CN100570977C - In a kind of transformer and the discrimination method of echo surge current - Google Patents
In a kind of transformer and the discrimination method of echo surge current Download PDFInfo
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- CN100570977C CN100570977C CNB200710303746XA CN200710303746A CN100570977C CN 100570977 C CN100570977 C CN 100570977C CN B200710303746X A CNB200710303746X A CN B200710303746XA CN 200710303746 A CN200710303746 A CN 200710303746A CN 100570977 C CN100570977 C CN 100570977C
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- 238000004804 winding Methods 0.000 claims abstract description 15
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- 238000005070 sampling Methods 0.000 claims description 2
- 230000007257 malfunction Effects 0.000 abstract description 8
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Abstract
In a kind of transformer and the discrimination method of echo surge current, belong to the power system main equipment technical field of relay protection, it is characterized in that: this method utilizes non-saturated region equivalent instantaneous inductor to differentiate transformer and echo surge current.The reason that produces according to transformer and echo surge current just in the phase current and the former side phase voltage of the former secondary both sides of operating transformer winding, and is calculated the poor of former and deputy both sides phase current, promptly poor stream with computer acquisition; Then in the computing cycle of setting, determine the unsaturation Operational Zone according to the maximum of difference stream absolute value; And then the equivalent instantaneous inductor in the calculating unsaturation Operational Zone, to differentiate operating transformer by the size of equivalent instantaneous inductor mean value in the non-saturated region and take place and echo surge current, Blocking Differential Protection prevents its malfunction.This method identification and echo surge current aspect is having reliability height, advantage that anti-current instrument transformer saturability strong than magnetizing inrush current locking criterion and triple-frequency harmonics than the saturated criterion of current transformer than second harmonic.
Description
Technical field
The invention belongs to the power system main equipment technical field of relay protection, relate in particular to a kind of transformer and the discrimination method of answering magnetizing inrush current.
Background technology
Transformer relay protecting is the guarantee of its safe and stable operation, but in the actual motion, owing to be subjected to the influence of many external conditions and principle aspect own, lower always as the differential protection performance factor of main protection.In numerous influencing factors; because a no-load transformer closes a floodgate; in the adjacent transformer that is moving, produce and echo surge current; and then cause the example of operating transformer differential protection malfunction repeatedly to take place, this concern that is just causing relaying protection circle by the differential protection malfunction phenomenon that causes with echo surge current because of its harmfulness, complexity, disguise.
At the malfunction that causes with echo surge current some precautionary measures have also been proposed, as suitable raising transformer differential protection definite value, disconnect the neutral ground of operating transformer or idle-loaded switching-on transformer.But the former can will hang down the sensitivity of differential protection, particularly is unfavorable for little shorted-turn fault protection action; The latter shows the path that can not eliminate with echo surge current after deliberation, can not avoid and the generation of echo surge current and the malfunction that causes transformer differential protection.Be accompanied by the saturated easier phenomenon that makes differential protection malfunction of current transformer when producing with echo surge current; the existing saturated criterion of increase current transformer that proposes prevents differential protection malfunction; improved the reliability of differential protection to a certain extent; but at present the saturated criterion of triple harmonic current instrument transformer that adopts itself exists insecure shortcoming; triple-frequency harmonics content is lower in the time of may differential protection malfunction in the reality, can not play braking action to differential protection.
At also not have at present special at the detection criteria and the measure of corresponding differential protection faulty action preventing of echo surge current; but with magnetizing inrush current (mainly being) criterion and the saturated criterion of current transformer at initially shoving that no-load transformer close a floodgate to produce; Blocking Differential Protection when producing with echo surge current, the effect in the reality is not fine.The present invention utilizes the transformer equivalent instantaneous inductor to differentiate transformer and echo surge current, improves the faulty action preventing ability of transformer differential protection.
Summary of the invention
The object of the present invention is to provide the discrimination method of a kind of transformer and echo surge current.
The discrimination method of a kind of transformer and echo surge current is characterised in that specifically this method realizes successively according to the following steps in computer:
(1) obtains the phase current and the former limit phase voltage of the former secondary both sides of operating transformer winding, and calculate the difference stream of both sides.
(2) choose transformer unsaturation Operational Zone.Getting 20ms is a computing cycle, selects the unsaturation Operational Zone.Difference stream i in one-period
dWhen all amesiality, get | i
d| maximum i
Dmax, choose | i
d|＜0.3i
DmaxThe zone is a non-saturated region; Difference stream i in one-period
dIn the time shaft both sides all sometimes, choose
As non-saturated region, I
NBe the transformer rated current.
(3) calculate equivalent instantaneous inductor in the non-saturated region
Wherein, k is the sampled point sequence number, and T is the sampling period, and u is the former limit phase voltage of transformer, i
dBe the difference stream that calculates by the phase winding electric current.
(4) if the interior equivalent instantaneous inductor average absolute L of operating transformer phase non-saturated region
Av〉=L
Th, and the differential protection criterion is satisfied, and then this takes place and echo surge current mutually; If mean value L
Av＜L
Th, then be short trouble, L
ThThreshold value for the non-saturated region equivalent instantaneous inductor mean value of discriminating and echo surge current and short trouble.Consider simplified formula and Practical Calculation error, and the reliability nargin of criterion, L selected
Th=2.5L
δ(L
δLeakage inductance for transformer).
This method identification and echo surge current aspect is having reliability height, advantage that anti-current instrument transformer saturability strong than magnetizing inrush current locking criterion and triple-frequency harmonics than the saturated criterion of current transformer than second harmonic.
Description of drawings
Fig. 1 is a transformer stage through transport row winding diagram in the embodiment of the invention, and wherein DL represents switch.
Fig. 2 is the phase current of operating transformer T1 both sides in the embodiment of the invention, wherein,---be primary current ... be secondary current.
Fig. 3 is the difference stream of T1 winding phase current in operating transformer both sides in the embodiment of the invention.
Fig. 4 is the harmonic analysis of operating transformer both sides T1 winding phase current difference stream in the embodiment of the invention, wherein,---be the A phase ... be the B phase,-----be the C phase.
Fig. 5 is the non-saturated region equivalent instantaneous inductor analysis of operating transformer T1 in the embodiment of the invention, also promptly and the identification result of echo surge current.
Fig. 6 is the flow chart of program in the embodiment of the invention.
Embodiment
Below in conjunction with accompanying drawing principle of the present invention and concrete execution mode are described once.
Fig. 1 transformer stage through transport row winding diagram.Wherein transformer T1 is in normal operating condition, and in a certain moment, transformer T2 carries out idle-loaded switching-on.To produce initial magnetizing inrush current in the idle-loaded switching-on transformer, will produce in the operating transformer and the echo surge current phenomenon.
Fig. 2 is the phase current of operating transformer T1 both sides in the embodiment of the invention.Behind the transformer T2 idle-loaded switching-on, the winding phase current (converting former limit) that transformer T1 both sides current transformer records, as can be seen from the figure, the secondary current instrument transformer takes place saturated, and it is seriously mutually saturated that A compares B, C.
Fig. 3 is the difference stream of operating transformer both sides winding phase current in the embodiment of the invention.Respectively differ stream by what the phase winding electric current calculated.
Fig. 4 is the harmonic analysis of operating transformer both sides winding phase current difference stream in the embodiment of the invention.According to real protection device electric current through the second harmonic in the difference stream that calculates after the phase transition, triple-frequency harmonics content ratio with first-harmonic; it is more higher than beginning that A differs in the stream second harmonic as can be seen; but along with current transformer saturated and and the appearance of echo surge current; make that the waveform of difference stream is approaching symmetrical; when about 0.33s, be lower than setting value 0.2; triple-frequency harmonics is lower than 0.2 than also simultaneously, so second harmonic all can not locking be lived A differential protection mutually than magnetizing inrush current locking criterion with the saturated criterion of triple harmonic current instrument transformer.Although B differs the triple-frequency harmonics process lower than having in the stream, because second harmonic is more higher than always, so can locking live B phase differential protection.C differ in the stream second harmonic than and triple-frequency harmonics than after the current transformer appearance is saturated, all be lower than 0.2 always, can't brake C phase differential protection.
Fig. 5 is operating transformer non-saturated region equivalent instantaneous inductor analysis in the embodiment of the invention, also promptly and the identification result of echo surge current.As can be seen from the figure, utilize the mean value of equivalent instantaneous inductor in each phase non-saturated region that the present invention calculates all to get L greater than threshold value
Th=2.5 * 0.08 * (2202/31.5)/314=0.98H.So can judge that this moment, operating transformer took place and echo surge current, differential protection is by reliable locking.
Fig. 6 is the flow chart of program in the embodiment of the invention, at first obtain operating transformer both sides electric current, the difference of calculating transformer both sides flows again, seek the non-saturated region in the transformer difference stream, calculate the mean value of equivalent instantaneous inductor in the non-saturated region, differentiate and echo surge current according to equivalent instantaneous inductor mean value size in the unsaturation.
Claims (2)
1, in a kind of transformer and the discrimination method of echo surge current, it is characterized in that described method realizes successively according to the following steps in computer:
Step (1). the current transformer of the former avris of operating transformer, secondary side is sent into described computer to the phase current of former limit winding, secondary winding respectively, simultaneously, describedly just former limit phase voltage is sent into described computer at the voltage transformer on the former limit of operating transformer;
Step (2). described computer calculates this just poor at the former limit of operating transformer winding, secondary winding phase current in computer, be referred to as difference stream;
Step (3). described computer is chosen this successively according to the following steps just in the unsaturation Operational Zone of operating transformer in the computing cycle of setting:
Step (3.1). the difference stream i in computing cycle
dWhen all being partial to time shaft one side, get difference stream absolute value | i
d| maximum, choose | i
d|＜0.3i
DmaxThe zone is a non-saturated region, i
DmaxMaximum for difference stream absolute value;
Step (3.2). the difference stream i in computing cycle
dIn the time shaft both sides all sometimes, choose
As non-saturated region, I
NFor just in the rated current of operating transformer;
Step (4). be calculated as follows the equivalent instantaneous inductor L in the unsaturation Operational Zone
k:
Wherein, k is the sampled point sequence number, u be this just in the former limit of operating transformer phase voltage, T is the sampling period;
Step (5). equivalent instantaneous inductor L in the unsaturation Operational Zone that determining step (4) obtains
kAverage absolute L
AvWhether more than or equal to preset threshold L
Th, L
Th=2.5L
δ, L
δFor this just in the leakage inductance of operating transformer:
L
Av＜L
Th, then be short trouble,
L
Av〉=L
Th, then for taking place and echo surge current.
2, in a kind of transformer according to claim 1 and the discrimination method of echo surge current, it is characterized in that described computing cycle is 20ms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB200710303746XA CN100570977C (en) | 2007-12-21 | 2007-12-21 | In a kind of transformer and the discrimination method of echo surge current |
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| Application Number | Priority Date | Filing Date | Title |
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| CNB200710303746XA CN100570977C (en) | 2007-12-21 | 2007-12-21 | In a kind of transformer and the discrimination method of echo surge current |
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| CN100570977C true CN100570977C (en) | 2009-12-16 |
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Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102097785B (en) * | 2010-12-30 | 2013-10-16 | 清华大学 | Method for authenticating sympathetic inrush current in traction substation transformer |
| CN102809681B (en) * | 2012-07-31 | 2015-01-07 | 许继电气股份有限公司 | Inrush current recognition method and low-voltage and medium-voltage quick disconnection protection method utilizing same |
| CN102879671B (en) * | 2012-09-17 | 2015-01-21 | 华北电力大学 | Method for judging inrush current locking of equivalent instantaneous inductance for protection of extra-high voltage regulating transformer |
| CN102946461A (en) * | 2012-10-31 | 2013-02-27 | 昆山富泰科电脑有限公司 | Method and graphic interface for quickly recording memorandum during calling of communication device |
| CN103336197B (en) * | 2013-06-20 | 2017-06-30 | 国家电网公司 | A kind of method of discrimination of inrush current of transformer locking |
| CN105048413B (en) * | 2015-03-09 | 2017-11-28 | 国网山西省电力公司电力科学研究院 | In a kind of tranformer protection and echo surge current discrimination method |
| CN105552839B (en) * | 2016-03-07 | 2018-01-12 | 国家电网公司 | It is a kind of based on transformer of the voltage in line integral and echo surge current recognition methods |
| CN107765076B (en) * | 2016-08-19 | 2021-01-15 | 中国电力科学研究院 | Magnetizing inrush current identification method and device |
| CN106711947A (en) * | 2017-01-10 | 2017-05-24 | 许继集团有限公司 | Sympathetic inrush current identification method based on station territory difference current |
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2007
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Non-Patent Citations (6)
| Title |
|---|
| 变压器和应涌流的理论探讨. 毕大强，王祥珩，李德佳，余高旺，王赞基，王维俭.电力系统自动化，第29卷第6期. 2005 |
| 变压器和应涌流的理论探讨. 毕大强，王祥珩，李德佳，余高旺，王赞基，王维俭.电力系统自动化，第29卷第6期. 2005 * |
| 基于非饱和区等效瞬时电感的变压器励磁涌流鉴别方法. 毕大强，王祥珩，王剑，余高旺，王维俭.电力自动化设备，第25卷第10期. 2005 |
| 基于非饱和区等效瞬时电感的变压器励磁涌流鉴别方法. 毕大强，王祥珩，王剑，余高旺，王维俭.电力自动化设备，第25卷第10期. 2005 * |
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