With the Qishao HVDC accessed to the Hunan power grid

and the vigorous development of clean resources such as hydro-power

wind power

photovoltaic and other clean resources

the growth rate of conventional units is slowing down.If the start-up mode of conventional units in the southern Hunan power grid cannot meet the minimum requirement

it is possible to cause the lack of reactive power support of the southern Hunan power grid.In order to improve the voltage stability of the Hunan power grid

this paper firstly introduces the SVC basic operation principle of TCR type

and establishes the calculation model of Hunan power grid in 2018

and then compares the V-Q curves of the substation in the southern Hunan power grid according to whether the SVC of Chenzhou area is running or not.The effect of SVC to improve voltage stability of the Hunan power grid is verified by computer simulation.