Research On The Comprehensive Evaluation Method Of DC Distribution Network Voltage Level Based On Weighted Multiple Indicators

In order to realize the application of DC technology at an early date and reasonably select the voltage level of DC distribution network,this article relies on the Shanxi Province Science and Technology Major Project "Key Technology of Low and Medium Voltage AC/DC Distribution Network"(20181102028)and focuses on the setting law and constraints of voltage level,extraction of factors affecting the setting of voltage level,hierarchical analysis of influencing factors,research and calculation of relevant influencing factors and indexes,proposal of comprehensive evaluation of voltage level with cases,establishment of characteristic DC scenarios and evaluation of voltage selection,etc.The main work is as follows.The article analyzes the principles inherent in the two principles of voltage selection and supports them with case studies.The constraints of DC voltage selection are studied in terms of future load demand,current development of DC equipment technology,and DC distribution network power supply mode and structure.On the basis of following the above principles and constraints,the DC distribution network voltage selection problem is converted into a two-level comprehensive evaluation system,in which the indicators in the first level are economy,reliability and adaptability,and the second level is divided into factors such as construction cost,operation cost,converter station reliability,DC breaker reliability and DC transformer reliability.A relevant power supply model is established for the calculation of economy and the construction cost and operation cost under the annual equivalent of medium voltage scenario are calculated.The physical models of DC converter station,DC breaker,and DC transformer are studied separately for reliability calculation,and the related reliability parameters are obtained;the conversion relationship between variable language and numerical values in Vague concentration is used to determine the data for the unquantifiable indexes.Then,a comprehensive evaluation method of DC voltage level based on weighted multiple indicators is proposed,and the weight size of the indicators is analyzed according to the characteristics of different scenarios using the advantages of hierarchical analysis,and the calculated indicator data are dimensionless and isotropic processed.The obtained weights are assigned to the processed data to get the weighted judgment matrix,and the relative distance between each scenario and the ideal solution in Euclidean space is derived using the ideal solution distance method,and the optimal voltage scenario under the modified evaluation system is obtained according to the magnitude of the relative distance.Finally,the residential light storage and charging scenario is analyzed and established from the power generation side,energy storage,access demand,and distribution network composition;the current situation of coal mine power distribution development and equipment load are analyzed to get the feasibility results of coal mine scenario establishment,and the DC power distribution scenario scheme under the coal mine is given.Finally,the preliminary voltages of the two scenarios are evaluated by a comprehensive evaluation method of DC voltage levels based on weighted multi-indicators and the comprehensive optimal voltage scheme is finally obtained.