Working towards frequency regulation with wind plants: combined control approaches

A pitch angle controller and a rotor speed controller are proposed for wind plant output active power adjustment. Combining the turbine inertial control with pitch angle control provides a better outlook for long-term control. The control schemes are developed for wind generators to equip them with the capability to participate in restoring grid frequency after a disturbance. With the proposed controllers, the wind plant has a higher flexibility to operate more like a synchronous generator and is able to output either larger or smaller amounts of power as required so as to contribute to grid frequency restoration. The controllers are tested on a four-bus test system for verification of the grid frequency performance under varying system dynamic conditions.