An improved grid tied photovoltaic system based on current conditioning

Abstract

An interconnection of a renewable energy source: photovoltaic generator (PVG) with the power grid is investigated. The interconnection uses the conventional power inverter to link the DC PVG with the AC power grid sides. What is new in the interconnection is that an improved control strategy/technique is proposed to control the switching operation of inverter semiconductor switches. Conditioning the current delivered by the power inverter is enhanced by employing a hysteresis controller. The proposed interconnection avoids the need of installing DC/DC voltage controller and filter that are quite common in the conventional interconnection setups.The proposed current conditioning offers superior features such as: preventing or nearly preventing the penetration of the harmonics into the power grid without the need to install additional power filter commonly found in similar interconnection setups, avoiding the requirement of having controllable DC voltage at the DC side of the power inverter, controlling the power factor level at the point of interconnection with the grid, and relaxing the constraint of synchronization between the inverter output voltage and the power grid voltage prior to the interconnection of the inverter to the power grid.Computer simulations proved the effectiveness of the proposed controller and quite satisfactory results were reached. Keywords: On line grid tied PV system, Inverter current conditioning, Hysteresis controller, Maximum power tracker, Matlab Simulink simulations