Estimation of the minimum level of higher harmonics in the single-phase-to-ground fault current in compensated 6–10 kV networks

Purpose Development of a model for a compensated 6–10 kV network and a methodology for selecting its element parameters based on estimating the minimum level of higher harmonics in the single-phase-to-ground fault current. Methodology. To estimate the minimum level of higher harmonics in single-phase-to-ground fault current currents, a generalized model of a compensated 6–10 kV cable network and its constituent elements, implemented in the Matlab system with the Simulink extension package, was used. The generalized model of the compensated 6–10 kV cable network and its element parameters were obtained based on a statistical analysis of data from the power supply systems of cities and industrial enterprises. Findings. The main requirements for the equivalent calculation scheme of a 6–10 kV cable network for estimating the minimum level of higher harmonics in the single-phase-to-ground fault current were formulated, and the ranges of variation and average values of its parameters were determined. The developed mathematical model of the 6–10 kV cable network accounts for the main factors determining the minimum level of higher harmonics in the single-phase-to-ground fault current. Based on the results of computational experiments performed on the mathematical models of 6–10 kV cable networks, it was established that to ensure the required sensitivity, single-phase-to-ground fault protection devices based on the use of higher harmonics must have a primary pickup current of no more than 0.1A. Originality.  A model of a compensated 6–10 kV network was developed, which allows clarifying the sensitivity requirements for single-phase-to-ground fault protection systems based on the use of higher harmonics, thereby enhancing their operational efficiency. Practical value. Based on the mathematical model, a methodology for selecting its element parameters is proposed, which utilizes the estimation of the minimum level of higher harmonics in the single-phase-to-ground fault currents.