Comparative Study of Three Phase Grid Connected Photovoltaic Inverter Using PI and Fuzzy Logic Controller with Switching Losses Calculation

Abstract

A comparative study of three phase grid connected photovoltaic (PV) inverter using Proportional-Integral (PI) controller and Fuzzy logic controller (FLC) is presented in this paper. Proposed three phase inverter with single DC source employing three phase transformer for grid connected PV system controlled by using space vector pulse width modulation (SVPWM) technique. PI and FLC are used as current controller for regulating the current. Perturb and observe maximum power point technique (MPPT) is used for tracking of maximum power from the PV panel. Finally total harmonic distortion (THD) comparison made between two controllers for validation of results. Furthermore swithing losses of inverter are also presented. The simulation results are obtained using MATLAB simulink. Keyword:Fuzzy INTRODUCTIONIn the modern scientific world ruled by science, the utilizing of electricity has increased rapidly due to growing of population of the world. Nowadays, most of the research works have focused on PV based power generation due to major reasons such as price of fossil fuel, green house effect and energy available in nature [1]. Actually, solar panel is directly converting solar irradiation in to electrical energy [2]. It is necessary to convert available DC voltage into AC voltage and the converted AC voltage should be sinusoidal with high quality output voltage. For this purpose, multilevel inverter (MLI) is the most suitable choice for converting DC into AC compared to the conventional two level inverters with minimum THD values. MLI's broadly categorised into three main types namely, diode clamped, flying capacitor and cascade [3]- [4]. Three phase MLI inverter using cascaded H-Bridge with independent DC source is presented in the literature review [5]. The above topology, each H bridge require separate DC sources with equal rating and separate DC sources make it system bulky and costlier [6]. Cascade H bridge inverter employing single phase and three phase transformers with single DC input is also presented [7]. This configuration use single DC input and require additional single and three phase transformers for higher voltage level. In accordance with the observation from the references [5]- [7], inverter topology requires more DC input, transformers and switches which result in increased complexity, system size and cost. For maintain grid current as pure sinusodial Proportional-Integral (PI) controller and FLC controllers are used as feedback controller. The PI is maynot satisfactory in controlling various non linear control applications. Moreover the design of its control system is

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