SVG (static var generator) control strategy for changing characteristics along with state of power grid

The invention discloses an SVG (Static Var Generator) control strategy capable of changing characteristics along with the state of a power grid, which comprises the following steps: when the power grid operates in a steady state, the SVG operates in a fixed reactive power control mode and the power grid breaks down, the SVG selects whether to lock according to the voltage of a control point, if the SVG is switched to the locking mode, when the power grid fault is eliminated and the amplitude is recovered to a low-voltage unlocking value ULset2, the SVG is unlocked after a delay time period Tset, and the SVG operates in a constant reactive power control mode; a control strategy of the SVG is switched to a transient stage constant voltage control mode; and when the amplitude and the reactive power output Q of the SVG meet a preset condition, the control strategy of the SVG is switched from the constant voltage control mode of the transient stage to the constant reactive power control strategy of the steady stat