CN106249068A - A kind of ferromagnetic element no-load characteristic low frequency measurement method - Google Patents

Abstract

A kind of low frequency measurement method of ferromagnetic element no-load characteristic, mainly comprise the steps: the first step: according to T-shaped equivalent circuit, set up high-pressure side open circuit equivalent circuit, apply, in low-pressure side, the low-frequency sine that 2 frequencies are different, calculate the core loss under each frequency；Second step: the unit magnetic hysteresis of unit of account cycle generation and eddy-current loss W_eAnd W_h, and calculate the core loss P converted to power frequency_Coren；3rd step: calculate the exciting current I converted to power frequency according to eddy current backoff algorithm_exn, harmonic content K_(k), excitation voltage U_n；4th step: calculate open circuit loss P_n；5th step: draw P_Coren‑U_n, I_exn‑U_nRelation curve, and K_(k)‑U_nHarmonic content form.The method uses low-frequency power to replace power frequency supply to carry out test can lower experiment power supply capacity, reduction testing equipment volume and weight at double, makes experimentation cost lower.

Description

A kind of ferromagnetic element no-load characteristic low frequency measurement method

Technical field

The invention belongs to ferromagnetic element no-load characteristic field of measuring technique, mainly comprise open circuit loss, excitation property, zero load Current harmonic content is measured, and is specifically related to the ferromagnetic elements such as transformator, transformer, reactor.

Background technology

The ferromagnetic elements such as transformator, transformer, reactor as power transmission and transforming equipment most important in power system, its performance Quality directly affect the safety of power system, economical operation.The open circuit loss of ferromagnetic element, excitation property and no-load current Harmonic content is the important indicator of reaction ferromagnetic element iron core performance." GB1094.1-2013 power transformer Part I: total Then ", it is desirable to open circuit loss and no-load current are measured as routine test, can lack as the local checked and find in test product magnetic circuit Fall into and general defect.Regulation in " JB/T501-2006 power transformer test directive/guide ": when carrying out no-load test, should be each from test product The rated voltage of high-pressure side winding (generally low pressure winding) the supply rated frequency in winding, remaining winding is opened a way；Transformator No-load current harmonic measure is special test, consists of detection no-load current harmonic wave and numerical value is to check saturated journey unshakable in one's determination Degree, the reasonability of checking design." GB22071.1-2008 transformer test guidance part 1: current transformer " and " GB 22071.2-2008 transformer test guidance part 2: voltage transformer " all specify to need voltage (electric current) transformer is carried out Excitation property is tested." GB 1094.6-2011 power transformer the 6th part: reactor " also specify reactor and must carry out zero load The measurement of loss.But along with the raising of line voltage grade, electric pressure and the capacity of the ferromagnetic elements such as transformator the most gradually increase Greatly, it is the biggest to carry out testing equipment capacity required during no-load test, volume and weight, causes no-load test program multiple Miscellaneous, operator's personal safety can not get ensureing.

Therefore, finding a kind of new energy short form test process, the ferromagnetic element alleviating testing equipment weight and volume is unloaded Characteristic test method is necessary.

Summary of the invention

For the deficiency of above-mentioned existing ferromagnetic element no-load characteristic measuring method, the present invention proposes a kind of employing low frequency Power supply carries out ferromagnetic element no-load test.From E=4.44fN Φ, the saturation voltage unshakable in one's determination of ferromagnetic element is basic with power supply frequently Rate is directly proportional, under the excitation of low-frequency power, it is possible to be substantially reduced supply voltage, and no-load current is basically unchanged, thus can become The capacity of demultiplication small test power supply.Measure open circuit loss, no-load current and the harmonic characterisitic thereof under low frequency, further according to related algorithm Calculate open circuit loss, no-load current and the harmonic content thereof converted to industrial frequency experiment, reach to replace with low-frequency tests The purpose of industrial frequency experiment.Test proves, this method has preferable concordance with directly using industrial frequency experiment method.

In order to achieve the above object, the present invention adopts the following technical scheme that

A kind of low frequency measurement method of ferromagnetic element no-load characteristic, is characterized in that:

1, the equivalent-circuit model of ferromagnetic element high-pressure side open circuit is set up, shown in Fig. 1.Wherein R_dcFor the unidirectional current on winding Resistance, L_σFor this side winding leakage inductance, R_eFor eddy-current loss equivalent resistance, the nonlinear inductance L of band hysteresis ring_mFor magnetizing inductance, magnetic Stagnant loss P_hIt is included in L_mIn.i_exT () is exciting current, i_mT () is for flowing through L_mMagnetizing current, i_eT () is eddy-current loss equivalence Electric current, u (t) is the excitation voltage being applied on winding；

2, ferromagnetic element open circuit loss is mainly core loss, and core loss is mainly by magnetic hystersis loss and eddy-current loss group Become:

$P_{Core}=P_h+P_e=C_h{\mathrm{fB}}_m^{n}V+C_e{\mathrm{\Δ}}^2{f}^2{B}_m^{2}V=W_{h}f+W_e{f}^2---\left(1\right)$

In formula, P_hAnd P_eIt is respectively magnetic hystersis loss and eddy-current loss；C_eFor eddy current loss factor, resistivity determines；C_hFor magnetic Stagnant loss factor, material character determines；B_mFor magnetic flux peak value unshakable in one's determination；F is frequency；V is core volume；Δ is stalloy thickness；W_h And W (W/Hz)_e(W/Hz²) it is respectively unit magnetic hysteresis and eddy-current loss that each cycle of magnetization produces.If therefore ensureing different frequency B under rate_mUnanimously, then it is believed that W_e、W_hFor constant, during test, it is ensured that the U/f under different frequency is consistent, then it is believed that B_m Equal.W can be obtained by the core loss under two different frequencies_hAnd W_eValue；

3, allowing winding high voltage side open a way, low-pressure side applies voltage, records voltage electricity when U/f is equal under two different frequencies Flow data.The computing formula of iron loss:

$P_{Fe}=\frac{1}{T}{\∫}_0^{T}u\left(t\right)\·i_{ex}\left(t\right)dt-{I_{ex}}^2\·R_{dc}---\left(2\right)$

In formula, u (t) is consequently exerted at the voltage at winding two ends, i_exT () is exciting current, I_exIt it is its virtual value；

4, calculate iron loss corresponding under each frequency, obtain:

$\left\{\begin{array}{c}{P}_{Core1}=W_h{f}_1+W_e{f}_1^2\\ P_{Core2}=W_h{f}_2+W_e{f}_2^2\end{array}\right.---\left(3\right);$

5, by formula (3), solve equation and can try to achieve W_eAnd W_hFor:

$\left\{\begin{array}{c}{W}_e=\frac{f_1{P}_{Core2}-f_2{P}_{Core1}}{f_1{f}_2(f_2-f_1)}\\ W_h=\frac{f_2^2{P}_{Core1}-f_1^2{P}_{Core2}}{f_1{f}_2(f_2-f_1)}\end{array}\right.---\left(4\right);$

6, therefore, the iron loss under power frequency is converted:

$P_{Coren}=f_n{W}_h+f_n^2{W}_e---\left(5\right)$

Wherein, f_nFor rated frequency, generally 50Hz or 60Hz；

7, iron loss electric current can be divided into magnetic hystersis loss electric current and eddy loss currents:

$I_{Fe}=I_h+I_e=\frac{P_{Fe}}{E}=\frac{W_{h}f}{E}+\frac{W_e{f}^2}{E}---\left(6\right)$

In formula, I_Fe、I_h、I_eFor the virtual value of corresponding current, by E=K_vfNB_mS, knows that E is directly proportional to frequency f, therefore eddy current Loss current i_eIt is directly proportional to frequency first power, magnetic hystersis loss electric current i_hUnrelated with frequency.And because of B under different frequency_mIt is equal, So i_mEqual, under conversion to power frequency exciting current:

8, because of eddy loss currents i_eIt is directly proportional to frequency first power, the eddy current under conversion to power frequency:

I_en=I_e·f_n/f (7)

9, being known by Fig. 1, eddy current, containing only fundametal compoment, therefore has only to when calculating exciting current mend eddy current In the fundametal compoment to exciting current repaid, phasor diagram is as in figure 2 it is shown, conversion is to the exciting current fundametal compoment under power frequency:

10, the exciting current under power frequency is converted:

$I_{exn}=\sqrt{I_{exn\left(1\right)}^2+\underset{k=2}{\overset{\mathrm{\∞}}{\Σ}}{I}_{ex\left(k\right)}^2}---\left(9\right)$

Wherein, I_ex(k)For kth subharmonic current virtual value under low frequency；

11, no-load current harmonic wave percent:

$K_{\left(k\right)}=\frac{I_{exn\left(k\right)}}{I_{exn}}\×100\%---\left(10\right)$

K_(k)The percent of fundamental current virtual value is accounted for for kth subharmonic current, due to positive and negative half axial symmetry of waveform symmetry, Even harmonic content is substantially zeroed.Therefore k takes 1,3,5,7 ..., during k > 1, low frequency is humorous with the no-load current high order under power frequency excitation Wave amplitude is equal, i.e. I_exn(k)=I_ex(k)；

12, the open circuit loss under rated frequency is converted:

$P_n=P_{Coren}+P_{Cun}=P_{Coren}+I_{exn}^2\·R_{dc}---\left(11\right);$

13, the least due to the pressure drop in leakage inductance during zero load, can ignore, the excitation voltage under conversion to rated frequency:

U_n=E f_n/f+I_exn·R_dc (12)。

The most just the conversion excitation voltage U to power frequency can be obtained_n(power frequency excitation voltage virtual value) and the zero load under power frequency Loss, exciting current and the corresponding relation of no-load current harmonic content thereof, reach to use low-frequency tests to replace industrial frequency experiment Purpose.

Comparing with existing technology, the present invention possesses following advantage:

1. use low-frequency sine power supply to test, can reduction experiment power supply capacity at double, volume and weight, make Test process is convenient, and cost is lower；

2. reduce test voltage, the insulating properties of test equipment are required low, has ensured the safety of testing crew.

Accompanying drawing explanation

In order to make the no-load characteristic measuring method of the ferromagnetic element of the present invention, principle apparent, below in conjunction with accompanying drawing Described in further detail to the present invention, wherein:

The equivalent circuit diagram of a kind of ferromagnetic element high-pressure side open circuit that Fig. 1 provides for the embodiment of the present invention；

The phasor diagram that a kind of ferromagnetic element exciting current that Fig. 2 provides for the embodiment of the present invention compensates；

A kind of ferromagnetic element no-load characteristic low frequency measurement method preferred embodiment principle that Fig. 3 provides for the embodiment of the present invention Figure；

A kind of ferromagnetic element no-load characteristic measuring method schematic diagram that Fig. 4 provides for the embodiment of the present invention；

Fig. 5 measures for employing this method that the embodiment of the present invention provides and the contrast of power frequency actual measurement, and (a) is that open circuit loss is surveyed Amount contrast, (b) is that excitation property measures contrast.

Detailed description of the invention

The embodiment of the present invention provides a kind of low frequency measurement method of ferromagnetic element no-load characteristic, in order to make the art Personnel are better understood from the technical scheme in the present invention, below in conjunction with the drawings and specific embodiments in the embodiment of the present invention Technical scheme carry out clearly, be fully described by, it is clear that described embodiment is only a part of embodiment of the present invention, and It is not all, of embodiment.Based on the embodiment in the present invention, those of ordinary skill in the art are not making creative work The every other embodiment obtained under premise, all should belong to the scope of protection of the invention.

It is as follows that it measures process:

See Fig. 4, for the measuring method schematic diagram of the present invention.

Step 100: according to T-shaped equivalent-circuit model, set up the equivalent circuit opened a way in ferromagnetic element side (high-pressure side), as Shown in Fig. 1, wherein R_dcFor the D.C. resistance on winding, L_σFor this side winding leakage inductance, R_eFor eddy-current loss equivalent resistance, band magnetic hysteresis The nonlinear inductance L of winding_mFor magnetizing inductance, magnetic hystersis loss P_hIt is included in L_mIn.i_exT () is exciting current, i_mT () is for flowing through L_mMagnetizing current, i_eT () is eddy-current loss equivalent current, u (t) is the excitation voltage being applied on winding；

Step 200: the measurement process schematic of the preferred embodiment that the present invention provides is as in figure 2 it is shown, high-pressure side open circuit, low Pressure side applies the low-frequency sine (ensureing that the U/f under different frequency is equal) of 2 frequencies, and data acquisition unit record is the most electric Current voltage data, calculate the core loss under each frequency according to formula (2)；

Step 300: calculate unit magnetic hystersis loss W in each cycle of magnetization according to formula (3)～(4)_hWith eddy-current loss W_e；

Step 400: calculate the core loss P converted to power frequency according to formula (5)_Coren；

Step 500: calculate the eddy current I converted to power frequency according to formula (6)～(8)_e, exciting current fundametal compoment I_exn(1)；

Step 600: calculate the exciting current I converted to power frequency according to formula (9)～(10)_exnAnd harmonic content K_(k)；

Step 700: calculate open circuit loss P converted to power frequency according to formula (11)_n；

Step 800: calculate excitation voltage virtual value U converted to power frequency according to formula (12)_n；

Step 900: draw P_Coren-U_n, I_exn-U_nRelation curve, and K_(k)-U_nHarmonic content form.

The above is only the detailed description of the invention of the present invention, makes to skilled artisans appreciate that or realize this Bright.Multiple amendment to these embodiments will be apparent to one skilled in the art, as defined herein General Principle can realize without departing from the spirit or scope of the present invention in other embodiments.Therefore, the present invention It is not intended to be limited to the embodiments shown herein, and is to fit to and principles disclosed herein and features of novelty phase one The widest scope caused.

Claims (5)

1. the low frequency measurement method of a ferromagnetic element no-load characteristic, it is characterised in that comprise the steps:

Step one: according to T-shaped equivalent circuit, sets up high-pressure side open circuit equivalent circuit, applies different low of 2 frequencies in low-pressure side Frequency sine-wave, calculates the core loss under each frequency；

Step 2: use that interpolation calculation frequency is different, equal E/f time core loss, calculate not under voltage unit period produce Raw unit magnetic hysteresis and eddy-current loss W_eAnd W_h, and calculate the core loss P converted to power frequency_Coren；

Step 3: calculate the exciting current I converted to power frequency according to eddy current backoff algorithm_exn, harmonic content K_(k), excitation Voltage U_n；

Step 4: calculate open circuit loss P according to the iron loss under conversion to power frequency and copper loss_n；

Step 5: draw P_Coren-U_n, I_exn-U_nRelation curve, and K_(k)-U_nHarmonic content form.

2. require the low frequency measurement method of described a kind of ferromagnetic element no-load characteristic according to right 1, it is characterised in that step one institute The U/f that the core loss stated is to ensure that under ferromagnetic element different frequency is equal, to ensure the magnetic flux B under different frequency_mEqual bar Core loss under part.

3. require the low frequency measurement method of described a kind of ferromagnetic element no-load characteristic according to right 1, it is characterised in that described step W described in rapid two_eAnd W_hIt is to obtain according to the core loss linear equation in two unknowns group solving under two frequencies.

4. require the low frequency measurement method of described a kind of ferromagnetic element no-load characteristic according to right 1, it is characterised in that described step Eddy current, because eddy current is containing only fundametal compoment, is only compensated exciting current by the eddy current backoff algorithm described in rapid three In fundametal compoment.

5. require the low frequency measurement method of described a kind of ferromagnetic element no-load characteristic according to right 1, it is characterised in that described step Copper loss described in rapid four is to be updated in Ohm's law be calculated according to the exciting current under conversion to power frequency.