Research On Reliability Model Of Key Equipment In DC Distribution Center

With the steady progress of the new energy strategy,the access of a large number of distributed energy sources has brought huge challenges to the traditional distribution network.At the same time,the development of DC transmission and distribution technology and power electronics technology has enabled plot energy to be connected to the grid in a more flexible way.This paper relies on the key equipment and technology research demonstration project for flexible interconnection of urban power distribution network of Guizhou University,and focuses on the hybrid MMC converter and ISOP DC transformer of the new type of DC power distribution center that can only be equipped with key equipment,and develops device level and sub-module And equipment-level reliability model research work.The specific research content is as follows:For the research of device-level reliability model,this article starts from the topology and failure mechanism of IGBT module,establishes its electro-thermal coupling model for welded IGBT,calculates its instantaneous junction temperature based on the real-time data of the demonstration project,and then uses rain flow algorithm to extract the junction.The temperature cycle information is used to predict the life of the IGBT module according to the Bayerer life model to obtain its reliability parameters.Aiming at the research of sub-module reliability model,this paper introduces three sub-modules applied to the key equipment of DC power distribution center,and elaborates its topology and working principle in detail.Firstly,based on the topological structure of the three different types of sub-modules,the reliability model is established without considering the correlation,and then the Gumbel-type Copula function is used to establish the reliability joint probability distribution function for the series structure of the sub-modules of the same structure and different structures.Decoupling gets the sub-module reliability model that can consider the correlation.Taking the key equipment of DC power distribution center as an example,the reliability model of the series structure of MMC bridge arm and DAB sub-module is studied,and the influence of topology structure,redundancy and correlation coefficient on reliability is analyzed.Aiming at the equipment-level reliability model research,this paper adopts the component counting method and fault tree analysis based on the correlation of submodules,and performs reliability based on the topology and redundancy design of the hybrid MMC converter of the DC distribution center and the ISOP DC transformer Model research and reliability analysis.This paper studies the reliability model of key DC power distribution equipment at the device level,sub-module and equipment level,and obtains the life prediction and reliability parameters of the IGBT module,the decoupling reliability model of the submodule and the equipment reliability parameter respectively.Complete the study of reliability models at the device level,sub-module and equipment level,which can provide references for equipment design and system reliability evaluation...