A System-View Optimal Additional Active Power Control of Wind Turbines for Grid Frequency Support

TL;DR

This paper introduces an optimal active power control method for wind turbines to enhance grid frequency stability, outperforming traditional virtual inertia control by maximizing the frequency nadir after major disturbances.

Contribution

It develops a universal optimal control strategy based on frequency trajectory modeling, enabling real-time deployment without heavy computational load.

Findings

Significantly improves system frequency nadir in simulations.

Proves the universality of the optimal frequency trajectory.

Demonstrates effectiveness in two-machine and IEEE 39 bus systems.

Abstract

Additional active power control (AAPC) of wind turbines (WTs) is essential to improve the transient frequency stability of low-inertia power systems. Most of the existing research has focused on imitating the frequency response of the synchronous generator (SG), known as virtual inertia control (VIC), but are such control laws optimal for the power systems? Inspired by this question, this paper proposes an optimal AAPC of WTs to maximize the frequency nadir post a major power deficit. By decoupling the WT response and the frequency dynamics, the optimal frequency trajectory is solved based on the trajectory model, and its universality is strictly proven. Then the optimal AAPC of WTs is constructed reversely based on the average system frequency (ASF) model with the optimal frequency trajectory as the desired control results. The proposed method can significantly improve the system frequency nadir. Meanwhile, the event insensitivity makes it can be deployed based on the on-line rolling update under a hypothetic disturbance, avoiding the heavy post-event computational burden. Finally, simulation results in a two-machine power system and the IEEE 39 bus power system verify the effectiveness of the optimal AAPC of WTs.