Partial discharge test method with variable frequency resonant voltage using intermittent excitation

Abstract

The invention discloses a method for testing partial discharge with variable frequency resonance with intermittent excitation, and relates to AC withstand voltage and partial discharge tests of electric equipment. During the test, the frequency conversion resonant withstand voltage test device is connected to the tested product to form an AC withstand voltage and partial discharge test system. Through the excitation mode of the intermittent output of the variable frequency power supply, the test system can perform partial discharge detection of the tested product while the AC withstand voltage is used. It is not affected by the clutter interference of the power supply line and the burr of the variable frequency power switch. The test voltage will inevitably drop during the intermittent period of excitation, and the amplitude fluctuation range can be controlled by adjusting the intermittent cycle number of the output voltage of the variable frequency power supply, and finally meet the requirements of the AC withstand voltage test procedure for the test voltage deviation. For power cables, in this AC withstand voltage test mode in which the cycles of constant amplitude oscillation-decreasing oscillation-increasing oscillation appear alternately, not only the influence of power supply interference on partial discharge measurement can be avoided, but also partial discharge of traditional damped oscillatory wave cables can be avoided. Test the possibility of missed detection due to DC boost (not actual working conditions).

Description

technical field [0001] The invention relates to the measurement test of AC withstand voltage and partial discharge (hereinafter referred to as partial discharge) of electric equipment, in particular to a test method of variable frequency resonance withstand voltage partial discharge using intermittent excitation. Background technique [0002] Before the power line is put into operation or after overhaul, the insulation state of the power components or equipment must be inspected and evaluated, and AC withstand voltage is the most basic test item. The new national electric power test regulations require that high-voltage cables (66kV and above) should be subjected to partial discharge measurement at the same time as AC withstand voltage, in order to more comprehensively evaluate the cable insulation state. In the past, the partial discharge can be measured synchronously when using the frequency conversion resonant withstand voltage test device for AC withstand voltage, but of...

AI Technical Summary

Problems solved by technology

In the past, the partial discharge can be measured synchronously when using the frequency conversion resonant withstand voltage test device for AC withstand voltage, but often due to the interference of the frequency conversion power supply itself and the power supply line, the observation and detection sensitivity of the partial discharge signal of the test system are affected, and the measurement effect is not good. Good, sometimes the partial discharge signal is even submerged by these interference signals, and cannot be observed at all

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