基于全桥型MMC的开关序列切换方法及IGBT开路故障诊断策略  

A Switching Sequence Switching Method and IGBT Open Circuit Fault Diagnosis Strategy for Full-bridge MMC

作　　者：武鸿 王跃[1] 刘熠 李鹏坤 WU Hong;WANG Yue;LIU Yi;LI Pengkun(State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学电工材料电气绝缘全国重点实验室,西安710049

出　　处：《高电压技术》2024年第4期1608-1620,共13页High Voltage Engineering

基　　金：国家电网有限公司科技项目(5100-202256486A-2-0-KJ)。

摘　　要：全桥型模块化多电平换流器(modular multilevel converter,MMC)因具备直流故障穿越能力受到广泛关注,但全桥子模块(full-bridge submodule,FBSM)中更多的开关器件数量对MMC的运行可靠性带来了巨大挑战。针对于此,首先提出了基于全桥型MMC的开关序列(switching sequence,SS)切换方法,通过增加一种子模块(submodule,SM)切除状态,能在不额外增加开关损耗的基础上,使所有类型IGBT开路故障均能够体现故障特性。进一步,分析了所提SS切换方法下的故障特点,并提出了IGBT开路故障诊断策略。所提策略通过判断SS计数是否超出阈值对故障进行检测,并定位故障SM,之后基于SS计数的正负或电容电压变化值进一步辨别故障类型。所提故障诊断策略能够准确检测出IGBT故障,定位出发生IGBT开路故障的SM,并辨别其故障类型,有利于主动运维。此外,所提策略无需额外硬件,并可在一个工频周期(20 ms)内完成对所有故障的准确诊断。最后通过硬件在环平台验证了所提SS切换方法及IGBT开路故障诊断策略的有效性。The full-bridge modular multilevel converter(MMC)has attracted extensive attention due to its DC fault ride through capability,however,the greater number of switching devices in the full-bridge submodule(FBSM)poses a huge challenge to the operational reliability of the MMC.To cope with this problem,this article first proposes a switching sequence(SS)method based on the full-bridge MMC by adding a switched-out state,all types of IGBT open-circuit faults can be reflected without additional switching loss.Further,this article analyzes the fault characteristic under the proposed SS switching method and propose a IGBT open-circuit fault diagnosis strategy.In the proposed fault diagnosis strategy,detects and faults are detected and all faulty SMs are located by judging whether the switching sequence count exceeds the threshold,and further the faulty type is distinguished through the polarity of the SS count and the change of the capacitor voltage.The proposed fault diagnosis strategy can accurately detect the IGBT open-circuit faults,locate the malfunctioning SMs and indentify the faulty type,which is beneficial to active operation and maintenance.In addition,the proposed strategy does not require additional hardware and can diagnose all the faults correctly within one power frequency period(20 ms).Finally,the effectiveness of the proposed SS switching method and IGBT open-circuit fault diagnosis strategy is verified by hardware-in-the-loop platform.

关 键 词：模块化多电平换流器 全桥子模块 开路故障诊断 开关序列 故障类型 开关损耗 

分 类 号：TM46[电气工程—电器] TN322.8[电子电信—物理电子学]