INTRODUCTION TO MICROGRID AND SECONDARY CONTROL OF MICROGRID

Abstract

Micro-Grid provides a replacement of combining Renewable Energy Resources(RESs) and Distributed Generators (DGs) into power systems in an efficient manner. For the deployment of a MG, its stability and control issues are to be taken care of. Various efforts are being made to design more efficient control methods in different types of control types and different types of protection programme to make a reliable, safe, and economical operations of MG which is operated in either grid-connected mode or islanded operation mode. In the first stage of implementation, the PV system is made, and its MPPT control method is employed for taking out the maximum power out of a solar panel module. The DC link is connected to a battery or energy storage device via a bidirectional converter for maintaining constant DC bus voltage if solar energy is not sufficient due to changes in irradiance. In the final stage of implementation in grid-connected mode to have a constant DC link voltage for balanced and stable system control strategy is employed on the inverter side so that when the power generated by the solar panel is high, it will try to increase the DC bus link voltage, but the controller will increase the inverter current so that DC bus link voltage remains constant. And also battery management system is used so that charging and discharging of different ESUs depend on their SOC values. In other words, the control operation is based on ESU’s state of charge.