CN106199340A - The method of discrimination of a kind of CT secondary circuit broken string and device - Google Patents
The method of discrimination of a kind of CT secondary circuit broken string and device Download PDFInfo
- Publication number
- CN106199340A CN106199340A CN201610785649.8A CN201610785649A CN106199340A CN 106199340 A CN106199340 A CN 106199340A CN 201610785649 A CN201610785649 A CN 201610785649A CN 106199340 A CN106199340 A CN 106199340A
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- zero
- secondary circuit
- broken string
- sequence current
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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
Abstract
The present invention relates to method of discrimination and the device of a kind of CT secondary circuit broken string.The present invention is mainly by A, B, C three-phase current and after connecing, by accessing external zero sequence CT Real-time Collection zero-sequence current.Meanwhile, A, B, C three-phase current and external zero-sequence current are all accessed AD sampling channel, calculates zero-sequence current in real time, compare the size of the difference of the zero-sequence current of collection and the zero-sequence current of calculating, differentiate whether CT secondary circuit breaks.When CT secondary circuit broken string criterion meets, it is invalid corresponding current channel quality to be set to, and sends broken string GOOSE warning signal, after protection device receives invalid sampling channel, and the relevant protection of locking, prevent false protection, improve the reliability of protection act.
Description
Technical field
The invention belongs to power system transformer substation technical field of automation, be specifically related to sentencing of a kind of CT secondary circuit broken string
Other method and device.
Background technology
In recent years, intelligent substation based on IEC 61850 standard has moved towards the all-round construction stage, and intelligent substation is with often
It is main that rule transformer accesses the sampling configuration of analog input formula combining unit.Analog input formula combining unit is as process layer
Key equipment, it is achieved that the functions such as the collection of analog quantity, AD conversion and merging synchronism output.
In analog input formula combining unit designs, the secondary side of conventional current transformer accesses analog input formula and closes
And transformer secondary current is converted to voltage small-signal, for analog input formula combining unit A/D chip by unit internal CT, CT
Gather and be converted into digital signal.
According to " intelligent substation Protection Technology specification " requirement, formula combining unit planted agent is only by two-way for analog input
Vertical sampling system is acquired, and namely needs to use double AD system.And for simulating the little CT in inside of input type combining unit
Being then single set configuration, double AD systems share.As it is shown in figure 1, when wherein arbitrarily phase CT secondary circuit broken string, the most double AD sample back
Road simultaneous faults.Owing to double AD data are basically identical, under heavy load, occur CT secondary circuit broken string may directly result in protection by mistake
Action, light hours generation CT secondary circuit broken string does not typically result in protection misoperation, but there is also hidden danger and cannot alert,
Cause the differential protection misoperation when load increases the weight of.
Summary of the invention
It is an object of the invention to provide method of discrimination and the device of a kind of CT secondary circuit broken string, in order to solve CT bis-times
The problem of circuit breaking differential protection misoperation.
To achieve these goals, technical scheme includes the method for discrimination that a kind of CT secondary circuit breaks, bag
Include following steps:
Step 1, Real-time Collection zero-sequence current 3I0；
Step 2, monitors three-phase current Real-time Collection, calculates zero-sequence current 3I0＇；
Step 3, according to described collection zero-sequence current and the size calculating zero-sequence current, and the difference between them, real
Time differentiate whether CT secondary circuit breaks: if gathering zero-sequence current and calculating zero-sequence current less than setting limit value, and they it
Between difference more than set difference, then judge CT secondary circuit broken string.
Zero-sequence current 3I is gathered by external zero sequence CT0。
Calculate zero-sequence current: 3I0＇=IA+IB+IC。
The criterion of the CT secondary circuit broken string in described step 3 is:
|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 fixing threshold value, InFor rated current, K is multiple, IA, IB, ICInstantaneous value for three-phase current.
In described criterion formula (1), fixing threshold value ImTake 0.1In；In described discrimination formula (2), k is taken as 0.5.
Criterion also includes that the CT broken string soft pressing plate of criterion puts into state.
If current channel SV 9-2 data quality is abnormal, the most instantaneous locking CT secondary circuit broken string discrimination function 200ms,
Until after receiving quality valid data 20ms, data just carry out the calculating of zero-sequence current.A kind of differentiation of CT secondary circuit broken string
Device, including with lower module:
(1) for Real-time Collection zero-sequence current 3I0Module；
(2) for three-phase current Real-time Collection is monitored, zero-sequence current 3I is calculated0The module of ＇；
(3) for the size according to described collection zero-sequence current with calculating zero-sequence current, and the difference between them, real
Time differentiate whether CT secondary circuit breaks: if gathering zero-sequence current and calculating zero-sequence current less than setting limit value, and they it
Between difference more than set difference, then judge CT secondary circuit broken string module.
For the described criterion judging module that CT secondary circuit breaks as:
|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 fixing threshold value, InFor rated current, K is multiple, IA, IB, ICInstantaneous value for three-phase current.
The present invention is by by the zero-sequence current of the three-phase current instantaneous value algebraical sum of computed in software and external zero-sequence current pair
The method Real-time Collection monitoring of ratio, it is judged that whether CT secondary circuit breaks, when CT secondary circuit broken string criterion meets, sends CT
Secondary circuit broken string GOOSE warning signal, the relevant protection of locking, prevent false protection, improve the reliability of protection act.
Accompanying drawing explanation
Fig. 1 is CT secondary circuit broken string sampling circuit schematic diagram；
Fig. 2 is the self-produced zero sequence elementary diagram of the present invention；
Fig. 3 is the CT secondary circuit broken string decision logic block diagram of the present invention.
Detailed description of the invention
Below in conjunction with the accompanying drawings embodiments of the present invention are described further.
The invention provides the method for discrimination of a kind of CT secondary circuit broken string, mainly by the three-phase electricity to computed in software
The zero-sequence current of stream instantaneous value algebraical sum and the method Real-time Collection monitoring of the external zero-sequence current contrast of collection, judge CT bis-
Whether minor loop breaks.The inventive method can be applicable to the differentiation of analog input formula combining unit internal CT broken string, improves
The reliability of analog quantity combining unit.
It is introduced as a example by analog input formula combining unit below.Certainly, the method for discrimination of the present invention can also be used for
Other CT collecting device.
As in figure 2 it is shown, on the basis of the exchange of analog input formula combining unit gathers A, B, C phase CT of plug-in unit, increase by 1 phase
External zero sequence CT.Will A, B, C three-phase current after connecing, access external zero sequence CT, in real time zero-sequence current be acquired, gather
Hardware zero-sequence current be 3I0.Meanwhile, A, B, C three-phase current and external zero-sequence current all access analog input formula merge
Unit AD acquisition channel, real-time software calculates the electric current of the algebraical sum of A, B, C three-phase current instantaneous value, for 3I0＇=IA+IB+IC,
The zero-sequence current i.e. calculated is 3I0＇, according to the size of the zero-sequence current gathered with the zero-sequence current of calculating, it may be judged whether meet
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 fixing threshold value, InFor rated current, K is multiple.
If meet above-mentioned criterion formula (1), (2) and (3), and calculate through analog input formula combining unit CPU simultaneously
And logic discrimination, then perform CT secondary circuit broken string decision logic, as it is shown on figure 3, can real time discriminating analog input formula close
And whether the internal CT secondary circuit of unit breaks, after being once judged to CT secondary circuit broken string, the whole group of phase that self-produced zero sequence is corresponding
It is invalid that electric current output quality is put, and concurrent CT secondary circuit broken string GOOSE warning signal, protection device receives analog input formula and closes
And after the invalid sampling channel of unit transmission, the relevant protection of locking, prevent false protection.
Wherein, for discrimination formula (1), when systems are functioning properly, analog input formula combining unit three-phase CT and zero
Between sequence CT, error is passage drift, as fixing threshold value ImTake 0.1In, passage drift can be escaped.
For discrimination formula (2), when the system failure, according to the Transfer characteristic of CT, between three-phase CT and zero sequence CT, error will
Become big；According to the characteristic of TPE transformer, maximum instantaneous value error is below 10%.Therefore, in order to avoid reporting CT bis-during fault by mistake
Minor loop breaks, and the optimum value of k is 0.5.
For discrimination formula (3), wrong report CT secondary circuit broken string during for avoiding fault and latch-up protection, three-phase CT and zero sequence
Just carry out CT secondary circuit broken string when any point phase current in CT is less than 1.2 times of rated current to differentiate；Simultaneously, it determines formula
(1) phase current and in (2) is all to calculate by instantaneous value.
The present invention also can arrange the CT soft pressing plate of secondary circuit discrimination function inside analog input formula combining unit, can root
Throw flexibly according to requirement of engineering and move back CT secondary circuit broken string criterion pressing plate input state.
Always according to the operation principle of analog input formula combining unit in the present invention, if the SV9-2 data product of current channel
Matter is abnormal, the most instantaneous locking CT secondary circuit broken string discrimination function 200ms, until after receiving quality valid data 20ms, data
Carry out the calculating of zero-sequence current again.
The ADC chip that the present invention powers for unipolarity, CT secondary circuit broken string can collect DC current mutually, even if mould
Analog quantity input type combining unit is outside without input current, and analog input formula combining unit internal CT secondary circuit broken string criterion is also
Can meet, i.e. can detect whether CT secondary circuit breaks before putting into operation in analog quantity combining unit device scene.And for bipolar
Property the ADC chip powered, after analog input formula combining unit internal CT secondary circuit broken string, phase current sampling value is about 0, only
Have when having electric current outside the internal CT of analog input formula combining unit and just can detect that CT secondary circuit breaks.Guarantee in this respect
In the case of CT secondary circuit broken string, analog input formula combining unit can detect in real time, and corresponding current channel quality is put
For invalid, instantaneous latch-up protection, avoid protection misoperation simultaneously.
The discriminating gear embodiment of CT secondary circuit broken string
A kind of discriminating gear of CT secondary circuit broken string, including with lower module:
(1) for Real-time Collection zero-sequence current 3I0Module；
(2) for three-phase current Real-time Collection is monitored, zero-sequence current 3I is calculated0The module of ＇；
(3) for the size according to described collection zero-sequence current with calculating zero-sequence current, and the difference between them, real
Time differentiate whether CT secondary circuit breaks: if gathering zero-sequence current and calculating zero-sequence current less than setting limit value, and they it
Between difference more than set difference, then judge CT secondary circuit broken string module.
The device of indication in said apparatus embodiment, is actually based on a kind of computer solution party of the inventive method flow process
Case, i.e. a kind of functional module construction, above-mentioned module is the treatment progress corresponding with method flow.This software can run on
In intelligent substation equipment.Due to complete to the introduction sufficiently clear of said method, and the device that the present embodiment is claimed
A kind of functional module construction, therefore be described the most in detail.
Claims (9)
1. the method for discrimination of a CT secondary circuit broken string, it is characterised in that comprise the following steps:
Step 1, Real-time Collection zero-sequence current 3I0；
Step 2, monitors three-phase current Real-time Collection, calculates zero-sequence current 3I0＇；
Step 3, according to described collection zero-sequence current and the size calculating zero-sequence current, and the difference between them, sentence in real time
Whether other CT secondary circuit breaks: if gathering zero-sequence current and calculating zero-sequence current less than setting limit value, and between them
Difference more than setting difference, then judges CT secondary circuit broken string.
The method of discrimination of CT secondary circuit the most according to claim 1 broken string, it is characterised in that: adopted by external zero sequence CT
Collection zero-sequence current 3I0。
The method of discrimination of CT secondary circuit the most according to claim 1 broken string, it is characterised in that: calculate zero-sequence current: 3I0＇
=IA+IB+IC。
The method of discrimination of CT secondary circuit the most according to claim 1 broken string, it is characterised in that: the CT in described step 3
The criterion of secondary circuit broken string is:
|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 fixing threshold value, InFor rated current, K is multiple, IA, IB, ICInstantaneous value for three-phase current.
5. the method for discrimination broken according to the CT secondary circuit described in claim 1 or 4, it is characterised in that: described criterion is public
In formula (1), fixing threshold value ImTake 0.1In；In described discrimination formula (2), k is taken as 0.5.
The method of discrimination of CT secondary circuit the most according to claim 1 broken string, it is characterised in that: criterion also includes that CT breaks
The soft pressing plate of criterion puts into state.
7. the method for discrimination broken according to the CT secondary circuit described in claim 1 or 4, it is characterised in that: if current channel
SV 9-2 data quality is abnormal, and the most instantaneous locking CT secondary circuit broken string discrimination function 200ms, until receiving quality valid data
After 20ms, data just carry out the calculating of zero-sequence current.
8. the discriminating gear of a CT secondary circuit broken string, it is characterised in that: include with lower module:
(1) for Real-time Collection zero-sequence current 3I0Module；
(2) for three-phase current Real-time Collection is monitored, zero-sequence current 3I is calculated0The module of ＇；
(3) for the size according to described collection zero-sequence current with calculating zero-sequence current, and the difference between them, sentence in real time
Whether other CT secondary circuit breaks: if gathering zero-sequence current and calculating zero-sequence current less than setting limit value, and between them
Difference more than setting difference, then judges the module of CT secondary circuit broken string.
The discriminating gear of CT secondary circuit the most according to claim 8 broken string, it is characterised in that: for described CT secondary returning
The criterion of the module of road broken string is:
|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 fixing threshold value, InFor rated current, K is multiple, IA, IB, ICInstantaneous value for three-phase current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610785649.8A CN106199340B (en) | 2016-08-30 | 2016-08-30 | A kind of method of discrimination and device of CT secondary circuit broken string |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| 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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| CN106199340A true CN106199340A (en) | 2016-12-07 |
| CN106199340B CN106199340B (en) | 2019-01-01 |
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| CN201610785649.8A Active 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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Cited By (2)
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| CN107064689A (en) * | 2017-05-02 | 2017-08-18 | 许继电气股份有限公司 | A kind of analogy method and system of transformer TA broken strings |
| CN112731206A (en) * | 2020-12-07 | 2021-04-30 | 南京国电南自电网自动化有限公司 | Analog input type merging unit protection current transformer disconnection detection method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107064689A (en) * | 2017-05-02 | 2017-08-18 | 许继电气股份有限公司 | A kind of analogy method and system of transformer TA broken strings |
| 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 |
| CN112731206A (en) * | 2020-12-07 | 2021-04-30 | 南京国电南自电网自动化有限公司 | Analog input type merging unit protection current transformer disconnection detection method |
| 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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