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Method for detecting inrush current distortion of transformer based on Rogowski coil

A technology of Rogowski coil and detection method is applied in the field of transformer inrush current distortion detection based on Rogowski coil, and the field of judging the abnormal cause of the transformer can solve the problems of operation delay, failure to fully reflect the inrush current distortion, and low redundancy, so as to reduce the calculation effect of error

Inactive Publication Date: 2013-04-17
江苏金思源电气有限公司 +1
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

Waveform symmetry can only be applied to even-order harmonic restraint under the condition of symmetrical inrush current, and it will only appear in some specific cases, and when the transformer is over-excited, although the excitation current waveform is symmetrical, it is also Unable to use waveform symmetry method to distinguish excitation inrush current
In short, the current methods only reflect the distortion of the inrush current from a certain aspect of the degree of current distortion, but do not fully reflect the distortion of the inrush current. Therefore, they all have obvious limitations, low redundancy, and are prone to malfunction or action. time delay

Method used

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  • Method for detecting inrush current distortion of transformer based on Rogowski coil
  • Method for detecting inrush current distortion of transformer based on Rogowski coil
  • Method for detecting inrush current distortion of transformer based on Rogowski coil

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Embodiment 1

[0035] The main flow of the Rogowski coil-based transformer inrush distortion detection method in this embodiment is as follows: figure 1 As shown, it is composed of the Rogowski coil measurement link, the analog-to-digital conversion and filtering link, and the distortion calculation output link. The specific steps of each link are as follows:

[0036] 1. A Rogowski coil is used in the measurement section to measure the large current i(t) on the primary side of the transformer to obtain the differential voltage signal u(t);

[0037] 2. Send u(t) to analog-to-digital conversion and filtering (similar to the prior art, there are many mature methods, not to be described in detail) to obtain digital signal u(n)(n=1,..., N; the number of sampling points of one cycle of N);

[0038] 3. According to the judgment criterion of abnormal current in differential protection, judge whether there is abnormal current. If there is abnormal current, enter the calculation link of step 4 below...

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Abstract

The invention relates to a method for detecting inrush current distortion of a transformer based on a Rogowski coil, which belongs to the technical field of relay protection of electric power systems. The method comprises the following steps of: measuring primary side current of the transformer to acquire a differential voltage analog signal; acquiring a corresponding differential voltage digitalsignal; judging whether abnormal current occurs or not; performing cosine window-added Fourier transform on the differential voltage digital signal to solve effective values of every-time harmonic waves; calculating the degree of distortion, namely judging whether inrush current occurs or not according to the degree of distortion, and the like. By the method, the conditions that incorrect tripping of differential protection during on-load switch-on of the transformer is prevented and exciting current and fault current are strictly distinguished are ensured, a criterion value has extremely high redundancy, and the degree of distortion is accurately and reliably determined.

Description

technical field [0001] The invention relates to a method for discriminating abnormal causes of transformers, in particular to a Rogowski coil-based method for detecting inrush current distortion of transformers, which belongs to the technical field of relay protection for power systems. Background technique [0002] The Rogowski coil is a kind of wire that is evenly wound on a non-magnetic material frame with a uniform cross-section, so that the wire with a large current passes through the center of the coil vertically, and is induced by the change of the magnetic flux generated by the current-carrying conductor under test. A measuring device that produces a voltage signal that can respond to the magnitude of the measured current. The voltage signal induced by the secondary side is the differential amount of the large current on the primary side, so the Rogowski coil has differential characteristics. [0003] In today's transformer protection, due to the good performance of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/00G01R23/16
Inventor 叶曙光郭泉贺枫张志刚李春王宇森常新平汪斌
Owner 江苏金思源电气有限公司
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