Reciprocal effects of the distorted wind turbine source and the shunt active power filter: full compensation of unbalance and harmonics under ´capacitive non-linear load´ condition

Available compensating algorithms for shunt active power filters (SAPFs) and unified power quality conditioner perform somehow improperly in practice under certain circumstances. Typical examples could be any distorted `non-linear loads´ showing low impedances at certain frequencies; also, there are technological limitations for the SAPF in modulating switching frequencies, including microcontroller processing speed, the employed control and modulation techniques, delays and so on. This study proposes an advanced universal power quality conditioning system (AUPQS) to fine tune the available solutions for generating purely sinusoidal wind turbine-end currents under both distorted-unbalanced load-terminal voltages and non-linear load conditions (capacitive loads leave much worse consequences than those of the inductive). It is shown that both series and SAPF are capable of full compensation of microgrid by the SAPF using the advanced generalised theory of instantaneous power. Meanwhile, the resultant source currents could be somehow non-sinusoidal. However, the proposed AUPQS will be able to fully eliminate the consequence of voltage asymmetry and unbalanced waveforms on the SAPF, generated because of the wind turbine operation by performing certain corrections on these solutions. Moreover, an independent single-phase rectifier is proposed at the load-end to regulate DC-link voltage. Effectiveness of the proposed AUPQS is confirmed by Simulink simulations.