Calculation method of closed-loop current in distribution network based on the improved cumulant method

The closing interconnection switch for power supply operation can improve the reliability of the distribution network, but the closing loop blindly is harmful. At the same time, the access of distributed generation(DG) brings uncertainty to the closing loop of distribution network, which needs to be solved by probabilistic load flow calculation method. Therefore, this paper proposes a closed-loop current calculation method of distribution network based on the improved cumulant method. Firstly, the probability distribution model of load, wind and solar output is established and the cumulants of each order are calculated, and the closed-loop current calculation equation is established. Then, the wind and solar output range is divided into multiple sections, and the equations are linearized at each reference point, and the calculation error is reduced by improving cumulant method. Based on the closed-loop current cumulants and the series expansion method, the cumulative probability distribution characteristics of the closed-loop current are obtained. Finally, the IEEE 33 node system with DG is simulated. The results show that the proposed method can effectively calculate the closed-loop current of the first branch of the feeder, and the calculation time is significantly shortened compared with the Monte Carlo Simulation Method.