高频振荡抑制策略对柔性直流输电系统动态性能影响的综合评估

In recent years, high-frequency oscillation (HFO) issues in flexible HVDC transmission systems havehas been paid more and more attention, and several HFO suppression strategies have been proposed by related scholars. However, the impact of HFO suppression strategies on the dynamic performance of the flexible HVDC systems is not yet clear. The impacts of HFO suppression strategies on the dynamic performance of the flexible HVDC systems were comprehensively evaluated in terms of sub-/super-synchronous stability, dynamic response characteristics and fault ride- through characteristics,; and three typical HFO suppression strategies were analyzed comparatively. Firstly, the detailed wideband impedance models of modular multilevel convertor (MMC) under different HFO suppression strategies were established, respectively. The impacts of HFO suppression strategies on the risk of sub-/super-synchronous oscillations of the flexible HVDC system were analyzed by using the impedance- based analytical method. Then, the input-output and disturbance-output transfer functions were built, respectively, and the influences of HFO suppression strategies on the dynamic response characteristics of the flexible HVDC system were analyzed by theory and simulation results. Thirdly, a theoretical analysis model of the fault AC current peak value was established by considering the MMC current inner loop and the capacitor voltage dynamic, and the impacts of HFO suppression strategies on the fault transient characteristics of flexible HVDC systems were analyzed by theory and simulation. Finally, the influence of parameter interaction of HFO suppression strategy on the conclusion of single parameter analysis was discussed. The research results can provide references for the design of the HFO suppression strategiesy in practical flexible HVDC systems.