Reliability Analysis Of Hybrid Multilevel Converters

Voltage sourced converter based high voltage direct current(VSC-HVDC)shows widespread application prospect in DC transmission for its some unique advantages.In detail,it owns decouple between active power and reactive power and it does not have commutation failure.Flexible high voltage direct current developed quickly during the past years.And hybrid mult ilevel converters among that has captured many focus and research for their high efficiency and the capability of handling dc fault by converter itself.Reliability analysis is an important aspect for hybrid multilevel converter,which also is an important reference indice of optimal rendundancy configuration.In terms of above question,the reliability analysis of refered hybrid mult ilevel converters are constructed from two prospective which are classical probability and distribution function.Firstly,hybrid multilevel converter is limited to hybrid modular mult ilevel converter,arm alternate converter and hybrid cascaded multilevel converter followed by their respective topology.Furtherly,the init ial numbers of modules in above converters are calculated based on their topologies,operation princ iples in steady state and blocking principles in transient state.Then from classic probability's view,construct reliability analys is model given that the reliability of module keeps constant and independent.Based on this,analyze the corresponding relaibilty under different redundancy configuration in hybrid modular multilevel converter,arm alternate converter and hybrid cascaded multilevel converter.And optimal redundancy configuration is designed by combining reliability and utilization,which offers a theory and instructing significance to some extent.At last,pesuming reliability of each submodule is a function of time and is relevant.Take hybrid modular multilevel converter as example to establish the reliability model based on Copula theory and Copula function for analazing the infulence of different degree of correlation or redundancy configuration.