Induced Voltage and Current Simulations, Safety Criterion, and Mitigation for EHV Transmission Lines in Close Proximity

One of the benefits of double-circuit transmission lines is that line maintenance work can be performed on a de-energized circuit while the other circuit remains energized. However, induced voltages and currents can be generated on the de-energized line due to electrostatic and/or electromagnetic coupling effects and the close proximity to energized conductors. In order to mitigate the safety concern related to high induced voltages or currents, line discharging grounding switches (LDGS) may be installed. Since this can be an expensive solution, the magnitude of induced voltage and current is the key for defining safety criteria to judge whether or not a costly mitigation plan is needed. This paper presents the theory of induced voltage and current and a sensitivity analysis of influential parameters that impact each. In addition, a safety criterion using arc reach calculation is proposed to determine when LDGS are required. A case study is included.