As wind power generation increases, there is an increasing need for frequency support from wind turbines. There are many advantages to connect offshore wind farms with the electricity grid via a high-voltage direct current (HVdc) system. HVdc transmission systems allow wind farms to provide frequency regulation and voltage control, making them more flexible compared with HVac transmission systems. Several frequency-support control methods have been developed previously. However, few works have compared various control methods for HVdc-connected offshore wind farms. This work presents a detailed comparison of the main frequency-support control methods that can be used for HVdc-connected offshore wind farms. These control approaches are mainly based on the communication-based schemes or coordination-based methods. The communication-based scheme uses communication devices to directly transfer the grid frequency information to an offshore wind farm. The coordination-based method transfers the dynamic dc voltage information from the HVdc via generator emulation control and then enables the voltage-source converter on the wind-farm side to supply frequency regulation. In this work, we considered the synthetic inertial control of wind turbines for our analysis, including inertia and droop controllers. Furthermore, the capacitors in the HVdc system can release the stored energy to help wind farms regulate frequency during operation.

中文翻译：

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高压直流海上风电场基于通信和基于协调的频率控制方案的比较


随着风力发电量的增加，对风力涡轮机频率支持的需求也越来越大。通过高压直流（HVdc）系统将海上风电场与电网连接有很多优点。高压直流输电系统允许风电场提供频率调节和电压控制，使其与高压交流输电系统相比更加灵活。先前已经开发了几种频率支持控制方法。然而，很少有文献比较高压直流海上风电场的各种控制方法。这项工作对可用于高压直流海上风电场的主要频率支持控制方法进行了详细比较。这些控制方法主要基于基于通信的方案或基于协调的方法。基于通信的方案利用通信设备将电网频率信息直接传输到海上风电场。基于协调的方法通过发电机仿真控制从HVdc传输动态直流电压信息，然后使风电场侧的电压源变流器提供频率调节。在这项工作中，我们考虑了风力涡轮机的综合惯性控制进行分析，包括惯性和下垂控制器。此外，高压直流系统中的电容器可以释放储存的能量，帮助风电场在运行过程中调节频率。