CONTROL STRATEGY FOR CURBING VOLTAGE REGULATION ISSUES CAUSED BY INTERMITTENCY OF RES IN A RADIAL MICROGRID

Abstract

With the development in power electronics technology, distributed energy generation using renewable sources of energy such as PV, wind turbines etc. are gaining importance in recent times. Generation of electricity using renewable energy sources can yield power in KW scale or in MW scale. Energy generated using RESs is used to supply power to localized loads at the distribution level. This helps relieve burden on conventional power plants and thus improve reliability of the utility system. With the increase in penetration of distributed generation in recent times it led to the development of microgrids which consist of low voltage distribution systems having distributed energy sources alongwith storage devices. Due to intermittent behaviour of DGs using RESs, it becomes a challenging task to integrate them with the utility grid. Different types of microgrids such as AC microgrids and DC microgrids operating in various modes such as islanded mode and grid – connected mode have been discussed in detail. Due to the operation of microgrids in islanded mode and grid – connected mode, power electronic engineers face various technical challenges; low inertia of interfacing inverters, power quality related problems, design of protection devices being the most prominent ones have been discussed in detail. This work gives a detailed description of the mathematical tools and techniques used for the development of control algorithm for current-controlled Battery Energy Storage System (BESS) connected in shunt with the load. Control algorithm is developed for curbing voltage regulation issues caused due to intermittency of RES in a radial microgrid. Conventional droop control is explained in detail and is being implemented in the control algorithm for the creation of virtual inertia following a specific droop rate. MATLAB/Simulink model of the proposed system configuration in which BESS is connected in shunt with the load alongwith RES based DG is discussed in detail. Simulation results of the proposed radial microgrid operating in grid – connected mode for various types of loads are analyzed and are presented in this work.