CN104242242A - Method for calculating three-side longitudinal difference protection braking current of tail-end transformer of power system - Google Patents
Method for calculating three-side longitudinal difference protection braking current of tail-end transformer of power system Download PDFInfo
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- CN104242242A CN104242242A CN201410497685.5A CN201410497685A CN104242242A CN 104242242 A CN104242242 A CN 104242242A CN 201410497685 A CN201410497685 A CN 201410497685A CN 104242242 A CN104242242 A CN 104242242A
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- transformer
- longitudinal difference
- protection
- difference protection
- tail
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Abstract
The invention relates to longitudinal difference protection of tail-end transformers of power systems and differential protection of electric furnace transformers or rectifier units, in particular to a method for calculating three-side longitudinal difference protection braking current of a tail-end transformer of a power system. The method is characterized in that braking current (img file='DDA0000576666870000011.TIF' wi='568'he='128' /), (img file='DDA0000576666870000012.TIF' wi='308' he='88' /) sequentially is same-phase current vectors on high, middle and low voltage sides of the transformer. The method has the advantages that action sensitivity of protection is quite high when the transformer longitudinal difference protection inside is in a short circuit, and the defect that a conventional transformer adopts an Ires algorithm is overcome; when the transformer longitudinal difference protection outside is in a short circuit, a braking current Ires value of the method is completely identical with an Ires value of the conventional algorithm, so that reliability that longitudinal difference protection of the tail-end transformer is free of misoperation is ensured to be identical in the method and the conventional algorithm.
Description
Technical field
The present invention relates to electric power system end transformer differential protection, furnace transformer or Rectification Power Factor differential protection, especially a kind of electric power system end transformer three side longitudinal difference protection stalling current computational methods.
Background technology
High-power electric arc furnace application enterprise, the direct powering mode of general employing furnace transformer-arc furnace, namely furnace transformer directly accesses the electrical network of 110kV, 220kV even more voltage levels, after furnace transformer step-down, provides the electric current reaching ten myriampere degrees to smelt to arc furnace.
In metallurgical, electrochemistry enterprise, in production, the general high-power rectifying device that adopts is powered.By the high-voltage alternating inlet wire of 35-500kV electric pressure, through voltage regulating transformer-rectifier transformer group step-down pressure regulation, the direct current adjustable by silicon rectifier device supply production system voltage, electric current reaches hundreds of kilo-ampere.
The three-winding transformer of current high-voltage electric power system (no matter transformer three side have power supply or both sides have power supply or only side have power supply) the differential current I of Microcomputer Differential Current Protection
op, stalling current I
resadopt the traditional algorithm that formula-(1) is expressed all without exception:
In formula,
for transformer high, medium and low voltage side phase current vector of the same name.Current high-voltage electric power system end three winding step-down transformer (its high-pressure side and electric power system are connected with power supply, and in and low-pressure side power to load non-transformer) the I of Microcomputer Differential Current Protection
op, I
resalso the traditional algorithm of above formula-(1) is adopted.
Furnace transformer, rectifier transformer unit are system end transformer, and its high pressure winding and system are connected with power supply, and medium voltage side and low-pressure side are powered to load non-transformer.The stalling current I of this transformer three side Microcomputer Differential Current Protection
resif continue to use the method for transformer in electric power system
when shortcoming is transformer differential protection internal short-circuit, protection act sensitivity is low.
Summary of the invention
The object of this invention is to provide a kind of electric power system end transformer three side longitudinal difference protection stalling current computational methods, the action sensitivity protected when can realize transformer differential protection internal short-circuit when not reducing reliability is very high.
A kind of electric power system end transformer three side longitudinal difference protection stalling current computational methods, its special feature is: stalling current
in formula,
be followed successively by transformer high, medium and low voltage side phase current vector of the same name.
The present invention proposes a kind of new computational methods being applicable to electric power system end transformer differential protection stalling current, the action sensitivity protected when its advantage is transformer differential protection internal short-circuit is very high, overcomes traditional transformer I
resthe shortcoming of algorithm, and when transformer differential protection external short circuit the stalling current I of new algorithm
resthe I of value and traditional algorithm
resbe worth identical, the two ensures that the reliability of end transformer differential protection not malfunction is identical.
Embodiment
Stalling current I of the present invention
resthe Microcomputer Differential Current Protection that new algorithm is applicable to metallurgy, chemical industry uses the end such as furnace transformer, Rectification Power Factor three winding step-down transformer, high-pressure side and the electric power system of these transformers are connected with power supply, and middle pressure and low-pressure side are powered to load non-transformer.
Three winding step-down transformer for electric power system end (comprises general power transformer, furnace transformer, rectifier transformer etc.; its common feature be high-pressure side have power supply and in and low-pressure side non-transformer) Microcomputer Differential Current Protection, the present invention proposes differential current I
op, stalling current I
resnew algorithm, be specially formula-(2):
The I of formula-(2)
opwith the I of background technology Chinese style-(1)
opidentical, but the I of formula-(2)
reswith the I of traditional type-(1)
resremarkable difference, this is core content of the present invention.
Have power supply with high pressure winding below and mesolow winding power free three winding step-down transformer is protected object, the performance of analysis background technology Chinese style-(1) and formula-(2) longitudinal difference protection is good and bad.
(1) longitudinal difference protection scope internal short-circuit:
be followed successively by transformer high, medium and low voltage side phase current vector of the same name, I
hfor short circuit current, I
in=I
l=0;
See formula-(1),
See formula-(2),
Visible, when internal short-circuit, differential current I of the present invention
opwith the I of traditional algorithm
opbeing worth identical, is all I
h(short circuit current), but stalling current of the present invention
the I of traditional algorithm
res=I
h, the former is I
resbe only the half of the latter, so I of the present invention during internal short-circuit
resnew algorithm can make the sensitivity of protection act be significantly higher than conventional I
resprotection sensitivity, this is advantage of the present invention.
(2) longitudinal difference protection scope outside (as outside medium voltage side) short circuit
be followed successively by transformer high, medium and low voltage side phase current vector of the same name, I
h=I
in=I
d(I
dlongitudinal difference protection scope external short circuit current value), I
l=0;
See formula-(1),
See formula-(2),
Visible, when external short circuit, I of the present invention
op, I
resthe I of value and traditional algorithm
op, I
resvalue is identical respectively, and both reliabilities that longitudinal difference protection is failure to actuate are identical.
Claims (1)
1. electric power system end transformer three side longitudinal difference protection stalling current computational methods, is characterized in that: stalling current
in formula,
be followed successively by transformer high, medium and low voltage side phase current vector of the same name.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410497685.5A CN104242242A (en) | 2014-09-25 | 2014-09-25 | Method for calculating three-side longitudinal difference protection braking current of tail-end transformer of power system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410497685.5A CN104242242A (en) | 2014-09-25 | 2014-09-25 | Method for calculating three-side longitudinal difference protection braking current of tail-end transformer of power system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104242242A true CN104242242A (en) | 2014-12-24 |
Family
ID=52229835
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410497685.5A Pending CN104242242A (en) | 2014-09-25 | 2014-09-25 | Method for calculating three-side longitudinal difference protection braking current of tail-end transformer of power system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104242242A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110768212A (en) * | 2019-10-25 | 2020-02-07 | 南方电网科学研究院有限责任公司 | Transformer internal short-circuit fault protection device and control method thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3754163A (en) * | 1971-09-24 | 1973-08-21 | J Sykes | Protection of transformers |
| CN101183783A (en) * | 2007-12-14 | 2008-05-21 | 国电南京自动化股份有限公司 | Graded hyperbolic anti-TA transient saturation differential protection method |
| CN101800415A (en) * | 2010-04-27 | 2010-08-11 | 宁夏回族自治区电力公司 | Longitudinal differential protection method of electric furnace transformer |
| CN103457242A (en) * | 2013-08-08 | 2013-12-18 | 许继集团有限公司 | Electric furnace transformer longitudinal differential protection secondary current compensation method |
-
2014
- 2014-09-25 CN CN201410497685.5A patent/CN104242242A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3754163A (en) * | 1971-09-24 | 1973-08-21 | J Sykes | Protection of transformers |
| CN101183783A (en) * | 2007-12-14 | 2008-05-21 | 国电南京自动化股份有限公司 | Graded hyperbolic anti-TA transient saturation differential protection method |
| CN101800415A (en) * | 2010-04-27 | 2010-08-11 | 宁夏回族自治区电力公司 | Longitudinal differential protection method of electric furnace transformer |
| CN103457242A (en) * | 2013-08-08 | 2013-12-18 | 许继集团有限公司 | Electric furnace transformer longitudinal differential protection secondary current compensation method |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110768212A (en) * | 2019-10-25 | 2020-02-07 | 南方电网科学研究院有限责任公司 | Transformer internal short-circuit fault protection device and control method thereof |
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| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20141224 |
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| RJ01 | Rejection of invention patent application after publication |