Frequency Coordinated Control of Wind Power Flexible Direct System Based on Voltage Sourced Converter Based Multi-Terminal High Voltage Direct Current

Abstract

Background: With the continuous penetration of renewable energy in modern power systems, the problem of excessive frequency deviation of power systems, which is caused by the integration of wind power into electricity grids, needs to be solved urgently. Objective: Make up for frequency fluctuations when AC systems fail, improve the frequency characteristics of main system networks, and reasonably distribute unbalanced power. Methods: According to the principle of active power distribution, a frequency division coordinated control strategy that uses low-pass filter control to divide power fluctuations into highfrequency fluctuations and low-frequency fluctuations is proposed. High-frequency fluctuations are attached to the wind farm side, and low-frequency fluctuations are attached to the DC system to realize frequency division control. Result: The simulation results showed that the coordination of the frequency division control of the wind farm and flexible DC system could effectively reduce the main grid’s frequency fluctuations, which are caused by the AC system failure, and improve the stable operation ability of the AC and DC systems. Conclusion: The frequency division control can overcome the unbalanced power distribution caused by traditional droop control, reduce the frequency deviation of the AC system, realize frequency autonomy, and enhance system robustness.