Modified current control technique for grid synchronization in voltage source converters

Design of a stable microgrid tied to the ac power grid requires an efficient, coordinated and controlled system operation. Energy management, power exchange, stability, reliability and protection are the key factors that necessitates extensive research on micro grids and their interconnection. This paper reviews the conventional method of controlling the output current injected by the grid connected voltage source converters to the ac power system. Modified synchronous reference frame control strategy is implemented using discrete PI controllers. The drawback of conventional SRF scheme is overcome in the new method. A detailed discussion of both analytical and simulation results obtained for linear inductive loads is included in this paper. Selection of the appropriate control strategy depends on the required system stability and power quality. The future scope for separate control on both active and reactive power is also investigated through analytical observations. Simulation results obtained validate the test system in case of linear balanced loads.