变电站接地网的暂态分析方法综述

Survey on Methods for Transient Performance Analysis of Substation Grounding Network

介绍了用于变电站接地网暂态分析的4种方法:电路法、电磁场法、场路结合法和传输线模型法,分析了各方法的基本原理、适用的工程条件、需要解决的问题和发展方向。电路法模型简单,可以兼顾土壤放电的非线性特性以及接地导体之间的相互耦合作用,但仅适用于暂态电流频率为几百kHz以下的情况;电磁场分析法基于天线理论,算法精度较高,但计算量较大,在处理地网参数的时变性方面有困难;场路结合法能够对接地网和地上电网统一建模,降低了计算量,在1MHz的暂态电流频率范围内可以满足工程精度要求;传输线法计算效率较高,在处理干扰传递耦合相关问题方面有很好的前景,但难以确定兼顾时变和频变特性的地网导体参数。

Four methods for transient performance analysis of substation grounding network, i.e., the circuit method, the electromagnetic field method, the field-circuit method and the transmission line model method, are presented, meanwhile the basic principles, applicable engineering conditions, the problems to be solved and development trend of these methods are analyzed. The model of circuit method is simple and can consider both nonlinear discharge characteristic of soil and intercoupling among grounding conductors, however it can be only used for the circumstance that the frequency of transient current is below several hundred kilohertz; the antenna theory based electromagnetic field method is more accurate, but the calculation amount is large and it is difficult while the time variation of parameters of grounding network is processed; using field-circuit method, the unified modeling of both grounding network and power network above ground is possible and from this the calculation amount can be reduced, and yet only within the frequency range up to 1MHz this method can meet the precision requirement in engineering when the allowable upper frequency limit of transient current is 1MHz; high computational efficiency is the advantage of transmission line model method that has good prospect in project application, but it is difficult to decide the parameters of conductors consisting of grounding network while both time-varying and frequency-varying characteristics should be considered.