Master-slave current control DGs in a microgrid for transient decoupling with mains

Modern power system is envisaged to incorporate microgrids in the power grids to realize efficiently flexible and reliable flow of power by effectively utilizing renewable energy sources and storage systems. The microgrids in such cases thus operate in grid connected and islanded mode. The paper presents a control scheme that is used to implement grid connected and islanded operation of master distributed generation (DG) unit and current control of slave DGs so as to share the load as per their rating, and absorbs the transients arising from load perturbations and DG source switching. Master DG is operated in indirect current control while in grid connected operation and is operated with PWM switching to present a voltage source for slave DGs which are always operated in direct current control mode under central command generating references for different DGs based on sensed voltage and current at different nodes. Simulated results under MATLAB environment are presented to validate the effectiveness of the control scheme.