| In recent years, the research and engineering application of substation technology is developing toward intelligent substation. The intelligent substations that based on IEC61850 standard and network technology have the functions of power transformation, power collection, power distribution and control, etc. Intelligent substation technology is an important part in smart grid, and its safety performance is directly related to the overall performance of the power system. The relay protection and safety control system is directly related to the ability of ensure system operating stably when power system have fault.For a long time, the continuously emerging of power system accidents caused by the hidden failures of relay protection system which is one of the main factors of power grid blackout accidents. Study the theory and method of relay protection hidden fault diagnosis is the main technical strategy to solve this problem, which realize the online diagnosis of hidden faults and condition monitoring for the relay protection device. Many international and domestic academics have carry on research on the hidden fault diagnosis of relay protection for years, however, due to the diagnostic information insufficiency, and information synchronization and transmission difficultly in traditional relay protection system, there is little available achievement about hidden fault diagnosis and engineering application.The architecture of intelligent substation is beneficial to realize the information extraction and sharing in protection system and it provided the environment to adopt new hidden fault diagnosis technology. In this paper, the research object is the hidden fault diagnosis of the relay protection system based on the intelligent substation, and it tries to propose a new relay protection hidden fault diagnosis theory and methods to provide new technical strategy for the safety of the relay protection system and the grid.This thesis summarized the domestic and foreign standard theory and technology method of grid fault diagnosis and relay protection security, then it evaluated each method and points out the limitation and applicability.Based on the architecture of intelligent substation, this thesis compared the difference between traditional substation and intelligent substation, and analyzed the new features of relay protection in intelligent substation. Based on the information structure of intelligent substation, this thesis proposed an intelligent substation fault diagnosis system structure based on the data of SV network, GOOSE network and MMS network. Furthermore, it illuminates the fault diagnosis data flow of relay protection sensor link, protection device and command export link. This thesis analyzed required data pretreatment technology in hidden fault diagnosis of relay protection and the data preprocessing method is presented.The operating experience shows that probability of hidden failure is different in different sections of relay protection system, and different types of hidden faults result in different consequences. This thesis analyzed the hidden mode of each section of intelligent substation relay protection, the hidden fault diagnosis methods of current measurement circuit were studied. Then, this thesis proposed the concept of generalized ratio in measurement circuit, and established the state matrix of generalized ratio based on the constraints of substation bus current. Based on the measurement of secondary circuit current and solving the generalized ratio state matrix, it realized the reliability judgment on the protection current measurement of each interval circuit and monitor hidden failures in the hardware and software of the protection current measurement circuit. Electronic transformer of relay protection is also an important part to determine whether protection equipment works correctly. This thesis prorosed a fault diagnosis method of electronic transformer for its significance in relay protection system. In the end, it gives an example to verify the effectiveness of the proposed method.The dynamic behavior of relay protection during grid fault has a key influence on the correct action of relay protection. However, in the existing research, it is difficult to scientifically judge the protective behavior due to the difficult to obtain the dynamic data in relay protection. In addition, a number of substation protections starting caused by the disturbance of power system and a large number of generated information cannot be used to the relay protection hidden failure analysis. Aim to solve this problem, this thesis proposed the idea of relay protection synchronous state analysis by making full use of wide area data generated by substation relay protection in different regions under the excitation of the disturbance, which is convenience to check the sensitivity, reliability and whether there have hidden failures in the cooperation of each protection under the same excitation. In order to realize this idea, the simplify problem of big data should be solved and the appropriate index system should be constructed. Based on the division of relay protection state region, this thesis constructs the index model of the fault starting, fault measurement and fault response time, and it proposed new methods for hidden fault diagnosis and operation status evaluation of multiple relay protections based on the reliability, selectivity, sensitivity and rapidity. The method can directly reflect the dynamic process of relay protection system and the accuracy of measured value and set value between single protection and multiple protections. Furthermore, this method provides a new strategy to improve the reliability of wide area protection.The architecture of intelligent substation contributes to the logic opening-up and hardware standardization in relay protection. This thesis proposed the concept that realizes the online implementation of relay protection system using the hardware redundancy of protection system during the relay protection device has fault. Also, this thesis analyses the potential demand of relay protection system reconstruction in power system, then, it proposed the universal model and four principles of relay protection system reconstruction. Based on these principles, this thesis take the failure of wide area protection communication system as an example, discusses the mathematical model and the solving process of wide area communication network failure reconstruction based on the proposed reliability criterion, and the result proved the feasibility of the protection system reconstruction. The proposed reconstruction thought can also be used to the optimize sensor placement and design of the existing protection. This thesis also introduces the invention of using reconstruct transformer current differential protection sensors to improve the protection performance.The construction of intelligent substation and smart grid can not only offer more available information for the relay protection system, but also provides a new opportunity to solve the security problem of relay protection system. This paper proposes the information architecture of hidden fault diagnosis of relay protection which is suitable for the intelligent substation architecture, and show a new way of hidden fault diagnosis by breaking the key link of hidden fault diagnosis. At the same time, in order to make full use of grid disturbance excitation in the era of big data, a solution method for the construction of the wide area diagnosis system of relay protection is presented. In addition, this paper proposes a new concept of relay protection reconstruction and the case of reconstruction, to realize isolate fault device after the discovery of hidden fault and recover protection system function. |
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