The Influence Rule And Position Optimization Of Overhead Ground Wire On Lightning-induced Voltage In Distribution Network Using FDTD Method

The insulation level of distribution network is low,and it is easy to be attacked by lightning,resulting in distribution network trip,wire break,insulation equipment damage and other faults.Lightning induced voltage is the main factor of lightning fault in distribution network.The protection of lightning induced voltage has become the focus of lightning protection in distribution lines.The installation of overhead ground wire can effectively suppress the lightning induced voltage and improve the lightning protection level of distribution lines.It is of great theoretical significance and engineering application value to study the influence rule and configuration optimization of overhead ground wire on lightning induced voltage,so as to ensure the safe and reliable operation of distribution network and improve the power quality of customers.Aiming at the influence law of overhead ground wire on lightning induced voltage of distribution network and the optimization problem of ground wire configuration,this paper establishes the calculation model of overhead ground wire lightning induced voltage by FDTD,carries out the research on the influence law of overhead ground wire on lightning induced voltage,and puts forward the optimization suggestions for the position of overhead ground wire.The main work of this paper is as follows:(1)Based on the transmission line theory and electromagnetic field propagation theory,the calculation model of lightning electromagnetic field is established by using the finite-difference time-domain method.The model can accurately simulate the lightning current waveform and electromagnetic field propagation process in the free space in the lightning return channel,and can realize the calculation of lightning electromagnetic field under the ground complex parameters.By changing different model parameters,the lightning electromagnetic field in free space is calculated,and the influence law of lightning electromagnetic field is summarized and analyzed.(2)Based on the field line coupling mechanism of Agrawal,the finite-difference time-domain method is used to realize the calculation and modeling of lightning induced voltage of single conductor and multi conductor,which verifies the accuracy of the model and can dynamically calculate the lightning induced voltage of single conductor and multi conductor.Based on the above model,the influence factors of lightning induced voltage on the conductor are simulated,and the influence laws of earth conductivity,lightning return speed,lightning current amplitude and conductor space position are analyzed.(3)Based on the Agrawal multi conductor field line coupling method,the model of overhead ground wire is established,and the calculation model of lightning induced voltage of single circuit and multi circuit distribution lines is established based on the actual working condition parameters of distribution lines.The calculation of coupling effect of overhead ground wire under different installation schemes is realized,and the waveform characteristics of lightning induced voltage on each phase of conductor after the application of overhead ground wire can be obtained Compared with the peak suppression effect,the paper puts forward the optimization proposal of the position of the overhead ground wire in the distribution network.The above research work can provide theoretical basis and optimal position scheme for the application of overhead ground wire lightning protection in distribution network,guide the transformation of overhead ground wire project in distribution network,and have important significance for the establishment of induction lightning protection system in distribution network.