Abstract: Affected by variations in wind speed and solar irradiance, new energy output tends to cause power fluctuations and reactive power imbalance at grid-connected points. Focusing on the constant voltage control of Static Var Generator (SVG), this paper constructs a control structure consisting of an outer voltage loop, an inner current loop, dead zone judgment, reactive power limiting and anti-windup, and designs three typical operating scenarios: steady-state load variation, abrupt power change and short-term voltage sag. The results show that with SVG in operation, the steady-state voltage deviation decreases from 2.6% to 0.7%, the maximum voltage deviation under abrupt power change drops from 5.1% to 2.0%, and the voltage sag recovery time is shortened from 0.46s to 0.18s. Continuous reactive power regulation can effectively improve the voltage response at grid-connected points.