Voltage Control and Harmonics Elimination of Microgrid Using Back-to-Back ElectricSpring

This paper presents a voltage control scheme of critical load in microgrid structure in islanded condition. For this voltage control operation, a new control strategy has been proposed. A 25Kw SEIG system supplies power to critical, non-critical, and non-linear loads in this microgrid structure. Two three-phase inverters connected back-to-back to achieve a constant voltage profile across the critical load. One three-phase inverter is connected in series with the non-linear load to work like an Electric Spring (ES). Another shunt-connected inverter supports the series inverter by maintaining constant DC voltage across the DC link. Along with that, the shunt inverter eliminates the system harmonics. Various test cases, like non-linear load' behaviour on both critical and non-critical load sides have been simulated in MATLAB/Simulink environment showing the efficiency of the proposed controller. In each case, the proposed controller is found to eliminate the harmonics and maintain constant dc link across the back-to-back inverters. Hence, the proposed scheme can be a solution for voltage control in microgrid structure during an islanding condition.