KR101341448B1 - Method and apparatus for calculating iec short-term flicker index using half-cycle rms voltage - Google Patents

Abstract

Provided are a calculation method of an IEC short-term flicker evaluation index using a half-cycle effective voltage and a device thereof. According to an embodiment of the present invention, a digital flicker meter which calculates a flicker evaluation index under an AC power system includes: a first block which calculates a normalized voltage effective value from a converted digital signal every half cycle of the nominal voltage of the power system; a second block which removes the offset included in the calculated voltage effective value and applies weighted voltage variation to the signal from which the offset is removed in response to the lamp-eye-brain sensitivity; a third block which squares the signal onto which the weighted value is applied, in order to simulate non-linear eye-brain perception, and estimates a momentary flicker level by computing the moving average of the squared signal in order to simulate the memory effect of the brain; and a fourth block which calculates an IEC flicker evaluation index based on the estimated momentary flicker level. [Reference numerals] (610) Block 1; (620) Block 2; (630) Block 3; (640) Block 4; (AA) Calculate a normalized half-cycle effective value (normalized H-RMS); (BB) High pass filter (HPF) and a weighting filter; (CC) Squaring unit and a sliding mean filter; (DD) Statistical analysis

Description

METHODS AND APPARATUS FOR Calculating IEC Short-term Flicker Evaluation Index Using Half-Period Effective Value Voltage

This embodiment relates to a method and apparatus for calculating an IEC short-term flicker evaluation index (Pst) using a half-cycle effective value voltage. More specifically, the present invention relates to a method and apparatus for calculating an IEC short-term flicker evaluation index that simplifies a short-term flicker evaluation method of the existing IEC standard by using a half-cycle effective value voltage.

The contents described in this section merely provide background information on the present embodiment and do not constitute the prior art.

If the amount of current changes drastically due to increased use of non-linear loads such as arc furnaces, welding machines, industrial induction motors, or starting of large motors, the periodic voltage fluctuations of nearby loads cause power quality degradation. . Most home appliances and electrical equipment are equipped with suitable voltage filters, so they are not significantly affected by minute voltage changes. However, in the case of a light load, a change in the input voltage immediately leads to a blinking of the light, which is recognized as a power quality problem for the general user, and causes psychological discomfort.

Flicker is a phenomenon in which the brightness of the light fluctuates due to the voltage fluctuation of the power applied to the light load. In general, the blinking of a light that can be felt by the human eye is 50 times or less per second, especially when it is about 10 to 25 times per second.

The International Electrotechnical Commission (hereinafter referred to as the "IEC") enacted the IEC 868 Standard on how to measure analog flicker for 230V-60W incandescent lamps, and subsequently added the standard for 120V-60W incandescent lamps in the United States. 61000-4-15 has been published. In the IEC standard, the short-term flicker evaluation index (Pst; P stands for 'perturbation', st stands for 'short-term') and the long-term flicker rating index (Plt; P stands for 'perturbation', and lt is 'long' -term '). Korea has also enacted and revised electrical quality standards based on IEC standards.

1 is a simplified block diagram of a flicker meter according to the IEC standard (IEC 61000-4-15).

As shown in Fig. 1, the flicker meter proposed by the IEC standard is based on an analog signal, and a block (block 2 to block 4) and a numerical value that largely define the chain-reaction relation of the lamp-eye-brain to the variation of the input voltage. It consists of a statistical analysis block (block 5) that yields a typical flicker evaluation index (Pst, Plt).

Block 1 110 normalizes the input voltage signal to a reference level as a first step. That is, the input voltage signal is divided by the effective value and scaled to the reference level. Block 2 120 squares the normalized input voltage signal to produce an envelope of voltage variation. Block 3 (130) passes the band-pass filter (Band-Pass Filter) to remove the components having a frequency twice the frequency (Input Carrier Frequency) of the DC voltage and the basic voltage signal to extract the envelope component of the voltage variation, The weighting filter reflects the sensitivity of the human visual system to the flicker frequency. Block 4 passes a Square Multiplier and a Moving Mean Filter to simulate the brain's memory effect. The weight filter of block 3 (140) and the two filters constituting block 4 are called Van Doorn Model, through which the voltage variation can be expressed as a visual change corresponding thereto. The result of up to block 4 (110-140) is called Instantaneous Flicker Level (IFL). Block 5 150 converts the instantaneous flicker level into a numerical exponent Pst that can assess the degree of flicker. In particular, block 5 150 may be implemented as a microprocessor that performs online statistical analysis at the flicker level.

As above, the IED standard defines flicker meters as analog implementation specifications. Therefore, when the digital flicker meter is implemented, it is necessary to adjust the number of sampling data through down sampling according to each block.

This embodiment provides a flicker index measurement algorithm that is advantageous for the implementation of a digital flicker meter by simplifying the procedure for obtaining the instantaneous flicker level through the half-cycle effective value calculation in the flicker meter according to the IEC standard shown in FIG. There is a main purpose.

According to one aspect of the present embodiment for achieving the above object, in the method for calculating the instantaneous Flicker Level (IFL) required to calculate the IEC short-term flicker evaluation index (Pst) under AC power system, A first process of acquiring a digital signal by sampling an input voltage from a system at a predetermined sampling period, a second process of calculating a normalized voltage rms value of sampling values included in the half-period at every half-cycle of the nominal voltage of the power system, A third process of removing the offset due to the nominal voltage from the normalized voltage rms and weighting the signal from which the offset is removed in correspondence with a lamp-eye-brain sensitivity And the memory effect of the brain after squaring the weighted signal to simulate non-linear eye-brain perception. And a fourth process of calculating the instantaneous flicker level by calculating a moving mean to simulate the sliding mean.

In the second process, the normalized voltage rms value is calculated by calculating a voltage rms value of sampling values included in the corresponding half period for each half period of the nominal voltage from the sampling value of the input voltage, and dividing it by the average effective value for a predetermined period. can do.

In the second process, the sampling value of the input voltage is divided by the average effective value for a predetermined period to normalize the sampling value of the input voltage, and then the voltages of the normalized sampling values included in the corresponding half period for each half period of the nominal voltage. By calculating the rms value, the normalized voltage rms value can be calculated.

The calculation of the voltage rms of the sampling values may be an operation of obtaining a square root of a root mean square value of the sampling values included in the corresponding half period.

로 표현될 수 있고, 여기서 Vrms[k]는 k번째 반주기의 전압 실효치, N은 반주기 동안의 샘플링 개수, v[i]는 i번째 샘플링 값이다.In addition, the operation of calculating the voltage effective value of the sampling values,

Where Vrms [k] is the voltage effective value of the k-th half period, N is the number of samples during the half-cycle, and v [i] is the i-th sampling value.

According to another aspect of the present embodiment, a first process of acquiring a digital signal by sampling an input voltage from a power system in a predetermined sampling period, and normalized voltages of sampling values included in the corresponding half period for every half cycle of a nominal voltage of the power system A second process of calculating an effective value, a third process of removing an offset due to the nominal voltage from the normalized voltage effective value and assigning a weight to the signal from which the offset is removed in correspondence with light-eye-brain sensitivity An online statistic based on the fourth process of calculating the instantaneous flicker level by squaring the weighted signal to simulate brain perception and then calculating a moving average to simulate the memory effect of the brain And a fifth process of calculating the IEC short-term flicker evaluation index through analysis. Provides a calculation of the IEC short-term flicker rating scale method.

According to another aspect of the present embodiment, an input unit for acquiring a voltage waveform signal from a power system, a converter for sampling the acquired voltage waveform signal at a predetermined sampling period and converting the signal into a digital signal, and a nominal value of the power system from the converted digital signal The normalized voltage rms is calculated every half period of voltage, the offset due to the nominal voltage included in the calculated voltage rms is eliminated, and the voltage from which the offset is removed is weighted in response to light-eye-brain sensitivity. Square the weighted signal to simulate the nonlinear eye-brain perception, compute the instantaneous flicker level by calculating a moving average over the squared signal to simulate the brain's memory effects, and base the estimated instantaneous flicker level on the basis of the calculated instantaneous flicker level. It characterized in that it comprises a calculation unit for calculating the IEC flicker evaluation index to It provides digital flicker meter.

The calculation unit normalizes the sampling value of the voltage waveform signal by dividing the sampling value of the voltage waveform signal by the average effective value for a predetermined period, and then selects the voltage effective value of the normalized sampling values included in the corresponding half period for each half period of the nominal voltage. By calculating, the normalized voltage rms can be calculated.

In addition, the calculation unit calculates the voltage effective value of the sampling values included in the corresponding half cycle for each half cycle of the nominal voltage from the sampling value of the voltage waveform signal, and divides it by the average effective value for a predetermined period. Can be calculated

According to another aspect of the present embodiment, the first block for calculating the normalized voltage rms value every half cycle of the nominal voltage of the power system, the offset by the nominal voltage included in the calculated voltage rms from the converted digital signal, and offset The second block, which weights the voltage variation in response to light-eye-brain sensitivity, squares the weighted signal to simulate the brain's memory effect, A digital flicker meter comprising a third block for calculating a moving average of a squared signal to calculate an instantaneous flicker level and a fourth block for calculating an IEC short-term flicker evaluation index based on the calculated instantaneous flicker level.

The second block has a high pass filter (blocking frequency of 0.05 Hz) that removes the offset due to the nominal voltage included in the calculated voltage rms, and weights the voltage variation in response to the light-eye-brain sensitivity to the signal from which the offset is removed. It may include a weight filter to give.

The third block is a squarer that squares a weighted signal to simulate nonlinear eye-brain perception and a moving average filter that calculates the instantaneous flicker level by calculating a moving average of the squared signal to simulate the memory effect of the brain. It may include.

According to another aspect of this embodiment, a computer readable recording medium storing instructions, when executed by a digital flicker meter that calculates a flicker evaluation index under an AC power system, causes the digital flicker meter to acquire from a power system. The voltage waveform signal is sampled at a predetermined sampling period and converted into a digital signal, and each half cycle of the nominal voltage of the power system, the normalized voltage rms value of the sampling values included in the half cycle is calculated and included in the calculated voltage rms. Remove the offset due to the nominal voltage, weight the voltage variation in response to the light-eye-brain sensitivity, and apply the weighted signal to simulate the nonlinear eye-brain perception. Squared and simulate the brain's memory effect By calculating a moving average of the squared signal, to design and to estimate the instantaneous level of flicker, there is provided a readable recording medium in which to calculate the IEC flicker evaluation index based on the estimated instantaneous flicker value, computer.

As described above, according to the present embodiment, the flicker measurement algorithm of the existing IEC standard can be simplified.

In addition, according to the present embodiment, the data storage capacity is significantly reduced as the number of sampling data is determined to be twice the nominal frequency per second (for example, 120 per second when the nominal frequency is 60 Hz) through the half-cycle effective value calculation. Therefore, there is a very advantageous advantage in reducing the processor burden when implementing the digital flicker meter.

In addition, the present embodiment can be expected to unify the existing method of calculating the power quality evaluation index which is divided into instantaneous values and effective values based on effective values.

1 is a diagram illustrating a method of calculating the flicker index according to the IEC standard.
FIG. 2 is a diagram illustrating an input voltage signal (a) including a flicker signal having a voltage variation of 40% and 10 Hz in a reference voltage signal of 220 Vrms and 60 Hz, and a Fourier transform result (b) thereof.
Fig. 3 is a diagram showing a signal waveform (a) in which an input voltage signal is normalized and a Fourier transform result (b) thereof.
4 is a diagram showing an output waveform (a) of squared normalized signals and a Fourier transform result (b) thereof.
5 is a diagram showing an output waveform (a) passing through a bandpass filter and a Fourier transform result (b) thereof.
6 is a schematic block diagram of a flicker meter according to the present embodiment.
FIG. 7 is a diagram illustrating an output waveform (a) and a Fourier transform result (b) in which half-cycle effective value calculation and normalization are performed on an input voltage signal.
Fig. 8 is a diagram showing an output waveform (a) and a Fourier transform result (b) having a normalized half-cycle effective value passed through a high pass filter.
9 is a schematic block diagram of a digital flicker meter according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In addition, in describing the component of this invention, terms, such as 1st, 2nd, A, B, (a), (b), can be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. Throughout the specification, when an element is referred to as being "comprising" or "comprising", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise . When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be "connected," "coupled," or "connected. &Quot;

In this embodiment, the low pass filter included in the bandpass filter of blocks 1 (110), 2 (120), and 3 (130) of the flicker meter according to the IEC standard shown in FIG. As a result, the result is to simplify the flicker index measurement algorithm according to the IEC standard.

First, assuming that an input voltage signal obtained by synthesizing a flicker signal having a voltage variation of 40% and 10 Hz to a reference voltage signal of 220 Vrms and 60 Hz, which is a nominal voltage of a domestic home, is used for each flicker meter according to the IEC standard shown in FIG. An output waveform of the block is illustrated and a corresponding algorithm of the simplified flicker meter according to the present invention will be described.

end. IEC Flicker  Input waveform of block 1 on the meter

FIG. 2 is a diagram illustrating an input voltage signal (a) including a flicker signal having a voltage variation of 40% and 10 Hz in a reference voltage signal of 220 Vrms and 60 Hz, and a Fourier transform result (b) thereof.

As shown in (a) of FIG. 2, a voltage change of 10 Hz means that the input voltage signal rises and falls 10 times per second, that is, 20 fluctuations (10 rises and 10 fall) by the flicker signal. In addition, the voltage variation of 40% means that the voltage variation is + 20% and -20% based on the reference voltage signal, and the rising and falling widths are 0.2 when the reference voltage signal is normalized to the reference level 1. It has a size component of.

As a result, the flicker meter must extract a signal having a frequency component of 10 Hz and a magnitude component of 0.2 from the input voltage signal.

If the above input voltage signal is mathematically represented, Equation (1).

은 기준전압신호의 최대값,

는 기준전압신호의 주파수(혹은 계통주파수),

는 전압변동의 크기 ,

는 전압변동주파수를 의미한다. 위 입력전압신호는 220Vrms, 60Hz의 기준전압신호에 40%, 10Hz의 전압변동을 갖는 플리커 신호가 포함되어 있으므로,

은

,

는 60,

는 0.4,

는 10이다. here,

Is the maximum value of the reference voltage signal,

Is the frequency (or grid frequency) of the reference voltage signal,

Is the magnitude of the voltage variation ,

Is the voltage fluctuation frequency. Since the input voltage signal includes a flicker signal having a voltage variation of 40% and 10Hz in the reference voltage signal of 220Vrms and 60Hz,

silver

,

Is 60,

Is 0.4,

Lt; / RTI >

Expanding Equation 1 above and separating each frequency component into Equation 2 is performed.

It can be seen from Equation 2 that the input voltage signal includes a 60 Hz component of amplitude 311, a 50 Hz component of amplitude 31 and a 70 Hz component of amplitude 31. This can be confirmed from the Fourier transform result of FIG.

I. IEC Flicker  Output waveform of block 1 on the meter

Fig. 3 is a diagram showing a signal waveform (a) in which an input voltage signal is normalized and a Fourier transform result (b) thereof.

Block 1 110 divides the input voltage signal by the effective value of the reference voltage signal and normalizes it to the reference level. Therefore, the output signal of block 1 is expressed by Equation 3.

It can be seen from Equation 3 that the normalized output signal includes a 60 Hz component (normalized value) of amplitude 1, a 50 Hz component of amplitude 0.1, and a 70 Hz component of amplitude 0.1. This can be confirmed from the Fourier transform result of FIG.

All. Output waveform of block 2 on IEC flicker meter

4 is a diagram showing an output waveform (a) of squared normalized signals and a Fourier transform result (b) thereof.

Block 2 120 squares the normalized input voltage signal to double the frequency instead of inverting the value with the negative phase. This is expressed mathematically as Equation 4.

은 크기가 작으므로, 수학식 4에서

를 포함하는 마지막 항은 무시할 수 있다. 따라서 블록 2(120)의 출력 신호는 수학식 5와 같이 간략화할 수 있다.Generally

Since is small in size,

The last term containing may be ignored. Therefore, the output signal of the block 2 120 can be simplified as shown in Equation 5.

It can be seen from Equation 5 that the output signal of block 2 (120) includes a DC component of amplitude 0.5, a 10 Hz component of amplitude 0.2, a 120 Hz component of amplitude 0.5, a 110 Hz component of amplitude 0.1 and a 130 Hz component of amplitude 0.1. This corresponds to the Fourier transform result shown in FIG. As a result, when the square is performed on the normalized input voltage signal, it can be seen that the DC component, the frequency component of the flicker signal, twice the frequency of the reference voltage signal, and the frequency component of the frequency ± flicker signal of the reference voltage signal are output.

la. IEC Flicker  Output waveform of block 3 on the meter

Block 3 (130) passes the input signal through a bandpass filter to extract the envelope component of the voltage fluctuations, and the weight filter provides sensitivity to the flicker frequency of the human visual system, i.e., lamp-eye-brain sensitivity. Brain Sensitivity).

5 is a diagram showing an output waveform (a) passing through a bandpass filter and a Fourier transform result (b) thereof.

According to the IEC standard, for an input signal with a nominal frequency of 60 Hz, the band pass filter consists of a low pass filter with a cutoff frequency of 42 Hz and a high pass filter with a cutoff frequency of 0.05 Hz. Through this, it is possible to extract the 10Hz frequency component, which is the voltage variation component. That is, the DC component is removed through the high pass filter, and the 120 Hz component due to the reference voltage signal and the 110 Hz and 130 Hz components that are the combined components of the reference voltage signal and the voltage variation are removed through the low pass filter.

As a result of passing through the bandpass filter, as shown in the waveform (a) and the Fourier transform result (b) of FIG. 5, the 10 Hz component having a magnitude of 0.2 (40%, corresponding to a voltage variation of 10 Hz) is extracted.

In other words, the flicker meter according to the IEC standard extracts the voltage variation component from the input voltage signal through the band pass filter of blocks 1 (110), 2 (120), and 3 (130).

Now, the flicker index calculation algorithm according to the present embodiment will be described.

As described above, this embodiment is a part of the block 1 (110), block 2 (120) and block 3 (130) of the functional blocks (110-150) of the flicker meter according to the above IEC standard (in the bandpass filter Its main purpose is to replace or simplify the included lowpass filter using half-cycle effective method. In other words, the algorithm for calculating the flicker evaluation index according to the IEC standard illustrated in FIG. 1 through the half-cycle effective value calculation method will be simplified as shown in FIG. 6.

6 is a schematic block diagram of a flicker meter according to the present embodiment.

In block 1 610, the RMS calculation algorithm according to the present embodiment calculates the half-cycle voltage RMS value with respect to the input voltage signal. The signal is divided by the voltage rms of the reference voltage signal to obtain a normalized half-cycle voltage rms. According to an exemplary embodiment, after normalizing the input voltage signal, the half-cycle voltage rms value may be calculated based on the normalized signal. A mathematical operation for calculating the half-cycle effective value is shown in Equation 6.

Here, Vrms is the half-cycle effective value, T is the period of the reference voltage signal, v (t) is the input voltage signal.

Discrete expression of equation (6) is the same as equation (7).

Here, N means the number of sampling during the half cycle.

Block 2 620 passes a high pass filter and a weighted filter having a predetermined cutoff frequency. The high pass filter has a cutoff frequency of 0.05 Hz. The high pass filter removes the offset component due to the reference voltage signal included in the normalized voltage rms output of the block 1 610. The weight filter assigns a weight value for each frequency in response to the electric light-eye-brain sensitivity to the voltage rms with the offset component removed, and has the same configuration as the weight filter of block 3 130 according to the IEC standard.

Block 3 630 and block 4 640 are performed with the same procedure as block 4 140 and block 5 150 of the IEC standard shown in FIG. 1, respectively.

Simulation results performed to verify the performance of the flicker index calculation algorithm according to the present embodiment are as follows.

In this simulation, the same signal as the input voltage signal of FIG. 2 was used as the input voltage signal. That is, an input voltage signal obtained by synthesizing a flicker signal having a voltage variation of 40% and 10 Hz with a reference voltage signal of 220 Vrms and 60 Hz was used.

FIG. 7 is a diagram illustrating an output waveform (a) in which half-cycle effective value calculation and normalization are performed on an input voltage signal, and a discrete Fourier transform result (b) thereof.

When the input voltage signal passes through block 1 610 of FIG. 6, since the reference voltage signal is 60 Hz, 120 half-cycle effective values are obtained per second. Dividing this by the voltage effective value 220V of the reference voltage signal gives a normalized half-cycle effective value as shown in FIG. The normalized half-cycle effective value includes a voltage variation (40%) including an offset component according to the reference voltage signal. That is, it has a value that oscillates up to ± 0.2 on the basis of 1. Note that the half-cycle effective values are discrete values, but in FIG. 7A, the half-cycle effective values are shown in connection with each other to clarify the contrast with FIG. 5A.

Next, when a high pass filter with a cutoff frequency of 0.05 Hz (same as the IEC standard) is passed to the normalized half-cycle effective value, the offset component according to the reference voltage signal is removed, and a 10 Hz of 0.2 The component (voltage fluctuation component) is extracted. 8 shows this result.

Fig. 8 is a diagram showing an output waveform (a) and a Fourier transform result (b) having a normalized half-cycle effective value passed through a high pass filter.

Comparing this with FIG. 5, it can be seen that the same result as the result according to the IEC standard (see FIG. 5) is obtained.

Therefore, a part of the block 1 (110), block 2 (120) and block 3 (130) (low pass filter included in the band pass filter) of Figure 1 according to the IEC standard through the half-cycle effective value calculation algorithm according to this embodiment It can be seen that it can be replaced. Subsequent procedures follow the same procedure as blocks 4 and 5 according to the IEC standard.

Meanwhile, when the flicker meter shown in FIG. 6 is implemented as a digital flicker meter, the input voltage signal may be sampled at a predetermined frequency and converted into a discrete signal before being input to the block 1 610.

9 is a schematic block diagram of a digital flicker meter according to an embodiment of the present invention.

The digital flicker meter 900 according to an embodiment of the present invention includes an input unit 910 for acquiring a voltage waveform signal at a predetermined time interval in a power system, and sampling the acquired voltage waveform signal at a predetermined sampling period to convert the digital signal into a digital signal. The converter 920 and the calculator 930 performed by blocks 610 to 650 illustrated in FIG. 6 are included.

In particular, the calculation unit 930 calculates a normalized voltage rms value every half cycle of the nominal voltage of the power system from the digital signal received from the converter, removes the offset by the nominal voltage included in the calculated voltage rms, and removes the offset. Weighted signals are weighted in response to Lamp-Eye-Brain Sensitivity, and the weighted signals are simulated to simulate Non Linear Eye-Brain Perception. In order to simulate the memory effect of the brain, the squared signal is calculated by calculating a sliding mean, and the instantaneous flicker level is calculated, and the IEC flicker evaluation index is calculated based on the calculated instantaneous flicker value.

In the case of modularizing each function performed by the calculator 930, the calculator 930 may calculate a voltage rms calculation module 931 for calculating a normalized voltage rms value every half cycle of the nominal voltage of the power system from the digital signal received from the converter. High pass filter module 932 for removing offset due to nominal voltage included in calculated voltage rms, weight filter module 933 for weighting voltage variation in response to light-eye-brain sensitivity to signals with offset removed Squarer first-order lowpass filter module that squares weighted signals to simulate nonlinear eye-brain perception and computes instantaneous flicker levels by computing moving averages of squared signals to simulate brain memory effects 934 and a flicker evaluation index calculation module 935 that calculates an IEC flicker evaluation index based on the calculated instantaneous flicker value.

According to an embodiment, the display unit may further include a display unit (not shown) for displaying the calculated flicker measurement index or a communication unit (not shown) for transmitting the calculated flicker measurement index to the outside.

Meanwhile, the functions performed by the blocks 610 to 650 illustrated in FIG. 6 may be implemented as computer readable codes on a computer readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. That is, a computer-readable recording medium includes a magnetic storage medium (for example, a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (for example, CD ROM, And the like). The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

The foregoing description is merely illustrative of the technical idea of the present embodiment, and various modifications and changes may be made to those skilled in the art without departing from the essential characteristics of the embodiments. Therefore, the present embodiments are to be construed as illustrative rather than restrictive, and the scope of the technical idea of the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment should be construed according to the following claims, and all technical ideas within the scope of equivalents thereof should be construed as being included in the scope of the present invention.

900: digital flicker meter 910: input unit
920: converter 930: arithmetic unit
931: half cycle effective value calculation module 932: high pass filter module
933: weight filter module
934: Squarer and Moving Average Filter Module
935: Flicker Evaluation Index Calculation Module

Claims (17)

In a method of calculating the instantaneous flicker level (IFL) required to calculate the IEC short-term flicker evaluation index (Pst) under an AC power system,
A first step of sampling the input voltage from the power system in a predetermined sampling period to obtain a digital signal;
A second step of calculating a normalized voltage rms value of sampling values included in a corresponding half period for each half period of a nominal voltage of the power system;
A third process of removing the offset due to the nominal voltage from the normalized voltage rms and weighting the signal from which the offset is removed in correspondence with a lamp-eye-brain sensitivity ; And
A method for estimating instantaneous flicker levels by squaring the weighted signal to simulate non-linear eye-brain perception and then calculating a sliding mean to simulate the memory effect of the brain. 4 courses
Method for calculating the instantaneous flicker level comprising a. The method of claim 1,
In the second process,
By dividing the sampling value of the input voltage by the average effective value for a predetermined period to normalize the sampling value of the input voltage, and through the method of calculating the voltage effective value of the normalized sampling values included in the half cycle for each half period of the nominal voltage And calculating the instantaneous flicker level. The method of claim 1,
In the second process,
Calculating a normalized voltage rms value by calculating a voltage rms value of sampling values included in a corresponding half period for each half period of the nominal voltage from a sampling value of the input voltage, and dividing it by an average rms value for a predetermined period. How to calculate the flicker level at the moment. The method according to claim 2 or 3,
Calculation of the voltage effective value of the sampling values,
And calculating a square root of a squared mean value with respect to sampling values included in the corresponding half period. 5. The method of claim 4,
Calculation of the voltage effective value of the sampling values,

Wherein Vrms [k] is the voltage effective value of the k-th half period, N is the number of samples during the half-cycle, and v [i] is the i-th sampling value. In the method of calculating the IEC short-term flicker evaluation index,
A first step of sampling the input voltage from the power system in a predetermined sampling period to obtain a digital signal;
A second step of calculating a normalized voltage rms value of sampling values included in a half cycle of the nominal voltage of the power system;
Removing a offset due to the nominal voltage from the normalized voltage rms and assigning a weight to the signal from which the offset is removed in correspondence with a light-eye-brain sensitivity;
A fourth step of calculating an instantaneous flicker level by squaring the weighted signal to simulate nonlinear eye-brain perception, and then calculating a moving average to simulate the memory effect of the brain; And
A fifth process of calculating the IEC short-term flicker evaluation index through online statistical analysis based on the instantaneous flicker level
Method of calculating the IEC short-term flicker evaluation index comprising a. The method according to claim 6,
In the second process,
By dividing the sampling value of the input voltage by the average effective value for a predetermined period to normalize the sampling value of the input voltage, and through the method of calculating the voltage effective value of the normalized sampling values included in the half cycle for each half period of the nominal voltage And calculating the normalized voltage rms value. The method according to claim 6,
In the second process,
The normalized voltage effective value is calculated by calculating a voltage effective value of sampling values included in the corresponding half period for each half period of the nominal voltage from the input value of the input voltage, and dividing by the average effective value for a predetermined period. Calculation method of IEC short-term flicker evaluation index. In the digital flicker meter which calculates flicker evaluation index under AC power system,
An input unit for acquiring a voltage waveform signal from a power system;
A converter for sampling the acquired voltage waveform signal at a predetermined sampling period and converting the converted voltage waveform into a digital signal; And
From the converted digital signal, the normalized voltage rms are calculated every half cycle of the nominal voltage of the power system, the offset by the nominal voltage included in the calculated voltage rms is removed, and the light-eye-brain sensitivity is applied to the signal from which the offset is removed. Weights the voltage fluctuations in response to the signal, squares the weighted signal to simulate nonlinear eye-brain perception, and computes a moving average for the squared signal to simulate the brain's memory effect. A calculation unit that calculates and calculates the IEC flicker evaluation index based on the calculated instantaneous flicker level
Digital flicker meter comprising a. 10. The method of claim 9,
The operation unit,
After dividing the sampling value of the voltage waveform signal by the average effective value for a predetermined period, normalizing the sampling value of the voltage waveform signal, and calculating the voltage effective value of the normalized sampling values included in the corresponding half period for each half period of the nominal voltage. And estimating the normalized voltage rms. 10. The method of claim 9,
The operation unit,
The normalized voltage rms value is calculated by calculating a voltage rms value of the sampling values included in the half cycle of the nominal voltage from the sampling value of the voltage waveform signal and dividing by the average rms value for a predetermined period. Digital flicker meter. The method according to claim 10 or 11,
The method of calculating the voltage effective value is
And a method of calculating a square root of a squared mean value with respect to sampling values included in the corresponding half period. The method of claim 12,
The method of calculating the voltage effective value is

Wherein Vrms [k] is the voltage effective value of the k-th half period, N is the number of samples during the half-cycle, and v [i] is the i-th sampling value. A digital flicker meter that calculates an IEC short-term flicker rating index under an AC power system,
A first block for calculating a normalized voltage rms value every half cycle of the nominal voltage of the power system from the converted digital signal;
A second block for removing an offset due to the nominal voltage included in the calculated voltage rms and weighting the voltage variation in response to the light-eye-brain sensitivity to the signal from which the offset is removed;
A third block that squares the weighted signal to simulate non-linear eye-brain perception, and calculates an instantaneous flicker level by calculating a moving average of the squared signal to simulate the memory effect of the brain; And
Fourth block for calculating the IEC short-term flicker evaluation index based on the calculated instantaneous flicker level
Digital flicker meter, including. 15. The method of claim 14,
The second block is,
A high pass filter for removing offset due to nominal voltage included in the calculated voltage rms and a weight filter for weighting the voltage variation in response to the light-eye-brain sensitivity to the signal from which the offset is removed. Digital flicker meter. 15. The method of claim 14,
The third block,
A squarer that squares the weighted signal to simulate nonlinear eye-brain perception, and a moving average filter that calculates the instantaneous flicker level by calculating a moving average of the squared signal to simulate the brain memory effect. Digital flicker meter. A computer-readable recording medium storing instructions,
When executed by a digital flicker meter that calculates the flicker evaluation index under an AC power system, the digital flicker meter causes
Sampling the voltage waveform signal obtained from the power system in a predetermined sampling period and converting the voltage waveform signal into a digital signal;
For every half period of the nominal voltage of the power system, calculate a normalized voltage rms value of sampling values included in the half period;
Remove the offset due to the nominal voltage included in the calculated voltage rms;
Weight the voltage fluctuations corresponding to light-eye-brain sensitivity to the signal from which the offset is removed;
Square the weighted signal to simulate nonlinear eye-brain perception;
Calculate the instantaneous flicker level by computing a moving average of the squared signal to simulate the memory effect of the brain;
A computer readable recording medium for calculating an IEC flicker evaluation index based on an estimated instantaneous flicker value.

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