CN106199340B - A kind of method of discrimination and device of CT secondary circuit broken string - Google Patents
A kind of method of discrimination and device of CT secondary circuit broken string Download PDFInfo
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- CN106199340B CN106199340B CN201610785649.8A CN201610785649A CN106199340B CN 106199340 B CN106199340 B CN 106199340B CN 201610785649 A CN201610785649 A CN 201610785649A CN 106199340 B CN106199340 B CN 106199340B
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000012544 monitoring process Methods 0.000 claims description 7
- 230000002159 abnormal effect Effects 0.000 claims description 3
- 238000005070 sampling Methods 0.000 abstract description 7
- 241000272814 Anser sp. Species 0.000 abstract description 3
- 230000001681 protective effect Effects 0.000 abstract description 2
- 238000010276 construction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000004069 differentiation Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000011897 real-time detection Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/083—Locating faults in cables, transmission lines, or networks according to type of conductors in cables, e.g. underground
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
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- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Mathematical Physics (AREA)
- Theoretical Computer Science (AREA)
- Emergency Protection Circuit Devices (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The present invention relates to the method for discrimination and device of a kind of CT secondary circuit broken string.The present invention mainly by A, B, C three-phase current and after connecing, acquires zero-sequence current by accessing external zero sequence CT in real time.Meanwhile A, B, C three-phase current and external zero-sequence current are accessed into AD sampling channel, zero-sequence current is calculated in real time, compares the size of the difference of the zero-sequence current of acquisition and the zero-sequence current of calculating, to differentiate whether CT secondary circuit breaks.When CT secondary circuit broken string criterion meets, corresponding current channel quality is set in vain, and issue broken string GOOSE alarm signal, after protective device receives invalid sampling channel, is latched related protection, prevents false protection, improve the reliability of protection act.
Description
Technical field
The invention belongs to power system transformer substation fields of automation technology, and in particular to a kind of CT secondary circuit broken string is sentenced
Other method and device.
Background technique
In recent years, the intelligent substation based on 61850 standard of IEC has moved towards the all-round construction stage, and intelligent substation is with normal
Based on the sampling configuration for advising mutual inductor access analog input formula combining unit.Analog input formula combining unit is as process layer
Key equipment realizes the functions such as acquisition, AD conversion and the merging synchronism output of analog quantity.
In the design of analog input formula combining unit, the secondary side access analog input formula of conventional current mutual inductor is closed
And CT inside unit, mutual inductor secondary current is converted to the small signal of voltage by CT, for analog input formula combining unit A/D chip
It acquires and is converted into digital signal.
It is required according to " intelligent substation Protection Technology specification ", it should be only by two-way in analog input formula combining unit
Vertical sampling system is acquired, that is, is needed using double AD systems.And for the small CT in inside of simulation input formula combining unit
It is then single set configuration, double AD systems share.As shown in Figure 1, then double AD are sampled back when wherein any phase CT secondary circuit breaks
Road simultaneous faults.CT secondary circuit broken string occurs since double AD data are almost the same, under heavy load may directly result in protection mistake
Movement, CT secondary circuit broken string, which occurs, for the light hours generally not will cause protection misoperation, but there is also hidden danger and can not alert,
Lead to the differential protection misoperation when load aggravates.
Summary of the invention
The purpose of the present invention is to provide the method for discrimination and device of a kind of CT secondary circuit broken string, to solve CT bis- times
The problem of circuit breaking differential protection misoperation.
To achieve the goals above, technical solution of the present invention includes a kind of method of discrimination of CT secondary circuit broken string, packet
Include following steps:
Step 1, zero-sequence current 3I is acquired in real time0；
Step 2, it acquires monitoring in real time to three-phase current, calculates zero-sequence current 3I0'；
Step 3, real according to the acquisition zero-sequence current and the size for calculating zero-sequence current and the difference between them
When differentiate CT secondary circuit whether break: if calculate zero-sequence current and acquire zero-sequence current absolute value of the difference be greater than set it is poor
Value, and the maximum value in the three-phase current of acquisition, acquisition zero-sequence current is less than setting limit value, then determines that CT secondary circuit breaks.
Zero-sequence current 3I is acquired by external zero sequence CT0。
Calculate zero-sequence current: 3I0'=IA+IB+IC。
The criterion of CT secondary circuit broken string in the step 3 are as follows:
|IA+IB+IC-3I0|>Im (1)
|IA+IB+IC-3I0|>k*Max(IA, IB, IC) (2)
Max(IA, IB, IC, 3I0)<1.2In (3)
Wherein ImFor fixed threshold value, InFor rated current, K is multiple, IA, IB, ICFor the instantaneous value of three-phase current.
In the criterion, fixed threshold value ImTake 0.1In；K is taken as 0.5.
Criterion further includes CT secondary circuit broken string discrimination function soft pressing plate.
It is instantaneous to be latched CT secondary circuit broken string discrimination function 200ms if current channel SV 9-2 data quality is abnormal,
Until data just carry out the calculating of zero-sequence current after receiving quality valid data 20ms.A kind of differentiation of CT secondary circuit broken string
Device comprises the following modules:
(1) for acquiring zero-sequence current 3I in real time0Module；
(2) for acquiring monitoring in real time to three-phase current, zero-sequence current 3I is calculated0The module of '；
(3) real for the size and the difference between them according to the acquisition zero-sequence current and calculating zero-sequence current
When differentiate CT secondary circuit whether break: if calculate zero-sequence current and acquire zero-sequence current absolute value of the difference be greater than set it is poor
Value, and the maximum value in the three-phase current of acquisition, acquisition zero-sequence current is less than setting limit value, then determines CT secondary circuit broken string
Module.
The criterion of module for the judgement CT secondary circuit broken string are as follows:
|IA+IB+IC-3I0|>Im (1)
|IA+IB+IC-3I0|>k*Max(IA, IB, IC) (2)
Max(IA, IB, IC, 3I0)<1.2In (3)
Wherein ImFor fixed threshold value, InFor rated current, K is multiple, IA, IB, ICFor the instantaneous value of three-phase current.
The present invention passes through the zero-sequence current and external zero-sequence current pair of the three-phase current instantaneous value algebraical sum for calculating software
The method of ratio acquires monitoring in real time, judges whether CT secondary circuit breaks, and when CT secondary circuit broken string criterion meets, issues CT
Secondary circuit broken string GOOSE alarm signal, is latched related protection, prevents false protection, improve the reliability of protection act.
Detailed description of the invention
Fig. 1 is CT secondary circuit broken string sampling circuit schematic diagram；
Fig. 2 is self-produced zero sequence elementary diagram of the invention；
Fig. 3 is CT secondary circuit broken string decision logic block diagram of the invention.
Specific embodiment
Embodiments of the present invention are described further with reference to the accompanying drawing.
The present invention provides a kind of method of discrimination of CT secondary circuit broken string, the mainly three-phase electricity by calculating software
The method for flowing the zero-sequence current of instantaneous value algebraical sum and the external zero-sequence current comparison of acquisition acquires monitoring in real time, to judge CT bis-
Whether minor loop breaks.The method of the present invention can be applied to the differentiation of CT broken string inside analog input formula combining unit, improve
The reliability of analog quantity combining unit.
It is introduced by taking analog input formula combining unit as an example below.Certainly, method of discrimination of the invention can also be used for
Other CT acquire equipment.
As shown in Fig. 2, increasing by 1 phase on the basis of analog input formula combining unit exchanges A, B, C phase CT of acquisition plug-in unit
External zero sequence CT.I.e. by A, B, C three-phase current and after connecing, external zero sequence CT is accessed, zero-sequence current is acquired in real time, acquired
Hardware zero-sequence current be 3I0.Meanwhile A, B, C three-phase current and external zero-sequence current are accessed into analog input formula and merged
Unit AD acquisition channel, real-time software calculate the electric current of the algebraical sum of A, B, C three-phase current instantaneous value, are 3I0'=IA+IB+IC,
The zero-sequence current calculated is 3I0' judges whether to meet according to the size of the zero-sequence current of acquisition and the zero-sequence current of calculating
CT secondary circuit broken string criterion:
|IA+IB+IC-3I0|>Im (1)
|IA+IB+IC-3I0|>k*Max(IA, IB, IC) (2)
Max(IA, IB, IC, 3I0)<1.2In (3)
Wherein, ImFor fixed threshold value, InFor rated current, K is multiple.
If meet above-mentioned criterion formula (1), (2) and (3) simultaneously, and calculated through analog input formula combining unit CPU
And logic discrimination, then CT secondary circuit broken string decision logic is executed, as shown in figure 3, can the conjunction of real time discriminating analog input formula
And whether CT secondary circuit breaks inside unit, and after being judged to CT secondary circuit broken string, the corresponding whole group phase of self-produced zero sequence
Electric current output quality is set in vain, and concurrent CT secondary circuit broken string GOOSE alarm signal, protective device receives analog input formula and closes
And after the invalid sampling channel of unit transmission, it is latched related protection, prevents false protection.
Wherein, for discrimination formula (1), when systems are functioning properly, analog input formula combining unit three-phase CT and zero
Error is channel drift between sequence CT, as fixed threshold value ImTake 0.1In, channel drift can be escaped.
For discrimination formula (2), when the system failure, according to the Transfer characteristic of CT, error will between three-phase CT and zero sequence CT
Become larger；According to the characteristic of TPE mutual inductor, maximum instantaneous value error is below 10%.Therefore, in order to avoid wrong report CT bis- when failure
Minor loop broken string, the optimal value of k are 0.5.
CT secondary circuit is reported by mistake for discrimination formula (3), when to avoid failure to break and latch-up protection, three-phase CT and zero sequence
CT secondary circuit broken string is just carried out when any point phase current in CT is less than 1.2 times of rated current to differentiate；Meanwhile discrimination formula
(1) and the phase current in (2) is calculated by instantaneous value.
CT secondary circuit discrimination function soft pressing plate can be also arranged in the present invention inside analog input formula combining unit, can root
It is flexibly thrown according to requirement of engineering and moves back CT secondary circuit broken string criterion soft pressing plate.
Also according to the working principle of analog input formula combining unit in the present invention, if the SV9-2 data product of current channel
Matter is abnormal, then is instantaneously latched CT secondary circuit broken string discrimination function 200ms, until after receiving quality valid data 20ms, data
The calculating of zero-sequence current is carried out again.
The ADC chip that the present invention powers for unipolarity, CT secondary circuit broken string mutually can collect DC current, even if mould
Without input current, analog input formula combining unit inside CT secondary circuit broken string criterion outside analog quantity input type combining unit
It can meet, i.e., can be detected whether CT secondary circuit breaks before analog quantity combining unit device scene is put into operation.And for bipolar
Property power supply ADC chip, inside analog input formula combining unit after CT secondary circuit broken string, phase current sampling value is about 0, only
Have to have outside CT inside analog input formula combining unit and can just detect that CT secondary circuit breaks when electric current.Ensure in this respect
In the case that CT secondary circuit breaks, analog input formula combining unit can real-time detection, and corresponding current channel quality is set
To be invalid, instantaneous latch-up protection, while avoiding protection misoperation.
The discriminating gear embodiment of CT secondary circuit broken string
A kind of discriminating gear of CT secondary circuit broken string, comprises the following modules:
(1) for acquiring zero-sequence current 3I in real time0Module；
(2) for acquiring monitoring in real time to three-phase current, zero-sequence current 3I is calculated0The module of '；
(3) real for the size and the difference between them according to the acquisition zero-sequence current and calculating zero-sequence current
When differentiate CT secondary circuit whether break: if calculate zero-sequence current and acquire zero-sequence current absolute value of the difference be greater than set it is poor
Value, and the maximum value in the three-phase current of acquisition, acquisition zero-sequence current is less than setting limit value, then determines CT secondary circuit broken string
Module.
Signified device in above-mentioned apparatus embodiment is actually based on a kind of computer solution party of the method for the present invention process
Case, i.e., a kind of functional module construction, above-mentioned module are treatment progress corresponding with method flow.The software can be run on
In smart substation equipment.Since sufficiently clear is complete for the introduction to the above method, and the device that the present embodiment is claimed
Actually a kind of functional module construction, therefore be no longer described in detail.
Claims (7)
1. a kind of method of discrimination of CT secondary circuit broken string, it is characterised in that: the following steps are included:
Step 1, zero-sequence current 3I is acquired in real time0；
Step 2, it acquires monitoring in real time to three-phase current, calculates zero-sequence current 3I0'；
Step 3, according to the acquisition zero-sequence current and the size for calculating zero-sequence current and the difference between them, sentence in real time
Whether other CT secondary circuit breaks: if the absolute value of the difference for calculating zero-sequence current and acquisition zero-sequence current is greater than setting difference, and
The three-phase current of acquisition, the maximum value acquired in zero-sequence current are less than setting limit value, then determine that CT secondary circuit breaks；
The criterion of CT secondary circuit broken string in the step 3 are as follows:
| IA + IB + IC -3I0 | > Im(1)
| IA + IB + IC -3I0 | > k * Max (IA, IB, IC) (2)
Max(IA, IB, IC, 3I0) < 1.2 In (3)
Wherein ImFor fixed threshold value, InFor rated current, k is multiple, IA, IB, ICFor the instantaneous value of three-phase current.
2. the method for discrimination of CT secondary circuit broken string according to claim 1, it is characterised in that: adopted by external zero sequence CT
Collect zero-sequence current 3I0。
3. the method for discrimination of CT secondary circuit broken string according to claim 1, it is characterised in that: calculate zero-sequence current: 3I0'
=IA+IB+IC。
4. the method for discrimination of CT secondary circuit broken string according to claim 1, it is characterised in that: in the criterion, Gu
Set threshold value ImTake 0.1In；K is taken as 0.5.
5. the method for discrimination of CT secondary circuit broken string according to claim 1, it is characterised in that: criterion further includes CT bis- times
Circuit breaking discrimination function soft pressing plate.
6. the method for discrimination of CT secondary circuit broken string according to claim 1, it is characterised in that: if current channel SV
9-2 data quality is abnormal, then CT secondary circuit broken string 200 ms of discrimination function is instantaneously latched, until receiving quality valid data 20
After ms, data just carry out the calculating of zero-sequence current.
7. a kind of discriminating gear of CT secondary circuit broken string, it is characterised in that: comprise the following modules:
(1) for acquiring zero-sequence current 3I in real time0Module；
(2) for acquiring monitoring in real time to three-phase current, zero-sequence current 3I is calculated0The module of '；
(3) for being sentenced in real time according to the acquisition zero-sequence current and the size for calculating zero-sequence current and the difference between them
Whether other CT secondary circuit breaks: if the absolute value of the difference for calculating zero-sequence current and acquisition zero-sequence current is greater than setting difference, and
The three-phase current of acquisition, the maximum value acquired in zero-sequence current are less than setting limit value, then determine the module of CT secondary circuit broken string；
The criterion of module for CT secondary circuit broken string are as follows:
| IA + IB + IC -3I0 | > Im(1)
| IA + IB + IC -3I0 | > k * Max (IA, IB, IC) (2)
Max(IA, IB, IC, 3I0) < 1.2 In (3)
Wherein ImFor fixed threshold value, InFor rated current, k is multiple, IA, IB, ICFor the instantaneous value of three-phase current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201610785649.8A CN106199340B (en) | 2016-08-30 | 2016-08-30 | A kind of method of discrimination and device of CT secondary circuit broken string |
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| CN201610785649.8A CN106199340B (en) | 2016-08-30 | 2016-08-30 | A kind of method of discrimination and device of CT secondary circuit broken string |
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| CN106199340B true CN106199340B (en) | 2019-01-01 |
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| CN107064689B (en) * | 2017-05-02 | 2019-10-22 | 许继电气股份有限公司 | A kind of analogy method and system of transformer TA broken string |
| CN112731206B (en) * | 2020-12-07 | 2023-08-15 | 南京国电南自电网自动化有限公司 | Analog input type merging unit protection current transformer broken line detection method |
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| CN104882866B (en) * | 2015-05-27 | 2017-09-19 | 北京四方继保自动化股份有限公司 | A kind of method that protection device differentiates CT secondary sides broken string using pulsed quantity |
| CN105005014B (en) * | 2015-07-07 | 2017-11-21 | 南京国电南自电网自动化有限公司 | A kind of combining unit with protective current transformer output abnormality detection function |
| CN105529687B (en) * | 2016-01-28 | 2017-12-22 | 南京南瑞继保电气有限公司 | A kind of quick zero-sequencedirectional protection method of transformer |
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