Method and system for measuring equivalent capacitance of an ozone generator based on data fitting

Abstract

The application provides a DBD (Dielectric Barrier Discharge) type ozone generator parameter measurement method and system based on data fitting. Specifically, the method comprises the following steps: load voltage and current collection, virtual measurement of capacitor voltage, curve fitting, slope clustering, and DBD type ozone generator equivalent capacitor output. The method does not require the measurement circuit of the traditional scheme, and can automatically calculate the equivalent capacitor of the DBD type ozone generator through the program. The method not only has the advantages of strong applicability and accurate measurement results, but also solves the defects of the existing Lissajous figure method for obtaining the equivalent capacitor, such as long time consumption and low precision.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electrical parameter measurement, and particularly relates to a DBD type ozone generator equivalent capacitance measurement method and system. BACKGROUND

[0002] The equivalent capacitance of the DBD type ozone generator generally comprises a dielectric layer equivalent capacitance and a gas gap equivalent capacitance. In actual application, the measurement of the two parameters generally adopts a Lissajous figure method, that is, a Lissajous figure is formed through the end voltage of the ozone generator and the charge flowing through the generator, and the equivalent capacitance is calculated by using a related calculation formula.

[0003] In order to obtain the charge flowing through the generator, a test capacitor needs to be constructed, and the general method is to connect a measurement capacitor in series in the main circuit, which is tedious and dangerous in the test process. In addition to the above defects, the accuracy of the equivalent capacitance of the generator is highly dependent on the quality of the Lissajous figure, and the quality of the Lissajous figure is highly dependent on the performance of the components in the test system.

[0004] To solve this problem, the application provides a method for calculating the equivalent capacitance of a dielectric barrier discharge type ozone generator. Compared with the traditional calculation method, the method does not need to construct a special test system and does not need to rely on the quality of the Lissajous figure. The method not only greatly reduces the workload of the test process, but also directly avoids the measurement error caused by the low quality of the Lissajous figure. SUMMARY

[0005] The application provides a DBD (Dielectric Barrier Discharge) type ozone generator parameter measurement method based on data fitting. The method reconstructs the dielectric barrier load voltage and the virtual measurement capacitor voltage by collecting the dielectric barrier load voltage and the load current and by using a data fitting method. Based on the reconstructed data, the slope of the straight line formed by adjacent data points is calculated by using a difference algorithm, and the slopes are filtered and clustered. Based on the clustering result, the load equivalent capacitance value is calculated.

[0006] The DBD (Dielectric Barrier Discharge) type ozone generator parameter measurement method based on data fitting provided by the application comprises the following main steps:

[0007] The load voltage and the load current of the DBD type ozone generator during operation are collected, and the collected load voltage and load current data are stored;

[0008] harmonic analysis is performed on the stored load voltage to obtain a fundamental component and a main harmonic component of the load voltage;

[0009] integral operation is performed on the stored load current to obtain a virtual measurement capacitor voltage, and harmonic analysis is performed on the virtual measurement capacitor voltage to obtain a fundamental component and a main harmonic component of the virtual measurement capacitor voltage;

[0010] curve fitting is performed on the load voltage and the virtual measurement capacitor voltage according to the fundamental components and the main harmonic components of the load voltage and the virtual measurement capacitor voltage, and the load voltage and the virtual measurement capacitor voltage are reconstructed according to an expression of the fitting;

[0011] coordinate points are constructed using values of the reconstructed load voltage and virtual measurement capacitor voltage at corresponding sampling time points, a slope of adjacent coordinate points is calculated, cluster clustering is performed on the slope with a cluster number of 2, and a centroid value of a cluster is obtained;

[0012] The equivalent capacitance of the DBD ozone generator is calculated according to the centroid value of the cluster.

[0013] Further, the step of "collecting the load voltage and the load current of the DBD ozone generator during operation, and storing the collected load voltage and load current data" includes the following requirements:

[0014] The load voltage can be obtained using voltage collection schemes such as resistance voltage division, voltage transformers, and high-voltage probes, and the load current collection can be obtained using current collection schemes such as current transformers and current probes;

[0015] The frequency of data collection should not be lower than 100 times the working frequency of the DBD load generator;

[0016] The length of time for storing data should not be less than two complete working periods of the DBD load generator.

[0017] Further, the step of "performing integral operation on the stored load current to obtain a virtual measurement capacitor voltage, and performing harmonic analysis on the virtual measurement capacitor voltage to obtain a main harmonic component of the virtual measurement capacitor voltage" includes the following requirements:

[0018] The integral operation expression is: where V cm is the virtual measurement capacitor voltage, i DBD is the load current, T s is the time interval of data collection, which is the inverse of the frequency of data collection, k is the kth value in the sampling sequence, and ∑ is the summation symbol.

[0019] Furthermore, the step of "performing curve fitting of the load voltage and the virtual measured capacitor voltage based on the harmonic components of the load voltage and the virtual measured capacitor voltage, and reconstructing the load voltage and the virtual measured capacitor voltage based on the fitted expression" includes the following requirements:

[0020] The fitted expression is composed of sine and cosine waves of different frequencies;

[0021] The curve fitting is achieved by adjusting the amplitude and phase of the sine and cosine waves;

[0022] Furthermore, the steps of "constructing coordinate points using the reconstructed load voltage and virtual measured capacitor voltage at the corresponding sampling time, calculating the slope of adjacent coordinate points, performing clustering of the slopes with a cluster size of 2, and obtaining the centroid values ​​of the clusters" include the following requirements:

[0023] The expression for the coordinate points is [V r_DBD (k),V r_cm (k)], where V r_DBD For the reconstructed load voltage, V r_cm Let k be the reconstructed virtual measured capacitor voltage, and k be the kth value among the reconstructed load voltage and the reconstructed virtual measured capacitor voltage.

[0024] The slope calculation expression is as follows:

[0025] l(k)=(V r_cm (k+1)-V r_cm (k)) / (V r_DBD (k+1)-V r_DBD (k)), where l is the value of (k)).

[0026] The slope of adjacent coordinate points, k+1 is the (k+1)th value in the reconstructed load voltage and the reconstructed virtual measured capacitor voltage;

[0027] Furthermore, the step of "calculating the equivalent capacitance of the DBD type ozone generator based on the centroid value of the cluster" includes the following requirements:

[0028] The equivalent capacitance includes the blocking dielectric capacitance and the air gap capacitance of the DBD type ozone generator, and is calculated as: C d =K1, C p =K2, C g =C d C p / (C d -C p ), where C dC is the capacitance of the blocking medium p C is the series value of the capacitance of the blocking medium and the air gap g K1 and K2 are two centroid values of the cluster;

[0029] In addition, the application also provides a DBD type ozone generator equivalent capacitance measurement system based on data fitting, comprising the following modules:

[0030] The data acquisition module is used for acquiring the load voltage and the load current;

[0031] The virtual measurement capacitance voltage construction module is used for constructing a virtual measurement capacitance voltage through the load current;

[0032] The harmonic analysis module is used for analyzing the fundamental wave component and the main harmonic component of the load voltage and the virtual measurement capacitance voltage;

[0033] The voltage reconstruction module is used for reconstructing the load voltage and the virtual measurement capacitance voltage;

[0034] The slope clustering module is used for calculating the slope of adjacent coordinate points, obtaining the centroid of the slope clustering cluster, and implementing equivalent capacitance measurement by using the foregoing method.

[0035] Advantages:

[0036] The application provides a DBD (Dielectric Barrier Discharge) type ozone generator parameter measurement method and system based on data fitting. Specifically, the method comprises the following steps: load voltage and current acquisition, measurement capacitance voltage virtualization, curve fitting, slope clustering and DBD type ozone generator equivalent capacitance output. The method does not require a measurement circuit of a traditional scheme, and can automatically calculate the equivalent capacitance of the DBD type ozone generator through a program. The method not only has the advantages of strong applicability and accurate measurement results, but also solves the defects of long time consumption and low precision of an existing Lissajous figure method for obtaining the equivalent capacitance. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a measurement method flowchart;

[0038] Figure 2 It is a commonly used DBD type ozone generator Lissajous figure measurement system;

[0039] Figure 3 It is a Lissajous figure of a DBD type ozone generator;

[0040] Figure 4 It is a load voltage fitting effect diagram;

[0041] Figure 5The Lissajous figures obtained by the two methods are compared. DETAILED DESCRIPTION

[0042] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the present application can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present application. The measurement method flow of the present application is shown in the following figure, which will be discussed in detail below. Figure 1

[0043] The DBD (Dielectric Barrier Discharge) type ozone generator parameter measurement method based on data fitting proposed by the present application is composed of the following main steps:

[0044] The load voltage and load current of the DBD type ozone generator during operation are collected, and the collected load voltage and load current data are stored;

[0045] The stored load voltage is subjected to harmonic analysis to obtain the fundamental component and main harmonic component of the load voltage;

[0046] The stored load current is subjected to integral operation to obtain a virtual measurement capacitor voltage, and the virtual measurement capacitor voltage is subjected to harmonic analysis to obtain the fundamental component and main harmonic component of the virtual measurement capacitor voltage;

[0047] The load voltage and the virtual measurement capacitor voltage are subjected to curve fitting according to the fundamental component and main harmonic component of the load voltage and the virtual measurement capacitor voltage, and the load voltage and the virtual measurement capacitor voltage are reconstructed according to the fitted expression;

[0048] The values of the reconstructed load voltage and virtual measurement capacitor voltage at the corresponding sampling time are used to construct coordinate points, the slopes of adjacent coordinate points are calculated, the slopes are clustered into clusters with a number of 2, and the centroid values of the clusters are obtained;

[0049] The equivalent capacitance of the DBD type ozone generator is calculated according to the centroid values of the clusters.

[0050] Further, the step of "collecting the load voltage and load current of the DBD type ozone generator during operation, and storing the collected load voltage and load current data" includes the following requirements:

[0051] ​The load voltage can be obtained by voltage acquisition schemes such as resistance voltage division, voltage transformer, and high-voltage probe, and the load current acquisition can be obtained by current acquisition schemes such as current transformer and current probe;

[0052] The frequency of data acquisition should not be lower than 100 times of the working frequency of the DBD type load generator;

[0053] The length of time for storing data should not be lower than two complete working periods of the DBD type load generator.

[0054] Further, the step of "integrating the stored load current to obtain a virtual measurement capacitor voltage, and performing harmonic analysis on the virtual measurement capacitor voltage to obtain the main harmonic component of the virtual measurement capacitor voltage" includes the following requirements:

[0055] The integral expression is: In the formula, V cm is the virtual measurement capacitor voltage, i DBD is the load current, T s is the time interval of data acquisition, that is, the inverse of the frequency of data acquisition, k is the kth value in the sampling sequence, and ∑ is the summation symbol;

[0056] Further, the step of "curve fitting the load voltage and the virtual measurement capacitor voltage according to the harmonic components of the load voltage and the virtual measurement capacitor voltage, and reconstructing the load voltage and the virtual measurement capacitor voltage according to the fitted expression" includes the following requirements:

[0057] The fitted expression is composed of sine waves and cosine waves of different frequencies;

[0058] The curve fitting is achieved by adjusting the amplitudes and phases of the sine waves and cosine waves;

[0059] Further, the step of "constructing coordinate points with the numerical values of the reconstructed load voltage and virtual measurement capacitor voltage at the corresponding sampling time, calculating the slope of adjacent coordinate points, clustering the slopes in clusters with a number of 2, and obtaining the centroid values of the clusters" includes the following requirements:

[0060] The expression of the coordinate points is [V r_DBD (k), V r_cm (k)], where V r_DBD is the reconstructed load voltage, V r_cm is the reconstructed virtual measurement capacitor voltage, and k is the kth value in the reconstructed load voltage and the reconstructed virtual measurement capacitor voltage;

[0061] The slope calculation expression is as follows:

[0062] l(k)=(V r_cm (k+1)-V r_cm (k)) / (V r_DBD (k+1)-V r_DBD (k)), where l is the value of (k)).

[0063] The slope of adjacent coordinate points, k+1 is the (k+1)th value in the reconstructed load voltage and the reconstructed virtual measured capacitor voltage;

[0064] Furthermore, the step of "calculating the equivalent capacitance of the DBD type ozone generator based on the centroid value of the cluster" includes the following requirements:

[0065] The equivalent capacitance includes the blocking dielectric capacitance and the air gap capacitance of the DBD type ozone generator, and is calculated as: C d =K1, C p =K2, C g =C d C p / (C d -C p ), where C d For the blocking dielectric capacitor, C p The series value of the barrier dielectric capacitance and the air gap capacitance, C g K1 and K2 are the two centroid values ​​of the cluster, where K1 and K2 are the air gap capacitances.

[0066] Furthermore, this invention also provides a DBD-type ozone generator equivalent capacitance measurement system based on data fitting, comprising the following modules:

[0067] Data acquisition module: used to acquire the load voltage and load current;

[0068] Virtual capacitor voltage measurement construction module: used to construct a virtual capacitor voltage measurement using the load current;

[0069] Harmonic analysis module: used to analyze the fundamental and major harmonic components of the load voltage and the virtual measured capacitor voltage;

[0070] Voltage reconstruction module: used to reconstruct the load voltage and the virtual measured capacitor voltage;

[0071] Slope clustering module: used to calculate the slope of adjacent coordinate points and obtain the centroid of slope clusters;

[0072] Specifically, step 1: select appropriate voltage and current measuring elements according to the working voltage and working current of the DBD ozone generator, such as selecting a voltage probe with a withstand voltage of 10kV and a current probe with a rated current of 10A;

[0073] Step 2: set an appropriate sampling frequency, considering that the working frequency of the DBD ozone generator is generally several kilohertz, therefore, the voltage probe and the current probe can be directly connected to an oscilloscope, and the high sampling frequency of the oscilloscope can be used to obtain appropriate data, for example, an oscilloscope with a sampling rate of 100 megahertz is selected as a data acquisition and data storage element;

[0074] Step 3: import the stored data in the oscilloscope into a mathematical analysis tool (such as matlab) to analyze the harmonic composition in the working voltage and working current of the DBD ozone generator;

[0075] Step 4: perform discrete integral operation on the working current of the DBD ozone generator to obtain a virtual measurement capacitor voltage;

[0076] Step 5: according to the harmonic composition characteristics obtained in step 3, use the relevant mathematical analysis tool to adjust the amplitude and phase of each sine wave and cosine wave, so that the fitting result of the load voltage and the virtual measurement capacitor voltage is as close as possible to the sampling result. Figure 4 The load voltage fitting result under a set of measurement data is given;

[0077] Step 6: reconstruct the load voltage and the virtual measurement capacitor voltage according to the fitting function and the original sampling time interval, and form a data set;

[0078] Step 7: use the difference method to calculate the slope of adjacent two data points, and form a slope storage array, the calculation formula is:

[0079] k = (y[n+1]-y[n]) / (x[n+1]-x[n])

[0080] Where (x[n], y[n]) and (x[n+1], y[n+1]) are the horizontal and vertical coordinates of the adjacent two data points. Step 8: use K-means clustering method to cluster the slope storage array calculated in step 7, get the two most accurate ranges of the slope, and calculate the centroid value of the clustering result based on this;

[0081] Step 9: use the calculation expression: d C p = K1, C g = K2, C d C p / (C d -C p) to calculate the equivalent capacitance value of the DBD ozone generator. Wherein, C d is the blocking medium capacitance, C p is the blocking medium capacitance and air gap capacitance series value, C g is the air gap capacitance, K1 and K2 are the two centroid values of the cluster.

Claims

1. A method of measuring the equivalent capacitance of an ozone generator based on data fitting, The method is characterized in that the following steps are included: The load voltage and the load current of the DBD ozone generator during operation are collected, and the collected load voltage and load current data are stored; The stored load voltage is subjected to harmonic analysis to obtain the fundamental component and the main harmonic component of the load voltage; The stored load current is subjected to integral operation to obtain a virtual measurement capacitor voltage, and the virtual measurement capacitor voltage is subjected to harmonic analysis to obtain the fundamental component and the main harmonic component of the virtual measurement capacitor voltage; The load voltage and the virtual measurement capacitor voltage are subjected to curve fitting according to the fundamental component and the main harmonic component of the load voltage and the virtual measurement capacitor voltage, and the load voltage and the virtual measurement capacitor voltage are reconstructed according to the fitted expression; Coordinate points are constructed by using the values of the reconstructed load voltage and virtual measurement capacitor voltage at corresponding sampling time points, the slope of adjacent coordinate points is calculated, the slopes are clustered into clusters with a number of 2, and the centroid values of the clusters are obtained; The equivalent capacitor of the DBD ozone generator is calculated according to the centroid values of the clusters; The step of "collecting the load voltage and the load current of the DBD ozone generator during operation, and storing the collected load voltage and load current data" includes the following requirements: The load voltage is obtained by using a resistance voltage division, a voltage transformer or a high-voltage probe voltage collection scheme, and the load current is obtained by using a current transformer or a current probe current collection scheme; The frequency of data collection should not be lower than 100 times the working frequency of the DBD ozone generator; The length of time for storing data should not be lower than two complete working periods of the DBD ozone generator; The step of "subjecting the stored load current to integral operation to obtain a virtual measurement capacitor voltage, and subjecting the virtual measurement capacitor voltage to harmonic analysis to obtain the main harmonic component of the virtual measurement capacitor voltage" includes the following requirements: The integral operation expression is: wherein is the virtual measurement capacitance voltage, is the load current, is the time interval of data acquisition, i.e. the inverse of the frequency data acquisition, is the value of the sample sequence, is the value of the sample sequence, is the summation symbol; The step of "subjecting the load voltage and the virtual measurement capacitor voltage to curve fitting according to the harmonic components of the load voltage and the virtual measurement capacitor voltage, and reconstructing the load voltage and the virtual measurement capacitor voltage according to the fitted expression" includes the following requirements: The fitted expression is composed of sine waves and cosine waves with different frequencies; The curve fitting is realized by adjusting the amplitudes and phases of the sine waves and cosine waves; The step of "constructing coordinate points by using the values of the reconstructed load voltage and virtual measurement capacitor voltage at corresponding sampling time points, calculating the slope of adjacent coordinate points, clustering the slopes into clusters with a number of 2, and obtaining the centroid values of the clusters" includes the following requirements: The expression of the coordinate point is wherein, is the reconstructed load voltage, is the reconstructed virtual measurement capacitor voltage, is the first value of the reconstructed load voltage and the reconstructed virtual measurement capacitor voltage; The slope calculation expression is: wherein is the slope of the adjacent coordinate point, is the i-th value of the reconstructed load voltage and the reconstructed virtual measurement capacitor voltage, is the i-th value of the reconstructed load voltage and the reconstructed virtual measurement capacitor voltage, The step of "calculating the equivalent capacitor of the DBD ozone generator according to the centroid values of the clusters" includes the following requirements: The equivalent capacitance includes, a blocking dielectric capacitance and an air gap capacitance of the DBD type ozone generator, calculated as: , , wherein, is the blocking dielectric capacitance, is the blocking dielectric capacitance and air gap capacitance in series, is the air gap capacitance, and are the two barycentric values of the cluster.

2. A data fit based measurement system for equivalent capacitance of an ozone generator, comprising: The method for measuring the equivalent capacitor is implemented by using the method of claim 1, including the following modules: A data collection module for collecting the load voltage and the load current; a virtual measurement capacitor voltage construction module, configured to construct a virtual measurement capacitor voltage by the load current; a harmonic analysis module, configured to analyze fundamental wave components and main harmonic components of the load voltage and the virtual measurement capacitor voltage; a voltage reconstruction module, configured to reconstruct the load voltage and the virtual measurement capacitor voltage; a slope clustering module, configured to calculate slopes of adjacent coordinate points, and obtain a centroid of a slope clustering cluster.

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