Abstract: Due to the intermittence and fluctuation of photovoltaic power generation, the voltage stability of power grid will be affected after large-scale photovoltaic grid connection. In order to solve the problem that the traditional automatic voltage control has a long cycle and cannot respond to voltage fluctuation in time, an automatic voltage control method based on transient tracking of PV inverter terminal voltage is adopted. Through coordinated control of two-level control and one-level control, the coordinated control of steady-state voltage and transient voltage is realized. The second level control is the voltage and reactive power control of the photovoltaic power station, which optimizes the reactive power and voltage target in the station, and sends the target command to the first level controller. The first level controller realizes the voltage target tracking through the feedback control of the inverter output voltage. At the same time, the intelligent control terminal automatically maintains the output voltage to reach the steady-state voltage target value through fast reactive power target calculation and call, so as to realize the fast support of voltage transient disturbance.