Decoupled Controller for Simultaneous Harmonic and Unbalance Compensation in a multifunctional RES system connected to a LV Distribution Grid

There is an increasing concern over power quality with more distributed non-linear loads leading to unbalance and voltage harmonics in low-voltage (LV) grid. The traditional way to improve the power quality in the system is to adopt passive filters or centralized active power filters. Today, many renewable energy-based sources (RESs) are connected to the grid with interfacing converters which can provide harmonic and unbalance compensation. This paper deals with a decoupled controller for simultaneous harmonic and unbalance compensation in a multifunctional smart RES unit. It works on a novel hybrid approach which does not require point-of-common-coupling (PCC) voltage harmonic extraction, multiple phase locked loops (PLLs) or knowledge of distributed load currents. The active power from RES contain both positive and negative sequence current components for improved voltage unbalance compensation. Simulation study for a single RES unit connected to a LV grid with non-linear loads is carried out in PSCAD and results are presented.