Application of series resonance in power system

Series resonance is the design and manufacture of AC voltage withstand test for all electrical main equipment such as 10kV, 35kV cables, generators, 110kV and below power main transformers, and busbar switches.

The advantages of series resonance in power systems:

1. The required power supply capacity is greatly reduced. The series resonant power supply utilizes the resonant reactor and the capacitor of the test product to generate high voltage and high current. In the whole system, the power supply only needs to provide part of the active power consumption of the system. Therefore, the power required for the test is only the test capacity. 1/Q.

2. The weight and size of the equipment are greatly reduced. In the series resonant power supply, not only the bulky high power voltage regulation device and the common high-power power frequency test transformer are omitted, but also the resonant excitation power supply needs only 1/Q of the test capacity, which greatly reduces the weight and volume of the system, generally 1/10-1/30 of a normal test device.

3, to improve the output voltage waveform. The resonant power supply is a resonant filter circuit, which can improve the waveform distortion of the output voltage and obtain a good sinusoidal waveform, effectively preventing the false breakdown of harmonic peaks on the test sample.

4, to prevent large short-circuit current burn point of failure. In the series resonance state, when the insulating weak point of the test piece is broken down, the circuit immediately detunes and the loop current rapidly drops to 1/Q of the normal test current. When the parallel resonant or test transformer method is used for the withstand voltage test, the breakdown current immediately rises several tens of times. Compared with the two, the short-circuit current is different from the breakdown current by several hundred times. Therefore, the series resonance can effectively find the weak points of insulation, and there is no big short circuit current to burn the fault point.

5. No recovery overvoltage will occur. When the sample breaks down, because of the loss of resonance conditions, the high voltage immediately disappears, the arc extinguishes instantly, and the re-establishment process of the recovery voltage is very long. It is easy to disconnect the power supply before the flashover voltage is reached again. This voltage recovery The process is a kind of intermittent oscillation process of energy accumulation, and its process is long, and there will not be any recovery overvoltage.