The involvement of wind turbines operating at load shedding levels in primary frequency regulation serves as a crucial technical solution to provide high levels of inertial response capability and frequency regulation capability in power systems with significant proportions of renewable energy. Load-shedding units' frequency regulation capacity is constrained by the optimal operating speed, which prevents the utilization of the rotor's full kinetic energy and consequently limits the system's ability to provide strong inertia support. Additionally, the units are restricted by the maximum speed in the medium wind speed range, resulting in a reduced reserve capacity. The control mechanism of virtual synchronous generator (VSG) can ensure voltage stability at the machine end, and enable real-time tracking of the grid frequency, thereby imparting to wind turbines the on-grid operation characteristics of synchronous generator sets. To achieve this goal, this paper proposes a coordinated frequency control method for variable-speed variable-pitch doubly fed induction generator units based on VSG. Differentiated control strategies are employed for varying wind speed ranges, while an additional frequency control module is utilized to realize frequency regulation functionality. In conjunction with VSG, this approach enhances the inertial response of the units and strengthens their ability to support grid frequency. Simulation results indicate that the proposed control method mitigates the rate of decline in grid frequency and reduces frequency deviation, ultimately promoting grid stability. Additionally, a simulation system was designed based on the conventional four-machine two-area model to verify the effectiveness of this approach.

中文翻译：

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基于VSG的DFIG减载机组变速变桨协调频率控制研究

甩负荷运行的风电机组参与一次调频是在可再生能源占比较高的电力系统中提供高水平惯性响应能力和调频能力的关键技术解决方案。减负荷机组的调频能力受到最佳运行转速的限制，无法充分利用转子的动能，从而限制了系统提供强大惯性支撑的能力。另外，机组在中风速范围内受到最大风速的限制，导致储备容量减少。虚拟同步发电机（VSG）的控制机制可以保证机端电压稳定，并能实时跟踪电网频率，从而赋予风电机组同步发电机组的并网运行特性。为了实现这一目标，本文提出一种基于VSG的变速变桨双馈感应发电机组协调频率控制方法。针对不同的风速范围采用差异化的控制策略，同时利用附加的频率控制模块来实现频率调节功能。与 VSG 结合，这种方法增强了机组的惯性响应，并增强了它们支持电网频率的能力。仿真结果表明，所提出的控制方法减缓了电网频率的下降速度，减少了频率偏差，最终促进了电网的稳定性。此外，基于传统的四机两区模型设计了仿真系统来验证该方法的有效性。