A Leakage Current Calculation Method for Thyristor Out-of-Band Circuits for Voltage Resistance Test

Abstract

The invention discloses a leakage current calculation method for carrying out a voltage-resistant performance test of the out-of-band circuit of a thyristor. The leakage current calculation method comprises the steps of: reading the damping capacitance value C and the voltage-equalizing resistance value R<DC> of the damping loop of the thyristor; reading the thyristor voltage sampling data U(t)for carrying out the voltage-resistant performance test of the out-of-band circuit of the thyristor; smoothing the U(t), so that the smoothed waveform U<s>(t) is obtained; intercepting 20 ms U<s>(t)data in one cycle; calculating the maximum value U<max> and the minimum value U<min> of the intercepted U<s>(t) data and the time difference t when the maximum value and the minimum value appear; calculating the damping capacitance discharge current I<cb> by utilizing the U<max>, the U<min>, the t and the C; and then, obtaining the leakage current I by calculation through the I<cb>. According to the leakage current calculation method in the invention, according to the damping capacitance and voltage-equalizing resistance parameters, the leakage current of the thyristor is calculated byutilization of the sampling data of the thyristor voltage; on one hand, increasing of a current measuring point in the voltage-resistant performance test of the thyristor is avoided; and, on the otherhand, the thyristor voltage-resistant performance test of the out-of-band circuit becomes possible.

Description

technical field [0001] The invention relates to a thyristor detection technology, in particular to a leakage current calculation method for testing the voltage resistance performance of a thyristor out-of-band circuit for direct current transmission. Background technique [0002] The thyristor converter valve is the core equipment of the DC transmission project, which can convert the three-phase AC voltage into DC voltage. Such as figure 2 As shown, the thyristor converter valve is generally composed of 6 single valves, each single valve contains 6 valve sections, and one valve section contains 13 thyristors, so a thyristor converter valve is composed of 468 thyristors and related components. For DC power transmission projects, ±500kV DC power transmission projects need 8 thyristor converter valves, and ±800kV DC power transmission projects need 16 thyristor converter valves, a total of 3744 and 7488 thyristors, so the number of thyristors contained in DC power transmission...

AI Technical Summary

Problems solved by technology

[0004] At present, when carrying out the withstand voltage performance test of the thyristor, the staff at the DC transmission site need to untie the external circuit of the thyristor (damping circuit and voltage equalizing resistor). The elastic terminals or screws of the unsafe terminals are also likely to cause undesired consequences such as loose screws, wrong circuit connections, and equipment damage, which will affect the stability of DC operation.

However, when the out-of-band circuit is used to test the withstand voltage performance of the thyristor, the damping circuit will also flow leakage current, and because the thyristor is fastened in the frame, the current flowing through the thyristor cannot be directly measured, and only the current flowing through the thyristor can be detected during the detection process. The current of the voltage generating device, that is, the sum of the leakage current of the gate and the leakage current of the external circuit, makes it difficult to judge the withstand voltage performance of the gate

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