Improved utilization of grid connected voltage source converters in smart grid through local VAR compensation

In Smart Grid there are abundant number of grid connected Voltage Source Converters (VSC) in the form of Electric Vehicle (EV) battery chargers, Renewable Energy Source (RES) fed grid connected inverters etc., that can be used for active and reactive power support to the grid. The VSCs remain idle when the load in case of EV charger or the energy source in case of RES fed grid connected inverters is not available. This work presents a single-phase PQ theory based control strategy to improve the utilization factor of such converters by using them to support the reactive power to the local loads when they are idle. The proposed control scheme is implementable with less computational effort. The system is further analyzed by calculating appropriate minimum DC bus voltage for a given amount of reactive power to be supported. The analysis for the designed system is validated using MATLAB-Simulink based simulation and a scaled down laboratory based experimental setup. The results are in good agreement with the analysis.