Broken wire detecting method for voltage transformer

A voltage transformer and disconnection detection technology, which is applied in the direction of instruments, measuring electricity, measuring devices, etc., can solve the problem of no applicable method for disconnection detection of voltage transformers, and achieves simplified disconnection detection methods, high reliability, Wide range of effects

Inactive Publication Date: 2005-06-22
SHANDONG KEHUI POWER AUTOMATION +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the method of voltage transformer disconnection detection is basically only for a specific type of wiring voltage transformer, and there is no method for voltage transformer disconnection detection suitable for various wiring methods

Method used

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  • Broken wire detecting method for voltage transformer
  • Broken wire detecting method for voltage transformer
  • Broken wire detecting method for voltage transformer

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Embodiment Construction

[0028] figure 1 , figure 2 The two wiring methods of voltage transformers (hereinafter referred to as PT) commonly used in railway automatic block power distribution are shown. The three-phase equivalent circuit of the PT secondary side is as follows: Figure 3 ~ Figure 6 As shown, there are 4 ways of Y-Y connection, Y-Δ connection, Δ-Y connection and Δ-Δ connection. Figure 7 , Figure 8 The normal working voltage vector diagrams of Y-connection and Δ-connection voltage transformers are respectively. The following are the amplitude characteristics of the line voltage of the PTs in the four connection modes when the line is broken.

[0029] a. Three-phase disconnection: When all three phases of PT are disconnected, theoretically U ab , U bc , U ca The amplitude of the voltage is zero, and the engineering generally takes the voltage amplitude to be less than 15-30% U e That is to say, there is no pressure.

[0030] b. Two-phase disconnection

[0031] (1) Y-Y type con...

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Abstract

A method for detecting disconnection of a voltage transformer is suitable for detection of disconnection of a voltage transformer in a small current grounding system of a power network. Including the following steps: (1) Collect voltage signals from voltage transformers, and obtain line voltage U through calculation ab , U bc , U ca (2) collect the load current signal from the current transformer; compare the amplitude relationship of voltage and current to determine that the voltage transformer is disconnected; it is characterized in that: use the amplitude relationship of the three line voltages to judge the voltage transformer disconnection, The maximum amplitude of the three line voltages U Lma Greater than or equal to the minimum amplitude U of the three line voltages Lmin n times of , where 1<n≤1.732, namely U Lmax ≥n×U Lmin , it is determined that the voltage transformer is disconnected. The method is suitable for various wiring modes, especially for disconnection detection of voltage transformers with Y-Y type and Δ-Δ type wiring, and is convenient to realize on general microcomputer protection, measurement and control, and automatic devices.

Description

technical field [0001] The invention relates to a disconnection detection method of a voltage transformer in a small current grounding system of a power network, in particular to a detection method for a disconnection of a voltage transformer of a Y-Y type and a Δ-Δ type connection. Background technique [0002] The task of the voltage transformer is to accurately transform the very high voltage to the allowable voltage of the secondary protection and the secondary instrument (generally 100V), so that the relay and the instrument can work under low voltage and accurately reflect the power Operation of high-voltage equipment in the system. [0003] There are many wiring methods for voltage transformers, and sometimes there are voltage transformers with multiple wiring methods in the same substation. Potential transformer disconnection is one of the more common faults. When a potential transformer disconnection fault occurs, the corresponding protection and automatic device ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/02G01R35/02
Inventor 张怿宁陈平徐丙垠索南加乐
Owner SHANDONG KEHUI POWER AUTOMATION
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