CN103513145B - Current transformer disconnection detection method and device - Google Patents
Current transformer disconnection detection method and device Download PDFInfo
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- CN103513145B CN103513145B CN201210226731.9A CN201210226731A CN103513145B CN 103513145 B CN103513145 B CN 103513145B CN 201210226731 A CN201210226731 A CN 201210226731A CN 103513145 B CN103513145 B CN 103513145B
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Abstract
The embodiment of the present invention proposes a kind of current transformer disconnection detection method and device.This CT wire break detection method includes: be integrated the current sampling data in adjacent very first time window and the second time window, described current sampling data is to obtain by sampling the output of current transformer, thus obtain first integral value and the second integral value of corresponding second time window of corresponding very first time window, wherein, the equal in magnitude and time window width of first, second time window is less than 1/2 cycle of sample rate current；By first integral value divided by second integral value, obtain the first quotient；Judge whether described first quotient meets broken string criterion, if it is satisfied, then be judged as occurring in that current transformer circuit supervision fail.Wherein, described first, second time window width is preferably 1/4 cycle of sample rate current.
Description
Technical field
The present invention relates to relay protection field, particularly to a kind of current transformer (CT) wire break detection method, CT breaks
Detect device and include the relay protection device of CT broken thread detector.
Background technology
Current transformer (CT) is typically used as current monitoring device in power system.CT may be used for detecting supply line
On size of current, carry out protecting or measuring being used for follow-up protection equipment.Generally, at secondary side, CT output
Detection electric current is transported to protection equipment by circuit, and the output of CT is sampled, and entered according to sampled result by protection equipment
The corresponding protection act of row.Here, if connecting the line failure (such as broken string) of CT output and protection equipment, then
Relevant protection equipment can be mistaken for supply line's fault and perform corresponding protection act, such as, trip.This has resulted in electricity
Force system maloperation.
The maloperation caused in order to avoid this CT broken string, industry proposes multiple CT wire break detection method.For difference
Protection type, it is possible to use different CT to break criterion.
The detection CT broken string criterion of a kind of differential protection being usually used in protecting time limit requirement the shortest includes burn out detection start-up criterion
Criterion two parts are confirmed with CT broken string.Burn out detection start-up criterion is: the only phase current of each in three-phase current is the biggest
In 0.2In(wherein InSize of current under normal circumstances) and the difference of circuit both sides phase current is respectively less than 0.1InShi Caiqi
Dynamic CT burn out detection.In other words, when this method only has electricity and fault-free on main line, just detection CT breaks.CT breaks
Confirm that criterion is: the only phase current of any one in three-phase current is less than 0.06InAnd the difference of circuit both sides phase current is more than
0.15InTime just confirm there occurs that CT breaks.This method needs to calculate I when detection every timen, and InCalculating generally need
Wanting 20ms, it substantially requires suitable with the protection time limit of differential protection.
A kind of CT broken string criterion of being usually used in distance protection is: if arbitrary phase current is less than 0.04In, and at least one
Phase current is constant and maximum phase current is less than 1.2In, then CT broken string is confirmed as.This method in order to by CT broken string and
Primary side leader cable open circuit makes a distinction and adds Rule of judgment.But, in power system because there is two or more power supply
And when there is oscillatory occurences, this detection method can None-identified goes out CT because of system oscillation (the most there is not constant phase current)
Broken string.
Another kind of common CT broken string criterion is to rely on the detection method of residual voltage and zero-sequence current.Specifically, this CT
Detection method is at zero-sequence current I0calculated> current start threshold and residual voltage U0calculatedSentence during≤voltage starting threshold
Break and occur in that CT breaks.The range of application of this detection method is narrower, and owing to it relies on residual voltage, by load
Impact, so the probability of generation tripping is of a relatively high.
In view of existing CT wire break detection method has as above defect, still need in prior art a kind of judgement simplicity and reliability
Higher CT wire break detection method.
Summary of the invention
In view of the drawbacks described above of prior art, propose a kind of CT wire break detection method and dress in an embodiment of the present invention
Put.The advantage using this method and apparatus is that computational methods are easy, thus confirmed in the short period of time be
No there occurs that CT breaks, another advantage is that and do not affected by system oscillation or uncompensated load.
CT wire break detection method includes according to an embodiment of the invention: at adjacent very first time window and the second time window
Interior current sampling data is integrated, and described current sampling data is to obtain by sampling the output of current transformer,
Thus obtain first integral value and the second integral value of corresponding second time window of corresponding very first time window, wherein, first, the
Equal in magnitude and the time window width of two time windows is less than 1/2 cycle of sample rate current；By first integral value divided by second integral
Value, obtains the first quotient；Judge whether described first quotient meets broken string criterion, if it is satisfied, then be judged as occurring in that electricity
Current transformer breaks.Wherein, described first, second time window width is preferably 1/4 cycle of sample rate current.
According to one embodiment of the invention, described judge that step includes: judge that whether described first quotient (Q) is more than the first threshold
Value (p), if it is greater, then be judged as occurring in that current transformer circuit supervision fail, wherein said first threshold (p) greater than about 6,
The most described first threshold is 10 ~ 20.
According to a further embodiment of the invention, described judge that step includes: judge described first quotient whether more than Second Threshold,
Wherein said Second Threshold is less than described first threshold and more than a maximum quotient of ideal, and the maximum quotient of this ideal is that ideal is adopted
The maximum of the business of integrated value in adjacent first, second time window under sample current waveform；And if described first quotient is more than
Described Second Threshold, the most described detection method also includes: obtain the previous zero passage sampled point before described second time window
Derivative；Obtain the derivative of each current sample point in described second time window, and therefrom obtain the maximum in each derivative
Value；Judge described derivative maximum whether more than the 3rd threshold value, the 3rd threshold value is about described previous zero passage sampled point
Derivative, if it is judged that for exceeding, then be judged as occurring in that current transformer circuit supervision fail.Wherein it is preferred to, described second
Threshold value (q) is of about 2.It is further preferable that wherein said Second Threshold (q) is n*1.963, wherein n is 1.2 ~ 1.3.
It addition, described 3rd threshold value is preferably n*Kzero-before, wherein n is 1.2 ~ 1.3.
According to a further embodiment of the invention, described integration step includes: in described very first time window and the second time window
Each, obtain each current sampling data in this time window；Accumulate all current sampling datas in described time window,
Obtain the described integrated value corresponding with this time window.
CT broken thread detector includes according to an embodiment of the invention: integration module, for respectively integration adjacent the
Current sampling data in one time window and the second time window, described current sampling data is by carrying out the output of current transformer
Sampling obtains, and thus obtains first integral value and the second integral value of corresponding second time window of corresponding very first time window, its
In, the equal in magnitude and time window width of first, second time window is less than 1/2 cycle of sample rate current；Seek quotient module block, use
In by first integral value divided by second integral value, obtain the first quotient；Judge module, it is judged that whether described first quotient meets
Broken string criterion, if it is satisfied, then be judged as occurring in that current transformer circuit supervision fail.Preferably, described first, second time window
Width is 1/4 cycle of sample rate current.
According to one embodiment of the invention, described judge module includes: the first judge module, is used for judging described first quotient
Whether more than first threshold, if it is greater, then be judged as occurring in that current transformer circuit supervision fail, wherein said first threshold is more than
About 6.
According to another embodiment of the present invention, wherein, described judge module also includes: the second judge module, it is judged that described
Whether one quotient is more than Second Threshold, and wherein said Second Threshold is less than described first threshold and more than a maximum business of ideal
Value, this ideal maximum quotient is the maximum of the business of integrated value in adjacent first, second time window under desired sampling current waveform；
And derivation module, for obtaining the derivative of the previous zero passage sampled point before described second time window, and obtain institute
State the derivative of each current sample point in the second time window, and therefrom obtain the maximum in each derivative；3rd judges mould
Block, be used for judging described derivative maximum whether more than the 3rd threshold value, the 3rd threshold value is of about the sampling of described previous zero passage
The derivative of point；Logical block, if the judged result of the second judge module and the 3rd judge module is for exceeding, then is judged as
Show current transformer circuit supervision fail.Preferably, described integration module is summation module, for adding up the electric current in corresponding time window
Sampled value.
Also proposed a kind of relay protection device in an alternative embodiment of the invention, it includes above-mentioned detection device.
Also proposed the storage medium that a kind of machine (such as computer) is readable in an alternative embodiment of the invention, storage is used for making
One machine performs the instruction of arbitrary above-mentioned detection method.Additionally, also proposed a kind of computer program, it comprises can hold
The computer-readable instruction of detection method described in row any of the above.
CT wire break detection method proposed in the embodiment of the present invention and detection device had not both relied on differential current signal the most not
Depend on residual voltage, so it can be used in differential protection, distance protection and current protective device.It is additionally, since this
Detection method amount of calculation employed in inventive embodiments is little, it is thus possible to judge in several milliseconds whether CT breaks,
Relative to existing algorithm based on Fourier transformation, there is the advantage that obvious response speed is fast.Additionally, due to the present invention is real
Executing the detection algorithm proposed in example is not to rely on merely whether certain phase current is stablized to judge that CT breaks, thus this judgement
Method is not affected by system oscillation or unbalanced load, thus the reliability judged is high.Furthermore, the embodiment of the present invention carries
The detection method gone out can detect for the most every phase current, it is also possible to detects while multiphase current, thus
Range of application width, flexibly and easily.It addition, the method proposed in the embodiment of the present invention has taken into full account what CT zero crossing broke
Situation, even if thus occur CT zero crossing broken string, remain to reliably working.
Accompanying drawing explanation
The purpose of the present invention, feature, feature and advantage be will become apparent from by the detailed description below in conjunction with accompanying drawing.
Wherein:
Fig. 1 shows the preferable sample waveform of a kind of CT output electric current；
Fig. 2 A shows the situation of the sample waveform of adjacent two 1/4 cycle scanning computed tomographies after taking absolute value CT sampled value；；
Fig. 2 B and Fig. 2 C schematically illustrates and at non-zero crossing and zero crossing, CT broken string occurs after taking absolute value sampled value
Sample waveform；
Fig. 3 shows the flow chart of CT wire break detection method according to an embodiment of the invention；
Fig. 4 A and Fig. 4 B respectively illustrates the testing result of the situation that breaks for Fig. 2 B and Fig. 2 C two kinds；
Fig. 5 schematically illustrates the judge process of CT broken string in accordance with another embodiment of the present invention；
Fig. 6 A and Fig. 6 B shows the structured flowchart of CT broken thread detector according to an embodiment of the invention.
Detailed description of the invention
In order to quickly determine that and whether occur that CT breaks, following example of the present invention propose by comparing phase
The integrated value of the adjacent sampled point in two time windows (i.e. part cycle) judges the method whether CT breaks, the most often
Individual time window is less than 1/2 cycle, the most preferably 1/4 cycle.Although below as a example by the time window of two continuous print 1/4 cycles
Describe embodiments of the invention, but it will be understood by those skilled in the art that the size of two adjacent time windows is permissible
It is adjusted according to actual needs.Such as, under conditions of being enough to distinguish main line cable break and CT broken string, can be by every
The width appropriateness of individual time window expands or shrinks, for example with two continuous print 1/5 cycles or 2/7 cycle etc..Below will knot
Close accompanying drawing and describe the specific embodiment of the CT wire break detection method that the present invention proposes in detail.
Fig. 1 schematically illustrates in power system the ideal waveform obtained after a cross streams current sample.Shown in Fig. 1
Example in, it is assumed that each cycle sampling 20 points.If the frequency of power system is 50Hz, then sample frequency will be
1KHz, i.e. sampling interval are 1ms.Certainly, in actual frequency-tracking system, current sample frequency can be adaptively
Change with the frequency of power system, rather than be fixed in the frequency shown in Fig. 1.
Ideal waveform shown in Fig. 1 is sinusoidal wave.In the example depicted in figure 1, the 1st sampled point of a cycle is from mistake
Zero point starts to start at, and terminates to zero crossing that is the 21st sampled point that this cycle terminates.Fig. 1 schematically illustrates phase
Two adjacent cycles, the i.e. the 1st ~ 41 sampled point, wherein the 1st, 11,21 and 31 be zero crossing.It practice, electric current
One cycle of waveform can be started at from any one sampled point, until the 21st sampled point started from Fixed Initial Point terminates.
In theory, CT broken string can occur any one place in such as shown in Fig. 1 a cycle.It is to say, CT
Broken string can occur at non-zero crossing, it is possible to occurs at zero crossing.Fig. 2 A ~ 2C shows and CT broken string does not occurs and occurs
The oscillogram of the current sample of CT broken string, wherein only only accounts for the size of current amplitude in Fig. 2 A ~ 2C, thus will originally
The current waveform of negative semiaxis moves positive axis.
Fig. 2 A shows the current waveform not occurred when CT breaks.As shown in Figure 2 A, when CT circuit is normal, as
The integration of current sampling data in more adjacent two 1/4 cycles of fruit, then it is seen that the integrated value phase of adjacent two 1/4 cycles
Difference is very few.Such as, shown in Fig. 2 A, if current sampling data in two 1/4 cycles that sampled point scanning is adjacent one by one
Integration, then, it is seen that under ideal waveform in adjacent two 1/4 cycles current sampling data integration maximum differ one times, the most right
In situation shown in Fig. 2 A, the integrated value of 1/4 cycle is the largest of about 1.963 times of the integrated value of later 1/4 cycle.
Fig. 2 B and Fig. 2 C respectively illustrates the situations that break at non-zero crossing and break at two kinds of CT of zero crossing broken string.?
In Fig. 2 A, it is assumed that CT broken string occurs at non-zero crossing, such as broken string occurs, thus from the 25th after the 24th sampled point
The value of follow-up all sampled points that individual sampling is lighted is zero.In fig. 2b, it is assumed that CT broken string occurs at zero crossing, such as
21st sampled point, the value of the follow-up all sampled points thus lighted from the 22nd sampling is zero.
From the CT broken string situation shown by Fig. 2 B and Fig. 2 C, after CT breaks, current sampling data can decline rapidly
Be zero, such as, once CT broken string occurs in the example of Fig. 2 A and 2B, next sampled value is with regard to vanishing.But, right
For general main line electric discontinuity of cable, due to primary side distribution capacity, the existence of distributed inductance, though main line open circuit,
Electric current will also pass through a relatively slow process and decays to zero, and this process is generally higher than 1/4 cycle.Thus, the present invention
If inventor propose preferably to compare the integration of sampled value in former and later two 1/4 adjacent cycles, whether can judge
There occurs that CT breaks.
Fig. 3 schematically illustrates a kind of CT wire break detection method based on above-mentioned thought.In the embodiment shown in fig. 3,
Testing process is from the beginning of step S310.In step S310, first calculate adjacent two 1/4 cycles the (that is, the one 1/4
Cycle and the 2nd 1/4 cycle) integration of interior sampled value, thus obtain two integrated values S1 and S2, wherein integrated value S1 pair
Should be in the one 1/4 cycle, integrated value S2 corresponds to the 2nd 1/4 cycle.And then, in step s 320, with S1 divided by
S2, obtains a quotient Q.In step S330, quotient Q is compared with predetermined threshold decision condition, if
Comparative result is that quotient Q meets this Rule of judgment, then be judged as in step S350 that CT breaks, and otherwise flow process enters into
Step S340, is i.e. moved rearwards by the two 1/4 cycle time window, is then return to step S310, continues follow-up sampled point
Repeat this detection method.
In the flow process shown in Fig. 3, those skilled in the art can use many in conjunction with the characteristic of CT broken string in step S330
Plant different criterions and judge whether CT breaks.Such as, in step S330, it is judged that quotient Q is more than one the most relatively
Big predetermined threshold p, such as p can be much larger than the number (in view of under ideal waveform, quotient Q is about 1.963) of 2,
Preferably p is more than 6, and more preferably p is about in the range of 10 ~ 20.
When Fig. 4 A-4B shows p=12, detection method realizes situation.Broken string situation shown in Fig. 4 A is identical with Fig. 2 B,
I.e. broken string occurs at non-zero crossing.As shown in Figure 4 A, two adjacent 1/4 cycle detection window points of scanning sample successively.
Starting point is from the beginning of the 1st sampled point, according to step S310, first calculates and includes that the one 1/4 cycle is interior (between front 5 samplings
Every) area of the one 1/4 cycle in integrated value S1(of sampled point i.e. figure), and calculate include the 2nd 1/4 cycle in adopt
The area of the 2nd 1/4 cycle in integrated value S2(of sampling point i.e. figure).Then, Q=S1/S2 is calculated in step s 320.
And then, in step S330-1, it is judged that whether Q is more than p(p=12).In original position, it is clear that Q=1, Q are less than p.
Then, two 1/4 cycle time windows are moved rearwards by a sampling interval, and the starting point of the i.e. the 1st cycle is from the 2nd point
Start, and repeated execution of steps S310, S320 and S330-1.When the detection window of two 1/4 cycles moves to such as Fig. 4 A
During shown position A, can calculate Q and be about 3.2, it has been above normal maximum 1.963.When two 1/4
The time window of cycle, when position A moves a sampling interval the most again, can calculate Q and tend to infinite, at this moment
Q exceeds well over 12, thus can judge that CT occurs in that broken string at the 30th, only identifies CT broken string in 6ms.
Broken string situation shown in Fig. 4 B is identical with Fig. 2 C, i.e. broken string occurs at zero crossing.Process as described above, uses phase
Two adjacent 1/4 cycle time window point by point scanning sampled values.When the time window of two 1/4 cycles moves to shown in Fig. 4 B
Position B time, Q can be calculated and be about 14, therefore Q is more than 12, thus can judge that CT occurs in that at the 25th
Broken string, the most only identifies CT broken string in 5ms.
In another embodiment, for the ease of judging the situation occurring broken string at non-zero crossing, step S330 is further
Including step as shown in Figure 5.Specifically, as it is shown in figure 5, work as and find that in step S330-1 the Q calculated is little
When p, perform step S530-2 further, i.e. judge that whether Q is more than another predetermined threshold q.This predetermined threshold q
Being one and less than threshold value p but be more than the value of 1.963, such as q can be about 2.It is further preferable that q=n*1.963, its
Middle n is the hysteresis index of an experience, preferably 1.2 ~ 1.3, it is used for preventing judged result in Near Threshold saltus step repeatedly.With
This, or before or after step S530-2, in step S530-3, calculates current 2nd 1/4 week further simultaneously
In ripple each sampled point derivative Kx(or, the slope of sampled point), and obtain before the 2nd 1/4 cycle upper
The derivative Kzero-before of one zero crossing.Then, in step S530-4, judge whether exist in the 2nd 1/4 cycle
At least one Kx, it meets Kx > Kzero-before.It is further preferable that judge whether at least one Kx, it is full
Foot Kx > n*Kzero-before, wherein n is empirical value, preferably n=1.2 ~ 1.3.If in step S530-4 and step
In S530-2, judged result is and is, then show to occur in that CT breaks, and is otherwise judged as normal, continues executing with step S340.
Method shown in Fig. 5 is equally applicable to the broken string situation shown in Fig. 4 A.As shown in Figure 4 A, when two 1/4 week
When ripple moves to the position A shown in Fig. 4 A, the Q-value calculated in step S320 is of about 3.2, in step S330-1
Judge that Q is not more than threshold value p, and then judge that Q is more than threshold value q in step S530-2, q=1.3*1.963=2.55,
Here empirical value n is chosen for 1.3.Then, in step S530-3, obtain leading of previous zero crossing (the i.e. the 21st point)
Number (such as, slope), and calculate the derivative (such as, slope) of each sampled point in the 2nd 1/4 cycle.Then in step S530-4
In judge the derivative (such as, slope) of the 25th derivative more than the 21st.Thus, the judgement knot of step S530-4
Fruit is yes.Finally, due to finding that the judged result of step S530-2 and step S530-4 is is thus to judge to occur
CT broken string.So, i.e. can detect that CT breaks at the 29th, in 5ms, the most only identify CT broken string.
Integration step shown in figure 3 above and Fig. 5 can also use summing mode to substitute.Such as the one 1/4 week
Ripple or the 2nd 1/4 cycle, obtain each current sampling data in this 1/4 cycle, then accumulate the institute in this 1/4 cycle
There is current sampling data, obtain the integrated value corresponding with this 1/4 cycle.So, amount of calculation can reduce further.
Method shown in figure 3 above and Fig. 5 can realize with software, it is also possible to realizes with hardware, or uses soft or hard
The mode that part combines realizes.Fig. 6 A and Fig. 6 B schematically illustrates hardware configuration frame according to an embodiment of the invention
Figure.
As shown in Figure 6A, the equipment for realizing CT burn out detection includes: integration module 610, seeks quotient module block 620 and sentences
Disconnected module 630.Integration module 610 is for respectively at adjacent time window (the such as the 1st cycle and the 2nd 1/4 cycle)
The value of the interior current sample point exporting this current transformer is integrated, and thus obtains the first of corresponding one 1/4 cycle
Integrated value S1 and second integral value S2 of corresponding 2nd 1/4 cycle.Seek quotient module block 620, for first integral value S1 being removed
With second integral value S2, obtain the first quotient Q.Judge module 630, is used for judging whether described first quotient meets broken string
Criterion, if it is satisfied, then be judged as occurring in that current transformer circuit supervision fail.
Fig. 6 B particularly illustrates a kind of preferred implementation module 630-1 of judge module.As shown in Figure 6B, it is judged that module
630 include the first judge module 631, and it judges whether the first quotient Q is more than first threshold p, if greater than then representing broken string,
And will determine that result be delivered to OR(or) logical block 636, wherein first threshold p is greater than 6, preferably more than 10,
Or more preferably p is 10 ~ 20.
Preferably, it is judged that module 630 may also include the second judge module 632 and judges that whether the first quotient Q is more than Second Threshold
P, wherein Second Threshold q is less than first threshold Q but more than the maximum of Q-value under ideal waveform.Preferably, q=n*1.963,
Wherein n=1.2 ~ 1.3.The judged result of the second judge module 632 send into AND (with) logical block 635.Derivation module 633
Obtain the derivative (or slope) of each current sample point in the 2nd 1/4 cycle, and therefrom obtain each derivative (or slope)
In maximum, obtain the derivative K of previous zero current cross sampled point before the 2nd 1/4 cycle simultaneouslyzero-before.The
Three judge modules 634 judge described derivative maximum whether more than the 3rd threshold value, the 3rd threshold value is about Kzero-before, excellent
Selection of land the 3rd threshold value is n*Kzero-before, wherein n=1.2 ~ 1.3.The judged result of the 3rd judge module is also fed into AND
(with) logical block 635.When from second and the 3rd the result of judge module be "Yes" time, AND logical block 635
It is output as 1.OR logical block 636 in the output of the first judge module and AND logical block arbitrary for "Yes" time,
Confirm to occur in that CT breaks.
Fig. 6 A and 6B shows the hardware block diagram of the CT broken thread detector that the present invention proposes with being merely exemplary.According to
Actual demand and the common knowledge of this area, those skilled in the art can also use various ways to realize this CT broken string
Detection device.Such as, the modules in Fig. 6 A and 6B can carry out combination in any.The most such as, AND logical block
Can be replaced by other logical combinations with OR logical block.These changes are all that those skilled in the art are obvious.
Additionally, the detection device shown in Fig. 6 A and Fig. 6 B can be applied in the relay protection system of arbitrary adaptation.
Present invention also offers the storage medium that a kind of machine (such as computer) is readable, storage is used for making a machine perform such as this
The instruction of the fuzz testing method described in literary composition.The present invention also provides for a kind of computer program, and it comprises can perform described obscuring
The computer-readable instruction of method of testing.
Specifically, it is provided that be furnished with system or the device of storage medium, store on the storage medium and realize above-mentioned reality
Execute the software program code of the function of any embodiment in example, and make this system or device computer (or CPU or
MPU) read and perform the program code being stored in storage medium.
In this case, the program code itself read from storage medium can realize any one embodiment above-described embodiment
Function, therefore the storage medium of program code and storage program code constitutes the part of the present invention.
For provide the storage medium embodiment of program code include floppy disk, hard disk, magneto-optic disk, CD (as CD-ROM,
CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), tape, non-volatile memories
Card and ROM.Selectively, can be by communication network download program code from server computer.
Further, it should be apparent that, not only by the program code performed read-out by computer, and base can be passed through
Instruction in program code makes the operating system etc. of calculating hands-operation complete practical operation partly or completely, thus real
The function of any one embodiment in existing above-described embodiment.
It will be appreciated by those skilled in the art that each embodiment disclosed above can be in the case of without departing from invention essence
Making various changes and modifications, these change and amendment all should fall within the scope and spirit of the invention.Therefore, the present invention
Protection domain should be defined by the appended claims.
Claims (18)
1. the detection method of a current transformer circuit supervision fail, it is characterised in that including:
Being integrated the current sampling data in adjacent very first time window and the second time window, described current sampling data is to pass through
The output of current transformer is sampled and obtains, thus obtain the first integral value and corresponding second of corresponding very first time window
The second integral value of time window, wherein, the equal in magnitude and time window width of first, second time window is less than sample rate current
1/2 cycle；
By first integral value divided by second integral value, obtain the first quotient；
Judge whether described first quotient meets broken string criterion, if it is satisfied, then be judged as occurring in that current transformer circuit supervision fail.
2. detection method as claimed in claim 1, wherein, described first, second time window width is sample rate current
1/4 cycle.
3. detection method as claimed in claim 1 or 2, wherein, described detection method also comprises the steps:
Judge whether described first quotient is more than first threshold, if it is greater, then be judged as occurring in that current transformer circuit supervision fail,
Wherein said first threshold is more than 6.
4. detection method as claimed in claim 3, wherein, described detection method also comprises the steps:
Judging whether described first quotient is more than Second Threshold, wherein said Second Threshold is less than described first threshold and more than one
Individual preferable maximum quotient, this ideal maximum quotient is integrated value in adjacent first, second time window under desired sampling current waveform
The maximum of business；And
If described first quotient is more than described Second Threshold, the most described detection method also includes:
The derivative of the acquisition previous zero passage sampled point before described second time window；
Obtain the derivative of each current sample point in described second time window, and therefrom obtain the maximum in each derivative；
Judge described derivative maximum whether more than the 3rd threshold value, the 3rd threshold value is the derivative of described previous zero passage sampled point,
If it is judged that for exceeding, then be judged as occurring in that current transformer circuit supervision fail.
5. detection method as claimed in claim 4, wherein said Second Threshold is 2.
6. detection method as claimed in claim 4, wherein said Second Threshold is n × 1.963, and wherein n is 1.2～1.3.
7. detection method as claimed in claim 4, wherein said 3rd threshold value is n × Kzero-before, wherein n is 1.2～1.3.
8. detection method as claimed in claim 3, wherein said first threshold is 10～20.
9. detection method as claimed in claim 1, wherein, described detection method also comprises the steps:
For each in described very first time window and the second time window,
Obtain each current sampling data in this time window；
Accumulate all current sampling datas in described time window, obtain the described integrated value corresponding with this time window.
10. the detection device of a current transformer circuit supervision fail, it is characterised in that including:
Integration module (610), the current sampling data in the very first time window adjacent for integration respectively and the second time window, institute
Stating current sampling data is to obtain by sampling the output of current transformer, thus obtains the of corresponding very first time window
One integrated value and the second integral value of corresponding second time window, wherein, the equal in magnitude and time window of first, second time window
Width is less than 1/2 cycle of sample rate current；
Seek quotient module block (620), be used for first integral value divided by second integral value, obtain the first quotient；
Judge module (630), it is judged that whether described first quotient meets broken string criterion, if it is satisfied, then be judged as occurring in that
Current transformer circuit supervision fail.
11. detect device as claimed in claim 10, and wherein, described first, second time window width is sample rate current
1/4 cycle.
The 12. detection devices as described in claim 10 or 11, wherein, described judge module (630) including:
First judge module (631), is used for judging whether described first quotient is more than first threshold, if it is greater, then judge
For occurring in that current transformer circuit supervision fail, wherein said first threshold is more than 6.
13. detect device as claimed in claim 12, and wherein, described judge module (630) also includes:
Second judge module (632), it is judged that whether described first quotient is more than Second Threshold, and wherein said Second Threshold is less than
Described first threshold and more than a preferable maximum quotient, this ideal maximum quotient is under desired sampling current waveform adjacent the
One, the maximum of the business of integrated value in the second time window；And
Derivation module (633), for obtaining the derivative of the previous zero passage sampled point before described second time window, and
Obtain the derivative of each current sample point in described second time window, and therefrom obtain the maximum in each derivative；
3rd judge module (634), be used for judging described derivative maximum whether more than the 3rd threshold value, the 3rd threshold value is institute
State the derivative of previous zero passage sampled point；
Logical block (635), if the judged result of the second judge module (632) and the 3rd judge module (634) is super
Cross, be then judged as occurring in that current transformer circuit supervision fail.
14. detect device as claimed in claim 13, and wherein said Second Threshold (q) is n × 1.963, and wherein n is
1.2～1.3.
15. detect device as claimed in claim 13, and wherein said 3rd threshold value is n × Kzero-before, wherein n is
1.2～1.3.
16. detect device as claimed in claim 12, and wherein said first threshold is 10～20.
17. detect device as claimed in claim 10, and wherein, described integration module (610) is summation module, is used for
Current sampling data in cumulative corresponding time window.
18. 1 kinds of relay protection devices, it is characterised in that include the detection device as described in arbitrary in claim 10-17.
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| WO2020026163A3 (en) * | 2018-07-31 | 2020-03-12 | Abb Schweiz Ag | A method and a device for supervision of a voltage transformer |
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