Method and system for calculating a corrected secondary winding output harmonic voltage signal

Abstract

The application discloses a method and system for calculating a corrected secondary winding output harmonic voltage signal. The method comprises: calculating the equivalent resistance R C , the equivalent capacitive reactance X C‑h and the equivalent impedance value Z C‑h of a high-voltage capacitor C1 and a medium-voltage capacitor C2 in parallel at each harmonic; measuring the input impedance of an electromagnetic unit, combining the equivalent impedance value Z C‑h , and calculating a capacitor correction coefficient K 1‑h at each harmonic frequency; measuring the frequency response characteristic of the electromagnetic unit, and calculating an electromagnetic correction coefficient K 2‑h at each harmonic frequency; according to the capacitor correction coefficient K 1‑h and the electromagnetic correction coefficient K 2‑h , calculating a secondary winding measurement voltage correction coefficient K h at each harmonic frequency; Fourier decomposing a secondary winding output voltage signal U2 to obtain a harmonic component U 2H , and correcting the harmonic component U h according to the voltage correction coefficient K 2H to determine a corrected secondary winding output harmonic voltage signal U 2Hd .

Description

Technical Field

[0001] This invention relates to the field of high-voltage insulation equipment technology, and more specifically, to a method and system for calculating the corrected secondary winding output harmonic voltage signal. Background Technology

[0002] Accurate monitoring of power quality is fundamental to comprehensively understanding and controlling various power quality indicators of the power grid, addressing issues such as voltage and harmonic exceedances, and quantifying the tolerance of equipment to power quality impacts. Currently, most countries and regions use electromagnetic transformers for power quality measurement. This approach is feasible for low- and medium-voltage systems, but for high- and ultra-high-voltage systems, where capacitive voltage transformers (CVTs) are mostly used and designed based on power frequency conditions, significant errors often occur when using them to measure harmonics, transients, and other non-power frequency signals in the power grid. Therefore, based on the premise that CVTs remain linear circuits in the harmonic frequency band, it is necessary to correct the harmonic measurement voltage of CVTs to improve their measurement accuracy and meet the accuracy requirements of power quality monitoring systems for data sources.

[0003] Currently, the common practice is to obtain the frequency response curve of a CVT through offline analysis combined with actual measurements, and then calculate the harmonic voltage correction coefficient for each harmonic. This correction coefficient is then used to correct the CVT's secondary voltage during on-site testing. The main methods for testing the broadband transfer characteristics of a CVT include the frequency sweep method, pulse measurement method, scattering parameter method, and high-voltage harmonic method. Due to equipment limitations, the first three methods apply low voltage and weak signals to the CVT. Although they have wide measurement bandwidths, the test results are easily affected by external interference and fluctuate significantly, failing to accurately reflect the broadband transfer characteristics of the CVT under high voltage. The high-voltage harmonic method applies a series of harmonics to the primary side of the CVT using a high-voltage harmonic source, and obtains the broadband transfer characteristics of the CVT by measuring the voltages on both the primary and secondary sides. While this method can accurately test the broadband transfer characteristics of the CVT, it places extremely high demands on the capacity of the harmonic source: for high-voltage products, applying a high-frequency, high-amplitude primary power supply, even with a single-frequency harmonic source, is extremely difficult. Furthermore, as the voltage level of the product increases, the development difficulty and cost of the harmonic source will become even greater. Furthermore, the frequency response curves of CVTs from different manufacturers and models may vary or differ, requiring individual testing, which results in a huge workload and is uneconomical. Summary of the Invention

[0004] According to the present invention, a method and system for calculating the corrected secondary winding output harmonic voltage signal are provided to solve the problem that there are still certain shortcomings in the existing CVT harmonic voltage correction technology.

[0005] According to a first aspect of the present invention, a method for calculating a corrected secondary winding output harmonic voltage signal is provided, comprising:

[0006] Calculate the equivalent resistance R of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic. C Equivalent capacitive X C-h and equivalent impedance value Z C-h ;

[0007] Measure the input impedance of the electromagnetic unit, and combine it with the equivalent impedance value Z. C-h Calculate the capacitance correction factor K at each harmonic frequency. 1-h ;

[0008] Measure the frequency response characteristics of the electromagnetic unit and calculate the electromagnetic correction coefficient K at each harmonic frequency. 2-h ;

[0009] According to the capacitance correction coefficient K 1-h and the electromagnetic correction coefficient K 2-h Calculate the correction factor K for the measured voltage of the secondary winding at each harmonic frequency. h ;

[0010] Fourier decomposition of the output voltage signal U2 across the secondary winding yields the harmonic components U. 2H And according to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd .

[0011] Optionally, calculate the equivalent resistance R of the parallel connection of the high-voltage capacitor C1 and the medium-voltage capacitor C2 under each harmonic. C Equivalent capacitive X C-h and equivalent impedance value Z C-h ,include:

[0012] Calculate the equivalent resistance R of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C :

[0013]

[0014] Calculate the equivalent capacitive reactance X of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h :

[0015]

[0016] Calculate the equivalent impedance Z of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h :

[0017] Z C-h =R C -jX C-h

[0018] In the formula, h is the harmonic order; ω h =2πhf N f is the h-th harmonic angular frequency. N The power frequency is ω. N C N K is the rated capacitor of the voltage divider. CN tanδ is the rated voltage division ratio of the voltage divider. C This is the tangent of the voltage divider loss angle.

[0019] Optionally, the input impedance of the electromagnetic unit is measured, combined with the equivalent impedance value Z. C-h Calculate the capacitance correction factor K at each harmonic frequency. 1-h ,include:

[0020] Calculate the capacitance correction coefficient K at each harmonic frequency using the following formula. 1-h :

[0021]

[0022] In the formula, Z T-h This is the measured input impedance value of the electromagnetic unit under the h-th harmonic.

[0023] Optionally, the frequency response characteristics of the electromagnetic unit are measured, and the electromagnetic correction coefficient K at each harmonic frequency is calculated. 2-h ,include:

[0024] Calculate the electromagnetic correction coefficient K at each harmonic frequency using the following formula. 2-h :

[0025]

[0026] In the formula, K MN The rated voltage ratio of the intermediate transformer; H T (jω h ) represents the frequency response measurement value of the electromagnetic unit under the h-th harmonic.

[0027] Optionally, based on the capacitance correction coefficient K 1-h and the electromagnetic correction coefficient K 2-h Calculate the correction factor K for the measured voltage of the secondary winding at each harmonic frequency. h ,include;

[0028] Calculate the correction factor K for the secondary winding measured voltage at each harmonic frequency using the following formula. h Kh =K 1-h K 2-h .

[0029] Optionally, the Fourier decomposition of the output voltage signal U2 across the secondary winding yields the harmonic components U. 2H And according to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd ,include:

[0030] According to the following formula, the Fourier decomposition of the output voltage signal U2 across the secondary winding yields the harmonic component U. 2H :

[0031]

[0032] According to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd :

[0033]

[0034] In the formula, U 2-h and θ 2-h , respectively, are the effective value and phase angle of the h-th harmonic component of signal U2; n is the highest harmonic order of interest.

[0035] According to another aspect of the present invention, a system for calculating a corrected secondary winding output harmonic voltage signal is also provided, comprising:

[0036] The equivalent parameter calculation module is used to calculate the equivalent resistance R of the parallel connection of the high-voltage capacitor C1 and the medium-voltage capacitor C2 under each harmonic. C Equivalent capacitive X C-h and equivalent impedance value Z C-h ;

[0037] The capacitance correction factor calculation module is used to measure the input impedance of the electromagnetic unit, combined with the equivalent impedance value Z. C-h Calculate the capacitance correction factor K at each harmonic frequency. 1-h ;

[0038] The electromagnetic correction coefficient calculation module is used to measure the frequency response characteristics of the electromagnetic unit and calculate the electromagnetic correction coefficient K at each harmonic frequency. 2-h ;

[0039] The voltage correction factor calculation module is used to calculate the voltage correction factor K based on the capacitance correction factor K. 1-h and the electromagnetic correction coefficient K2-h Calculate the correction factor K for the measured voltage of the secondary winding at each harmonic frequency. h ;

[0040] The module for correcting harmonic voltage signals is used to perform Fourier decomposition of the output voltage signal U2 across the secondary winding to obtain the harmonic components U. 2H And according to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd .

[0041] Optionally, the module for calculating equivalent parameters includes:

[0042] The equivalent resistance calculation submodule is used to calculate the equivalent resistance R of the parallel connection of the high-voltage capacitor C1 and the medium-voltage capacitor C2 under each harmonic according to the following formula. C :

[0043]

[0044] The equivalent capacitive reactance calculation submodule is used to calculate the equivalent capacitive reactance X of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h :

[0045]

[0046] The equivalent impedance calculation submodule is used to calculate the equivalent impedance Z of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h :

[0047] Z C-h =R C -jX C-h

[0048] In the formula, h is the harmonic order; ω h =2πhf N f is the h-th harmonic angular frequency. N The power frequency is ω. N C N K is the rated capacitor of the voltage divider. CN tanδ is the rated voltage division ratio of the voltage divider. C This is the tangent of the voltage divider loss angle.

[0049] Optionally, the module for calculating the capacitance correction factor includes:

[0050] The capacitor correction factor calculation submodule calculates the capacitor correction factor K at each harmonic frequency according to the following formula. 1-h :

[0051]

[0052] In the formula, Z T-h This is the measured input impedance value of the electromagnetic unit under the h-th harmonic.

[0053] Optionally, the module for calculating electromagnetic correction coefficients includes:

[0054] The electromagnetic correction coefficient calculation submodule is used to calculate the electromagnetic correction coefficient K at each harmonic frequency according to the following formula. 2-h :

[0055]

[0056] In the formula, K MN The rated voltage ratio of the intermediate transformer; H T (jω h ) represents the frequency response measurement value of the electromagnetic unit under the h-th harmonic.

[0057] Optionally, the voltage correction factor calculation module includes:

[0058] The voltage correction factor calculation submodule is used to calculate the secondary winding measurement voltage correction factor K at each harmonic frequency according to the following formula. h ,

[0059] K h =K 1-h K 2-h

[0060] Optionally, a harmonic voltage signal correction module is defined, including:

[0061] The harmonic component submodule is used to Fourier decompose the output voltage signal U2 across the secondary winding according to the following formula, and obtain the harmonic component U. 2H :

[0062]

[0063] The submodule for determining the corrected harmonic voltage signal is used to determine the voltage correction coefficient K. h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd :

[0064]

[0065] In the formula, U 2-h and θ 2-h , respectively, are the effective value and phase angle of the h-th harmonic component of signal U2; n is the highest harmonic order of interest.

[0066] Therefore, by measuring the input impedance and frequency response characteristics of the electromagnetic unit, the harmonic voltage correction coefficient can be obtained, solving the problems of high experimental difficulty and large measurement error in the existing technology of obtaining the harmonic voltage correction coefficient by directly measuring the frequency response characteristics of CVT. This method has no impact on the product itself and has the advantages of simple operation and good economy, which is conducive to its widespread application. Attached Figure Description

[0067] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0068] Figure 1 This is a schematic diagram of a method for calculating the corrected secondary winding output harmonic voltage signal according to this embodiment;

[0069] Figure 2 This is a schematic diagram of the CVT equivalent circuit model described in this embodiment;

[0070] Figure 3 This is a schematic diagram of the components of a method for calculating the harmonic voltage correction coefficient of a capacitive voltage transformer as described in this embodiment.

[0071] Figure 4 This is a schematic diagram of the composition of the frequency response characteristic measurement module described in this embodiment;

[0072] Figure 5 This is a schematic diagram of the system for calculating and correcting the harmonic voltage signal output by the secondary winding as described in this embodiment.

[0073] In the diagram, 1-Impedance measurement module; 2-Frequency response characteristic measurement module; 3-Impedance value library; 4-Frequency response value library; 5-Harmonic voltage correction coefficient calculation module; 6-Arbitrary signal generator; 7-Power amplifier; 8-Electromagnetic unit; 9-Voltage ratio standard; 10-Frequency response analysis module. Detailed Implementation

[0074] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0075] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0076] According to a first aspect of the present invention, a method 100 for calculating a corrected secondary winding output harmonic voltage signal is provided, with reference to... Figure 1 As shown, the method 100 includes:

[0077] S101: Calculate the equivalent resistance R of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic. C Equivalent capacitive X C-h and equivalent impedance value Z C-h ;

[0078] S102: Measure the input impedance of the electromagnetic unit, and combine it with the equivalent impedance value Z. C-h Calculate the capacitance correction factor K at each harmonic frequency. 1-h ;

[0079] S103: Measure the frequency response characteristics of the electromagnetic unit and calculate the electromagnetic correction coefficient K at each harmonic frequency. 2-h ;

[0080] S104: According to the capacitance correction coefficient K 1-h and the electromagnetic correction coefficient K 2-h Calculate the correction factor K for the measured voltage of the secondary winding at each harmonic frequency. h ;

[0081] S105: Fourier decomposition of the output voltage signal U2 across the secondary winding yields the harmonic components U. 2H And according to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd .

[0082] Specifically, a CVT is a voltage transformer composed of a capacitive voltage divider and an electromagnetic unit. The capacitive voltage divider first divides the primary voltage to obtain a voltage of approximately 10-20kV. Then, the electromagnetic unit further reduces this voltage to 100 / √3V to supply protection and measurement devices. The capacitive voltage divider consists of a high-voltage capacitor C1 and a medium-voltage capacitor C2. The electromagnetic unit is connected in parallel across capacitor C2 and consists of an intermediate transformer, a compensating reactor, and a damping device. Analysis of the CVT's structural characteristics shows that its equivalent circuit can be considered a linear system across the entire harmonic frequency range. Using Thevenin's theorem, the equivalent circuit model of the CVT can be obtained as follows: Figure 2 As shown in the figure, Zc is the equivalent impedance of C1 and C2 in parallel, ZT is the equivalent impedance of the electromagnetic unit, U1 is the primary voltage, and U2 is the secondary voltage.

[0083] It can be seen that the overall transmission characteristics of the CVT are jointly determined by the parameters of each capacitor element and each component of the electromagnetic unit. The transfer function of the electromagnetic unit is defined as H. T If (s), then the overall transfer function H(s) of the CVT is:

[0084]

[0085] In the formula, K CN = (C1+C2) / C1 is the rated voltage division ratio of the voltage divider. According to the CVT product design methodology, once the voltage level and the rated primary voltage of the intermediate transformer are determined, the rated values ​​of the high- and medium-voltage capacitors of the voltage divider are basically fixed, i.e., K. CN This is a fixed value. Therefore, the harmonic transmission characteristics and resonant point location of the CVT mainly depend on the relevant parameters of the electromagnetic unit. By understanding the harmonic transmission characteristics of the electromagnetic unit, the overall harmonic transmission characteristics of the CVT can be determined. Under harmonic conditions, due to the combined effect of the stray capacitance of the electromagnetic unit and the inductance parameters of the coil, multiple series and parallel resonance modes exist in the circuit, causing the frequency response characteristics of the electromagnetic unit to exhibit severe nonlinearity. To obtain accurate harmonic measurement signals, it is necessary to obtain the harmonic measurement voltage correction coefficient to correct the secondary winding measurement voltage.

[0086] definition The above formula can then be simplified to:

[0087]

[0088] In the formula, K MN K represents the rated voltage ratio of the intermediate transformer. N =K CN K MN Let K be the rated voltage ratio of the CVT. Then the harmonic measurement voltage correction factor K can be obtained as:

[0089] K = K1K2

[0090] Technical approach: The input impedance characteristics of the electromagnetic unit are measured, and the correction coefficient K1 at each harmonic frequency is calculated by combining the impedance values ​​of the high-voltage capacitor C1 and the medium-voltage capacitor C2. The frequency response characteristics of the electromagnetic unit are measured to obtain the correction coefficient K2 at each harmonic frequency. Based on the correction coefficients K1 and K2, the correction coefficient K of the secondary winding measurement voltage at each harmonic frequency is calculated, thereby achieving the purpose of correcting the CVT harmonic measurement values. The specific calculation process is as follows:

[0091] Step 1: Calculate the equivalent resistance R of capacitors C1 and C2 in parallel under each harmonic. C Equivalent capacitive X C-h and equivalent impedance value Z C-h .

[0092]

[0093]

[0094] Z C-h =R C -jX C-h

[0095] In the formula, h is the harmonic order; ω h =2πhf N f is the h-th harmonic angular frequency. N The power frequency (angular frequency ω) N );C N K is the rated capacitor of the voltage divider. CN tanδ is the rated voltage division ratio of the voltage divider. C This is the tangent of the voltage divider loss angle.

[0096] Step 2: Calculate the correction factor K at each harmonic frequency. 1-h .

[0097]

[0098] In the formula, Z T-h This is the measured input impedance value of the electromagnetic unit under the h-th harmonic.

[0099] Step 3: Calculate the correction coefficient K2-h at each harmonic frequency.

[0100]

[0101] In the formula, K MN The rated voltage ratio of the intermediate transformer; H T (jω h ) represents the frequency response measurement value of the electromagnetic unit under the h-th harmonic.

[0102] Step 4: Calculate the correction factor K for the secondary winding measured voltage at each harmonic frequency. h .

[0103] K h =K 1-h K 2-h

[0104] Step 5: Fourier decomposition of the output voltage signal U2 across the secondary winding to obtain the harmonic components U 2H Calculate the corrected secondary winding output harmonic voltage signal U. 2Hd .

[0105]

[0106]

[0107] To achieve the above process, it is first necessary to measure the input impedance and frequency response of the electromagnetic unit at each harmonic frequency. Then, combined with the basic parameters of the CVT, the voltage correction coefficient for each harmonic can be calculated according to the above calculation process. In field applications, this correction coefficient is used to correct the harmonic measurement signal of the CVT's secondary winding to improve the accuracy of CVT harmonic signal measurement. Currently, the rated voltage of the electromagnetic unit is generally designed to be around 10-20kV. Assuming a harmonic voltage content of 20%, the harmonic voltage required for the frequency response characteristic test does not exceed 5kV. Compared with testing directly through the primary side of the transformer, the capacity of the harmonic voltage source can be greatly reduced in this case.

[0108] refer to Figure 3 and Figure 4 As shown, this invention obtains harmonic voltage correction coefficients by measuring the input impedance and frequency response characteristics of an electromagnetic unit, thereby achieving the purpose of correcting CVT harmonic measurement values. Its main structure includes: an impedance measurement module 1, a frequency response characteristic measurement module 2, an impedance value library 3, a frequency response value library 4, and a harmonic voltage correction coefficient calculation module 5.

[0109] Impedance measurement module 1 measures the input impedance value of the electromagnetic unit at each harmonic frequency and sends it to the electromagnetic unit impedance module of impedance database 3 for storage.

[0110] The frequency response measurement module 2 includes an arbitrary signal generator 6, a power amplifier 7, an electromagnetic unit 8, a voltage proportional standard 9, and a frequency response analysis module 10. The arbitrary signal generator 6 sequentially outputs single-harmonic voltages, which are then boosted to the required voltage amplitude by the power amplifier 7 and connected to the primary side of the electromagnetic unit 8 and the voltage proportional standard 9. The frequency response analysis module 10 collects the secondary voltages of the electromagnetic unit and the voltage proportional standard 9 to perform frequency response characteristic analysis, calculates the frequency response measurement values ​​of the electromagnetic unit under each harmonic, and stores them in the frequency response value library 4.

[0111] Impedance Database 3 includes a CVT basic parameter module, a voltage divider impedance module, and an electromagnetic unit impedance module. The CVT basic parameter module stores basic CVT parameters, including rated capacitance, rated voltage divider ratio, dielectric loss tangent, and rated voltage ratio of the intermediate transformer. The voltage divider impedance module calls the CVT basic parameter module to calculate the equivalent impedance of capacitors C1 and C2 in parallel at each harmonic frequency.

[0112] The harmonic voltage correction coefficient calculation module 5 calls the impedance value library 3 and the frequency response value library 4 to calculate the correction coefficient for the secondary winding measurement voltage at each harmonic frequency. This correction coefficient is used to correct the CVT's secondary winding harmonic measurement signal, improving the accuracy of CVT harmonic signal measurement for use in power quality monitoring terminals.

[0113] Optionally, calculate the equivalent resistance R of the parallel connection of the high-voltage capacitor C1 and the medium-voltage capacitor C2 under each harmonic. C Equivalent capacitive X C-h and equivalent impedance value Z C-h ,include:

[0114] Calculate the equivalent resistance R of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C :

[0115]

[0116] Calculate the equivalent capacitive reactance X of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h :

[0117]

[0118] Calculate the equivalent impedance Z of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h :

[0119] Z C-h =R C -jX C-h

[0120] In the formula, h is the harmonic order; ω h =2πhf N f is the h-th harmonic angular frequency. N The power frequency is ω. N C N K is the rated capacitor of the voltage divider. CN tanδ is the rated voltage division ratio of the voltage divider. C This is the tangent of the voltage divider loss angle.

[0121] Optionally, the input impedance of the electromagnetic unit is measured, combined with the equivalent impedance value Z. C-h Calculate the capacitance correction factor K at each harmonic frequency. 1-h ,include:

[0122] Calculate the capacitance correction coefficient K at each harmonic frequency using the following formula. 1-h :

[0123]

[0124] In the formula, Z T-h This is the measured input impedance value of the electromagnetic unit under the h-th harmonic.

[0125] Optionally, the frequency response characteristics of the electromagnetic unit are measured, and the electromagnetic correction coefficient K at each harmonic frequency is calculated. 2-h ,include:

[0126] Calculate the electromagnetic correction coefficient K at each harmonic frequency using the following formula. 2-h :

[0127]

[0128] In the formula, K MN The rated voltage ratio of the intermediate transformer; H T (jω h ) represents the frequency response measurement value of the electromagnetic unit under the h-th harmonic.

[0129] Optionally, based on the capacitance correction coefficient K 1-h and the electromagnetic correction coefficient K 2-h Calculate the correction factor K for the measured voltage of the secondary winding at each harmonic frequency. h ,include;

[0130] Calculate the correction factor K for the secondary winding measured voltage at each harmonic frequency using the following formula. h K h =K 1-h K 2-h .

[0131] Optionally, the Fourier decomposition of the output voltage signal U2 across the secondary winding yields the harmonic components U. 2H And according to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd ,include:

[0132] According to the following formula, the Fourier decomposition of the output voltage signal U2 across the secondary winding yields the harmonic component U. 2H :

[0133]

[0134] According to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd :

[0135]

[0136] In the formula, U 2-h and θ 2-h , respectively, are the effective value and phase angle of the h-th harmonic component of signal U2; n is the highest harmonic order of interest.

[0137] Therefore, by measuring the input impedance and frequency response characteristics of the electromagnetic unit, the harmonic voltage correction coefficient can be obtained, solving the problems of high experimental difficulty and large measurement error in the existing technology of obtaining the harmonic voltage correction coefficient by directly measuring the frequency response characteristics of CVT. This method has no impact on the product itself and has the advantages of simple operation and good economy, which is conducive to its widespread application.

[0138] According to another aspect of the invention, a system 500 for calculating the corrected secondary winding output harmonic voltage signal is also provided, with reference to... Figure 5 As shown, the system 500 includes:

[0139] The equivalent parameter calculation module 510 is used to calculate the equivalent resistance R of the parallel connection of the high-voltage capacitor C1 and the medium-voltage capacitor C2 under each harmonic. C Equivalent capacitive X C-h and equivalent impedance value Z C-h ;

[0140] The capacitance correction factor calculation module 520 is used to measure the input impedance of the electromagnetic unit and combine it with the equivalent impedance value Z. C-h Calculate the capacitance correction factor K at each harmonic frequency. 1-h ;

[0141] The electromagnetic correction coefficient calculation module 530 is used to measure the frequency response characteristics of the electromagnetic unit and calculate the electromagnetic correction coefficient K at each harmonic frequency. 2-h ;

[0142] The voltage correction factor calculation module 540 is used to calculate the voltage correction factor K based on the capacitance correction factor K. 1-h and the electromagnetic correction coefficient K 2-h Calculate the correction factor K for the measured voltage of the secondary winding at each harmonic frequency. h ;

[0143] The harmonic voltage signal correction module 550 is used for Fourier decomposition of the output voltage signal U2 across the secondary winding to obtain the harmonic components U. 2H And according to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd .

[0144] Optionally, the module for calculating equivalent parameters includes:

[0145] The equivalent resistance calculation submodule is used to calculate the equivalent resistance R of the parallel connection of the high-voltage capacitor C1 and the medium-voltage capacitor C2 under each harmonic according to the following formula. C :

[0146]

[0147] The equivalent capacitive reactance calculation submodule is used to calculate the equivalent capacitive reactance X of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h :

[0148]

[0149] The equivalent impedance calculation submodule is used to calculate the equivalent impedance Z of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h :

[0150] Z C-h =R C -jX C-h

[0151] In the formula, h is the harmonic order; ω h =2πhf N f is the h-th harmonic angular frequency. N The power frequency is ω. N C N K is the rated capacitor of the voltage divider. CN tanδ is the rated voltage division ratio of the voltage divider. C This is the tangent of the voltage divider loss angle.

[0152] Optionally, the module for calculating the capacitance correction factor includes:

[0153] The capacitor correction factor calculation submodule calculates the capacitor correction factor K at each harmonic frequency according to the following formula. 1-h :

[0154]

[0155] In the formula, Z T-hThis is the measured input impedance value of the electromagnetic unit under the h-th harmonic.

[0156] Optionally, the module for calculating electromagnetic correction coefficients includes:

[0157] The electromagnetic correction coefficient calculation submodule is used to calculate the electromagnetic correction coefficient K at each harmonic frequency according to the following formula. 2-h :

[0158]

[0159] In the formula, K MN The rated voltage ratio of the intermediate transformer; H T (jω h ) represents the frequency response measurement value of the electromagnetic unit under the h-th harmonic.

[0160] Optionally, the voltage correction factor calculation module includes:

[0161] The voltage correction factor calculation submodule is used to calculate the secondary winding measurement voltage correction factor K at each harmonic frequency according to the following formula. h ,

[0162] K h =K 1-h K 2-h

[0163] Optionally, a harmonic voltage signal correction module is defined, including:

[0164] The harmonic component submodule is used to Fourier decompose the output voltage signal U2 across the secondary winding according to the following formula, and obtain the harmonic component U. 2H :

[0165]

[0166] The submodule for determining the corrected harmonic voltage signal is used to determine the voltage correction coefficient K. h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd :

[0167]

[0168] In the formula, U 2-h and θ 2-h , respectively, are the effective value and phase angle of the h-th harmonic component of signal U2; n is the highest harmonic order of interest.

[0169] The system 500 for calculating the corrected secondary winding output harmonic voltage signal according to an embodiment of the present invention corresponds to the method 100 for calculating the corrected secondary winding output harmonic voltage signal according to another embodiment of the present invention, and will not be described again here.

[0170] 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 implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0171] 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, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0172] These 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 function specified in one or more boxes.

[0173] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment 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.

[0174] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0175] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for calculating the corrected secondary winding output harmonic voltage signal, characterized in that, include: Calculate the equivalent resistance R of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic. C Equivalent capacitive X C-h and equivalent impedance value Z C-h ; Measure the input impedance of the electromagnetic unit, and combine it with the equivalent impedance value Z. C-h Calculate the capacitance correction factor K at each harmonic frequency. 1-h ; Measure the frequency response characteristics of the electromagnetic unit and calculate the electromagnetic correction coefficient K at each harmonic frequency. 2-h ; According to the capacitance correction coefficient K 1-h and the electromagnetic correction coefficient K 2-h Calculate the correction factor K for the measured voltage of the secondary winding at each harmonic frequency. h ; Fourier decomposition of the output voltage signal U2 across the secondary winding yields the harmonic components U. 2H And according to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd .

2. The method according to claim 1, characterized in that, Calculate the equivalent resistance R of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic. C Equivalent capacitive X C-h and equivalent impedance value Z C-h ,include: Calculate the equivalent resistance R of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C : Calculate the equivalent capacitive reactance X of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h : Calculate the equivalent impedance Z of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h : Z C-h =R C -jX C-h In the formula, h is the harmonic order; ω h =2πhf N f is the h-th harmonic angular frequency. N The power frequency is ω. N C N K is the rated capacitor of the voltage divider. CN tanδ is the rated voltage division ratio of the voltage divider. C This is the tangent of the voltage divider loss angle.

3. The method according to claim 1, characterized in that, Measure the input impedance of the electromagnetic unit, and combine it with the equivalent impedance value Z. C-h Calculate the capacitance correction factor K at each harmonic frequency. 1-h ,include: Calculate the capacitance correction coefficient K at each harmonic frequency using the following formula. 1-h : In the formula, Z T-h This is the measured input impedance value of the electromagnetic unit under the h-th harmonic.

4. The method according to claim 1, characterized in that, Measure the frequency response characteristics of the electromagnetic unit and calculate the electromagnetic correction coefficient K at each harmonic frequency. 2-h ,include: Calculate the electromagnetic correction coefficient K at each harmonic frequency using the following formula. 2-h : In the formula, K MN The rated voltage ratio of the intermediate transformer; H T (jω h ) represents the frequency response measurement value of the electromagnetic unit under the h-th harmonic.

5. The method according to claim 3 or 4, characterized in that, According to the capacitance correction coefficient K 1-h and the electromagnetic correction coefficient K 2-h Calculate the correction factor K for the measured voltage of the secondary winding at each harmonic frequency. h ,include; Calculate the correction factor K for the secondary winding measured voltage at each harmonic frequency using the following formula. h , K h =K 1-h K 2-h 。 6. The method according to claim 1, characterized in that, Fourier decomposition of the output voltage signal U2 across the secondary winding yields the harmonic components U. 2H And according to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd ,include: According to the following formula, the Fourier decomposition of the output voltage signal U2 across the secondary winding yields the harmonic component U. 2H : According to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd : In the formula, U 2-h and θ 2-h , respectively, are the effective value and phase angle of the h-th harmonic component of signal U2; n is the highest harmonic order of interest.

7. A system for calculating the corrected secondary winding output harmonic voltage signal, characterized in that, include: The equivalent parameter calculation module is used to calculate the equivalent resistance R of the parallel connection of the high-voltage capacitor C1 and the medium-voltage capacitor C2 under each harmonic. C Equivalent capacitive X C-h and equivalent impedance value Z C-h ; The capacitance correction factor calculation module is used to measure the input impedance of the electromagnetic unit, combined with the equivalent impedance value Z. C-h Calculate the capacitance correction factor K at each harmonic frequency. 1-h ; The electromagnetic correction coefficient calculation module is used to measure the frequency response characteristics of the electromagnetic unit and calculate the electromagnetic correction coefficient K at each harmonic frequency. 2-h ; The voltage correction factor calculation module is used to calculate the voltage correction factor K based on the capacitance correction factor K. 1-h and the electromagnetic correction coefficient K 2-h Calculate the correction factor K for the measured voltage of the secondary winding at each harmonic frequency. h ; The module for correcting harmonic voltage signals is used to perform Fourier decomposition of the output voltage signal U2 across the secondary winding to obtain the harmonic components U. 2H And according to the voltage correction coefficient K h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd .

8. The system according to claim 7, characterized in that, The module for calculating equivalent parameters includes: The equivalent resistance calculation submodule is used to calculate the equivalent resistance R of the parallel connection of the high-voltage capacitor C1 and the medium-voltage capacitor C2 under each harmonic according to the following formula. C : The equivalent capacitive reactance calculation submodule is used to calculate the equivalent capacitive reactance X of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h : The equivalent impedance calculation submodule is used to calculate the equivalent impedance Z of the parallel connection of high-voltage capacitor C1 and medium-voltage capacitor C2 under each harmonic according to the following formula. C-h : Z C-h =R C -jX C-h In the formula, h is the harmonic order; ω h =2πhf N f is the h-th harmonic angular frequency. N The power frequency is ω. N C N K is the rated capacitor of the voltage divider. CN tanδ is the rated voltage division ratio of the voltage divider. C This is the tangent of the voltage divider loss angle.

9. The system according to claim 7, characterized in that, The module for calculating the capacitance correction factor includes: The capacitor correction factor calculation submodule calculates the capacitor correction factor K at each harmonic frequency according to the following formula. 1-h : In the formula, Z T-h This is the measured input impedance value of the electromagnetic unit under the h-th harmonic.

10. The system according to claim 7, characterized in that, The module for calculating electromagnetic correction coefficients includes: The electromagnetic correction coefficient calculation submodule is used to calculate the electromagnetic correction coefficient K at each harmonic frequency according to the following formula. 2-h : In the formula, K MN The rated voltage ratio of the intermediate transformer; H T (jω h ) represents the frequency response measurement value of the electromagnetic unit under the h-th harmonic.

11. The system according to claim 9 or 10, characterized in that, The module for calculating voltage correction factors includes: The voltage correction factor calculation submodule is used to calculate the secondary winding measurement voltage correction factor K at each harmonic frequency according to the following formula. h , K h =K 1-h K 2-h 。 12. The system according to claim 7, characterized in that, The module for correcting harmonic voltage signals includes: The harmonic component submodule is used to Fourier decompose the output voltage signal U2 across the secondary winding according to the following formula, and obtain the harmonic component U. 2H : The submodule for determining the corrected harmonic voltage signal is used to determine the voltage correction coefficient K. h For the harmonic component U 2H Make corrections and determine the corrected secondary winding output harmonic voltage signal U. 2Hd : In the formula, U 2-h and θ 2-h , respectively, are the effective value and phase angle of the h-th harmonic component of signal U2; n is the highest harmonic order of interest.

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