CN108429229A - The method of discrimination of no-load transformer excitation surge current during breaker phase selection reclosing - Google Patents
The method of discrimination of no-load transformer excitation surge current during breaker phase selection reclosing Download PDFInfo
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- CN108429229A CN108429229A CN201810393999.9A CN201810393999A CN108429229A CN 108429229 A CN108429229 A CN 108429229A CN 201810393999 A CN201810393999 A CN 201810393999A CN 108429229 A CN108429229 A CN 108429229A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/04—Arrangements for preventing response to transient abnormal conditions, e.g. to lightning or to short duration over voltage or oscillations; Damping the influence of dc component by short circuits in ac networks
- H02H1/046—Arrangements for preventing response to transient abnormal conditions, e.g. to lightning or to short duration over voltage or oscillations; Damping the influence of dc component by short circuits in ac networks upon detecting saturation of current transformers
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Abstract
The invention discloses a kind of method of discrimination of no-load transformer excitation surge current during breaker phase selection reclosing, specific steps include：When overcurrent occurring during breaker phase selection reclosing, it is based on the combined floodgate number of phases and combined floodgate phase current feature, establishes equivalent circuit and relevant voltage equation；According to voltage, current sampling data, calculates the equivalent inductance value of each sampling instant and take its average value；By average equivalent inductance value and threshold value comparison, it is excitation surge current situation when more than or equal to threshold value, is short circuit fault condition when being less than threshold value, if average equivalent inductance value more than one, it is excitation surge current situation when average equivalent inductance value is all greater than equal to threshold value, is otherwise short circuit fault condition.The present invention can accurately identify no-load transformer excitation surge current during breaker phase selection reclosing, effectively improve fault identification accuracy rate and reclosing success rate.
Description
Fields
The present invention relates to a kind of method of discrimination of no-load transformer excitation surge current during breaker phase selection reclosing, belong to
Vacuum circuit breaker field.
Background technology
Automatic reclosing is widely used in electric system, i.e., after circuit breaker trip can automatically by breaker again
It closes a floodgate, when coinciding with permanent fault, breaker is again off circuit.Phase-controlled technology can realize that breaker split-phase is closed
Lock and particular phases close a floodgate.When, there are when no-load transformer, breaker phase selection reclosing may to become in electric system
Depressor iron circuit is seriously saturated, and transformer magnetizing current sharply increases, and excitation surge current phenomenon occurs.Excitation surge current may reach
To several times of rated current, open circuit fault may be mistaken for.High-power transformer uses secondary harmonic brake and interval angle at present
The methods of braking identification excitation surge current, but protective device cannot be avoided to malfunction completely, and also these methods are only applied to
Three-phase synchronous combined floodgate situation lacks applicability for breaker phase selection reclosing process.
Invention content
Technical problem：In order to overcome the deficiencies in the prior art, the present invention to provide a kind of breaker phase selection reclosing
The method of discrimination of no-load transformer excitation surge current in the process.When solving breaker phase selection reclosing, no-load transformer excitation surge current
The problem of being mistaken for short trouble, leading to phase selection unsuccessful reclosing.
Technical solution：To achieve the above object, no-load transformer during a kind of breaker phase selection reclosing of the invention
The method of discrimination of excitation surge current includes the following steps：When overcurrent occurring during breaker phase selection reclosing, based on combined floodgate
The number of phases and combined floodgate phase current feature, establish equivalent circuit and relevant voltage equation；According to voltage, current sampling data, calculate each
The equivalent inductance value of sampling instant simultaneously takes its average value；By average equivalent inductance value and threshold value comparison, it is when more than or equal to threshold value
Excitation surge current situation is short circuit fault condition when being less than threshold value, if average equivalent inductance value more than one, average equivalent inductance
It is excitation surge current situation when value is all greater than equal to threshold value, is otherwise short circuit fault condition.
When the combined floodgate number of phases is a phase, the equivalent circuit of the breaker phase selection reclosing process, voltage
Equation is that combined floodgate phase voltage is equal to the sum of equivalent resistance pressure drop and equivalent inductance pressure drop；According to the combined floodgate at two neighbouring sample moment
Phase voltage and current data obtain two linear equations, calculate equivalent inductance；All equivalent inductances in sampling time are taken
Average value, obtain breaker one coincide lock when average equivalent inductance value.
If it is mutually A phases to close a floodgate, the coincide voltage equation of equivalent circuit of lock process of the breaker one is：
In formula, Req, LeqRespectively circuit equivalent resistance and equivalent inductance, iAFor A phase currents, uAFor A phase voltages.
When the combined floodgate number of phases is two-phase, the equivalent circuit of the breaker phase selection reclosing process, according to two
Phase current relationship is divided into two kinds of situations：
1) the sum of biphase current is not zero：The two-phase closed a floodgate in equivalent circuit constitutes two independent current loops, according to
Breaker one coincide lock when average equivalent calculating method of inductance calculate separately the average equivalent inductance value of combined floodgate phase；
2) the sum of biphase current is zero：It closes a floodgate in equivalent circuit and mutually only constitutes a current loop, with a wherein phase current
Positive direction as circuit positive direction, combined floodgate two-phase voltage difference is equal to equivalent resistance pressure drop and equivalent inductance pressure drop in equivalent circuit
The sum of；According to the two-phase voltage and loop current data at two neighbouring sample moment, two linear equations are obtained, are calculated equivalent
Inductance is averaged all equivalent inductances in the sampling time, obtains average equivalent inductance when breaker two-phase reclosing
Value.
When the combined floodgate number of phases is two-phase, if it is A, B two-phase to close a floodgate mutually, the sum of described biphase current is zero situation, etc.
Effect circuit voltage equation be：
In formula, uBFor B phase voltages.
When the combined floodgate number of phases is three-phase, the equivalent circuit of the breaker phase selection reclosing process, according to three
Phase current relationship is divided into two kinds of situations：
1) the sum of three-phase current is not zero：Three-phase constitutes three independent current loops in equivalent circuit, according to breaker
One coincide lock when average equivalent calculating method of inductance calculate separately the average equivalent inductance value of three-phase；
2) the sum of three-phase current is zero：Equivalent circuit is three branch circuit parallel connections, and every branch is a phase voltage source and the phase
Equivalent resistance and equivalent inductance series connection, choose two of which branch, are based on parallel branch voltage principle, establish voltage first
Equation；According to the two-phase voltage and current data of adjacent four sampling instants, four linear equations are obtained, calculate two-phase respectively
Equivalent resistance and equivalent inductance；The branch electricity at corresponding moment is acquired according to the wherein equivalent resistance of a phase and equivalent inductance value
Pressure, establishes the voltage equation of Article 3 branch；According to the voltage and current data of aforementioned four moment third phase, four lines are obtained
Property equation, the equivalent inductance is found out according to the computational methods of Least-squares Solution of Overdetermined Linear Equations；To the three-phase in the sampling time
Equivalent inductance is averaged respectively, obtains average equivalent inductance value when breaker three_phase reclosing.
When the combined floodgate number of phases is three-phase, the sum of described three-phase current is zero situation, the voltage of equivalent circuit
Equation is：
A, B two-phases：
C phases：
In formula, ReqA、ReqB、ReqCRespectively combined floodgate phase A, B, C equivalent resistance, LeqA、LeqB、LeqCRespectively combined floodgate phase A,
B, C equivalents inductance, iB、iCRespectively B, C phase current, uCRespectively C phase voltages, Un0For mains side neutral point potential, Un1For
Transformer primary side neutral point potential.
Within the scope of 3ms to 8ms, the average equivalent inductance threshold value is generally becoming the sampling time general control
It is chosen in 1/12 to 1/6 range of magnetizing inductance value obtained by depressor no-load test.
Advantageous effect：No-load transformer excitation surge current sentences during a kind of breaker phase selection reclosing provided by the invention
Other method has the advantages that compared with prior art：
The present invention is directed to the characteristics of transformer core equivalent inductance dynamic change, establishes the different combined floodgate numbers of phases and different transformations
Equivalent circuit when the device mode of connection and relevant voltage equation, solve the equivalent inductance of each sampling instant, its average value is taken to make
For no-load transformer excitation surge current criterion so that the no-load transformer excitation surge current situation energy during breaker phase selection reclosing
It is enough accurately identified, effectively improves fault identification accuracy rate and reclosing success rate.
Description of the drawings
Fig. 1 is magnetizing inrush current discrimination method schematic diagram of the present invention.
Fig. 2 is that YNy connections transformer one of the present invention coincides gate equivalent circuit schematic diagram.
Fig. 3 is that YNd connections transformer one of the present invention coincides gate equivalent circuit schematic diagram.
Fig. 4 is YNy connections transformer two-phase reclosing schematic equivalent circuit of the present invention.
Fig. 5 is Yy connections transformer two-phase reclosing schematic equivalent circuit of the present invention.
Fig. 6 is Dyn connections transformer two-phase reclosing schematic equivalent circuit of the present invention.
Fig. 7 is YNy connections Three-Phase Transformer reclosing schematic equivalent circuit of the present invention.
Fig. 8 is Yy connections Three-Phase Transformer reclosing schematic equivalent circuit of the present invention.
In figure：iA、iB、iCRespectively A, B, C phase current, uA、uB、uCRespectively A, B, C phase voltage, RA、RB、RCRespectively
Transformer primary side three-phase equivalent resistance, LA、LB、LCTransformer primary side three-phase equivalent inductance respectively, idWinding ring is connect for transformer d
Stream, Un0For mains side neutral point potential, Un1For transformer primary side neutral point potential.
Specific implementation mode
In the following with reference to the drawings and specific embodiments, the present invention is furture elucidated, it should be understood that these examples are merely to illustrate this
It invents rather than limits the scope of the invention, after having read the present invention, those skilled in the art are various to the present invention's
The modification of equivalent form falls within the application range as defined in the appended claims.
The method of discrimination of no-load transformer excitation surge current during the breaker phase selection reclosing of the present invention, when breaker selects
It coincides when overcurrent occurring during lock, is based on the combined floodgate number of phases and combined floodgate phase current feature, establishes equivalent circuit and corresponding electricity
Press equation；According to voltage, current sampling data, calculates the equivalent inductance value of each sampling instant and take its average value, this is averaged
Equivalent inductance value is as excitation surge current identical criterion.Method of discrimination schematic diagram thus shown in Fig. 1.
When the combined floodgate number of phases is a phase, the equivalent circuit of the breaker phase selection reclosing process, voltage
Equation is that combined floodgate phase voltage is equal to the sum of equivalent resistance pressure drop and equivalent inductance pressure drop.
If the combined floodgate mutually be A phases, the breaker one coincide lock equivalent circuit it is as shown in Figures 2 and 3, figure
Transformer is YNy connections in 2, and transformer is YNd connections in Fig. 3.
The coincide voltage equation of equivalent circuit of lock process of breaker one is：
In formula, Req, LeqRespectively circuit equivalent resistance and equivalent inductance.
Matrix equation is extracted according to the voltage equation：
According to voltage and current sample value, solution matrix equation calculates the equivalent inductance of corresponding sampling instant, to sampling
All equivalent inductances in time are averaged, obtain breaker one coincide lock when average equivalent inductance value.
When the combined floodgate number of phases is two-phase, the equivalent circuit of the breaker phase selection reclosing process, according to two
Phase current relationship is divided into two kinds of situations：
(1) the sum of biphase current is not zero.The two-phase closed a floodgate in equivalent circuit constitutes two independent current loops, according to
Breaker one coincide lock when average equivalent calculating method of inductance calculate separately the average equivalent inductance value of combined floodgate phase.Fig. 4 institutes
It is shown as equivalent circuit diagram when YNy connection transformer A, B two-phase reclosings, A, B two-phase constitute two independent current loops.
(2) the sum of biphase current is zero.It closes a floodgate in equivalent circuit and mutually only constitutes a current loop, with a wherein phase current
Positive direction as circuit positive direction, combined floodgate two-phase voltage difference is equal to equivalent resistance pressure drop and equivalent inductance pressure drop in equivalent circuit
The sum of.
Fig. 5 show equivalent circuit when Yy connection transformer A, B two-phase reclosings, and A, B two-phase constitute an electric current and returns
Road.Fig. 6 show equivalent circuit when Dyn connection transformer A, B two-phase reclosings, and A, B two-phase constitute a current loop.
A, the sum of B biphase currents are zero, and the voltage equation of equivalent circuit is：
Matrix equation is extracted according to the voltage equation：
According to voltage and current sample value, solution matrix equation calculates the equivalent inductance of corresponding sampling instant, to sampling
All equivalent inductances in time are averaged, and obtain average equivalent inductance value when breaker two-phase reclosing.
When the combined floodgate number of phases is three-phase, the equivalent circuit of the breaker phase selection reclosing process, according to three
Phase current relationship is divided into two kinds of situations：
(1) the sum of three-phase current is not zero：Three-phase constitutes three independent current loops in equivalent circuit, according to breaker
One coincide lock when average equivalent calculating method of inductance calculate separately the average equivalent inductance value of three-phase.Fig. 7 show YNy and connects
Equivalent circuit diagram when method Three-Phase Transformer reclosing, three-phase constitute three independent current loops.
(2) the sum of three-phase current is zero：Equivalent circuit is three branch circuit parallel connections, and every branch is a phase voltage source and the phase
Equivalent resistance and equivalent inductance series connection.Fig. 8 show equivalent circuit diagram when Yy connection Three-Phase Transformer reclosings, three-phase current
The sum of be zero.Three parallel branch voltages are equal：
In formula, ReqA、ReqB、ReqCRespectively combined floodgate phase A, B, C equivalent resistance, LeqA、LeqB、LeqCRespectively combined floodgate phase A,
B, C equivalents inductance.
It is arranged to obtain following voltage equation by the voltage relationship of A, B two-phase first：
Matrix equation is extracted according to A, B two-phase voltage equation：
According to the two-phase voltage and current data of adjacent four sampling instants, it is each to calculate A, B two-phase for solution matrix equation
From equivalent resistance and equivalent inductance.
The U at corresponding moment is acquired according to the wherein equivalent resistance of A phases and equivalent inductance valuen1-Un0Value, C phase voltage equations are whole
Reason is：
Matrix equation is extracted according to C phase voltage equations：
C equivalent inductance is found out according to the computational methods of Least-squares Solution of Overdetermined Linear Equations.To the three-phase in the sampling time
Equivalent inductance is averaged respectively, obtains average equivalent inductance value when breaker three_phase reclosing.
The sampling time general control is within the scope of 3ms to 8ms, and average equivalent inductance threshold value is generally in transformer sky
It carries and is chosen in 1/12 to 1/6 range of experiment gained magnetizing inductance value.Average equivalent inductance value and threshold value comparison will be acquired, will be more than
It is excitation surge current situation when equal to threshold value, is short circuit fault condition when being less than threshold value.If average equivalent inductance value more than one,
It is excitation surge current situation when average equivalent inductance value is all greater than equal to threshold value, is otherwise short circuit fault condition.
The present invention is directed to the characteristics of transformer core equivalent inductance dynamic change, establishes the different combined floodgate numbers of phases and different transformations
Equivalent circuit when the device mode of connection and relevant voltage equation, solve the equivalent inductance of each sampling instant, its average value is taken to make
For no-load transformer excitation surge current criterion so that the no-load transformer excitation surge current situation energy during breaker phase selection reclosing
It is enough accurately identified, effectively improves fault identification accuracy rate and reclosing success rate.
The above is only a preferred embodiment of the present invention, it should be pointed out that：For the ordinary skill people of the art
For member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also answered
It is considered as protection scope of the present invention.
Claims (8)
1. the method for discrimination of no-load transformer excitation surge current during a kind of breaker phase selection reclosing, which is characterized in that the party
Method includes the following steps：When overcurrent occurring during breaker phase selection reclosing, it is based on the combined floodgate number of phases and combined floodgate phase current
Feature establishes equivalent circuit and relevant voltage equation；According to voltage, current sampling data, the equivalent electricity of each sampling instant is calculated
Inductance value simultaneously takes its average value；By average equivalent inductance value and threshold value comparison, it is excitation surge current situation when being more than or equal to threshold value, is less than
It is short circuit fault condition when threshold value, if average equivalent inductance value more than one, average equivalent inductance value is all greater than equal to threshold
It is excitation surge current situation when value, is otherwise short circuit fault condition.
2. the method for discrimination of no-load transformer excitation surge current during breaker phase selection reclosing according to claim 1,
It is characterized in that, when the combined floodgate number of phases is a phase, the equivalent circuit of the breaker phase selection reclosing process, electricity
It is that combined floodgate phase voltage is equal to the sum of equivalent resistance pressure drop and equivalent inductance pressure drop to press equation；According to the conjunction at two neighbouring sample moment
Lock phase voltage and current data obtain two linear equations, calculate equivalent inductance；To all equivalent inductances in the sampling time
Be averaged, obtain breaker one coincide lock when average equivalent inductance value.
3. the method for discrimination of no-load transformer excitation surge current during breaker phase selection reclosing according to claim 2,
It is characterized in that, set combined floodgate mutually as A phases, the coincide voltage equation of equivalent circuit of lock process of the breaker one is：
In formula, Req, LeqRespectively circuit equivalent resistance and equivalent inductance, iAFor A phase currents, uAFor A phase voltages.
4. the method for discrimination of no-load transformer excitation surge current during breaker phase selection reclosing according to claim 1,
It is characterized in that, when the combined floodgate number of phases is two-phase, the equivalent circuit of the breaker phase selection reclosing process, according to
Biphase current relationship is divided into two kinds of situations：
1) the sum of biphase current is not zero：The two-phase closed a floodgate in equivalent circuit constitutes two independent current loops, according to open circuit
Device one coincide lock when average equivalent calculating method of inductance calculate separately the average equivalent inductance value of combined floodgate phase；
2) the sum of biphase current is zero：It closes a floodgate in equivalent circuit and mutually only constitutes a current loop, just with a wherein phase current
Direction as circuit positive direction, in equivalent circuit combined floodgate two-phase voltage difference be equal to equivalent resistance pressure drop and equivalent inductance pressure drop it
With；According to the two-phase voltage and loop current data at two neighbouring sample moment, two linear equations are obtained, equivalent electricity is calculated
Sense, is averaged all equivalent inductances in the sampling time, obtains average equivalent inductance value when breaker two-phase reclosing.
5. the method for discrimination of no-load transformer excitation surge current during breaker phase selection reclosing according to claim 4,
It is characterized in that, when the combined floodgate number of phases is two-phase, if it is A, B two-phase to close a floodgate mutually, the sum of described biphase current is zero
The voltage equation of situation, equivalent circuit is：
In formula, uBFor B phase voltages.
6. the method for discrimination of no-load transformer excitation surge current during breaker phase selection reclosing according to claim 1,
It is characterized in that, when the combined floodgate number of phases is three-phase, the equivalent circuit of the breaker phase selection reclosing process, according to
Three-phase current relationship is divided into two kinds of situations：
1) the sum of three-phase current is not zero：Three-phase constitutes three independent current loops in equivalent circuit, according to one phase of breaker
Average equivalent calculating method of inductance when reclosing calculates separately the average equivalent inductance value of three-phase；
2) the sum of three-phase current is zero：Equivalent circuit is three branch circuit parallel connections, and every branch is a phase voltage source and the equivalent
Resistance and equivalent inductance series connection, choose two of which branch, are based on parallel branch voltage principle, establish voltage side first
Journey；According to the two-phase voltage and current data of adjacent four sampling instants, four linear equations are obtained, it is respective to calculate two-phase
Equivalent resistance and equivalent inductance；The branch voltage at corresponding moment is acquired according to the wherein equivalent resistance of a phase and equivalent inductance value,
Establish the voltage equation of Article 3 branch；According to the voltage and current data of aforementioned four moment third phase, four are obtained linearly
Equation finds out the equivalent inductance according to the computational methods of Least-squares Solution of Overdetermined Linear Equations；It is equal to three in the sampling time
Effect inductance is averaged respectively, obtains average equivalent inductance value when breaker three_phase reclosing.
7. the method for discrimination of no-load transformer excitation surge current during breaker phase selection reclosing according to claim 6,
It is characterized in that, when the combined floodgate number of phases is three-phase, the sum of described three-phase current is zero situation, the electricity of equivalent circuit
Pressure equation be：
A, B two-phases：
C phases：
In formula, ReqA、ReqB、ReqCRespectively combined floodgate phase A, B, C equivalent resistance, LeqA、LeqB、LeqCRespectively combined floodgate phase A, B, C
Equivalent inductance, iB、iCRespectively B, C phase current, uCFor C phase voltages, Un0For mains side neutral point potential, Un1For transformer primary
Side neutral point potential.
8. the differentiation of no-load transformer excitation surge current during the breaker phase selection reclosing according to claim 2,4 or 6
Method, which is characterized in that the sampling time general control is within the scope of 3ms to 8ms, the average equivalent inductance threshold value
Generally chosen in 1/12 to 1/6 range of the magnetizing inductance value obtained by No-load Test of Transformer.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810393999.9A CN108429229B (en) | 2018-04-27 | 2018-04-27 | Method for judging excitation inrush current of no-load transformer in phase selection reclosing process of circuit breaker |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810393999.9A CN108429229B (en) | 2018-04-27 | 2018-04-27 | Method for judging excitation inrush current of no-load transformer in phase selection reclosing process of circuit breaker |
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| CN108429229A true CN108429229A (en) | 2018-08-21 |
| CN108429229B CN108429229B (en) | 2020-02-21 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109217268A (en) * | 2018-09-20 | 2019-01-15 | 罗孚电气（厦门）有限公司 | Intelligent breaker guard method and device based on sampled value |
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|---|---|---|---|---|
| CN1303156A (en) * | 2001-01-22 | 2001-07-11 | 南京南瑞继保电气有限公司 | Relay protection method based on excitation impedance variation to judge excitating surge current of transformer |
| CN102879671A (en) * | 2012-09-17 | 2013-01-16 | 华北电力大学 | Method for judging inrush current locking of equivalent instantaneous inductance for protection of extra-high voltage regulating transformer |
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2018
- 2018-04-27 CN CN201810393999.9A patent/CN108429229B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1303156A (en) * | 2001-01-22 | 2001-07-11 | 南京南瑞继保电气有限公司 | Relay protection method based on excitation impedance variation to judge excitating surge current of transformer |
| CN102879671A (en) * | 2012-09-17 | 2013-01-16 | 华北电力大学 | Method for judging inrush current locking of equivalent instantaneous inductance for protection of extra-high voltage regulating transformer |
Non-Patent Citations (1)
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| 葛宝明等: "基于等效瞬时电感判别变压器励磁涌流的新算法", 《电力***自动化》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109217268A (en) * | 2018-09-20 | 2019-01-15 | 罗孚电气（厦门）有限公司 | Intelligent breaker guard method and device based on sampled value |
| CN109217268B (en) * | 2018-09-20 | 2020-04-07 | 罗孚电气（厦门）有限公司 | Intelligent circuit breaker protection method and device based on sampling value |
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