Research On Fault Location Of Power Transmission Line

Electricity is an important energy source,which occupies an important position in people's daily life and industrial production.With the development of the national economy,the demand for electricity by power users is also on the increase.The power industry is also increasingly powerful at the same time led to the continuous expansion of the power grid.Nowadays,the length of transmission lines is increasing,and the line structure is also becoming more and more complex.Since the transmission line is an important part of the power system,but also one of the most troublesome parts of the power system,once a fault is found,it is very difficult to find the fault.Therefore,ensuring a reliable and uninterrupted power supply is an important guarantee for meeting the needs of users and maintaining the steady development of modern society.Fault location is the primary work to be done in the event of a power system failure.Accurately locating the position of the fault point helps to quickly repair faults and reduce losses.Based on the research of fault phase selection method which using symmetrical components,this thesis combines the fault phase selection with the fault current distribution coefficient to locate the fault.The main contents are as follows:(1)Based on the detailed analysis of basic principle,the ground short-circuit criterion of traditional phase selection method based on symmetrical components is improved.In the improved criterion,the phase difference between the negative sequence faulty components current phase and its positive sequence phase is used,adding the threshold judgment of the zero sequence voltage component to distinguish the ground-fault from the non-ground-fault,and somehow avoiding the shortcomings of misjudgment as well as simplifying the phase selection process since the zero sequence current distribution factor is not equal to its positive and negative ones in the traditional ground short-circuit criteria.Simulation results show that the improved criterion has high correctness and stability.(2)The improved symmetrical component phase selection method and the fault current distribution coefficient are combined to form a new single-ended fault location method of power transmission line.According to the Kirchhoff theorem of voltage,it establishes location equation on power system equivalent model.Then the symmetrical components of voltage and current from one end of the line are measured.After that,the fault current distribution factor is introduced,and the fault current is replaced by the weighting coefficient of the fault type and increment value of fault current.Finally the fault location function is established and the fault distance is detected.The experimental results show that the method is not affected by the size of the fault resistance,the size of the grounding resistance,the type of the fault,the location of the fault point,and has high stability and feasibility.Compared with the method in the reference,the experiment results show that this method is of more accuracy.