Study on Wind-Turbine Generator System Sizing Considering Voltage Regulation and Overcurrent Relay Coordination

When the wind-turbine generator system (WTGS) is connected to a radial distribution system, it can improve reliability of system by achieving the appropriate voltage regulation via its suitable control action. In this case, protective relay coordination and voltage stability issues become important factors in determining the optimal size of the WTGS, and moreover in evaluating its maximum capacity. In this paper, the proposed algorithm for selecting the optimal size of WTGS is applied based on a power flow analysis by treating the WTGS as a regulated voltage source, which is added to the related utility substation. Also, it considers the coordination time interval (CTI) of existing relays to maintain their present settings, and therefore provides an efficient solution in power system restructuring process by connecting the WTGS with its optimal size. The case study is carried out to verify that the proposed method can effectively determine the optimal size of WTGS under tightly constrained conditions resulting from voltage regulation and required protective relay coordination problems.