Method for discriminating magneting inrush current of direct current transmission converter transformer
A technology for converting transformers and exciting inrush currents, applied in the directions of measuring current/voltage, measuring electrical variables, instruments, etc., which can solve problems such as high inrush current symmetry, malfunction, and low second harmonic content of differential current
Inactive Publication Date: 2013-07-03
TSINGHUA UNIV
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[0003] If the residual magnetism polarity of the two converter transformers is different due to the factory test, when the converter transformer is charged for the first time, the phase difference of the excitation inrush current generated in the two converter transformers will be very large, resulting in the synthesis of The symmetry of the inrush current is very high, similar to a sine wave, resulting in a low second harmonic content of the differential current, and the harmonic braking criterion cannot effectively brake the differential protection, resulting in malfunctions
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[0038] The preferred embodiments will be described in detail below in conjunction with the accompanying drawings. It should be emphasized that the following description is only exemplary and not intended to limit the scope of the invention and its application.
[0039] figure 1 DC transmission converter transformer wiring diagram. The transformers T1 and T2 contain residual magnetism in different directions. At a certain moment, T1 and T2 are switched on without load, and an initial excitation inrush current will be generated in the converter transformer, which is a synthetic current on the system side.
[0040] figure 2 is the phase current of the converter transformer T1 in the embodiment of the present invention. It can be seen from the figure that the three phases of the converter transformer all have excitation inrush currents, and the A phase inrush current is relatively large.
[0041] image 3 is the phase current of the converter transformer T2 in the embodimen...
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The invention discloses a method for discriminating a magneting inrush current of a direct current transmission converter transformer in the technical field of main equipment relay protection of an electric system. In the method, the magneting inrush current of the converter transformer, in particular a symmetric magneting inrush current generated at a system side while the converter transformer is charged for the first time, is discriminated by means of a waveform coefficient of a converter transformer phase current. Compared with a secondary harmonic ratio magneting inrush current locking criterion, the method has the characteristic of high reliability in an aspect of identifying the magneting inrush current, in particular the symmetric magneting inrush current at the system side, and in an aspect of discriminating small turn-to-turn short circuit situations.
Description
technical field [0001] The invention belongs to the technical field of relay protection for main equipment in a power system, and in particular relates to a method for identifying the excitation inrush current of a direct current transmission converter transformer. Background technique [0002] In bipolar DC transmission, usually Y N Y and Y N The converter transformer connected to D11, the converter transformer is one of the most important electrical equipment in the DC transmission system. In order to protect the converter transformer, many protections are used. For each converter transformer, the differential protection is used as the main protection, and it is equipped with the second harmonic braking criterion. The sub-harmonic criterion prevents the misoperation of the large difference protection. [0003] If the residual magnetism polarity of the two converter transformers is different due to the factory test, when the converter transformer is charged for the first...
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IPC IPC(8): G01R19/165
Inventor 毕大强冯存亮
Owner TSINGHUA UNIV