Reliability Modeling And Fast Evaluation Method Of Active Distribution System Considering Cyber Invalidity

In recent years,with the increasingly serious social problems such as environmental pollution and energy depletion,renewable distributed energy resources(DERs)participate in the operation of distribution network on a large scale.On the one hand,active control can optimize the operation state of distribution network and solve the problems of DER intermittence,uncertainty and volatility;On the other hand,it can realize fault recovery and improve the economy and reliability of distribution network operation.However,active control is inseparable from information and communication technology.Cyber system failure has become one of the main factors affecting the reliable operation of distribution network.Therefore,it is necessary to evaluate the reliability of distribution network considering the influence of information failure.Based on the background,this paper carries out the following research:Firstly,based on the whole process of distribution network fault processing,this paper analyzes the typical structure of active distribution system(ADS),and studies the influence of cyebr failure on fault location,isolation and service restoration(FLISR).Secondly,the paper establishes the validity model of the switch of cyber link and cyber coupling,which lays the foundation for the application of analytical method.Including:(1)In the cyber system modeling,the influence of equipment failure,transmission delay and channel error is considered,and then a refined cyber link validity model is established;(2)A fast solution method of cyber link validity based on frequency time domain conversion is proposed,which effectively reduces a lot of convolution calculation in analytical solution and improves the computational efficiency;(3)Based on the influence of cyber link failure on the FLISR process,combined with the switch’s own failure probability,a switch validity model considering the influence of monitoring,control and control feedback information is established.Thirdly,This paper presents a rapid evaluation method of ADS reliability.Including:(1)Based on the switch validity model and line validity model under the influence of cyber system fault,the switch up equivalent method is proposed to correct the equivalent mean outage time in the downstream area of the fault;(2)Considering the probability of load transfer,the reliability calculation model of three types of users in common,tie line and planned island is established.Thus,the reliability analysis calculation method of distribution network considering the influence of information system fault is proposed.Finally,based on the improved F4 feeder in IEEE RBTS BUS 6 system,(1)The accuracy and efficiency of the algorithm are verified;(2)Considering fault recovery,the contribution of tie line transfer and planned island operation to distribution network reliability under the influence of cyber failure is verified;(3)This paper analyzes the influence of the matching between the physical element dependence and the cyber link validity on the reliability of ADS,and puts forward the improved connection method between the cyber link and the physical element,which has guiding significance for the actual construction of ADS.