Analysis and Mitigation of Undesirable Impacts of Implementing Frequency Support Controllers in Wind Power Generation

Abstract

Wind power generation is increasing, rapidly forming a significant part of the power systems of the near future. Thus, incorporating wind power into frequency regulation seems necessary. Droop and virtual inertia are two key methods for involving the wind power in frequency regulation. However, when these methods are applied, undesirable effects can be induced. However, the mitigation of such impacts has not yet been analyzed. The rate of change of power (ROCOP) of a wind generator could be a major factor limiting the effective implementation of frequency regulation methods. Whereas high ROCOP leads to wear and tear and increases the maintenance cost, simply limiting the ROCOP of the generator by a ramp-limit control function will neutralize the desired impact of frequency regulation. In this paper, small-signal analysis is employed to study the impact of frequency regulation methods on the ROCOP of wind turbines considering the two-mass mechanical dynamics. Both doubly fed induction generator- and permanent-magnet synchronous generator-based turbines are considered. An effective solution, based on utilizing the converter dc-link capacitor, is proposed, analyzed, and compared to the conventional ramp-rate limit method in different aspects. Time-domain simulation is used to validate the analytical results.