Simulation Study on Electromagnetic Transient of Single Circuit ±800 kV DC Transmission Line and Double Circuit of 500kV AC Transmission Lines Erected on Same Tower

Based on concrete operational condition of single circuit ±800 kV DC transmission line and double circuit 500 kV AC transmission lines erected on the same tower,by means of simulating various serious faults occurred in AC and DC transmission systems the detailed electromagnetic transient simulation is performed to research the interaction between AC and DC transmission systems.Considering different positions on the tower where the transmission lines are erected and the lengths of transmission lines,the impacts of such a erection mode,namely single circuit ±800 kV DC transmission line and double circuit 500kV AC transmission lines on the same tower, on overvoltage levels of DC and AC transmission lines as well as the impacts on the secondary arc current and the recovery voltage of AC transmission lines are respectively studied. Simulation results show that such a erection mode of transmission lines slightly affects respective overvoltage levels of UHVDC and EHVAC transmission lines,thus the insulation coordination schemes for separately erected UHVDC transmission line and EHVAC transmission line can be continually utilized.When non-transposed EHVAC transmission line,configured with high voltage reactor at one terminal,is erected on the same tower with UHVDC transmission line,the EHVAC transmission line has to be faced with such a situation that the secondary arc current is difficult to be extinguished,thus it is necessary to consider countermeasure during the design.