Method and system for quick turn-off of bidirectional thyristor

Abstract

The present invention relates to the technical field of power electronics, and provides a method and system for quickly shutting off a bidirectional thyristor. The system includes a three-phase power grid, a bidirectional thyristor, a resistance-inductive load, a three-level converter, a capacitor energy storage unit, and an LC filter unit. As well as the voltage and current sampling unit and the CPU control unit, the positive input terminal of the three-phase grid voltage is connected to one end of the three groups of triacs abc, and the other end of the three groups of bidirectional thyristors abc is connected to the load and the output end of the three-level inverter; the grid voltage , Thyristor current, and inverter output voltage samples are input to the CPU through voltage and current transformers and sampling conditioning circuits, and the phase of the thyristor current is determined through calculation, and the natural shutdown or reverse voltage shutdown is determined according to the phase. The invention adopts the method of combining natural shut-off and reverse voltage shut-off, solves the problem of overcurrent caused by voltage plus and minus in the conventional method due to wrong judgment of current positive and negative, and can realize fast and accurate shut-off of the bidirectional thyristor.

Description

Technical field [0001] The present invention relates to the field of power electronics technology, in particular to a bidirectional thyristor fast shutdown method and system. Background [0002] With the widespread use of power electronic equipment, various sources of interference and pollution are also increasing, and power quality problems will become more and more complex. The power supply company provides users with power energy with voltage amplitude, frequency deviation, voltage imbalance, transient, fluctuation, interruption, undervoltage overvoltage, harmonics and other problems, which will cause interference and damage to the load of power users. The decline in power quality not only affects the normal and safe power supply of the power supply system, but also causes damage to the electrical equipment, and even endangers personal safety and leads to major economic losses when serious. Accordingly, many power quality control devices, such as unified power quality regulat...

AI Technical Summary

Problems solved by technology

The existing method is to turn off the thyristor by judging the current direction of the thyristor and controlling the voltage of the inverter to be applied to the other end of the thyristor to make it withstand back pressure. However, when the current is near the zero crossing point, it is difficult to detect the actual current direction. , at the same time, because of the delay of the inverter action, the voltage direction is easily reversed, which produces the opposite effect, so that a current spike appears on the thyristor

While damaging the thyristor, the effect of fast shutdown cannot be achieved

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