Identification of weak links in urban distribution networks based on probabilistic currents

The voltage quality of power supply to residential customers of 10 kV and below urban distribution networks and line overload situation are affected by the comprehensive influence of substation 10kV bus voltage, and each distribution transformer load, etc. In space and time, the characteristics of random change, especially in the case of 10kV bus voltage, network structure, and parameters determined, the random fluctuation of each distribution substation load, which directly leads to random fluctuations in distribution line current and distribution substation voltage. In this paper, the random fluctuation model of distribution substation load is derived by combining the voltage qualification rate and the definition of line overload with the long-time statistical analysis of each distribution substation load in the actual distribution network. The probabilistic trend considering the correlation of random fluctuation is used to calculate the probability of the load ratio of 10kV line and the outlet voltage amplitude of all distribution transformers on the line to analyze the overall power supply voltage qualification rate of the 10kV line and to explore the weak links of the urban distribution network. The research example shows that the probabilistic trend calculation can be used to analyze and evaluate the line load rate and the supply voltage qualification rate in a more comprehensive way, which provides a theoretical basis for rationally improving the urban distribution network, improving the supply voltage qualification rate and reducing the line load rate.