Modelling of changes in the internal insulation parameters of high-voltage bushing to analyze the reliability of control under operating voltage

Abstract

The article considers the modelling of changes in the parameters of the internal insulation of high-voltage bushings for the analysis of the reliability of control under operating voltage. The data of the actually installed input at the substation were used to model the parameters of the internal insulation of the high-voltage input. To assess the relationship between the dielectric losses of the capacitor-type input insulation and its condition, a substitution scheme was used, in which the active power is equal to the power dissipated in the input insulation, and the current is shifted relative to the voltage by the same angle as in this input. The modelled parameters are the capacity of the internal insulation of the input, the active resistance of the input and the resistance that simulates a change in the parameters of the internal insulation. The numerical value of the capacitive current through the insulation of the high-voltage input, the numerical value of the active current, the numerical value of the resistance, and the numerical value of the power loss for this input are calculated. A simplified high-voltage input insulation scheme has been developed. Losses were calculated and evaluated when the tangent of the dielectric loss angle was changed by 2%. The replacement scheme for isolating the high-voltage input without taking into account the possibility of changing the parameters is given. A model was built that allows you to take into account the change in input parameters, to which an additional resistance is connected in parallel. A resistive divider circuit was chosen as the circuit simulating the parameters because it provides sufficient accuracy, stability, and power. The method that was used to simulate the change in the parameters of the internal insulation of the capacitor-type high-voltage inputs can be recommended as an aid to the analysis of the sensitivity of the control device under the operating voltage of the inputs of power transformers.