A Sensorless Asymmetric and Harmonic Load Compensation Method by Photovoltaic Inverters Based on Event-triggered Impedance Estimation

Low voltage distribution grids face substantial challenges in terms of power quality, efficiency and grid utilization that can affect both utilities and consumers. This work proposes a controller for grid-tied photovoltaic (PV) inverters, enhanced with advanced functionalities, to compensate current asymmetries and harmonics in low voltage distribution grids. The proposed method relies on the estimation of the grid impedance that is utilised to approximate the current imbalance and harmonics caused by nearby loads. As a result, the need to measure the asymmetries and harmonics of nearby loads is alleviated, allowing a plug-and-play operation of PV inverters for the provision of phase balancing and harmonic compensation services. The effectiveness of the proposed method is experimentally validated in a laboratory-scale low voltage distribution grid with prototype inverters, in which PV inverters estimate and compensate current imbalance and harmonics of nearby loads. The experimental results indicate benefits in terms of power quality, reduced energy losses and effective utilization of distribution grid capacity.