A study on high-voltage substation ground grid integrity measurement

• A modified high-current method for testing the integrity of the grounding grid is proposed.
• Quite different from conventional HCM, the modified HCM is an objective test method.
• Power system frequency and its harmonics interference do not affect the measurements.
• The field test results were presented and details analyzed.

The condition of the substation grounding grid is vital for the safety of the people. Inadequate grounding may cause failures in major substation's equipment, as well as in control, metering and telecommunication equipment. Therefore, it is necessary to clearly identify damaged elements on grounding grid. This paper presents an approach to test the integrity of the grounding grid in a general framework of IEEE Std. 81-2012. More precisely, in order to locate damaged grounding riser(s) and/or grounding grid conductor(s), this paper is focused on novel unambiguous criteria for post-processing of raw-data collected from the measurements. In order to avoid the effect of power frequency interference on the measurement, we use DC test current of 100 A. The field test is described and discussed in details. The outcome of field test clearly shows the validity and feasibility of the proposed approach.