Coordinated Feedback Power Control Method for Hybrid Multi-Infeed HVDC System

During the power modulation process of line commutated converter-based high-voltage direct current (LCC-HVDC), the transient power mismatch between the fast-change converter station and the slow-response reactive power compensators (RPCs) can cause transient voltage disturbances at the weak sending end of the AC grid. To mitigate such voltage disturbances, this paper proposes a coordinated feedback power control method for the hybrid multi-infeed HVDC (HMI-HVDC) system comprising an LCC-HVDC and voltage source converter-based HVDC (VSC-HVDC) systems. The mechanism of the disturbance caused by transient power mismatch is quantitatively analyzed, and the numerical relationship between the instantaneous unbalanced power and the AC voltage is derived. Based on the numerical relationship and considering the time-varying relationship of reactive power between converter stations, the unbalanced power is set as the feedback and coordinately distributed among the inverter stations of VSC-HVDC, and the rectifier and the inverter stations of LCC-HVDC. Simulation results verify that the proposed method can effectively suppress voltage disturbance without relying on remote communication, thus enhancing the operation performance of the HMI-HVDC system.