CN102854389A - Transformer winding deformation testing device - Google Patents

Abstract

The invention relates to a transformer winding deformation testing device which comprises a microprocessor and a signal collecting unit, wherein the microprocessor and the signal collecting unit are in bi-directional connection with a data bus, and the signal collecting unit is further connected with a signal processing unit. The data bus is in output connection with a sine wave frequency conversion circuit and a phase switching unit, the sine wave frequency conversion circuit is in output connection with the phase switching unit, and the phase switching unit is connected with the signal processing unit through a load. The transformer winding deformation testing device is further provided with an alternating current (AC) voltage input unit, an electro-magnetic interference (EMI) filtering rectification unit, a power factor correction (PFC) unit and an inverter circuit which are all in sequential input connection. The transformer winding deformation testing device can accurately calculate an inductive reactance value and a resistance value of the transformer under power frequency, the inductive reactance value and the resistance value can be compared with a nameplate value of the transformer, faults can be found timely before occurring in the transformer, the fault rate and running risks of the transformer are remarkably reduced, manual workload in detection is also greatly reduced simultaneously, and safety in running of the transformer is effectively guaranteed.

Description

The deformation of transformer winding proving installation

Technical field

The present invention relates to the proving installation of transformer, is the deformation of transformer winding proving installation concretely.

Background technology

At present the fault detect of transformer there is following several method usually:

Impedance method: the winding deformation method of testing of using the earliest is impedance method.Its principle is by impedance or the leakage reactance of measuring transformer winding under 50Hz, judges by the variation of impedance or leakage reactance value whether Transformer Winding the distortion of operation has occured to jeopardize, such as turn-to-turn short circuit, open circuit, coil displacements etc.GB and IEC standard (IEC) have all been stipulated the limit value that leakage reactance changes under the rated current, and it be unusually that the IEC suggestion surpasses 3%, and GB is thought and got 2%～4% according to the difference of loop construction.96 years versions of U.S.'s ansi standard are tested short-circuit impedance as one of prerun project.

And on-the-spot use experience for many years shows, owing to limit by condition, impedance method is difficult to reach rated current (especially for high-power transformer), and the accuracy of detection to test instrumentation requires very high, often be difficult to obtain necessary detection sensitivity, sometimes only effective to the serious transformer of those winding deformations.

Impulse method: the end in Transformer Winding adds standard impulse voltage signal (100V) over the ground, utilize digitized record equipment to measure simultaneously voltage-to-ground signal Vo (t) and the Vi (t) at winding two ends, and process accordingly, finally obtain transport function h (t) or the H (j ω) of this Transformer Winding, that is:

h(t)=Vo(t)/Vi(t)

h(jω)=Vo(jω)/Vi(jω)

Then judge deformation of transformer winding according to wave form varies.

Method of frequency response method: the end input sweep voltage signal Vs(of winding inputs the sine voltage signal of different frequency successively), detect simultaneously voltage-to-ground signal Vi (n) and the Vo (n) at winding two ends under the different scanning frequency by digitized record equipment, and process accordingly, finally obtain the transfer function H (n) of tested Transformer Winding:

H(n)=20log[Vo(n)/Vi(n)]

And depict frequency response as curve according to frequency and judge deformation of transformer winding.

The frequency sweep impedance method: the frequency sweep impedance method is a kind of novel winding deformation research method, can comprehensive diagnostic winding characteristic, and can take into account the measurement of power frequency impedance value, see related standards and technical conditions requirement that whether it meets product, and the reason that load loss and short-circuit impedance do not meet standard-required analyzed, find out the defective of transformer device structure and manufacturing.

Because all the time, adopt at the scene power frequency supply as experiment power supply, test out load loss and the short-circuit impedance value of transformer.Although can be as the foundation of judging, along with the growth of electricity needs and changeable operating mode, to monitoring and the detection of main apparatus transformer, the requirement of prevention main equipment accident is more and more higher.This not only wants and can accurately detect after accident transformer, and it is particularly important that the criterion of the science of making that the deteriorated and accident of expecting for transformer simultaneously is possible shows.In the simultaneously test of the low pressure impedance method under power frequency, because the contrast of single resistance value, and the humorous wave interference of power frequency supply, make test value and actual value that certain deviation be arranged, this has brought with regard to the judgement that is in critical value for some can not expected result.This is so that there is following defective in traditional method of testing:

(1) under the traditional test pattern, can not effectively carry out the electric test of standardization.

Resistance value under the tradition power frequency is single, inadequate to judging the winding characteristic.Although the testing impedance under the frequency sweep of Criterion can reduce human error by carrying out standardized test, avoid test to leak item, the standardization test job can't effectively be carried out under the traditional test pattern.Also need after test report is finished manually test data, test report input computer, PMS system to be preserved, increase labor capacity and wrong probability, reduce testing efficiency.

(2) under the traditional test pattern, the data analysis degree of depth is low.

Under the traditional test pattern, the tester mainly is confined to on-the-spot test, and data depth analysis, inquiry, vertical or horizontal comparison are lacked condition, therefore it is often more shallow to reach a conclusion according to field test data, depth analysis need to be got back to teams and groups and just can carry out, often put into operation if any unusual, the tested device that exceeds standard but find data this moment, can not have a power failure retests again.

(3) under the traditional test pattern, the later stage work amounts such as test data processing are large.

Under the traditional test pattern, tester's field test data has just been finished the sub-fraction of work, get back to need to calculate after the teams and groups, the contrast test data, provide test report, artificial calculated amount is very large.

Summary of the invention

For above-mentioned problem, the invention provides a kind of deformation of transformer winding proving installation, before breaking down, transformer in time finds fault, and point out, reduce failure rate and the operation risk of transformer, significantly reduce simultaneously the labor workload that detects, the safe operation of effective guarantee transformer.

Deformation of transformer winding proving installation of the present invention includes and the two-way microprocessor that is connected of data bus and signal gathering unit, and wherein signal gathering unit also is connected with signal processing unit;

Data bus output is connected with sinusoidal wave frequency changer circuit and Phase-switching unit, and output connects described sinusoidal wave frequency changer circuit to the Phase-switching unit, and the Phase-switching unit is connected with described signal processing unit by load transformer;

Also have AC voltage input block, EMI(electromagnetic interference (EMI) that order input connects) filter rectification unit, PFC(power factor correction) unit and inverter circuit, inverter circuit connects described sinusoidal wave frequency changer circuit output.

Traditional testing tool can only carry out testing impedance or the frequency test of transformer, and main limited reason is the restriction of testing power supply, and common impedance instrument uses civil power as testing power supply, does not possess the function of frequency conversion; Common frequency response tester can conversion frequency but voltage be generally below the 12V, do not possess load-carrying ability, can accurately not provide resistance value.Therefore sinusoidal wave frequency changer circuit is the core of apparatus of the present invention.Sinusoidal wave frequency changer circuit has the functions such as frequency modulation, pressure regulation, current limliting, protection.Adopt the Natural Sampling ratio juris to calculate the intersection point of sinusoidal modulation wave and triangular carrier, obtain corresponding pulsewidth and inter-train pause time, generate SPWM(sinusoidal pulse width modulation signal), make the not wide rectangular pulse train of sinusoidal wave frequency changer circuit output and a series of constant amplitudes of sinusoidal wave equivalence, frequency and the amplitude of regulating inverter output voltage by changing modulation wave frequency and amplitude.Proving installation as judging reference, can in time find that distortion appears in transformer with test data, in order to before accident, just can find and point out to go wrong, and resistance value and the frequency characteristic of all right disposable test Three-Phase Transformer of while proving installation.

Further, also has the holding circuit that input connects to the data bus in the proving installation, with the state indication unit that is connected with holding circuit.Wherein can comprise overvoltage crowbar, current foldback circuit, short-circuit protection circuit and temperature protection circuit etc.After holding circuit notes abnormalities, can report to the police by sound or display device, guard mode can manually read by microprocessor.

Concrete, in described sinusoidal wave frequency changer circuit, the signal output pin of control integration piece connects the control pin of the first breakover element, ground connection after another pin of the first breakover element is connected with current-limiting resistance by the first transformation element, the first transformation element also is connected to peripheral circuit with first inductance of connecting, the second inductance and the 3rd inductance.Wherein said the first breakover element can be field effect transistor, also can have for other element of similar conducting function, such as triode etc.

Make the PFC unit improve the power factor of variable-frequency power sources by the control integration piece, the AC voltage of input extends to AC90V to the AC260V universe, the output peak point current of control integration piece is 1A, thereby can make the rapid charge and discharge of grid capacitance of the first breakover element of field effect transistor form.The first transformation element utilizes Current Mutual Inductance to take a sample from the first breakover element, therefore on average current sensing control method, has improved the overall efficiency of proving installation.The PWM(pulse-width signal) part mainly realizes jointly by the first transformation element, current-limiting resistance, the first breakover element.In sinusoidal wave frequency changer circuit, also by single-ended converter and slope-compensation, realized the accurate control of dutycycle.Amplitude oscillator and electric current input multiplier have strengthened noise immunity.Slope equalizer is able to programme, and it is out of control that over-voltage comparator can be avoided when load disconnects.The first inductance, the second inductance and the 3rd inductance power storage release energy when voltage is near 0 when voltage is near peak value.

Concrete, in described inverter circuit, have a PWM control module and the 2nd PWM control module, wherein a PWM control module links to each other with the conducting pin of the 3rd breakover element by the control pin of the second breakover element, and the 2nd PWM control module links to each other with the conducting pin of the 5th breakover element by the control pin of the 4th breakover element;

Be coupled with the second transformation element and the 3rd transformation element between the second breakover element and the 3rd breakover element and the 4th breakover element and the 5th breakover element, input end of the 3rd transformation element connect and the control pin and conducting pin of the second breakover element between;

Secondary and the 3rd transformation element of the second transformation element secondary is connected with respectively two groups of commutation diodes.

Wherein preferred, described the second breakover element, the 3rd breakover element, the 4th breakover element and the 5th breakover element are field effect transistor, also can have for other element of similar conducting function, such as triode etc.

The second breakover element of the pwm signal controlling filed effect form of tubes of the one PWM control module and the 2nd PWM control module, the 3rd breakover element, the 4th breakover element, the 5th breakover element alternation switch control voltage are coupled to secondary again by the second transformation element and the 3rd transformation element, realize inversion by secondary commutation diode again.In inverter circuit, also has current control mode pulse width modulator.So-called current control mode pulse width modulator comes adjusting pulsewidth according to connecing feedback current.Input end at pwm comparator directly compares with the signal and the error amplifier output signal that flow through the outputting inductance coil, thereby the adjusting dutycycle makes the inductance peak point current tracking error change in voltage of output and changes.Owing on the structure Voltage loop and electric current loop bicyclic system are arranged, therefore voltage regulation factor, load regulation and the transient response characteristic of Switching Power Supply all are significantly increased, and are present more satisfactory new controller.

Preferably, in signal gathering unit, be provided with 2～5 data acquisition channels and two buffer units.Adopt the FPGA(field programmable gate array) control technology, realize the data acquisition of two high-speed, high precision acquisition channels, the high sampling rate 500Ksps of every passage.Two buffer units can make acquisition system be in the acquisition state always, guarantee the continuity of data.In the process of frequency sweep, that signal has is sudden, dynamic range is large, can't pre-set appropriate measurement range.For the signal of great dynamic range, adopt five road parallel acquisition techniques, respectively 40dB, 60dB, 80dB and four kinds of linear amplifying signals of 100dB and 0～100dB logarithmic detector signal are carried out parallel sampling.

Test is learnt, deformation of transformer winding proving installation of the present invention, and the frequency of test can be at 10Hz～2kHz, and power is 3000VA, for Measurement accuracy provides good basis.Can calculate accurately transformer impedance value, induction reactance value under the power frequency, can compare with the transformer name plate rating, and can before breaking down, transformer in time find fault, failure rate and the operation risk of transformer have significantly been reduced, also significantly reduce simultaneously the labor workload that detects, effectively ensured the safe operation of transformer.

Below in conjunction with the embodiment of embodiment, foregoing of the present invention is described in further detail again.But this should be interpreted as that the scope of the above-mentioned theme of the present invention only limits to following example.Do not breaking away from the above-mentioned technological thought situation of the present invention, various replacements or change according to ordinary skill knowledge and customary means are made all should comprise within the scope of the invention.

Description of drawings

Fig. 1 is the structured flowchart of deformation of transformer winding proving installation of the present invention.

Fig. 2 is the partial circuit figure of sinusoidal wave frequency changer circuit among Fig. 1.

Fig. 3 is the partial circuit figure of inverter circuit among Fig. 1.

Embodiment

The deformation of transformer winding proving installation includes and the two-way microprocessor that is connected of data bus and signal gathering unit as shown in Figure 1, and wherein signal gathering unit also is connected with signal processing unit;

Data bus output is connected with sinusoidal wave frequency changer circuit and Phase-switching unit, and output connects described sinusoidal wave frequency changer circuit to the Phase-switching unit, and the Phase-switching unit is connected with described signal processing unit by load transformer.

The AC voltage input block, EMI filter rectification unit, PFC unit and the inverter circuit that also have the AC90V～AC260V of order input connection, inverter circuit connects described sinusoidal wave frequency changer circuit output.Calculate the intersection point of sinusoidal modulation wave and triangular carrier by sinusoidal wave frequency changer circuit, obtain corresponding pulsewidth and inter-train pause time, generate SPWM(sinusoidal pulse width modulation signal), make the not wide rectangular pulse train of sinusoidal wave frequency changer circuit output and a series of constant amplitudes of sinusoidal wave equivalence, frequency and the amplitude of regulating inverter output voltage by changing modulation wave frequency and amplitude.

Also has the holding circuit that input connects to the data bus, with the state indication unit that is connected with holding circuit.Described holding circuit comprises overvoltage crowbar, current foldback circuit, short-circuit protection circuit and temperature protection circuit.

In the sinusoidal wave frequency changer circuit as shown in Figure 2, the signal output pin of control integration piece U2 connects the control pin of the first breakover element Q2, ground connection after another pin of the first breakover element Q2 of field-effect tube structure is connected with current-limiting resistance R21 by the first transformation elements T 1, the first transformation elements T 1 also is connected to peripheral circuit with first inductance L 3 of connecting, the second inductance L 4 and the 3rd inductance L 5.

Control integration piece U2 by the ML4812 model makes the PFC unit improve the power factor of variable-frequency power sources, the AC voltage of input extends to AC90V to the AC260V universe, the output peak point current of control integration piece U2 is 1A, thereby can make the rapid charge and discharge of grid capacitance of the first breakover element Q2 of the field effect transistor form of 24N60C3 model.The first transformation elements T 1 utilizes Current Mutual Inductance to take a sample from the first breakover element Q2, therefore on average current sensing control method, has improved the overall efficiency of proving installation.The PWM(pulse-width signal) part mainly realizes jointly by the first transformation elements T 1, current-limiting resistance R21, the first breakover element Q2.In sinusoidal wave frequency changer circuit, also by single-ended converter and slope-compensation, realized the accurate control of dutycycle.Amplitude oscillator and electric current input multiplier have strengthened noise immunity.Slope equalizer is able to programme, and it is out of control that over-voltage comparator can be avoided when load disconnects.The first inductance L 3, the second inductance L 4 and the 3rd inductance L 5 power storages release energy when voltage is near 0 when voltage is near peak value.

In described inverter circuit, a PWM control module U7 and the 2nd PWM control module U8 with SG3525 model, wherein a PWM control module U7 links to each other with the conducting pin of the 3rd breakover element Q4 by the control pin of the second breakover element Q3, and the 2nd PWM control module U8 links to each other with the conducting pin of the 5th breakover element Q6 by the control pin of the 4th breakover element Q5;

The input end that is coupled with the second transformation elements T 2 and the 3rd transformation elements T 3, the three transformation elements T 3 between the second breakover element Q3 and the 3rd breakover element Q4 and the 4th breakover element Q5 and the 5th breakover element Q6 connect and the control pin and conducting pin of the second breakover element Q3 between; Wherein the second breakover element Q3, the 3rd breakover element Q4, the 4th breakover element Q5 and the 5th breakover element Q6 are field-effect tube structure.Secondary and the 3rd transformation elements T 3 of the second transformation elements T 2 secondary is connected with respectively two groups of commutation diodes.

In inverter circuit, also has current control mode pulse width modulator.So-called current control mode pulse width modulator comes adjusting pulsewidth according to connecing feedback current.Input end at pwm comparator directly compares with the signal and the error amplifier output signal that flow through the outputting inductance coil, thereby the adjusting dutycycle makes the inductance peak point current tracking error change in voltage of output and changes.Owing on the structure Voltage loop and electric current loop bicyclic system are arranged, therefore voltage regulation factor, load regulation and the transient response characteristic of Switching Power Supply all are significantly increased, and are present more satisfactory new controller.

In signal gathering unit, adopt the FPGA(field programmable gate array) control technology, acquisition channel by two high-speed, high precisions gathers data, a voltage measurement passage, a current measurement passage, the input range of voltage measurement passage are 0～400V, and the input range of current channel is 0～20A, the high sampling rate of every passage is 500ksps, and each acquisition channel quantified precision is 16.Adopt simultaneously the Sampling techniques of negative delay, circulation, two buffer memorys, signal gathering unit is in the acquisition state always, bicirculating buffer memory design has guaranteed the continuity of data.

In the process of frequency sweep, that signal has is sudden, dynamic range is large, can't pre-set appropriate measurement range; For the signal of great dynamic range, adopt five road parallel acquisition techniques, respectively 40dB, 60dB, 80dB and four kinds of linear amplifying signals of 100dB and 0～100dB logarithmic detector signal are carried out parallel sampling.What do like this is a little: signals collecting will realize the dynamic range of 100dB, namely 100,000/ precision, adopt merely high-resolution AD device to be difficult to realize, also can involve great expense even realize.Therefore adopt simultaneously Sampling techniques of four-way, namely simultaneously 40dB, 60dB, 80dB and 100dB gain passage are gathered, if measured signal less (namely not surpassing high-gain passage maximum range), then will be take signal that this passage was gathered as valid data, otherwise will think that measured signal is larger, automatically take signal that another low-gain channel was gathered as valid data.The advantage of this mode is not need to set in advance range, is adapted in wide dynamic range, and the waveform of sudden signal is carried out high precision collecting.Adopt the 16bit analog to digital converter, acquisition precision is accomplished 13bit, and the measuring accuracy in each range is 1/ (2^13), is enough to guarantee the measuring accuracy more than 0.1% in each range.

In the software control of test macro, adopt relevant relative method: namely adopt first lateral comparison approach, choose the winding of same model, structure, material and electric pressure and test, relatively load loss and the short-circuit impedance value under same frequency.By the longitudinal comparison method, the load loss that test gathers and short-circuit impedance compare with history or factory data again.Then by amplitude-frequency response collection of illustrative plates horizontal, the longitudinal comparison short-circuit impedance, checking is in 10Hz～2kHz data test precision.At last by the FFT(fast fourier transform) technique computes goes out short-circuit impedance and frequency function collection of illustrative plates Zke=H(f) relation, demonstrate the amplitude-frequency response characteristic curve by display screen.F=10Hz～2kHz scope value.Utilize the scope of facies relationship numerical value to judge laterally, the result of longitudinal comparison, to judge the degradation of Transformer Winding.

In digital signal processing, usually need to use discrete Fourier transform (DFT) (DFT), to obtain the frequency domain character of signal.Although traditional DFT algorithm can obtain the signal frequency domain feature, the algorithm calculated amount is large, and length consuming time is unfavorable for that computing machine processes signal in real time.Therefore since being found to DFT, within very long a period of time, all can not be applied in the actual engineering project, until a kind of fast discrete Fourier computing method (FFT) are found.So that discrete Fourier transform (DFT) just is used widely in the engineering of reality.It is emphasized that FFT is not a kind of new frequency domain character obtain manner, but a kind of quick implementation algorithm of DFT.The computing formula of DFT:

$\left(\begin{array}{cc}X\left(k\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)W_N^{\mathrm{nk}}& (k=\mathrm{0,1}...N-1)\\ W_N=e^{-j\frac{2\mathrm{\π}}{N}}& \end{array}\right)---\left(1\right)$

Wherein x (n) represents the discrete digital burst of input, W _NBe twiddle factor, X (k) is the relative amplitude of the frequency content of N Frequency point composition.Generally speaking, suppose that x (n) comes from low pass sampling, sample frequency is fs, and X (k) has represented that frequency interval is fs/N from-fs/2 leads so, to fs/2-fs/N by the relative amplitude of N Frequency point.Because only being actually on frequency axis from the one-tenth cycle, one group of discrete frequency amplitude that DFT calculates changes, i.e. X (k+N)=X (k).Therefore get arbitrarily the calculating effect that N point all can represent DFT.The negative frequency comparison of ingredients is abstract, beyonds one's depth, and according to the cyclophysis of X (k), so we can think that again X (k) has represented from zero frequency, frequency interval is fs/N, to fs-fs/N by the relative amplitude of N Frequency point.

The DFT computing formula that provides according to (1) formula, can know that a Frequency point X of every calculating (k) all needs to carry out N complex multiplication and N-1 complex addition, the X (k) that calculates the N each point needs the inferior complex addition of N^2 complex multiplication and N * (N-1) altogether.When x (n) is in the situation of real number, calculate 2 * N^2 time real multiplications of DFT needs that N order, the inferior real addition of 2 * N * (N-1).

Twiddle factor W _NHave following character:

1.W _NSymmetry

${\left(W_N^{\mathrm{nk}}\right)}^{*}=W_N^{-\mathrm{nk}}---\left(2\right)$

2.W _NPeriodicity

$W_N^{\mathrm{nk}}=W_N^{(n+N)k}=W_N^{n(k+N)}---\left(3\right)$

3.W _NReducibility

$W_N^{\mathrm{nk}}=W_{\mathrm{mN}}^{\mathrm{mnk}},$ $W_N^{\mathrm{nk}}=W_{N/m}^{\mathrm{nk}/m}---\left(4\right)$

According to above these character, can obtain formula (5):

$W_N^{n(N-k)}=W_N^{(N-n)k}=W_N^{-\mathrm{nk}},$ $W_N^{N/2}=-1,W_N^{(k+N/2)}=-W_N^k---\left(5\right)$

Supposing that sample sequence is counted is that N=2^L, L are integer, can not add artificially several and 0 satisfies this requirement so that sample sequence is counted if do not satisfy this condition.At first we with sequence x (n) according to odd even be divided into two groups as follows:

$\left.\begin{array}{c}x\left(2r\right)=x_1\left(r\right)\\ x(2r+1)=x_2\left(r\right)\end{array}\right\},$ $r=\mathrm{0,1}...\frac{N}{2}-1$ (6)

So have according to DFT computing formula (1):

So far, the DFT that we order a N transforms the form for formula (7), and this moment, the value of k was 0 to N-1.Be divided into now two sections and discuss, when k is 0～N/2-1, because x1 (r), the sequence that x2 (r) is ordered for N/2, so formula (7) can be written as:

$X\left(k\right)=X_1\left(k\right)+W_N^k{X}_2\left(k\right)k=0...N/2-1---\left(8\right)$

And when the k value was N/2～N-1, k replaced with k'+N/2, and the k' value is 0～N/2-1.Can get formula (7) abbreviation:

$X\left(k\right)=\underset{r=0}{\overset{N/2-1}{\mathrm{\Σ}}}{x}_1\left(r\right)W_{N/2}^{r(k^{\′}+N/2)}+W_N^{k^{\′}+N/2}\underset{r=0}{\overset{N/2-1}{\mathrm{\Σ}}}{x}_2\left(r\right)W_{N/2}^{r(k^{\′}+N/2)}$

$=\underset{r=0}{\overset{N/2-1}{\mathrm{\Σ}}}{x}_1\left(r\right)W_{N/2}^{r{k}^{\′}}-W_N^{k^{\′}}\underset{r=0}{\overset{N/2-1}{\mathrm{\Σ}}}{x}_2\left(r\right)W_{N/2}^{r{k}^{\′}}$

$=X_1\left(k^{\′}\right)-W_N^{k^{\′}}{X}_2\left(k^{\′}\right)k^{\′}=0...N/2-1---\left(9\right)$

Comprehensive above derivation can obtain as drawing a conclusion: the DFT conversion process that N is ordered can represent with the DFT conversion process that two N/2 are ordered, and its concrete formula is suc as formula the iterative formula of DFT fast algorithm shown in (10):

$X_N\left(k\right)=\left\{\begin{array}{cc}{X}_{N/2}^{\′}\left(k^{\′}\right)+W_N^k{X}_{N/2}^{\′\′}\left(k^{\′\′}\right)& k=0...N/2-1\\ X_{N/2}^{\′}\left(k^{\′}\right)-W_N^k{X}_{N/2}^{\′\′}\left(k^{\′\′}\right)& k=N/2...N-1\end{array}\right.---\left(10\right)$

X'(k' in the following formula) being the discrete Fourier transform (DFT) of even item branch, X''(k'') is the discrete Fourier transform (DFT) of odd term branch.

The test frequency of deformation of transformer winding proving installation of the present invention can be at 10Hz～2kHz, and power is 3000VA, for Measurement accuracy provides good basis.Can calculate accurately transformer impedance value, induction reactance value under the power frequency, can compare with the transformer name plate rating, and can before breaking down, transformer in time find fault, failure rate and the operation risk of transformer have significantly been reduced, also significantly reduce simultaneously the labor workload that detects, effectively ensured the safe operation of transformer.

Claims (8)

1. deformation of transformer winding proving installation is characterized by:

Include and the two-way microprocessor that is connected of data bus and signal gathering unit, wherein signal gathering unit also is connected with signal processing unit;

Data bus output is connected with sinusoidal wave frequency changer circuit and Phase-switching unit, and output connects described sinusoidal wave frequency changer circuit to the Phase-switching unit, and the Phase-switching unit is connected with described signal processing unit by load transformer;

Also have AC voltage input block, EMI filter rectification unit, PFC unit and inverter circuit that the order input connects, inverter circuit connects described sinusoidal wave frequency changer circuit output.

2. deformation of transformer winding proving installation as claimed in claim 1 is characterized by: also have the holding circuit that input connects to the data bus, with the state indication unit that is connected with holding circuit.

3. deformation of transformer winding proving installation as claimed in claim 2, it is characterized by: described holding circuit comprises overvoltage crowbar, current foldback circuit, short-circuit protection circuit and temperature protection circuit.

4. such as the described deformation of transformer winding proving installation of one of claims 1 to 3, it is characterized by: in described sinusoidal wave frequency changer circuit, the signal output pin of control integration piece (U2) connects the control pin of the first breakover element (Q2), ground connection after another pin of the first breakover element (Q2) is connected with current-limiting resistance (R21) by the first transformation element (T1), the first transformation element (T1) also is connected to peripheral circuit with first inductance (L3) of connecting, the second inductance (L4) and the 3rd inductance (L5).

5. deformation of transformer winding proving installation as claimed in claim 4 is characterized by: described the first breakover element (Q2) is field effect transistor.

6. such as the described deformation of transformer winding proving installation of one of claims 1 to 3, it is characterized by: in described inverter circuit, have a PWM control module (U7) and the 2nd PWM control module (U8), wherein a PWM control module (U7) links to each other with the conducting pin of the 3rd breakover element (Q4) by the control pin of the second breakover element (Q3), and the 2nd PWM control module (U8) links to each other with the conducting pin of the 5th breakover element (Q6) by the control pin of the 4th breakover element (Q5);

Be coupled with the second transformation element (T2) and the 3rd transformation element (T3) between the second breakover element (Q3) and the 3rd breakover element (Q4) and the 4th breakover element (Q5) and the 5th breakover element (Q6), input end of the 3rd transformation element (T3) connect and the control pin and conducting pin of the second breakover element (Q3) between;

Secondary and the 3rd transformation element (T3) of the second transformation element (T2) secondary is connected with respectively two groups of commutation diodes.

7. deformation of transformer winding proving installation as claimed in claim 6, it is characterized by: described the second breakover element (Q3), the 3rd breakover element (Q4), the 4th breakover element (Q5) and the 5th breakover element (Q6) are field effect transistor.

8. such as the described deformation of transformer winding proving installation of one of claims 1 to 3, it is characterized by: in signal gathering unit, be provided with 2～5 data acquisition channels and two buffer units.

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