Impulse Voltage Distribution of High Voltage Transformer

Abstract

Power transformers are one of the most expensive and essential parts of the electrical power system. Many causes affect the transformer and the most common is impulse voltage. The impulse voltage arises from the lightning and sudden switching in the system. So, it becomes very essential to have a proper analysis of the impulse voltage behavior in the transformer. For the analysis of the impact of impulse voltage, the voltage stresses generating in the various parts of the transformer as well as the capacitance formation between transformer winding and earthed parts, within each winding, between discs, turns, and layers, and between individual coils have to be calculated by preparing its mathematical model. After calculating the capacitance generated in the transformer, the voltages at each node i.e. between disc with time is measured via simulations. The value of calculated capacitance and the simulated voltage at each node over time is compared with the software for analyzing the better result. The value of the simulated voltage at each node is important to decide the insulation strength required at each node for the safe operation of the transformer. For an industry, accuracy in the calculation, as well as the time cycle reduction in manufacturing and testing through the software is very important aspects. For that reason, the automatic entry of the data with precise calculation is required. This aim will be accomplished by coding in the visual basic of application excel. The required winding arrangement data is fetched from the thermal analysis of the software. Therefore, for an initial stage of the project, analysis of the thermal analysis software is mandatory.