PV-MPPT-based one-cycle control of LV-DC-fed three-leg single-phase STATCOM for high-quality grid current

This paper introduces one-cycle control (OCC) for reduced-DC-voltage-fed three-leg converter for single-phase active filtering and reactive compensation. The proposed power circuit configuration uses six switches (and associated gate drive circuits) and provides a better performance compared to eight-switch version (four-leg) in terms of reduced component count. It has lower semiconductor loss and lower high-frequency distortion in the grid current compared to four-switch version (two-leg). The proposed closed-loop control exhibits grid voltage sensor-less operation with effective compensation of nonlinear/reactive loads (IEEE 519-2022 compatible) and resonance damping of the filter network within the converter. Moreover, the reactive power drawn by the capacitor causes a slight deviation in the reactive power operation. An additional compensation term along with resonance damping term is incorporated in the OCC to overcome this problem. A detailed comparison of semiconductor losses among two-leg, three-leg, four-leg configurations is carried out using PLECS software. The proposed concept is verified through simulation studies.