CN102508107A - Detection method of zero sequence current mutual inductor of small current system - Google Patents

Detection method of zero sequence current mutual inductor of small current system Download PDF

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CN102508107A
CN102508107A CN2011103940886A CN201110394088A CN102508107A CN 102508107 A CN102508107 A CN 102508107A CN 2011103940886 A CN2011103940886 A CN 2011103940886A CN 201110394088 A CN201110394088 A CN 201110394088A CN 102508107 A CN102508107 A CN 102508107A
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mutual inductor
current mutual
zero sequence
weight coefficient
sequence current
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CN102508107B (en
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尹刚
罗建
尹松
李长明
唐晨旭
尹冬
沈重衡
李卓蔓
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Chongqing University
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Chongqing University
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Abstract

The invention discloses a detection method of a zero sequence current mutual inductor of a small current system, relates to a detection method of a current mutual inductor and in particular relates to a detection method of a zero sequence current mutual inductor of a small current system. According to the invention, a high-frequency current signal is injected into a secondary side for protecting the current mutual inductor, and a self-adaptive sine digital filter is used for extracting signals, so that the following major difficulties are solved: when the system is normally operated, the primary side of the system has a high voltage, so that the zero sequence current mutual inductor cannot get an exciting current directly through the primary side and the injected signal is submerged due to unbalance of a power frequency current; and the detection method can be used for detecting the zero sequence current mutual inductor under an uninterrupted power condition.

Description

The zero sequence current mutual inductor detection method of small current system
Technical field
The present invention relates to a kind of detection methods of current transformer, more particularly to a kind of zero sequence current mutual inductor detection method of small current system.
Background technique
In power distribution network, zero sequence current mutual inductor is the important devices for reflecting ground fault, sense of current is changing at any time in ac circuit, the polarity of current transformer refers to that a certain moment primary side current is positive simultaneously with secondary side one end current direction or is negative simultaneously, also referred to as this polarity is Same Name of Ends or homopolar end, the primary side of zero sequence current mutual inductor is exactly the sum of cable three-phase current, the correctness of zero sequence current mutual inductor then refers to the correct corresponding relationship of zero sequence current mutual inductor Yu place cable, it determines the correct corresponding relationship of zero sequence current mutual inductor and line-selected earthing device or protective device.
The polarity and correctness of zero sequence current mutual inductor directly determine that can line-selected earthing device correctly act and correct route selection, so before installing line-selected earthing device and protective device additional must polarity to zero sequence current mutual inductor and correctness detect, current polarity of zero-sequence current transformer and accuracy detection method is in the case where system blackout, the polarity and correctness of zero sequence current mutual inductor are verified, the raising required with power supply reliability, have a power failure the reduction again and again planned, the polarity of detection zero sequence current mutual inductor that has a power failure and correctness not only will cause loss of outage, and it is difficult to carry out.When system operates normally, due to the primary side band high voltage of system, so directly can not make the imbalance of exciting current and power current on zero sequence current mutual inductor band that will flood Injection Signal by primary side.
Therefore those skilled in the art are dedicated to developing a kind of method for detecting the polarity and correctness of zero sequence current mutual inductor when system operates normally.
Summary of the invention
In view of the above drawbacks of the prior art, technical problem to be solved by the invention is to provide a kind of methods detected when system is operated normally to the polarity and correctness of zero sequence current mutual inductor.
To achieve the above object, the present invention provides a kind of zero sequence current mutual inductor detection methods of small current system, it is characterised in that: the Check up polarity of accuracy detection and zero sequence current mutual inductor including zero sequence current mutual inductor；The accuracy of the zero sequence current mutual inductor detect the following steps are included:
Apply high-frequency current signal on the secondary side of protective current mutual inductor；
Using adaptive sine digital filter obtain input current pumping signal and zero sequence current mutual inductor response signal synchronization amplitude；
The amplitude of the response signal on each group cable zero sequence current mutual inductor pair side is compared; when wherein one group zero sequence current mutual inductor pair while high frequency signal current be the zero sequence current mutual inductor pair of other each groups while the sum of high frequency signal current; then the zero sequence current mutual inductor is just and protective current mutual inductor is in same group of cable; conversely, the zero sequence current mutual inductor just and protective current mutual inductor not in same group of cable；
The Check up polarity of the zero sequence current mutual inductor the following steps are included:
Apply high-frequency current signal on the secondary side of protective current mutual inductor；
Using adaptive sine digital filter obtain input current pumping signal and zero sequence current mutual inductor response signal synchronization phase；
If protective current mutual inductor it is secondary while as input terminal, zero sequence current mutual inductor it is secondary while be used as output end；If the secondary system when arriving zero sequence current mutual inductor pair by current direction of protective current mutual inductor is intermediate system, the transmission function phase of the intermediate system is；If the phase of the pumping signal is
Figure 67801DEST_PATH_IMAGE002
；The phase of the response signal is
Figure 2011103940886100002DEST_PATH_IMAGE003
；In synchronization, when
Figure 416742DEST_PATH_IMAGE004
When, the protective current mutual inductor and the zero sequence current mutual inductor are same polarity；In synchronization, when
Figure 2011103940886100002DEST_PATH_IMAGE005
When, protective current mutual inductor and zero sequence current mutual inductor are reversed polarity.
Preferably, it is described using adaptive sine digital filter obtain input current pumping signal and zero sequence current mutual inductor response signal phase the following steps are included:
The input of S1, the adaptive sine digital filter are SIN function
Figure 868452DEST_PATH_IMAGE006
, described
Figure 2011103940886100002DEST_PATH_IMAGE007
For fundamental wave frequency,
Figure 215120DEST_PATH_IMAGE008
For positive integer,For the function of time；
S2, by the SIN function
Figure 514700DEST_PATH_IMAGE006
With weight coefficient
Figure 2011103940886100002DEST_PATH_IMAGE011
It is multiplied, the weight coefficientIt is actual valueEstimated value；
S3, by the SIN functionThrough
Figure 2011103940886100002DEST_PATH_IMAGE013
Phase shift become after cosine function again with weight coefficient
Figure 326392DEST_PATH_IMAGE014
It is multiplied, the weight coefficient
Figure 300164DEST_PATH_IMAGE014
It is actual value
Figure 2011103940886100002DEST_PATH_IMAGE015
Estimated value；
S4, step S2 is added to obtain the output of the adaptive sine digital filter with the obtained two paths of signals of step S3
Figure 237902DEST_PATH_IMAGE016
；
S5, adaptive sine digital filter output
Figure 297125DEST_PATH_IMAGE016
Inverted rear and real input signal
Figure 2011103940886100002DEST_PATH_IMAGE017
=It is added, obtains the error of adaptive sine digital filter
Figure 2011103940886100002DEST_PATH_IMAGE019
, described
Figure 72369DEST_PATH_IMAGE020
For positive integer；
S6, foundation error
Figure 56374DEST_PATH_IMAGE019
The mean square error of the adaptive sine digital filter can be obtained
Figure 2011103940886100002DEST_PATH_IMAGE021
；Pass through
Figure 727527DEST_PATH_IMAGE022
=
Figure 2011103940886100002DEST_PATH_IMAGE023
Figure 2011103940886100002DEST_PATH_IMAGE025
With
Figure 20023DEST_PATH_IMAGE026
=
Figure 2011103940886100002DEST_PATH_IMAGE027
Figure 112612DEST_PATH_IMAGE024
Figure 395695DEST_PATH_IMAGE028
Adjust weight coefficient
Figure 44982DEST_PATH_IMAGE011
With
Figure 300383DEST_PATH_IMAGE014
, make the mean square error of the adaptive sine digital filter
Figure 626191DEST_PATH_IMAGE021
Reach minimum；It is described
Figure 881723DEST_PATH_IMAGE022
For weight coefficientWeight coefficient adjusted, it is described
Figure 506925DEST_PATH_IMAGE026
For weight coefficient
Figure 941318DEST_PATH_IMAGE014
Weight coefficient adjusted,
Figure 933413DEST_PATH_IMAGE024
>0,
Figure 924503DEST_PATH_IMAGE024
For adaptation coefficient, it to be used for control stability and convergence rate；
S7, acquirement are worked as
Figure 888917DEST_PATH_IMAGE021
Weight coefficient when minimum
Figure 556527DEST_PATH_IMAGE011
With, obtain
Figure 2011103940886100002DEST_PATH_IMAGE029
； 
Figure 893017DEST_PATH_IMAGE030
For the phase of signal.
Preferably, it is described using adaptive sine digital filter obtain input current pumping signal and zero sequence current mutual inductor response signal amplitude the following steps are included:
The input of S1, the adaptive sine digital filter are SIN function
Figure 39833DEST_PATH_IMAGE006
, described
Figure 816028DEST_PATH_IMAGE007
For fundamental wave frequency,For positive integer,
Figure 115608DEST_PATH_IMAGE010
For the function of time；
S2, by the SIN function
Figure 867664DEST_PATH_IMAGE006
With weight coefficient
Figure 877077DEST_PATH_IMAGE011
It is multiplied, the weight coefficient
Figure 81793DEST_PATH_IMAGE011
It is actual value
Figure 405327DEST_PATH_IMAGE012
Estimated value；
S3, by the SIN function
Figure 261157DEST_PATH_IMAGE006
ThroughPhase shift become after cosine function again with weight coefficient
Figure 219238DEST_PATH_IMAGE014
It is multiplied, the weight coefficient
Figure 408780DEST_PATH_IMAGE014
It is actual valueEstimated value；
S4, step S2 is added to obtain the output of the adaptive sine digital filter with the obtained two paths of signals of step S3
Figure 345698DEST_PATH_IMAGE016
；
S5, adaptive sine digital filter outputInverted rear and real input signal
Figure 190343DEST_PATH_IMAGE017
=It is added, obtains the error of adaptive sine digital filter
Figure 480565DEST_PATH_IMAGE019
, describedFor positive integer；
S6, foundation error
Figure 412935DEST_PATH_IMAGE019
The mean square error of the adaptive sine digital filter can be obtained
Figure 583016DEST_PATH_IMAGE021
；Pass through
Figure 479297DEST_PATH_IMAGE022
=
Figure 616886DEST_PATH_IMAGE023
Figure 437074DEST_PATH_IMAGE024
Figure 976509DEST_PATH_IMAGE025
With
Figure 856740DEST_PATH_IMAGE026
=
Figure 437129DEST_PATH_IMAGE028
Adjust weight coefficient
Figure 737529DEST_PATH_IMAGE011
With
Figure 787394DEST_PATH_IMAGE014
, make the mean square error of the adaptive sine digital filter
Figure 949385DEST_PATH_IMAGE021
Reach minimum；It is described
Figure 463412DEST_PATH_IMAGE022
For weight coefficient
Figure 419866DEST_PATH_IMAGE011
Weight coefficient adjusted, it is described
Figure 19344DEST_PATH_IMAGE026
For weight coefficientWeight coefficient adjusted,
Figure 353559DEST_PATH_IMAGE024
>0,
Figure 746494DEST_PATH_IMAGE024
For adaptation coefficient, it to be used for control stability and convergence rate；
S7, acquirement are worked as
Figure 567689DEST_PATH_IMAGE021
Weight coefficient when minimumWith
Figure 560101DEST_PATH_IMAGE014
, obtain
Figure 2011103940886100002DEST_PATH_IMAGE031
；For the amplitude of signal.
Preferably, the step of making the reactance of cable and direct-to-ground capacitance reach resonant state the invention also includes the frequency of adjustment high-frequency current signal.
The beneficial effects of the present invention are: the present invention applies high-frequency current signal on the secondary side of protective current mutual inductor; signal is extracted using adaptive sine digital filter; overcome the primary side band high voltage when system is operated normally due to system; it directly can not make the imbalance of exciting current and power current on zero sequence current mutual inductor band that will flood the great difficult problem of Injection Signal by primary side, zero sequence current mutual inductor can be detected in case of constant power.
Detailed description of the invention
Fig. 1 is the flow chart of the zero sequence current mutual inductor detection method of small current system.
Fig. 2 is the equivalent circuit diagram of high frequency signal current access.
Fig. 3 is the structure principle chart of adaptive sine digital filter.
Specific embodiment
Present invention will be further explained below with reference to the attached drawings and examples:
As shown in Figure 1 to Figure 3, the zero sequence current mutual inductor detection method of a kind of small current system, including zero sequence current mutual inductor accuracy detection and zero sequence current mutual inductor Check up polarity, the zero sequence current mutual inductor accuracy detection the following steps are included:
Apply high-frequency current signal to protective current mutual inductor pair side, this high-frequency current signal will induce faint high-frequency current on cable, the impedance value of transformer and load is very big, to this high-frequency signal at high resistant resistance, by cable, bus and direct-to-ground capacitance are that high frequency signal current access is regarded in path as, adjust the frequency of this high-frequency current signal, when the reactance of cable and direct-to-ground capacitance reach resonant state, the impedance value of high-frequency signal access at this time is up to minimum, inducing current signal will be most strong, using adaptive sine digital filter obtain input current pumping signal and zero sequence current mutual inductor response signal synchronization amplitude, the amplitude of the response signal on each group cable zero sequence current mutual inductor pair side is compared, the equivalent circuit L1 of high-frequency signal network path, L2, L3, L4 ... inductance and capacitor in Ln are respectively the equivalent impedance and direct-to-ground capacitance that high-frequency signal network path corresponds to cable, and L2, L3, L4 ..., Ln are connected in series with L1 again after being in parallel, and the amplitude of high frequency signal current is respectively
Figure 2011103940886100002DEST_PATH_IMAGE033
、
Figure 557062DEST_PATH_IMAGE034
、
Figure 2011103940886100002DEST_PATH_IMAGE035
、
Figure 989180DEST_PATH_IMAGE036
…、
Figure 2011103940886100002DEST_PATH_IMAGE037
, then just being had according to Kirchhoff's current law (KCL)
Figure 269989DEST_PATH_IMAGE038
…+Detect the high frequency signal current on each group cable zero sequence current mutual inductor pair side; when wherein one group zero sequence current mutual inductor pair while high frequency signal current be the zero sequence current mutual inductor pair of other each groups while the sum of high frequency signal current; then the zero sequence current mutual inductor is just and protective current mutual inductor is in same group of cable; conversely, the zero sequence current mutual inductor just and protective current mutual inductor not in same group of cable.
If L1, L2, L3 ..., the parameter of tri- groups of cables of Ln it is equal, due to the symmetry of each group cable, it is possible to obtain
Figure 2011103940886100002DEST_PATH_IMAGE039
It can thus be appreciated that; when wherein one group of cable zero sequence current mutual inductor pair while high frequency signal current amplitude be other each group cable zero sequence current mutual inductor pairs while n-1 times of high frequency signal current amplitude when, the zero sequence current mutual inductor and protective current mutual inductor of the group are located at same group of cable.
In a practical situation; wherein one group of zero sequence current mutual inductor pair while high frequency signal current be the zero sequence current mutual inductor pair of other each groups while the sum of high frequency signal current, i.e., the maximum zero sequence current mutual inductor of secondary side high frequency signal current and protective current mutual inductor are in same group of cable.
The Check up polarity of the zero sequence current mutual inductor is the following steps are included: this high-frequency current signal will induce faint high-frequency current on cable, the impedance value of transformer and load is very big, to this high-frequency signal at high resistant resistance, by cable, bus and direct-to-ground capacitance are that access is regarded in path as, adjust the frequency of this high-frequency current signal, when the reactance of cable and direct-to-ground capacitance reach resonant state, the impedance value of high-frequency signal access at this time is up to minimum, inducing current signal will be most strong, using adaptive sine digital filter obtain input current pumping signal and zero sequence current mutual inductor response signal synchronization phase, if the secondary side of protective current mutual inductor is as input terminal, the secondary side of zero sequence current mutual inductor is as output end, if the secondary side of protective current mutual inductor is by current direction to zero sequence current mutual inductance The system on device pair side is intermediate system, and the transmission function phase of the intermediate system is
Figure 925147DEST_PATH_IMAGE001
If the phase of the pumping signal is
Figure 20011DEST_PATH_IMAGE002
, the phase of the response signal is
Figure 968375DEST_PATH_IMAGE003
, in synchronization, when
Figure 123282DEST_PATH_IMAGE004
When, the protective current mutual inductor and the zero sequence current mutual inductor are same polarity, in synchronization, when
Figure 157097DEST_PATH_IMAGE005
When, protective current mutual inductor and zero sequence current mutual inductor are reversed polarity.
It is described using adaptive sine digital filter obtain input current pumping signal and zero sequence current mutual inductor response signal phase the following steps are included:
The input of S1, the adaptive sine digital filter are SIN function
Figure 55652DEST_PATH_IMAGE006
, described
Figure 858523DEST_PATH_IMAGE007
For fundamental wave frequency,
Figure 184331DEST_PATH_IMAGE008
For positive integer,
Figure 705442DEST_PATH_IMAGE010
For the function of time；
S2, by the SIN functionWith weight coefficient
Figure 252016DEST_PATH_IMAGE011
It is multiplied, the weight coefficientIt is actual valueEstimated value；
S3, by the SIN function
Figure 771660DEST_PATH_IMAGE006
Through
Figure 798390DEST_PATH_IMAGE013
Phase shift become after cosine function again with weight coefficientIt is multiplied, the weight coefficient
Figure 961704DEST_PATH_IMAGE014
It is actual value
Figure 490906DEST_PATH_IMAGE015
Estimated value；
S4, step S2 is added to obtain the output of the adaptive sine digital filter with the obtained two paths of signals of step S3
Figure 372143DEST_PATH_IMAGE016
；
S5, adaptive sine digital filter output
Figure 226967DEST_PATH_IMAGE016
Inverted rear and real input signal
Figure 193654DEST_PATH_IMAGE017
=
Figure 713497DEST_PATH_IMAGE018
It is added, obtains the error of adaptive sine digital filter
Figure 465553DEST_PATH_IMAGE019
, described
Figure 474966DEST_PATH_IMAGE020
For positive integer；
S6, foundation error
Figure 679682DEST_PATH_IMAGE019
The mean square error of the adaptive sine digital filter can be obtained；Pass through
Figure 672095DEST_PATH_IMAGE022
=
Figure 852409DEST_PATH_IMAGE023
Figure 544422DEST_PATH_IMAGE024
Figure 468385DEST_PATH_IMAGE025
With
Figure 116404DEST_PATH_IMAGE026
=
Figure 483931DEST_PATH_IMAGE027
Figure 912507DEST_PATH_IMAGE024
Adjust weight coefficient
Figure 893418DEST_PATH_IMAGE011
With
Figure 415536DEST_PATH_IMAGE014
, make the mean square error of the adaptive sine digital filter
Figure 269091DEST_PATH_IMAGE021
Reach minimum；It is described
Figure 285589DEST_PATH_IMAGE022
For weight coefficient
Figure 908200DEST_PATH_IMAGE011
Weight coefficient adjusted, it is described
Figure 866797DEST_PATH_IMAGE026
For weight coefficient
Figure 755119DEST_PATH_IMAGE014
Weight coefficient adjusted；
S7, acquirement are worked as
Figure 824575DEST_PATH_IMAGE021
Weight coefficient when minimum
Figure 114742DEST_PATH_IMAGE011
With, obtain
Figure 806809DEST_PATH_IMAGE029
； 
Figure 165109DEST_PATH_IMAGE030
For the phase of signal.
It is described using adaptive sine digital filter obtain input current pumping signal and zero sequence current mutual inductor response signal amplitude the following steps are included:
The input of S1, the adaptive sine digital filter are SIN function
Figure 824630DEST_PATH_IMAGE006
, described
Figure 875762DEST_PATH_IMAGE007
For fundamental wave frequency,
Figure 987944DEST_PATH_IMAGE008
For positive integer,
Figure 149935DEST_PATH_IMAGE010
For the function of time；
S2, by the SIN function
Figure 398382DEST_PATH_IMAGE006
With weight coefficient
Figure 620416DEST_PATH_IMAGE011
It is multiplied, the weight coefficient
Figure 219894DEST_PATH_IMAGE011
It is actual value
Figure 372526DEST_PATH_IMAGE012
Estimated value；
S3, the SIN function is passed through
Figure 491792DEST_PATH_IMAGE013
Phase shift become after cosine function again with weight coefficient
Figure 868416DEST_PATH_IMAGE014
It is multiplied, the weight coefficientIt is actual value
Figure 458983DEST_PATH_IMAGE015
Estimated value；
S4, step S2 is added to obtain the output of the adaptive sine digital filter with the obtained two paths of signals of step S3
Figure 698334DEST_PATH_IMAGE016
；
S5, adaptive sine digital filter output
Figure 245859DEST_PATH_IMAGE016
Inverted rear and real input signal
Figure 570661DEST_PATH_IMAGE017
=
Figure 127414DEST_PATH_IMAGE018
It is added, obtains the error of adaptive sine digital filter
Figure 955692DEST_PATH_IMAGE019
, describedFor positive integer；
S6, foundation error
Figure 486217DEST_PATH_IMAGE019
The mean square error of the adaptive sine digital filter can be obtained
Figure 846660DEST_PATH_IMAGE021
；Pass through
Figure 981975DEST_PATH_IMAGE022
=
Figure 194134DEST_PATH_IMAGE024
Figure 843421DEST_PATH_IMAGE025
With
Figure 895560DEST_PATH_IMAGE026
=
Figure 972100DEST_PATH_IMAGE027
Figure 742479DEST_PATH_IMAGE024
Figure 116828DEST_PATH_IMAGE028
Adjust weight coefficient
Figure 226736DEST_PATH_IMAGE011
With
Figure 474177DEST_PATH_IMAGE014
, make the mean square error of the adaptive sine digital filter
Figure 731852DEST_PATH_IMAGE021
Reach minimum；It is described
Figure 722942DEST_PATH_IMAGE022
For weight coefficientWeight coefficient adjusted, it is described
Figure 354967DEST_PATH_IMAGE026
For weight coefficient
Figure 585091DEST_PATH_IMAGE014
Weight coefficient adjusted；
S7, acquirement are worked as
Figure 629139DEST_PATH_IMAGE021
Weight coefficient when minimum
Figure 261109DEST_PATH_IMAGE011
With
Figure 37304DEST_PATH_IMAGE014
, obtain
Figure 269571DEST_PATH_IMAGE031
；
Figure 602463DEST_PATH_IMAGE032
For the amplitude of signal.
Input signal
Figure 462840DEST_PATH_IMAGE017
It is each harmonic amplitude and phase all indeclinable sinusoidal cycles input signal at any time,
Figure 488565DEST_PATH_IMAGE040
, after the unlimited iteration of adaptive sine wave self-adaption algorithm filter at any time,
Figure 2011103940886100002DEST_PATH_IMAGE041
、The coefficient of the corresponding harmonic components of sinusoidal input signal will be converged on、
Figure 203766DEST_PATH_IMAGE044
, in order to keep proof procedure concise, if the only sinusoidal component containing fundamental wave and triple-frequency harmonics in actual signal
Figure 2011103940886100002DEST_PATH_IMAGE045
,
, wherein
Figure 2011103940886100002DEST_PATH_IMAGE047
For fundamental wave frequency,
Figure 239910DEST_PATH_IMAGE048
,
Figure 2011103940886100002DEST_PATH_IMAGE049
It is actual value respectively
Figure 305824DEST_PATH_IMAGE050
,
Figure 2011103940886100002DEST_PATH_IMAGE051
Weight coefficient, error
Figure 167470DEST_PATH_IMAGE052
=
Figure 815489DEST_PATH_IMAGE017
Figure 2011103940886100002DEST_PATH_IMAGE053
=
Figure 494601DEST_PATH_IMAGE054
+,
Figure 532964DEST_PATH_IMAGE056
=
Figure 2011103940886100002DEST_PATH_IMAGE057
+
Figure 509885DEST_PATH_IMAGE058
+
Figure 2011103940886100002DEST_PATH_IMAGE059
, the mean square error in a period of time is
Figure 215673DEST_PATH_IMAGE060
=
Figure 2011103940886100002DEST_PATH_IMAGE061
+
Figure 862424DEST_PATH_IMAGE062
+
Figure 2011103940886100002DEST_PATH_IMAGE063
,
And if only if weight coefficient
Figure 653662DEST_PATH_IMAGE049
Equal to actual value
Figure 880548DEST_PATH_IMAGE051
When, mean square error is minimum.
The recurrence formula of sinusoidal approximate algorithm is
Figure 690110DEST_PATH_IMAGE064
=
Figure 258494DEST_PATH_IMAGE024
Figure 599346DEST_PATH_IMAGE066
,
Figure 2011103940886100002DEST_PATH_IMAGE067
=
Figure 793436DEST_PATH_IMAGE068
Figure 83603DEST_PATH_IMAGE024
Figure 2011103940886100002DEST_PATH_IMAGE069
,
In formula
Figure 337735DEST_PATH_IMAGE024
>0,
Figure 713353DEST_PATH_IMAGE024
The parameter of a control stability and convergence rate, referred to as adaptation coefficient, regardless of initial weight coefficient be it is how many, true value can be obtained after iteration after a period of time
Figure 258604DEST_PATH_IMAGE051
。
According to
Figure 918124DEST_PATH_IMAGE070
With
Figure 2011103940886100002DEST_PATH_IMAGE071
The amplitude and phase of available signal,
Figure 15262DEST_PATH_IMAGE032
For the amplitude of signal,
Figure 878176DEST_PATH_IMAGE030
For the phase of signal.
Due to
Figure 289434DEST_PATH_IMAGE072
It is an ensemble average parameter, cannot calculates in real time, can be used in programming
Figure 2011103940886100002DEST_PATH_IMAGE073
Instead of
Figure 678827DEST_PATH_IMAGE074
。
In order to further seek polarity and accuracy detection method, verify polarity and correctness detection criteria proposed in this paper, system emulation wiring diagram is established using the power system block-set in MATLAB software herein, emulation proof is carried out for the various modes of distribution network systems.
Power supply be power infinity power supply, transformer capacity 31500MVA, no-load voltage ratio be 110/10.5KV, connection be Y/
Figure 150129DEST_PATH_IMAGE076
, 10kV bus have 4 cables, number be followed successively by Ll, L2, L3, L4; the inductance of cable run is 0.9337mH, and direct-to-ground capacitance 0.0043uF, the power of protective current transformer, is 10VA; no-load voltage ratio is 200/5, and the power of zero sequence current mutual inductor is 10VA, and no-load voltage ratio is 200/5.
0 is set by the power supply of system, in this analogue system, analysis of experiments has been carried out to Injection Signal herein.
The exciting current signal applied on protective current mutual inductor pair side is made to obtain strongest response on zero sequence current mutual inductor, the frequency of the signal should make cable, the access that bus and direct-to-ground capacitance are constituted reaches the frequency of resonance, in order not to cause protective device that malfunction occurs, apply the exciting current that amplitude is 0.03A to protective current mutual inductor, change the frequency of pumping signal, and observe the situation of change of response signal on zero sequence current mutual inductor, finally measuring and responding strongest frequency on zero sequence current mutual inductor is about 350HZ, with the best injected frequency of 350HZ analogue system thus.
Entering amplitude from protective current mutual inductor pair marginal not is 0.03A, and frequency is 350HZ exciting current signal, and the data measured are as shown in the table:
Excitation signal amplitude Pumping signal phase Response signal amplitude Multiplied by (n-1)
0.03 10 0.009194979 0.0275849391
0.03 20 0.009194979 0.0275849391
0.03 30 0.009194979 0.0275849391
0.03 40 0.009194979 0.0275849391
0.03 50 0.009194979 0.0275849391
Table 1
Injection Signal amplitude Pumping signal phase Response signal amplitude Response signal phase Phase difference
0.03 10 0.0275849393 -11.98138 21.98138
0.03 20 0.0275849393 -1.981382 21.98138
0.03 30 0.0275849393 8.018617 21.98138
0.03 40 0.0275849393 18.018617 21.98138
0.03 50 0.0275849393 28.0186176 21.98138
Table 2
Injection Signal amplitude Pumping signal phase Response signal amplitude Response signal phase Phase difference In addition 180 °
0.03 10 0.027584 168.01861 -158.0186 21.981
0.03 20 0.027584 178.01861 -158.0186 21.981
0.03 30 0.027584 188.01861 -158.0186 21.981
0.03 40 0.027584 198.01861 -158.0186 21.981
0.03 50 0.027584 208.01861 -158.0186 21.981
Table 3
Table 1 is the data that protective current mutual inductor and zero sequence current mutual inductor are not measured in same cable, table 2 is the data that protective current mutual inductor and zero sequence current mutual inductor are measured in same cable and same polarity, table 3 is the data that protective current mutual inductor and zero sequence current mutual inductor are measured in same cable and reversed polarity, when the protective current mutual inductor of added excitation and zero sequence current mutual inductor are in same cable line, the amplitude of response signal is not at n-1 times of the response signal amplitude of the zero sequence current mutual inductor of same cable line, when protective current mutual inductor and zero sequence current mutual inductor are same polarity, there is phase relation
Figure 2011103940886100002DEST_PATH_IMAGE077
, there is phase relation in when reversed polarity
Figure 687290DEST_PATH_IMAGE078
, above data demonstrate polarity and correction judgement set forth above according to.
The preferred embodiment of the present invention has been described in detail above.It should be appreciated that those skilled in the art according to the present invention can conceive without creative work makes many modifications and variations.Therefore, all technician in the art, all should be within the scope of protection determined by the claims under this invention's idea on the basis of existing technology by the available technical solution of logical analysis, reasoning, or a limited experiment.

Claims (4)

1. a kind of zero sequence current mutual inductor detection method of small current system, it is characterised in that: the Check up polarity of accuracy detection and zero sequence current mutual inductor including zero sequence current mutual inductor；The accuracy of the zero sequence current mutual inductor detect the following steps are included:
Apply high-frequency current signal on the secondary side of protective current mutual inductor；
Using adaptive sine digital filter obtain input current pumping signal and zero sequence current mutual inductor response signal synchronization amplitude；
The amplitude of the response signal on each group cable zero sequence current mutual inductor pair side is compared; when wherein one group zero sequence current mutual inductor pair while high frequency signal current be the zero sequence current mutual inductor pair of other each groups while the sum of high frequency signal current; then the zero sequence current mutual inductor is just and protective current mutual inductor is in same group of cable; conversely, the zero sequence current mutual inductor just and protective current mutual inductor not in same group of cable；
The Check up polarity of the zero sequence current mutual inductor the following steps are included:
Apply high-frequency current signal on the secondary side of protective current mutual inductor；
Using adaptive sine digital filter obtain input current pumping signal and zero sequence current mutual inductor response signal synchronization phase；
If protective current mutual inductor it is secondary while as input terminal, zero sequence current mutual inductor it is secondary while be used as output end；If the secondary system when arriving zero sequence current mutual inductor pair by current direction of protective current mutual inductor is intermediate system, the transmission function phase of the intermediate system is；If the phase of the pumping signal is
Figure 2011103940886100001DEST_PATH_IMAGE004
；The phase of the response signal is
Figure 2011103940886100001DEST_PATH_IMAGE006
；In synchronization, when
Figure 2011103940886100001DEST_PATH_IMAGE008
When, the protective current mutual inductor and the zero sequence current mutual inductor are same polarity；In synchronization, when
Figure 2011103940886100001DEST_PATH_IMAGE010
When, protective current mutual inductor and zero sequence current mutual inductor are reversed polarity.
2. the zero sequence current mutual inductor detection method of small current system as described in claim 1, it is characterized in that: it is described using adaptive sine digital filter obtain the phase of the pumping signal of input current and the response signal of zero sequence current mutual inductor the following steps are included:
The input of S1, the adaptive sine digital filter are SIN function, described
Figure 2011103940886100001DEST_PATH_IMAGE014
For fundamental wave frequency,For positive integer,
Figure 2011103940886100001DEST_PATH_IMAGE018
For the function of time；
S2, by the SIN function
Figure 847903DEST_PATH_IMAGE012
With weight coefficient
Figure 2011103940886100001DEST_PATH_IMAGE020
It is multiplied, the weight coefficient
Figure 154119DEST_PATH_IMAGE020
It is actual valueEstimated value；
S3, by the SIN function
Figure 734005DEST_PATH_IMAGE012
Through
Figure 2011103940886100001DEST_PATH_IMAGE024
Phase shift become after cosine function again with weight coefficient
Figure 2011103940886100001DEST_PATH_IMAGE026
It is multiplied, the weight coefficient
Figure 883095DEST_PATH_IMAGE026
It is actual valueEstimated value；
S4, step S2 is added to obtain the output of the adaptive sine digital filter with the obtained two paths of signals of step S3
Figure 2011103940886100001DEST_PATH_IMAGE030
；
S5, adaptive sine digital filter output
Figure 511523DEST_PATH_IMAGE030
Inverted rear and real input signal
Figure 2011103940886100001DEST_PATH_IMAGE032
=
Figure 2011103940886100001DEST_PATH_IMAGE034
It is added, obtains the error of adaptive sine digital filter
Figure 2011103940886100001DEST_PATH_IMAGE036
, described
Figure 2011103940886100001DEST_PATH_IMAGE038
For positive integer；
S6, foundation error
Figure 921513DEST_PATH_IMAGE036
The mean square error of the adaptive sine digital filter can be obtained
Figure 2011103940886100001DEST_PATH_IMAGE040
；Pass through=
Figure 2011103940886100001DEST_PATH_IMAGE044
Figure 2011103940886100001DEST_PATH_IMAGE046
Figure 2011103940886100001DEST_PATH_IMAGE048
With
Figure 2011103940886100001DEST_PATH_IMAGE050
=
Figure 233153DEST_PATH_IMAGE046
Figure 2011103940886100001DEST_PATH_IMAGE054
Adjust weight coefficient
Figure 682588DEST_PATH_IMAGE020
With
Figure 973761DEST_PATH_IMAGE026
, make the mean square error of the adaptive sine digital filter
Figure 254570DEST_PATH_IMAGE040
Reach minimum；It is described
Figure 989308DEST_PATH_IMAGE042
For weight coefficient
Figure 785094DEST_PATH_IMAGE020
Weight coefficient adjusted, it is described
Figure 896270DEST_PATH_IMAGE050
For weight coefficientWeight coefficient adjusted,
Figure 999541DEST_PATH_IMAGE046
>0, 
Figure 282624DEST_PATH_IMAGE046
For adaptation coefficient, it to be used for control stability and convergence rate；
S7, acquirement are worked as
Figure 666332DEST_PATH_IMAGE040
Weight coefficient when minimum
Figure 984049DEST_PATH_IMAGE020
With
Figure 247540DEST_PATH_IMAGE026
, obtain
Figure 2011103940886100001DEST_PATH_IMAGE056
； 
Figure 2011103940886100001DEST_PATH_IMAGE058
For the phase of signal.
3. the zero sequence current mutual inductor detection method of small current system as claimed in claim 1 or 2, it is characterized in that: it is described using adaptive sine digital filter obtain the amplitude of the pumping signal of input current and the response signal of zero sequence current mutual inductor the following steps are included:
The input of S1, the adaptive sine digital filter are SIN function
Figure 893285DEST_PATH_IMAGE012
, describedFor fundamental wave frequency,
Figure 252908DEST_PATH_IMAGE016
For positive integer,For the function of time；
S2, by the SIN function
Figure 758025DEST_PATH_IMAGE012
With weight coefficient
Figure 998382DEST_PATH_IMAGE020
It is multiplied, the weight coefficient
Figure 986234DEST_PATH_IMAGE020
It is actual value
Figure 404577DEST_PATH_IMAGE022
Estimated value；
S3, by the SIN function
Figure 883968DEST_PATH_IMAGE012
Through
Figure 865700DEST_PATH_IMAGE024
Phase shift become after cosine function again with weight coefficient
Figure 497669DEST_PATH_IMAGE026
It is multiplied, the weight coefficient
Figure 273864DEST_PATH_IMAGE026
It is actual value
Figure 506131DEST_PATH_IMAGE028
Estimated value；
S4, step S2 is added to obtain the output of the adaptive sine digital filter with the obtained two paths of signals of step S3
Figure 839024DEST_PATH_IMAGE030
；
S5, adaptive sine digital filter output
Figure 574768DEST_PATH_IMAGE030
Inverted rear and real input signal=
Figure 54476DEST_PATH_IMAGE034
It is added, obtains the error of adaptive sine digital filter
Figure 925480DEST_PATH_IMAGE036
, describedFor positive integer；
S6, foundation errorThe mean square error of the adaptive sine digital filter can be obtained
Figure 778271DEST_PATH_IMAGE040
；Pass through
Figure 905495DEST_PATH_IMAGE042
=
Figure 553514DEST_PATH_IMAGE044
Figure 655463DEST_PATH_IMAGE046
Figure 2011103940886100001DEST_PATH_IMAGE060
With
Figure 208673DEST_PATH_IMAGE050
=
Figure 687058DEST_PATH_IMAGE052
Figure 189584DEST_PATH_IMAGE046
Adjust weight coefficient
Figure 565256DEST_PATH_IMAGE020
With
Figure 847333DEST_PATH_IMAGE026
, make the mean square error of the adaptive sine digital filter
Figure 532261DEST_PATH_IMAGE040
Reach minimum；It is described
Figure 976012DEST_PATH_IMAGE042
For weight coefficient
Figure 316864DEST_PATH_IMAGE020
Weight coefficient adjusted, it is described
Figure 386320DEST_PATH_IMAGE050
For weight coefficientWeight coefficient adjusted,
Figure 478089DEST_PATH_IMAGE046
>0, 
Figure 102975DEST_PATH_IMAGE046
For adaptation coefficient, it to be used for control stability and convergence rate；
S7, acquirement are worked as
Figure 913805DEST_PATH_IMAGE040
Weight coefficient when minimumWith
Figure 358878DEST_PATH_IMAGE026
, obtain
Figure 2011103940886100001DEST_PATH_IMAGE062
；
Figure 2011103940886100001DEST_PATH_IMAGE064
For the amplitude of signal.
4. the zero sequence current mutual inductor detection method of small current system as claimed in claim 3, it is characterized in that: further including the steps that the frequency for adjusting high-frequency current signal makes the reactance of cable and direct-to-ground capacitance reach resonant state.
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