Research Of Power Grid Intelligent Decision System Based On Relay Protection And Fault Information System

In recent years, following the high speed growth of national economy and the social fast advancement, the electric power has been developed quickly as pillar industry of the country. Because the digitization and information technology are widely applied, the electric network development shows the scale and intellectualized characteristics. On the one hand, the function of resource optimizing configuration is improved by the large electrical network interconnection, on the other hand the affecting scope of electric network fault is expanded. The national economy and social stability are influenced very much by the fault. Since the 1960s, many cataclysm power system faults have taken place around the world, caused large economic losses and huge social impact.The fault settlement of electric power system is the extremely complex real-time decision-making process. There are many factors including many uncertainty ones to affect the correct process. Formerly the local decision mainly depends on dispatcher's experience. When the electrical network breaks down, the dispatcher must rapidly and accurately diagnose the fault, give out the corresponding processing measure, restore the normal operation in time, according to the fault information. It is the precondition and foundation that the fault is rapidly and correctly diagnosed. But the modern electrical network is more and more complex; it is very difficult to satisfy the requirements of fault settlement that only depend on the dispatcher's theory knowledge and experience.As the first defense line guaranteeing the electrical network safe and stable run, the microcomputer relay protection takes on the important responsibility to ensure the electrical network and the electric equipment safe. The alternate current and voltage information are turned into the low level digital signal by the A/D transformation. Then the CPUs in the protection device carry out a series of functions according to the protection operating principle, such as data processing, value operation and logical judgment and so on, provide the hard contact information reflecting protection basic survey and the data of protection action.The fault recorder is the important precision equipment to record the electric power system dynamic process. It gathers the current, voltage information and so on, simultaneously cuts in the circuit breaker phase splitting trip information, protection information and pilot protection channel information. The fault recorder has provided the important reference for evaluating relay protection action and analyzing the nature and reason of equipment fault.The fault information management system has established based on the interconnection of microcomputer relay protection and digital fault recorder. It has realized that the protection, fault recorder and switch act information are quickly sent to the dispatch. And it has provided a supporting platform for the scientific analysis of all kinds of fault information, realized fault intelligent diagnosis and the assistant decision-making.The relay protection fault information management system design of Jilin Province 220kV electric network adopts tri-level frame including master station, centralized control station and substation, uses ATM as the data transmission channel. The master station is located at Jilin dispatch center. The centralized control stations are set up at Siping, Tonghua , Yanbian, Changchun, Jilin, Liaoyuan, Baicheng and Baishan local dispatch. The substations are situated at 54 220kV substations managed by Jilin Province dispatch center.The communication system is made up by two ATM virtual special net, each 220kV substation has two 10M Ethernet interfaces, each centralized control station has two 10M Ethernet interfaces, the master station has four l00M Ethernet interfaces, separately composing the protection and fault record net, they are isolated each other, The separate transmission between the protection and fault record information has been realized. Two kinds of information converge through exchange in master station at last. The information of the relay protection action, run, setting value, operating characteristic and channel, the circuit breaker action, the fault recorder, and so on, which concern the electrical network safe operation in substation, are transmitted to the master station by the information transmission equipments. The comprehensive analysis and use to the substation information has been realized in the master station through the information preservation and treatment.At the information collection and management function, the categoricalness of raw information acquisition and the selectivity of report information are emphasized in the part of substation. Using the ability which wavelet transform can detect the fault signal irregularity, the data of the fault recorder has been analyzed. It has realized the fault time detection, the identification of line fault nature and the protection action, the selective upload information.The fault diagnosis is the most important function in the electric network fault information system. It analyzes the various action signals of circuit breakers and protection devices, the electrical quantities measurement of voltage, current and so on in the substation. According to the open circuit breaker and the action logic of protection, the position and type of the fault can be concluded. In order to enhance the reliability and accuracy of the electric network fault information management system and deal with a various of electric network fault correctly, a kind of layering fault information processing and diagnosis method is proposed and has been realized in the system combinating the facts of Jilin electric network.To the online fault diagnosis of the complex electric network fault, the protection and circuit breaker don't correctly act at the same time, the paper presented that apply the information theory to deal with the fault messages. It is the information movement process that the protection and circuit breaker act when the electric power system breaks down. An essence of information movement is uncertainty, lying lots of random information. Therefore, the intelligent electric network fault diagnosis based on information theory can be a good reaction of the uncertainty between fault and indication, improve the reality and accuracy of fault diagnosis. The power system online fault diagnosis methods based on information theory, can give the probability distribution of many possible solutions in the decision result. The master station intelligent diagnosis and aid decision-making has been realized by the way of synthesis application of the expert systems and information processing technology. And the rapidity and accuracy which the dispatchers deal with the fault has been greatly enhanced. This system plays a vital role to ensure the electric network safe and stable operation.