A Novel Calculation Model for Potential Transfer Current in UHV AC Live Working

Equipotential entry on ultrahigh voltage alternating current (UHV AC) transmission lines produces brief potential transfer current pulses with high amplitude. This study develops a coupled capacitance model that retains phase conductors A, B, and C, human body node M, and tower/ground reference G. Capacitances extracted with a three-dimensional quasi-electrostatic boundary element method (BEM) are incorporated into an electromagnetic transient (EMT) model with a cybernetic arc representation and explicit ignition and extinction logic. Under baseline conditions, the proposed model increased peak current by 2.281–2.985% and total specific energy by 10.189–12.868% relative to the traditional model. Coupling between the human body and the two nonworking phases contributed to the transient current balance at node M. Within the investigated configuration with an ideal source, phase-to-ground and phase-to-phase branch currents remained small relative to the peak transfer current. The calculated peak current and total specific energy were compared with reported 1000 kV tension tower measurements. Across the ranges examined in the sensitivity analysis, the values from the proposed model remained higher than the values from the traditional model, and total specific energy was most sensitive to the breakdown threshold and initial gap.