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-change reactive power compensators (RPCs) can cause transient voltage disturbance at the weak sending end AC grid. To mitigate the voltage disturbance, this paper proposes a coordinated feedback power control method for the hybrid multi-infeed HVDC (HMI-HVDC) system consisting of an LCC-HVDC and a voltage source converter HVDC (VSC-HVDC) system. 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 station of VSC-HVDC, the rectifier and the inverter station of LCC-HVDC. Simulations results verify that the proposed strategy can effectively suppress the voltage disturbance without relying on remote communication, thus enhancing the operation performance of the HMI-HVDC system.