CN104133130A - Transformer direct-current magnetic bias current calculation method and system based on fault recording data - Google Patents

Abstract

The invention discloses a transformer direct-current magnetic bias current calculation method based on fault recording data. The method is characterized by comprising the steps of acquiring a fault recording data signal at the moment of transformer direct-current magnetic bias saturation alarm and forming a recording waveform file, converting the recording waveform file into an ASCII code data file, selecting ASCII code data of transformer neutral point current according to the ASCII code data file, calculating direct current, fundamental current and harmonic current components, acquiring spectrograms of the direct current, the fundamental current and the harmonic current components, and calculating the effective value of current. The invention further discloses a transformer direct-current magnetic bias current calculation system. According to the invention, the direct-current magnetic bias current, the fundamental current, the harmonic currents and the effective-value current can be automatically processed and calculated according to transformer fault recording, and whether the direct-current magnetic bias of a transformer exceeds the withstand direct current capability of equipment can be judged so as to put forward the next control measure and ensure safe and stable operation of main transformer equipment.

Description

Transformer DC magnetic bias current computing method and system based on fault recorder data

Technical field

The invention belongs to the power transmission and transformation field of electric system, relate to high voltage direct current transmission project under the monopolar ground return method of operation, cause computing method and the computing system of neutral point direct current under transformer neutral point DC magnetic biasing operating mode, fundamental current, individual harmonic current and effective value electric current.

Background technology

Along with high voltage direct current transmission project puts into operation more and morely, the addressing of earthing pole, build and put into operation also more and more important.Under the high voltage direct current transmission project monopolar ground return method of operation, earthing pole Injection Current can cause utmost point location the earth around to present electric potential gradient to a certain degree, and centered by utmost point location with concentric circles radial direction toward external radiation.Apart from the transformer of two neutral-point solid grounds in earthing pole certain distance, there is pressure reduction in neutral point current potential, thereby cause DC magnetic bias phenomena.DC magnetic biasing enters overhead transmission line from a transformer neutral point, and from another transformer neutral point backflow the earth.DC magnetic biasing can work the mischief to static exciter, and Hui Cong linear zone, working point unshakable in one's determination enters saturation region, and exciting current sharply increases, and harmonic wave increases, and causes thus the series harm such as transformer leakage field, overheated, noise and vibration.

Literature search is found, at present the research of DC magnetic biasing is focused mostly on and calculated at the Point Drifting scheduling theory of topological structure of electric impact, earthy finite element analysis, fundamental magnetization curve, also do not carry out calculating and the analysis of DC magnetic bias current and harmonic current from production scene fault recorder data angle.

When DC magnetic bias phenomena occurs, transformer can trigger the failure wave-recording of saturated alarm, and transformer neutral point Hall cell sensor can monitor the record waveform data of alternating current-direct current stack.At present, small stream Lip river is crossed right bank power transmission Guangdong DC engineering and has been monitored from western current conversion station the failure wave-recording signal that several times DC magnetic biasing triggers.Record ripple signal often includes abundant information, and unloading, signal conversion and the calculating of record ripple being carried out to data can obtain abundant information, particularly important to device security stable operation.

In addition,, in converter power transformer, each three of YY type converter power transformer and YD type converter power transformer are one group, with a neutral-point solid ground.So in the time analyzing converter power transformer neutral point recorder data, calculate respectively according to converter power transformer YY and YD type.In current document, also the DC magnetic bias current of converter power transformer failure wave-recording is not carried out to computational analysis.

Therefore, the data analysis of the existing DC magnetic bias phenomena for production scene transformer, needs badly and further develops and improve.

Summary of the invention

For above deficiency, one of object of the present invention is to provide this kind of transformer DC magnetic bias current computing method based on fault recorder data, is intended to solve robotization that existing fault recorder data fails to realize and processes the problem of DC magnetic biasing data analysis.

To achieve these goals, the technical scheme that the present invention takes is:

Transformer DC magnetic bias current computing method based on fault recorder data, it comprises the following steps:

Fault recorder data signal while obtaining the saturated alarm of transformer DC magnetic bias, forms record waveform file;

Convert described record waveform file to ASCII character data file;

According to described ASCII character data file, pick out the ASCII character data of transformer neutral point electric current;

Based on discrete Fourier transformation, calculate DC current, fundamental current and individual harmonic current component according to the ASCII character data of described transformer neutral point electric current;

Obtain the spectrogram of DC current, fundamental current and individual harmonic current component according to the result of calculation of described DC current, fundamental current and individual harmonic current component;

Calculate current effective value according to the ASCII character data of described transformer neutral point electric current.

Described transformer comprises YY converter power transformer and YD converter power transformer, and described ASCII character data file comprises the ASCII character data file of YY converter power transformer and the ASCII character data file of YD converter power transformer.

The file layout of described ASCII character data file is Rich Text Format, and file suffixes is called .RTF, the suffix .DAT by name when computing machine calls.

Described fault recorder data signal gathers by Hall cell sensor.

The fault recorder data signal of Hall cell sensor collection is raw data, between described raw data and Hall cell sensor secondary side data value, there is the first no-load voltage ratio, the ratio of described raw data and the first no-load voltage ratio is described secondary data value, between described Hall cell sensor secondary side data value and Hall cell sensor primary side data value, have the second no-load voltage ratio, the product of described secondary data value and the second no-load voltage ratio is described Hall cell sensor primary side data value.

Described based on discrete Fourier transformation, the method for calculating DC current, fundamental current and individual harmonic current component according to the ASCII character data of described transformer neutral point electric current comprises the following steps:

Step 1, Fourier transform formula based on continuous function

$F\left(\mathrm{\ω}\right)=\underset{-\∞}{\overset{+\∞}{\∫}}f\left(t\right)\·e^{-\mathrm{j\ωt}}\mathrm{dt}---\left(1\right)$

Obtaining its inverse Fourier transform formula is

$f\left(t\right)=\frac{1}{2\mathrm{\π}}\underset{-\∞}{\overset{+\∞}{\∫}}F\left(\mathrm{\ω}\right)e^{\mathrm{j\ωt}}\mathrm{d\ω}---\left(2\right)$

Wherein ω is angular frequency, and ω=2 π f, and f is frequency;

Step 2, formula (1) is rewritten into the discrete Fourier transformation formula of finite length sequence:

$X\left(k\right)=\mathrm{DFT}\left[x\left(n\right)\right]=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)e^{-j\frac{2\mathrm{\π}}{N}\mathrm{nk}}---\left(3\right)$

Calculate DC current, fundamental current and individual harmonic current component, in formula (3), N is the sampling length of discrete signal, k is the signal number of times of frequency domain, X (k) is k component of degree n n in frequency domain, wherein, what k=0 interval scale calculated is 0 component of degree n n in frequency domain, i.e. DC current; What k=1 interval scale calculated is 1 component of degree n n in frequency domain, i.e. fundamental current; K=2,3,4 ... interval scale individual harmonic current component; X (n) is the transformer neutral point current value of n sampled point in sampling length N, 0≤n≤N-1.

The computing method of described current effective value are:

The effective value of serial-pulse, its computing formula is formula (4):

$I_{\mathrm{rms}}=\sqrt{\frac{1}{T}\underset{0}{\overset{T}{\∫}}{i}^2\left(t\right)\·\mathrm{dt}}---\left(4\right)$

In formula (4), I _rmsfor current effective value, T is the cycle, and i (t) is the momentary current value in t moment,

And in record waveform file, data are all by the discrete point acquisition of sampling, so the discrete form of formula (4) can be write the form of an accepted way of doing sth (5):

$I_{\mathrm{rms}}=\sqrt{\frac{1}{T}\underset{0}{\overset{T}{\∫}}{i}^2\left(m\right)}---\left(5\right)$

In formula (5), i (m) is the transformer neutral point current value in m moment in cycle T.

Another object of the present invention is to provide this kind of transformer DC magnetic bias current computing system based on fault recorder data, be intended to solve robotization that existing fault recorder data fails to realize and process the problem of DC magnetic biasing data analysis.

To achieve these goals, the technical scheme that the present invention takes is:

A transformer DC magnetic bias current computing system based on fault recorder data, it comprises:

The unit of data acquisition, the fault recorder data signal when obtaining the saturated alarm of transformer DC magnetic bias, forms record waveform file;

Date Conversion Unit, for converting described record waveform file to ASCII character data file;

Data selection unit, for according to described ASCII character data file, picks out the ASCII character data of transformer neutral point electric current;

The first computing unit, for based on discrete Fourier transformation, calculates DC current, fundamental current and individual harmonic current component according to the ASCII character data of described transformer neutral point electric current;

Spectrogram generation unit, for obtaining the spectrogram of DC current, fundamental current and individual harmonic current component according to the result of calculation of described DC current, fundamental current and individual harmonic current component;

The second computing unit, for calculating current effective value according to the ASCII character data of described transformer neutral point electric current.

Described spectrogram generation unit obtains the spectrogram of DC current, fundamental current and individual harmonic current component by Origin instrument.

Described fault recorder data signal is from any in Hall cell sensor, voltage transformer (VT) or current transformer.

The present invention is based on fault recorder data, and utilize computer programming, adopt the mathematical methods such as discrete Fourier transformation, failure wave-recording signal is carried out to data conversion storage and signal conversion, data are calculated.The present invention can record ripple according to transformer fault, automatically processes record ripple signal and calculates DC magnetic bias current, fundamental current, individual harmonic current and effective value electric current.The present invention can make operational management personnel whether exceed equipment tolerance direct current ability to transformer DC magnetic bias to judge, and proposes next step management and control measure, has greatly alleviated operational management personnel's workload, ensures transformer main equipment safe and stable operation.

Brief description of the drawings

Fig. 1 is YY and YD converter power transformer neutral point failure wave-recording under DC magnetic biasing operating mode provided by the invention.

Fig. 2 is the YY converter power transformer neutral point record ripple ASCII character data based on Origin instrument provided by the invention.

Fig. 3 is the YD converter power transformer neutral point record ripple ASCII character data based on Origin instrument provided by the invention.

Fig. 4 is YY converter power transformer neutral point failure wave-recording harmonic current result of calculation provided by the invention.

Fig. 5 is YD converter power transformer neutral point failure wave-recording harmonic current result of calculation provided by the invention.

Fig. 6 is computing system process flow diagram provided by the invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, content of the present invention is described in further details.

Embodiment

Please refer to shown in Fig. 6, a kind of transformer DC magnetic bias current computing method based on fault recorder data, it comprises the following steps:

One, obtain primary fault recorder data.Please refer to shown in Fig. 1.Fig. 1 is the failure wave-recording signal that converter power transformer automatically triggers in the time of the saturated alarm of DC magnetic biasing, be respectively YY (primary side secondary side is Y-connection) type and YD (primary side is Y-connection, and secondary side is that triangle connects) type converter power transformer neutral point record ripple.Fault recorder data signal can be from Hall cell sensor, also can be from AC current transformer or voltage transformer (VT).And for the fault recorder data signal of DC magnetic biasing technical Analysis, from Hall cell sensor.Between the raw data (raw data) of the failure wave-recording that Hall cell sensor obtains and secondary side data value (secondary data), no-load voltage ratio is defined as ratio, and raw data is obtained Hall cell sensor secondary terminals data value divided by ratio.Between Hall cell sensor secondary side data value (secondary data) and primary side data value (primary data), there is the second no-load voltage ratio (utilizing Hall effect is secondary side Weak current signal by large primary side current transformation).Secondary side data value is multiplied by the second no-load voltage ratio and is primary side data value.

Two, failure wave-recording signal is preserved into record waveform file, and save as ASCII character data file, the form of ASCII character data file is Rich Text Format (RTF), file suffixes is called .RTF, the formatted file of suffix RTF by name, can use the operating system board tool to open such as Windows XP/7, the suffix .DAT by name when these data of Fortran routine call.Failure wave-recording waveform after unloading is mapped as shown in Figures 2 and 3 with Origin instrument.Wherein, Fig. 2 is YY type converter power transformer fault recorder data, and Fig. 3 is YD type converter power transformer fault recorder data.

Three, utilize Fortran language, write the computer program based on discrete Fourier transformation, the rich text format data file of routine call YY and YD converter power transformer.

The computer program that calculates DC current, fundamental current and harmonic current based on discrete Fourier transformation, it comprises following calculation procedure:

Fourier transform (FT) formula of step 1, continuous function is

$F\left(\mathrm{\ω}\right)=\underset{-\∞}{\overset{+\∞}{\∫}}f\left(t\right)\·e^{-\mathrm{j\ωt}}\mathrm{dt}---\left(6\right)$

Wherein ω is angular frequency, and ω=2 π f, and f is frequency.

Its inverse Fourier transform (IFT) formula is

$f\left(t\right)=\frac{1}{2\mathrm{\π}}\underset{-\∞}{\overset{+\∞}{\∫}}F\left(\mathrm{\ω}\right)e^{\mathrm{j\ωt}}\mathrm{d\ω}---\left(7\right)$

Step (2). the formula in step 1 (6) is rewritten into discrete Fourier transformation (DFT) formula of finite length sequence, formula is

$X\left(k\right)=\mathrm{DFT}\left[x\left(n\right)\right]=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)e^{-j\frac{2\mathrm{\π}}{N}\mathrm{nk}}---\left(8\right)$

Wherein, the length that N is discrete signal samples, the signal number of times that k is frequency domain, what k=0 interval scale calculated is 0 component of degree n n in frequency domain, i.e. DC current, what k=1 interval scale calculated is 1 component of degree n n in frequency domain, i.e. fundamental current.Its inverse discrete Fourier transform (IDFT) formula is

$x\left(n\right)=\mathrm{IDFT}\left[X\left(k\right)\right]=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}X\left(k\right)e^{j\frac{2\mathrm{\π}}{N}\mathrm{nk}}---\left(9\right)$

Step 3, on the basis of formula (8) substitution sampling length N, write Fortran program and calculate DC current (k=0), fundamental current (k=1) and individual harmonic current (k=2,3,4 ...).Program calculated result is as shown in the table.

Table 1 converter power transformer neutral point failure wave-recording DFT transformation calculations result

Write the computer program based on Fortran language, calculate current effective value, the rich text format data file of routine call YY and YD converter power transformer.

The computer program of described calculating current effective value, it comprises following calculation procedure:

The effective value (root-mean-square value) of step 1, serial-pulse, its computing formula is formula (10).

$I_{\mathrm{rms}}=\sqrt{\frac{1}{T}\underset{0}{\overset{T}{\∫}}{i}^2\left(t\right)\·\mathrm{dt}}---\left(10\right)$

In formula (10), I _rmsfor current effective value, T is the cycle, and i is instantaneous value.And in recorder data file, data are all by the discrete point acquisition of sampling.So the discrete form of formula (10) can be write the form of an accepted way of doing sth (11).

$I_{\mathrm{rms}}=\sqrt{\frac{1}{T}\underset{0}{\overset{T}{\∫}}{i}^2\left(m\right)}---\left(11\right)$

In formula (11), i (m) is m moment wave-recording sampling data value.Current effective value result of calculation is as shown in table 2.

Table 2 converter power transformer neutral point failure wave-recording current effective value result of calculation

Four, utilize Origin instrument to make the spectrogram of the individual harmonic current calculating in step 3.As shown in Figure 4, YY converter power transformer neutral point failure wave-recording harmonic current as shown in Figure 5 for YY converter power transformer neutral point failure wave-recording harmonic current.

At present, the DC magnetic biasing technical Analysis of successful implementation of the present invention in Xi Luodu right bank power transmission Guangdong engineering ± 500kV from western current conversion station converter power transformer.Advantage of the present invention is, by converter power transformer neutral point failure wave-recording file, recorded wave file is transformed to ASCII character data and transfers the rich text format file that computer program can be identified to.By computer program, the present invention can calculate under the monopolar ground return method of operation automatically, the DC magnetic bias current of AC transformer or converter power transformer solid earthed neutral, fundamental current, individual harmonic current and effective value electric current.The present invention builds a kind of DC magnetic biasing calculated signals and analytic system based on recorder data, the result of calculation of native system can solve the signal analysis problem of transformer DC magnetic bias, and provides data basis for hazard evaluations such as transformer core under Under Direct Current Bias is saturated, leakage field, harmonic wave increases.Equipment-patrolling, the equipment control that is applied as operations staff in station of the present invention provides strong technical support.

Finally explanation is, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although the present invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can modify or be equal to replacement technical scheme of the present invention, and not departing from aim and the scope of technical solution of the present invention, it all should be encompassed in the middle of claim scope of the present invention.

Claims (10)

1. the transformer DC magnetic bias current computing method based on fault recorder data, is characterized in that, it comprises the following steps:

Fault recorder data signal while obtaining the saturated alarm of transformer DC magnetic bias, forms record waveform file;

Convert described record waveform file to ASCII character data file;

According to described ASCII character data file, pick out the ASCII character data of transformer neutral point electric current;

Based on discrete Fourier transformation, calculate DC current, fundamental current and individual harmonic current component according to the ASCII character data of described transformer neutral point electric current;

Obtain the spectrogram of DC current, fundamental current and individual harmonic current component according to the result of calculation of described DC current, fundamental current and individual harmonic current component;

Calculate current effective value according to the ASCII character data of described transformer neutral point electric current.

2. the transformer DC magnetic bias current computing method based on fault recorder data according to claim 1, it is characterized in that, described transformer comprises YY converter power transformer and YD converter power transformer, and described ASCII character data file comprises the ASCII character data file of YY converter power transformer and the ASCII character data file of YD converter power transformer.

3. the transformer DC magnetic bias current computing method based on fault recorder data according to claim 1, it is characterized in that, the file layout of described ASCII character data file is Rich Text Format, and file suffixes is called .RTF, the suffix .DAT by name when computing machine calls.

4. the transformer DC magnetic bias current computing method based on fault recorder data according to claim 1, is characterized in that, described fault recorder data signal gathers by Hall cell sensor.

5. the transformer DC magnetic bias current computing method based on fault recorder data according to claim 4, it is characterized in that, the fault recorder data signal of Hall cell sensor collection is raw data, between described raw data and Hall cell sensor secondary side data value, there is the first no-load voltage ratio, the ratio of described raw data and the first no-load voltage ratio is described secondary data value, between described Hall cell sensor secondary side data value and Hall cell sensor primary side data value, there is the second no-load voltage ratio, the product of described secondary data value and the second no-load voltage ratio is described Hall cell sensor primary side data value.

6. the transformer DC magnetic bias current computing method based on fault recorder data according to claim 1, it is characterized in that, described based on discrete Fourier transformation, the method for calculating DC current, fundamental current and individual harmonic current component according to the ASCII character data of described transformer neutral point electric current comprises the following steps:

Step 1, Fourier transform formula based on continuous function

$F\left(\mathrm{\ω}\right)=\underset{-\∞}{\overset{+\∞}{\∫}}f\left(t\right)\·e^{-\mathrm{j\ωt}}\mathrm{dt}---\left(1\right)$

Obtaining its inverse Fourier transform formula is

$f\left(t\right)=\frac{1}{2\mathrm{\π}}\underset{-\∞}{\overset{+\∞}{\∫}}F\left(\mathrm{\ω}\right)e^{\mathrm{j\ωt}}\mathrm{d\ω}---\left(2\right)$

Wherein ω is angular frequency, and ω=2 π f, and f is frequency;

Step 2, formula (1) is rewritten into the discrete Fourier transformation formula of finite length sequence:

$X\left(k\right)=\mathrm{DFT}\left[x\left(n\right)\right]=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)e^{-j\frac{2\mathrm{\π}}{N}\mathrm{nk}}---\left(3\right)$

Calculate DC current, fundamental current and individual harmonic current component, in formula (3), N is the sampling length of discrete signal, k is the signal number of times of frequency domain, X (k) is k component of degree n n in frequency domain, wherein, what k=0 interval scale calculated is 0 component of degree n n in frequency domain, i.e. DC current; What k=1 interval scale calculated is 1 component of degree n n in frequency domain, i.e. fundamental current; K=2,3,4 ... interval scale individual harmonic current component; X (n) is the transformer neutral point current value of n sampled point in sampling length N, 0≤n≤N-1.

7. the transformer DC magnetic bias current computing method based on fault recorder data according to claim 1, is characterized in that, the computing method of described current effective value are:

The effective value of serial-pulse, its computing formula is formula (4):

$I_{\mathrm{rms}}=\sqrt{\frac{1}{T}\underset{0}{\overset{T}{\∫}}{i}^2\left(t\right)\·\mathrm{dt}}---\left(4\right)$

In formula (4), I _rmsfor current effective value, T is the cycle, and i (t) is the momentary current value in t moment,

And in record waveform file, data are all by the discrete point acquisition of sampling, so the discrete form of formula (4) can be write the form of an accepted way of doing sth (5):

$I_{\mathrm{rms}}=\sqrt{\frac{1}{T}\underset{0}{\overset{T}{\∫}}{i}^2\left(m\right)}---\left(5\right)$

In formula (5), i (m) is the transformer neutral point current value in m moment in cycle T.

8. the transformer DC magnetic bias current computing system based on fault recorder data, is characterized in that, it comprises:

The unit of data acquisition, the fault recorder data signal when obtaining the saturated alarm of transformer DC magnetic bias, forms record waveform file;

Date Conversion Unit, for converting described record waveform file to ASCII character data file;

Data selection unit, for according to described ASCII character data file, picks out the ASCII character data of transformer neutral point electric current;

The first computing unit, for based on discrete Fourier transformation, calculates DC current, fundamental current and individual harmonic current component according to the ASCII character data of described transformer neutral point electric current;

Spectrogram generation unit, for obtaining the spectrogram of DC current, fundamental current and individual harmonic current component according to the result of calculation of described DC current, fundamental current and individual harmonic current component;

The second computing unit, for calculating current effective value according to the ASCII character data of described transformer neutral point electric current.

9. the transformer DC magnetic bias current computing system based on fault recorder data according to claim 8, is characterized in that, described spectrogram generation unit obtains the spectrogram of DC current, fundamental current and individual harmonic current component by Origin instrument.

10. the transformer DC magnetic bias current computing system based on fault recorder data according to claim 8, is characterized in that, described fault recorder data signal is from any in Hall cell sensor, voltage transformer (VT) or current transformer.