基于匹配控制的海上风电柔直送出系统联动调频控制策略

Interconnection Frequency Regulation Control Strategy for Offshore Wind Farm and Flexible Direct Transmission System Based on Matching Control

  • 摘要: 大规模海上风电柔性直流送出系统(voltage source converter based high voltage direct current,VSC-HVDC)可以通过双端换流站的联动作用调节风电机组功率,提升陆上电网的调频能力。为解决远海风电场输出功率与陆上电网频率耦合性差和响应滞后的问题,该文提出一种基于匹配控制的陆海换流站协同调频方法。该策略采用双端对称的匹配控制结构,将陆上电网的频率变化通过VSC-HVDC直流电压耦合传递至海上风电侧,并在风电变流器中结合虚拟同步机技术与自适应变阻尼减载控制,使得各风电机组无需通信即可快速响应陆上电网频率波动,动态提供频率支撑功率。通过MATLAB/Simulink软件建立大容量等值直驱型风电机组经VSC-HVDC并网的仿真模型,在弱电网条件下仿真验证了基于匹配控制的VSC-HVDC与海上风电系统联动调频策略的有效性。

    Abstract: The frequency regulation capability of the onshore power grid can be enhanced by utilizing the linkage effect of two-terminal converter stations in large-scale offshore wind power output of wind turbines. To address the issues of poor coupling and the delayed response between the output power of the far-offshore wind farms and the frequency of the onshore grid, in this paper we propose a grid-forming matching control and strategy for coordinated frequency regulation of converter stations at both sea-land ends. The process of the frequency change of the onshore grid is restored to the offshore wind farm through the coupling of VSC-HVDC DC voltage by symmetric matching control. Furthermore, the wind converter is combined with the virtual synchronous machine based variable damping coefficient load shedding control method, enabling each offshore wind turbine to promptly respond to the frequency fluctuation of the onshore grid without communication and provide the corresponding standby power. A simulation model of large-capacity equivalent direct-drive WTGs connected to the grid via VSC-HVDC is established in MATLAB/Simulink software. The effectiveness of the interconnection frequency regulation strategy between VSC-HVDC and offshore wind power system based on matching control is verified through simulation under weak grid conditions.

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