Adaptive Frequency-Regualtion Strategy of a DFIG for Enhancing Frequency Support Capability

Short-term frequency support (STFS) strategy with droop control of variable-speed wind turbine generators could provide fast frequency response to improve the maximum rate of change of frequency (MROCOF) and maximum frequency deviation (MFD); however, the improvement capability of MFD is weakened because of the dynamics of the maximum power point tracking operation control loop. To address the dynamics, an improved STFR strategy based on power tracking operation is suggested. To address the difficulties for assigning the control coefficients of power tracking operation mode suitable for various conditions, the adaptive control coefficients of power tracking operation mode are determined based on the fuzzy control with the inputs of frequency deviation and ROCOF. Simulations with various disturbances are carried out to investigate the performance of the improved STFS strategy. Results verify that the suggested STFS strategy boosts the improvement capability in terms of MFD and MROCOF under various scenarios.