ДОСЛІДЖЕННЯ ВПЛИВУ ІМПУЛЬСНИХ ПРОЦЕСІВ В ОБМОТКАХ ТРАНСФОРМАТОРА

Abstract

The article examines the existence of uneven voltage distribution under the action of transient voltage, which is the main cause of insulation breakdown of power transformers. In fact, the winding of the power transformer has no tap and cannot be directly used to measure the impulse voltage. The study of pulse voltage distribution measurement is important and practical in engineering. The voltage distribution for the isolated neutral, when the current does not flow through the winding ipr = 0, occurs according to the exponential dependence, and the amount of overvoltage is equal to the initial voltage on the winding of the transformer, which decreases. When the induced voltage is varied along the winding of a transformer with an isolated neutral in steady state, the entire winding takes the same potential with respect to ground and the steady voltage is a straight line. It follows that in the case of an insulated neutral, the end of the winding must have the same insulation as the beginning. The change in maximum voltage is presented when U0 changes in the range from 550 kV to 850 kV. In the work, the change of U0 from values (550-850 kV) to 0 V was studied, with the length of the coil wire x=l= 100 m. Thus, in both cases, it is not difficult to determine the sum of the amplitudes of individual harmonics at any point of the winding. During the development of self-oscillations, the voltage exceeds the set value, and tends to decrease the frequency of self-oscillations. On the basis of the conducted research, transient overvoltage distributions in the transformer windings were calculated. These results will be useful for designers to evaluate the resistance of transformer insulation to transient voltages and further optimize the graded longitudinal insulation. Transient overvoltage distributions in transformer windings are modeled. It was concluded that the impulse voltage distributions in the transformer windings are mainly related to the high-frequency components of the winding voltage.