Method for verifying polarity of zero-sequence current transformer

A zero-sequence current and transformer technology, which is applied in the field of verifying the polarity of zero-sequence current transformers, can solve the problems of time-consuming, manpower and material resources, and low efficiency, and achieve the effect of solving the difficulty of polarity detection

Inactive Publication Date: 2013-05-29
STATE GRID GANSU ELECTRIC POWER CORP DINGXI POWER SUPPLY CO +1
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Problems solved by technology

Since in actual engineering, there are as many as a dozen or even dozens of zero-sequence CTs, and the distance between transformers varies from several meters to more than ten meters, only one or a few can be calibrated at a time, so the efficiency of this method is very low , consumes a lot of ti

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  • Method for verifying polarity of zero-sequence current transformer

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Embodiment Construction

[0013] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and examples.

[0014] figure 1 The signal acquisition system processing flow chart shown includes the following steps:

[0015] In step 101, read the zero-sequence voltage of the bus and the zero-sequence current sampling values ​​of each line from the analog-to-digital converter A / D, and place them in a designated cache RAM;

[0016] In step 102, the voltage mutation amount is calculated according to the latest sampled value of the zero-sequence voltage collected, and the calculation method is as follows:

[0017] ΔU=U(k)-2U(k-N)+U(k-2N) (1)

[0018] In the formula (1), ΔU represents the sudden change value, U(k) represents the latest sampling value of the zero-sequence voltage, U(k-N) represents the sampling value before one cycle of wave, U(k-2N) represents the sampling value of two weeks before the wave, N represents weekly sampling poin...

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Abstract

The invention discloses a method for verifying a polarity of a zero-sequence current transformer. A hardware part comprises a signal acquisition system; a software part comprises a waveform analysis system; and the method comprises the following steps of: capturing an instant single-phase earth fault signal which mainly includes a bus zero-sequence voltage and a zero-sequence current of each line through the signal acquisition system by utilizing the characteristic of frequent instant single-phase earth fault of a distribution network system; and identifying whether a polarity connecting wire of the zero-sequence current transformer of each line is correct through the waveform analysis system based on the maximum zero-sequence amplitude value of a fault line and the characteristic that the phase position is opposite to that of the zero-sequence current of a non-fault line. The method for verifying the polarity of the zero-sequence current transformer solves the polarity verification difficulty of the zero-sequence current transformer in a small-current grounding line selection system efficiently without adding any device or tool, is very time-saving, convenient and fast, and solves a big difficulty in the practical application of small-current products.

Description

technical field [0001] The invention relates to the technical field of equipment manufacturing of a low-voltage distribution network of a power system, in particular to a method for verifying the polarity of a zero-sequence current transformer. Background technique [0002] Most of the 35kV and below low-voltage distribution networks in my country adopt the neutral point non-effective grounding method. The occurrence rate of single-phase ground faults in this type of power grid is very high, accounting for more than 70% of the total failure rate of the power system. After a single-phase ground fault occurs, it must be selected as soon as possible. Faulty lines are eliminated to ensure power operation and equipment safety. [0003] At present, there are many small current grounding line selection devices researched and developed in my country for single-phase ground fault line selection, but the overall line selection accuracy rate is less than 70%, which is difficult to meet ...

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Application Information

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IPC IPC(8): G01R35/02
Inventor 刘勇智刘海锋曾宇
Owner STATE GRID GANSU ELECTRIC POWER CORP DINGXI POWER SUPPLY CO
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