接地网腐蚀故障诊断的可测性研究

Testability of Grounding Grids Corrosion Diagnosis

为研究接地网故障诊断的可测性,提出了一种利用接地网拓扑变换的分析方法。将接地网分解为若干以可及节点为边界的元版块,根据电路网络理论削去不可及节点后得到对应的元网络,对所有元网络进行网络综合得到只含可及节点的可及接地网,进一步约简得到可及节点间最多只含一条支路的本征接地网。根据支路电阻的唯一确定性,将支路分为明晰支路和不确定支路两类,给出其判别方法,确定了不确定转化为明晰的原则。根据叠加原理和互易定理,归纳出进行独立激励并获得不重复量测数据的原则,还给出了接地网故障诊断独立方程数目以及获得独立方程的方法。结合一个实例详细说明了所提出的方法并设置了两组代表性故障进行分析计算,结果验证了所提出方法的正确性,并表明接地网故障诊断的可测性是可以预计的,可测性研究对于优化测试方案和科学利用诊断结果具有指导意义。

To investigate the testability of grounding grids corrosion diagnosis, a novel approach using circuit topology transformation was presented. A grounding grid was divided into a set of circuit-blocks bounded by accessible nodes. A block-network was formed by eliminating all the inaccessible nodes from a circuit-block. An accessible grounding grid was worked out by synthesizing all the block-networks, in which only accessible nodes were included. An intrinsic grounding grid was obtained by simplifying the corresponding accessible grounding grid, in which there was no more than one branch between each two accessible nodes. Branches were classified into two kinds such as clear-branches and uncertain-branches in according to the certainty of their resistances. The classification method and the principle of transforming a uncertain-branch into a clear-branch were described. Based on reciprocity theorem and superposition theorem, the considerations of independent excitation and non-repeated testing were discussed. The number of independent diagnosis equations and the way to obtain independent diagnosis equations were given. An example was given to illustrate the proposed approach in detail. A group of typical corrosions were set and analyzed, the results verifies the correctness of the proposed approach, and the testability of grounding grid corrosion diagnosis can be prior-evaluated and it is of great significance to guide the optimization of testing scheme and scientifically utilize the diagnosis results.