Research On Single-phase Installation Method Of Parallel Gap In 35kV Overhead Line

The 35kV overhead line occupies an important position in the distribution network.As an important part of power supply to users,its safety is the top priority to ensure the reliability of power supply.Most of the 35kV overhead distribution lines in my country use bare conductors,and the power supply area is large.Compared with the 10kV line,the tower is higher,the lightning protection configuration is less,and the lightning tripping rate is higher.In the 3 5kV overhead line,lightning protection measures are divided into "blocking" type lightning protection measures and "draining" type lightning protection measures.The installation of parallel gaps is a typical "drainage" type lightning protection measure,but the traditional method is to install three-phase at the same time,which reduces the lightning resistance level of the line.This paper takes the parallel gap as the research object,and analyzes the influence of lightning directly hitting the tower,the shielding line,and the induction lightning on the 35kV overhead line.That is,when the line is not installed with lightning protection wire,the parallel gap is uniformly installed on the highest phase of the line,and when the lightning protection wire is installed on the line,the parallel gap is uniformly installed on the same side phase.Theoretical analysis shows that this installation method can improve the lightning resistance level of the line by using the tripping mechanism of the 35kV overhead line phase-to-phase short circuit and the coupling principle between the line overvoltage wave.Through the lightning impulse withstand voltage test,relevant insulation coordination methods and requirements of regulations,the interval of parallel gap discharge voltage and gap distance is determined.In order to obtain the effect of single-phase installation parallel clearance on the lightning resistance level of 35kV overhead line,the EMTP-ATP simulation software was used to build a lightning strike simulation model of 35kV overhead line,and the model parameters were set according to relevant data.When the grounding resistances are 25Ω and 10Ω,respectively,the parallel gap can improve the lightning resistance level of line induced lightning and lightning strike towers in the case of no,single and double lightning protection lines.The calculation results show that:(1)When the line has no lightning protection line.When the grounding resistance is 25Ω,the lightning resistance level of the line’s counterattack can be increased by a maximum of 71.2%,and the lightning resistance level of the induction lightning of the line can be increased by a maximum of 73.3%.When the grounding resistance is 10Ω,the lightning resistance level of the line’s counterattack can be increased by a maximum of 81.9%,and the lightning resistance level of the induction lightning of the line can be increased by a maximum of 68.2%.(2)The case of installing a single same line in parallel with a gap and a single lightning protection line.When the grounding resistance is 25Ω,the lightning resistance level of the line’s counterattack can be increased by a maximum of 28.2%,and the lightning resistance level of the induction lightning of the line can be increased by a maximum of 42.5%.When the grounding resistance is 10Ω,the lightning resistance level of the line’s counterattack can be increased by a maximum of 21.2%,and the lightning resistance level of the line’s induction lightning can be increased by a maximum of 50.2%.(3)The case of installing a single same line in parallel with clearance and double lightning protection lines.When the grounding resistance is 25Ω,the lightning resistance level of the line’s counterattack can be increased by a maximum of 13.1%,and the lightning resistance level of the line’s induction lightning can be increased by a maximum of 43%.When the grounding resistance is 10Ω,the lightning resistance level of the line’s counterattack can be increased by a maximum of 11.1%,and the induction lightning resistance level of the line can be increased by a maximum of 38.4%.The method of installing parallel gaps on a single phase of a 35kV overhead line has a significant effect on improving its lightning resistance level,enriching the lightning protection methods for 35kV overhead lines.