Research On Fault Diagnosis Of Transmission And Distribution Network Based On Intelligent Algorithm

Automatic and accurate fault diagnosis is the foundation of developing self-healing grid(SHG)in the future.In case of a power grid fault,fault diagnosis is able to accurately locate a fault in power grid and to identify the correct relaying action under all kinds of complex situations such as the loss and distortion of fault information,and the breaker rejecting and false tripping,so that reference information can be provided for varied power dispatching personnel,and maintainers.Meanwhile,various electrical quantities and switching quantities of the power system can be acquired in real time thanks to the development and improvement of the system such as SCADA,RPMS and WAMS.It provides a solid foundation for the research and implementation of fault diagnosis.Work and achievements made in this paper include:Firstly,the concepts of fault diagnosis of transmission and distribution network are studied.On this basis,the typical topological structure and relay protection mode of transmission and distribution network is selected as key research subject and considered as a breakthrough to investigate the actual relay protection scheme and the relationship between signals such as relaying exit signals and switching exit signals in failure,thereby making necessary preparation for the subsequent fault diagnosis.At the same time,this paper introduces the basic concepts of Petri net and weighted fuzzy Petri net,discusses the advantages of weighted fuzzy Petri net in the fault diagnosis of transmission and distribution network,and lays a solid theoretical foundation for the fault diagnosis method of transmission and distribution network based on improved weighted fuzzy Petri net proposed in the following chapters.Secondly,a new type of hierarchical transition-weighted fuzzy Petri net fault diagnosis model is designed for transmission grid based on the traditional weighted fuzzy Petri net with the principle of hierarchy and directivity of the relaying actions in case of a fault,the Gaussian distribution coefficient,and the actual relay protection scheme of transmission grid.In this way,a fault can be accurately located when complex fault situations such as multiple faults,information loss and distortion,relaying and circuit breaker rejecting and false tripping occur in the model.Besides,a new topological structure is also designed to prevent false detection caused by faults in the dead zone.Finally,a method of reverse search that can automatically report abnormality of related relaying and breakers is designed in line with the model.This fault diagnosis model has simple principle and accurate results.When the fault occurs,the fault report can be quickly and automatically generated with a relatively-high tolerance.This is helpful to the fault detection at the dispatching end and the development of self-healing grid.Thirdly,considering the time sequence characteristic of distribution network relay protection is more obvious than transmission network,introduce a connection rule of time sequence.Through this,a timing-weighted fuzzy Petri net(TWFPN)fault diagnosis model is designed for the distribution network based on the hierarchical transition weighted fuzzy Petri net(WFPN)fault diagnosis model for the transmission network,through which values of initial library and transition in the WFPN fault diagnosis model and the structure of the WFPN fault diagnosis model can be optimized in accordance with the actual operation of the relay protection of distribution network.Moreover,the connection rule of time sequence is also introduced to increase the logic and tolerance of fault diagnosis by the proposed method considering that certain time-sequence setting conditions should be satisfied in relay protection and breaker outlet between various hierarchies of the relay protection of the distribution network.Finally,a reverse search method that can automatically present a simple report concerning the fault of relay protection and breakers related to components is also designed as per the TWFPN model.The quick-response and accurate fault diagnosis method that meets the fault diagnosis requirement of distribution network can be applied to both traditional distribution network with open-loop operation and active distribution network with closed-loop operation only by modifying the element settings of initial library and set B in corresponding direction,which is conducive to the development of distribution network and UEIOT(Ubiquitous Electric Internet of Things).