CN105977914B - The method and device of transformer zero-sequencedirectional protection under interior bridge mode - Google Patents
The method and device of transformer zero-sequencedirectional protection under interior bridge mode Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
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Abstract
The invention discloses a kind of method and devices of transformer zero-sequencedirectional protection under interior bridge mode.Wherein, method includes：The zero-sequence current of enter line side current transformer, the zero-sequence current of Nei Qiao sides current transformer and the vector sum of the two are obtained respectively；If above-mentioned three is any to be more than rotection thresholds, the breaker between transformer and inlet wire is disconnected.Technical solution provided in an embodiment of the present invention solves the problems, such as that the sensitivity of traditional zero-sequencedirectional protection method is low.
Description
Technical field
The present invention relates to transformer zero sequence overcurrents under microcomputer type relay protection technical field more particularly to a kind of interior bridge mode
The method and device of protection.
Background technology
Transformer is the important equipment of electric system, once it breaks down, it will be to the normal power supply and equipment safety of system
Serious influence is brought, and tranformer protection is the important defence line of its reliable after breaking down, timely isolated fault point.After
In " four property " of electric protection, sensitivity refers to protective relaying device to the failure or irregular operating shape that occur in its protection domain
The respond of state, sensitivity are weighed with sensitivity coefficient.Wherein the minimum of fault parameter, calculated maximum are according to actually may be used
Can the least favorable method of operation, fault type and short dot calculate.The size of sensitivity coefficient determines protects when failure occurs
Shield whether can action message, thus be weigh protection important indicator.
In tranformer protection, high-pressure side winding when zero-sequencedirectional protection is directly grounded operation as transformer neutral point,
The back-up protection of high-pressure side lead-out wire and busbar grounding failure and the back-up protection of adjacent power line-to-ground fault.Work as power transformation
It stands when using internal bridge connection (mainly 110kV substations), since high voltage side of transformer does not install current transformer TA, because
And the logical operation for using the measured value of enter line side TA and Nei Qiao side TA that vector sum is taken to participate in high voltage side of transformer back-up protection.This
When zero-sequencedirectional protection is using self-produced zero stream, i.e., " high-pressure side zero sequence overcurrent using self-produced zero stream " control word in tranformer protection
When putting 1, traditional self-produced zero-sequencedirectional protection is using self-produced zero streams of enter line side TA and self-produced zero flow vectors of Nei Qiao sides TA and conduct
Criterion.
However analysis shows, under three kinds of methods of operation being likely to occur in interior bridging power station, when outside Nei He areas of transformer area
When electrically earth fault occurs for (at the K1 of such as Fig. 2 and the K2 of Fig. 3 places) at very similar two, zero sequence overcurrent guarantor in traditional criterion
The sensitivity of shield considerably reduces.
Invention content
In view of this, the embodiment of the present invention provides the method and dress of transformer zero-sequencedirectional protection under a kind of interior bridge mode
It puts, to solve the problems, such as that the sensitivity of traditional zero-sequencedirectional protection method is low.
In a first aspect, an embodiment of the present invention provides a kind of method of transformer zero-sequencedirectional protection under interior bridge mode, packet
It includes：
The zero-sequence current of enter line side current transformer, the zero-sequence current and two of Nei Qiao sides current transformer are obtained respectively
The vector sum of person；
If above-mentioned three is any to be more than rotection thresholds, the breaker between transformer and inlet wire is disconnected.
Second aspect, an embodiment of the present invention provides a kind of device of transformer zero-sequencedirectional protection under interior bridge mode, packets
Include transformer, enter line side current transformer, Nei Qiao sides current transformer and the breaker of internal bridge, which is characterized in that also wrap
It includes：
Zero-sequence current acquisition module, for obtaining the zero-sequence current of the enter line side current transformer, the interior bridge respectively
The zero-sequence current of side current transformer and the vector sum of the two；
Overcurrent protection action module, for above-mentioned three it is any be more than rotection thresholds when, disconnect the transformer with into
The breaker between line.
The method and device of transformer zero-sequencedirectional protection under a kind of interior bridge mode provided in an embodiment of the present invention, by dividing
Not Huo Qu enter line side current transformer zero-sequence current, the zero-sequence current of Nei Qiao sides current transformer and the vector sum of the two,
Above-mentioned three is formed or door operation, then above-mentioned three is any when being more than rotection thresholds, disconnects disconnected between transformer and inlet wire
Road device, this programme, only with self-produced zero flow vector of both sides current transformer and the method as criterion, are avoided relative to existing
During transformer external short-circuit failure, the problem of zero-sequencedirectional protection sensitivity is poor, transformer zero-sequencedirectional protection is improved
Sensitivity makes protection action message.
Description of the drawings
By reading the detailed description made to non-limiting example made with reference to the following drawings, of the invention is other
Feature, objects and advantages will become more apparent upon：
Fig. 1 is the method flow of transformer zero-sequencedirectional protection under a kind of interior bridge mode that the embodiment of the present invention one provides
Figure；
Fig. 2 is singlephase earth fault figure in 2 times transformer areas of the method for operation of the offer of the embodiment of the present invention one；
Fig. 3 is singlephase earth fault figure outside 2 times transformer areas of the method for operation of the offer of the embodiment of the present invention one；
Fig. 4 is singlephase earth fault sequence diagrams in 2 times transformer areas of the method for operation provided by Embodiment 2 of the present invention；
Fig. 5 is singlephase earth fault sequence diagrams outside 2 times transformer areas of the method for operation provided by Embodiment 2 of the present invention；
Fig. 6 is singlephase earth fault figure in 3 times transformer areas of the method for operation of the offer of the embodiment of the present invention three；
Fig. 7 is singlephase earth fault figure outside 3 times transformer areas of the method for operation of the offer of the embodiment of the present invention three；
Fig. 8 is singlephase earth fault sequence diagrams in 3 times transformer areas of the method for operation of the offer of the embodiment of the present invention three；
Fig. 9 is singlephase earth fault sequence diagrams outside 3 times transformer areas of the method for operation of the offer of the embodiment of the present invention three；
Figure 10 is the apparatus structure of transformer zero-sequencedirectional protection under a kind of interior bridge mode that the embodiment of the present invention four provides
Figure.
Specific embodiment
The present invention is described in further detail with reference to the accompanying drawings and examples.It is understood that this place is retouched
The specific embodiment stated is used only for explaining the present invention rather than limitation of the invention.It also should be noted that in order to just
Part related to the present invention rather than full content are illustrated only in description, attached drawing.
It also should be noted that illustrate only for ease of description, in attached drawing part related to the present invention rather than
Full content.It should be mentioned that some exemplary embodiments are described before exemplary embodiment is discussed in greater detail
Into the processing or method described as flow chart.Although operations (or step) are described as the processing of sequence by flow chart,
It is that many of which operation can be implemented concurrently, concomitantly or simultaneously.In addition, the sequence of operations can be by again
It arranges.The processing can be terminated when its operations are completed, it is also possible to have the additional step being not included in attached drawing.
The processing can correspond to method, function, regulation, subroutine, subprogram etc..
Embodiment one
Fig. 1 is the method flow of transformer zero-sequencedirectional protection under a kind of interior bridge mode that the embodiment of the present invention one provides
Figure.The method of the present embodiment can be performed by the device of transformer zero-sequencedirectional protection under interior bridge mode, and described device can pass through
The mode of software and/or hardware is realized.As shown in Figure 1, transformer zero-sequencedirectional protection under interior bridge mode provided in this embodiment
Method specifically include：
S110, the zero-sequence current for obtaining enter line side current transformer respectively, the zero-sequence current of Nei Qiao sides current transformer, with
And the vector sum of the two.
If S120, above-mentioned three are any more than rotection thresholds, the breaker between transformer and inlet wire is disconnected.
Internal bridge and outer bridging line are only applicable to the wiring of two transformers, two inlet wires.Interior bridge mode exists for mother
The inside of two transformer switches, close to transformer side.Outer bridge mode is mother in the outside of two transformer switches, close into
Line side.The interior bridge mode for needing to consider tranformer protection, referring to figs. 2 and 3, two the first inlet wires of inlet wire are introduced in the present embodiment
1 and second inlet wire 2 be connected separately with the first transformer 3 and the second transformer 4, busbar is located at the interior of two breakers 1DL and 2DL
Side, close to transformer side.Enter line side current transformer TA1 and TA2 are installed on internal bridge enter line side, for acquiring enter line side three
Phase current, Nei Qiao sides current transformer TA3 are installed on internal bridge Nei Qiao sides, for acquiring Nei Qiao sides three-phase current.
When single-phase or two-phase ground short circuit failure occurs for any point in electric system, zero sequence electricity will be generated in system
Stream.At this point, will appear a residual voltage in earth fault, zero-sequence current will be generated under the effect of this voltage.
There was only forward-order current during system normal operation, negative-sequence current and zero sequence electricity are just generated when there is unbalanced fault
Stream, i.e., negative-sequence current and zero-sequence current are generated by trouble point.The short circuit path of positive and negative sequence is closed by short dot to electric power generating composition
Circuit is closed, zero sequence short circuit path forms closed circuit by short circuit grounding point to transformer grounding point.
In the present embodiment, the high-pressure side of the transformer is star-connection, the neutral-point solid ground of the star-connection.
If high-pressure side is delta connection, without zero-sequence current, therefore setting zero-sequencedirectional protection is not needed to；If star-star connection,
But isolated neutral, zero-sequence current is little, need not also set zero-sequencedirectional protection；If star-star connection, and neutral point
It is directly grounded, then has zero-sequence current, if having reached high-pressure side protection act value, start zero-sequencedirectional protection.If transformer is
High-pressure side star-connection, low-pressure side delta connection, with reference to figure 2 or Fig. 3, then zero-sequence current component is filtered in delta connection side
It removes, low-pressure side no longer has zero-sequence current.
It is noted that the zero-sequence current is preferably self-produced zero stream.Self-produced zero stream is by passing through inside protective device
Three-phase current vector is formed by stacking by logic circuit or program calculating, and external zero-sequence current is to be synthesized by current transformer or special
What zero sequence current mutual inductor was directly formed.In practical application, due to external zero sequence current mutual inductor polarity may wrong, be
Ensure the correctness of zero sequence direction, the zero sequence direction of protective device can use self-produced residual voltage and self-produced zero-sequence current.This
In scheme, the three-phase current of enter line side current transformer and Nei Qiao sides current transformer is obtained respectively first, inside protective device
Three-phase current vector is superimposed, obtains self-produced zero stream of enter line side current transformer and Nei Qiao sides current transformer.By the two
Self-produced zero stream does vector sum, then obtained enter line side current transformer it is self-produced zero stream, Nei Qiao sides current transformer self-produced zero
The vector sum of stream and the two.
Internal bridge connection is commonly available to 110kV substations, and typical wiring figure has one as shown in Fig. 2, arrangement is simple
Fixed reliability and flexibility, low cost few using equipment.Arrangement is suitable.It has the following characteristics that：Suitable for circuit it is longer,
Transformer is not required to the situation often switched；Line fault does not influence transformer normal operation, and the switching of transformer can cause circuit
Exit work；Suitable for the main connection mode design of electric substation of the penetration less or almost without penetration.
For 110kV internal bridge connections, there are following several methods of operation：
The method of operation 1,2 fanout operation of the first inlet wire 1 and the second inlet wire；
The method of operation 2, it is spare that the second inlet wire of the first inlet wire 1 operation 2 is spare, the second inlet wire 2 runs the first inlet wire 1；
The method of operation 3, two inlet wires are run with interior bridge, suitable for there is situation during penetration.
For the method for operation 1, because the first inlet wire 1 and 2 fanout operation of the second inlet wire are not related to point outside Nei He areas of area, zero
Sequence overcurrent protection is protected with conventional transformer, therefore the embodiment of the present invention does not repeat it.
Transformer zero-sequencedirectional protection method under existing interior bridge mode, by using self-produced zero stream of enter line side and Nei Qiao sides
Self-produced zero flow vector and composition logical operation are applied to zero-sequencedirectional protection.But for singlephase earth fault, transformer area
Outside Nei Huo areas during single-phase earthing, the direction for flowing through the zero-sequence current of busbar is opposite.
Referring to figs. 2 and 3, Fig. 2 and Fig. 3 is respectively the failure being unidirectionally grounded outside Nei He areas of 2 times transformer areas of the method for operation
Figure, the first inlet wire 1 is run at this time, and the second inlet wire 2 is spare.In Fig. 2, zero-sequence current divides three parts 3I by short dot K110、3I20
And 3I30The earth point of the first inlet wire 1, the earth point of the second transformer 4 and the first transformer 3 is flowed to respectively, wherein, zero-sequence current
3I20It is right by left flow direction in figure.In Fig. 3, zero-sequence current is divided into two parts 3I by short dot K220And 3I40Left side branch is flowed to respectively
Road and the earth point of the second transformer 4.3I20After flowing to left side branch, it is divided into two parts 3I10And 3I30The first inlet wire is flowed to respectively
1 and first transformer 3 earth point.3I is obtained by Fig. 2 and Fig. 320In above-mentioned two situations, current direction is opposite.Therefore
Only choose 3I10And 3I20Vector sum to be used as the criterion of overcurrent protection be inaccurate, outside area during singlephase earth fault, spirit
Sensitivity can be decreased obviously.The present embodiment acquires the zero-sequence current 3I of enter line side current transformer TA1 respectively10, Nei Qiao sides electric current is mutual
The zero-sequence current 3I of sensor TA320And criterion of the vector sum of the two as zero-sequenceprotection, when any one value is more than protection threshold
During value, start zero-sequencedirectional protection, disconnect the breaker between transformer and inlet wire, increase the sensitive of zero-sequencedirectional protection
Degree.Here breaker refers to being currently under closed state, and connects the open circuit of the inlet wire in work and transformer
Device, for example, breaker 1DL and 3DL in Fig. 2 or Fig. 3.
The embodiment of the present invention one provide interior bridge mode under transformer zero-sequencedirectional protection method, by obtain respectively into
The zero-sequence current of line side current transformer, the zero-sequence current of Nei Qiao sides current transformer and the vector sum of the two, by above-mentioned three
Person form or door operation, then above-mentioned three it is any be more than rotection thresholds when, start zero-sequencedirectional protection, this programme is relative to existing
Only with self-produced zero flow vector of both sides current transformer and the method as criterion, avoid transformer external short-circuit failure
When, the problem of zero-sequencedirectional protection sensitivity is poor, the sensitivity of transformer zero-sequencedirectional protection is improved, protection is made reliably to move
Make.
Embodiment two
The embodiment of the present invention is on the basis of embodiment one, to the transformer under bridge mode interior in embodiment one in operation side
In the case of formula 2, zero-sequence protection method is analyzed during singlephase earth fault outside Nei He areas of area.
Since the first inlet wire 1 is run, the second inlet wire 2 is spare and the second inlet wire 2 is run, 1 standby mode principle of the first inlet wire
It is identical.The present embodiment is run with the first inlet wire 1, is analyzed for the second inlet wire 2 is spare, shown referring to figs. 2 and 3.
As shown in Fig. 2, when singlephase earth fault (at the K1 of high-pressure side) in 3rd area of the first transformer, failure sequence diagrams are such as
Shown in Fig. 4, it is assumed that singlephase earth fault is mutually A phases, IKA1For A phase forward-order currents, IKA2For A phase negative-sequence currents, IKA0For A phase zeros
Sequence electric current.Likewise, UKA1、UKA2And UKA0The respectively positive sequence of A phases, negative phase-sequence and residual voltage.When A phases are grounded, IKA1=IKA2
=IKA3, UKA1+UKA2+UKA0=0.With reference to figure 4, Xs1、Xs2And Xs0Respectively system positive sequence, negative phase-sequence and zero-sequence reactance, XT10And XT20
The zero sequence impedance of the first transformer 3 and the second transformer 4 is represented respectively.Then self-produced zero stream of enter line side current transformer TA1
3I10, Nei Qiao sides current transformer TA3 zero-sequence current 3I20And the two vector sum is respectively：
As shown in figure 3, when A phases earth fault (at K2) in 3rd area of the first transformer, failure sequence diagrams are as shown in Figure 5.
The then self-produced zero stream 3I of enter line side current transformer TA110, Nei Qiao sides current transformer TA3 zero-sequence current 3I20And the two arrow
It measures and is respectively：
It is now calculated, made the following assumptions according to real data：
1st, consider 110kV system short-circuit levels between 5kA~35kA.
2nd, reference capacity 100MVA, reference voltage 110kV are chosen.
3rd, the zero sequence impedance of system is 3 times of positive sequence impedance.
4th, two systems divide equally short circuit current, and corresponding sequence impedance is equal.
5th, 110kV Transformer Short Circuit Impedances percentage is 10.5%, capacity 50MVA.
6th, two transformer parameters are consistent.
Can show under the method for operation 2 that different short circuit currents correspond to each impedance perunit value by data above, perunit value it is specific
Numerical value is as shown in table 1.
Table 1
| Short circuit current (KA) | Xs1 | Xs2 | Xs0 | XT10 | XT20 |
| 35 | 0.015 | 0.015 | 0.045 | 0.21 | 0.21 |
| 25 | 0.021 | 0.021 | 0.063 | 0.21 | 0.21 |
| 20 | 0.026 | 0.026 | 0.079 | 0.21 | 0.21 |
| 15 | 0.035 | 0.035 | 0.105 | 0.21 | 0.21 |
| 10 | 0.0525 | 0.0525 | 0.1575 | 0.21 | 0.21 |
| 5 | 0.105 | 0.105 | 0.315 | 0.21 | 0.21 |
It is mutual to combine formula (1)~(3) can be calculated enter line side electric current by table 1 for singlephase earth fault at 2 times K1 of the method for operation
The self-produced zero stream 3I of sensor TA110, Nei Qiao sides current transformer TA3 it is self-produced zero stream 3I20And the two vector sum, as shown in table 2.
Table 2
| Short circuit current (KA) | 3I10 | 3I20 | 3I10+3I20 |
| 35 | 0.7I0 | 0.15I0 | 0.85I0 |
| 25 | 0.62I0 | 0.19I0 | 0.81I0 |
| 20 | 0.57I0 | 0.21I0 | 0.78I0 |
| 15 | 0.5I0 | 0.25I0 | 0.75I0 |
| 10 | 0.4I0 | 0.3I0 | 0.7I0 |
| 5 | 0.25I0 | 0.375I0 | 0.625I0 |
It is mutual to combine formula (4)~(6) can be calculated enter line side electric current by table 1 for singlephase earth fault at 2 times K2 of the method for operation
The self-produced zero stream 3I of sensor TA110, Nei Qiao sides current transformer TA3 it is self-produced zero stream 3I20And the two vector sum, as shown in table 3.
Table 3
| Short circuit current (KA) | 3I10 | 3I20 | 3I10+3I20 |
| 35 | 0.7I0 | 0.85I0 | 0.15I0 |
| 25 | 0.62I0 | 0.81I0 | 0.19I0 |
| 20 | 0.57I0 | 0.78I0 | 0.21I0 |
| 15 | 0.5I0 | 0.75I0 | 0.25I0 |
| 10 | 0.4I0 | 0.7I0 | 0.3I0 |
| 5 | 0.25I0 | 0.625I0 | 0.375I0 |
For table 2, at K1 during singlephase earth fault, because of the self-produced zero stream 3I of enter line side current transformer TA110With interior bridge
The self-produced zero stream 3I of side current transformer TA320Vector sum be more than any of which value, so using its vector sum come with rotection thresholds
It is compared, when its vector sum is more than rotection thresholds, triggers zero-sequencedirectional protection circuit.It can be sentenced using sensitivity coefficient Klm
The sensitivity of disconnected method.The ratio of fault current and rotection thresholds when sensitivity coefficient is action is sensitive in certain range
Coefficient is higher, and sensitivity is stronger.For example, rotection thresholds are set as 0.1I0, when short circuit current is 35KV, Klm=0.85I0/
0.1I0=8.5.It is identical with the sensitivity of the calculating of this embodiment scheme using conventional method at K1 during singlephase earth fault.
For table 3, at K2 during singlephase earth fault, the self-produced zero stream 3I of enter line side current transformer TA110With Nei Qiao sides electricity
The self-produced zero stream 3I of current transformer TA320Vector sum compare 3I20It is small, because of 3I at this time20Direction changed.Use vector sum
Judged, sensitivity is poor.For example, setting rotection thresholds are similarly 0.1I0, with vector sum compared with rotection thresholds, acquire
Sensitivity coefficient Klm=0.15I0/0.1I0=1.5, this embodiment scheme first obtains 3I10=0.7I0, 3I20=0.85I0And 3I10+
3I20=0.15I0, obtain maximum value 3I therein20=0.85I0, so sensitivity coefficient Klm=0.85I0/0.1I0=8.5.Institute
It is 1.5 to obtain sensitivity coefficient in the conventional way, and this programme sensitivity coefficient is 8.5, and the sensitivity of zero-sequencedirectional protection method obtains
It improves.
The present embodiment two in the case of the method for operation 2, connects the transformer under interior bridge mode to single-phase outside Nei He areas of area
Earth fault situation is compared, and traditional method is compared with this programme, as a result obtains this programme for single-phase outside area
Earth fault, sensitivity is greatly improved compared with traditional method.
Embodiment three
Fig. 6 is singlephase earth fault figure in 3 times transformer areas of the method for operation of the offer of the embodiment of the present invention three.Fig. 7 is this
Singlephase earth fault figure outside 3 times transformer areas of the method for operation that inventive embodiments three provide.The embodiment of the present invention is in embodiment one
On the basis of embodiment two, to transformer in embodiment one in the case of the method for operation 3, single-phase earthing event outside Nei He areas of area
Zero-sequence protection method is analyzed during barrier.
Two inlet wires are run with interior bridge in the method for operation 3, and with reference to figure 6, i.e. breaker 1DL, 2DL and 3DL is closed, interior
There is certain penetration on bridge.As the self-produced zero stream 3I of enter line side current transformer TA110, Nei Qiao sides current transformer TA3
Zero-sequence current 3I20And in the two vector sum, there is one to be more than rotection thresholds, then cut-off breaker 1DL, 2DL and 3DL.Because two
Inlet wire is run simultaneously, is leading the first system and with the with the first inlet wire 1 so there are two systems under this method of operation
Two inlet wires 2 are leading second system.
As shown in fig. 6, at K1 during singlephase earth fault, it is also assumed that A phases are grounded, failure sequence network figure such as Fig. 8 institutes
Show.Wherein Xs11、Xs12And Xs10For the first system positive sequence, negative phase-sequence and zero-sequence reactance, Xs21、Xs22And Xs20For second system positive sequence,
Negative phase-sequence and zero-sequence reactance, XT10、XT20The zero sequence impedance of first transformer 3 and the second transformer 4 respectively.Enter line side current transformer
The self-produced zero stream 3I of TA110, Nei Qiao sides current transformer TA3 zero-sequence current 3I20And the two vector sum is respectively：
As shown in fig. 7, at K2 during singlephase earth fault, failure sequence network figure is as shown in Figure 9.Enter line side Current Mutual Inductance
The self-produced zero stream 3I of device TA110, Nei Qiao sides current transformer TA3 zero-sequence current 3I20And the two vector sum is respectively：
The hypothesis that the present embodiment real data is made is the same as above-described embodiment two.It can obtain different short circuit electricity under the method for operation 3
Road corresponds to each impedance perunit value, and the concrete numerical value of perunit value is as shown in table 4.
Table 4
| Short circuit current (KA) | Xs11 | Xs12 | Xs10 | Xs21 | Xs22 | Xs20 | XT10 | XT20 |
| 35 | 0.03 | 0.03 | 0.09 | 0.03 | 0.03 | 0.09 | 0.21 | 0.21 |
| 25 | 0.042 | 0.042 | 0.126 | 0.042 | 0.042 | 0.126 | 0.21 | 0.21 |
| 20 | 0.052 | 0.052 | 0.158 | 0.052 | 0.052 | 0.158 | 0.21 | 0.21 |
| 15 | 0.07 | 0.07 | 0.21 | 0.07 | 0.07 | 0.21 | 0.21 | 0.21 |
| 10 | 0.105 | 0.105 | 0.315 | 0.105 | 0.105 | 0.315 | 0.21 | 0.21 |
| 5 | 0.21 | 0.21 | 0.63 | 0.21 | 0.21 | 0.63 | 0.21 | 0.21 |
It is mutual to combine formula (7)~(9) can be calculated enter line side electric current by table 4 for singlephase earth fault at 3 times K1 of the method for operation
The self-produced zero stream 3I of sensor TA110, Nei Qiao sides current transformer TA3 it is self-produced zero stream 3I20And the two vector sum, as shown in table 5.
Table 5
| Short circuit current (KA) | 3I10 | 3I20 | 3I10+3I20 |
| 35 | 0.35I′0 | 0.5I′0 | 0.85I′0 |
| 25 | 0.31I′0 | 0.5I′0 | 0.81I′0 |
| 20 | 0.29I′0 | 0.5I′0 | 0.79I′0 |
| 15 | 0.25I′0 | 0.5I′0 | 0.75I′0 |
| 10 | 0.2I′0 | 0.5I′0 | 0.7I′0 |
| 5 | 0.125I′0 | 0.5I′0 | 0.625I′0 |
Singlephase earth fault at 3 times K2 of the method for operation combines formula (10)~(12) by table 4 and can be calculated enter line side electric current
The self-produced zero stream 3I of mutual inductor TA110, Nei Qiao sides current transformer TA3 it is self-produced zero stream 3I20And the two vector sum, as shown in table 6.
Table 6
| Short circuit current (KA) | 3I10 | 3I20 | 3I10+3I20 |
| 35 | 0.35I′0 | 0.5I′0 | 0.15I′0 |
| 25 | 0.315I′0 | 0.5I′0 | 0.185I′0 |
| 20 | 0.285I′0 | 0.5I′0 | 0.215I′0 |
| 15 | 0.25I′0 | 0.5I′0 | 0.25I′0 |
| 10 | 0.2I′0 | 0.5I′0 | 0.3I′0 |
| 5 | 0.125I′0 | 0.5I′0 | 0.375I′0 |
Likewise, for table 5, at K1 during singlephase earth fault, because of self-produced zero streams of enter line side current transformer TA1
3I10Zero stream 3I self-produced with Nei Qiao sides current transformer TA320Vector sum be more than any of which value, the scheme of the present embodiment becoming
Sensitivity in depressor area during single-phase earthing with traditional scheme is the same.For example, rotection thresholds are set as 0.1I '0, work as short circuit current
During for 35KV, the sensitivity coefficient of conventional method and this programme is all Klm=0.85I '0/0.1I′0=8.5.
For table 6, at K2 during singlephase earth fault, the self-produced zero stream 3I of enter line side current transformer TA110With Nei Qiao sides electricity
The self-produced zero stream 3I of current transformer TA320Vector sum compare 3I20It is small.Sensitivity is then deteriorated when being judged using vector sum.Example
Such as, setting rotection thresholds are similarly 0.1I '0, with vector sum compared with rotection thresholds, acquire sensitivity coefficient Klm=0.15I '0/
0.1I′0=1.5, this embodiment scheme first obtains 3I10=0.35I '0, 3I20=0.5I '0And 3I10+3I20=0.15I '0, obtain
Maximum value 3I therein20=0.5I '0, so sensitivity coefficient Klm=0.5I '0/0.1I′0=5.It obtains in the conventional way sensitive
Coefficient is 1.5, and this method sensitivity coefficient is 5, and the sensitivity of zero-sequencedirectional protection method is improved.
The embodiment of the present invention three to transformer in the case of the method for operation 3, to singlephase earth fault feelings outside Nei He areas of area
Condition is compared, and traditional method is compared with this programme, as a result equally obtains this programme for single-phase earthing outside area
Failure, sensitivity is greatly improved compared with traditional method.
Example IV
Figure 10 is the apparatus structure of transformer zero-sequencedirectional protection under a kind of interior bridge mode that the embodiment of the present invention four provides
Figure.As shown in Figure 10, the transformer 101 including internal bridge, enter line side current transformer 102, Nei Qiao sides current transformer 103
With breaker 104, which is characterized in that further include：
Zero-sequence current acquisition module 105, for obtaining the zero-sequence current of enter line side current transformer 102, Nei Qiao sides respectively
The zero-sequence current of current transformer 103 and the vector sum of the two；
Overcurrent protection action module 106, for above-mentioned three it is any be more than rotection thresholds when, disconnect transformer 101 with
Breaker 104 between inlet wire.
Further, enter line side current transformer 102 is installed on internal bridge enter line side, for acquiring enter line side three-phase electricity
Stream；Nei Qiao sides current transformer 103 is installed on internal bridge Nei Qiao sides, for acquiring Nei Qiao sides three-phase current.
Further, the zero-sequence current is self-produced zero stream.
Further, transformer 101 is the 110kV transformers of internal bridge.
Further, the high-pressure side of transformer 101 be star-connection, the neutral-point solid ground of the star-connection.
The embodiment of the present invention four provides a kind of device of transformer zero-sequencedirectional protection under interior bridge mode, passes through zero-sequence current
Acquisition module obtains the zero-sequence current of enter line side current transformer, the zero-sequence current and two of Nei Qiao sides current transformer respectively
The vector sum of person, above-mentioned three it is any be more than rotection thresholds when, overcurrent protection action module cut-off breaker, to transformer carry out
Protection.This programme improves the sensitivity of transformer zero-sequencedirectional protection, makes protection action message.
Above device can perform transformer zero-sequencedirectional protection under the interior bridge mode that any embodiment of the present invention is provided
Method has the corresponding function module of execution method and advantageous effect.
Note that it above are only presently preferred embodiments of the present invention and institute's application technology principle.It will be appreciated by those skilled in the art that
The present invention is not limited to specific embodiment described here, can carry out for a person skilled in the art various apparent variations,
It readjusts and substitutes without departing from protection scope of the present invention.Therefore, although being carried out by above example to the present invention
It is described in further detail, but the present invention is not limited only to above example, without departing from the inventive concept, also
It can include other more equivalent embodiments, and the scope of the present invention is determined by scope of the appended claims.
Claims (6)
1. a kind of method of transformer zero-sequencedirectional protection under interior bridge mode, which is characterized in that including：
Obtain the zero-sequence current of enter line side current transformer respectively, the zero-sequence current of Nei Qiao sides current transformer and the two
Vector sum；
If above-mentioned three is any to be more than rotection thresholds, the breaker between transformer and inlet wire is disconnected；
Wherein, the high-pressure side of the transformer be star-connection, the neutral-point solid ground of the star-connection；The zero sequence electricity
It flows for self-produced zero stream.
2. according to the method described in claim 1, it is characterized in that：
The enter line side current transformer is installed on internal bridge enter line side, for acquiring enter line side three-phase current；
Nei Qiao sides current transformer is installed on internal bridge Nei Qiao sides, for acquiring Nei Qiao sides three-phase current.
3. according to the method described in claim 1, it is characterized in that：
The transformer is the 110kV transformers of internal bridge.
4. the device of transformer zero-sequencedirectional protection, the transformer including internal bridge, enter line side electric current under a kind of interior bridge mode
Mutual inductor, Nei Qiao sides current transformer and breaker, which is characterized in that further include：
Zero-sequence current acquisition module, for obtaining the zero-sequence current of the enter line side current transformer, the Nei Qiao sides electricity respectively
The zero-sequence current of current transformer and the vector sum of the two；
Overcurrent protection action module, for above-mentioned three is any be more than rotection thresholds when, disconnect the transformer and inlet wire it
Between the breaker；
Wherein, the high-pressure side of the transformer be star-connection, the neutral-point solid ground of the star-connection；The zero sequence electricity
It flows for self-produced zero stream.
5. device according to claim 4, it is characterised in that：
The enter line side current transformer is installed on internal bridge enter line side, for acquiring enter line side three-phase current；
Nei Qiao sides current transformer is installed on internal bridge Nei Qiao sides, for acquiring Nei Qiao sides three-phase current.
6. device according to claim 4, it is characterised in that：
The transformer is the 110kV transformers of internal bridge.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5790356A (en) * | 1994-10-13 | 1998-08-04 | Bottrell; Gerald W. | Transformer protection system for protecting source transformers from ill effects of zero-sequence currents |
| JP2005039956A (en) * | 2003-07-17 | 2005-02-10 | Tm T & D Kk | Protective relay device |
| CN103633620A (en) * | 2013-11-11 | 2014-03-12 | 中国南方电网有限责任公司超高压输电公司 | Novel configuration method for zero-sequence differential protection of converter transformer |
| CN105322651A (en) * | 2015-11-16 | 2016-02-10 | 江苏省电力公司镇江供电公司 | Automatic inputting method for standby power supply based on incomplete primary main connection on expanded inner bridge |
| CN105529687A (en) * | 2016-01-28 | 2016-04-27 | 南京南瑞继保电气有限公司 | Rapid zero-sequence overcurrent protection method for transformer |
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2016
- 2016-06-08 CN CN201610405343.5A patent/CN105977914B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5790356A (en) * | 1994-10-13 | 1998-08-04 | Bottrell; Gerald W. | Transformer protection system for protecting source transformers from ill effects of zero-sequence currents |
| JP2005039956A (en) * | 2003-07-17 | 2005-02-10 | Tm T & D Kk | Protective relay device |
| CN103633620A (en) * | 2013-11-11 | 2014-03-12 | 中国南方电网有限责任公司超高压输电公司 | Novel configuration method for zero-sequence differential protection of converter transformer |
| CN105322651A (en) * | 2015-11-16 | 2016-02-10 | 江苏省电力公司镇江供电公司 | Automatic inputting method for standby power supply based on incomplete primary main connection on expanded inner bridge |
| CN105529687A (en) * | 2016-01-28 | 2016-04-27 | 南京南瑞继保电气有限公司 | Rapid zero-sequence overcurrent protection method for transformer |
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