CN105280331B - Transformer iron core demagnetization method - Google Patents
Transformer iron core demagnetization method Download PDFInfo
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- CN105280331B CN105280331B CN201510756624.0A CN201510756624A CN105280331B CN 105280331 B CN105280331 B CN 105280331B CN 201510756624 A CN201510756624 A CN 201510756624A CN 105280331 B CN105280331 B CN 105280331B
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Abstract
The invention discloses a transformer iron core demagnetization method and especially provides a method for demagnetizing the iron core of a transformer after the DC resistance test. According to the invention, the voltage is applied onto the primary winding of a transformer by a DC power supply for three times, wherein the voltage-applying amplitude is the same each time and the polarity thereof is alternately changed. The voltage-applying duration is determined based on the acquired current waveform of the primary side of the transformer. During the first two times, the current applied onto the primary winding of the transformer reaches a forward peak value and a reverse peak value respectively. During the third time, the current applied onto the primary winding of the transformer occupies only half of the duration from the forward peak value to 63.2% of the reverse peak value. Through the above three voltage application processes, the iron core of the transformer is demagnetized. Based on the above method, the demagnetization duration is greatly shortened and the demagnetization effect is ensured at the same time. Meanwhile, the demagnetization equipment is small in power and good in practicality.
Description
Technical field
The invention belongs to transformator residual technique field, and in particular to a kind of transformer core demagnetizing method.
Background technology
According to《Power equipment preventive trial code》Require, high-power transformer after maintenance or operation 1 to 3 year after, all
DC Resistance Test of Transformer to be carried out, as the magnetic field that DC current is produced will make transformer core leave a large amount of remanent magnetism.
During transformer during no-load closing, affected by iron core remanent magnetism and breaker closing phase angle, be likely to result in the saturation of iron core, cause transformator
Very big excitation surge current is produced in the side of voltage jump, is caused differential protection misoperation to trip, is made putting into operation repeatedly for transformator
Failure；The very big excitation surge current of numerical value also results in transformator and chopper because electric power is excessive and impaired；Induction is adjacent to other
Transformator that transformer station etc. is currently running produces " and echo surge current " and mistrip, causes large-area power-cuts；A large amount of harmonic waves therein
Serious pollution will also result in the electrical network quality of power supply.Therefore iron core should be demagnetized after transformator directly hinders test.
Remanent magnetism is produced has hysteresis characteristic mainly due to transformer fe core material.Transformator main magnetic circuit typically adopts magnetic conductivity
Higher can make with the less stalloy of core loss.When being placed on remagnetization in alternating magnetic field, rising magnetization curve with
Decline magnetization curve is misaligned, and the change of magnetic flux density B during decline always lags behind the change of magnetic field intensity H, when H drops to zero
When, B does not drop to zero but drops to a certain numerical value Br, this phenomenon is referred to as magnetic hysteresis.BrReferred to as residual magnetic flux density, referred to as
Remanent magnetism.If can ensure that scene temperature will not be mutated the curie point more than iron core while the electromagnetic noise very little at scene, not enough
To affect the change in magnetic field, it is possible to think remanent magnetism hardly time to time change.
The transformer core demagnetizing method for adopting domestic at present is usually strong more than remanent magnetism magnetization to transformator applying one
The magnetic field H of degree, is then constantly changing magnetic direction and is gradually reduced magnetic field intensity to null value (by applying alternation to transformator
And the curtage decayed is completed), make the B-H hysteresis curves of generation that zero process is progressively decremented in additional magnetic field amplitude
In, hysteresis ring is reduced, magnetic flux is gradually less, finally close to zero.But it is long the time required to the method demagnetization, and easily changing magnetic
Cause hysteresis ring to shift during field direction and size, cause degaussing to fail, can even increase sometimes transformator and remain
Magnetic.
The content of the invention
In order to solve the problems, such as above-mentioned prior art, the present invention provides a kind of transformer core demagnetizing method.The party
Method only can need to complete iron core demagnetization to three pressurizations of Transformer Winding by DC source, while ensure that demagnetization effectiveness
The demagnetization time is substantially reduced, and demagnetizer power is little, with practicality.
In order to achieve the above object, the present invention is adopted the following technical scheme that：
A kind of transformer core demagnetizing method, comprises the steps：
Step 1：Pressurizeed to transformer primary side winding by DC source, signal pickup assembly is by transformer to transformator
Voltage current waveform is sampled, when primary current no longer increases, controller record saturation current peak value isatAnd by switch
Circuit upset transformer primary side winding voltage polarity pressurization, starts timing；
Step 2：When primary current is reverse and reaches -63.2%isatWhen, stop timing, a length of Δ t during record；Continue to add
It is depressed into primary current and reaches-isatAnd no longer increase, controller is again by on-off circuit upset transformer primary side winding voltage pole
Property, when this pressurization duration reaches Δ t/2, DC source is closed, complete demagnetization.
Compared to the prior art compared with the present invention possesses following advantage：
1st, it is short the time required to demagnetization.
2. demagnetize by the initial remanent magnetism of iron core need not be predicted, and demagnetization effectiveness is preferable.
Description of the drawings
Fig. 1 is demagnetization process flow diagram flow chart.
Fig. 2 is demagnetizer figure.
Fig. 3 is demagnetization equivalent circuit diagram.
Fig. 4 is single-phase transformer demagnetization phantom.
Fig. 5 is demagnetization DC voltage waveform figure.
Fig. 6 is transformer core flux waveformses figure.
Specific embodiment
The present invention is described in detail with reference to the accompanying drawings and examples：
As depicted in figs. 1 and 2, the invention discloses a kind of transformer core demagnetizing method, comprises the steps：
Step 1：Pressurizeed to transformer primary side winding by DC source, signal pickup assembly is by transformer to transformator
Voltage current waveform is sampled, when primary current no longer increases, controller record saturation current peak value isatAnd by switch
Circuit upset transformer primary side winding voltage polarity pressurization, starts timing；
Step 2：When primary current is reverse and reaches -63.2%isatWhen, stop timing, a length of Δ t during record；Continue to add
It is depressed into primary current and reaches-isatAnd no longer increase, controller is again by on-off circuit upset transformer primary side winding voltage pole
Property, when this pressurization duration reaches Δ t/2, DC source is closed, complete demagnetization.
Present invention demagnetization principle is illustrated with reference to the demagnetization equivalent circuit of Fig. 3：
When pressurizeing to transformer primary side winding for the first time, iron core magnetic flux constantly increases, when primary current no longer increases, ferrum
Core saturation, reaches maximum magnetic fluxPrimary side winding induced voltage can be obtained is
Primary current is
Wherein L is transformer core equivalent inductance, and U is DC voltage amplitude, and R is DCR of Transformer, i be former limit around
Group electric current.
Primary side winding applied voltage polarity is now overturn, gives transformator second pressurization.According to DC circuit threefactor method
Analysis can be obtained：
WhereinAccording to the law of electromagnetic induction,
From formula (6), to transformator it is additional when it is a length ofDC voltage U can make transformer core magnetic flux by
It is kept to zero.
As t=τ,
I=-63.2%Isat (7)
Therefore primary current is from positive peak value i in second pressure process of recordsatTo -63.2%isatRequired time Δ t；Together
Shi Jixu is forced into primary current and reaches-isatAnd controller overturns transformer primary side again by on-off circuit after no longer increasing
Winding voltage polarity is pressurizeed to transformator third time；Make by this Δ t/2 duration that need to pressurize transformer core magnetic flux byZero is transitted to, power supply is closed afterwards and is completed demagnetization.
Embodiment
By taking single-phase transformer demagnetization as an example, phantom as shown in Figure 4 is built, in figure：U represents DC source, R tables
Show DCR of Transformer, n indication transformer no-load voltage ratios, L1Indication transformer leakage inductance, L2The equivalent magnetizing inductance of indication transformer, P
Indication transformer high-pressure side, S indication transformer low-pressure sides；Transformator rated capacity is 403MVA, and rated voltage is 199.18kV/
162.64kV, high-pressure side rated flux are 634V*s, and DCR of Transformer is 0.08 Ω, is moved back from high voltage side of transformer
Magnetic, demagnetization DC voltage amplitude are 8V, and initial remanent magnetism is -500V*s, is demagnetized by the inventive method, and Fig. 5 is demagnetization direct current
Voltage oscillogram, Fig. 6 are transformer core flux waveformses.It can be seen that can complete iron core demagnetization through about 600s, after demagnetization, iron core is remained
Magnetic is 6V*s, and demagnetization effectiveness is good.
The specific embodiment of the present invention is described above in association with accompanying drawing, but these explanations can not be understood to limit
The scope of the present invention, protection scope of the present invention is limited by appended claims, any in the claims in the present invention base
Change on plinth is all protection scope of the present invention.
Claims (1)
1. a kind of transformer core demagnetizing method, it is characterised in that：Comprise the steps：
Step 1：Pressurizeed to transformer primary side winding by DC source, signal pickup assembly is by transformer to transformator electricity
Pressure, current waveform are sampled, when primary current no longer increases, controller record saturation current peak value isatAnd by switch
Circuit upset transformer primary side winding voltage polarity pressurization, starts timing；
Step 2：When primary current is reverse and reaches -63.2%isatWhen, stop timing, a length of Δ t during record；Continue to be forced into
Primary current reaches-isatAnd no longer increase, controller overturns transformer primary side winding voltage polarity again by on-off circuit,
When this pressurization duration reaches Δ t/2, DC source is closed, demagnetization is completed.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510756624.0A CN105280331B (en) | 2015-11-06 | 2015-11-06 | Transformer iron core demagnetization method |
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| CN201510756624.0A CN105280331B (en) | 2015-11-06 | 2015-11-06 | Transformer iron core demagnetization method |
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| CN105280331A CN105280331A (en) | 2016-01-27 |
| CN105280331B true CN105280331B (en) | 2017-03-22 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111929626B (en) * | 2019-04-25 | 2023-03-28 | 南京南瑞继保电气有限公司 | Transformer residual magnetism estimation device and method |
| CN112117125B (en) * | 2020-08-27 | 2022-04-08 | 江门市蓬江区恒驰新材料有限公司 | Automatic change coil and twine sticky tape equipment |
| CN112967862B (en) * | 2021-03-23 | 2023-02-07 | 西安热工研究院有限公司 | J-A model-based three-phase transformer demagnetization method |
| CN114141471B (en) * | 2021-12-08 | 2023-12-05 | 杭州电力设备制造有限公司 | Demagnetizing system, method, device and medium |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1887527A (en) * | 2006-07-27 | 2007-01-03 | 西安鸣士机电开发有限公司 | Grinder chuck magnetizing and demagnetizing controller |
| CN103632804A (en) * | 2013-12-11 | 2014-03-12 | 国家电网公司 | Method and system for degaussing power transformer |
| CN104833928A (en) * | 2015-04-30 | 2015-08-12 | 国网四川省电力公司电力科学研究院 | Large-scale power transformer residual magnetism detection method |
| CN104916389A (en) * | 2015-07-03 | 2015-09-16 | 江苏容天机电科技有限公司 | Large-power unidirectional excitation pulse transformer demagnetizer |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9704637B2 (en) * | 2013-07-15 | 2017-07-11 | Texas Instruments Incorporated | Method and apparatus for demagnetizing transformer cores in closed loop magnetic current sensors |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1887527A (en) * | 2006-07-27 | 2007-01-03 | 西安鸣士机电开发有限公司 | Grinder chuck magnetizing and demagnetizing controller |
| CN103632804A (en) * | 2013-12-11 | 2014-03-12 | 国家电网公司 | Method and system for degaussing power transformer |
| CN104833928A (en) * | 2015-04-30 | 2015-08-12 | 国网四川省电力公司电力科学研究院 | Large-scale power transformer residual magnetism detection method |
| CN104916389A (en) * | 2015-07-03 | 2015-09-16 | 江苏容天机电科技有限公司 | Large-power unidirectional excitation pulse transformer demagnetizer |
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