CN104967102B - A kind of mother or step charge over-current protection method - Google Patents
A kind of mother or step charge over-current protection method Download PDFInfo
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- CN104967102B CN104967102B CN201510369227.8A CN201510369227A CN104967102B CN 104967102 B CN104967102 B CN 104967102B CN 201510369227 A CN201510369227 A CN 201510369227A CN 104967102 B CN104967102 B CN 104967102B
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- 238000000034 method Methods 0.000 title claims abstract description 20
- 238000005070 sampling Methods 0.000 claims description 12
- 230000007257 malfunction Effects 0.000 abstract description 7
- 230000001681 protective effect Effects 0.000 abstract description 5
- 230000005611 electricity Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000011218 segmentation Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 230000004069 differentiation Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Abstract
The invention discloses a kind of mother or step charge over-current protection methods; this method is mainly used in mother/section switch protective device of intelligent grid; second harmonic and triple-frequency harmonics "or" closedown mode are used first; then mother/segmented current waveform is subjected to symmetry comparison again, the overcurrent protection of this phase is opened if mother/be segmented certain phase current waveform symmetrically.Since mother/segmented current has point-symmetry property more than more than 1/4 cycle to be unsatisfactory for when closing a floodgate with main transformer or circuit; and mother/segmented current waveform symmetry meets always during He Zhong Library; therefore; it can be by differentiating whether mother/segmented current waveform symmetrically identifies failure and normal combined floodgate; mother/step charge over-current protection malfunction when anti-stop-band main transformer or circuit close a floodgate; make charging overcurrent protection not malfunction in normal close a floodgate, quick acting during He Zhong Library improves the reliability of protective device.
Description
Technical field
The invention belongs to Relay Protection Technology in Power System fields, and in particular to a kind of mother or step charge overcurrent protection
Method.
Background technology
The charging overcurrent protection of mother/section switch belongs to breaker protection, aims at mother/section switch to standby
It is used with busbar charging.When being charged by mother/segmentation to auxiliary bus-bar, if auxiliary bus-bar and its element of connection are faulty,
Then charge overcurrent protection snap action, disconnects mother/section switch, prevents expansion accident, ensures that non-faulting busbar is normally transported
Row.After charging, mother/step charge overcurrent protection is exited.For newly put into operation or overhaul after main transformer, closing mother
After connection/section switch, exciting current can be generated；Equally, for newly put into operation or overhaul after circuit, there are certain electricity for itself
Appearance and direct-to-ground capacitance, after mother/section switch is closed, can also generate dash current.Due to the overcurrent protection definite value that charges
Relatively low, the time limit is very short, may cause charging over-current protection malfunction, charging is caused to fail.
Invention content
The object of the present invention is to provide a kind of mother or step charge over-current protection method, to solve mother/segmentation open circuit
The problem of device band main transformer or circuit may cause mother or step charge over-current protection malfunction when closing a floodgate.
In order to achieve the goal above, the technical solution adopted in the present invention is：A kind of mother or step charge overcurrent protection
The step of method, this method, is as follows：
(1) overcurrent protection, which starts, differentiates：A, any phase current I is more than overcurrent protection current ration I in B, C three-phase currentset
When overcurrent protection start；
(2) second harmonic and triple-frequency harmonics content in A, B, C three-phase current are calculated, when the fundamental wave electricity of any one phase current
Flow I1With overcurrent protection current ration IsetRatio be more than setting multiple k and its second harmonic I2Or triple-frequency harmonics I3Content is with being somebody's turn to do
Phase fundamental current I1Ratio be more than corresponding setting ratio kxb2、kxb3When, judge phase harmonic content height；
(3) if when not high per phase harmonic content, directly open 3 stage overcurrent protection；If there is the harmonic wave of any one electric current
When content is high, then differential is carried out to every phase current, filter out the DC component in electric current；
(4) the preceding half cycle to the three-phase current waveform after differential and second half carry out symmetry comparison respectively, continuous to compare
The sampled point of half period, when the ratio of the asymmetric points of waveform and the number of half period sampled point is more than setting value,
Judge phase current waveform asymmetry, be then latched the phase overcurrent protection；When any phase current waveform is symmetrical, open this phase overcurrent
Protection.
It is to the differential equation of every phase current progress differential in the step (3)：
ΔiK=iK-iK-1
I in above formulaKFor current point sampled value, iK-1For former point sampled value, Δ iKFor the current sampling data after differential.
When comparing in the step (4) the preceding half cycle and second half of the three-phase current waveform after differential progress symmetry,
The discrimination formula that any one sampling point-symmetry property compares is as follows：
|I(k)+I(k+π)|/I(k)-I(k+π)|≥0.4
I (k), I (k+ π) are the current sampling data after differential in above formula, and I (k) is point sampling value, I before preceding half cycle is taken in
(k+ π) is corresponding sampled value in second half.
Multiple k is set as 0.95 in the step (2).
K in the step (2)xb2It is 0.15, kxb3It is 0.2.
In the step (1) when overcurrent protection is not actuated, it is directly latched 3 stage overcurrent protection.
The mother or step charge over-current protection method of the present invention is mainly used in mother/section switch of intelligent grid
In protective device, first using second harmonic and triple-frequency harmonics "or" closedown mode, then again by mother/segmented current waveform into
Row symmetry compares, if mother/be segmented certain phase current waveform symmetrically if open the overcurrent protection of this phase.Due to band main transformer or circuit
Mother/segmented current has point-symmetry property more than more than 1/4 cycle to be unsatisfactory for during combined floodgate, and mother/segmentation during He Zhong Library
Current waveform symmetry meets always, therefore, can be by differentiating whether mother/segmented current waveform symmetrically identifies failure and just
It often closes a floodgate, mother/step charge over-current protection malfunction when anti-stop-band main transformer or circuit close a floodgate makes charging overcurrent protection in normal occlusion
Not malfunction during lock, quick acting during He Zhong Library improve the reliability of protective device.
Description of the drawings
Fig. 1 is double bus scheme schematic diagram；
Fig. 2 is mother or step charge overcurrent protection fault recognition method flow chart；
Fig. 3 differentiates sampling schematic diagram for mother or segmented current symmetry.
Specific embodiment
Below in conjunction with the accompanying drawings and the present invention is described further in specific embodiment.
For in a manner of double bus scheme, double bus scheme schematic diagram is as shown in Figure 1.1# elements during normal operation
1G, 2G are closed, and 1DL is disconnected；2# elements 1G is closed, 2G points, and 2DL is closed；3# elements 1G is closed, 2G points, and 3DL is closed；1G points of 4# elements, 2G are closed,
4DL is closed.I master tape electricity during normal operation, II is female not charged, closes a floodgate from I mother to 1DL during II female charging, since 4# elements are transformation
Device may flow through very big exciting current when busbar breaker is closed a floodgate in mother electric current, since charging overcurrent protection definite value is relatively low,
Time limit is very short, may cause charging over-current protection malfunction, charging is caused to fail.
It is illustrated in figure 2 the flow chart of mother of the present invention or step charge over-current protection method, as seen from the figure, this method
Step is as follows：
(1) overcurrent protection, which starts, differentiates：A, mistake when any phase current is more than overcurrent protection current ration in B, C three-phase current
Stream protection starts, and discriminant equation is：
I ＞ Iset
Amplitudes of the I for mother/segmented current, I in above formulasetFor overcurrent protection current ration；
In this step, when overcurrent protection is not actuated, no longer to the harmonic content in mother/segmented current and mother/
Segmented current waveform symmetry is differentiated that the i.e. differentiation without step (2)~(4) is directly latched 3 stage overcurrent protection.
(2) second harmonic and triple-frequency harmonics content in A, B, C three-phase current are calculated, when the fundamental wave electricity of any one phase current
Flow I1With overcurrent protection current ration IsetRatio be more than setting multiple k and its second harmonic I2Or triple-frequency harmonics I3Content is with being somebody's turn to do
Phase fundamental current I1Ratio be more than corresponding setting ratio kxb2、kxb3When, judge phase harmonic content height.
Here setting multiple k preferably 0.95, kxb2It is 0.15, kxb3It is 0.2, then corresponding discriminant equation is：
(3) during if per second harmonic and not high triple-frequency harmonics content in phase current, no longer to mother/segmented current wave
Shape is differentiated, directly opens 3 stage overcurrent protection；If have the harmonic content of any one electric current it is high when, to every phase current into
Row differential filters out the DC component in electric current；
Per phase current, the differential equation of progress differential is：
ΔiK=iK-iK-1
I in above formulaKFor current point sampled value, iK-1For former point sampled value, Δ iKFor the current sampling data after differential.
(4) the preceding half cycle to the three-phase current waveform after differential and second half carry out symmetry comparison respectively, continuous to compare
The sampled point of half period, when the ratio of the asymmetric points of waveform and the number of half period sampled point is more than setting value,
Judge phase current waveform asymmetry, be then latched the phase overcurrent protection；When any phase current waveform is symmetrical, open this phase overcurrent
Protection.
When preceding half cycle and second half progress symmetry to the three-phase current waveform after differential compare, any one sampled point
The discrimination formula that symmetry compares is as follows：
|I(k)+I(k+π)|/I(k)-I(k+π)|≥0.4
I (k), I (k+ π) are the current sampling data that DC component was filtered out after differential in above formula, and I (k) is on preceding half cycle
Current point sampled value, I (k+ π) are corresponding sampled value (preceding half cycle and poor half of the cycle of second half) in second half, and above-mentioned micro-
Equation is divided to connect, that is, is had：I (k)=Δ iK, I (k+ π)=Δ iK+π。
Certainly, above-mentioned carry out symmetry is sentenced otherwise and there are many corresponding discriminant equations, does not enumerate here.
If sampling per cycle at 24 points, the sampled point of half cycles is 12 points, then when the asymmetric points of waveform are more than 5
Then differentiate phase current waveform asymmetry, that is to say, that the asymmetric points of waveform and the number of half period sampled point here
Ratio for 5/12, certainly, setting value here can be determined according to actual conditions, be not especially limited.
The over-current protection method function module independent as one that charge of the present invention, is placed on mother/section switch
In protective device, which puts into mother/section switch charging, after charging, mother/step charge mistake
Stream protection is exited.The function module use differential after mother/segmented current waveform before the sampled data of half cycle and second half by
Point carries out symmetry comparison, as shown in Figure 3.Due to band main transformer or circuit close a floodgate when mother/segmented current have more than 1/4 cycle with
On point-symmetry property be unsatisfactory for, therefore, the function module energy reliable recognition failure and normal close a floodgate.
Above example is only used for the core concept for helping to understand the present invention, it is impossible to the present invention is limited with this, for ability
The technical staff in domain, every thought according to the present invention modify or equivalently replace the present invention, in specific embodiment
And any change done in application range, it should all be included in the protection scope of the present invention.
Claims (6)
1. a kind of mother or step charge over-current protection method, which is characterized in that the step of this method is as follows：
(1) overcurrent protection, which starts, differentiates：A, any phase current I is more than overcurrent protection current ration I in B, C three-phase currentsetWhen mistake
Stream protection starts；
(2) second harmonic and triple-frequency harmonics content in A, B, C three-phase current are calculated, as the fundamental current I of any one phase current1
With overcurrent protection current ration IsetRatio be more than setting multiple k and its second harmonic I2Or triple-frequency harmonics I3Content and the phase base
Wave electric current I1Ratio be more than corresponding setting ratio kxb2、kxb3When, judge phase harmonic content height；
(3) if when not high per phase harmonic content, directly open 3 stage overcurrent protection；If there is the harmonic content of any one electric current
Gao Shi then carries out differential to every phase current, filters out the DC component in electric current；
(4) the preceding half cycle to the three-phase current waveform after differential and second half progress symmetry comparison respectively, continuously relatively half
The sampled point in period, when the ratio of the asymmetric points of waveform and the number of half period sampled point is more than setting value, judgement
The phase current waveform is asymmetric, then is latched the phase overcurrent protection；When any phase current waveform is symmetrical, open this phase overcurrent is protected
Shield.
2. mother according to claim 1 or step charge over-current protection method, it is characterised in that：In the step (3)
To every phase current carry out differential the differential equation be：
ΔiK=iK-iK-1
I in above formulaKFor current point sampled value, iK-1For former point sampled value, Δ iKFor the current sampling data after differential.
3. mother according to claim 2 or step charge over-current protection method, it is characterised in that：In the step (4)
When preceding half cycle and second half progress symmetry to the three-phase current waveform after differential compare, any one sampling point-symmetry property ratio
Compared with discrimination formula it is as follows：
|I(k)+I(k+π)|/|I(k)-I(k+π)|≥0.4
I (k), I (k+ π) are the current sampling data after differential in above formula, and I (k) is point sampling value, I (k+ π) before preceding half cycle is taken in
For sampled value corresponding in second half.
4. mother according to claim 1 or step charge over-current protection method, it is characterised in that：In the step (2)
Multiple k is set as 0.95.
5. mother according to claim 1 or step charge over-current protection method, it is characterised in that：In the step (2)
kxb2It is 0.15, kxb3It is 0.2.
6. mother or step charge over-current protection method according to Claims 1 to 5 any one, it is characterised in that：Institute
It states in step (1) when overcurrent protection is not actuated, is directly latched 3 stage overcurrent protection.
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| CN201510369227.8A CN104967102B (en) | 2015-06-28 | 2015-06-28 | A kind of mother or step charge over-current protection method |
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| CN104967102B true CN104967102B (en) | 2018-06-26 |
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| CN108767831B (en) * | 2018-06-25 | 2020-05-05 | 国网福建省电力有限公司 | Overcurrent subsection fast protection method for current-limiting resistor of flexible direct-current power transmission system |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102064613A (en) * | 2011-01-13 | 2011-05-18 | 许继电气股份有限公司 | Fault locking method for relay protection in digital substation |
| CN104319736A (en) * | 2014-10-17 | 2015-01-28 | 许继集团有限公司 | Differential protection method for extra-high voltage transformer |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20070114593A (en) * | 2006-05-29 | 2007-12-04 | 주식회사 대우일렉트로닉스 | Universal power supply integrated in car stereo |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102064613A (en) * | 2011-01-13 | 2011-05-18 | 许继电气股份有限公司 | Fault locking method for relay protection in digital substation |
| CN104319736A (en) * | 2014-10-17 | 2015-01-28 | 许继集团有限公司 | Differential protection method for extra-high voltage transformer |
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