CN103487665B - Measurement primary cut-out equalizing capacitance test method - Google Patents
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Abstract
The present invention provides a kind of measurement primary cut-out equalizing capacitance test method.In kaolinite current conversion station SUZHOU A REVA high-voltage switch gear measure its dielectric loss when test data bigger than normal, but when equipment is taken apart the laboratory test for being put into sealing, test data recovers normal, therefore determines do not pulling open chopper side grounding switch and using reverse wiring screen method and utilizing alien frequencies method（Avoid Hz noise）Tested, equalizing capacitor electric capacity and dielectric loss measurement is carried out using experiment power supply frequency is changed with the method for improving experiment power supply voltage, realize that the shielding to live electromagnetic interference, equalizing capacitor dielectric loss have carried out theory analysis with the variation relation of voltage first to change experiment power supply frequency, to understand the dielectric characteristic of power equipment and internal dielectric loss variation tendency, tool is of great significance.
Description
Technical field：The present invention provides a kind of measurement primary cut-out equalizing capacitance test method.
Background technology：Breaker fracture capacitor, also known as equalizing capacitor, on the fracture with chopper mainly in parallel,
So that the voltage of each fracture of chopper is uniform, preferably realize that arc extinguishing is acted on.For without the fracture before parallel equalizing capacitor device
Equivalent circuit is as shown in Figure 1：Wherein C1=C2, C0For stray capacitance, C in practice0Compare C1、C2Much bigger, so, C1Hold on fracture
The voltage that receives is than C2Upper much bigger, cause voltage to distinguish pole voltage un-balance on fracture, it is difficult to arc extinguishing.Add on fracture and press
Equivalent circuit after capacitor such as Fig. 2：Now in C1And C2On voltage substantially the same so that the voltage between fracture point
Cloth is pressed with beneficial to arc extinguishing.
The essential structure of equalizing capacitor is similar with the structure of coupled capacitor device, is typically with porcelain overcoat, and element is complete
Portion connects, and inside changes and the metal bellowss of change in volume with running temperature with compensation impregnating agent.Its material, technique and matter
Amount is essentially identical with other capacitors, but is usually present the problems such as interference is big, data are untrue.Widely apply in high pressure equipment
Insulant, the selection of material, manufacturing process, insulation ag(e)ing under severe operating condition etc. be likely to accidents caused, wherein
Very big the reason for is that manufacturing process defect, medium make moist and aging, and in high-potting, common manifestation increases for the loss of medium.
In the presence of compared with strong interferers, being difficult with traditional method makes measurement error be reduced to License Value, frequently results in measurement knot
Really insincere.
Content of the invention：
Goal of the invention：The present invention provides a kind of measurement primary cut-out equalizing capacitance test method, its objective is to solve with
Toward mode existing for the undesirable problem of effect.
Technical scheme：The present invention is achieved by the following technical solutions：
A kind of measurement primary cut-out equalizing capacitance test method, it is characterised in that:The step of the method, is as follows:Assume electricity
Pressure signal is u (t), and current signal is i (t), and expression formula is respectively
In formula：I0And U0Respectively electric current and voltage DC component；ω is fundamental wave angular frequency；Ik1And Ik2Respectively electric current k
The sinusoidal and cosine component of subharmonic；Uk1And Uk2The sinusoidal and cosine component of respectively voltage k subharmonic;
fsIt is defined as corresponding signal and adopts frequency, TsFor 1/fsThen corresponding sampling time interval, then cycle of fundamental wave：
T=(N+M+e) Ts（15）
Wherein N, M be integer, L=N+M；E is the numerical value more than 0 less than 1, and M and e only deviates preferable in signal frequency
Exist during frequency;
Dielectric loss angle numerically depends on relative ratio, so calculating for convenience, is multiplied by one before fundamental signal respectively
Individual coefficient, as follows：
In formula：I (n)=I (nTs)；U (n)=U (nTs), then dielectric loss angle is
For being an integration required by formula (17)～(20), and obtain in the discrete case, formula (17)～
(20) interpolation method, interpolation method is added to construct a suitable formula, by this using trapezoidal interpolation integral formula in
After method, obtained component is as follows：
In formula：ISAnd USI (t) and u (t) respectively corresponding to the T moment, according to I (L), I (L+1) and U (L), U (L+1)
Linear interpolation is obtained：
IS=I (L)+e [I (L+1)-I (L)] (22)
US=U (L)+e [U (L+1)-U (L)] (23)
Advantage and effect：The present invention provides a kind of measurement primary cut-out equalizing capacitance test method.In kaolinite current conversion station
SUZHOU A REVA high-voltage switch gear when its dielectric loss is measured test data bigger than normal, but when equipment being taken apart the indoor examination for being put into sealing
When testing, test data recovers normal, therefore determines do not pulling open chopper side grounding switch and adopting reverse wiring screen method simultaneously
And utilize alien frequencies method（Avoid Hz noise）Tested, using the side for changing experiment power supply frequency and raising experiment power supply voltage
Method is realized to live electromagnetic interference to changing experiment power supply frequency first carrying out equalizing capacitor electric capacity and dielectric loss measurement
Shielding, equalizing capacitor dielectric loss have carried out theory analysis with the variation relation of voltage, understand the dielectric characteristic of power equipment
With internal dielectric loss variation tendency, tool is of great significance.
Description of the drawings：
The fracture equivalent circuit of the non-parallel equalizing capacitor devices of Fig. 1.
Fig. 2 is plus the equivalent circuit after equalizing capacitor.
Fig. 3 insulation equivalent circuits and its vector diagram.
Fig. 4 Schering bridge equivalent circuits
The digitized on-line monitoring schematic diagram of Fig. 5 dielectric loss.
Specific embodiment：The present invention is described further below in conjunction with the accompanying drawings：
As shown in figure 1, the present invention provides a kind of measurement primary cut-out equalizing capacitance test method, the method is tan δ's
Processing method, another mainly adopt traditional fundamental waves phase detachment method, and its ultimate principle is as follows：
Hypothesis voltage signal is u (t), and current signal is i (t), and expression formula is respectively
In formula：I0And U0Respectively electric current and voltage DC component；ω is fundamental wave angular frequency；Ik1And Ik2Respectively electric current k
The sinusoidal and cosine component of subharmonic；Uk1And Uk2The sinusoidal and cosine component of respectively voltage k subharmonic.
fsIt is defined as corresponding signal and adopts frequency, TsFor 1/fsThen corresponding sampling time interval, then cycle of fundamental wave：
T=(N+M+e) Ts（15）
Wherein N, M be integer, L=N+M；E is the numerical value more than 0 less than 1, and M and e only deviates preferable in signal frequency
Exist during frequency.
Dielectric loss angle numerically depends on relative ratio, so calculating for convenience, is multiplied by one before fundamental signal respectively
Individual coefficient, as follows：
In formula：I (n)=I (nTs)；U (n)=U (nTs).Then dielectric loss angle is
It is sufficient that sampling to signal, a cycle.By formula (17) to (21), amount of calculation can be caused substantially to drop
Low, for the great situation of sampled data output, this method is particularly important.
For being an integration required by formula (17)～(20), and obtain in the discrete case, the mistake for causing
Difference is larger unavoidably, in order to reduce this impact, needs to add appropriate interpolation method in formula.Accumulated using trapezoidal interpolation herein
Point formula, mainly constructs a suitable formula by experience, by this method after, obtained component is as follows：
In formula：ISAnd USI (t) and u (t) respectively corresponding to the T moment, according to I (L), I (L+1) and U (L), U (L+1)
Linear interpolation is obtained：
IS=I (L)+e [I (L+1)-I (L)] (22)
US=U (L)+e [U (L+1)-U (L)] (23)
As can be seen that the result that this method is calculated is to reduce a part of error.
The method for effectively reducing the error of test data when primary cut-out equalizing capacitance is measured using the method can be
Popularized in later work, later work can play help, found some indiscoverable defects or problem,
Produce certain Social and economic benef@.
Design process of the invention is described in detail below：
The improvement of measuring method
Under alternating voltage effect, the insulation characterisitic of capacitance type equipment is as shown in Figure 3.Flow through medium electric current I can regard as by
Capacitance current component ICXWith resistor current component IRXTwo parts are constituted, usual ICX>>IRX.The loss of medium is different due to mechanism,
Leakage can be divided into and lead loss, three kinds of primitive forms of polarization loss and shelf depreciation.Dielectric loss angle, leakage current and dielectric electricity
Appearance is to weigh three characteristic quantities of insulation degree.And dielectric loss angle tangent (tan δ) be only dependent upon material characteristic and and material
The size and dimension of material is unrelated, is therefore very effective using tan δ as the parameter of equipment integral insulation situation.
According to Fig. 3 it is known that：
It can be seen that, dielectric loss angle tangent is only relevant with the attribute of material itself, and shape, size etc. are unrelated.
Traditional power failure test is the tan δ and C for detecting capacitance type equipment using Schering bridge method mostlyX, advantage is wiring
Simply, accuracy of measurement is high, has the disadvantage high voltage standard capacitor high cost, is difficult to transport, be difficult on-site on-line measurement, specifically
Schematic diagram as shown in figure 4, in, CxAnd RxFor the equivalent shunt capacitance and resistance of product to be tested, R3And R4Represent electric arm ratio arms, Cn
For balancing the standard of sample electric capacity Cx, C4Variable capacitance for balancing loss angle tangent.According to capacitive balance principle, as follows when having
When relation：
ZxZ4=ZnZ3（2）
In formula, Zx、Zn、Z3、Z4It is the sample resistance of electric bridge, standard capacitor impedance and bridge arm Z respectively3、Z4Impedance,
According to upper relation of plane, can obtain as drawn a conclusion：
Although off-line checking method can need substantial amounts of people with the dielectric loss of reasonable test to equipment, offline inspection
Power material resources, it is difficult to accomplish maintenance in time, while live capacity of resisting disturbance is weaker, so, at present according to this basic principle, send out
A series of On-line Measuring Method is put on display.
Digital dielectric loss angle measuring method online
The electric current I passed through in capacitance type equipment insulation previous phase angle φ super than its voltage U, according to dielectric loss angle δ
Define the complementary angle that its value is φ.Due to the usual very little of capacitance type equipment δ-value, therefore the accuracy for measuring φ or δ is proposed higher
Requirement.The disposal ability of traditional raising hardware device is than relatively limited, because level of hardware and manufacture skill at this stage
Art hook, in the period of certain under can not possibly obtain too big raising, therefore it is necessary to be algorithmically correspondingly improved.
It is current study hotspot that how research improves the algorithm of signal handling capacity, only can just realize in this way final
Fault diagnosis.
According to the ultimate principle of Fig. 3 it is recognised that flowing through the voltage Us of the electric current I than two ends of insulating of capacitance type equipment insulation
Advanced a phase angle φ, δ=pi/2-φ, because capacitance type equipment δ ordinarily be about 0.001～0.02rad, therefore to measuring φ
Or the accuracy of δ proposes higher requirement.As traditional power failure detection method cannot meet requirement, so needing to implement
On-line monitoring, ultimate principle figure such as Fig. 5 of on-line monitoring system show, as can be seen that mainly including hardware and software two in figure
Part, hardware facility and existing scientific and technological production capacity directly related, performance carries limited height, so key task is follow-up
On signal processing and analyzing algorithm, it is to improve the important means of tan δ accuracies of measurement using high accuracy data processing method.Main
If carrying out Orthogonal Decomposition with software (such as fast Fourier transform, correlation function algorithm and inner product of vector method) to leakage current, with
Try to achieve dielectric loss angle.In order to improve accuracy, degree of stability and the resolution of measurement, corresponding filtering is taken to sampled value and is calculated
Method, mainly has the following aspects：
(1) pretreatment of signal is carried out using Wavelet Transform, this method increases coagulation link, computationally intensive,
The calculating time is long, needs the processor of fast operation realize measurement in real time.
(2) Zero-cross comparator method, the method are insensitive to frequency fluctuation, but are affected by harmonic wave and drift larger.
(3) fundamental harmonic separation algorithm, the method are used for the digitized measurement of apparatus insulated dielectric loss angle, using fast Flourier
Conversion (FFT), calculating speed is fast, amount of calculation is little, but sample frequency can be caused when system frequency fluctuates to differ with signal frequency
Cause, resulting spectrum leakage effect and fence effect, can especially affect the measurement of loss angle.
Zero-cross comparator method
Zero-cross comparator method is that two frequencies of measurement are identical, and amplitude is equal, the phase angle difference between the little sine wave of phase angle difference
Method, two sine waves for meeting above-mentioned condition can be expressed as：
U1=A1sin wt;U2=A2sin(wt+ψ) （7）
The voltage difference at so any moment is：
U3=U2-U1=A2sin(wt+ψ)-A1sin wt （8）
Due to:
A1=A2=A（9）
It is possible to obtain：
U3=A [sin (wt+ ψ)-sin wt]=B cos (wt+ ψ/2)（10）
Have above：
B=2A sin (ψ/2)（11）
As t=0, there is U3=A sin ψs, can finally obtain：
ψ=arcsin (U3/A) （12）
The online insulator arrangement e measurement technology of these digitizeds key issue ripe not enough is that leakage current only has milli
Peace level, or even harmonic current or interference signal is less than, such useful signal is far below the linear work area of A/D converter
, the nonlinear system that acquisition system is time-varying is caused, even if processing to sampled signal plus filtered Software, sampling still has
Have serious non-linear, substantially reduce accuracy, degree of stability and the resolution of measurement.
The present invention is obtained by the analysis to above-mentioned drawback, and the present invention solves asking existing for conventional mode well
Topic.
Claims (2)
1. one kind measures primary cut-out equalizing capacitance test method, it is characterised in that:The step of the method, is as follows:Voltage signal
For u (t), current signal is i (t), and expression formula is respectively
In formula：I0And U0Respectively electric current and voltage DC component；ω is fundamental wave angular frequency；Ik1And Ik2Respectively electric current k time is humorous
The sinusoidal and cosine component of ripple；Uk1And Uk2The sinusoidal and cosine component of respectively voltage k subharmonic；U (t), i (t) are gathered
The voltage applied when being surveyed primary cut-out equalizing capacitance and corresponding output current；
fsIt is defined as corresponding signal sampling frequencies, TsFor 1/fsThen corresponding sampling time interval, then cycle of fundamental wave：
T=(N+M+e) Ts(15)
Wherein N, M be integer, L=N+M；E is the numerical value more than 0 less than 1, and M and e is only in signal frequency deviation ideal frequency
When exist；
Dielectric loss angle numerically depends on relative ratio, so calculating for convenience, being multiplied by one before fundamental signal respectively is
Number, as follows：
In formula：I (n)=I (nTs)；U (n)=U (nTs), then dielectric loss angle is
2. according to claim 1 measurement primary cut-out equalizing capacitance test method, it is characterised in that:
For being an integration required by formula (16)～(19), and obtain in the discrete case, in formula (16)～(19)
Middle addition interpolation method, take n-th and n+1 subharmonic are averagely worth to formula (21), and interpolation method adopts trapezoidal interpolation integral
Formula, constructs a suitable formula, by this method after, obtained component is as follows：
In formula：ISAnd USI (t) and u (t) respectively corresponding to the T moment, linear according to I (L), I (L+1) and U (L), U (L+1)
Interpolation is obtained：
IS=I (L)+e [I (L+1)-I (L)] (22)
US=U (L)+e [U (L+1)-U (L)] (23).
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| CN103777079A (en) * | 2014-02-07 | 2014-05-07 | 国网上海市电力公司 | Anti-interference parameter integration testing device for ultra-high voltage line |
| CN105021980B (en) * | 2015-06-23 | 2016-11-16 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | AC filter and breaker double-fracture voltage's distribiuting characteristic evaluation system and method |
| CN106019101B (en) * | 2016-06-24 | 2018-02-23 | 兴义供电局 | A kind of Electric Power Equipment Insulation state evaluating method |
| CN108919109B (en) * | 2018-07-10 | 2021-05-18 | 武汉大学 | Dynamic voltage-sharing simulation test method for multi-fracture high-voltage direct-current quick mechanical switch |
| CN113325305B (en) * | 2021-06-03 | 2024-09-13 | 贵州电网有限责任公司 | High-voltage electric test wiring device of 500kV circuit breaker and use method thereof |
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| SU461391A1 (en) * | 1972-03-10 | 1975-02-25 | Уральский политехнический институт им.С.М.Кирова | Device for testing high-voltage switches |
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