Research On Fault Location Of Power System Based On Phasor Measurement Unit

With the increasing scale of power systems,their control and protection systems are more complex,and the probability of the increasing scope of localized faults increases.The improvement of power grid fault diagnosis capabilities is an important guarantee for the safe and stable operation of power systems.The wide-area measurement system(WAMS)based on the Phasor Measurement Unit(PMU),enables on-line simultaneous measurements under the grid operation conditions,which creating conditions for real-time fault diagnosis across the entire network.This paper aims to promote the application of WAMS and PMU in the field of fault diagnosis of power grids and study the fault location algorithm based on PMU.After the prospects for the development of WAMS and PMU,the principle of composition,advanced applications,and the modern power system based on PMU/WAMS are analyzed and summarized,and the configuration features of PMU in the field of fault analysis are thoroughly analyzed.Then based on the idea of decentralized control of modern power systems,the overall framework of power system fault diagnosis based on finite PMU is proposed,and the algorithm's positioning accuracy and fault diagnosis performance have been verified in detail.The main research results can be summarized as the following parts:1.Based on the decentralized control theory,the basic theory of cluster analysis is studied,the common methods and specific steps of pedigree cluster analysis are analyzed and compared.Base of the condition that the electrical distance between nodes in the power system can directly reflect the characteristics of the degree of electrical contact between nodes,the minimum distance method is selected to analyze and discuss the power system.2.A power system partitioning method based on the PMU optimization configuration and the theory of cluster analysis is proposed.The relationship between the observability of the system and the placement of the PMU is studied at first.To meet the fault observability of the system,the PMU interval bus configuration scheme is selected,which the rationality of its application in the field of fault diagnosis has been verified.Then combining the PMU optimal configuration with the pedigree clustering method,a power system partitioning method is proposed,and the examples are illustrated in the IEEE39 node system.3.The overall fault diagnosis framework of power system is elaborated,and a multi-terminal fault location algorithm based on limited PMUs and lumped parameter model is proposed.After the subsystems are divided,the subsystem fault probability index index P is proposed to identify the faulty subsystems.Using the method of descending order of subsystems according to the value of P,the possibility of internal faults of the subsystems ares characterized.Then faults are searched sequentially for each subsystem.The search will be stopped when their are two consecutive subsystems are found no faulty,which could reduce the amount of fault diagnosis for other non-faulty subsystems and improving the efficiency of the algorithm.When locating faults in subsystems,a multi-terminal fault location algorithm based on limited PMUs and lumped parameter model was proposed.Only the fault component of the bus positive sequence voltage is used to establish the impedance-type node equation to overcome the influence of current transformer saturation.The algorithm is easy to implement,and the calculation is small.The simulation confirms its accurate.And it is not affected by the type of fault,the system structure,the transition resistance and the saturation of the current transformer.The fault location can be realized in the absence of some PMU information,and under multiple faults.4.A multi-terminal fault location method based on limited PMU and Bergeronmodel is proposed to improve the overall framework of system fault diagnosis.Taking into account the influence of distributed capacitance on transmission lines and combined with the PMU configuration,a faulty line multi-terminal positioning formula based on the Bergeron model is constructed and verified by simulation.Then the two fault location algorithms based on the Bergeron model and the lumped parameter model are compared through simulation analysis,and it is found that the positioning accuracy of the method based on the Bergeron model is higher,and the algorithm based on the lumped parameter model can be realized in the absence of some PMU information.Therefore,combining the advantages of the two algorithms,an improved overall fault diagnosis framework of the power system based on the optimized configuration of the PMU is finally obtained.