Issues in the grid frequency regulation with increased penetration of wind energy systems

This paper presents some of the issues being encountered in the system frequency regulation function when the penetration level of wind energy in the electric grid increases considerably. Enhanced share of wind energy in the system mix will result in a proportional reduction of the conventional generating capacity. The traditional synchronous generators, which form the backbone of large power system, possess certain qualities which are very essential in controlling the grid frequency. Inertia and speed droop are two such important parameters responsible for balancing the system frequency. Since the modern wind turbine generators (WTGs) operate in variable speed mode to extract optimum energy from the wind, the electrical coupling between these generators and the grid will be missing due to the power electronics interfacing. Thus the increasing penetration of wind energy in the existing system will reduce the total inertia and increase the overall system droop, which in turn result in increased frequency deviations after load events in the system.