Abstract: The current transformer is a key device for the stable operation of SVG, serving as the "eye" of the SVG system by monitoring the control point current. The accuracy of its sampling affects the operational safety and reliability of the SVG system. Polarity errors in the current transformer can lead to uncontrolled full output of the SVG in constant power factor and constant reactive power modes, differential protection actions, and incorrect sampling display. This paper, through principle analysis and on-site practical operations, summarizes a method for determining the polarity of the SVG incoming line current transformer based on the phase of device current sampling in a new energy power station. Using this method, it is possible to quickly determine whether there is a polarity error in the current transformer during the initial stage of SVG commissioning. This can provide a scientific basis for on-site SVG inspections.