge STATCOM

The recently presented low-capacitance cascaded H-bridge (LC-CHB) STATCOM presents a compact and cost-effective STATCOM solution, which varies the averaged dc voltage according to the compensated reactive power during operation to intentionally enlarge the low-frequency dc voltage ripple and meanwhile keep the dc voltage within the allowed range. This letter further optimizes the operational performance of LC-CHB STATCOM by using a flexible third harmonic control method, which could reduce the voltage stress on semiconductors during operation and the switching losses in consequence. Experimental prototype verified the performance of the proposed control strategy.