Research on Closing-loop Current Calculation Method and Control Strategy in Complex Distribution Network

Closing-loop operation can improve the reliability of distribution network, but the closing-loop current may impact the stability of operation. In order to improve the success rate of closing-loop operation, this paper proposes a precise calculation method of closing-loop current in complex distribution network. The current calculation method takes shunting effect of the branches, sympathetic inrush current and transient characteristics of distributed generation (DG) into account. When the value of closing-loop current is too large, it is necessary to regulate the distribution network to complete the closing-loop operation. Closing-loop current, voltage deviation and active power loss are taken as the objective functions in this paper, then transformer ratio, reactive power compensation of static var compensator (SVC) and reactive power output of DG are taken as the regulation means to establish a comprehensive regulation model of closing-loop operation. The model is solved by improved multi-objective particle swarm optimization (IMOPSO) to obtain the control strategy. The proposed method is applied to the case of Shanghai Lingang distribution network. The results show that the calculation method can calculate the closing-loop current precisely, and the regulating strategy can assist operators to complete the closing-loop operation safely.