Abstract With the increasing penetration level of renewable power, the power systems’ inertias are decreasing. To ensure that the frequency is above the threshold of the under frequency load shedding, one effective way is to share the spinning reserves among asynchronous AC grids through HVDC systems. In this paper, a coordinated frequency regulation scheme that enables spinning reserves sharing is proposed for such hybrid AC/DC grids. This scheme is a communication-free method that consists of the droop control, the inertia emulation control and the frequency safety control. The combined response of the three controls can increase not only the frequency nadir but also the settled frequency of the disturbed grid. In addition, the hysteresis comparators and the power injection limits are adopted in the frequency regulation scheme to reduce the coupling effect among AC grids. Thus, under small and harmless disturbance, the frequency regulation scheme will be inactive; the disturbance in strong AC grids would not affect the weak AC systems. The frequency regulation scheme coordinates well with the automatic generation control of the grids. The feasibility and effectiveness of the proposed frequency regulation scheme are verified through simulation studies.

中文翻译：

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具有 MTDC 系统的异步交流电网之间的协调频率调节

摘要 随着可再生能源普及率的不断提高，电力系统的惯性越来越小。为了确保频率高于低频减载阈值，一种有效的方法是通过 HVDC 系统在异步交流电网之间共享旋转储备。在本文中，针对这种混合 AC/DC 电网，提出了一种能够实现旋转备用共享的协调频率调节方案。该方案是一种由下垂控制、惯性仿真控制和频率安全控制组成的免通信方式。三个控制的组合响应不仅可以增加频率最低点，还可以增加被扰动电网的稳定频率。此外，调频方案采用滞后比较器和功率注入限制，以减少交流电网之间的耦合效应。因此，在小而无害的干扰下，调频方案将无效；强交流电网的干扰不会影响弱交流系统。频率调节方案与电网的自动发电控制很好地协调。通过仿真研究验证了所提出的频率调节方案的可行性和有效性。