In this paper

the application of automatic voltage control（AVC）in large-scale nuclear power plant is introduced. The working principle of AVC in power plant is described in detail from such aspects as system principle

system structure

reactive power distribution principle

substation adjustment strategy and logic locking etc. According to the special situation of large nuclear power plant

the problems of AVC in the actual operation process are analyzed. In view of the issue of matching the AVC with the automatic excitation regulator（AVR）

the measures to modify the AVC setting have been taken as for the problem of non-triggering alarm due to abnormal bus bar voltage and of the lack of data lock without refresh in the background control logic

the measures on adding related control logic in AVC background are adopted. In view of such issue as frequently triggering DCS magnetic latching alarm

the measures to modify the DCS logic are proposed. Both reliability and stability of AVC system are improved through the summarization of AVC application and and solution to the existed problems

which provide assurance for safe and stable operation of power system and

at the same time

provide valuable operation experience for the same type of nuclear power plant.