The simulation model of a 6 kV open-cast distribution network with an isolated neutral is presented. This model was developed for studying various methods of determining the parameters of network phase isolation relative to the ground. The model was built in the MATLAB software using the Simulink package and the SimPowerSystems library. Its adequacy was verified by the single-phase-to-ground fault current. The results obtained in the process of simulation and analytical calculation had a slight discrepancy, which allows to consider the simulation model as adequate.
The analysis of the current methods for determining the insulation parameters showed that the most convenient and safe approach is based on connecting additional capacitance between one of the phases of the network and the ground. This method not only ensures safety when performing measurements, but also eliminates a decrease in the reliability of electrical distribution networks. When studying the insulation parameters in the normal operating mode, the measurements are made without removing the operating voltage. Among other things, the additional capacitance has stable parameters that do not change (in contrast to the additional active conductivity) as the measurements are performed.
The results of studies are given related to the influence of various factors on the accuracy of measuring the active and reactive components of the total insulation resistance of the network phases relative to the ground by the indicated method. The errors of the considered method based on connecting additional capacitance between one of the phases of the network and the ground are analyzed. It is concluded that the load in the network has little effect on the accuracy of the results. At the same time, the presence of asymmetry in the network leads to a significant error. The way to eliminate this disadvantage is proposed.