混合型MMC非闭锁型直流短路故障穿越策略分析和比较

Analysis and comparison of non-blocking DC short circuit fault ride-through strategies for hybrid MMC

针对半桥/全桥子模块和半桥/单极性全桥子模块这2类混合型模块化多电平换流器(MMC)的非闭锁型直流短路故障穿越问题,首先提出了满足故障穿越要求的2类混合型MMC的最优子模块配比方案。其次基于恒定可控MMC总能量控制,提出了混合型MMC非闭锁型直流短路故障穿越控制策略,使混合型MMC在故障穿越期间具备无功补偿及子模块电容电压均衡的能力。最后从故障穿越效果及代价等方面,对这2类混合型MMC非闭锁型直流短路故障穿越策略开展了对比分析,为混合型MMC及非闭锁型直流短路故障穿越策略在柔性直流输电工程中的应用提供借鉴与参考。

For the problem that non-blocking DC short circuit fault ride-through strategies of two typical hybrid MMCs(Modular Multilevel Converters)whose hybrid submodules are composed of HBSM(Half-Bridge SubModule)and FBSM(Full-Bridge SubModule),HBSM and UFBSM(Unipolar Full-Bridge SubModule)respectively,the optimal submodule ratio scheme of two types of hybrid MMCs that meets the requirements of fault ride-through is proposed firstly.Then a non-blocking DC short circuit fault ride-through control strategy based on the fixed and controlled MMC total energy control is proposed to ensure that the hybrid MMCs own the abilities of reactive power compensation and submodule voltage balancing during the DC short circuit fault ride-through.Finally,the two non-blocking DC short circuit fault ride-through strategies of two types of hybrid MMCs are compared and analyzed in terms of the fault ride-through effects and costs,which provides valuable reference for the application of hybrid MMCs and the non-blocking DC short circuit fault ride-through strategies in flexible DC transmission.