Improvements in primary frequency regulation of the grid-connected variable speed wind turbine

Primary frequency regulation capability of the wind turbine generators is an appealing topic in order to consider safe increasing of the wind power integration into power grids. This study introduces improvements in the primary frequency contribution of the grid-connected variable speed wind turbine generators, which operate under de-loaded conditions. A new dynamic droop control approach based on the fuzzy logic system is proposed. In this control approach, the droop setting is continuously adjusted in response to the de-loaded rotor speed, the frequency deviation, and the rate of change of frequency In addition, a new dynamic de-loading technique based on the Sugeno-Fuzzy inference system is proposed where the de-loading percentage of the wind turbine generator is decided continuously according to the frequency deviation. The effectiveness of the proposed dynamic de-loading and dynamic droop control approaches is verified through extensive comparative studies. The simulation results confirmed that the proposed control approaches have the ability to provide transient and steady-state power-sharing and improve effectively the frequency stabilisation of the power system within the stable and secure limits of the wind turbine.