In response to the issue that sympathetic inrush may occur in adjacent operating transformers during the no-load closing of a transformer

an analytical method for the generation mechanism of sympathetic inrush considering the load of the transformer and countermeasures to prevent maloperation of the protection are put forward. first of all， based on the flux variation model， the expressions for the flux variation of the transformer under load operation at each stage are derived， the principle and characteristics of the sympathetic inrush are systematically expounded， and the factors affecting the sympathetic inrush are extracted. Second， a real-time digital simulation system is used to model the primary system of a substation， successfully reproducing the sympathetic inrush phenomenon. Simulation analysis examines the effects of switching angle， system connection resistance and load on sympathetic inrush， the yielding results are consistent with theoretical analysis. It is proposed that the effect of the sympathetic inrush can be effectively suppressed by closing the breaker at the peak voltage time， strengthening the connection with the system and increasing the load of connected transformers. Finally， corresponding anti-maloperation countermeasures are proposed to address the impact of sympathetic inrush on protection.