Research On Micro Power Grid Fault Diagnosis Using Hierarchical Weighted Fuzzy Petri Net

With environmental problems and energy crisis being increasingly serious, the micro grid technology has been widely concerned. Micro power grid solved supply problems about the large-scale access of distributed power in the distribution network, improved the efficiency of power grid. Compared with big power grid, the grid topology structure is flexible, and the power supply is randomly thrown back and the power of uncertainty; Most of the micro grid belong to power users, lack of the professionals’ manipulation, mainly reliing on automated information system for autonomous operation and management. On the variability of the micro power grid, how to build a general micro power grid fault diagnosis model, has become an important problem for guaranteeing the micro power grid reliable operation.This article selects the Petri net model for power grid fault diagnosis tool, In the process of fault diagnosis, Petri net is based on the protection of information modeling analysis. and for consists of micro grid inverter power supply, as a result of the limitation capacity of the inverter unit, the short circuit current is not more than 2 times of the rated current, thus the traditional three-step protection is no longer applicable. Based on this, this paper researches a method suitable for different micro power grid operation mode, which is based on the phase differential protection of the positive sequence fault current component, greatly improving the sensitivity of protection in the micro power grid, providing accurate information for Petri net library in the fault diagnosis.To the flexible structure topology in the micro grid, this paper established a hierarchical Petri nets model about micro grid circuit fault diagnosis. The model used hierarchical protection set to process micro grid protection information, by updating the protection set information to solve the modeling problem when the micro grid topology changed, with the strong adaptability for the flexible micro grid. The model can effectively distinguish protection and circuit breaker’s refusing action and error action and the protecting data for the temporal relations are dealt with. And to make full use of the protection information, enhancing the diagnosis system of fault tolerance, the weighted fuzzy Petri net theory is applied to the hierarchical Petri model, using the BCC algorithm adaptive cumulative value, which improved the accuracy of diagnosis. The simulation results verify the validity of the theory in this paper and higher accuracy.