Mas With Colored Petri Net Applied Research In The Distribution System Fault Diagnosis

The fast development of the power system causes the user's request to the reliability of the power supply becoming higher and higher, and the fault diagnosis for distribution network is especially important. If we can judge the fault section, then isolate it quickly and restore the power supply promptly, the reliable indexes for power supply will be enhanced greatly and the users' request of the power quality will be ensured. The research on fault diagnosis for distribution network is one of the current research's hot spots. Multi-agent system (MAS) is a distributed artificial intelligence method, and it is used in this paper to research the fault diagnosis of the distribution network. The software platform constructed by MAS is used to complete the fault diagnosis for distribution network and the colored Petri net (CPN) is used to judge the fault section and restore the fault.The study and the main achievement of this paper as follows:1．On the base of analyzing the distribution management system (DMS), the distribution automation system (DAS) and the distribution network fault diagnosis (FD) thoroughly, this paper points out that the fault diagnosis for distribution network should be completed by way of synthesizing several methods. The MAS, which uses the distributed method to solve problems, adapts to solve the large-scale network distributed problem, such as distribution network. The mathematical expression and the graphical expression of the Petri net can describe the fault diagnosis process. Therefore the CPN method is used in this paper to judge the fault section. The diagnoses' result is introduced in the distribution network fault diagnosis platform which is based on the MAS, and the further fault isolation result can be obtained. Then the CPN method is used to achieve the fault restoration and the fault restoration strategy is exported through the MAS platform at last;2．This paper proposes a method of distribution network topology analysis based on geographic information system (GIS) after analyzing the characteristic of distribution network topology structure and considering the reality that GIS is used in the distribution network widely. This model can solve the commercial GIS but it cannot solve the problem of distribution network topology analysis. We can obtain the distribution network node description model by way of corresponding the power equipment's topology analysis nodes and the commercial GIS's. Moreover we can verify the model's feasibility in virtue of calculating an example;3．By means of the GIS node description model, the GIS node model is transformed into the organ-switch model according to the node organ's electrical attribute. This paper proposes distribution network basic topology analysis unit based on the CPN according to the characteristic of the organ-switch model topology analysis. The distribution network is transformed into the connection between the organ and the switch in this unit. We can obtain the different subsystems in view of the different questions by means of describing the switch's connection situation and then the subsystems are further analyzed to elicit the relevant conclusion. This paper proposes the structure definition of the topology analysis unit based on CPN, the program frame and main function's description;4．We can use the distribution network's basic CPN topology analysis unit to judge the distribution network fault section and here the subsystem is defined with the combined elements which are connected by different state's switches. Because CPN is connected with GIS, the data's structure is simple and data's content is integrated. We can get the correct conclusion after judging the simple fault and the complex fault section in an example. For the switch information contained the false fault information, we also can obtain the correct conclusion finally after correcting the voltage's distributed situation. After isolating the fault section, we can carry out the fault restoration operation;5．Based on analyzing the principle of fault restoration, we can obtain the conclusion that the fault restoration's process of distribution network is the load's redistribution process. Therefore the basic topology analysis unit based on the CPN is introduced into the fault restoration of distribution network. The distribution network's fault is restored according to the heuristic rule, and the detailed implement process used heuristic rule relays on the basic topology analysis unit based on CPN. The subsystem is defined with the load combination which satisfies the condition of the fault restoration. This algorithm is simple and the result is clear. We can obtain the correct result after the simulation experiment for the actual distribution network;6．This paper proposes the DMS model based on MAS, and the contract net is used to realize the alternation between each Agent because the situation that each Agent model is fixed when it alternates and the Agent participating in the alternation is less. According to the distribution feature of the distribution network, this paper uses MAS to construct the distribution network fault diagnosis software platform, and each Agent model's function in the platform is presented in this paper. The realization method of fault diagnoses Agent is introduced in detail. This Agent uses the FIPA system structure and the multi-thread technology to realize block blackboard interactive model. This paper produces the main function and each Agent function's concrete function according to the main body procedure frame using to realize the fault diagnosis Agent.