考虑通信延时的远距离MMC-HVDC系统接入水电的电网惯量支撑

With the increasing integration scale of renewable energy, the receiving-end power grids are suffering from low inertia and weak support problems. It is desired that the large-capacity modular multilevel converter-based high-voltage direct current (MMC-HVDC) systems could provide inertia support for the receiving grids. However, current analysis mainly focuses on the inertia support of wind farms/photovoltaic plants integrated MMC-HVDC systems. This paper studied the inertia support of MMC-HVDC systems transmitting large-scale hydropower. Firstly, the inertia support capability of the MMC-HVDC system integrating hydropower is analyzed, considering the communication delay and the support strategies of different devices. Then, an inertia boost control scheme was proposed for the sending-end MMC, which maximizes the inertia support of the hydropower generator and MMC's capacitor energy. Furthermore, a method for assessing the inertia support performance of the MMC-HVDC system is proposed, which approximates the system's time-varying inertia as piecewise constants. Finally, simulations are performed in a two-terminal MMC-HVDC system to verify the effectiveness of the proposed analysis method and control strategy.