Multi-component recombination current flashy flow judgment method of transformer and block relay

A compound current and transformer technology, applied in electrical components, emergency protection circuit devices, etc., can solve the problems of transformer differential protection protection misoperation and refusal, high second harmonic content, three-phase ratio differential, etc.

Active Publication Date: 2010-07-14
CENT CHINA GRID +1
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Problems solved by technology

Years of operating experience and tests have shown that there may be a phase with low second harmonic content, so the use of split-phase braking may easily lead to differential protection misoperation
[0009] "OR gate brake" may lead to differential protection refusal or delayed action
For example, when the transformer is closed on an internal single-phase fault, such as a phase A fault; phase B and phase C are non-fault phases, and there may be exciting inrush currents in phase B and phase C, and their second harmonic content is relatively high. Braking, therefore, will block the three-phase ratio differenti...

Method used

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  • Multi-component recombination current flashy flow judgment method of transformer and block relay
  • Multi-component recombination current flashy flow judgment method of transformer and block relay
  • Multi-component recombination current flashy flow judgment method of transformer and block relay

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Embodiment Construction

[0093] In order to make the above objects, features and advantages of the present invention more obvious and comprehensible, the technical solutions of the present invention will be described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0094] In order to enable those skilled in the art to implement the present invention better, several basic concepts are introduced first.

[0095] see figure 1 , which is a typical excitation inrush current waveform of a transformer.

[0096] From figure 1 Several characteristic quantities of the waveform can be seen in the figure: aperiodic component, discontinuity, and waveform distortion.

[0097] where aperiodic can be represented by figure 1 Most of the medium waveforms are seen on the negative half axis of the vertical axis, rather than being evenly distributed on the positive and negative half axes. Harmonics can be seen from the waveform. The ideal peak should be arc-shaped ...

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Abstract

The invention discloses a multi-component recombination current flashy flow block relay for identifying excitation flashy flow of a transformer, aiming at solving the problems of differential protection malfunction caused by excitation flashy flow during air delivery and rapid action of differential protection when a turn-to-turn fault occurs. The invention provides a multi-component recombination current flashy flow block relay which consists of sample current selection of the flashy flow, three-time harmonic infeed scheme, an electric scheme of the current harmonic ratio and self-adaptive flashy flow block criteria, wherein the action logic diagram of the relay is shown in the attached figure. The test result indicates that the relay has good sensitivity, safety and rapidness. The invention also discloses a recombination current flashy flow judgment method.

Description

technical field [0001] The invention relates to the field of transformer protection of relay protection technology, in particular to a transformer surge current blocking relay. Background technique [0002] At present, the differential protection of transformers mainly solves two problems in practice: one is to identify the inrush current and fault current; the other is to distinguish external faults from internal faults. The differential protection of transformers can better distinguish external faults and internal faults to a certain extent, but there are still some shortcomings in the identification of inrush current. [0003] At present, the current waveform is mainly used as the main basis for judging the excitation inrush current and fault current. Among various excitation inrush braking schemes, the second harmonic braking is relatively mature and reliable. The protection of main transformers at home and abroad is basically equipped with this discrimination method. ...

Claims

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Application Information

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IPC IPC(8): H02H7/045
Inventor 柳焕章屠黎明张德泉肖远清陈学道聂娟红李锋黄少锋冯勇尹梁方
Owner CENT CHINA GRID
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