The discrete reactive devices in automatic volume control(AVC)need to judge whether its action will lead to bus voltage off-limit. Aiming at the shortcomings of the traditional non-topological and topological methods

a new non-topological precheck method based on two fundamental assumptions is proposed. Firstly

a nonlinear model of bus voltage variation is derived

and then simplified into a linear model. It is proved that the current standard recommendation method is a special case of the linear model. Because of the imprecision and impracticality caused by system impedance

while considering the actual operating characteristics of power

a recursive estimation method combined with a Kalman filter is proposed using only the most recent action of discrete reactive device information. Finally

the validity of the method is verified through the dispatcher flow simulation and field data.