Power Quality Improvement from Grid Connected Renewable Energy Sources At Distribution Level Using Fuzzy Logic Controller

Harmonic pollution of the power supply system has risen significantly in recent years due primarily to an increase of non-linear loads connected to the utility through residential, commercial and industrial customers. Power supply voltages become distorted due to the high level of undesired harmonic current drawn from the utility. Additionally, drops in fundamental voltage are caused by the interaction between the reactive current and network impedances. Renewable energy resources (RES) are being increasingly connected in distribution systems utilizing power electronic converters. This paper presents a novel control strategy for achieving maximum benefits from these grid-interfacing inverters using the closed loop fuzzy logic control, when installed in 3-phase 4-wire distribution systems. The inverter is controlled to perform as a multi-function device by incorporating active power filter functionality. The inverter can thus be utilized as: power converter to inject power generated from RES to the grid, and 1) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. All of these functions may be accomplished either individually or simultaneously. This new control concept is demonstrated with extensive MATLAB/Simulink .Finally the proposed scheme is implemented using conventional DC link controller and intelligence controller.