CN104808071A - Three-phase alternating current electric inductance measuring and testing instrument - Google Patents

Abstract

The invention relates to a three-phase alternating current electric inductance measuring and testing instrument. The three-phase alternating current electric inductance measuring and testing instrument comprises a 300KVA three-phase alternating current inverter power supply or an induction regulator (1), a U-phase flexible current sensor (2), a V-phase flexible current sensor (3), a W-phase flexible current sensor (4), a U-phase differential voltage probe (5), a V-phase differential voltage probe (6), a W-phase differential voltage probe (7), a four-channel high-speed high-bandwidth acquisition card (8), a two-channel high-speed high-bandwidth acquisition card (9) and a PC (Personal Computer) (10). The three-phase alternating current electric inductance measuring and testing instrument has the advantages of being good in human-computer interaction, high in measuring and testing accuracy, low in cost and the like and can be widely used in the field of inductance measuring and testing.

Description

Three-phase alternating current electric inductance measuring-testing instrument

Technical field

The present invention relates to three-phase alternating current electric inductance measuring-testing instrument.

Background technology

Electric system using compensation Capacitor banks improves power factor.The displacement volume of reactive compensation capacitor is large, switches frequent.For the reliability of support equipment, need regularly detect.The Problems existing single capacitor electrode capacitance in Shunt Capacitor Unit measured by capacitor and inductor tester during for substation field and developing specially.Traditional detection method is removed by electric capacity bus-bar, then measures with capacitance meter.This method remedial efforts amount is large, also easily causes the damage of electric capacity; Therefore, for overcoming the above problems, urgently research and develop a automatic electric inductance measuring-testing instrument newly.

Summary of the invention

For overcoming the above problems, the present invention relates to three-phase alternating current electric inductance measuring-testing instrument, described three-phase alternating current electric inductance measuring-testing instrument comprises: 300kVA three-phase alternating current variable-frequency power sources or induction voltage regulator (1), U phase flexible current sensor (2), V phase flexible current sensor (3), W phase flexible current sensor (4), U phase differential voltage probe (5), V phase differential voltage probe (6), W phase differential voltage probe (7), four-way very fast high-bandwidth adopts card (8), two passage very fast high-bandwidth adopt card (9) and PC (10);

The first end of described U phase flexible current sensor (2), the first end of V phase flexible current sensor (3) and the first end of W phase flexible current sensor (4) are connected the U phase of described 300kVA three-phase alternating current variable-frequency power sources or induction voltage regulator (1), V phase and W phase respectively;

Second end of described U phase flexible current sensor (2) is connected one end of U phase differential voltage probe (5) by the resistance Ru of series connection with inductance L u, described U phase differential voltage four-way very fast high-bandwidth described in the other end of (5) and the three-terminal link of described U phase flexible current sensor (2) of popping one's head in adopts card (8);

Second end of described V phase flexible current sensor (3) is connected one end of V phase differential voltage probe (6) by the resistance Rv of series connection with inductance L v, described V phase differential voltage four-way very fast high-bandwidth described in the other end of (6) and the three-terminal link of described V phase flexible current sensor (3) of popping one's head in adopts card (8);

Second end of described W phase flexible current sensor (4) is connected one end of W phase differential voltage probe (7) by the resistance Rw of series connection with inductance L w, described W phase differential voltage two passage very fast high-bandwidth described in the other end of (7) and the three-terminal link of described W phase flexible current sensor (7) of popping one's head in adopt card (9);

Card (8) adopted by described 300kVA three-phase alternating current variable-frequency power sources or induction voltage regulator (1), four-way very fast high-bandwidth, two passage very fast high-bandwidth are adopted card (9) and all connected described PC (10).

It is good that the present invention has man-machine interaction, and the advantages such as measuring accuracy is high, and cost is low, can be widely used in inductance measurement field.

Accompanying drawing explanation

Describe exemplary embodiment of the present invention in more detail by referring to accompanying drawing, above and other aspect of the present invention and advantage will become and more be readily clear of, in the accompanying drawings:

Fig. 1 is AC inductance tester hardware principle sketch of the present invention;

Fig. 2 is three-phase alternating current inductance precision analysis figure of the present invention.

The Reference numeral of Fig. 1 is as follows:

1,300kVA three-phase alternating current variable-frequency power sources or induction voltage regulator; 2, U phase flexible current sensor; 3, V phase flexible current sensor; 4, W phase flexible current sensor; 5, U phase differential voltage probe; 6, V phase differential voltage probe; 7, W phase differential voltage probe; 8, four-way very fast high-bandwidth adopts card; 9, two passage very fast high-bandwidth adopt card; 10, PC.

Note: the collection control line that dotted line system power supply and capture card are connected with PC.

Embodiment

Hereinafter, more fully the present invention is described now with reference to accompanying drawing, various embodiment shown in the drawings.But the present invention can implement in many different forms, and should not be interpreted as being confined to embodiment set forth herein.On the contrary, provide these embodiments to make the disclosure will be thoroughly with completely, and scope of the present invention is conveyed to those skilled in the art fully.

Hereinafter, with reference to the accompanying drawings exemplary embodiment of the present invention is described in more detail.

As shown in Figure 1, described three-phase alternating current electric inductance measuring-testing instrument comprises: 300kVA three-phase alternating current variable-frequency power sources or induction voltage regulator (1), U phase flexible current sensor (2), V phase flexible current sensor (3), W phase flexible current sensor (4), U phase differential voltage probe (5), V phase differential voltage probe (6), W phase differential voltage probe (7), four-way very fast high-bandwidth adopts card (8), two passage very fast high-bandwidth adopt card (9) and PC (10);

The first end of described U phase flexible current sensor (2), the first end of V phase flexible current sensor (3) and the first end of W phase flexible current sensor (4) are connected the U phase of described 300kVA three-phase alternating current variable-frequency power sources or induction voltage regulator (1), V phase and W phase respectively;

Second end of described U phase flexible current sensor (2) is connected one end of U phase differential voltage probe (5) by the resistance Ru of series connection with inductance L u, described U phase differential voltage four-way very fast high-bandwidth described in the other end of (5) and the three-terminal link of described U phase flexible current sensor (2) of popping one's head in adopts card (8);

Second end of described V phase flexible current sensor (3) is connected one end of V phase differential voltage probe (6) by the resistance Rv of series connection with inductance L v, described V phase differential voltage four-way very fast high-bandwidth described in the other end of (6) and the three-terminal link of described V phase flexible current sensor (3) of popping one's head in adopts card (8);

Second end of described W phase flexible current sensor (4) is connected one end of W phase differential voltage probe (7) by the resistance Rw of series connection with inductance L w, described W phase differential voltage two passage very fast high-bandwidth described in the other end of (7) and the three-terminal link of described W phase flexible current sensor (7) of popping one's head in adopt card (9);

Card (8) adopted by described 300kVA three-phase alternating current variable-frequency power sources or induction voltage regulator (1), four-way very fast high-bandwidth, two passage very fast high-bandwidth are adopted card (9) and all connected described PC (10).

The course of work of three-phase alternating current electric inductance measuring-testing instrument of the present invention is as follows:

(1) according to rated current and the voltage determination power resistor numerical value of inductance to be measured, inductance to be measured and pull-up resistor is accessed by Fig. 1;

(2) PC testing software sends control command, and three phase frequency changing power is started shooting, 2 seconds at the latest, load to be measured should there is stable output, now software triggers two pieces of capture cards and gathers UVW three-phase totally six road voltage and current signals simultaneously, acquisition time about 20 cycles, 0.4 second.Control power supply shutdown subsequently;

(3) utilize collection signal to adopt Difference Calculation principle or Levenberg-Marquardt algorithm to calculate the inductance of each branch road of three pole reactor respectively, draw current/voltage inductance curve;

(4) real-time generation and the print job afterwards of data base querying, amendment, insertion, inquiry and deletion work and product form is completed.

Core component index used in the present invention is as follows:

(1) three-phase 300KVA variable-frequency power sources ()

This power acquisition separate type output isolated power supply transformer device structure, the desirable single-phase use of three-phase; High precision frequency-and voltage-stabilizing, knob quick adjustment voltage, frequency, can directly regulate by bringing onto load online; There is workload-adaptability strong, output waveform quality better, good man-machine interface, simple to operate, the advantages such as volume is little, lightweight.

Input phase: three-phase and four-line

Input voltage: 380V ± 15%

Incoming frequency: 50HZ/60Hz ± 5Hz

Export phase place: three-phase and four-line

Output voltage: 0 ~ 1000V is adjustable

Output frequency: 50/60/100/200Hz (40-70Hz continuously adjustabe)

Export maximum current: 0 ~ 2000A is adjustable

Output overloading ability: 120%30s, 200%10s, 300%5s

Frequency stability: frequently fixed≤± 0.01%, frequency modulation≤± 0.1%

Waveform distortion: THD≤3%

Power factor: 0.85

Reaction time :≤2ms

Communication interface: RS232/485 interface can be matched

Principle of work: IGBT/SPWM sinusoidal pulse width modulation mode

Defencive function: overcurrent protection, overvoltage protection, short-circuit protection, overload protection, open-phase protection

(2) three-phase 300KVA induction voltage regulator ()

Input phase: three-phase and four-line

Input voltage: 380V

Incoming frequency: 50HZ

Export phase place: three-phase and four-line

Output voltage: 0 ~ 1000V is adjustable

Output frequency: 50Hz

Export maximum current: 0 ~ 1000A is adjustable

Waveform distortion: without additional waveform distortion

Power factor: 0.95

The strain time: 0.2 ~ 0.5s

Being compared as follows of variable-frequency power sources and pressure regulator:

1) variable-frequency power sources controls the switch of power supply by interface by PC host software, working time and arbitrarily adjust voltage; Pressure regulator cannot;

2) variable-frequency power sources is easy and simple to handle, and pressure regulator can only manual operation;

3) pressure regulator volume is large, Heavy Weight, and variable-frequency power sources is then contrary, removable.

4) export can not frequency conversion for pressure regulator, and output quality is poor.

5) variable-frequency power sources is more expensive, and price is 3 to 4 times of pressure regulator.

(3) Pico Scope 5243A capture card (two passages, a piece).

(4) Pico Scope 5443A capture card (four-way, a piece).

(5) universal PC parameter ()

Liquid crystal display: >=14 cun

Internal memory DDR3: >=4G,

Solid state hard disc: >=200G

USB: >=4

(6) N1015A differential voltage probe (three)

1. feature:

This probe provides the instrument of a safety to use to all oscillographs, it can be changed the differential voltage (≤1500VPEAK) inputted by height and enter a low-voltage (≤1.5V), and display waveform is on oscillograph, frequency of utilization, up to 100MHz, is very applicable to large power test, research and development uses.Differential probe exports and indicates is the relative attenuation of design in the input impedance of operation oscillograph 1M Ω, is just 2 times amount when use 50 Ω adaptation enters damping capacity.This differential probe, also the PL-10 impedance transducer that the said firm produces is chosen, the range of application of differential test probe-more accurate actual measurement magnitude of voltage (oscillograph degree of accuracy is 1%, about accurate 10 times of digital electric meter) can be observed on ammeter can be extended.

2. specification:

(1) frequency range: DC-100MHz

(2) decay: × 100 and × 1000

(3) degree of accuracy: +/-1%

(4) input voltage range (DC+AC PEAK TO PEAK)

≤ +/-150Vfor × 100, (about 230V RMS or DC)

≤ +/-1500Vfor × 1000, (about 460V RMS or DC)

≤ 1400Vp-p for × 200, (about 450V RMS or DC)

(5) maximum input voltage is allowed:

The highest differential voltage: 1500V (DC+AC PEAK TO PEAK)

Single-ended to ceiling voltage between earth terminal: 1500V RMS

(6) input impedance:

Differential: 54M Ω/1.2pF

Single-ended input impedance between earth terminal: 27M Ω/2.3pF

(7) output voltage :≤+/-1.4V

(8) output impedance: 50 Ω

(9) rise time:

7ns for × 50 and × 200

14ns for×20

(10) squelch rate:

60Hz：＞80dB；100Hz：＞60dB；1MHz：＞50dB

(11) external 9V DC power supply is specified

(12) power consumption: maximum power consumption 35mA (0.4 watt)

(7) DK-3500 flexible current probe (three)

1. feature:

This probe can export by transient state ± 7V peak-to-peak value, directly accesses.

2. parameter:

Peak point current: 3500A

Sensitivity: 2mV/A

Bandwidth: 0.2Hz-20MHz

Precision: 1%

Rate of change: 20kA/us

Output mode: BNC (50 Ω)

Input impedance: 100k Ω

Precision analysis of the present invention comprises two schemes: Difference Calculation principle and Levenberg-Marquardt algorithm

(1) the first scheme: Difference Calculation principle.

Here a certain phase branch road is only considered, such as U branch road.All the other two branch roads are similar.

Two directly measured quantities are inductance both end voltage u (its effective value is U) and i (its effective value is I) accuracy requirement, and to be all 1%, eight precision of adopting card be: 12 precision of adopting card are: adopt card for eight 12 all can meet the demands, consider from the angle retaining certain allowance, consider employing 12 card.

For interchange L-R circuit, ignore inductance self-resistance, its current/voltage difference is 90 °.Suppose that voltage is standard sine amount then its electric current is cosine amount the promising sinusoidal quantity of differential be illustrated in fig. 2 shown below.

By accuracy requirement, have: σ _u=U _max× θ _u=1000 × 1%=10V, σ _i=I _max× θ _i=2000 × 1%=20A.

By computing formula the standard deviation of inductance can be calculated.

If capture card acquisition interval is Δ t, then current differential using differential represents, namely suppose that Δ t can accurately measure, i ' is i _{t+ Δ t}, i _tdeng the function of two directly measured quantities, i.e. i '=i ' (i _{t+ Δ t}, i _t), thus the standard deviation of i ' can be obtained:

$\begin{array}{c}{\mathrm{\σ}}_{i^{\′}}=\sqrt{{\left(\frac{\∂i^{\′}}{{\∂i}_{t+\mathrm{\Δt}}}\right)}^2{\mathrm{\σ}}_{i_{t+\mathrm{\Δt}}}^2+{\left(\frac{\∂i^{\′}}{\∂i_t}\right)}^2{\mathrm{\σ}}_{i_t}^2}\\ =\sqrt{{\left(\frac{1}{\mathrm{\Δt}}\right)}^2{\mathrm{\σ}}_{i_{t+\mathrm{\Δt}}}^2+{(-\frac{1}{\mathrm{\Δt}})}^2{\mathrm{\σ}}_{i_t}^2}\\ \begin{array}{cc}\≈\frac{1}{\mathrm{\Δt}}\·\sqrt{2{\mathrm{\σ}}_i^2}=\frac{\sqrt{2}{\mathrm{\σ}}_i}{\mathrm{\Δt}}& ({\mathrm{\σ}}_i={\mathrm{\σ}}_{i_{t+\mathrm{\Δt}}}={\mathrm{\σ}}_{i_t})\end{array}\end{array}$

The Direct calculation formulas of inductance is: l is the function of two directly measured quantities such as u, i ' wait, i.e. L=L (u, i ').

$\frac{\∂L}{\∂u}=\frac{1}{i^{\′}},\frac{\∂L}{\∂i^{\′}}=-\frac{u}{i^{\′2}}$

$\begin{array}{c}{\mathrm{\σ}}_L=\sqrt{{\left(\frac{\∂L}{\∂u}\right)}^2{\mathrm{\σ}}_u^2+{\left(\frac{\∂L}{\∂i^{\′}}\right)}^2{\mathrm{\σ}}_{i^{\′}}^2}\\ =\sqrt{{\left(\frac{1}{i^{\′}}\right)}^2{\mathrm{\σ}}_u^2+{(-\frac{u}{{\left(i^{\′}\right)}^2})}^2{\mathrm{\σ}}_{i^{\′}}^2}\\ \begin{array}{cc}\widetilde{=}\frac{1}{i^{\′}}\·\sqrt{{\mathrm{\σ}}_u^2+{\left(\frac{u}{i^{\′}}\right)}^2{\mathrm{\σ}}_{i^{\′}}^2}=\frac{1}{i^{\′}}\·\sqrt{{\mathrm{\σ}}_u^2+2\·{\left(\frac{L}{\mathrm{\Δt}}\right)}^2{\mathrm{\σ}}_i^2}& ({\mathrm{\σ}}_i={\mathrm{\σ}}_{i_{t+\mathrm{\Δt}}}={\mathrm{\σ}}_{i_t})\end{array}\end{array}$

From above formula, following several conclusions can be released with guide data collection and data processing:

1) standard deviation of inductance and the differential of electric current are inversely proportional to, and for ensureing enough little standard deviation, sinusoidal quantity should be selected enough large, and as 0.5, that is the dash area of Fig. 2 is pickup area.

2) standard deviation and the current acquisition value of inductance and the standard deviation of voltage acquisition value become the relation of quadratic sum, now the sensor accuracy of large voltage on the market and big current is the highest also with regard to 1%, do not reach accuracy requirement of the present invention far away, therefore electric current and voltage data acquisition set value has to pass through filtering, the present invention considers that average smooth filtering and least squares filtering are to ensure precision, can arrive the grade of 1mV (1mA).

3) standard deviation of inductance and inductance value to be measured increase progressively relation, and inductance is large, and its variance must be large, but relative error impact is not very large.

4) standard deviation of inductance also becomes quadratic sum inverse ratio (direct ratio) relation with acquisition interval (acquisition rate), and acquisition rate is less, and its variance must be little, but should be too not little, the therefore constraint of Nyquist law.Generally getting acquisition rate is 10MHz.

When pressing shadow region image data, namely and during the μ F of L>=2, first quadratic sum item of the standard deviation of inductance namely voltage measurement contribution part can be ignored, be then reduced to further:

$\begin{array}{c}{\mathrm{\σ}}_L\≤2\·\sqrt{{\mathrm{\σ}}_u^2+2\·{\left(\frac{L}{\mathrm{\Δt}}\right)}^2{\mathrm{\σ}}_i^2}\\ =\frac{\sqrt{2{\mathrm{\σ}}_u^2+4\·{\left(\frac{L}{\mathrm{\Δt}}\right)}^2{\mathrm{\σ}}_i^2}}{2\mathrm{\πfI}}=\frac{L{\mathrm{\σ}}_i}{\mathrm{\πfI\Δt}}\end{array}$

Following formula can obtain the standard deviation of inductance by empirical data:

1) make L=0.1 μ F, supposing that Cai Kacai leads is 10M

$\begin{array}{c}{\mathrm{\σ}}_L=\frac{1}{i^{\′}}\·\sqrt{{\mathrm{\σ}}_u^2+2\·{\left(\frac{L}{\mathrm{\Δt}}\right)}^2{\mathrm{\σ}}_i^2}\\ =\frac{\sqrt{2{\mathrm{\σ}}_u^2+4\·{\left(\frac{L}{\mathrm{\Δt}}\right)}^2{\mathrm{\σ}}_i^2}}{2\mathrm{\πfI}}\\ \begin{array}{c}=\frac{\sqrt{2\×0.000001+4\×{\left(\frac{0.1}{0.1}\right)}^2\×0.000001}}{2\×3.14\×50\×2000}=3.9\×{10}^{-9}F\end{array}\end{array}$

${\mathrm{\θ}}_L=\frac{{\mathrm{\σ}}_L}{L}=\frac{3.9\×{10}^{-9}}{0.1\×{10}^{-6}}=3.9\%$

(1) make L=2000 μ F, it is 10M that same hypothesis Cai Kacai leads,

${\mathrm{\σ}}_L=\frac{\sqrt{2\×0.000001+4\×{\left(\frac{2000}{0.1}\right)}^2\×0.000001}}{2\×3.14\×50\×2000}=6.4\×{10}^{-2}F$

${\mathrm{\θ}}_L=\frac{{\mathrm{\σ}}_L}{L}=\frac{6.4\×{10}^{-5}}{2000\×\×{10}^{-6}}=3.2\%$

From above rough theory calculate, current error is the principal element affecting inductance error, as long as guarantee current error is within 1% and average smooth filtering and least squares filtering are considered in software process, the error that the first scheme Difference Calculation principle calculates inductance ensures in the scope of 3% it is no problem.

(2) first scheme: Levenberg-Marquardt algorithm.

Levenberg-Marquadt algorithm is most popular Nonlinear Least-Square Algorithm, and Chinese is the civilian Burger-Ma Kuaertefa of row.It is the algorithm utilizing gradient to ask maximum (little) value.It has the advantage of gradient method and Newton method simultaneously.When λ is very little, step-length equals Newton method step-length, and when λ is very large, step-length approximates the step-length of gradient descent method.Its application widely, as economics, management optimization, network analysis, optimal design, machinery or Electronic Design etc.

Consider funtcional relationship x=f (p), wherein p ∈ R ^{n × 1}parameter vector, x ∈ R ^{m × 1}close to actual value containing noise observation vector.Solve following minimization problem:

$p_{\mathrm{opt}}=\arg \underset{p}{\min }\left|\right|x-f\left(p\right)\left|\right|$

A given initial solution p _kconsider that f (p) is at p _kfirst approximation f (p near point _k+ δ _k)=f (p _k)+J _kδ _k, wherein J _kthat Jacobi matrix is at p _kthe value (cutting mapping) of point.Find next iteration point p _k+1=p _k+ δ _kmake:

$\left|\right|x-f\left(p_{k+1}\right)\left|\right|=\underset{{\mathrm{\δ}}_{p_k}}{\min }\left|\right|J_k\·{\mathrm{\δ}}_k-{\mathrm{\ϵ}}_k\left|\right|$

This minimization problem is exactly known J in essence _kand ε _k, solve determined linear equation J _kδ _k=ε _k.

In LM algorithm, be iterating through the damping factor λ that searching one is suitable each time _k, obtain the solution of this minimization problem:

${\left({\mathrm{\δ}}_k\right)}_{\mathrm{LM}}=(J_k^T{J}_k+{\mathrm{\λ}}_{k}I)J_k^T{\mathrm{\ϵ}}_k$

Calculation procedure:

Step 1: get initial point p ₀, stop control constant ε, calculate ε ₀=‖ x-f (p ₀) ‖, k:=0, λ ₀=10 ^-3, v=10 (also can be the number that other are greater than 1).

Step 2: calculate Jacobi matrix J _k, calculate structure increment normal equations ${\stackrel{\‾}{N}}_k\·{\mathrm{\δ}}_k=J_k^T{\mathrm{\ϵ}}_k.$

Step 3: solve increment normal equations and obtain δ _k

(1) if ‖ x-f is (p _k+ δ _k) ‖ < ε _k, then p is made _k+1=p _k+ δ _kif, ‖ δ _k‖ < ε, stops iteration, Output rusults; Otherwise make λ _k+1=λ _k/ v, forwards step 2 to.

(2) if ‖ x-f is (p _k+ δ _k) ‖>=ε _k, then λ is made _k+1=v λ _k, again separate normal equations and obtain δ _k, return step (1).

With reference to Fig. 1, gather voltage signal and the current signal i (at least 20 cycles, about 0.4 second) of a certain branch road, hypothesized model is:

Application Levenberg-Marquardt estimates four parameter: A _u, A _i, and effective value can be drawn like this through software process and the phase place of voltage leading current

There is following system of equations:

Resolve it, can obtain:

From above formula, as long as estimate: A _u, A _i, and just can calculate the intuition L of the inductance to be measured and straight resistance R of inductance to be measured.

Based on the angle of the thin item realization of each function and considering of this measuring system of rapid build, the present invention adopts LabVIEW virtual instrument platform to develop, and considers as follows:

(1) oscillograph function, can display waveform in real time during measurement.

(2) directly read the function of inductive data and can judge that whether it is qualified.

LabVIEW is the virtual instrument development platform based on G design language of National Instruments's exploitation, and its computing function can match in excellence or beauty with C language.Whether the differential scheme that inductance value provides by precision analysis trifle and Levenberg-Marquardt algorithm select excellent carrying out, and qualified with theoretical value multilevel iudge, can provide whether qualified conclusion by a pilot lamp.

(3) memory function, has the function of product information and detecting information storage.

The function that LabVIEW has special file I/O selects plate, and file processing is powerful.Product information and detecting information memory function can be completed by one page of tab.

(4) form have daily sheet, the moon form, year form function, also can according to condition query generation form; Form can export as excel file.

LabVIEW virtual instrument development platform has form to select plate, can complete corresponding various functions, can according to the daily sheet of enterprise side, the moon form, annual report tableau format or condition query generate needed for form, form can directly derive excel file.

(5) can make an amendment by authority, add, delete, query function.

Platform has database access function, each product information and test result are saved in database by the present invention, and a record format of database is: the product informations such as tester, name of product, product type, production code member, experiment numbers, product batch number, sampling instant, production time, customer name and voltage change ratio, error criterion, sampling cycle, voltage acquisition value, current acquisition value, inductance theoretical value, inductance calculated value, sampling rate, the selection of single-phase three-phase and error range etc.Amendment, interpolation, deletion, inquiry and more New function can be completed by demand, and can from database deduced image curve form, demonstrate a certain branch road Cai Ka bis-road signal: voltage signal u (t) and current signal i (t), and according to the inductance value L curve that above-mentioned algorithm provides.

(6) system can adopt Phototube Coupling.

The foregoing is only embodiments of the invention, be not limited to the present invention.The present invention can have various suitable change and change.All any amendments done within the spirit and principles in the present invention, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (5)

1. three-phase alternating current electric inductance measuring-testing instrument, is characterized in that:

Described three-phase alternating current electric inductance measuring-testing instrument comprises: 300kVA three-phase alternating current variable-frequency power sources or induction voltage regulator (1), U phase flexible current sensor (2), V phase flexible current sensor (3), W phase flexible current sensor (4), U phase differential voltage probe (5), V phase differential voltage probe (6), W phase differential voltage probe (7), four-way very fast high-bandwidth adopts card (8), two passage very fast high-bandwidth adopt card (9) and PC (10);

The first end of described U phase flexible current sensor (2), the first end of V phase flexible current sensor (3) and the first end of W phase flexible current sensor (4) are connected the U phase of described 300kVA three-phase alternating current variable-frequency power sources or induction voltage regulator (1), V phase and W phase respectively;

Second end of described U phase flexible current sensor (2) is connected one end of U phase differential voltage probe (5) by the resistance Ru of series connection with inductance L u, described U phase differential voltage four-way very fast high-bandwidth described in the other end of (5) and the three-terminal link of described U phase flexible current sensor (2) of popping one's head in adopts card (8);

Second end of described V phase flexible current sensor (3) is connected one end of V phase differential voltage probe (6) by the resistance Rv of series connection with inductance L v, described V phase differential voltage four-way very fast high-bandwidth described in the other end of (6) and the three-terminal link of described V phase flexible current sensor (3) of popping one's head in adopts card (8);

Second end of described W phase flexible current sensor (4) is connected one end of W phase differential voltage probe (7) by the resistance Rw of series connection with inductance L w, described W phase differential voltage two passage very fast high-bandwidth described in the other end of (7) and the three-terminal link of described W phase flexible current sensor (7) of popping one's head in adopt card (9);

Card (8) adopted by described 300kVA three-phase alternating current variable-frequency power sources or induction voltage regulator (1), four-way very fast high-bandwidth, two passage very fast high-bandwidth are adopted card (9) and all connected described PC (10).

2. three-phase alternating current electric inductance measuring-testing instrument as claimed in claim 1, is characterized in that:

The course of work of described three-phase alternating current electric inductance measuring-testing instrument is as follows:

(1) according to rated current and the voltage determination power resistor numerical value of inductance to be measured, inductance to be measured and pull-up resistor is accessed;

(2) PC testing software sends control command, three phase frequency changing power is started shooting, 2 seconds at the latest, load to be measured should there is stable output, now software triggers two pieces of capture cards and gathers UVW three-phase totally six road voltage and current signals simultaneously, acquisition time about 20 cycles, 0.4 second, control power supply shutdown subsequently;

(3) utilize collection signal to adopt Difference Calculation principle or Levenberg-Marquardt algorithm to calculate the inductance of each branch road of three pole reactor respectively, draw current/voltage inductance curve;

(4) real-time generation and the print job afterwards of data base querying, amendment, insertion, inquiry and deletion work and product form is completed.

3. three-phase alternating current electric inductance measuring-testing instrument as claimed in claim 1 or 2, is characterized in that:

Described four-way very fast high-bandwidth adopts card (8), two passage very fast high-bandwidth are adopted card (9) and adopted PicoScope 5443A capture card and Pico Scope 5243A capture card respectively.

4. three-phase alternating current electric inductance measuring-testing instrument as claimed in claim 2, is characterized in that:

The course of work of described Difference Calculation principle is as follows:

Two directly measured quantities are inductance both end voltage u (its effective value is U) and i (its effective value is I), suppose that voltage is standard sine amount then its electric current is cosine amount differential is sinusoidal quantity $i^{\&prime;}=\sqrt{2}\mathrm{\&omega;}I\sin \mathrm{\&omega;t};$

By accuracy requirement, have: σ _u=U _max× θ _u=1000 × 1%=10V, σ _i=I _max× θ _i=2000 × 1%=20A;

By computing formula the standard deviation of inductance can be calculated;

If capture card acquisition interval is Δ t, then current differential using differential represents, namely suppose that Δ t can accurately measure, i ' is i _{t+ Δ t}, i _tdeng the function of two directly measured quantities, i.e. i '=i ' (i _{t+ Δ t}, i _t), thus the standard deviation of i ' can be obtained:

$\begin{array}{c}{\mathrm{\&sigma;}}_{i^{\&prime;}}=\sqrt{{\left(\frac{\&PartialD;i^{\&prime;}}{\&PartialD;i_{t+\mathrm{\&Delta;t}}}\right)}^2{\mathrm{\&sigma;}}_{i_{t+\mathrm{\&Delta;t}}}^2+{\left(\frac{\&PartialD;i^{\&prime;}}{\&PartialD;i_t}\right)}^2{\mathrm{\&sigma;}}_{i_t}^2}\\ =\sqrt{{\left(\frac{1}{\mathrm{\&Delta;t}}\right)}^2{\mathrm{\&sigma;}}_{i_{t+\mathrm{\&Delta;t}}}^2+{(-\frac{1}{\mathrm{\&Delta;t}})}^2{\mathrm{\&sigma;}}_{i_t}^2}\\ \&ap;\frac{1}{\mathrm{\&Delta;t}}\&CenterDot;\sqrt{2{\mathrm{\&sigma;}}_i^2}=\frac{\sqrt{2}{\mathrm{\&sigma;}}_i}{\mathrm{\&Delta;t}},({\mathrm{\&sigma;}}_i={\mathrm{\&sigma;}}_{i_{t+\mathrm{\&Delta;t}}}={\mathrm{\&sigma;}}_{i_t})\end{array}$

The Direct calculation formulas of inductance is: l is the function of two directly measured quantities such as u, i ' wait, i.e. L=L (u, i ');

$\frac{\&PartialD;L}{\&PartialD;u}=\frac{1}{i^{\&prime;}},\frac{\&PartialD;L}{\&PartialD;i^{\&prime;}}=-\frac{u}{i^{\&prime;2}}$

$\begin{array}{c}{\mathrm{\&sigma;}}_L=\sqrt{{\left(\frac{\&PartialD;L}{\&PartialD;u}\right)}^2{\mathrm{\&sigma;}}_u^2+{\left(\frac{\&PartialD;L}{\&PartialD;i^{\&prime;}}\right)}^2{\mathrm{\&sigma;}}_{i^{\&prime;}}^2}\\ =\sqrt{{\left(\frac{1}{i^{\&prime;}}\right)}^2{\mathrm{\&sigma;}}_u^2+{(-\frac{u}{{\left(i^{\&prime;}\right)}^2})}^2{\mathrm{\&sigma;}}_{i^{\&prime;}}^2}\\ \widetilde{=}\frac{1}{i^{\&prime;}}\&CenterDot;\sqrt{{\mathrm{\&sigma;}}_u^2+{\left(\frac{u}{i^{\&prime;}}\right)}^2{\mathrm{\&sigma;}}_{i^{\&prime;}}^2}=\frac{1}{i^{\&prime;}}\&CenterDot;\sqrt{{\mathrm{\&sigma;}}_u^2+2\&CenterDot;{\left(\frac{L}{\mathrm{\&Delta;t}}\right)}^2{\mathrm{\&sigma;}}_i^2},({\mathrm{\&sigma;}}_i={\mathrm{\&sigma;}}_{i_{t+\mathrm{\&Delta;t}}}={\mathrm{\&sigma;}}_{i_t})\end{array}$

When pressing shadow region image data, namely and during the μ F of L>=2, first quadratic sum item of the standard deviation of inductance namely voltage measurement contribution part can be ignored, be then reduced to further:

$\begin{array}{c}{\mathrm{\&sigma;}}_L\&le;2\&CenterDot;\sqrt{{\mathrm{\&sigma;}}_u^2+2\&CenterDot;{\left(\frac{L}{\mathrm{\&Delta;t}}\right)}^2{\mathrm{\&sigma;}}_i^2}\\ =\frac{\sqrt{2{\mathrm{\&sigma;}}_u^2+4\&CenterDot;{\left(\frac{L}{\mathrm{\&Delta;t}}\right)}^2{\mathrm{\&sigma;}}_i^2}}{2\mathrm{\&pi;fI}}=\frac{L{\mathrm{\&sigma;}}_i}{\mathrm{\&pi;fI\&Delta;t}}\end{array}$

Following formula can obtain the standard deviation of inductance by empirical data:

1) make L=0.1 μ F, supposing that Cai Kacai leads is 10M

$\begin{array}{c}{\mathrm{\&sigma;}}_L=\frac{1}{i^{\&prime;}}\&CenterDot;\sqrt{{\mathrm{\&sigma;}}_u^2+2\&CenterDot;{\left(\frac{L}{\mathrm{\&Delta;t}}\right)}^2{\mathrm{\&sigma;}}_i^2}\\ =\frac{\sqrt{2{\mathrm{\&sigma;}}_u^2+4\&CenterDot;{\left(\frac{L}{\mathrm{\&Delta;t}}\right)}^2{\mathrm{\&sigma;}}_i^2}}{2\mathrm{\&pi;fI}}\\ =\frac{\sqrt{2\&times;0.000001+4\&times;{\left(\frac{0.1}{0.1}\right)}^2\&times;0.000001}}{2\&times;3.14\&times;50\&times;2000}=3.9\&times;{10}^{-9}F\end{array}$

${\mathrm{\&theta;}}_L=\frac{{\mathrm{\&sigma;}}_L}{L}=\frac{{3.9\&times;10}^{-9}}{0.1\&times;{10}^{-6}}=3.9\%$

(1) make L=2000 μ F, it is 10M that same hypothesis Cai Kacai leads,

${\mathrm{\&sigma;}}_L=\frac{\sqrt{2\&times;0.000001+4\&times;{\left(\frac{2000}{0.1}\right)}^2\&times;0.000001}}{2\&times;3.14\&times;50\&times;2000}=6.4\&times;{10}^{-2}F$

${\mathrm{\&theta;}}_L=\frac{{\mathrm{\&sigma;}}_L}{L}=\frac{6.4\&times;{10}^{-5}}{2000\&times;{10}^{-6}}=3.2\%.$

5. three-phase alternating current electric inductance measuring-testing instrument as claimed in claim 2, is characterized in that:

The course of work of described Levenberg-Marquardt algorithm is as follows:

Gather voltage signal and the current signal i of a certain branch road, hypothesized model is:

Application Levenberg-Marquardt estimates four parameter: A _u, A _i, and effective value can be drawn like this through software process and the phase place of voltage leading current

There is following system of equations:

Resolve it, can obtain:

From above formula, as long as estimate: A _u, A _i, and just can calculate the intuition L of the inductance to be measured and straight resistance R of inductance to be measured.