Thyristor synchronization signal processing method applicable to changing frequency

Abstract

The invention belongs to the field of high-power converting technology control, and specifically relates to a thyristor synchronization signal processing method applicable to changing frequency. The method comprises the following steps: filtering out the high-frequency component of an original synchronization signal through a first-order RC low-pass filter; converting the filtered synchronization signal into a square wave signal and inputting the square wave signal into a digital signal processor (DSP), and using a capture unit of the DSP to judge the frequency of the square wave signal; calculating the phase shift produced at the frequency based on the phase frequency characteristics of the filter; and predicting the zero-crossing point of a next-cycle synchronization signal based on the zero-crossing point of the square wave signal and the phase shift produced after filtering, and outputting a square wave signal of the same phase as the original synchronization signal to perform subsequent trigger pulse processing. The method has the advantages of accuracy, quickness, strong frequency tracking ability, and capability of improving the trigger precision of thyristor converters.

Description

technical field [0001] The invention belongs to the field of high-power variable current technology control, and specifically relates to a method for accurately judging the zero-crossing point of a variable frequency signal in a harsh signal environment. The method can also be applied to other variable frequency signal processing fields. Background technique [0002] The HL-2A device is a controlled nuclear fusion experimental device. The poloidal field coil power supply of the device is powered by a 125MVA AC pulse generator set. To send a trigger pulse for the thyristor at all times, that is, it is necessary to accurately judge the zero-crossing point of the voltage synchronization signal on the AC side. However, the loads carried by the 125MVA generator set are all high-power variable current loads, and the voltage waveform on the AC side is severely distorted. Using the synchronization signal directly may cause misjudgment. The output voltage waveform of the generator un...

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Problems solved by technology

However, the loads carried by the 125MVA generator set are all high-power variable current loads, and the voltage waveform on the AC side is severely distorted. Using the synchronization signal directly may cause misjudgment. The output voltage waveform of the generator under load is as follows: figure 1 As shown, many fluctuations that will affect the judgment of zero crossing can be seen on the waveform

What's more special is that the output frequency of the generator gradually decreases with the discharge of the device (it can be reduced from 100Hz to 80Hz within 5 seconds), which increases the difficulty of accurately judging the zero-crossing point of the synchronous signal

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