CN104698417B - A kind of analog input formula flicker tester discriminating method - Google Patents
A kind of analog input formula flicker tester discriminating method Download PDFInfo
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Abstract
The invention discloses a kind of analog input formula flicker tester discriminating method, belongs to power system flickering signal testing field, and specific steps have：First, analog input formula flicker tester is tested using the standard measuring signals of IEC61000 4 15, tentatively judges whether analog input formula flicker tester meets the design requirement of the flicker test standards of IEC61000 4 15；2nd, tectonic remnant basin flickering signal, respectively the first signal, secondary signal and the 3rd signal；3rd, analog input formula flicker tester is tested using the level flickering signal constructed, determines whether it is designed in strict accordance with the flicker test standards of IEC61000 4 15.The present invention can screen the analog input formula flicker tester or electric energy quality monitor of each manufacturer's design（Function containing flicker measurement）Whether strictly meet the design requirement of the flickering standards of IEC61000 4 15 and obtain corresponding measuring accuracy.
Description
Technical Field
The invention relates to the field of flicker signal testing in a power system, in particular to a method for discriminating an analog input flicker tester.
Background
Aiming at the problem of voltage flicker caused by voltage amplitude fluctuation in the current power system, the detection and evaluation basis is IEC61000-4-15 standard [1] The International Electrotechnical Commission (International Electrotechnical Commission) is abbreviated as IEC. Flicker detection under the IEC61000-4-15 flicker standard needs a series of processes, such as squaring, filtering, statistics, etc., the design of the actual digital flicker meter is more complex, and the designed hardware cost is also higher. In order to reduce the research and development cost of the flicker tester, some hardware manufacturers do not strictly design according to the flicker design requirement of the IEC61000-4-15 standard, and arbitrarily simplify the flicker detection flow of the flicker tester, aiming at blindly pursuing the flicker detection effect with low cost, high efficiency and rapidity; related hardware performance of some manufacturers is unqualified, and the measurement accuracy requirement of IEC61000-4-15 flicker standard cannot be met. Although the simplified flicker detection method can reduce the hardware cost of the flicker tester and has a good detection effect on certain specific voltage flicker signals, the detection method has design defects in universality and adaptability of flicker signal detection, and the detection result may deviate from an actual flicker value seriously, so that the evaluation of flicker is seriously wrong. Typical flicker reduction design schemes of various manufacturers at present comprise an envelope decomposition method, an average value statistical method and the like.
The flicker signal envelope decomposition method is a method based on Discrete Fourier Transform (DFT) spectrum analysis [2] By sampling the signal sequence u [ n ] for voltage flicker]Calculating the effective value of the full wave or the effective value of the half wave, thereby extracting the envelope curve of the flicker signal and forming a discrete voltage flicker root mean square value sequence U N . To U N Dividing N sections of signals, and performing DFT decomposition on each section of signals to obtain a discrete frequency spectrum array U i (k) I =1, 2, \ 8230, N, and converting the amplitude at the corresponding frequency in each spectrum to the instantaneous flicker value P at that frequency inst (k) Finally, P corresponding to each frequency inst (k) The instantaneous flicker value P of the signal is obtained by summation inst (i) For P of N segments inst (i) Carrying out statistical analysis to obtain a short-time flicker value P st . The envelope decomposition method can obtain the flicker measurement result only by DFT decomposition and instantaneous flicker statistics, greatly simplifies the flicker detection process in the IEC61000-4-15 standard, has higher detection precision for partial voltage flicker signals, and reduces the hardware design cost. However, it has two inevitable problems: firstly, DFT is only suitable for steady-state signals, the phenomenon of frequency spectrum leakage exists for flicker signals with large voltage amplitude fluctuation, and the error of decomposition is too large to be suitable; secondly, the frequency spectrum leakage and the fence effect cannot be eliminated, the decomposition result is influenced, and errors are caused.
The flicker signal average value statistical method is a simple approximation method adopted by some flicker detection instruments in the process of counting instantaneous flicker values, and the instantaneous flicker value P is obtained through a series of filtering links according to IEC61000-4-15 standard inst After (n), the instantaneous flicker sequence is not graded according to the requirements of IEC61000-4-15 standard, the Probability Density Function (PDF) is calculated, the Cumulative Distribution Function (CDF) is calculated, and the short-time flicker value P is calculated by statistics st Equal flow, directly and simply and approximately calculating the total average instantaneous flicker valueThen substituting into formula to obtain short-time flickerThe average value statistical method simplifies the processes of flicker grading, statistics and the like in the IEC61000-4-15 standard, can approximately obtain flicker measurement results when the voltage flicker signal waveform is relatively stable, has certain precision, and also reduces part of the cost of the flicker tester. Although the statistical method of the mean value of the flicker signal is in the instantaneous stateThe flicker grading and counting aspects are simplified, the instantaneous flicker mean value replaces the grading and counting process in IEC61000-4-15 flicker standard, when the voltage waveform is stable and unchanged, the flicker measuring precision is higher, but the actual voltage flicker signal fluctuates at any time, especially when the voltage amplitude fluctuates greatly, the flicker measuring result of the flicker mean value counting method has larger deviation, and further the flicker evaluation is wrong.
Reference to the literature
[1]International Electrotechnical Commission(IEC)Standard 61000-4-15，Electromagnetic Compatibility(EMC)-Part 4：Testing and measurement techniques-Section 15：Flickermeter－Functional and Design Specifications，2010.
[2] Study of a calculation method of a flicker value of Zhao gang, shi Bao, lin Hai Xue [ J ] power grid technology, 2001, 25 (11): 15-18.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for discriminating an analog input type flicker tester, which discriminates the analog input type flicker tester or an electric energy quality monitor (comprising a flicker measurement function) designed by the existing manufacturer, judges whether the analog input type flicker tester or the electric energy quality monitor meets the design requirements of IEC61000-4-15 flicker standards, and can also obtain the measurement precision of the analog input type flicker tester.
In order to solve the technical problems, the invention deeply researches the mechanism of each detection process in the IEC61000-4-15 flicker standard and deduces the calculation formula of flicker signals in the IEC61000-4-15 standard, and provides a hierarchical flicker signal detection method on the basis, which comprises three layers of flicker test signals forming the method, and the specific scheme is as follows:
an analog input type flicker tester screening method comprises the following steps:
testing the analog input type flicker tester by adopting the IEC61000-4-15 standard test signal, and preliminarily judging whether the analog input type flicker tester meets the design requirements of the IEC61000-4-15 flicker test standard, namely according to the IEC61000-4-15 standard, the error isWhether the content is within the range of +/-5 percent; specifically, the flicker signal u of IEC61000-4-15 is generated according to the flicker standard of IEC61000-4-15 AM (t)＝A[1+m f cos(Ω f t+θ f )]cos ω t, where A and ω represent the amplitude and angular frequency of the power frequency carrier voltage, m f 、Ω f And theta f Respectively representing amplitude coefficient, angular frequency and phase of amplitude modulated wave voltage, determining initial phase as 0 and duration as 10min to obtain short-time flicker theoretical value P st ＝0.7139×4K f R f ·100d f In which K is f 、R f And d f The visual sensitivity coefficient, the form factor and the fluctuation size of the fluctuation frequency are respectively;
constructing a level flicker signal which is a first signal, a second signal and a third signal respectively; the first signal is used for judging whether the analog input type flicker tester is strictly designed according to IEC61000-4-15 flicker test standards, the second signal is used for judging whether the analog input type flicker tester is designed based on an average value statistical method, and the third signal is used for judging whether the analog input type flicker tester is designed based on a signal envelope decomposition method; the concrete structure is as follows:
the first signal: setting a flicker test signal u with a sudden change of the fluctuation size of 10min in length f1 (t) the size of the fluctuation is represented by d at the 70 th s f Mutation to 0.25d f When the phase is suddenly changed to be equal to the initial phase, thenA. Omega respectively represents the amplitude and angular frequency of the power frequency carrier voltage, d f 、Ω f Respectively representing the fluctuation size and angular frequency of amplitude modulated wave voltage;
a second signal: setting a flicker test signal u with a sudden change of the fluctuation size of 10min in length f2 (t) the size of the fluctuation of which is at the time t b When is driven by d f Mutation to a.d f In the formula a<1，60s<t b &300s, when the phase is suddenly changed, the phase is equal to the initial phase,
the third signal: flicker test signal u with alternating fluctuation f3 (t) containing a flicker signal of 0.5Hz sine amplitude modulation wave, circulating the flicker signal in a group at a time interval of 15s, wherein the fluctuation value of the first 5s is 2.34 percent of the sine amplitude modulation wave of 0.5Hz, the fluctuation value of the last 10s is reduced to 1/4 of the first 5s, circulating for 40 times in total and lasting for 10min, and the phase when the fluctuation value is changed is equal to the initial phase,wherein n =0, 1, \8230, 39;
the constructed hierarchical flicker signal is adopted to test the analog input type flicker tester, and whether the analog input type flicker tester is strictly designed according to IEC61000-4-15 flicker test standards or not is further judged, namely whether the error is in a range of +/-5% or not is judged according to the IEC61000-4-15 standards or whether the analog input type flicker tester is designed based on an average statistical method or not, namely whether the error between a flicker test value and a theoretical value based on the average statistical method is in a range of +/-5% or whether the analog input type flicker tester is designed based on a signal envelope decomposition method or not, namely whether the error between the flicker test value and the theoretical value based on the signal envelope decomposition method is in a range of +/-5%.
The invention has the beneficial effects that: whether the analog input type flicker tester or the electric energy quality monitor (with flicker measurement function) designed by each manufacturer strictly meets the design requirements of IEC61000-4-15 flicker standard or whether the design is based on an average value statistical method or whether the design is based on a signal envelope decomposition method or not can be discriminated, and corresponding test precision is obtained.
Drawings
The invention is described in further detail below with reference to the following figures and detailed description, wherein:
FIG. 1 is a schematic diagram of the detection process of IEC61000-4-15 flicker standard.
FIG. 2 is a schematic diagram of the hierarchical statistical process of IEC61000-4-15 flicker criteria.
FIG. 3 is a flow chart of a method for detecting a level flicker signal.
FIG. 4 is a graph of the instantaneous flicker profile of Signal A under the IEC61000-4-15 standard flicker tester.
FIG. 5 is a graph of the instantaneous flicker profile of Signal B under the IEC61000-4-15 standard flicker tester.
FIG. 6 is a graph of the instantaneous flicker profile of signal C under the IEC61000-4-15 standard flicker tester.
FIG. 7 is a graph of the instantaneous flicker profile of Signal D under the IEC61000-4-15 standard flicker tester.
FIG. 8 is a graph of the instantaneous flicker profile of signal E under the IEC61000-4-15 standard flicker tester.
FIG. 9 is a graph of the instantaneous flicker profile of signal F under the IEC61000-4-15 standard flicker tester.
Fig. 10 is a graph of the instantaneous flicker profile of signal D in an envelope decomposition flicker tester.
FIG. 11 is a graph of the instantaneous flicker profile of signal E in an envelope decomposition flicker tester.
Fig. 12 is a graph of the instantaneous flicker profile of signal F under an envelope decomposition flicker tester.
Detailed Description
In order to discriminate whether the flicker tester designed by each manufacturer can meet the measurement precision of IEC61000-4-15 flicker standard, detect dynamic signals, design according to the IEC61000-4-15 standard and the like, a hierarchical flicker signal is provided, flicker detection is respectively carried out on each designed layer of flicker signals by the flicker tester to be detected, and the type of the flicker tester, the detection precision of the measuring instrument and the detection capability of the dynamic flicker signal are identified according to the detection result.
In order to construct a level flicker test signal, the invention deduces a flicker detection mechanism based on the IEC61000-4-15 standard.
Flicker detection standard IEC61000-4-15 is an amplitude modulated wave flicker model based on incandescent lamps, and the flicker detection process is shown in FIG. 1, in which FIG. 1 shows voltage flickerInput signal is U AM (t) the output voltage signal of block 3 is u B3 (t) the output voltage signal of block 4 is u B4 (t)，K e For instantaneous flicker gain factor, P inst (t) is the instantaneous flicker value, and the output of block 5 is the short-time flicker measurement P st . The IEC61000-4-15 flicker signal general expression based on the single amplitude modulated wave flicker model is as follows:
u AM (t)＝A[1+m f cos(Ω f t+θ f )]cosωt (1)
wherein A and omega respectively represent amplitude and angular frequency of power frequency carrier voltage, and m f 、Ω f And theta f Respectively representing the amplitude coefficient, angular frequency and phase of the amplitude modulated wave voltage relative to the carrier voltage.
After the flicker signal in the formula (1) passes through the square demodulator of the frame 2 and the band-pass filter of 0.05Hz to 35Hz of the frame 3, the direct current component and the frequency component related to 2 times of power frequency are filtered. Due to m f 1, neglecting m f And (3) squaring the correlation quantity, demodulating amplitude modulated wave components causing flicker, and outputting:
u B3-1 (t)＝m f A 2 cos(Ω f t+θ f ) (2)
in frame 3, the signal u passes through a 0.05-35 Hz band-pass filter B3-1 And (t) carrying out 8.8Hz weighted filtering, wherein the physical meaning is that the sine amplitude-modulated wave voltage with the frequency f is converted into 8.8Hz sine amplitude-modulated wave voltage with equivalent flicker value. If the amplitude modulation wave is other wave, it also needs to multiply the wave factor R of corresponding frequency f f . The signals coming out of block 3 are:
u B3 (t)＝A 2 K f R f m f cos(Ω f t+θ f ) (3)
wherein K f 、R f Respectively, the apparent sensitivity coefficient and the form factor of amplitude modulated wave frequency f. The sine wave corresponds to a waveform factor R f =1, visual sensitivity coefficient K of other waveform f And the form factor R f Can be found in the literature [1 ]]And (6) checking.
Block 3 output signal u B3 (t) multiplication by 1/A 2 The amplitude normalization processing is carried out, and the output signal after passing through the squarer of the frame 4 mainly comprises two parts: a direct current component and a harmonic component. The direct current component contains effective value information of equivalent 8.8Hz sine amplitude modulation wave related to flicker evaluation, and the expression is as follows:
the first-order smoothing filter in box 4 mainly functions to extract the dc component u in equation (4) B4 (t), however, due to the amplitude-frequency characteristics of the filter, the harmonic components cannot be eliminated, and only a corresponding attenuation is performed, and actually the signal output from block 4 has a certain degree of fluctuation. The ideal output signal of this time frame 4 is approximately equal to u B4 (t) if converted to transient flicker P inst (t) further multiplying by a gain factor K e According to IEC61000-4-15 standard, K can be obtained from a unit flicker caused by a sinusoidal amplitude modulation wave having a frequency of 8.8Hz and a voltage fluctuation value of 0.25% e ＝1.28×10 6 Instantaneous flicker P inst The theoretical calculation expression of (t) is:
P inst (t)＝(4K f R f ·100d f ) 2 ＝(8K f R f ·100m f ) 2 (5)
the design flow of the flicker tester in the IEC61000-4-15 standard is formed by the frame 1 to the frame 4, the detection principle of the flicker tester in the IEC61000-4-15 standard is derived mathematically, and the instantaneous flicker P in the amplitude modulated wave flicker model is obtained inst The theoretical formula of (t) provides mathematical basis and theoretical guidance for the design and calibration of the flicker instrument of actual manufacturers.
Instantaneous flicker P given in the foregoing inst (t) evaluating and quantifying the severity of the power system flicker over a period of time by statistical processing of the instantaneous flicker values. The hierarchical and statistical flow chart specified by the IEC61000-4-15 standard is shown in FIG. 2.
According to the instantaneous flicker value obtained in the formula (5) within the measurement time of 10minThe flicker severity degree is further improved and evaluated through smoothing treatment, short-time flicker is calculated according to a statistical formula provided by IEC61000-4-15 standard, and the short-time flicker severity degree (P) is 10min st )：
In the formula P 1s ＝(P 0.7 +P 1 +P 1.5 )/3，P 3s ＝(P 2.2 +P 3 +P 4 )/3，P 10s ＝(P 6 +P 8 +P 10 +P 13 +P 17 )/5，P 50s ＝(P 30 +P 50 +P 80 ) 3, performing the following steps; wherein P is 0.7 Represents the corresponding instantaneous flicker value, P, for the cumulative distribution function CDF =0.7% 1s The corresponding instantaneous flicker value when the cumulative distribution function CDF =1% and after smoothing is represented, and so on.
For steady voltage fluctuation with constant amplitude-modulated wave, instantaneous flicker P inst (t) is theoretically a constant value, a short-time flicker theoretical value P st Comprises the following steps: p is st ＝0.7139×4K f R f ·100d f (7)
The equation (7) shows that the short-time flicker caused by a single amplitude modulation wave is in direct proportion to the fluctuation value thereof P st ∝d 2 。
The frames 1 to 5 form an IEC61000-4-15 standard flicker detection and evaluation flow, the statistical judgment condition when the actual flicker signal fluctuates continuously is considered, and the IEC61000-4-15 standard detection flow should be followed when the actual flicker tester is designed.
Through derivation and knowledge of a flicker detection mechanism of the IEC61000-4-15 standard, the invention constructs a hierarchical flicker signal which is used for discriminating whether an analog input flicker tester or an electric energy quality monitor (comprising a flicker measurement function) designed by various manufacturers strictly meets the design requirements of the IEC61000-4-15 flicker standard. Short-time flicker P under IEC61000-4-15 flicker standard derived by formula (7) st The theoretical calculation formula of (2) is a level flicker signal in the inventionThe reference flicker value calculation of the detection method provides a theoretical basis.
Fig. 3 is a schematic flow chart of a method for detecting a hierarchical flicker signal, and shows that the detection process of the present invention mainly includes firstly testing a flicker tester of an individual manufacturer by using IEC61000-4-15 standard flicker signals, and then testing by using the hierarchical flicker signal constructed by the present invention, where the three hierarchical flicker signals are a first signal, a second signal, and a third signal.
1) IEC61000-4-15 standard test signals: generating a flicker signal with constant single-frequency fluctuation size in an equation (1) according to IEC61000-4-15 flicker standard, wherein the initial phase is 0, the duration is 10min, and the fluctuation amplitude and the fluctuation frequency can be determined according to the literature [1 ]]And (5) designing. The short-time flicker theoretical value P is obtained by the formula (5) and the formula (6) st ：
P st ＝0.7139×4K f R f ·100d f (8)
Wherein K is f 、R f And d f Respectively, the apparent sensitivity coefficient, the form factor and the fluctuation size of the fluctuation frequency. At the moment, the test result of the flicker instrument to be tested is in accordance with the theoretical value calculated by the formula (8), and the error range is within +/-5% of the standard requirement of IEC 61000-4-15. The IEC61000-4-15 standard test signal can detect the measurement precision of the flicker instrument to be measured, and judge whether the measurement precision meets the IEC61000-4-15 flicker standard measurement precision requirement.
2) Flicker test first signal: setting a single-frequency fluctuation sudden-change flicker test signal according to the formula (9), lasting for 10min, wherein the fluctuation value is represented by d when the fluctuation value is 70s f Mutation to 0.25d f The phase at the time of the abrupt change is equal to the initial phase 0.
In the formula, A and omega respectively represent the amplitude and angular frequency of power frequency carrier voltage, d f 、Ω f Respectively showing the fluctuation size and angular frequency of amplitude modulated wave voltage. According to the formula (5), the instantaneous flicker value within 0-70 s is obtainedK f The apparent sensitivity coefficient is corresponding to the amplitude modulation wave frequency f; the instantaneous flash value is within 70 s-10 minObtaining the short-time flicker theoretical value of the flicker test first signal according to the formula (6) as follows:
the first signal of the flicker test can detect whether the flicker tester to be tested is strictly designed according to the IEC61000-4-15 flicker standard, if the measuring result and the calculation result of the formula (10) are within the error range of +/-5 percent, the flicker tester to be tested meets the requirements of the IEC61000-4-15 flicker standard; otherwise, the flash memory is not designed according to IEC61000-4-15 flash standard.
3) Flicker test second signal: setting a flicker test signal with single frequency fluctuation mutation according to the formula (11), wherein the flicker test signal lasts for 10min totally, and the fluctuation size is at the moment t b From d f Mutation to a.d f The phase at the time of the abrupt change is equal to the initial phase 0.
In the formula a<1，60s<t b &And lt, 300s. At this time, 0 to t b Internal instantaneous flicker value oft b Instantaneous flicker value within-10 min ofThe short-time flicker theoretical value of the flicker test second signal is as follows:
the second signal of the flicker test can discriminate whether the flicker tester to be tested is designed based on a flicker mean value statistical method, and the detection result is about:
the test result of the flicker tester designed according to the flicker average value statistical method is smaller and even reaches more than-40 percent.
4) Flicker test third signal: setting a flicker test signal with alternating fluctuation according to a formula (14), wherein the flicker test signal comprises a flicker signal of a 0.5Hz sine amplitude modulation wave, the flicker signal is cyclically changed by taking 15s time intervals as a group, the fluctuation value of the first 5s is 2.34% (corresponding to the 0.5Hz sine amplitude modulation wave), and the fluctuation value of the last 10s is reduced to 1/4 of the fluctuation value of the first 10 s; the total cycle lasts for 10min for 40 times, and the phase of the fluctuation value is equal to the initial phase 0.
Wherein n =0, 1, \ 8230;, 39.
Short-time flicker theoretical value P of flicker test third signal st And =0.6779, whether the flicker tester to be tested is designed based on a signal envelope decomposition method can be discriminated. The flicker measurement result of the flicker tester designed based on the signal envelope decomposition method is larger and can reach more than + 40%.
The above are the constitution mode and the flicker theoretical value of each layer of flicker signal in the method for detecting the level flicker signal, wherein the IEC61000-4-15 standard test signal can detect whether the flicker instrument to be detected preliminarily meets the measurement precision requirement of the IEC61000-4-15 flicker standard; the first signal of the flicker test can discriminate whether the flicker tester to be tested is strictly designed according to IEC61000-4-15 flicker standard; the second signal of the flicker test can identify a flicker tester based on an average statistical method, and the test result of the flicker tester based on the average statistical method is smaller than a theoretical value; the third signal of the flicker test can identify a flicker tester based on a signal envelope decomposition method, and the test result of the flicker tester based on the signal envelope decomposition method is larger than a theoretical value.
By adopting the technical scheme of the invention, corresponding hierarchical signals are designed, the detection results of the flicker tester based on average value statistics and the flicker tester based on the signal envelope decomposition method are respectively compared with the detection results of the flicker tester based on the IEC61000-4-15 flicker standard, and the effectiveness of the hierarchical flicker signal detection method in the aspects of detecting the detection precision, the design principle, the dynamic flicker detection capability and the like of the flicker tester is verified. The detailed test results are as follows:
(1) Designing flicker signals with sudden change of fluctuation size
Signal A: constant fluctuation signals, 8.8Hz sine amplitude modulation waves, the fluctuation size is 0.25%, and the constant fluctuation is maintained for 10 min; short time flicker theoretical value P st ＝0.7139。
Signal B: the fluctuation sudden change signal is a sine amplitude modulation wave of 8.8Hz, the fluctuation value of the signal in the first 55% time period is 0.25%, and the fluctuation value of the signal in the later 45% time period is reduced to 1/4 of the fluctuation value; short-time flicker theoretical value P st ＝0.6961。
Signal C: the fluctuation sudden change signal is a sine amplitude modulation wave of 8.8Hz, the fluctuation value of the signal in the first 20 percent of time period is 0.25 percent, and the fluctuation value of the signal in the later 80 percent of time period is reduced to 1/4 of the fluctuation value in the former time period; short time flicker theoretical value P st ＝0.6592。
Instantaneous flicker P derived under these three different signals inst The (t) distribution is shown in fig. 4, 5 and 6.
The results of the measurements of the flicker meter designed according to the IEC61000-4-15 flicker standard and the mean value statistical method for different flicker signals are shown in Table 1:
TABLE 1 detection results of the flicker testers under different flicker signals
As can be seen from the table 1, the flicker tester designed strictly according to the IEC61000-4-15 flicker standard can complete flicker detection under various conditions, has small detection error, accords with a theoretical value, and can detect a flicker signal with sudden fluctuation amplitude change; the flicker tester based on the average value statistical method has higher flicker detection precision only when the signal fluctuation amplitude is constant (signal A), and the average value statistical method averages all instantaneous flicker values all the time, so that the result is smaller. Therefore, the level signal can screen the flicker tester based on average value statistics and detect the measurement precision of the flicker tester.
(2) Dynamic flicker signal with alternating design fluctuation values
Signal D: a fluctuation stabilization signal of 0.5Hz sine amplitude modulation wave with the fluctuation size of 2.34 percent, the duration of 10min and the short-time flicker theoretical value P st ＝0.7139。
Signal E: the fluctuation amplitude mutation signal is a 0.5Hz sine amplitude modulation wave, the fluctuation value of the signal in the first 1/3 time period is 2.34 percent, and the fluctuation value of the signal in the second 2/3 time period is reduced to the first 1/4; short-time flicker theoretical value P st ＝0.6779。
A signal F: the fluctuation amplitude value alternating change signal, 0.5Hz sine amplitude modulation wave and flicker signal are circulated by taking 15s time interval as a group, the fluctuation amplitude value of the first 5s is 2.34%, and the fluctuation value of the last 10s is reduced to 1/4 of the fluctuation value of the first 5 s; short-time flicker theoretical value P st ＝0.6779。
Instantaneous flicker P derived under these three different signals inst The (t) distribution is shown in fig. 7 to 12.
The measurement results of different flicker signals respectively adopting IEC61000-4-15 standard flicker testers and envelope decomposition method flicker testers are shown in Table 2.
TABLE 2 detection results of the flicker testers under different flicker signals
As can be seen from fig. 7 to fig. 12 and table 2, for a voltage flicker signal with a small fluctuation frequency (e.g. 0.5 Hz), the IEC61000-4-15 standard flicker tester has good overall adaptability and stability, and can be used for detecting a dynamic signal, although there is a certain error when the fluctuation frequency is small because the fluctuation frequency approaches the non-ideal amplitude-frequency characteristic of the filter caused by the cut-off frequency of the filter, the flicker value can be basically detected; the flicker meter based on the envelope decomposition method can accurately detect the flicker magnitude when a flicker signal is constant or the fluctuation amplitude value is suddenly changed, but when the signal fluctuation amplitude value is alternately fluctuated, the envelope decomposition method causes a larger result due to the generation of frequency spectrum leakage, so that the conclusion is wrong. Therefore, the level signal can be used for screening a flicker tester based on an envelope decomposition method.
Claims (1)
1. An analog input type flicker tester discrimination method is characterized in that: the method comprises the following steps:
testing the analog quantity input type flicker tester by adopting an IEC61000-4-15 standard test signal, and preliminarily judging whether the analog quantity input type flicker tester meets the design requirements of the IEC61000-4-15 flicker test standard, namely whether the error is within the range of +/-5 percent according to the IEC61000-4-15 standard; specifically, IEC61000-4-15 flicker signal u is generated according to IEC61000-4-15 flicker standard AM (t)＝A[1+m f cos(Ω f t+θ f )]cos ω t, where A and ω represent the amplitude and angular frequency of the power frequency carrier voltage, m f 、Ω f And theta f Respectively representing amplitude coefficient, angular frequency and phase of the amplitude-modulated wave voltage, determining initial phase as 0, and duration as 10min, and determining short-time flicker theory value P st ＝0.7139×4K f R f ·100d f Wherein, K is f 、R f And d f The visual sensitivity coefficient, the form factor and the fluctuation size of the fluctuation frequency are respectively;
constructing a level flicker signal which is a first signal, a second signal and a third signal respectively; the first signal is used for judging whether the analog input type flicker tester is strictly designed according to IEC61000-4-15 flicker test standards, the second signal is used for judging whether the analog input type flicker tester is designed based on an average value statistical method, and the third signal is used for judging whether the analog input type flicker tester is designed based on a signal envelope decomposition method; the concrete structure is as follows:
the first signal: setting a flicker test signal uf1 (t) with 10min of sudden change of fluctuation size, wherein the fluctuation size is suddenly changed from df to 0.25df at the 70s, and the phase is equal to the initial phase when in sudden change, thenA. Omega respectively represents the amplitude and angular frequency of the power frequency carrier voltage, and df and omega f respectively represent the fluctuation size and angular frequency of the amplitude modulated wave voltage;
a second signal: setting a flicker test signal uf2 (t) with an abrupt change in the amplitude of the fluctuation of 10min, the amplitude of which at a time tb abruptly changes from df to a df, where a<1，60s<t b &300s, when the phase is suddenly changed, the phase is equal to the initial phase,
the third signal: flicker test signal u with alternating fluctuation f3 (t) containing a flicker signal of 0.5Hz sine amplitude modulation wave, circulating the flicker signal in a group at a time interval of 15s, wherein the fluctuation value of the first 5s is 2.34 percent of the sine amplitude modulation wave of 0.5Hz, the fluctuation value of the last 10s is reduced to 1/4 of the first 5s, circulating for 40 times in total and lasting for 10min, and the phase when the fluctuation value is changed is equal to the initial phase,wherein n =0, 1, \8230, 39;
the constructed level flicker signal is adopted to test the analog input type flicker tester, and whether the analog input type flicker tester is strictly designed according to IEC61000-4-15 flicker test standards or not is further judged, namely whether the error is within the range of +/-5% or not is judged according to the IEC61000-4-15 standards or whether the analog input type flicker tester is designed based on an average statistical method or not, namely whether the error between a flicker test value and a theoretical value based on the average statistical method is within the range of +/-5% or whether the analog input type flicker tester is designed based on a signal envelope decomposition method or not is judged, namely whether the error between the flicker test value and the theoretical value based on the signal envelope decomposition method is within the range of +/-5%.
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