Experiment design and analysis method for most severe current stress born by thyristor used for converter valve

Abstract

The invention discloses an experiment design and analysis method for a most severe current stress born by a thyristor used for a converter valve. In a working condition that a current of the converter valve is switched on, a switch-on current stress of the thyristor under non-periodic trigger is the most severe. In order to verify that the thyristor used for the converter valve can bear the switch-on stress, a special experiment is designed in the invention, wherein a surge capacitor, a saturable reactor and the thyristor are connected in series; the surge capacitor generates a discharge current which flows through the thyristor in the form of discharge; and experiment parameters are designed to ensure that a current stress applied to the thyristor is equivalent to the current stress of the converter valve in the working condition of non-periodic trigger. The experiment designed in the invention is simple to realize and easy to adjust and has high equivalence.

Description

technical field [0001] The invention relates to the field of power system devices, in particular to an experiment design and analysis method for thyristors used in converter valves to withstand the most severe current stress. Background technique [0002] Thyristors for DC transmission converter valves are the most critical and core devices in converter valves. During the operation of the converter valve, the voltage and current stresses on the thyristor need to be within its safe operating range to ensure the normal operation of the thyristor. Among the current stresses that the thyristors should be able to withstand, the most severe transient current stress is the current caused by the transfer of the energy of the arrester and the energy of the stray capacitance between the valve terminals through the thyristor when the converter valve is triggered acyclically (according to IEC and GB). stress. [0003] Generally, the bridge arm of the converter valve is composed of doz...

AI Technical Summary

Problems solved by technology

For different converter valve projects, the most severe current stress that the thyristor should be able to withstand is different, so there are many disadvantages in the existing test

[0004] In the national standard "GB / T20992-2007" thyristor performance parameters, the parameters about the turn-on current withstand characteristics are only the critical rise rate of the on-state current, the critical rise rate of the non-repetitive on-state current, and the test conditions of these two parameters, but during the turn-on of the thyristor , the current flowing through the thyristor is a time-varying curve, and the current limit value of the thyristor at the initial stage of turning on cannot be fully revealed only by the current change rate and test conditions, and the most severe current stress that the thyristor bears in the converter valve also varies with time. Intensity curves over time

The national standard "GB / T20992-2007" adopts a composite method when describing the test waveform of the thyristor turn-on current stress, and generates the current intensity waveform that the thyristor should withstand in stages and finally integrates it. The current waveform that should be endured in the working condition does not match, so there is a risk that the thyristor is too harsh and does not meet the requirements in accordance with the national standard test method

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