Frequency stability enhancement of AC microgrid with high share of wind energy

Due to technical, economic, and environmental benefits of microgrids, its applications have been become promising solutions. Electricity generation from wind energy has significant contribution in renewable energy applications inside microgrids. However, decupling between wind generator and microgrid, due to presence of grid interface converters (GIC) for integration and maximum power point (MPP) operation, reduces the microgrid inertia compared to traditional generation system. This inertia reduction has adverse effect on the frequency stability, nadir, and rate of change of frequency (ROCOF), when the microgrid is experienced to load or generation disturbances. A lot of efforts have been made through generators deloading techniques and/or using of energy storage systems (ESSs) to introduce synthetic inertia in the system. The aforementioned techniques have financial drawbacks. Utilizing the natural inertia of wind generation system to enhance the microgrid inertia still requires additional efforts. In this article, the inherent inertia of the wind generation system, the fast control capability of GIC, and advancement in control technique are employed to introduce inertia response into the microgrid, while the wind generation system works very near to the MPP. In addition, the applied control technique uses the frequency signal instead of the frequency derivative, which avoids deterioration of the system stability and averts noise amplifications. The controller is tuned to mimic the inertia performance of traditional generation. The mathematical derivation which necessary for the control objective is deduced and verified by simulation using MATLAB platform. The technique is applied on microgrid comprises of wind generation system, thermal generation unit and electrical load. The response of the microgrid with suggested control is justified with the performance of two other microgrids operate under the same disturbance.