Since the operation of the first flexible HVDC transmission line in 1997 in Hellsjon

Sweden and throughout many-year development

dozens of flexible HVDC transmission lines have been constructed and put into operation both at home and abroad. However

the flexible HVDC transmission lines with modular multilevel structure just started construction and operation around 2010. The overall operation time is relatively short and the the operation parameters of each equipment are still in accumulation stage. For the DC-link capacitor used in MMC power modules

further study for such detailed parameters as specific operating conditions and application conditions is still needed. Therefore

the test conditions and methods for this type of capacitor remain to be studied. From the perspective of practical application

the purpose of the stray inductance measurement test is analyzed and the relevant test methods are discussed

which can provide some reference for laboratory implementation.