An ultra-high voltage(UHV)half-wavelength alternating current(AC)power transmission line connected to the original direct current(DC)asynchronous networking system is built based on the quasi-steady model of UHV half-wavelength. A combined reactive power control scheme is proposed for half-wavelength transmission system with different power supply of half-wavelength and DC power by means of the DC link filter and the power supply terminal reactive power compensation device. In order to improve the power factor at the end of the half-wavelength transmission system

which is based on the voltage and reactive power characteristics of the half-wavelength transmission line on both sides of the half-wavelength transmission line. The steady-state operation characteristics of the system including voltage and current distribution characteristics of the half-wavelength transmission line under different power supply and load power factors are analyzed

as is the influence of the variation of DC operating power on the voltage of the half-wavelength transmission system.