计及回流电流和分流电流影响的接地参数分析计算

Analysis and Calculation of Grounding Parameter Considering the Effect of Return Current and Partial Current

在以往的接地参数计算中,直接将站内和站外不对称短路时的最大入地短路电流从接地网边角注入来计算各个接地参数,而忽略了短路过程中形成的回流电流和分流电流,这造成某些接地参数计算误差较大。本文以某电站的短路电流分布为例,计算分析了回流电流和分流电流对接地参数计算的影响,并研究了在计及回流电流和分流电流的情况下各个敏感因素对接地参数的影响。研究表明:计及回流电流和分流电流后,GPR会增大一定的幅度,但电位梯度和网内电位差相比只考虑入地短路电流时会增大很多,地表电位不均衡程度大大增大,接触电势和跨步电势也相应增大。在接地网设计与评估时,需慎重考虑回流电流和分流电流对地表电位分布的影响。

In the former calculations of the grounding parameter, the maximum ground fault current in the inside and outside short-circuit current calculations is directly inject into the corner of the grounding grid, ignoring the return current and the error of some grounding parameters is big. partial current forming in short process, which caused Using the short-circuit current distribution of a certain power plant as an example, the influence of return current and partial current on the grounding parameters, and studied on the influence of the sensitive factors on the grounding parameters in consideration of the return current and partial current are calculated and analyzed. The researches show that in consideration of the return current and partial current, GPR will increases a certain extent, but potential differences within grounding grids will increase a lot compared with the potential differences within grounding grids only think about the ground fault current, also the imbalance degree of the surface potential increases greatly, and contact potential and step potential increase accordingly. Designing and evaluating grounding grid need carefully consider of the influence of return current and partial current on the surface potential distribution.