Reliability And Risk Analysis Of Secondary System In Smart Substation

Smart substation is the development trend of substation technology in the future.As a very important role in the construction of smart grid,it is reliable,safe,economical and environmentally friendly,and has attracted extensive attention from experts and scholars around the world.The smart substation are very different from the traditional substation in component composition and system structure of the secondary system,what's more,the operational risk of the secondary system directly affects the safe and stable of the substation or even the power grid.The research on the safety analysis of the secondary system of intelligent substation has a good theoretical significance and practical guiding significance.Under the background,this paper analyzes the two aspects of the secondary system of intelligent substation,which are reliability and risk.In terms of reliability,firstly,for the problem of secondary equipment status evaluation,this paper proposes the secondary equipment status assessment model and the status evaluation result confidence evaluation method.Then,for the reliability analysis of the secondary equipment,the reliability of the secondary equipment is analyzed from the two data conditions of large sample data and small sample data.Further,for the reliability problem of the secondary system,a secondary system availability analysis method considering the multi-state condition of the component is proposed.In terms of risk analysis,this paper proposes a secondary system risk assessment method based on functional relevance considering the risk transfer.Finally,secondary system security analysis is saw as an application scenario of power big data,the feasibility of secondary system security big data in equipment security diagnosis is discussed.The specific instructions are as follows:(1)This paper proposes a generalized model for state evaluation of secondary equipment based on multi-dimensional state information.Firstly,the state information of the secondary equipment of intelligent substation is combed from multiple dimensions,and the state evaluation model of secondary equipment based on the importance of state information is established.The model can solve the problem that the quantity of state information in the traditional evaluation model affects the evaluation result,and is applicable to all secondary devices.In addition,for the influence of the difference in the monitoring capability of the secondary equipment in the intelligent substation on the evaluation results,the credibility is introduced to distinguish the state evaluation results of the secondary equipment.By establishing a state information standard library,the credibility of the state evaluation results of the secondary equipment is evaluated from three aspects: state information integrity,real-time and accuracy.Finally,an example is given to illustrate the superiority of the model.(2)This paper presents a reliability evaluation and prediction model based on the electrical equipment performance data of small sample.Firstly,an improved Bootstrap method is used to expand the performance data of small sample,in order to analyze the distribution function of the performance.On the basis of this,the definition of equipment performance reliability is proposed to calculate the reliability in instantaneous time.Then the reliability curves are fitted based on morphological similarity distance.Finally,the reliability of the equipment is estimated based on the predicted value and the prediction error.The example results show the effectiveness and practicability of the proposed method based on small sample data.(3)This paper proposes a new reliability analysis model for secondary system in multi-state mode.Unlike conventional binary-state reliability methods,the proposed method takes into account the various states of components,which can more accurately compute the probabilities of SASs in any states,and further meet SAS Delicacy Management,such as wiring type selection,maintenance time decision and so on.In this paper,SAS is viewed as a network consisting of functional related automation devices(AD),which can be described by The Structural Functions and The Correlation Matrixes.We assess the dynamic element state probabilities of each aging multi-state automation device using a stochastic process model which is identified as a Markov model.The state distribution of the entire SAS is evaluated via the combination of the stochastic process and universal generating function(UGF).Finally,it takes four typical SAS as an example to describe the validity and superiority of the multi-state model in the reliability evaluation.This paper also proposes an importance analysis model of multi-state system components to analyze the importance degree of ADs in SAS.(4)This paper proposes a new methodology for the risk assessment of SAS based on the functional relevance.The overall risk assessment is decomposed into three parts.The first one is the functional decomposition model for SAS by establishing a risk network,includes the basic concepts definition,functional association matrix construction,function library partition.The second one is focused on dissecting propagation mechanism among basic elements for SAS risk network.The last one is risk assessment according to a set of new risk indexes including three levels of SAS,which are device,function and system.Finally,an instance SAS of an intelligent substation is modeling to test the validity of proposed model.The result supports the usefulness of the risk assessment.