Calculation and Analysis on Steady-State Induced Voltage During Maintenance Operation of Multi Parallel Circuits of EHV/UHVDC/UHVAC Transmission Lines

Erecting multi circuits of AC and DC transmission lines in the same corridor can save the land resources, however there are electrostatic and electromagnetic couplings among multi circuits of AC and DC transmission lines. It is favorable for the safety of maintenance operation of these transmission lines to research the steady-state induction voltage of transmission lines parallelly erected in the corridor. Through the calculation by electromagnetic transient program(EMTP), a computation model of six UHVAC and EHVDC/UHVDC transmission lines parallelly erected in the corridor located in Huzhou, Zhejiang province is established; the influence due to the coupling between UHVAC lines and EHVDC/UHVDC lines are calculated; the amplitudes and distributions of electrostatic induction voltages and electromagnetic induction voltages during the live-line overhaul and power-off maintenance under the combination of different operating modes of UHVAC and EHVDC/UHVDC lines are analyzed. Analysis results show that the influence of the steady-state induction voltage among parallelly erected multi circuits of AC and DC transmission line on the live-line overhaul and power-off maintenance modes and tools specified in current operating instruction can be neglected.