In the initial period of power system restoration, because the generator unit regulating ability is limited, the sympathetic inrush current will appear as a result of the saturation when charging no-load transformer. Based on the equivalent circuit of two shunt wound transforms in initial period of power system restoration, the mathematical representation between sympathetic inrush and main operating parameters was deduced. The influence of load power factor, load capacity and the saturation characteristic of transformers on sympathetic inrush current was analyzed. The process of sympathetic inrush was simulated based on the model with actual situation. The analytical conclusions were verified by computer results obtained and useful conclusion and reference were provided for estimating sympathetic inrush current.
