| Today, the power supply enterprise tries to offer good long-term customer service. And the customer requests higher power supply reliability at the same time. As the 10kV level distribution network has formed closed-loop structure, it is possible to observably improve the supply reliability by loop closing operation. However, at present, there is few research about loop closing operation of distribution network. And the operator just makes the decision by experience, which reduces the supply reliability and results in accidents occurrence. If the amplitude and voltage phase of the bus bar is significant different before loop closed, the loop current will be large and the protection will act. The impulse current will destroy the system equipments and impact the power quality of the customer. During the loop closing, the short-circuit faults will more seriously effect the safe and steady operation of the power grid. Then it is necessarily to study and analyze on the security of loop closing operation in Dongguan Power Gird.This paper analyses the 10kV loop closing connections of Dongguan Power Grid. And the loop closing forms are divided into eight kinds. To detailedly analyse the security of the eight kinds of loop closing modes, the loop closing PSD-BPA models and PSCAD/EMTDC models of Dongguang 10kV level distribution network are built. Based on this, this paper calculates the changes of power flow, the impulse current and the short-circuit during the loop closing operation. The loop closing conclusions are given in this paper, too.To verify the loop closing conclusions, explore and master the key technologies in the process of uninterrupted transferring power supply, and so as to make feasible scheme for uninterrupted transferring power supply, two loop closing and transferring power supply experiments have been carried out in Dongguan Power Grid. At last, this paper gives the loop closing conclusions by summarizing the experiment and the calculation conclusions.
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