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Internal and external fault pre-judgment method based on differential current change rate in dynamic process

A differential current and dynamic process technology, applied to electrical components, emergency protection circuit devices, etc., can solve the problem of less fault prediction and achieve the effect of strong practicability and high sensitivity of criteria

Active Publication Date: 2021-06-22
CENT CHINA BRANCH OF CHINA DATANG CORP SCI & TECH RES INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The premise of realizing the above assumption is that the feature quantity can be used to predict the faults inside and outside the zone at the initial stage of the fault. There are many studies on fault prediction based on fault components, and there are few studies on fault prediction based on phasor values.

Method used

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  • Internal and external fault pre-judgment method based on differential current change rate in dynamic process
  • Internal and external fault pre-judgment method based on differential current change rate in dynamic process
  • Internal and external fault pre-judgment method based on differential current change rate in dynamic process

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Experimental program
Comparison scheme
Effect test

Embodiment

[0033] The simulation experiment is carried out on the six unified RTDS experimental environment of the new information specification, and the performance of the prediction criterion is analyzed.

[0034] system model by image 3 build. Among them, the rated capacity of the transformer: 240MVA, the voltage level: 220 / 110 / 10kV; the short-circuit impedance (per unit value): X 12 =0.12,X 13 =0.38,X 23 = 0.22; CT transformation ratios of high, medium and low voltage sides are 1250 / 1, 2500 / 1, 4000 / 1 respectively; simulation system capacity is 10000MVA, after CT conversion, the rated current of high voltage side is I e = 0.5A.

[0035] Analyze the performance of the present invention's pre-judgment criterion below with respect to various typical operating conditions:

[0036] (1) 5% turn-to-turn fault of phase A of high-voltage winding and cut off (100 data points per cycle sampling)

[0037] Figure 4 (a) is the instantaneous value of the differential current of phase A, and...

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Abstract

The invention relates to an internal and external fault pre-judgment method based on a differential current change rate in a dynamic process, and the technical scheme is characterized by after phase current break variable protection is started, calculating a differential current Id and a braking current Ir of each sampling point by adopting a full-cycle Fourier algorithm, and calculating a ratio k of the differential current to the braking current at the first sampling point after the protection is started, if k belongs to [2-epsilon, 2+epsilon], judging as no-load closing, otherwise, starting from a second sampling point after protection startup, calculating the differential current change rate D, calculating m sampling points continuously, if the condition that D (i) is larger than or equal to Aet (i = 1, 2,... m) is always satisfied, judging as an internal fault, and otherwise, judging as an external fault. According to the present invention, the judgement sensitivity is higher, and the internal and external faults can be pre-judged within a 1 / 4 period (5ms) after protection is started.

Description

technical field [0001] The invention relates to a method for predicting internal and external faults, in particular to a method for predicting internal and external faults based on the rate of change of differential current in a dynamic process. Background technique [0002] Current differential protection is a protection that reflects the sum of the current flowing into the component from the external ports of the protected component. As the most ideal protection principle, it has been widely used in power system generators, transformers, busbars and short-distance transmission lines. protection of important electrical equipment. The current differential protection mostly adopts the ratio braking characteristic. After the ratio braking curve is established, for a fixed braking current value, the corresponding differential current operating value is determined. If the calculated differential current is actually If the value is greater than the differential current action va...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26
CPCH02H7/26Y04S10/52
Inventor 李姗姗张建华丁俊毅郑豫生
Owner CENT CHINA BRANCH OF CHINA DATANG CORP SCI & TECH RES INST CO LTD
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