On-line loop closing power transforming operation safety discrimination method and system

Provided are an on-line loop closing power transforming operation safety discrimination method and a system. A topological network structure, element parameters and operation parameters are obtained, and loop parameters of a path of a loop to be closed are obtained according to the topological network structure, the element parameters and the operation parameters; a selected time domain is obtained and the time domain type is determined; if the time domain type is a real-time state, a forward-backward sweep method and a state estimation method is employed to determine voltage phase angles or voltage phase angles or voltage amplitudes of buses at two sides of a loop closing feed line and a voltage phase angle difference and a voltage amplitude difference are determined; the loop closing stable state current is determined according to the voltage phase angle difference and the voltage amplitude difference; feasibility of the loop closing power transforming operation is determined. The method and the system determine a voltage phase angle difference and a voltage amplitude difference of buses at two sides of a loop closing feed line according to selection of the time domain and loop parameters of a path of a loop to be closed, further determines a loop stable state current, and then determines feasibility of the loop closing power transforming operation. The reliability is high, and the success rate of loop closing power transforming operation and power supply reliability can be ensured to a certain degree.