| China’s power system,10kV overhead distribution lines have low insulation level,wide distribution range and high lightning trip rate.Comprehensively improving the lightning resistance level of 10kV overhead distribution lines is the key to improving the stability of the power system.Preliminary studies have shown that the addition of a parallel gap with a single same-line installation method can effectively improve the lightning resistance level of 10kV overhead bare conductor lines.However,the current research on application effects mostly relies on simulation calculations,and is only for 10kV single-circuit overhead lines.There are still problems of matching the number of parallel gaps,installation positions and discharge voltage values in multi-circuit lines.Therefore,from the perspective of theoretical analysis,this paper further studies the principle of improving the lightning resistance level of 10kV overhead lines with single-phase installation of parallel gaps,and studies the optimization method of parallel gap installation of multi-circuit lines.Taking the double-circuit line as an example,the application method of the single-phase installation parallel gap in the overhead line is calculated.In this paper,the single-conductor coupling model of the application of parallel gaps in 10kV overhead lines is firstly constructed,the coupling mechanism of single-phase installation of parallel gaps is analyzed,and the principle for improving the lightning resistance level of 10kV overhead lines is studied,and then the parallel gaps are constructed in multiple 10kV overhead lines.The multi-conductor coupling model of,obtains the calculation method of the coupling overvoltage suppressed on the remaining lines when the parallel gap is installed on the m wires in the n-conductor system.Using the improved ATP-EMTP of MODELS,a simulation model of lightning overvoltage of 10kV overhead distribution line is built,and it is verified that the theoretical quantitative calculation method and the simulation calculation method have high equivalence.ATP simulation studies the problem of the application method of parallel gaps on multi-circuit lines.For the 10kV multi-circuit line on the same tower,the installation positions,number of installations and the setting of the gap discharge voltage of the parallel gap are various,and there are many combinations,and the coupling method between the lines is more complicated.The difficulty of application is much greater than that of a single-circuit line.For multi-circuit 10kV overhead lines,considering three factors that affect the lightning protection effect of single-phase installation of parallel gaps on multi-circuit lines,the number of parallel gaps installed,discharge voltage and installation position are considered,the configuration method of parallel gaps for single-phase installation is analyzed,and the results are obtained.The calculation process of the lightning resistance level of the line under different parallel clearance installation methods.Taking a double-circuit line as a calculation example,when the line suffers from induced lightning overvoltage,it is recommended to install a parallel gap on the highest phase of each circuit.Compared with no parallel gap installed,the lightning resistance level of induced lightning can be improved by up to 148%;When the line is subjected to direct lightning overvoltage,the lightning protection effect of only installing one-phase parallel gaps on the highest phase of the first circuit is better than other installation methods.Compared with no parallel clearance installed,the lightning resistance level of lightning strike towers can be improved by 62.5%-75.2%,and the lightning resistance level of lightning strike lines can be improved by 12.2%-69.1%.The results obtained in this paper provide theoretical support for the lightning protection method of single-phase parallel clearance,provide method guidance for the application of single-phase parallel clearance in lightning protection of 10kV multi-circuit overhead lines,and are of great significance for improving the safe and stable operation of distribution networks. |
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