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Transient-state quantity polarity comparison type bus protection method on basis of sequence overlapping and differential transformation

A technology of overlapping differential and busbar protection, applied in the direction of measuring electrical variables, measuring electricity, measuring devices, etc., can solve problems such as poor anti-CT saturation capability, and achieve the effect of high reliability, good effect, and accurate judgment.

Active Publication Date: 2017-01-25
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The existing microcomputer busbar protection is generally based on the power frequency current, and the protection can basically meet the reliability and selectivity requirements of the system, but it faces the problem of poor anti-CT saturation ability

Method used

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  • Transient-state quantity polarity comparison type bus protection method on basis of sequence overlapping and differential transformation
  • Transient-state quantity polarity comparison type bus protection method on basis of sequence overlapping and differential transformation
  • Transient-state quantity polarity comparison type bus protection method on basis of sequence overlapping and differential transformation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] Example 1: Take figure 1 In the simulation model, a metallic single-phase ground fault occurs on the bus M, the sampling frequency is 500kHz, F1 and F2 are A-phase metallic ground faults, and the initial fault angle is 90°. The bus-side current transformers CT1, CT2, CT3 constitute the bus-bar M side protection. The three-phase current and the three-phase voltage are respectively subjected to phase-to-mode conversion to obtain the line-mode current and line-mode voltage of the faulty phase.

[0053] The specific steps of the method are:

[0054] 1. When the bus or line fails, the measuring unit will take the bus voltage data from 1ms before the failure to 2ms after the failure and the current data of each line;

[0055] 2. Perform sequence overlap and differential transformation on the fault signal; transform the line mode voltage and line mode current according to the sequence overlap difference method, and the conversion results are Su(n) and Si(n);

[0056] 3. Calculate SP...

Embodiment 2

[0059] Example 2: Take figure 1 In the simulation model, a metallic single-phase grounding fault occurs at bus M, and the sampling frequency is 500kHz. A metallic single-phase grounding fault occurs at line L1 at a distance of 70km from bus M. The initial angle of the fault is 90° bus-side current transformer CT1 CT2 and CT3 constitute the M side protection of the bus. The three-phase current and the three-phase voltage are respectively subjected to phase-to-mode conversion to obtain the line-mode current and line-mode voltage of the faulty phase.

[0060] The calculated current measured at each measuring point on the bus M and the calculated result are as follows image 3 Shown.

[0061] From the simulation results, it can be seen that the current sudden change direction of the faulty line is opposite to the current sudden change direction of the healthy line. The calculation result is 1, which is judged as a line fault, which is consistent with the assumption, and the judgment ...

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Abstract

The invention relates to a transient-state quantity polarity comparison type bus protection method on the basis of sequence overlapping and differential transformation, and belongs to the field of relay protection technologies for electric power systems. The transient-state quantity polarity comparison type bus protection method includes extracting voltage and current signals of various lines connected with bus when faults of the lines or the bus occur and computing line-mode voltages and line-mode currents by the aid of three-phase voltages and currents; carrying out sequence overlapping and differential transformation on the line-mode voltages and the line-mode currents of the various lines, solving differential transformation voltages and differential transformation currents, carrying out sign function transformation on product results of the differential transformation voltages and the differential transformation currents to obtain sgn(SP<k>), adding the sgn(SP<k>) of all the lines connected with the bus, acquiring absolute values to obtain values and determining that the faults of the lines occur if the values are smaller than the quantities of current transformers; determining that the faults of the bus occur if the values are equal to the quantities of the current transformers. The line-mode voltages and the line-mode currents comprise fault phases.

Description

Technical field [0001] The invention relates to a transient quantity polarity comparison type bus protection method based on sequence overlapping differential conversion, and belongs to the technical field of power system relay protection. Background technique [0002] Bus protection is an important part of power system relay protection. If the bus fault is handled improperly or not in time, it will cause a large-scale blackout, which will damage the electrical equipment and cause serious economic losses. Bus failure is a very serious failure in the power system, which directly affects the safe and reliable operation of all equipment connected to the bus. With the continuous development of power system technology, the voltage level of the power grid continues to rise, and the requirements for the rapidity, sensitivity, reliability, and selectivity of the busbar protection are getting higher and higher. [0003] The existing microcomputer bus protection is generally based on the p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/02
CPCG01R31/50
Inventor 束洪春孟祥斐曹璞璘陈诺
Owner KUNMING UNIV OF SCI & TECH
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