Analysis of Single-Phase-to-Ground Faults at the Valve-Side of HB-MMCs in HVDC Systems

作者：Li, Gen; Liang, Jun; Ma, Fan; Ugalde-Loo, Carlos E.^*; Liang, Haifeng

来源：IEEE Transactions on Industrial Electronics, 2019, 66(3): 2444-2453.

DOI：10.1109/TIE.2018.2829666

• Fault tolerance
• ground faults
• half-bridge modular multilevel converter
• high-voltage direct-current systems
• station internal fault

Although the probability of occurrence of station internal ac grounding faults in modular multilevel converter (MMC)-based high-voltage direct-current systems is low, they may lead to severe consequences that should be considered when designing protection systems. This paper analyzes the characteristics of valve-side single-phase-to-ground (SPG) faults in three configurations of MMC systems. Fault responses for symmetrical monopole MMCs are first studied. Upper arm overvoltages and ac-side nonzero-crossing currents arising from SPG faults in asymmetrical and bipolar configurations are then investigated. DC grounding using an LR parallel circuit is employed to create current zero-crossings, which will enable the operation of grid-side ac circuit breakers. The theoretical analysis is verified through simulations performed in PSCAD/EMTDC, with simulation results and the theoretical analysis showing a good agreement. The studies in this paper will be valuable for the design of protection systems for station internal ac grounding faults.

• 出版日期2019-3
• 单位中国人民解放军海军工程大学; 华北电力大学（保定）; 华北电力大学