Design and Analysis of Load Switching Mechanism Using Sub-Microgrid Approach

Microgrids are evolving as a solution to exhausted, overburdened conventional power systems. However, several issues related to inverter interfaced microgrids exist. These issues include intermittency of renewable energy based generations sources which leads to the voltage, frequency mismatch that eventually disturbs the grid quality and affect the loads. This paper develops a sub-microgrid approach i.e. Sub-grid within a microgrid using load switching mechanism (LCM). The LCM switches the load from one distributed generation to the other using central controller. The loads are divided into three groups i.e. Heavy loads, light loads and critical loads. Two distributed generators, solar power and wind power along with the central storage are the generation sources. The central controller checks the power generation from the two sources and connects the heavy and light loads to the distributed generator appropriate for the loads. In case of no power available from any distributed generators, demand response program is initiated to supply the critical loads only. Three scenarios have been tested based on the frequency deviations during transition state from one source to the other source.