CAJ | 학술논문

模块化多电平换流器(MMC)桥臂中冗余子模块的存在是换流器可靠运行的重要保障，能够避免子模块故障时换流器无法正常运行甚至可能退出运行的风险。为此，分析了不同调制策略下冗余保护的换流器损耗，并基于此提出了基于载波移相调制的新型冗余保护策略。该策略在故障后根据子模块的运行状态进行载波动态分配，无需记录载波量；可通过改变载波来切换冗余子模块和未故障子模块的运行状态，优先为冗余子模块充电；同时，引入电容电压优化控制，以保证附加载波控制时桥臂的电容电压波动较小，降低相间环流和维持控制器的稳定。7电平和101电平 MMC系统的仿真结果验证了所提冗余保护策略的有效性和通用性，且对系统控制稳定性影响较小。
모괴화다전평환류기(MMC)교비중용여자모괴적존재시환류기가고운행적중요보장，능구피면자모괴고장시환류기무법정상운행심지가능퇴출운행적풍험。위차，분석료불동조제책략하용여보호적환류기손모，병기우차제출료기우재파이상조제적신형용여보호책략。해책략재고장후근거자모괴적운행상태진행재파동태분배，무수기록재파량；가통과개변재파래절환용여자모괴화미고장자모괴적운행상태，우선위용여자모괴충전；동시，인입전용전압우화공제，이보증부가재파공제시교비적전용전압파동교소，강저상간배류화유지공제기적은정。7전평화101전평 MMC계통적방진결과험증료소제용여보호책략적유효성화통용성，차대계통공제은정성영향교소。
The existence of redundant sub-modules (SMs) is an important guarantee of reliability of modular multilevel converters (MMCs) to avoid the risk of abnormal operation and even outage.A novel redundant protection strategy based on carrier phase-shifted sinusoidal pulse width modulation(CPS-SPWM) is proposed,which includes carrier dynamic allocation, additional carrier control and optimization of capacitor voltage.The carrier dynamic allocation rearranges the carriers of SMs without additional records.The additional carrier control adjusts the state of the redundant SMs to retain their priority to be charged.The optimization of capacitor voltage is capable of maintaining slight fluctuation of the capacitor voltage as well as reducing the circulating current.Simulation results of a 7-level and a 101-level MMC system by PSCAD/EMTDC show that the proposed strategy is effective and generic for various voltage-level MMC systems to ensure successful converter operation when a SM fault occurs.