| Chinese economy is growing day by day,and social electricity consumption is increasing year by year.However,provinces with surplus electricity consumption are often far away from provinces with electricity load,so it is necessary to increase the transmission capacity of power grid.The transmission lines with multiple circuits in the same tower are widely used for their strong transmission capacity and high cost performance.Compared with single-circuit transmission lines,fault location and identification of multiple-circuit transmission lines are more difficult,so it is necessary to make an in-depth study on them in order to ensure the power demand of society.In this paper,based on the non-contact current measurement method,by analyzing the fault current characteristics of multi-circuit overhead transmission lines,a fault location and identification method for non-contact multi-circuit overhead transmission lines on the same tower is constructed.Firstly,the optimal layout method of magnetic measurement array is studied.According to the electromagnetic relationship,the magnetic array is designed,the transmission line is simplified as a wireless long straight wire model,and the electromagnetic relationship equations of n measuring points in the magnetic array about n phase current are constructed by Biot-Savart law.When the condition number of coefficient matrix is smaller,the influence of geomagnetic field,external interference and errors generated in instrument measurement is lower,and the current information is closer to the real solution.Improved particle swarm optimization algorithm is used to optimize the minimum coefficient matrix condition number,and the optimal magnetic array is solved.Secondly,the fault current characteristics of multi-circuit transmission lines on the same tower are analyzed.According to the basic principle of circuit analysis,the fault current characteristic analysis method based on transmission line load and load size is established,and the double-circuit line model is built on Matlab,and the current waveforms at different faults are simulated to verify whether the analysis results are satisfied.Thirdly,a fault location and identification method for multi-circuit transmission lines on the same tower is proposed.According to the consistency of current and magnetic field information,combined with non-contact current detection method and fault current characteristics,fault location and identification are realized by the change characteristics of magnetic field information.Finally,the proposed and related methods are verified on double-circuit lines.Under different magnetic arrays,the current solutions with the same noise in the same operating state are solved,and the influence of preprocessing of equations on solving real solutions is verified.The fault is analyzed by adding different noises,and verified by simulation on Ansys Maxwell.The double-circuit line platform is built for experimental verification,and the verification results prove the feasibility of the method. |
