Voltage Control for Three- Phase Inverter Based Distributed Generation under Grid Disturbances

The recent trend of distributed generation leads to several issues regarding power quality and energy efficiency. To meet the increased demand of electricity services and to increase service quality the current power grid structure should be controlled in such a way that distributed generation could be easily connected to it. The various services are becoming challenging concern to elegantly integrate distribute generation to the grid. One of these services is voltage control which provides support to the voltage under grid fault conditions. During voltage sag condition continues power supply should be provided to grid. According to grid code requirement of transmission system, several kind of voltage sag requires different voltage control strategies. Hence in this paper a flexible control strategy for three phase grid connected inverter is proposed. The inverter should be controlled in such way that it should inject reactive power in case of three phase balanced voltage sag condition in order to raise voltage in all three phases. In case of single line to ground fault, double line to ground fault condition and in several fault condition the main aim of inverter is to balance the voltages. The proposed inverter balances the voltages by sinking negative sequence components during this fault conditions. Thus the proposed control strategy avoids discontinuation of supply while accomplishing the chosen voltage support service so that voltage dips and voltage swell can be avoided. And this can be investigated and simulated by using Matlab/Simulink. This paper proposes a new control algorithm for the generation of the reference current which offers voltage provision in case of grid disturbances.