Loop closing examination and analysis on Beijing 10 kV distribution network

The online operation is quite frequent in Beijing 10 kV distribution network in order to ensure the continuous power supply to important consumers and to increase the network reliability. Mal-protection operation or over-current circumstance might occur because of tremendous loop current during the loop closing if there is a voltage difference between the terminals of the switch. The loop closing examination strategies as well as safety precaution methods were introduced and the loop closing equivalent model was established with an example of Shawo Substation. Making a study of transient and steady process in loop closing, the steady-state loop current and the transient rush current were also calculated. Comparing the recorded diagram with the power flow calculation results, key factors affecting the loop closing safety were discussed. Main adjustment measures for loop closing safety are suggested to limit the loop current, which have instruction significance to the network operation.