土壤中先导放电通道仿真模型与干扰特性研究

Underground power or communication cables may be intervened or damaged by lightning or other similar strikes. Therefore studying and modeling the lightning propagation in ground and the corresponding interference characteristics are great meaningful, in theoretical and application aspects, for the designs of ground system, underground cable and the compatibility of electrical and electronic devices connected with underground cables. This project, used new research methods and measures in it, focuses on a numerical model for simulation of leader discharge channels in soils based on the experimental investigation of the mechanisms and characteristics of channels in soils. The research of the project consists of three main aspects as following: ① The characteristics of the leader discharge channels affected by the impulse parameters, type and parameters of soil and buried objects in soil; soil breakdown mechanisms under different conditions; ② A model for simulation of discharge channels in ground; ③ The characteristics of electromagnetic interference and damage to underground cables and the devices connected with the cables. .The achievements of the project include following aspects: 1. The experimental study achievements indicates: ① Transient impedance of discharge channel in soil is governed by the resistivity and moisture content of soil and the parameters of impulse source. Different breakdown mechanisms in dry and wet soils have been found. ② Breakdown channels in dry soils have more tendency to be less-branching single channels with low transient impedance, while the channels in wet soils have more tendency to be more-branching multi channels with high transient impedance.③ Lightning induced over-voltage in a communication cable may be decreased by burying the cable deeply in a soil with low resistivity, setting the cable in a metallic pipe and putting a conducting plate in soil over the cable. 2. Achievements in the numerical simulation: ①The simulation results on transient impedance of breakdown channels, using the principle of energy balance, reflect the experimental observations. ② It has been found that the lightning channel patterns in ground is governed by the local electric field distribution. Based on this observation and the review of existing models, a new numerical model on a probabilistic basis, to simulate the procedure of formation of breakdown channels in soils, has been proposed and realized. The interception of underground cable is considered in the new model. ③ The simulation results using the proposed model may be used to well explain some investigated accidents of underground cables or gas pipelines caused by lightning strikes..The achievements of the project may be used for prediction of lightning breakdown channels in soils, assessment of lightning performance of underground cables and design of suitable protective and mitigating strategies..

研究内容包括：1当大地受到雷电或类似冲击作用时，土壤中先导放电通道特性及其与冲击匦浴⑼寥览嘈陀氩问⒌叵卵诼裉逯涞哪谠诹担煌跫禄鞔┗恚?、土壤中放电通道计算机仿真模型；3、对地下电缆及与电缆相连的电子、电气设备的电磁干扰与危害特浴Ｄ康氖俏喙叵低秤肷璞傅牡绱偶嫒菪陨杓铺峁┛煽康睦砺酆图扑阋谰萦胧导蚀胧