Grid Integration Issues of Distributed Generations

Abstract

Paucity in the energy scenario had made conservation of energy an essential issue. Usage of Renewable energy sources (RES) is increasing in the present era, which calls for green and clean energy sources. RES includes various forms viz., solar energy, wind energy, geothermal energy etc. but the most favored are the solar and wind energy. Most RES are intermittent in nature. To integrate RES to a utility grid is a quite challenging task, to track the maximum power point (MPP) of a consistently irradiated PV system is important and is yet another challenge. Of all the available methods in the MPPT context the Perturb and observe (P & O) method and incremental conductance method are the widely used techniques. In this project the P & O method is implemented for tracking the MPP. The tracking system conventionally is supplied the PV array voltage and current to track the MPP. In this thesis instead of having a sensor for measurement of the solar array current, it is estimated or observed with a sliding mode observer. The observer is based on sliding-mode and is constructed from the dynamic equations of the considered system viz. a single phase grid connected Photovoltaic system that has a Photovoltaic module and a single-phase H-bridge inverter. The solar array current is observed by the known values or measured values of the array voltage and inductor current. The current estimation is governed by the sliding mode observer gain, as we increase the value of the gain chattering problems come into being. The estimated value almost follows the original current and hence, is used to track the MPP. In this thesis at first the methodology of grid integration of distributed Photovoltaic systems are studied and simulated. And then an observer based on sliding-mode theory, the MPPT control was developed.