A New Coordinated Control Strategy to Improve the Frequency Stability of Microgrid Based on De-Loaded Capacity of Wind Turbine

The wind turbine’s low inertia and the insufficient frequency response ability may result in the frequency instability when the microgrid operates in isolated operation. In view of this, this paper proposes a frequency control method considering the wind turbine de-loaded capacity, which refers to the rotating reserve capacity when the wind turbine is running at a non-MPPT point. The wind turbine immediately releases the rotating reserve kinetic energy, which not only provides inertial support, but also provides a certain power shortage when the frequency is disturbed. Meanwhile, in order to calculate the demand of the de-loaded capacity, a fuzzy droop controller is designed whose parameters are optimized according to the ABC (artificial bee colony) algorithm. Finally, the experimental results verifed that this method can dramatically increase the system stability, comparing with other traditional PID control strategy.