Variable Frequency Series Resonant Test System

Introduction to the Tuning-Type Variable Frequency Series Resonant Voltage Withstand Device

The tuning-mode variable frequency series resonance voltage-withstanding device primarily targets11kV/30MWDesign and manufacturing of AC withstand voltage test for hydro-generator. Reactors are designed with two separate units.

The Variable Frequency Series Resonant Voltage-withstanding Device consists mainly of a variable frequency control power supply, excitation transformer, reactor, and capacitor voltage divider.

The advantages of the tuning-type variable frequency series resonance voltage withstand device in power system applications:

1The required power capacity is significantly reduced. Series resonant power supplies utilize resonant inductors and the tested capacitance to generate high voltage and high current. Throughout the system, the power supply only needs to provide the active power consumption of the system, thus, the power required for the test is only a fraction of the test capacity.1/Q。

2The weight and volume of the equipment have been significantly reduced. In series resonance power supplies, not only are the bulky high-power voltage regulators and the common high-power power frequency test transformers eliminated, but the resonant excitation power supply also only requires a test capacity of1/QReducing system weight and volume significantly, typically by about one-third compared to standard testing equipment.1/10-1/30。

3Enhanced output voltage waveform quality. The resonant power supply, a resonant filter circuit, improves the waveform distortion of the output voltage, achieving a high-quality sine wave. It effectively prevents false breakdown of the sample due to harmonic peak values.

4Prevent large short-circuit currents from burning fault points. In series resonance, when the insulation weakness of the test item is punctured, the circuit immediately detunes, and the loop current rapidly drops to the normal test current level.1/QWhen performing dielectric withstand tests using parallel resonance or test transformer methods, the breakdown current immediately rises several tens of times. Compared to these methods, the difference between the short-circuit current and the breakdown current is several hundred times. Therefore, series resonance can effectively locate insulation weaknesses without the risk of large short-circuit current causing burnout at fault points.

5No voltage recovery will occur. When the sample is punctured, the high voltage will immediately disappear due to the loss of resonance conditions, and the arc will extinguish immediately. The process of re-establishing the recovery voltage is lengthy, making it easy to disconnect the power supply before reaching the flashover voltage again. This voltage recovery process is an intermittent oscillation of energy accumulation, which is long and does not involve any over-voltage recovery.