接地网导体腐蚀故障诊断测试方案

为了科学地确定接地网腐蚀故障诊断中的测试方案,提高诊断结果的准确度,在最大电压公理的基础上提出并证明了3个推论并指出,在给定量测位置的条件下,若要使量测电压对某条支路电阻的变化最敏感,则恒定直流电流源必须加在该支路上;当恒定直流电流源加在某条支路上时,该支路两端电压对该支路电阻的变化最敏感。提出了一种将恒定直流电流源分别加在各条本征支路两端同时量测相应本征支路两端电压的理想最优测试方案,该方案是充分的,且具有诊断结果对误差不敏感、抗干扰性强和信号大便于检测的优点;讨论了实际应用中接地引下线自身电阻的问题,并建议了一种次优测试方案。以一个60支路的实验接地网为例进行了验证,结果表明提出方法是正确的和可行的,并且能够提高接地网故障诊断的抗干扰性和准确度。

Test Schemes of Conductor Corrosion Diagnosis for Grounding Grids

In order to determine testing schemes scientifically for grounding grid corrosion diagnosis,based on the axiom of maximum voltage for a resistance grid, three inferences are put forward and proved. It is pointed out that the derivative of a voltage with respect to a branch resistance reaches its highest value when the constant DC current exciter is added on the corresponding branch and that the derivative of the voltage on the corresponding branch is the maximum. A theoretical optimum test scheme is described to implant the constant DC current source on each intrinsic branch and to measure the voltage on the corresponding branch, respectively. It is pointed out that such test scheme is complete and has the advantages of less sensitive to test error, better anti-interference ability and easy measurement due to large voltage magnitude. It is also pointed out that theoretical optimum test scheme faces the problem of the influences of lead lines in the practice. The measures to avoid the influences of lead lines are discussed. An approximate optimum test scheme is suggested. A grounding grid with sixty branches is used as an example. The results of corrosion diagnosis show that the proposed approaches are correct and feasible, and it can remarkably enhance the accuracy of diagnosis results.