Electromagnetic transient characteristic of 1000kV half-wavelength AC transmission lines

In China, the energy resources is against the productive forces development, the base of energy in the west is about 3000km away from the load centers in the east, so the transmission systems with long distance and large capacity should be established. In this paper, based on the design example of UHV (1000kV) AC transmission system, the Half Wavelength AC Transmission (HWACT) is introduced, and the study of Some electromagnetic transient characteristic of HWACT lines without the presence of intermediate switching stations by two types of 3 phase conductors arrangements are carried out, such as capacitance effect of unloaded line, single-phase-to-ground fault and switching over voltages; the results shows that 1000kV half wavelength AC Transmission is in well condition : The maximum power frequency voltages rising caused by capacitance effect in unloaded line is 1.04 per unit, by single-phase-to-ground fault is 2.19 per unit, the maximum switching over voltage such as closing unloaded line, 3 phases load shedding and single-phase auto-recloser are 1.6 per unit, 2.0 per unit, 1.7 per unit respectively; and these over voltages are under the concerned regulations of our country owing, except for the amplitude of the secondary arc current, which HSGS can reduce but not ideal.