Distribution Network Sag Assessment under Stochastic Faults Based on Network Transformation and Fitting Integral

In this paper, according to the structure and load characteristics of the distribution network, a network transformation algorithm is proposed. The simplified analysis circuit with the root node of the distribution network as the observation port is obtained by a series-parallel transformation method, and then the network state is solved. The fitting method is used to obtain the relationship between the voltage of each node and the fault location, and weighted integral is used to evaluate the expected value of voltage sag probability of all nodes and the whole distribution network system. Taking The typical systems of IEEE 33-bus as the simulation object, the results show that the error between the integral fitting algorithm and the Monte Carlo stochastic algorithm is within the allowable range, and the former greatly improves the calculation speed.