LIU Jiangshan, LI Fengting, YIN Chunya, et al. Transient Voltage Suppression Strategy for Hybrid Cascaded HVDC Systems Based on Enhancement of System Reactive Power Short-Circuit Ratio[J]. 2025, 53(11): 126-134.
LIU Jiangshan, LI Fengting, YIN Chunya, et al. Transient Voltage Suppression Strategy for Hybrid Cascaded HVDC Systems Based on Enhancement of System Reactive Power Short-Circuit Ratio[J]. 2025, 53(11): 126-134. DOI: 10.20204/j.sp.2025.11015.
Transient Voltage Suppression Strategy for Hybrid Cascaded HVDC Systems Based on Enhancement of System Reactive Power Short-Circuit Ratio
To address the issue of transient overvoltage on the converter bus in sending-end hybrid cascaded HVDC systems caused by DC faults, a mathematical model of the transient overvoltage is derived,revealing a negative correlation between the reactive power short-circuit ratio and the transient overvoltage. First, a method is proposed where synchronous condensers and modular multilevel converters (MMCs) collaboratively support the steady-state reactive power demand under normal operating conditions. With the constraint that the transient voltage does not exceed limits, the required short-circuit capacity provided by the synchronous condenser is quantified to enhance the system’s reactive power short-circuit ratio. Second, a suppression strategy for transient voltage rise on the converter bus is introduced: during steady state, the reactive power compensation at the converter station is appropriately reduced based on the reactive power support capability of the MMC and synchronous condenser; after a DC fault, the line-commutated converter (LCC), MMC, and synchronous condenser jointly absorb the surplus reactive power in the system to suppress transient overvoltage. Finally, a simulation model of the sending-end hybrid cascaded HVDC system is built, validating the effectiveness of the proposed strategy in mitigating transient overvoltages caused by DC blockings and commutation failures.
YIN C Y,LI F T.Analytical expression on transient overvoltage peak value of converter bus caused by DC faults[J].IEEE Transactions on Power Systems,2021,36(3):2741-2744.
WANG T,PEI L,WANG J M,et al.Overvoltage suppression under commutation failure based on improved voltage-dependent current order limiter control strategy[J].IEEE Transactions on Industry Applications,2022,58(4):4914-4922.