Single-phase Z-source-based voltage sag/swell compensator

This paper deals with a type of voltage swell/sag compensator based on single-phase Z-source AC-AC converter. The presented topology employs a pulse width modulation (PWM) Z-source AC-AC converter along with a transformer. During a voltage sag/swell occupation, the proposed system adjusts the adding or missing voltage and maintains the rate voltage at the terminal of the critical load. During normal conditions, the system works in bypass mode. The proposed system does not require any large energy-storage elements such as batteries bank or bulk capacitors. A commutation strategy to drive the AC-AC converter is employed to realize snubberless operation. The operating principles of the proposed system are described, and a circuit analysis is provided. To verify the performance of the proposed system, a laboratory prototype based on TMS320F2812 DSP was constructed with a normal voltage of 110 Vrms/60Hz. Experimental results at 20% voltage swell, 20% voltage sag and 60% voltage sag are shown.