Development of Anti Islanding Schemes for Photovoltaic Based Microgrid System

Abstract

Growing population and rising power demand require supplementing conventional energy sources with that of conventional sources. Renewable energy sources (RES) based distributed generators (DGs) are used as such secondary sources. The benefits of RES based DGs include better power supply reliability, on-site power generation, no transmission loss, and no air pollution. The RESs may include solar panels, wind turbines, diesel generators, etc. individually or in combination forms of any of these. Conventional generators are connected to high-voltage transmission grids whereas these DGs are usually connected to low-voltage distribution grids as in residential and commercial applications. Microgrids are local electrical grids that can be disconnected from the main grid and can work in isolated mode. Microgrids may diverge from a single-customer microgrid to a full-substation. They are very useful in dangerous and destructive environments like the black-out of the main grid. Microgrids can operate both in grid mode and islanding mode effectively. RES based microgrids are gaining faith continuously as they are capable of local generation-local consumption as well as support the main grid to recover from extreme states. Some of the potential challenges in grid-tied mode operation are voltage and frequency regulation, power quality, system stability, synchronization, and islanding. Islanding refers to the situation where the grid is cut off from the main grid, but the microgrid and load are still intact in this isolated network. The loads are continued getting a supply that can be fatal. So, the islanding condition needs to be detected and the microgrids are to be switched off. Then, the loads are delinked from the supply. The analysis of islanding conditions is the major topic of this research endeavour. Generally, the grid side circuit breakers get opened due occurrence of any defect in the grid side, isolating the rest of the system. In this islanding state, there is a power mismatch between the load and the generation