CN101916989B - Method for distinguishing effectiveness two-time continuous sampling values of electric power system - Google Patents
Method for distinguishing effectiveness two-time continuous sampling values of electric power system Download PDFInfo
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Abstract
The invention relates to a method for distinguishing effectiveness two-time continuous sampling values of an electric power system, which comprises the steps of: establishing a saltus threshold formula of sampling values of curved continuous points and a saltus threshold formula of sampling values of curved discontinuous points, ensuring that the sampling points with saltus values exceeding the saltus threshold of the sampling values of the curved continuous points become the discontinuous points of a curved line, but are used as effective sampling values of the curved line, wherein the saltus values are less than the saltus thresholds of the sampling values of the curved discontinuous points; and analyzing the application of the limit of the minimum precision threshold of a mutual inductor and the periodical characteristic of a current voltage signal of the mutual inductor to the process of judging the effectiveness of the sampling values. On the basis, a delay 3-point continuous effective judgment method and a delay-free 3-point continuous effective judgment method of the sampling values are invented, the right reliability of sampled data is ensured, operation resistance and misoperation of a protection measuring and controlling device and the like are avoided, and the safe and stable operation of the electric power system is protected.
Description
Technical field
The present invention relates to a kind of method of discrimination of electric power system double sampling data validity, particularly a kind of real-time identification method of abnormal sample value.
Background technology
What widely popularize at national grid is that intelligent substation was an one of which important node during the strong intelligent grid of backbone network was built with the ultra high voltage.Information sharing is a key character of intelligent substation, comprises just that wherein sampled data is shared.Its implementation procedure is that the data sampling process is controlled by merge cells (MU), and by electric mutual inductor or MU completion acquisition tasks, sampled data gathers, organizes bag and transmission through MU, supplies multiple bay device uses such as protective device.Because the data acquisition transmission course is complicated; For guaranteeing to share the correct reliable of sampled data; Avoid invalid data to cause protective device malfunction or tripping; Cause unnecessary power outage or cause the accident extension, jeopardize safe operation of power system, the validity that in " merge cells technical conditions " (revised draft) of in April, 2010 promulgation, spells out the sampled value of its forwarding of MU reply is made judgement.
Do not see as yet at present and can be used for protecting the have relatively high expectations public reported of relevant sampled value validity determination methods of occasion of measure and control device and other real-times.To be current/voltage have very big difference at the normal operation of system and fault interval to its reason that (with the current component is example; During its normal operation is the less first-harmonic sine curve of amplitude; After the fault not only amplitude have the growth of tens times or hundreds of times; The harmonic component and the DC component that also can contain a large amount of decay, curve shape are very complicated), the normal sampled value when making the abnormal sample value and the system failure is difficult to distinguish.A large amount of bad datas that adopt detect discrimination method in the Power system state estimation; Referring to Zhang Yongchao. " the electric power system bad data detects and discrimination method research ". Southwest Jiaotong University's graduate degree paper; 2006, can't be applied to the judgement of abnormal point numerical certificate of double sampling value that wavy curve is the current/voltage of principal character with the sine because of only being suitable for linear system.Can screen the abnormal sample point through curve fit on the least squares theory; But it needs the approximate fitting function of known tested curve; This is difficult to accomplish in system failure transient process; And be the continuous a plurality of abnormal sample values of identification, must adopt very long data window, the processing that brings thus time-delay and huge amount of calculation are real-time system and can't stand.Patent of invention " method for processing sampling value of digitalization protection test control apparatus " (applicant: Zhou Bin, Huang Guofang etc.The number of applying for a patent: propose 200810196354) with the size of sampled value and the method for variable quantity judgement sampled value validity; Belong to overflow filter method and sudden change amount filter method commonly used in the noise processed in essence; These methods are owing to can not scientifically provide sampled value amplitude threshold or variable quantity threshold; For avoiding the erroneous judgement of normal sampled value under the system failure state, bigger amplitude threshold or variable quantity threshold can only be set, so only can detect a small amount of typical exceptional value.Li Chun; Deng, in " based on the protective relaying device electromagnetic interference software protecting fast algorithm research of small echo ", Electric Power Automation Equipment; 2008 11 phases; In the improved fast algorithm based on the S conversion has been proposed, detect the singular point in the signal through selecting suitable difference threshold value, can to detect this singular point be normal fault-signal or receive interference signal to analyze near the singular point the positive negative characteristic of difference value.But it does not provide the choosing method of threshold value, and does not fit into the detection examination of continuous bad data, exists the data computation amount big simultaneously, and the device level of hardware is required problems such as height.
Summary of the invention
The present invention wants the technical solution problem to be: the above-mentioned deficiency that overcomes prior art; The invention provides method for distinguishing effectiveness two-time continuous sampling values of electric power system; It includes 3 continuous effective diagnostic methods of band time-delay of a kind of sampled value, and 3 continuous effective diagnostic methods of a kind of nothing of sampled value time-delay, guarantees the correct reliability of sampled data; Avoid protecting the tripping or the malfunction of measure and control device etc., the operation of protection power system safety and stability.
In order to solve above technical problem; 3 continuous effective diagnostic methods of band time-delay of sampled value provided by the invention; It is characterized in that: be provided with the data buffer zone that length equals 3, sampled value moves into, shifts out the data buffer zone successively with FIFO ground form, and concrete method of discrimination may further comprise the steps:
A, to moving into 3 continuous sampling value f (x in the data buffer zone
K-2), f (x
K-1), f (x
k) carry out real-time judge, f (x
K-2), f (x
K-1), f (x
k) represent the sampled value of k-2, k-1, k sampled point, x respectively
kRepresent the sampling instant of k sampled point, if said 3 point sampling values all less than the minimum Seiko threshold of instrument transformer, the interim state of then said 3 point sampling values is set to effectively, and goes to step D, otherwise goes to step B;
B, judge whether inequality (1) is set up, if this inequality is set up, the interim state of said 3 point sampling values is set to effectively, and goes to step C;
In the inequality (1), Δ f (x
K-1)=f (x
k)-f (x
K-1),
ε
1For curve can be led down differential errors threshold, ε continuously
1=m
1A
1(ω T
s)
2, m
1Be first safety factor, m
1Span be [2,7], A
1Be the maximum fundamental voltage amplitude of system power voltage, ω is specified angular frequency, and Ts is the time in sampling interval;
C, if the data buffer zone in first sampled value f (x
K-2) interim state be effectively, sampled value f (x
K-2) be less than or equal to sampled value maximum threshold, and it is not the constant non-zero constant of continuous 1/2 cycle, then keeps this sampled value f (x
K-2) interim state and go to step D, otherwise sampled value f (x
K-2) interim state be set to invalid and go to step D;
If D sampled value f is (x
K-2) interim state be effectively, then judge this sampled value f (x
K-2) effectively, otherwise this sampled value f (x
K-2) invalid.
The theoretical foundation of method step A is following:
Though all kinds of current-voltage transformers in the electric power system are because operation principle and implementation method different; It possesses the accurate working point of distinctive minimum (being called for short minimum Seiko threshold); But their the performance situation under the accurate working point of minimum is roughly the same, and promptly sampled value is main with background noise all, and amplitude is little; Randomness is strong, shows very strong non-linear.For guaranteeing the validity of sampled value judged result in the case, when continuous 3 point sampling values during, can not carry out the validity of sampled value and judge all less than the minimum Seiko threshold of instrument transformer, think that simply sampled data is effective.
The absolute value and the differential errors threshold ε of the difference of forward and backward difference through median sample value among the step B
1Compare, judge the validity of sampled point.
According to electric power system general knowledge, when normally moving, can think only has non-decay fundametal compoment existence in the system, and current/voltage is the smooth curve that can lead continuously.When system breaks down or breaker operator is arranged; Because the flip-flop of network configuration; The current/voltage of system will be redistributed, and direct current that might occur decaying and each harmonic component, and can there be transition in various degree in the charge value at difference place in the system; When this transition value is big, will make its wavy curve occur discontinuous point herein.During like system's generation earth fault, earth point voltage drops to about zero volt from approximate rated value is instantaneous, and the transition of transient voltage value is obvious before and after the fault.
Except that discontinuous point, the wavy curve of electric power system current/voltage can be led at other places, arbitrfary point continuously, and the same segmentation of its derivative is continuous.Whether effectively this characteristic provides theoretical foundation for what we judged sampled value; Promptly generally speaking; But satisfy the described segmentation of electric power system current/voltage universal expression formula derived function continuously like sampled value, or can be led continuously by the curve segmentation that sampled value constitutes, then sampled value is effective.But because the function expression of electric weight waveform is difficult to try to achieve in real time the validity of each sampled value of check in real time that inconvenience is used.Because of sampled data is a discrete magnitude, whether the judgement of directly using can be led by its curve that constitutes continuously again, and then whether effectively same existence is certain difficult to judge a certain sampled value.
According to mathematical knowledge, function f (x) is at x
kPoint can be led, and then its left and right derivative at this some place exists and equates.For discrete sampled data, when abundant hour of sampling step length, neighbouring sample point was through forward difference quotient and backward difference quotient acquisition before and after its left and right derivative at certain some place can be used.Because the sampling period equates, the judgement that the left and right derivative of certain point sampling value equates and then can be converted into its forward and backward difference and equate to carry out.Consider sampling error and wave form varies situation, allow to exist certain deviation between the forward and backward difference of each point sampled value, the deviate of this permission is threshold ε
1, threshold ε
1Curve can be called as and the differential errors threshold can be led down continuously.Based on electric power system current/voltage universal expression formula f (t), can get
In the formula, n is a harmonic number, p
nRatio for nth harmonic amplitude and fundamental voltage amplitude.So can make ε
1=m
1A
1(ω T
s)
2, m1=∑ n wherein
2p
n, m
1Be first safety factor, the percentage decision that its value accounts for first-harmonic by various harmonic waves or DC component in the failure process, can be between 2～7 under the normal condition value.Generally speaking, but m
1Get 3,, should according to circumstances suitably get higher value for the abundant application places of harmonic wave.A
1Be the maximum fundamental voltage amplitude of system power voltage, determine by system operation mode.Be the convenience of calculation of adjusting, A
1Can be simply alternative with the multiple value of electric current voltage rating, get 20 times rated value like current component, component of voltage is got 2 times rated value.
By ε
1=m
1A
1(ω T
s)
2, curve can be led down differential errors threshold ε continuously
1With the sampling interval time T
sSquare be directly proportional, because of time in sampling interval and sample frequency are inversely proportional to, so but to same section continuous lead curve, its data sampling rate is high more, it is just low more that curve can be led down the differential errors threshold continuously, also low more to the serious forgiveness of noise and abnormal disturbances.As being the system of 4kHz, work as m to sample rate
1=3 o'clock, the maximum disturbance point amplitude sudden change amount that allows was about
Promptly be about 1% of maximum fundamental voltage amplitude.
Thus it is clear that, m
1Value need some empirical and skills, but also have certain rules property, promptly harmonic wave is abundant more, harmonic number is high more, m
1Value is just big more.Those skilled in the art understand m
1Span and Changing Pattern thereof after, can easier estimate m
1, and satisfy requirement of engineering.Even estimate that first deviation is bigger, also can be through attempting and test the estimated value that obtains near theoretical value for several times.m
1Except relying on empirical estimating, can also pass through formula m
1=∑ n
2p
nAccurately try to achieve.
Like this, can lead differential errors threshold ε down continuously at known curve
1The time; But the validity of certain section continuous lead curve sampled value can be judged through following method: for 3 neighbouring sample point data; If the forward and backward difference value of point sampling value satisfies inequality (1) requirement wherein, then they are the efficiently sampling value, otherwise must have some sampled values invalid.Because the method used 3 neighbouring sample point data, and according to the validity of the judgement of the property led the continuously sampled value of curve, so can simple be called 3 continuous effective diagnostic methods of sampled value.
Because the wavy curve segmentation of electric power system current/voltage can be led continuously, so step B can judge the validity of sampled value through 3 continuous effective diagnostic methods of sampled value.
Among the step C,, when sampled value remains unchanged for a long time, think that then the mutual inductor sample loop is unusual according to the periodicity characteristics of current/voltage.As for sampled value continuously more than or equal to the full certain hour (1/2 cycle) of value partially, or (1/2 cycle) keeps a certain nonzero value (greater than the minimum Seiko threshold of instrument transformer) constant within a certain period of time, thinks that sampling circuit is unusual, it is invalid to put sampled value.
In 3 continuous effective diagnostic methods of band time-delay of this sampled value; Except that first and second sampled point; Each sampled point that moves into buffering area successively will experience the validity deterministic process 3 times, and normal therebetween sampled value has at least and once is judged to effectively, and unusual transition sampled value then can not be judged to effective.This determination methods postpones the judged result that 2 sampled points have provided sampled value validity, and deterministic process is main according to 3 continuous effective diagnostic methods, so can simple be called 3 continuous effective diagnostic methods of band time-delay of sampled value.
In addition, 3 continuous effective diagnostic methods of the nothing of sampled value provided by the invention time-delay is characterized in that step comprises:
A, if current sampled value f (x
k) more last point sampling value f (x
K-1) variable quantity become threshold more greater than curve discontinuous point sampled value, then declare current sampled value f (x
k) invalid, otherwise go to step b, f (x
k), f (x
K-1) for representing the sampled value of k, k-1 sampled point, x respectively
k, x
K-1Represent the sampling instant of k, k-1 sampled point respectively;
B, to the slow f (x of up-to-date 3 point sampling data
K-2), f (x
K-1), f (x
k) carry out real-time judge, f (x
K-2) sampled value of expression k-2 sampled point, x
K-2Represent the sampling instant of k-2 sampled point, if said 3 point sampling values are all less than the minimum Seiko threshold of instrument transformer, then with current sampled value f (x
k) interim state be set to effectively, and go to step f, otherwise go to step c;
If c is current sampled value f (x
k) greater than sampled value maximum threshold, then judge current sampled value f (x
k) invalid, otherwise go to steps d;
D, judge whether said 3 point sampling values satisfy inequality (1),, then go to step f, otherwise go to step e if this inequality is set up;
In the inequality (1), Δ f (x
K-1)=f (x
k)-f (x
K-1),
ε
1For curve can be led down differential errors threshold, ε continuously
1=m
1A
1(ω T
s)
2, m
1Be first safety factor, m
1Span be [2,7], A
1Be the maximum fundamental voltage amplitude of system power voltage, ω is specified angular frequency, and Ts is the time in sampling interval;
E, judge whether inequality (2) is set up,, then go to step f, otherwise judge current sampled value f (x if inequality (2) is set up
k) be invalid;
In the inequality (2),
ε
1Be the transition threshold of curve continuity point sampled value, ε
2=m
2A
1ω T
s, m
2Be second safety factor, m
2Span be [2,4];
If f is current sampled value f (x
k) be not the constant non-zero constant of continuous 1/2 cycle, then declare current sampled value f (x
k) effectively, otherwise declare current sampled value f (x
K-2) invalid.
Because 3 continuous effective diagnostic methods of the nothing of sampled value time-delay can provide the validity judged result of sampled value in real time, so it can be applicable to the occasion that real-time is had relatively high expectations.
3 continuous effective diagnostic methods of nothing time-delay of sampled value can be invalid with discontinuous point and 1 to 2 continuous sampling value erroneous judgement thereafter.For reducing the quantity of invalid sampled point, can in its deterministic process, increase the sampled value variable quantity and judge, promptly to the data of cancelling, if its more last point sampling value variable quantity less than the transition threshold of curve continuity point sampled value, is then mended and declared that it is effective.Open sampled value variable quantity Rule of judgment can be when the erroneous judgement of minimizing valid data be invalid, and distortion data erroneous judgement that may amplitude is less effectively.So whether it uses and should be determined by actual demand.
Traditional electromagnetic current transducer (TA) receives the restriction of operation principle and practical applications; Have the magnetic saturation phenomenon, its characteristic feature is that the progress of disease characteristic of instrument transformer will get into the inelastic region, and along with the intensification of degree of saturation; Secondary progress of disease value will sharply reduce, until arriving zero.Because the periodicity of primary current, the magnetic saturation phenomenon also can periodically occur, and on its double sampling value curve, then shows as the discontinuous point that a large amount of periodicity occur.As not screening sampled data, correspondingly have a large amount of invalid sampled points and periodically occur with there being 3 continuous effective diagnostic methods of time-delay.The invalid data that occurs in this process should be looked the magnetic saturation phenomenon its concrete influence is decided the influence of defencive function.Like differential fast tripping protection, for avoiding malfunction need take the locking measure, invalid data still helped it and takes the locking measure except that no any negative effect when TA was saturated.But the protection of adjusting the distance, TA is saturated in the failure process can not cause protecting malfunction, and under no special processing situation, the appearance of invalid data will cause protecting locking, influence protection responsiveness.Therefore, when using 3 continuous effective diagnostic methods of nothing time-delay, should open sampled value variable quantity Rule of judgment according to circumstances selectively, be beneficial to protect action message.
Electronic mutual inductor is because no magnetic saturation phenomenon; The true discontinuous point of i-v curve can only appear at the moment of system network architecture or changes of operating modes; The probability that occurs is very little, and is also less by the sampled value erroneous judgement situation that 3 continuous effective diagnostic methods of nothing time-delay cause.So need not open sampled value variable quantity Rule of judgment, to strengthen its identification capability to distortion data.
Beneficial effect of the present invention is following: the invention provides 3 continuous effective diagnostic methods of band time-delay of sampled value and 3 continuous effective diagnostic methods of nothing time-delay of sampled value; Be particularly useful for the real-time processing of electric power system double sampling data; Eliminate the potential hazard of abnormal sample value; Avoid the appearance of situation such as protection measure and control device tripping that the abnormal sample value causes or malfunction, guarantee the safe and stable operation of electric power system.
Description of drawings
Below in conjunction with accompanying drawing the present invention is further described.
Fig. 1 is 3 continuous effective diagnostic method flow charts of band time-delay of sampled value of the present invention.
Fig. 2 is 3 continuous effective diagnostic method flow charts of nothing time-delay of sampled value of the present invention.
Fig. 3 for the present invention to certain segment fault after-current waveform sampling data simulation figure as a result.
Simulation result figure after Fig. 4 the present invention superposeed immediately to 1～3 sampled point at every each 50 o'clock to certain segment fault after-current waveform sampling data.
Fig. 5 is the method judged result sketch map at partial enlarged drawing-single distortion data place of Fig. 4.
Fig. 6 is the partial enlarged drawing of Fig. 4---the method judged result sketch map at continuous 2 distortion data places.
Fig. 7 is the partial enlarged drawing of Fig. 4---the method judged result sketch map at continuous 3 distortion data places.
Fig. 8 is the judged result sketch map of the present invention in sampled data when containing the TA saturated conditions.
Fig. 9 sends out figure big for the part of Fig. 8---the effective diagnostic method judged result of various sampled values when saturated takes place.
Figure 10 is that the present invention is at the outside BC phase fault of certain transformer, the judged result sketch map of three-phase current when B phase TA is saturated.
Figure---each phase current sampling value validity judged result constantly takes place to Figure 11 in short trouble for the part of Figure 10 is sent out big.
Figure 12 is the judged result sketch map of the present invention's three-phase voltage when the outside BC phase fault of certain transformer.
Figure---each phase voltage sampled value validity judged result constantly takes place to Figure 13 in short trouble for the part of Figure 12 is sent out big.
Embodiment
With reference to the accompanying drawings and combine embodiment that the present invention is described in further detail.But the invention is not restricted to given example.
As shown in Figure 1; Flow chart for 3 continuous effective diagnostic methods of the band of sampled value of the present invention time-delay is provided with the data buffer zone that length equals 3, and sampled value moves into, shifts out the data buffer zone successively with FIFO ground form; Relate to following several criterion (threshold) in the whole differentiation process
1, the minimum Seiko threshold of instrument transformer: determine by the instrument transformer self-characteristic;
2, curve can be led down differential errors threshold ε continuously
1: ε
1=m
1A
1(ω T
s)
2, m
1Be first safety factor, its span is [2,7], m
1Generally get 3, A
1Be the maximum fundamental voltage amplitude of system power voltage, be the convenience of calculation of adjusting, A
1Can be simply alternative with the multiple value of electric current voltage rating, get 20 times rated value like current component, component of voltage is got 2 times rated value, and ω is specified angular frequency, and Ts is the time in sampling interval;
3, sampled value maximum threshold: when greater than this sampled value maximum threshold being, the decidable sampled value is invalid, and general sampled value maximum threshold can be got the A of twice
1(the maximum fundamental voltage amplitude of system power voltage), also visible system actual conditions and deciding;
4, sampled value equates the counting threshold continuously: be used for that first sampled value is not the constant non-zero constant of continuous 1/2 cycle in the step C judgment data buffering area, this counting threshold should be the sampling number of 1/2 cycle.
Concrete method of discrimination may further comprise the steps:
A, to moving into 3 continuous sampling value f (x in the data buffer zone
K-2), f (x
K-1), f (x
k) carry out real-time judge, f (x
K-2), f (x
K-1), f (x
k) represent the sampled value of k-2, k-1, k sampled point, x respectively
kRepresent the sampling instant of k sampled point, if said 3 point sampling values all less than the minimum Seiko threshold of instrument transformer, the interim state of then said 3 point sampling values is set to effectively, and goes to step D, otherwise goes to step B;
B, judge whether inequality (1) is set up, if this inequality is set up, the interim state of said 3 point sampling values is set to effectively, and goes to step C;
In the inequality (1), Δ f (x
K-1)=f (x
k)-f (x
K-1),
ε
1For curve can be led down differential errors threshold, ε continuously
1=m
1A
1(ω T
s)
2, m
1Be first safety factor, m
1Span be [2,7], A
1Be the maximum fundamental voltage amplitude of system power voltage, ω is specified angular frequency, and Ts is the time in sampling interval;
C, if the data buffer zone in first sampled value f (x
K-2) interim state be effectively, sampled value f (x
K-2) be less than or equal to sampled value maximum threshold, and it is not the constant non-zero constant of continuous 1/2 cycle, then keeps this sampled value f (x
K-2) interim state and go to step D, otherwise sampled value f (x
K-2) interim state be set to invalid and go to step D;
In this step, for sampled value f (x
K-2) whether be the judgement of the constant non-zero constant of continuous 1/2 cycle, introduced a counter, the sampled point number of 1/2 cycle is sampled value and equates the counting threshold continuously; Be assumed to be 40; When certain sampled value equated with last sampled value, counter added up 1, when the sampled point number that equates continuously reaches 40; Can think that then sampled value keeps continuous 1/2 cycle constant, promptly this sampled value of decidable is invalid.In case a certain sampled value is judged to effectively, or unequal with last point sampling value, and counter is zero clearing at once.
If D sampled value f is (x
K-2) interim state be effectively, then judge this sampled value f (x
K-2) effectively, otherwise this sampled value f (x
K-2) invalid.
Further, first safety factor can be used formula m
1=∑ n
2p
nCalculate, n is a harmonic number, p
nRatio for nth harmonic amplitude and fundamental voltage amplitude.
If current sampling point f (x
K-2) be first or second point data, then directly judge current sampling point f (x
K-2) effectively.
As shown in Figure 2,3 the continuous effective diagnostic methods of nothing time-delay for sampled value of the present invention relate to following several criterion (threshold) in the whole differentiation process:
1, the minimum Seiko threshold of instrument transformer: determine by the instrument transformer self-characteristic;
2, curve can be led down differential errors threshold ε continuously
1: ε
1=m
1A
1(ω T
s)
2, m
1Span be [2,7], m
1Generally get 3, A
1Be the maximum fundamental voltage amplitude of system power voltage, be the convenience of calculation of adjusting, A
1Can be simply alternative with the multiple value of electric current voltage rating, get 20 times rated value like current component, component of voltage is got 2 times rated value, and ω is specified angular frequency, and Ts is the time in sampling interval;
3, sampled value maximum threshold: when greater than this sampled value maximum threshold being, the decidable sampled value is invalid, and general sampled value maximum threshold can be got the A of twice
1(the maximum fundamental voltage amplitude of system power voltage), also visible system actual conditions and deciding;
4, sampled value equates the counting threshold continuously: be used for that first sampled value is not the constant non-zero constant of continuous 1/2 cycle in the step f judgment data buffering area, this counting threshold should be the sampling number of 1/2 cycle
5, curve discontinuous point sampled value becomes threshold more: but the continuous sampled value variable quantity at the true discontinuous point of lead curve place of segmentation, though, can limit threshold less than certain greater than the transition threshold of curve continuity point sampled value.This qualification threshold value can be described as curve discontinuous point sampled value and becomes threshold more.For current-voltage sampling value curve in the system, the big I of its discontinuous point sampled value transition threshold is provided with according to its actual physical implication.Like component of voltage; The point of its sampled value upward transition (absolute value of sampled value changes from small to big), if be pressed onto the process of pressure from nothing corresponding to primary equipment, the switching overvoltage when considering the circuit air-drop; Its variable quantity size is no more than 3 times of rated voltage amplitude; The point of sampled value downward transition (absolute value of sampled value from large to small) does not have the process of pressing corresponding to primary equipment from having to be pressed onto, and variable quantity should be less than the absolute value of maximum sampled value in its last cycle.And current component; Be subjected to the influence of system stored energy element or the restriction of breaker current interruption ability; The change of system network architecture can not make its primary current size from the zero maximum that directly jumps to, or opposite, so can its sampled value transition threshold (like 2 times load current value) be set based on empirical value;
6, the transition threshold ε of curve continuity point sampled value
2: ε
2=m
2A
1ω T
s, m
2Be second safety factor, m
2Span be [2,4], m
2Generally get 3;
Concrete discriminating step comprises:
A, if current sampled value f (x
k) more last point sampling value f (x
K-1) variable quantity become threshold more greater than curve discontinuous point sampled value, then declare current sampled value f (x
k) invalid, otherwise go to step b, f (x
k), f (x
K-1) for representing the sampled value of k, k-1 sampled point, x respectively
k, x
K-1Represent the sampling instant of k, k-1 sampled point respectively;
B, to the slow f (x of up-to-date 3 point sampling data
K-2), f (x
K-1), f (x
k) carry out real-time judge, f (x
K-2) sampled value of expression k-2 sampled point, x
K-2Represent the sampling instant of k-2 sampled point, if said 3 point sampling values are all less than the minimum Seiko threshold of instrument transformer, then with current sampled value f (x
k) interim state be set to effectively, and go to step f, otherwise go to step c;
If c is current sampled value f (x
k) greater than sampled value maximum threshold, then judge current sampled value f (x
k) invalid, otherwise go to steps d;
D, judge whether said 3 point sampling values satisfy inequality (1),, then go to step f, otherwise go to step e if this inequality is set up;
In the inequality (1), Δ f (x
K-1)=f (x
k)-f (x
K-1),
ε
1For curve can be led down differential errors threshold, ε continuously
1=m
1A
1(ω T
s)
2, m
1Be first safety factor, m
1Span be [2,7], A
1Be the maximum fundamental voltage amplitude of system power voltage, ω is specified angular frequency, and Ts is the time in sampling interval;
E, judge whether inequality (2) is set up,, then go to step f, otherwise judge current sampled value f (x if inequality (2) is set up
k) be invalid;
In the inequality (2),
ε
2Be the transition threshold of curve continuity point sampled value, ε
2=m
2A
1ω T
s, m
2Be second safety factor, m
2Span be [2,4];
If f is current sampled value f (x
k) be not the constant non-zero constant of continuous 1/2 cycle, then declare current sampled value f (x
k) effectively, otherwise declare current sampled value f (x
K-2) invalid.
Further, first safety factor can pass through formula m
1=∑ n
2p
nCalculate acquisition, second safety factor can pass through formula m
2=∑ np
nCalculate acquisition, n is a harmonic number in the formula, p
nRatio for nth harmonic amplitude and fundamental voltage amplitude.
If current sampling point f (x
k) be first or second point data, then judge current sampling point f (x
k) effectively.
For reducing the quantity of invalid sampled point, can in its deterministic process, increase the sampled value variable quantity and judge, for being judged to invalid sampled value, if its more last point sampling value variable quantity is less than the transition threshold ε of curve continuity point sampled value
2, then this sampled value is changed the original sentence to effectively.
Simulation process analytic process to Mathematical Modeling is following:
Select for use line end to be provided with 330kV, the 250km high-tension line of serial compensation capacitance and shunt reactor; Current waveform when behind the capacitor three-phase shortcircuit taking place (Zhu Shengshi. high-voltage fence Principles of Relay Protection and technology. the 3rd edition. Beijing: China Electric Power Publishing House; 2005.P79 as simulation object, its equation is described as page or leaf [routine 3-2]):
Modus ponens (A-1) is analyzed at one section waveform in [0s, the 0.3s] time period.Data sampling rate to wavy curve is 4000Hz, T
s=0.00025.Know by formula (A-1),
Get m
1=3, m
2=3.Curve can be led down differential errors threshold value ε continuously
1=m
1A
1(ω T
s)
2≈ 10.09, the transition threshold ε of curve continuity point sampled value
2=m
2A
1ω T
s≈ 128.5.And make that sampled value maximum threshold is 2A
1, minimum Seiko electric current is 1A, sampled value equates that continuously the counting threshold is 80/2=40.
Earlier initial data is carried out emulation.The result shows that 2 kinds of abnormal data discrimination methods all do not have the erroneous judgement situation to normal sampled value, shows that they have excellent adaptability to the system failure waveform that contains decay high order harmonic component and DC component.Analysis result such as accompanying drawing 3 show.
For verifying the identification capability of 2 kinds of abnormal data discrimination methods to abnormal data, every behind 50 o'clock random values that 1～3 sampled point superposeed in original sampling data, emulation once more.The result shows that the effect of 3 continuous effective diagnostic methods of band time-delay is best, can accomplish not judge by accident, do not fail to judge; Do not open 3 continuous effective diagnostic methods of nothing time-delay of sampled value variable quantity Rule of judgment, can 2 normal sampled point erroneous judgements behind the abnormal data are invalid, but can not fail to judge; 3 continuous effective diagnostic methods of nothing time-delay behind the open sampled value variable quantity Rule of judgment are general only invalid with 1 normal sampled point erroneous judgement behind the abnormal data, but the situation of failing to judge can occur.Analysis result such as accompanying drawing 4～Fig. 8 show.
Following to a transformer BC phase-to phase fault recorder data simulation analysis process respectively:
The test data sample rate is 1000Hz.The magnitude of current there is A
1=2000, voltage there is A
1=2600.Fixedly get m in the simulation process
1=3, m
2=3, and make that sampled value maximum threshold is 2A
1, minimum Seiko electric current is 1A, sampled value equates that continuously the counting threshold is 20/2=10.
3 phase current simulation results such as accompanying drawing 9, accompanying drawing 10 are shown.Simulation result shows, 3 continuous effective diagnostic methods of band time-delay can well adapted TA saturated conditions, can the discontinuous point erroneous judgement be invalid data; Through open sampled value variable quantity Rule of judgment, there is not the erroneous judgement situation that 3 continuous effective diagnostic methods of time-delay can significantly reduce the discontinuous point data.
3 phase voltage simulation results such as accompanying drawing 11, accompanying drawing 12 are shown.Emulation to fault phase (B, C) component of voltage shows that in the moment that fault takes place and excises, obvious discontinuous point has appearred in voltage waveform.3 discriminating powers that the continuous effective diagnostic method is done well at the discontinuous point place of band time-delay, it is invalid can not judge discontinuous point place sampled value by accident; Not having 3 continuous effective diagnostic methods of time-delay can be invalid with discontinuous point place adopted value and neighbouring sample value erroneous judgement thereafter, but behind the open sampled value variable quantity Rule of judgment, the erroneous judgement situation disappears.
It is thus clear that; Continuous sampling value method for distinguishing validity of the present invention can be guaranteed the correct reliability of sampled data, eliminates the potential hazard of abnormal sample value; Avoid the appearance of situation such as protection measure and control device tripping that the abnormal sample value causes or malfunction, the operation of protection power system safety and stability.
Except that the foregoing description, the present invention can also have other execution modes.All employings are equal to the technical scheme of replacement or equivalent transformation formation, all drop on the protection range of requirement of the present invention.
Claims (5)
1. 3 continuous effective diagnostic methods of the band of sampled value time-delay, it is characterized in that: be provided with the data buffer zone that length equals 3, sampled value moves into, shifts out the data buffer zone successively with the form of FIFO, and concrete method of discrimination may further comprise the steps:
A, to moving into 3 continuous sampling value f (x in the data buffer zone
K-2), f (x
K-1), f (x
k) carry out real-time judge, f (x
K-2), f (x
K-1), f (x
k) represent the sampled value of k-2, k-1, k sampled point, x respectively
kRepresent the sampling instant of k sampled point, if said 3 point sampling values all less than the minimum Seiko threshold of instrument transformer, the interim state of then said 3 point sampling values is set to effectively, and goes to step D, otherwise goes to step B;
B, judge whether inequality (1) is set up, if this inequality is set up, the interim state of said 3 point sampling values is set to effectively, and goes to step C;
In the inequality (1), Δ f (x
K-1)=f (x
k)-f (x
K-1),
ε
1For curve can be led down differential errors threshold, ε continuously
1=m
1A
1(ω T
s)
2, m
1Be first safety factor, m
1Span be [2,7], A
1Be the maximum fundamental voltage amplitude of system power voltage, ω is specified angular frequency, T
sBe the time in sampling interval;
C, if the data buffer zone in first sampled value f (x
K-2) interim state be effectively, sampled value f (x
K-2) be less than or equal to sampled value maximum threshold, and it is not the constant non-zero constant of continuous 1/2 cycle, then keeps this sampled value f (x
K-2) interim state and go to step D, otherwise sampled value f (x
K-2) interim state be set to invalid and go to step D;
If D sampled value f is (x
K-2) interim state be effectively, then judge this sampled value f (x
K-2) effectively, otherwise this sampled value f (x
K-2) invalid.
2. 3 continuous effective diagnostic methods of the band of sampled value according to claim 1 time-delay is characterized in that: the said first safety factor m
1=∑ n
2p
n, n is a harmonic number, p
nRatio for nth harmonic amplitude and fundamental voltage amplitude.
3. 3 continuous effective diagnostic methods of the nothing of sampled value time-delay is characterized in that step comprises:
A, if current sampled value f (x
k) more last point sampling value f (x
K-1) variable quantity greater than curve discontinuous point sampled value transition threshold, then declare current sampled value f (x
k) invalid, otherwise go to step b, f (x
k), f (x
K-1) for representing the sampled value of k, k-1 sampled point, x respectively
k, x
K-1Represent the sampling instant of k, k-1 sampled point respectively;
B, to up-to-date 3 point sampling data f (x
K-2), f (x
K-1), f (x
k) carry out real-time judge, f (x
K-2) sampled value of expression k-2 sampled point, x
K-2Represent the sampling instant of k-2 sampled point, if said 3 point sampling values are all less than the minimum Seiko threshold of instrument transformer, then with current sampled value f (x
k) interim state be set to effectively, and go to step f, otherwise go to step c;
If c is current sampled value f (x
k) greater than sampled value maximum threshold, then judge current sampled value f (x
k) invalid, otherwise go to steps d;
D, judge whether said 3 point sampling values satisfy inequality (1),, then go to step f, otherwise go to step e if this inequality is set up;
In the inequality (1), Δ f (x
K-1)=f (x
k)-f (x
K-1),
ε
1For curve can be led down differential errors threshold, ε continuously
1=m
1A
1(ω T
s)
2, m
1Be first safety factor, m
1Span be [2,7], A
1Be the maximum fundamental voltage amplitude of system power voltage, ω is specified angular frequency, T
sBe the time in sampling interval;
E, judge whether inequality (2) is set up,, then go to step f, otherwise judge current sampled value f (x if inequality (2) is set up
k) be invalid;
In the inequality (2),
ε
2Be the transition threshold of curve continuity point sampled value, ε
2=m
2A
1ω T
s, m
2Be second safety factor, m
2Span be [2,4];
If f is current sampled value f (x
k) be not the constant non-zero constant of continuous 1/2 cycle, then declare current sampled value f (x
k) effectively, otherwise declare current sampled value f (x
k) invalid.
4. 3 continuous effective diagnostic methods of the nothing of sampled value according to claim 3 time-delay is characterized in that: the said first safety factor m
1=∑ n
2p
n, the second safety factor m
2=∑ np
n, n is a harmonic number in the formula, p
nRatio for nth harmonic amplitude and fundamental voltage amplitude.
5. 3 continuous effective diagnostic methods of the nothing of sampled value according to claim 3 time-delay is characterized in that: for being judged to invalid sampled value, if its more last point sampling value variable quantity is less than the transition threshold ε of curve continuity point sampled value
2, then this sampled value is changed the original sentence to effectively.
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