Research On Fault Diagnosis Method For Distribution Network With Distributed Generation Based On Petri Net

The distribution network connects the transmission system and power users as a bridge, rapid and effective distribution fault location method plays an important role in ensuring power quality and improving the system reliability, and it is also the premise of fault isolation and supply restoration. Artificial intelligence algorithm is a common method in the fault diagnosis field, describing the true concurrency accurately is the unique advantage of Petri net theory. Most of the existing power grid fault diagnosis methods based on Petri net are aimed at transmission network,which are usually based on the relay protection of power transmission network and the action message of the circuit breaker to model, they are not suitable for the distribution network.Based on the structure and operation characteristics of distribution network, this thesis proposes a Petri net modeling method based on FTU (Feeder Terminal Unit)fault information. First of all, the Petri network model with inhibitor arcs and probabilistic information measure is defined, the introduction of inhibitor arcs greatly enhances the simulation ability of network system. The probabilistic information measure can be used to select the highest confidence solution in the uncertain event. Secondly, this thesis introduces the function of feeder automation terminal and the fault diagnosis theory based on FTU fault information. With the comprehensive utilization of the FTU over current signal and amplitude measurement information, the speed ability and fault tolerance of the proposed method are achieved. The fault criterion based on wavelet analysis of fault transient components can solve the problem of unobvious steady-state fault information of the single phase to ground fault in the small current grounding system. According to the topology characteristics of the distribution network, a hierarchical fault diagnosis metihod is adopted. The fault feeder, fault unit and fault section are diagnosed in order.Finally, the general Petri net of the distribution network fault diagnosis is improved, and the principle of fault diagnosis in distribution network with distributed power supply is analyzed. The terminal coding method considers the value and direction of the fault current,which makes the improved model keep consistent with the general model. With the fault diagnosis of a typical example,the effectiveness and feasibility of the proposed method is proved.