Reliability test and evaluation study on MMC secondary board cards in flexible DC transmission system

DOI:	10.11809/bqzbgcxb2023.09.024
Keywords:	modular multilevel converter; flexible DC transmission; reliability test; reliability evaluation; accelerated factor
Abstract:	The secondary board cards of modular multilevel converter (MMC), which serves as a device to control, monitor and protect flexible DC converter valves, plays a key role in the flexible DC transmission system. An exploration is conducted on the reliability test and evaluation model of secondary MMC board cards around its reliable requirements in the transmission system. The characteristics of MMC secondary boards are analyzed to overcome the technical bottlenecks of traditional reliability test and evaluation methods, which require a large number of failure samples and a long test cycle;A weak link rapid excitation technique based on intensive test is proposed to excite the weak links of secondary boards, and the reliability accelerated test model and evaluation method are studied;An acceleration factor evaluation method based on stress analysis is proposed for MMC secondary board characteristics. Finally, a specific test scheme is designed by using this method to carry out reliability enhancement and accelerated tests on a set of secondary board cards. The test results show that this method is an effective way to stimulate the weak links of the board and find out its stress limit, thus evaluating its life expectancy. The reliable level of secondary MMC board cards can be greatly improved by this approach.
Published:	2023-09-28
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