Research On Risk Comprehensive Assessment Of The Smart Distribution Grid

The study and construction of smart grid have been becoming the focus all over the word in recent years.With the rapid advance process of the smart grid,the net-work has been not only obtaining remarkable achievements,but also great challenges.The smart distribution grid faces more complex risk because that the grid connects to power users and supports actively the access of new energy power equipment,for example,distributed generation and electric vehicle.In order to ensure the normal op-eration of the smart distribution grid,it is necessary to grasp the risk type and severity of the network,so the risk condition of it should be evaluated constantly.Firstly,this paper selects the key risk factors,which affect the operation of the grid,based on analysis of characteristics for the grid.The multi-level evaluation sys-tem of the network that includes target layer,macro risk layer and micro index layer is established according to basic principles and general process of assessment.The risk severity of the network is divided into 5 levels,which are described by risk value range,it is convenient to assess condition of the network intuitively.Secondly,this paper provides a method of optimal weight allocation to the mul-ti-level evaluation system.Considering that the weight that is determined by fuzzy analytic hierarchy process ignores the influence of expert's subjective consciousness,the experts factor is defined to ingrate to the process of weight allocation so as the subjective weight becomes more effective.In order to consider the sequence charac-teristics of the evaluation parameters fully,the entropy is used to improve the tradi-tional CRITIC method.The objective weight is determined by comprehension of pa-rameters for all indicators in the historical stage,the current stage and the future stage.The traditional static evaluation is converted into dynamic evaluation that could pro-vide more reliable theory basis to the risk assessment for the smart distribution grid.Thirdly,this paper introduces the calculation method of risk value for micro in-dicator specifically.Set valued statistics expert valuation method is adopted for quali-tative assessment indicators.Expert evaluating trust factor is produced to measure the credibility of evaluation results considering that the assessment process is affected by fuzziness,randomness and psychological fluctuation of experts.The ridge fuzzy membership function is built as the evaluation function,its superiority is verified by comparison of the traditional evaluation function.In the end,a 10KV smart distribution network is as the research object in this paper to introduce the calculating process of overall risk value for the network in de-tail.The assessment method proposed in this paper could monitor the risk severity and weak link of the network,and quantify the risk condition accurately.In a word,the method could provide important guidance to promote optimal development of the network comprehensively.