Grid Fault Diagnosis Based On Improved Petri Nets

Along with the construction of UHV power grid, the interconnection of regional grid and the development of AC-DC hybrid grid, on the one hand the whole grid electrical connections are becoming increasingly closer, on the other hand the complexity of grid operation and the power quality society required are getting higher and higher, coupled with the impact of meteorological conditions and human factors, grid fault occurs inevitable.In the face of massive alarm information after the grid fault, quickly determine the fault correctly is very difficult for dispatchers, especially in the event of complex chain failure, incorrect relay protection and circuit breaker operation and the alarm information is lost or wrong, it will be more serious. Therefore, it is necessary to research an efficient grid fault diagnosis system using various types of alarm information, to quickly and accurately identify the faulty equipment, exclude interference of non-fault equipment, help dispatchers to make decisions.In this paper, after making full use of the advantage of Petri net to describe the order and parallel event and the advantage of matrix calculation, the fuzzy reasoning rule when the automatic devices are refused to action is improved, the weighted fuzzy reasoning Petri net and matrix arithmetic reasoning process considered inhibition input are defined, and then proposed the hierarchical weighted fuzzy reasoning Petri net grid fault diagnosis' modeling and fault diagnosis method considered the circuit breaker failure protection. And then demonstrated the effectiveness of the method through different examples.To improve the accuracy of fault diagnosis and exclude the interference of non-real faulty equipment, the timing characteristics of alarm information is inteoduced, a hierarchical timing weighted fuzzy reasoning Petri net(TWFRPN) grid fault diagnosis method based on the event starting point is proposed, not only solved the difficult problem when building the rules of alarm information' mutual timing verification, we can also get the failure time of equipment, therefore, the fault logic is clear and is easy to explain the failure process, the diagnosis result is helpful to dispatchers to make decisions. Then verified the effectiveness of the method through different grid fault cases, the method can improve the real faulty equipment place' confidence level while reducing the non-real faulty equipment place' confidence level, thus improving the accuracy of fault diagnosis.To solve the problem of fault diagnosis result is not clear even wrong when the key alarm information is missing,a hierarchical timing weighted fuzzy reasoning Petri net grid fault diagnosis method combined wide area information based on information fusion technology is proposed, it combined the protection and circuit breaker alarm information from SCADA system with the wide area measuring information from the WAMS system in the data layer, while confirming the information, supplemented the missing alarm information, made full use of the information redundancy of different sources of information, improved the accuracy and fault tolerance of fault diagnosis. The fault diagnosis method proposed can handle complex fault, automatic device refusing or wrong act and the case of alarm information is missing or incorrect. And by the actual fault cases to verify the validity of the method. Then demonstrated the effectiveness of the method through actual grid fault cases.