A voltage flicker acceleration detection method, system and medium

Abstract

The application discloses a voltage flicker acceleration detection method, a system and a medium, and relates to the technical field of voltage flicker detection.The voltage flicker acceleration detection method comprises the following steps: squaring a voltage signal to be detected to obtain a voltage square signal; calculating the direct current bias of the voltage square signal; subtracting the direct current bias of the voltage square signal from the voltage square signal to obtain an optimized voltage signal; and performing demodulation filtering, visual sensitivity weighting filtering, squaring, smoothing weighting filtering and statistical processing on the optimized voltage signal to obtain a voltage flicker detection result.The application aims to solve the problem of slow convergence speed of the demodulation filtering of the current IEC flicker detection method, which affects the accuracy of flicker detection, and improve the accuracy of detection while ensuring the speed of flicker detection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power systems, and particularly relates to a voltage flicker acceleration detection method, system and medium. BACKGROUND

[0002] With the development of industrial technology, large power variable loads such as large electric arc furnaces, large rolling mills, electric locomotives and electric welders enter the power grid in large quantities, causing rapid changes in power loads and thus voltage fluctuations and flickers, which seriously affect various electrical equipment operating in the power grid. In order to solve the problem of voltage flicker in the power grid, voltage flicker must be detected in time. At present, the widely used flicker detection method is the IEC flicker detection method recommended by IEC, which includes six steps, namely square detection, demodulation filtering, visual sensitivity weighting filtering, squaring, smoothing weighting filtering and statistical processing. IEC gives the analog transfer function of each link, and in actual engineering application, a microprocessor can be used to realize the above steps by processing the collected sensor signals in a digital signal processing mode. Although this calculation method is simple to implement, the second link demodulation filtering has a slow convergence speed, and the sampling data before convergence cannot be used as invalid data, which affects the accuracy of flicker detection. SUMMARY

[0003] The technical problem to be solved by the application is to provide a voltage flicker acceleration detection method, system and medium to solve the above problems in the prior art, and to improve the accuracy of detection while ensuring the speed of flicker detection.

[0004] To solve the above technical problems, the technical scheme adopted by the application is:

[0005] A voltage flicker acceleration detection method comprises the following steps:

[0006] S101, square the voltage signal to be detected to obtain a voltage square signal;

[0007] S102, calculate the DC bias of the voltage square signal;

[0008] S103, subtract the DC bias of the voltage square signal from the voltage square signal to obtain an optimized voltage signal;

[0009] S104, perform demodulation filtering, visual sensitivity weighting filtering, squaring, smoothing weighting filtering and statistical processing on the optimized voltage signal to obtain a voltage flicker detection result.

[0010] Optionally, the function expression of the voltage signal to be detected in step S101 is:

[0011] ,

[0012] in the above formula, denotes the voltage signal to be detected at time t, is the amplitude of the power carrier voltage, is the amplitude of the amplitude modulation wave voltage, is the angular frequency of the amplitude modulation wave voltage, is time, is the angular frequency of the power carrier voltage; denotes the fluctuating voltage.

[0013] Optionally, the function expression of squaring the voltage signal to be detected to obtain the voltage square signal in step S101 is:

[0014] ,

[0015] in the above formula, denotes the voltage square signal, is the amplitude of the power carrier voltage, is the amplitude of the amplitude modulation wave voltage, is the angular frequency of the amplitude modulation wave voltage, is time, is the angular frequency of the power carrier voltage.

[0016] Optionally, the direct current bias of the voltage square signal in step S102 refers to the average value of the voltage square signal in a time window.

[0017] Optionally, the function expression of obtaining the average value of the voltage square signal in a time window is:

[0018] ,

[0019] in the above formula, denotes the average value of the voltage square signal in a time window, is the size of the time window, is the voltage square signal.

[0020] Optionally, the function expression of subtracting the direct current bias of the voltage square signal from the voltage square signal to obtain the optimized voltage signal in step S103 is:

[0021] ,

[0022] in the above formula, denotes the optimized voltage signal, is the voltage square signal, denotes the average value of the voltage square signal in a time window.

[0023] Optionally, step S104 comprises:

[0024] S201, the optimized voltage signal is filtered by a band-pass filter to remove direct current and components above the second harmonic;

[0025] S202, a visual sensitivity weighting filter is used for visual sensitivity weighting filtering;

[0026] S203, the signal obtained after visual sensitivity weighting filtering is squared to obtain a visual sensitivity weighting filtering square signal;

[0027] S204, the visual sensitivity weighting filtering square signal is extracted by a first-order low-pass filter to extract the direct current component;

[0028] S205, the flicker visual sensitivity S(t) is calculated according to the extracted direct current component, the detected flicker visual sensitivity S(t) is ranked from small to large, the cumulative probability CPF(i) of each level of flicker visual sensitivity S(t) is calculated, and the short-time flicker value P is calculated according to the cumulative probability. st As the obtained voltage flicker detection result.

[0029] Optionally, the bandwidth of the band-pass filter in step S201 is 0.05Hz-35Hz, and the band-pass filter used in the band-pass filtering is composed of a first-order high-pass filter with a cutoff frequency of 0.05Hz and a low-pass filter with a cutoff frequency of 35Hz, wherein the transfer function of the first-order high-pass filter is:

[0030]

[0031] In the above formula, represents the transfer function of the first-order high-pass filter, is the Laplace operator, is the cutoff angular frequency of the high-pass filter; wherein the low-pass filter is a 6th-order Butterworth filter, and the transfer function thereof is:

[0032]

[0033] In the above formula, represents the transfer function of the low-pass filter, is the parameter of the i-th order Butterworth filter, is the Laplace operator, is the cutoff angular frequency of the low-pass filter.

[0034] Optionally, the transfer function of the visual sensitivity weighting filter in step S202 is:

[0035]

[0036] In the above formula, represents the transfer function of the visual sensitivity weighting filter,​​​ For parameters, For the Labras operator, For parameters, , , , For parameters;

[0037] The function expression for calculating the square of the signal obtained after weighted filtering of visual perception in step S203 is as follows:

[0038] ,

[0039] In the above formula, This represents the squared signal weighted by visual perception. The amplitude of the amplitude-modulated wave voltage. This represents the amplitude of the power frequency carrier voltage. The angular frequency of the amplitude-modulated wave voltage. For time;

[0040] The transfer function of the first-order low-pass filter in step S204 is:

[0041] ,

[0042] In the above formula, This represents the transfer function of a first-order low-pass filter. For the Labras operator, n For parameters;

[0043] In step S205, calculating the flicker sensitivity S(t) based on the extracted DC component means multiplying the extracted DC component by... Given the flicker sensitivity S(t), the function expression for calculating the cumulative probability CPF(i) of each flicker sensitivity S(t) is as follows:

[0044] ,

[0045] In the above formula, Let S(t) represent the cumulative probability of the visual perception of the i-th level flicker. For the cumulative time exceeding the i-th level flicker visual sensitivity S(t), The total test time; the short-time flicker value P is calculated based on the cumulative probability. st The function expression is:

[0046] ,

[0047] In the above formula, This is a short-time flicker value. , , , and cumulative probability exceeds a preset threshold in a specified time length of detection time 、 、 、 and flicker visual sensitivity S(t).

[0048] In addition, the application also provides a voltage flicker accelerated detection system, comprising a microprocessor and a memory connected with each other, the microprocessor is programmed or configured to execute the voltage flicker accelerated detection method.

[0049] In addition, the application also provides a computer readable storage medium, the computer readable storage medium stores a computer program, the computer program is used for being programmed or configured by the microprocessor to execute the voltage flicker accelerated detection method.

[0050] Compared with the prior art, the application mainly has the following advantages: based on the IEC flicker detection method, the voltage signal to be detected is squared to obtain a voltage square signal, the DC bias of the voltage square signal is calculated, the voltage square signal is subtracted from the DC bias of the voltage square signal to obtain an optimized voltage signal, then the demodulation filtering, visual sensitivity weighting filtering, squaring, smoothing weighting filtering and statistical processing of the IEC flicker detection method are performed to obtain the voltage flicker detection result, which can effectively accelerate the convergence speed of the band-pass filter, solve the problem of slow convergence speed of the demodulation filtering of the IEC flicker detection method and affect the accuracy of flicker detection, and improve the detection accuracy while ensuring the flicker detection speed. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 is a basic flowchart of the embodiment method of the application.

[0052] Figure 2 is an effect comparison chart of the embodiment method of the application relative to the traditional method. DETAILED DESCRIPTION

[0053] As shown in Figure 1 , the embodiment provides a voltage flicker accelerated detection method, comprising:

[0054] S101, squaring the voltage signal to be detected to obtain a voltage square signal;

[0055] S102, calculating the DC bias of the voltage square signal;

[0056] S103, subtracting the DC bias of the voltage square signal from the voltage square signal to obtain an optimized voltage signal;

[0057] S104, performing demodulation filtering, luminous efficiency weighting filtering, squaring, smoothing weighting filtering and statistical processing on the optimized voltage signal to obtain a voltage flicker detection result.

[0058] Taking a standard flicker as an example of the voltage signal to be detected, the signal frequency f0=50Hz, the fluctuation frequency f1=8.8Hz, the sampling frequency fs=400Hz, the signal effective value is 57.735V, the fluctuation amplitude m=0.25%, and the sampling time window length of single analysis data is 1 minute, that is, the standard flicker is sampled at a sampling rate fs=400Hz within 1 minute.

[0059] In this embodiment, the function expression of the voltage signal to be detected in step S101 is:

[0060] ,

[0061] In the above formula, represents the voltage signal to be detected at time t, is the amplitude of the power carrier voltage, is the amplitude of the amplitude modulation voltage, is the angular frequency of the amplitude modulation voltage, is the time, is the angular frequency of the power carrier voltage; represents the fluctuation voltage. For the standard flicker, we have:

[0062] ,

[0063] ,

[0064] ,

[0065] ,

[0066] wherein, represents the signal frequency, represents the sampling frequency, represents the fluctuation frequency.

[0067] The function expression of the voltage signal to be detected in step S101 in this embodiment is squared to obtain a voltage square signal:

[0068] ,

[0069] In the above formula, represents the voltage square signal, is the amplitude of the power carrier voltage, is the amplitude of the amplitude modulation voltage, is the angular frequency of the amplitude modulation voltage, t is time, ω is the angular frequency of the power carrier voltage.

[0070] In this embodiment, the DC bias of the voltage squared signal in step S102 refers to the average value of the voltage squared signal in the time window. Specifically, the function expression for calculating the average value of the voltage squared signal in the time window in this embodiment is:

[0071]

[0072] In the above formula, represents the average value of the voltage squared signal in the time window, is the size of the time window, is the voltage squared signal.

[0073] In this embodiment, the function expression for obtaining the optimized voltage signal by subtracting the DC bias of the voltage squared signal from the voltage squared signal in step S103 is:

[0074]

[0075] In the above formula, represents the optimized voltage signal, is the voltage squared signal, represents the average value of the voltage squared signal in the time window.

[0076] In this embodiment, step S104 includes:

[0077] S201, passing the optimized voltage signal through a band-pass filter to remove DC and components above the second harmonic;

[0078] S202, performing a visual sensitivity weighted filtering using a visual sensitivity weighted filter;

[0079] S203, calculating the square of the signal obtained after visual sensitivity weighted filtering to obtain a visual sensitivity weighted squared signal;

[0080] S204, extracting the DC component of the visual sensitivity weighted squared signal using a first-order low-pass filter;

[0081] S205, calculating the flicker visual sensitivity S(t) according to the extracted DC component, classifying the detected flicker visual sensitivity S(t) values from small to large, calculating the cumulative probability CPF(i) of each level of flicker visual sensitivity S(t), and calculating the short-time flicker value P according to the cumulative probability st as the obtained voltage flicker detection result.

[0082] ​​In this embodiment, the bandwidth of the band-pass filter in step S201 is 0.05 Hz to 35 Hz for filtering out direct current and components above the second harmonic and retaining , and the band-pass filter used in the band-pass filtering is composed of a first-order high-pass filter with a cutoff frequency of 0.05 Hz and a low-pass filter with a cutoff frequency of 35 Hz, wherein the transfer function of the first-order high-pass filter is:

[0083] ,

[0084] In the above formula, represents the transfer function of the first-order high-pass filter, is the Laplace operator, is the cutoff angular frequency of the high-pass filter, and in this embodiment When the sampling rate Fs=400 Hz, the Z transform of the first-order high-pass filter is:

[0085] ,

[0086] In the above formula, z is the independent variable.

[0087] In this embodiment, the low-pass filter is a 6th-order Butterworth filter, and its transfer function is:

[0088] ,

[0089] In the above formula, represents the transfer function of the low-pass filter, is the parameter of the i-th order Butterworth filter, is the Laplace operator, is the cutoff angular frequency of the low-pass filter. In this embodiment, , , , , , , .

[0090] When the sampling rate Fs=400 Hz, the Z transform of the low-pass filter is:

[0091] ,

[0092] wherein, , , , , , , , , , , , , , indicates the weight of each item.

[0093] In this embodiment, the transfer function of the visibility weighting filter in step S202 is:

[0094] ,

[0095] In the above equation, indicates the transfer function of the visibility weighting filter, is a parameter, is the Laplace operator, is a parameter, , , , is a parameter. In this embodiment, , , , , , In this embodiment, in order to simulate the response of the human eye to voltage fluctuations of different frequencies, the center frequency of the visibility weighting filter is 8.8 Hz. Assuming the sampling rate Fs=400 Hz, the Z transform of this weighting filter is:

[0096] ,

[0097] In the above equation, , , , , , , , , indicates the weight of each item.

[0098] In this embodiment, the function expression for calculating the square of the signal obtained after visibility weighting in step S203 is:

[0099] ,

[0100] In the above equation, indicates the visibility weighting squared signal, is the amplitude of the amplitude modulation wave voltage, is the amplitude of the power carrier voltage, is the angular frequency of the amplitude modulation wave voltage, is time, where the DC component is required for flicker evaluation.

[0101] The first-order low-pass filter in step S204 aims to extract the DC component of the output in the sixth step. The transfer function of the first-order low-pass filter in step S204 in the embodiment is:

[0102] ,

[0103] In the above formula, represents the transfer function of the first-order low-pass filter, is the Laplace operator, n is a parameter; in the embodiment, the cut-off frequency of the first-order low-pass filter is set to 0.53 Hz, and the time constant is 300 ms. The transfer function of the first-order low-pass filter can be expressed as:

[0104] ,

[0105] Suppose the sampling rate Fs=400 Hz, and the Z transform of the first-order low-pass filter is:

[0106] .

[0107] In step S205, the flicker visual sensitivity S(t) is calculated according to the extracted DC component. The flicker visual sensitivity S(t) is obtained by multiplying the extracted DC component by The detected flicker visual sensitivity S(t) is ranked from small to large, and there are usually not less than 64 levels.

[0108] In the embodiment, the function expression for calculating the cumulative probability CPF(i) of each level of flicker visual sensitivity S(t) is:

[0109] ,

[0110] In the above formula, represents the cumulative probability of the i-th level of flicker visual sensitivity S(t), is the cumulative time exceeding the i-th level of flicker visual sensitivity S(t), is the total test time;

[0111] The function expression for calculating the short-time flicker value P st according to the cumulative probability is:

[0112] ,

[0113] In the above formula, is the short-time flicker value, , , , and are the cumulative probabilities exceeding the preset threshold in the detection time of the specified duration, respectively. ,​ , and flicker perceptibility S(t). For example, as an optional embodiment, the flicker perceptibility value exceeding 0.1%, 1%, 3%, 10%, 50% is taken respectively in the embodiment.

[0114] Figure 2 For comparison between directly performing 0.05Hz high-pass filtering and performing 0.05Hz high-pass filtering after removing the direct current bias of the voltage square signal, the abscissa of the graph is the waveform signal, and the ordinate is the time, which indicates that the waveform signal is sampled in sequence according to the sampling frequency in the time window. Referring to Figure 2 It can be seen that, as the traditional method (without steps S102 and S103), when performing S104, the 0.05Hz high-pass filter link, after squaring the sampled data, it takes 11 seconds to converge to valid data, that is, the data before 11 seconds is too large and is invalid data, resulting in few available points, and the calculated short-time flicker value P st is 1.05; and after adding the direct current removal link of S102 and S103 in the embodiment method (represented as the present method in the graph), it converges in about 0.1S, that is, the data is stable in about 0.1 second, which increases the valid data for calculation, and the calculated short-time flicker value P st is 1.01. The short-time flicker value P st of the standard flicker is 1. It can be seen that, by steps S102 and S103, the voltage flicker acceleration detection method of the embodiment can effectively accelerate the convergence speed of the band-pass filter, solve the problem of slow demodulation filtering convergence speed and affecting the accuracy of flicker detection in the current IEC flicker detection method, and improve the detection accuracy while ensuring the flicker detection speed.

[0115] In addition, the embodiment also provides a voltage flicker acceleration detection system, which comprises a microprocessor and a memory connected to each other, and the microprocessor is programmed or configured to execute the voltage flicker acceleration detection method. In addition, the embodiment also provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program is used to program or configure the microprocessor to execute the voltage flicker acceleration detection method.

[0116] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-readable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0117] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A voltage flicker acceleration detection method, characterized by, Comprise: S101, square the voltage signal to be detected to obtain a voltage square signal; S102, obtain the DC bias of the voltage square signal; S103, subtract the DC bias of the voltage square signal from the voltage square signal to obtain an optimized voltage signal; S104, perform demodulation filtering, visual sensitivity weighting filtering, squaring, smoothing weighting filtering and statistical processing on the optimized voltage signal to obtain a voltage flicker detection result; Step S104 comprises: S201, remove DC and components above the second harmonic through band-pass filtering on the optimized voltage signal; S202, perform visual sensitivity weighting filtering using a visual sensitivity weighting filter; S203, square the signal obtained after visual sensitivity weighting filtering to obtain a visual sensitivity weighting filtering square signal; S204, extract the DC component of the visual sensitivity weighting filtering square signal using a first-order low-pass filter; S205, calculating the flicker perceptibility S(t) from the extracted direct current component, ranking the values of the obtained flicker perceptibility S(t) from small to large, calculating the cumulative probability CPF(i) of each ranked flicker perceptibility S(t), and calculating the short-time flicker value P from the cumulative probability st as the obtained voltage flicker detection result; The bandwidth of the band-pass filtering in step S201 is 0.05Hz-35Hz, and the band-pass filter used in the band-pass filtering is composed of a first-order high-pass filter with a cutoff frequency of 0.05Hz and a low-pass filter with a cutoff frequency of 35Hz, wherein the transfer function of the first-order high-pass filter is: , In the above formula, represents a transfer function of a first-order high-pass filter, is a Laplace operator, is a cut-off angular frequency of the high-pass filter; wherein the low-pass filter is a 6th order Butterworth filter, and the transfer function thereof is: , In the above formula, denotes the transfer function of a low-pass filter, are parameters of an i-th order Butterworth filter, is a Laplace operator, is a cut-off angular frequency of the low-pass filter; The transfer function of the visual sensitivity weighting filter in step S202 is: ， In the above formulae, denotes the transfer function of the visibility weighting filter, is a parameter, is the Laplacian operator, is a parameter, , , , is a parameter; The function expression for squaring the signal obtained after visual sensitivity weighting filtering in step S203 is: ， In the above formula, denotes the visibility-weighted filtered square signal, is the amplitude of the amplitude-modulated wave voltage, is the amplitude of the power frequency carrier voltage, is the angular frequency of the amplitude-modulated wave voltage, is the time; The transfer function of the first-order low-pass filter in step S204 is: ， In the above formulae, denotes the transfer function of a first-order low-pass filter, is the Laplace operator, n is a parameter; The flicker perceptibility S(t) in step S205 is calculated from the extracted direct current component, and means multiplying the extracted direct current component by The function expression of the cumulative probability CPF(i) of the flicker perceptibility S(t) of each level is obtained, and the function expression of the cumulative probability CPF(i) of the flicker perceptibility S(t) of each level is calculated as follows: ， In the above formula, denotes the cumulative probability of the i-th level of flicker visual sensitivity S(t), is the cumulative time exceeding the i-th level of flicker visual sensitivity S(t), is the total test time; the short-term flicker value P is calculated according to the cumulative probability st The functional expression is: ， In the above formula, is a short-time flicker value, , , , and is a flicker visual sensitivity S(t) that exceeds a preset threshold value , , , and cumulative probability in a specified time period.

2. The voltage flicker acceleration detection method of claim 1, wherein, The function expression of the voltage signal to be detected in step S101 is: ， In the above formulae, denotes the voltage signal to be detected at time t, is the amplitude of the power carrier voltage, is the amplitude of the amplitude-modulated voltage, is the angular frequency of the amplitude-modulated voltage, is the time, is the angular frequency of the power carrier voltage; denotes the fluctuating voltage.

3. The voltage flicker acceleration detection method of claim 1, wherein, The function expression for squaring the voltage signal to be detected to obtain a voltage square signal in step S101 is: ， in the above formulae, denotes the voltage square signal, is the amplitude of the power carrier voltage, is the amplitude of the amplitude modulation wave voltage, is the angular frequency of the amplitude modulation wave voltage, is the time, is the angular frequency of the power carrier voltage.

4. The voltage flicker acceleration detection method of claim 1, wherein, In step S102, the DC bias of the voltage square signal refers to the average value of the voltage square signal in the time window.

5. The voltage flicker acceleration detection method of claim 4, wherein, The function expression for obtaining the average value of the voltage square signal in the time window is: ， In the above formula, denotes the average value of the voltage squared signal over the time window, is the size of the time window, is the voltage squared signal.

6. The voltage flicker acceleration detection method of claim 1, wherein, The function expression for subtracting the DC bias of the voltage square signal from the voltage square signal to obtain an optimized voltage signal in step S103 is: ， In the above formulae, denotes the optimized voltage signal, is the voltage squared signal, denotes the average of the voltage squared signal over the time window.

7. A voltage flicker acceleration detection system comprising a microprocessor and a memory interconnected, characterized in that, The microprocessor is programmed or configured to perform the voltage flicker accelerated detection method of any one of claims 1-6.

8. A computer-readable storage medium having stored therein a computer program, characterized in that, The computer program is used to program or configure the microprocessor to perform the voltage flicker accelerated detection method of any one of claims 1-6.

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