New Gold – Grounding System Analysis

Project Summary

Our team provided a grounding system analysis to ensure personnel safety and regulatory compliance under fault conditions. This included field testing, advanced modeling, and simulation of substation grounding systems and surrounding infrastructure. The scope of work included:

• Conducted soil resistivity testing on site using the Wenner 4-pin method in accordance with IEEE Std 81 to characterize the subsurface soil conditions.
• Inverted the measured soil resistivity data utilizing the CDEGS RESAP module to obtain equivalent multi-layer soils to be utilized in the grounding analysis.
• Create a detailed HIFREQ model of the grounding system including the substation ground grids, distribution lines, transmission lines, building foundations and peripheral ground loops, water pipes, gas pipes, and any buried metallic structures in the vicinity of the grounding system.
• Performed on-site Fall-of-Potential (FOP) testing for validation of the grounding model utilizing an Omicron CPC 100 for the fault current injection along with a CP CU1 for coupling of the test set to the 230kV tie line for the fault current injection path.
• Simulated the FOP test using the HIFREQ grounding model in conjunction with the detailed multilayer soil model(s) to validate the grounding model. The simulation accounted for the magnetic field induction between test leads and nearby conductive elements such as transmission and distribution line ground return conductors, grounding grid conductors, metallic, and other buried metallic structures. Additionally, conductive coupling effects between the test electrodes, the grounding system, and adjacent conductive structures were incorporated.
• Developed equivalent Three-Phase sources for the Kenora and Fort Francis 230kV source terminals based on the fault current contribution data supplied by Hydro One. 
• Modelled the Main Substation 230kV to 13.8kV transformers to account for the 230kV Wye solidly grounded neutral connections in the fault current distribution calculations.
• Energized the HIFREQ model with the equivalent Three-Phase sources and simulated single-line to ground faults at the Main and Tie substations.
• Analysed the performance of the Main substation, Tie substation, and UG substation grounding systems (i.e. step/touch potentials, ground potential rise, transferred potentials.
• Summarized tolerable safety limits for step and touch voltages in accordance with IEEE Std 80.
• Evaluated the performance of the grounding systems against applicable safety standards.
• Reviewed compliance of the UG substation grounding system with the requirements of CSA M421 “Use of Electricity in Mines”.