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Fault Judgment Method and Fault Protection Device for PT Disconnection and PT Three-phase Reverse Sequence

A fault judgment and fault protection technology, applied in the direction of measuring devices, instruments, motor generator testing, etc., can solve the problem of lack of fault detection such as the reverse sequence of PT output signals

Active Publication Date: 2021-07-06
CHINA YANGTZE POWER +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The PT fault judgment method of the existing generator excitation system usually detects and judges the disconnection of the PT signal, and lacks the detection of faults such as the reverse sequence of the PT output signal. For example, the Chinese patent with the publication number CN109541469A "A PT Disconnection Discrimination Method” discloses a method for judging PT disconnection by comparing the amplitude of two PT signals

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  • Fault Judgment Method and Fault Protection Device for PT Disconnection and PT Three-phase Reverse Sequence
  • Fault Judgment Method and Fault Protection Device for PT Disconnection and PT Three-phase Reverse Sequence
  • Fault Judgment Method and Fault Protection Device for PT Disconnection and PT Three-phase Reverse Sequence

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Embodiment Construction

[0040] Such as figure 1 , figure 2 As shown, the fault judgment method of PT disconnection and PT three-phase reverse sequence includes the following steps,

[0041] Step 1: Obtain the amplitude, period and phase angle difference between the three-phase voltage signal output by the PT through fixed-frequency sampling;

[0042] Step 2: Determine whether the average value of the three-phase voltage amplitude output by the PT is greater than the PT fault detection startup threshold;

[0043] If it is greater than the startup threshold and the duration is greater than the voltage stabilization threshold time, then perform step 3, otherwise perform step 1;

[0044] Step 3: Perform PT reverse order detection;

[0045] Step 4: Perform PT single-phase disconnection detection;

[0046] Step 5: Perform PT multi-phase disconnection detection.

[0047] In step 2, the PT fault detection startup threshold is 20% of the PT output three-phase rated voltage value.

[0048] In step 3, t...

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Abstract

The invention discloses a fault judging method for PT disconnection and PT three-phase reverse sequence, including sampling and acquiring the amplitude, period and phase angle difference of the three-phase voltage signal output by the PT; judging the three-phase voltage amplitude output by the PT Whether the average value of the value is greater than the PT fault detection startup threshold; perform PT reverse sequence detection; perform PT single-phase disconnection detection; perform PT multi-phase disconnection detection. The invention also discloses a fault protection device for PT disconnection and PT three-phase reverse sequence. The invention provides reverse sequence detection and judgment of PT output signals, outputs reverse sequence fault signal to the protection device, makes the automatic control system safer and more reliable; detects the disconnection fault of the PT output signal through the phase, reduces the possibility of false detection sex, more accurate and reliable.

Description

technical field [0001] The invention belongs to the field of relay protection for generating sets, and in particular relates to a fault judging method and a fault protection device for PT disconnection and PT three-phase reverse sequence. Background technique [0002] Potential transformer (PT), referred to as PT, is a sensor used for voltage measurement, which can reduce the signal amplitude and isolate the primary and secondary circuits. PT is widely used in many automatic control systems such as generator excitation device. [0003] The primary side of the PT is connected to the external high-voltage signal, and the secondary side is connected to the automatic control system. The normal PT signal is as follows: Figure 3-1 shown. From the on-site operation analysis, the failure probability of the primary side wiring is much higher than that of the secondary side. There are two types of PT primary side wiring faults, one is the wrong wiring sequence causing three-phase r...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/54G01R31/34
CPCG01R31/343G01R31/346
Inventor 王波余翔赵远孔丽君吴高强马小高
Owner CHINA YANGTZE POWER