TWI668454B - Flicker analysis device and method - Google Patents

Abstract

A flicker analysis device includes an envelope acquisition unit, a signal conversion unit, a processing unit and an amplitude detection unit. The envelope extraction unit generates an envelope signal related to the flashing signal portion according to a power signal input with a flashing signal portion, and the signal conversion unit converts the envelope signal according to a time-frequency analysis conversion method to generate multiple signals. Conversion signals, each conversion signal has a plurality of frequency values distributed in a time range, the processing unit clusters each conversion signal according to a clustering analysis method to generate a plurality of conversion signals respectively corresponding to The flicker frequency value, the amplitude detection unit detects the envelope signal according to the plurality of flicker frequency values to generate a plurality of flicker amplitude values respectively corresponding to the plurality of flicker frequency values.

Description

Flicker analysis device and method

The invention relates to an analysis device and method, in particular to a scintillation analysis device and method.

The use of non-linear loads in existing power systems has gradually increased, resulting in power quality problems. For example, the power characteristics of the entire power system have changed significantly, and harmonics / interharmonics and voltage flickers have generated power events that interfere with the power system. . Among them, voltage flicker can be divided into periodic and non-periodic flicker according to its nature. The cause of periodic flicker is the repetitive change of large loads, and the cause of non-periodic flicker is an occasional cause, such as the moment of a large motor. Caused by startup. When voltage flicker occurs in the power system, it will inevitably affect the power supplier and the users on the bus bar. Therefore, in order to avoid the serious impact of voltage flicker on the power system, how to accurately assess the severity of voltage flicker has become a very important issue.

At present, the commonly used evaluation indicator for voltage flicker in China is ΔV10 published by the Central Research Institute of Electric Power Industry (CRIEPI), which measures the voltage flicker of power users by using the 10V equivalent value of voltage flicker of 10 Hz. severity. However, because the analysis and evaluation indicators used in China are too old, some voltage flicker specifications IEC 61000-4-15 developed by the International Electrotechnical Commision (IEC) and flicker meter specifications designed to meet this specification are gradually adopted. Evaluate the trend of the severity of voltage flicker. Compared with CRIEPI's ΔV10 indicator, IEC uses statistical methods to calculate a short-term blinking severity indicator and a long-term blinking severity indicator in the voltage flicker specification that it sets to evaluate the severity of voltage flicker, so the assessment is more objective .

Referring to FIG. 1, a flicker analysis device 1 defined by the IEC includes a signal generation unit 11, a square demodulation unit 12, a weighted filter unit 13, a smoothing filter unit 14, and a statistical analysis operation unit 15.

The signal generating unit 11 converts a voltage input signal Vi through an internal parameter converter to generate an rms voltage signal.

The square demodulation unit 12 performs square demodulation processing on the root mean square voltage signal to generate a demodulated signal.

The weighted filter unit 13 includes a band-pass filter 131 and a weighted filter 132. The band-pass filter 131 may be formed by a first-order high-pass filter and a sixth-order Butterworth filter connected in series. The band-pass filter 131 first filters out the DC part of the demodulated signal and the double frequency (120 Hz) component generated by the square demodulation unit 12, and then the weighting filter 132 is given for the visual influence of the human eye. The signal output by the band pass filter 131 is multiplied by a weight to generate a weighted filtered signal.

The smoothing filter unit 14 includes a square multiplier 141 and a first-order low-pass filter 142. The square multiplier 141 performs a square operation on the weighted filtered signal to simulate the non-linear amplification effect of the visual acuity of the human eye to the brain, and generates an operation signal. The first-order low-pass filter 142 can simulate the visual persistence effect of the brain, and generate and output an instantaneous flicker perception value according to the operation signal.

The statistical analysis operation unit 15 calculates and outputs a short-term flicker severity index pst and a long-term flicker severity index plt based on the instantaneous flicker perception value.

However, since the square demodulation unit 12 generates frequency-doubled components, when the voltage input signal Vi has multiple flicker frequency components, the short-term flicker severity index pst and the long-term flicker severity obtained by the flicker analysis device 1 The accuracy of the indicator plt will decrease. Therefore, it is known that the scintillation analysis device 1 still has room for improvement.

Therefore, an object of the present invention is to provide a scintillation analysis device that can overcome the shortcomings of the prior art.

Therefore, the flicker analysis device of the present invention includes an envelope acquisition unit, a signal conversion unit, a processing unit, and an amplitude detection unit.

The envelope extraction unit receives a power signal input with a blinking signal portion, and extracts the upper envelope of the power signal input to generate an envelope signal in the time domain, the envelope signal is related to the blinking signal portion.

The signal conversion unit is electrically connected to the envelope extraction unit to receive the envelope signal, and converts the envelope signal according to a time-frequency analysis conversion method to generate multiple conversion signals, each conversion signal having multiple frequency values , Each frequency value is distributed in a time range.

The processing unit is electrically connected to the signal conversion unit to receive the plurality of conversion signals, and clusters each conversion signal according to a clustering analysis method to generate a plurality of flicker frequency values corresponding to the plurality of conversion signals, respectively.

The amplitude detection unit is electrically connected to the processing unit and the envelope extraction unit to respectively receive the plurality of flicker frequency values and the envelope signal, and detect the envelope signal according to the plurality of flicker frequency values to generate a plurality of The flicker amplitude value corresponding to multiple flicker frequency values.

Therefore, another object of the present invention is to provide a scintillation analysis method that can overcome the shortcomings of the prior art.

Therefore, the scintillation analysis method of the present invention is executed by a scintillation analysis device and includes the following steps:

(A) using the scintillation analysis device to extract an upper envelope of a power signal input with a scintillation signal portion to generate an envelope signal in the time domain, the envelope signal being related to the scintillation signal portion;

(B) using the flicker analysis device to convert the envelope signal according to a time-frequency analysis conversion method to generate multiple conversion signals, each conversion signal has multiple frequency values, and each frequency value is distributed over a time range;

(C) use the scintillation analysis device to cluster each conversion signal according to a cluster analysis method to generate a plurality of flicker frequency values corresponding to the plurality of conversion signals, respectively; and

(D) Use the flicker analysis device to detect the envelope signal according to the multiple flicker frequency values to generate multiple flicker amplitude values corresponding to the multiple flicker frequency values, respectively.

The effect of the present invention is that, by the cooperation of the envelope extraction unit, the signal conversion unit and the processing unit, the plurality of blinking frequency values can be accurately obtained from the blinking signal portion of the voltage input signal, so that the amplitude The detection unit can generate the accurate multiple flicker amplitude values, so as to achieve the purpose of improving the accuracy of a short-term flicker signal evaluation value and a long-term flicker signal evaluation value.

Referring to FIG. 2, an embodiment of the flicker analysis device of the present invention includes a signal input unit 2, an envelope extraction unit 3, a signal conversion unit 4, a processing unit 5, an amplitude detection unit 6, and an arithmetic unit 7.

The signal input unit 2 generates and outputs a power signal input Vin having a blinking signal portion. In this embodiment, the signal input unit 2 may be an element such as an input transformer or a waveform generator that can generate the power signal input Vin, and may output a plurality of the power signal input Vin, but is not limited thereto. Further refer to FIG. 3, which is a measurement diagram of the power signal input Vin.

The envelope extraction unit 3 is electrically connected to the signal input unit 2 to receive the power signal input Vin, and extracts the upper envelope of the power signal input Vin to generate a time-domain envelope signal Es, the envelope signal Es Related to the flashing signal section. In this embodiment, the envelope extraction unit 3 performs a Hilbert transform on the power signal input Vin to obtain the envelope signal Es, but it is not limited thereto. Further refer to FIG. 4, which is a measurement diagram of the envelope signal Es.

The signal conversion unit 4 is electrically connected to the envelope extraction unit 3 to receive the envelope signal Es, and converts the envelope signal Es according to a time-frequency analysis conversion method to generate a plurality of conversion signals Ts1, Ts2, Ts3, Ts4, each converted signal Ts1 ~ Ts4 has multiple frequency values, and each frequency value is distributed in a time range. In this embodiment, the signal conversion unit 4 is a synchronous squeeze converter, and the time-frequency analysis conversion method is a synchronous squeeze conversion method (Synchrosqueezing Transform, SST). The synchronous squeeze conversion method is used to convert the plane of the envelope signal Es from a time-scale plane to a time-frequency plane, and at the same time eliminate interference signals to improve the time-frequency aggregation of each converted signal Ts1 ~ Ts4 to enhance Time-frequency resolution (ie, obtaining a high-resolution time spectrum), and obtaining the frequency components of the flicker signal portion (ie, the conversion signals Ts1 ~ Ts4). Further refer to FIG. 5, which is a measurement diagram of the plurality of conversion signals Ts1 ~ Ts4.

The processing unit 5 is electrically connected to the signal conversion unit 4 to receive the plurality of conversion signals Ts1 ~ Ts4, and clusters each conversion signal Ts1 ~ Ts4 according to a clustering analysis method to generate multiple corresponding to multiple The flicker frequency values f1, f2, f3, f4 of the conversion signals Ts1 ~ Ts4. In this embodiment, the processing unit 5 is an automatic clusterer, and the clustering analysis method is a mean shift clustering method. Further refer to FIG. 6, which is a measurement graph of changes in amplitude of each of the plurality of conversion signals Ts1 ˜ Ts4 versus time and frequency. The processing unit 5 performs cluster analysis on the plurality of converted signals Ts1 to Ts4 shown in FIG. 6, and uses the frequency values corresponding to the plurality of dots F1, F2, F3, and F4 in FIG. 6 as the multiple A flicker frequency value f1, f2, f3, f4.

The amplitude detection unit 6 is electrically connected to the processing unit 5 and the envelope extraction unit 3 to respectively receive the plurality of flicker frequency values f1 ~ f4 and the envelope signal Es, and detect based on the plurality of flicker frequency values f1 ~ f4 The envelope signal Es generates a plurality of flicker amplitude values A1, A2, A3, and A4 corresponding to a plurality of flicker frequency values f1 to f4, respectively. In detail, the amplitude detection unit 6 includes four band-pass filters (not shown). The four band-pass filters are designed according to the plurality of flicker frequency values f1 ~ f4, respectively, to allow the envelope Part of the envelope signal corresponding to the plurality of flicker frequency values f1 to f4 in the signal Es is passed to obtain the plurality of flicker amplitude values A1 to A4, respectively. Further referring to FIG. 7, which is the envelope signal Es corresponding to the multiple flicker amplitude values A1 to A4 corresponding to the multiple flicker frequency values f1 to f4 (ie, the frequencies corresponding to 8 Hz, 13 Hz, 20 Hz, and 29 Hz respectively) To the flicker amplitude value).

The arithmetic unit 7 is electrically connected to the amplitude detection unit 6 to receive the plurality of flicker amplitude values A1 ~ A4, and performs an evaluation operation based on the plurality of flicker amplitude values A1 ~ A4 to generate a short-term flicker signal evaluation value Pst and a long-term Evaluation value of flicker signal Plt. In this embodiment, the arithmetic unit 7 first weights each flicker amplitude value A1 ~ A4, and then performs statistics and analysis on each weighted flicker amplitude value to obtain the short-term flicker signal evaluation value Pst and The long-term flicker signal evaluation value Plt. It should be noted that the short-term flicker signal evaluation value Pst and the long-term flicker signal evaluation value Plt are generated in a known manner, so they will not be described here.

Referring to FIG. 8, it illustrates that the flicker analysis device of this embodiment performs a flicker analysis method to evaluate the severity of flicker of the power signal input Vin. In this embodiment, the scintillation analysis method includes the following steps:

Step 81: Use the signal input unit 2 in the scintillation analysis device to generate and output the power signal input Vin to the envelope extraction unit 3.

Step 82: Use the envelope extraction unit 3 in the scintillation analysis device to extract the upper envelope of the power signal input Vin to generate the envelope signal Es.

Step 83: Use the signal conversion unit 4 in the flicker analysis device to convert the envelope signal Es according to the time-frequency analysis conversion method (ie, the synchronous squeeze conversion method) to generate the plurality of conversion signals Ts1 ~ Ts4.

Step 84: Use the processing unit 5 in the flicker analysis device to cluster each converted signal Ts1 ~ Ts4 according to the clustering analysis method (ie, the mean shift clustering method) to generate the plurality of flicker frequency values f1 ~ f4.

Step 85: Use the amplitude detection unit 6 in the flicker analysis device to detect the envelope signal Es according to the multiple flicker frequency values f1 ˜ f4 to generate the multiple flicker amplitude values A1 ˜ A4.

Step 86: Use the arithmetic unit 7 in the flicker analysis device to perform an evaluation operation based on the multiple flicker amplitude values A1 to A4 to generate the short-term flicker signal evaluation value Pst and the long-term flicker signal evaluation value Plt.

In summary, in this embodiment, by the cooperation of the envelope extraction unit 3, the signal conversion unit 4 and the processing unit 5, the multiple flickers can be accurately obtained from the flicker signal part of the voltage input signal Vi Frequency value f1 ~ f4. In this way, the amplitude detection unit 6 can generate the accurate flicker amplitude values A1 ~ A4, thereby improving the accuracy of the short-term flicker signal evaluation value Pst and the long-term flicker signal evaluation value Plt, and at the same time the flicker Compared with the flicker analysis device 1 established by the conventional IEC, the analysis device does not need to include a square demodulation unit 12, which can avoid the short-term flicker signal evaluation value and the long-term flicker when the voltage input signal Vi has multiple flicker frequency components The problem that the accuracy of the signal evaluation value is reduced.

However, the above are only examples of the present invention, and should not be used to limit the scope of the present invention. Any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still classified as This invention covers the patent.

2‧‧‧Signal input unit

3‧‧‧Envelope acquisition unit

4‧‧‧Signal conversion unit

5‧‧‧Processing unit

6‧‧‧Amplitude detection unit

7‧‧‧ arithmetic unit

81 ~ 86‧‧‧Step

A1 ~ A4‧‧‧ flicker amplitude value

Es‧‧‧Envelope signal

F1 ~ F4‧‧‧ Dots

f1 ~ f4‧‧‧flicker frequency value

Pst‧‧‧ short-term flicker signal evaluation value

Plt‧‧‧Long-term flicker signal evaluation value

Ts1 ~ Ts4‧‧‧Converted signal

Vin‧‧‧Power signal input

Other features and functions of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: FIG. 1 is a block diagram illustrating a conventional flicker analysis device; FIG. 2 is a block diagram illustrating the flicker analysis of the invention An embodiment of the device; FIG. 3 is a measurement diagram illustrating the change of the amplitude of the power signal input of the embodiment with respect to time; FIG. 4 is a measurement diagram illustrating the envelope of the power signal input of the embodiment The change of the amplitude of the line signal with respect to time; FIG. 5 is a measurement chart illustrating the change of the time of each of the multiple conversion signals of the embodiment; FIG. 6 is a measurement chart illustrating the multiple of the embodiment Changes of the respective amplitudes of the converted signals with respect to time and frequency; FIG. 7 is a spectrum diagram illustrating the multiple flicker amplitude values corresponding to the multiple flicker frequency values of the envelope signal of the embodiment; and FIG. 8 is a process The figure illustrates that the flicker analysis device of the embodiment executes a flicker analysis method.

Claims (10)

A flicker analysis device includes: an envelope extraction unit that receives a power signal input with a flicker signal portion and extracts an upper envelope of the power signal input to generate an envelope signal in the time domain, the envelope The signal is related to the blinking signal part; a signal conversion unit, which is electrically connected to the envelope extraction unit to receive the envelope signal, and converts the envelope signal according to a time-frequency analysis conversion method to generate a plurality of conversion signals, Each converted signal has multiple frequency values, and each frequency value is distributed over a time range; a processing unit is electrically connected to the signal conversion unit to receive the multiple converted signals, and converts each converted signal according to a cluster analysis method Performing clustering to generate multiple flicker frequency values corresponding to multiple converted signals; and an amplitude detection unit electrically connecting the processing unit and the envelope extraction unit to receive the multiple flicker frequency values and the envelope, respectively A line signal, and detecting the envelope signal according to the plurality of flicker frequency values to generate a plurality of flicker amplitude values respectively corresponding to the plurality of flicker frequency values. The scintillation analysis device according to claim 1, wherein the envelope extraction unit performs a Hilbert transform on the power signal input to obtain the envelope signal. The flicker analysis device according to claim 1, wherein the signal conversion unit is a synchronous squeeze converter, and the time-frequency analysis conversion method is a synchronous squeeze conversion method. The flicker analysis device according to claim 1, wherein the processing unit is an automatic clusterer, and the clustering analysis method is an average moving clustering method. The scintillation analysis device according to claim 1, further comprising: a signal input unit electrically connected to the envelope extraction unit, and generating and outputting the power signal to the envelope extraction unit; and an arithmetic unit, electrical The amplitude detection unit is connected to receive the plurality of flicker amplitude values and perform an evaluation operation according to the plurality of flicker amplitude values to generate a short-term flicker signal evaluation value and a long-term flicker signal evaluation value. A scintillation analysis method is performed by a scintillation analysis device and includes the following steps: (A) The scintillation analysis device is used to extract an upper envelope of a power signal input with a scintillation signal portion to generate an envelope in the time domain Signal, the envelope signal is related to the flicker signal portion; (B) using the flicker analysis device to convert the envelope signal according to a time-frequency analysis conversion method to generate multiple conversion signals, each conversion signal having multiple frequencies Each frequency value is distributed in a time range; (C) The flicker analysis device is used to cluster each converted signal according to a cluster analysis method to generate multiple flicker frequency values corresponding to the multiple converted signals, respectively. And (D) use the flicker analysis device to detect the envelope signal according to the multiple flicker frequency values to generate multiple flicker amplitude values corresponding to the multiple flicker frequency values. The scintillation analysis method according to claim 6, wherein in step (A), the scintillation analysis device performs a Hilbert conversion on the power signal input to obtain the envelope signal. The flicker analysis method according to claim 6, wherein in step (B), the time-frequency analysis conversion method is a synchronous squeeze conversion method. The flicker analysis method according to claim 6, wherein in step (C), the cluster analysis method is a mean shift clustering method. According to the scintillation analysis method described in claim 6, after step (D), the method further includes the following steps: (E) using the scintillation analysis device to perform evaluation operations based on the plurality of flicker amplitude values to generate a short-term scintillation signal evaluation value And a long-term flash signal evaluation value.