In recent years, with the rapid development of the national economy, the power grid load has been increasing; at the same time, the number of impulsive and nonlinear loads in the power grid has also increased, resulting in increasingly poor power quality. To ensure the safe operation of the power grid, local power grid companies generally mandate that large nonlinear power consumers add power quality management equipment. Currently, the main power quality management equipment includes FC, APF, SVC, and SVG. Due to its advantages such as good inductive linearity, low noise, and oil-free operation, air-core reactors are widely used in power quality management equipment.

With the increasing use of air-core reactors, quality accidents involving them also occur frequently. In the majority of these accidents, reactor burnout is caused by inter-turn insulation breakdown. Besides issues with the manufacturing process, lightning strikes also contribute significantly to this problem.

By studying the voltage initial distribution, steady-state distribution, and voltage distribution during the oscillation process of air-core reactor windings, the amplitude and location of overvoltages can be determined in order to find appropriate protection measures.

Voltage Effect Analysis

Under power frequency voltage, the impedance exhibited by stray capacitors is much greater than the inductive reactance and resistance of the windings. In this case, inductance plays a dominant role, and capacitance can be ignored. However, under the influence of a shock wave, because the wavefront transition is infinitely short, it is equivalent to an instantaneous infinite frequency. In this case, the inductive reactance in the equivalent circuit will greatly exceed the inductive reactance of the corresponding stray capacitors. Therefore, the equivalent circuit diagram can be simplified to an open-circuit state where reactance and resistance are equivalent to the circuit.

The tail of a radio wave changes relatively slowly; a right-angled wave that reaches a stable value is actually a direct current voltage, at which point the resistance of the zombie winding plays a dominant role.

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