Improved control strategy for power quality enhancement in standalone systems based on four‐leg voltage source inverters

Abstract

Standalone power supplies using renewable energy resources become a key solution to address both energy consumption and environmental restrictions in remote locations. These standalone systems are weak low-voltage networks, wherein the presence of heavy non-linear and/or unbalanced loads may adversely affect the output voltage quality. Accordingly, four-leg voltage-source inverters play an important role by providing both balanced and unbalanced loads with clean power and balanced output voltage. The reported work proposes a sliding mode control (SMC) along with an iterative learning control (ILC) for harmonic compensation in the presence of critical load conditions such as unbalanced non-linear loads. Indeed, under substantial disturbances, the ILC harmonic compensator smoothly adjusts the input control signal of the SM controller in such a manner to properly reject the disturbing harmonics. The design methodology of the proposed SMC–ILC control scheme is detailed and its effectiveness is validated through simulation and experimental results.