Novel thyristor overvoltage protection method

Abstract

The invention provides a novel thyristor overvoltage protection method, which comprises the steps of: measuring the voltage of the thyristor by a thyristor triggering and monitoring unit by utilizing a voltage divider, and immediately triggering the thyristor when the voltage of the thyristor reaches a protection level. A direct current voltage-sharing resistor of the thyristor is skillfully used as a high-voltage arm of the voltage divider, and a low-voltage arm is arranged on the thyristor triggering and monitoring unit. The thyristor overvoltage protection level can be adjusted in real time as required. The method overcomes all the defects of the method in which a BOD (Break Over Diode) device is used for overvoltage protection.

Description

technical field [0001] The invention belongs to the fields of electronic power and direct current transmission, and relates to a thyristor overvoltage protection method. Background technique [0002] The traditional thyristor overvoltage protection method is to immediately protect and trigger the thyristor when the voltage of the thyristor reaches a preset protection level, and the protection level is a preset fixed value. However, in the high-voltage and high-power field, thyristors usually operate in series. Damping resistors, damping capacitors, and DC equalizing resistors are connected in parallel at both ends of the thyristors. The normal triggering and overvoltage protection of the thyristors are realized by the thyristor triggering and monitoring unit. , when the equipment continues to operate, the thyristor connected in series with it can be normally triggered and turned on, and the thyristor whose normal trigger circuit is damaged can only be triggered by overvoltag...

AI Technical Summary

Problems solved by technology

The BOD device and the current limiting resistor are installed in the thyristor triggering and monitoring unit. The thyristor overvoltage protection implemented in this way has four disadvantages. Disadvantage 1: The high voltage of the anode of the thyristor is introduced into the thyristor triggering and monitoring unit, which makes the circuit board very large , which is not conducive to the miniaturization and compactness of the equipment; Disadvantage 2: When the BOD protection operates, the instantaneous high voltage and large current (pulse current) of the BOD circuit have greater electromagnetic interference on the logic circuit of the thyristor trigger and monitoring unit, which reduces the thyristor trigger. The ability to resist electromagnetic interference with the monitoring unit; Disadvantage 3: BOD devices are more expensive, which increases the cost of equipment; Disadvantage 4: The level of overvoltage protection is not adjustable, and the protection level is the breakdown voltage of BOD devices

[0006] The above two patent applications adopt BOD protection. The BOD device and the current-limiting resistor are installed in the thyristor triggering and monitoring unit. There are four shortcomings in the thyristor overvoltage protection realized in this way. Disadvantage 1: The high voltage of the anode of the thyristor is introduced into the thyristor triggering and monitoring unit, which makes the size of the circuit board large, which is not conducive to the miniaturization and compactness of the equipment; the second disadvantage: when the BOD protection operates, the instantaneous high voltage and large current (pulse current) of the BOD circuit have a greater impact on the logic circuit of the thyristor trigger and monitoring unit. Large electromagnetic interference reduces the anti-electromagnetic interference ability of the thyristor trigger and monitoring unit; Disadvantage 3: BOD devices are more expensive, which increases the cost of equipment; Disadvantage 4: The overvoltage protection level is not adjustable, and the protection level is the breakdown voltage of the BOD device

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