Research On Reliability Of Substation Automation System Based On IEC61850

In order to achieve the connotation that the interoperability of IED (Intelligent Electronic Device) in substation automation system based on IEC61850standard, IEC61850standard defines the system information model which has nothing to do with the IED and decomposes the function of substation automation system into logical nodes which is the smallest functional module with communication capability, then defines the information exchange model between the logical nodes. These series of features of the1EC61850standard make the structure, communication networks of the system and the distribution patterns of function have the characteristic of flexibility and diversity, while the function model has its standardization. But, on the other side, the system has its uncertainty.Substation automation system based on IEC61850standard is still in the development stage, the reliability of system is the concern for manufacturer and user. Besides, the third part of the IEC61850standard IEC61850-3describes the related indicators of reliability and availability of substation automation system based on IEC61850standard. Analyzing the reliability of substation automation system, especially when system has different distribution patterns of function, communication network structure and redundant configuration, not only provides reference indicators for quantitative analysis of the level of reliability of system, but also is helpful to analyze the rationality of the distribution patterns of function, communication network structure and redundant configuration of system, so as to provide a reference for system design and optimization,it has important theoretical and practical significance.Analyzing the reliability of the system’s hardware structure whiph include communications network is used to assess the reliability of traditional substation automation system. The hardware structure of substation automation system based on IEC61850standard has the characteristic of flexibility and diversity which makes the model has poor generality when analyzing the reliability of structure of substation automation system based on IEC61850standard. Besides, the function of substation automation system based on IEC61850standard has the characteristics of standardization and free distribution which makes the failure mechanism of system hardware and structure can not completely reflect failure mechanism of system function, it means the accuracy of the model has some deficiencies. Therefore, from the features of substation automation system based on IEC61850standard, this paper proposes to analyze the reliability of system from the perspective of function and assesses the reliability of system by calculating the reliability and availability of system functions. The basic research ideas are:decomposing the system function into connection diagram of logical nodes based on IEC61850standard so as to study analytical methods of function reliability and the IED importance, next, researching the influence of distribution patterns of function, communication network structure and redundant configuration on system reliability. At last, combining with system reliability model and characteristics of SCL file structure to research the design methods of reliability assessment tool based on SCL file for substation automation system.Firstly, the connotation of free distribution of function in substation automation system based on IEC61850standard is researched.Obtaining the connection diagram of logical nodes by decomposing the system function based on IEC61850standard is the first step in reliability analysis of system in this paper. Based on function decomposition model, the connotation of the free distribution of function and its influence on system reliability is researched qualitatively and proposed to assess rationality of the distribution patterns of function by comparing the function’s reliability with different distribution patterns.Secondly,based on function decomposition model, studying the reliability analytical method is one of the main contents in this article. In the field of reliability analysis, reliability and stable availability rate are used to measure the reliability of system from the transient and steady-state point of view. The theory of reliability block diagram is introduced to study the analytical method of function’s reliability based on reliability block diagram. Markov process theory is introduced to study the analytical method of function’s availability rate based on Markov process theory. Besides, GO method is introduced into the field of reliability analysis of substation automation system to study the analytical method of function’s reliability based on GO method. Besides, reliability block diagram, Markov process theory and GO method are suitable for analyzing the system reliability based on function’s principle.Thirdly, the IED importance can reflect the rationality of the distribution patterns of function and the structure of system to a certain extent, as well as hidden dangers and weaknesses of system. The Equipment Importance analysis is one of the important research contents in the field of reliability analysis. The analytical method of IED importance is researched relevantly. Based on characteristics that logic nodes attached to IED equipment, the analytical method of IED importance based on joint distribution of logic nodes is proposed, which means calculate the IED importance by analyzing all the logic nodes’ influence on system reliability.On the basis of the proposed analytical methods of system reliability and IED importance, the influence of distribution patterns of function, communication network structure and redundant configuration on system reliability is researched by using the indicators of function reliability and IED importance, so as to provide a reference for system design and optimization.Finally, from the practical point of view, the design and implementation of the reliability assessment tool is researched. Based on the system reliability model and characteristics that SCL file has the capacity to describe the system function and structure, design methods of reliability assessment tool for substation automation system based on SCL file is proposed, and the function and implementation of each module of the tool is introduced in great detail, which do some exploratory research in the field of reliability assessment tools for substation automation system.