A real-time analysis method and system for power quality

Abstract

The present invention discloses a real-time analysis method and system for power quality, belonging to the technical field of power quality, the method comprising: obtaining voltage signals and current signals of a high-speed EMU; converting the voltage signals and current signals into voltage transformer secondary side voltage signals and current transformer current signals respectively; reconstructing the voltage transformer secondary side voltage signals to obtain voltage transformer primary side voltage signals; sampling the voltage transformer primary side voltage signals and current transformer current signals, and performing power quality calculation on the sampling results. The present invention solves the problem of inaccurate power quality calculation caused by inaccurate overvoltage data obtained by the EMU.

Description

Technical Field

[0001] The present invention belongs to the technical field of power quality analysis, and in particular relates to a real-time analysis method and system for power quality. Background Art

[0002] With the rapid development of science and technology and economy, the number and speed of EMUs in my country are constantly increasing, which has greatly improved people's transportation problems. However, with the increasing demand for intelligent EMUs, the corresponding high-power equipment, asymmetric loads and other nonlinear load capacities are also increasing, causing a series of problems in the distribution network system, such as waveform distortion, harmonics and voltage flicker, which seriously affect the power quality of the power supply system.

[0003] The quality of power is directly related to the safe and stable operation of the power grid and EMUs. Good power quality can not only improve the efficiency of electrical equipment, but also reduce power grid losses. However, poor power quality has a huge impact on the power grid, mainly manifested in the following ways: harmonic current intrusion into the power system and EMU system will accelerate the aging of transformer insulation, cause motor failure, shorten the life of the transmission line, affect the normal operation of communication equipment, and even cause resonance in severe cases, causing a sharp increase in harmonic current, causing damage to electrical equipment, and seriously affecting the safe and stable operation of the power system and EMUs. Reactive current intrusion into the power system will cause the voltage on the traction grid side to decrease, affecting the normal use of electrical equipment. At the same time, the large reactive power shortage caused by the traction load will increase the capacity of the reactive compensation device, which will increase the compensation cost and make reactive compensation more difficult.

[0004] Therefore, it is necessary to monitor and record the power quality of the EMU distribution network, control its power quality operation status, and use the power quality data as a basis to provide data support for the problems and solutions of the distribution network, thereby ensuring the reasonable and effective configuration of the EMU power quality and further ensuring the stable and safe operation of the EMU. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a real-time analysis method and system for power quality, which solves the problem of inaccurate power quality calculation caused by inaccurate overvoltage data obtained by EMUs.

[0006] In order to achieve the above-mentioned object of the invention, in a first aspect, the present invention provides a method for real-time analysis of power quality, comprising the following steps:

[0007] S1. Obtain the voltage signal V of the high-speed EMU 1 (t) and current signal I 1 (t);

[0008] S2, using the data acquisition card A / D sampling, the voltage analog signal V 1 (t) and current analog signal V 1 (t) is converted into the voltage transformer secondary side voltage signal V 1 (n) and current transformer current signal I 1 (n);

[0009] S3, the voltage transformer secondary side voltage signal V 1 (n) is reconstructed to obtain the primary side voltage signal V of the voltage transformer 2 (n);

[0010] S4, the primary side voltage signal V of the voltage transformer 2 (n) and current transformer current signal I 1 (n) Perform sampling and calculate the power quality of the sampling results.

[0011] In a second aspect, the present invention provides a real-time analysis system for power quality, comprising an acquisition module, a host computer connected to the acquisition module and internally provided with a data acquisition card, a reconstruction module connected to the host computer, and a sampling module connected to the reconstruction model;

[0012] The acquisition module is used to obtain the voltage signal V of the high-speed train group. 1 (t) and current signal I 1 (t);

[0013] The data acquisition card is used to perform A / D sampling and convert the voltage analog signal V 1 (t) and current analog signal V 1 (t) is converted into the voltage transformer secondary side voltage signal V 1 (n) and current transformer current signal I 1 (n);

[0014] The reconstruction module is used to convert the voltage transformer secondary side voltage signal V 1 (n) is reconstructed to obtain the primary side voltage signal V of the voltage transformer 2 (n);

[0015] The sampling module is used to sample the primary side voltage signal V 2 (n) and current transformer current signal I 1 (n) Perform sampling and calculate the power quality of the sampling results.

[0016] In a third aspect, the present invention provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of the real-time analysis method for power quality when executing the computer program.

[0017] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method for real-time analysis of power quality.

[0018] The beneficial effects of the present invention are:

[0019] The present invention is based on the wide-band transfer characteristics of the voltage transformer and utilizes a reconstruction algorithm to accurately obtain the primary-side voltage signal on the pantograph of the EMU, so as to accurately obtain the power quality of the EMU and compensate for the defect of inaccurate power quality caused by overvoltage in the EMU, thereby being able to accurately grasp the power quality in the distribution network and provide data support for the problems and solutions of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a flow chart of the method of the present invention.

[0021] Figure 2 It is a step-by-step flow chart of step S3 in the present invention.

[0022] Figure 3 It is a step-by-step flow chart of step S301 in the present invention.

[0023] Figure 4 It is a step-by-step flow chart of step S302 in the present invention.

[0024] Figure 5 It is a schematic diagram of the system structure of the present invention. DETAILED DESCRIPTION

[0025] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0026] Those skilled in the art know that the embodiments of the present invention can realize a method, system, electronic device or computer program product. Therefore, the present invention can be specifically implemented in the following forms, namely: complete hardware, complete software (including firmware, microcode, resident software, etc.), or a combination of hardware and software.

[0027] Example 1

[0028] like Figure 1 As shown, in an embodiment of the present invention, a real-time analysis method for power quality is provided, and its implementation method is as follows:

[0029] S1. Obtain the voltage signal V of the high-speed EMU 1 (t) and current signal I 1 (t);

[0030] S2, using the data acquisition card A / D sampling, the voltage analog signal V 1 (t) and current analog signal V 1 (t) is converted into the voltage transformer secondary side voltage signal V 1 (n) and current transformer current signal I 1 (n);

[0031] S3, the voltage transformer secondary side voltage signal V 1 (n) is reconstructed to obtain the primary side voltage signal V of the voltage transformer 2 (n);

[0032] S4, the primary side voltage signal V of the voltage transformer 2 (n) and current transformer current signal I 1 (n) Perform sampling and calculate the power quality of the sampling results.

[0033] In the embodiment of the present invention, the input end of the high-frequency current probe is connected to the secondary side of the current transformer of the high-speed EMU, the input end of the voltage divider is connected to the secondary side of the voltage transformer of the high-speed EMU, and the voltage signal V of the high-speed EMU is obtained by using the high-frequency current probe. 1 (t), use the voltage divider to obtain the current signal I of the high-speed EMU 1 (t), the voltage signal V 1 (t) and current signal I 1 (t) is transmitted to the data acquisition card inside the host computer, and the voltage signal V is converted into 1 (t) and current signal I 1 (t) is converted into a sampling signal (i.e., the secondary voltage signal V 1 (n) and current transformer current signal I 1 (n), and transmit the sampling signal to the host computer, and convert the secondary voltage signal V 1 (n) Reconstruct the primary side voltage signal V of the voltage transformer 2 (n), and then reconstruct the voltage signal V 2(n) and the current transformer current signal I 1 (n) Sampling is performed at a certain sampling frequency and stored to obtain the sampled voltage signal V(n) and current signal I(n). Finally, the power quality is calculated based on the sampled voltage signal V(n) and current signal I(n) to complete the power quality analysis. The power quality calculation includes the voltage effective value U RMS , Current effective value I RMS , calculation of instantaneous power W(i), active power P, apparent power S, reactive power Q and power factor cosθ:

[0034]

[0035]

[0036] W(i)=I(i),i=0,1,2,...,N-1

[0037]

[0038] S=U RMS *I RMS

[0039]

[0040]

[0041] Among them, U RMS represents the effective value of voltage, n represents the length of the sampled voltage signal V(n), i represents any number between 0 and n-1, V 2 (i) represents the square of any value in the sampled voltage signal, I RMS Indicates the effective value of current, I 2 (i) represents the square of any value in the sampled current signal I(n), W(i) represents instantaneous power, I(i) represents any value in the sampled current signal I(n), P represents active power, V(i) represents any value in the sampled voltage signal, S represents apparent power, Q represents reactive power, and cosθ represents power factor.

[0042] In the embodiment of the present invention, the present invention is based on the voltage transformer secondary side voltage signal V 1 (n) Reconstruction to accurately obtain the primary voltage signal V of the voltage transformer on the pantograph of the EMU 2 (n) In this way, accurate power quality can be obtained to compensate for the defect of inaccurate power quality caused by overvoltage in the EMU, so that the power quality in the distribution network can be accurately grasped, and data support can be provided for the problems and solutions of the distribution network.

[0043] Example 2

[0044] For step S3 of Example 1, Figure 2 As shown, it includes the following sub-steps S301-S302:

[0045] S301, obtaining a broadband transfer characteristic of a voltage transformer of a high-speed EMU;

[0046] S302, according to the voltage transformer secondary side voltage signal V 1 (n) and wide-band transfer characteristics, the primary side voltage signal V of the voltage transformer is reconstructed 2 (n).

[0047] In the embodiment of the present invention, the present invention is based on the broadband transmission characteristics of the voltage transformer of the high-speed train, according to the secondary side voltage signal V 1 (n) and wide-band transfer characteristics, the primary side voltage signal V of the voltage transformer is reconstructed 2 (n) Starting from the wide-band transmission characteristics of the voltage transformer, the present invention comprehensively considers the nonlinear characteristics of the voltage transformer at high frequency (relative to 50Hz power frequency), and can obtain more accurate EMU overvoltage, providing data support for the subsequent acquisition of accurate power quality.

[0048] Example 3

[0049] For step S301 of embodiment 2, Figure 3 As shown, it includes the following sub-steps S3011 to S3016:

[0050] S3011, generating a single-frequency sinusoidal signal, and injecting the single-frequency sinusoidal signal into the primary side of the voltage transformer;

[0051] S3012, simultaneously measuring the primary and secondary side signals of the voltage transformer;

[0052] S3013, respectively recording the amplitude and phase difference of the primary and secondary side signals of the voltage transformer, wherein the phase difference is the phase-frequency characteristic of the single frequency point;

[0053] S3014, determining the amplitude-frequency characteristic of the voltage transformer at the single frequency point according to the amplitudes of the primary side and the secondary side of the voltage transformer;

[0054] S3015, changing the signal frequency at a fixed frequency interval, and determining whether the frequency signal reaches a preset frequency threshold, if so, determining the phase-frequency characteristic and amplitude-frequency characteristic of the voltage transformer after changing the signal frequency, and proceeding to step S3016, otherwise, returning to step S3011;

[0055] S3016, combining the obtained multiple single-frequency amplitude-frequency characteristics and phase-frequency characteristics in ascending order according to frequency, obtaining the wide-band transfer characteristics of the high-speed EMU voltage transformer, and proceeding to step S302.

[0056] In the embodiment of the present invention, it should be noted that: the secondary side signal measured in step S3012 is the secondary side signal after the single frequency signal is injected into the primary side, and the secondary side voltage signal of the voltage transformer in step S2 is the actual overvoltage signal.

[0057] In the embodiment of the present invention, in order to obtain the broadband transfer characteristics of the voltage transformer of the EMU, a frequency sweep measurement is performed.

[0058] In the embodiment of the present invention, a signal generator and an oscilloscope can be used to perform frequency sweep measurement. Take the example of obtaining the wideband transfer characteristics of a voltage transformer between 1MHz and 5MHz. A single-frequency sinusoidal signal is generated by a signal generator and injected into the primary side of the voltage transformer. The present invention can use an oscilloscope to simultaneously measure the primary and secondary side signals of the voltage transformer and record the amplitudes M of the primary and secondary side signals. 1 and M 2 , and the phase difference φ, the amplitude of the two divided (primary side / secondary side) is the amplitude-frequency characteristic A of the voltage transformer at the single frequency point, and the phase difference φ (primary side phase minus secondary side phase) is the phase-frequency characteristic of the single frequency point. That is:

[0059]

[0060] The signal frequency is changed at a certain frequency interval, such as 10kHz interval, and increases to 5MHz. If the preset frequency threshold is reached, the phase-frequency characteristic and amplitude-frequency characteristic of the voltage transformer after the frequency change are determined, and the amplitude-frequency characteristics and phase-frequency characteristics of multiple single frequency points between 1MHz and 5MHz are combined in ascending order according to the frequency, and the wide-band transfer characteristic H(ω) of the voltage transformer between 1MHz and 5MHz is obtained, including the amplitude-frequency characteristic A(ω) of the wide-band transfer characteristic of the voltage transformer and the phase-frequency characteristic φ(ω) of the wide-band transfer characteristic of the voltage transformer:

[0061] H(ω)=A(ω)*e i*φ(ω)

[0062] Among them, H(ω) represents the wide-band transfer characteristic of the voltage transformer, A(ω) represents the amplitude-frequency characteristic of the wide-band transfer characteristic of the voltage transformer, e represents a natural constant, i represents an imaginary unit, and φ(ω) represents the phase-frequency characteristic of the wide-band transfer characteristic of the voltage transformer.

[0063] In an embodiment of the present invention, the present invention first determines the phase-frequency characteristic and amplitude-frequency characteristic of a single frequency point, and then changes the signal frequency at a certain frequency interval to obtain the phase-frequency characteristic and amplitude-frequency characteristic after the signal frequency is changed, and sorts and combines the amplitude-frequency characteristics and phase-frequency characteristics of multiple single-frequency points in ascending order of frequency to obtain a more accurate wide-band transfer characteristic of the voltage transformer, thereby providing a basis for subsequently obtaining more accurate overvoltage data.

[0064] Example 4

[0065] For step S302 of embodiment 2, Figure 4 As shown, it includes the following sub-steps S3021 to S3024:

[0066] S3021, the voltage transformer secondary side voltage signal V 1 (n) performing a fast Fourier transform to obtain a secondary side frequency domain signal, and converting the secondary side frequency domain signal into a secondary side frequency domain symmetric signal that is symmetric at zero frequency point;

[0067] S3022, supplementing the negative frequency of the broadband transfer characteristic, and performing linear interpolation processing on the supplemented broadband transfer characteristic to obtain a new broadband transfer characteristic;

[0068] S3023, calculating and obtaining a primary side frequency domain signal according to the new wideband transfer characteristics and the secondary side frequency domain symmetric signal;

[0069] S3024, performing inverse fast Fourier transform on the primary side frequency domain signal to reconstruct a primary side voltage signal V of the voltage transformer 2 (n), and reconstruct the primary side voltage signal V of the voltage transformer 2 (n) Perform smoothing.

[0070] In the embodiment of the present invention, according to the wide-band transfer characteristics of the voltage transformer and the secondary voltage signal V 1 (n), the reconstruction algorithm is used to reconstruct the primary side voltage signal V of the voltage transformer 2 (n). The reconstruction process is as follows:

[0071] (1) The secondary voltage signal V of the voltage transformer measured at a certain sampling frequency 1 (n) and save the voltage transformer secondary side voltage signal V 1 (n) Perform fast Fourier transform (fft) to obtain the secondary side frequency domain signal V 2(ω), converting the frequency domain signal at this time into data that is symmetrical about the zero frequency point, including the amplitude-frequency characteristic Mag(ω) of the secondary side frequency domain symmetrical signal and the phase-frequency characteristic Pha(ω) of the secondary side frequency domain symmetrical signal, where the sampling frequency is not greater than the maximum signal frequency for obtaining the wide-band transfer characteristics.

[0072] (2) The broadband transfer characteristics obtained by the above measurement are supplemented with the negative frequency part to ensure that the frequency distribution is symmetrical about the zero frequency point, the amplitude-frequency characteristics of the negative frequency and the positive frequency are equal, and the phase-frequency characteristics are opposite. The broadband transfer characteristics after supplementing the negative frequency are linearly interpolated to ensure that the frequency interval is the same as the frequency interval, and finally the new broadband transfer characteristics H are obtained. 1 (ω), including the amplitude-frequency characteristic A of the new broadband transfer feature 1 (ω) and the phase-frequency characteristic φ of the new broadband transfer characteristic 1 (ω).

[0073] (3) Multiply the secondary side frequency domain symmetrical signal with the broadband transfer characteristic, that is, multiply the amplitude-frequency characteristics and add the phase-frequency characteristics to obtain the primary side frequency domain signal V 1 (ω), and the obtained primary side frequency domain signal is subjected to inverse fast Fourier transform (ifft) to obtain the primary side voltage signal V 2 (n).

[0074] (4) The reconstructed primary side voltage signal V 2 (n) Then use the smoothing algorithm to perform smoothing processing to eliminate data oscillation and finally obtain the EMU overvoltage signal.

[0075] In the embodiment of the present invention, the smoothing algorithm includes but is not limited to a moving smoothing algorithm, a local regression smoothing algorithm, a local weighted regression smoothing algorithm, an SG smoothing algorithm, a robust local regression smoothing algorithm or a robust local weighted regression smoothing algorithm.

[0076] In the embodiment of the present invention, the reconstruction process includes fast Fourier transform and inverse fast Fourier transform, and the voltage transformer secondary side voltage signal V 1 (n) Perform fast Fourier transform to obtain the secondary side frequency domain signal, multiply the secondary side frequency domain signal with the wide-band transfer characteristic, that is, multiply the amplitude, add the phase to obtain the primary side frequency domain signal, and finally perform inverse fast Fourier transform and smoothing on the primary side frequency domain signal to obtain the overvoltage (time domain) data, that is, the reconstructed primary side voltage signal V of the voltage transformer 2 (n).

[0077] In the embodiment of the present invention, according to the voltage transformer secondary side voltage signal V 1 (n) and the wide-band transfer characteristics of the voltage transformer, the primary side voltage signal V of the voltage transformer is obtained by using the reconstruction algorithm 2(n), which makes up for the defect that the current overvoltage acquisition method cannot take into account the transfer characteristics of the transformer within a wide frequency band, effectively improves the accuracy of the acquired overvoltage data, and provides data support for subsequent power quality analysis.

[0078] Example 5

[0079] With respect to step S3024 in Embodiment 4, the primary side voltage signal V 2 The expression of (n) is as follows:

[0080] V 2 (n)=ifft(V 1 (ω)

[0081]

[0082]

[0083] V 2 (ω)=fft(V 2 (t))=Mag(ω)*e i*Pha(ω)

[0084] Where ifft(·) represents the inverse fast Fourier transform, V 1 (ω) represents the primary side frequency domain signal, V 2 (ω) represents the secondary side frequency domain symmetrical signal, H 1 (ω) represents the new broadband transfer characteristics, Mag(ω) represents the amplitude-frequency characteristics of the secondary side frequency domain symmetrical signal, A 1 (ω) represents the amplitude-frequency characteristic of the new wideband transfer feature, e represents a natural constant, i represents an imaginary unit, Pha(ω) represents the phase-frequency characteristic of the secondary side frequency domain symmetrical signal, φ 1 (ω) represents the phase-frequency characteristic of the new broadband transfer feature, and fft(·) represents the fast Fourier transform.

[0085] In the embodiment of the present invention, the voltage transformer secondary side voltage signal V 1 (n) Perform fast Fourier transform to obtain the secondary side frequency domain signal, multiply the secondary side frequency domain signal with the wide-band transfer characteristic, that is, multiply the amplitude, add the phase to obtain the primary side frequency domain signal, and finally perform inverse fast Fourier transform and smoothing on the primary side frequency domain signal to obtain the overvoltage (time domain) data, that is, the reconstructed primary side voltage signal V of the voltage transformer 2 (n).

[0086] In summary, in the embodiment of the present invention, the present invention is based on the voltage transformer secondary side voltage signal V 1 (n) and the wide-band transfer characteristics of the transformer, the reconstruction algorithm is used to obtain the primary side voltage signal V of the voltage transformer2 (n). The present invention makes up for the defect that the current method of obtaining overvoltage cannot take into account the transfer characteristics of the voltage transformer within a wide frequency band, and effectively improves the accuracy of the obtained overvoltage data. At the same time, the present invention takes into account the transfer characteristics of the voltage transformer within a wide frequency band, obtains more accurate overvoltage data, and provides data support for subsequent power quality analysis.

[0087] Example 6

[0088] Based on the same inventive concept, an embodiment of the present invention also provides a real-time analysis system for power quality. Since the principle solved by the system is similar to the real-time analysis method for power quality, the implementation of the system can refer to the implementation of the method, and the repeated parts will not be repeated.

[0089] Figure 5 is a real-time analysis system for power quality in an embodiment of the present invention, such as Figure 5 As shown, the real-time analysis system for power quality includes an acquisition module, a host computer connected to the acquisition module and internally provided with a data acquisition card, a reconstruction module connected to the host computer, and a sampling module connected to the reconstruction model;

[0090] The acquisition module is used to obtain the voltage signal V of the high-speed train group. 1 (t) and current signal I 1 (t);

[0091] The data acquisition card is used to perform A / D sampling and convert the voltage analog signal V 1 (t) and current analog signal V 1 (t) is converted into the voltage transformer secondary side voltage signal V 1 (n) and current transformer current signal I 1 (n);

[0092] The reconstruction module is used to convert the voltage transformer secondary side voltage signal V 1 (n) is reconstructed to obtain the primary side voltage signal V of the voltage transformer 2 (n);

[0093] The sampling module is used to sample the primary side voltage signal V 2 (n) and current transformer current signal I 1 (n) Perform sampling and calculate the power quality of the sampling results.

[0094] In one embodiment, it also includes a power supply module for supplying power to the host computer;

[0095] The power supply module includes a UPS power supply for supplying power to the host computer, an isolation transformer connected to the UPS power supply, and a power supply connected to the isolation transformer.

[0096] In one embodiment, the acquisition module includes a high-frequency current probe and a voltage divider;

[0097] The high-frequency current probe is connected to the secondary side of the current transformer of the high-speed EMU, and the voltage divider is connected to the secondary side of the voltage transformer of the high-speed EMU.

[0098] In the embodiment of the present invention, the input end of the high-frequency current probe is connected to the secondary side of the current transformer of the high-speed EMU, the input end of the voltage divider is connected to the secondary side of the voltage transformer of the high-speed EMU, and the voltage signal V of the high-speed EMU is obtained by using the high-frequency current probe. 1 (t), use the voltage divider to obtain the current signal I of the high-speed EMU 1 (t), the voltage signal V 1 (t) and current signal I 1 (t) is transmitted to the data acquisition card inside the host computer, and the voltage signal V is converted into 1 (t) and current signal I 1 (t) is converted into a sampling signal (i.e., the secondary voltage signal V 1 (n) and current transformer current signal I 1 (n), and transmit the sampling signal to the host computer, and convert the secondary voltage signal V 1 (n) Reconstruct the primary side voltage signal V of the voltage transformer 2 (n), and then reconstruct the voltage signal V 2 (n) and the current transformer current signal I 1 (n) Sampling is performed at a certain sampling frequency and saved to obtain the sampled voltage signal V(n) and current signal I(n). Finally, the power quality is calculated based on the sampled voltage signal V(n) and current signal I(n) to complete the power quality analysis.

[0099] In the embodiment of the present invention, a UPS power supply is used to power the host computer.

[0100] In the embodiment of the present invention, a power supply is used to power an isolation transformer, and the isolation transformer is used to stabilize the voltage to prevent power supply voltage fluctuations from affecting the device.

[0101] In one embodiment, the reconstruction module includes:

[0102] An acquisition unit, used for acquiring a broadband transfer characteristic of a voltage transformer of a high-speed EMU;

[0103] A reconstruction unit is used to reconstruct the voltage transformer according to the secondary side voltage signal V 1 (n) and wide-band transfer characteristics, the primary side voltage signal V of the voltage transformer is reconstructed 2 (n).

[0104] In one embodiment, the acquisition unit includes:

[0105] A signal generating subunit, used for generating a single-frequency sinusoidal signal, and injecting the single-frequency sinusoidal signal into the primary side of the voltage transformer;

[0106] A first calculation subunit, used for simultaneously measuring the primary side and secondary side signals of the voltage transformer;

[0107] A second calculation subunit is used to record the amplitude and phase difference of the primary side and secondary side signals of the voltage transformer respectively, wherein the phase difference is the phase-frequency characteristic of the single frequency point;

[0108] A third calculation subunit, configured to determine the amplitude-frequency characteristic of the voltage transformer at the single frequency point according to the amplitudes of the primary side and the secondary side of the voltage transformer;

[0109] A judging subunit, used to change the signal frequency at a fixed frequency interval, and judge whether the frequency signal reaches a preset frequency threshold, if so, determine the phase-frequency characteristic and amplitude-frequency characteristic of the voltage transformer after changing the signal frequency, otherwise, continue iteration;

[0110] The fourth calculation subunit is used to combine the obtained multiple single-frequency amplitude-frequency characteristics and phase-frequency characteristics in ascending order according to frequency, so as to obtain the wide-band transfer characteristics of the voltage transformer of the high-speed EMU.

[0111] In one embodiment, the reconstruction unit includes:

[0112] The fifth calculation subunit is used to calculate the voltage transformer secondary side voltage signal V 1 (n) performing a fast Fourier transform to obtain a secondary side frequency domain signal, and converting the secondary side frequency domain signal into a secondary side frequency domain symmetric signal that is symmetric at zero frequency point;

[0113] a sixth calculation subunit, configured to supplement the negative frequency of the broadband transfer feature, and perform linear interpolation processing on the supplemented broadband transfer feature to obtain a new broadband transfer feature;

[0114] a seventh calculation subunit, configured to calculate a primary side frequency domain signal according to the new wideband transfer characteristic and the secondary side frequency domain symmetric signal;

[0115] The eighth calculation subunit is used to perform an inverse fast Fourier transform on the primary side frequency domain signal to reconstruct the primary side voltage signal V of the voltage transformer. 2 (n), and reconstruct the primary side voltage signal V of the voltage transformer 2 (n) Perform smoothing.

[0116] In one embodiment, the primary side voltage signal V 2 The expression of (n) is as follows:

[0117] V 2 (n)=ifft(V 1 (ω)

[0118]

[0119]

[0120] V 2 (ω)=fft(V 2 (t))=Mag(ω)*e i*Pha(ω)

[0121] Where ifft(·) represents the inverse fast Fourier transform, V 1 (ω) represents the primary side frequency domain signal, V 2 (ω) represents the secondary side frequency domain symmetrical signal, H 1 (ω) represents the new broadband transfer characteristics, Mag(ω) represents the amplitude-frequency characteristics of the secondary side frequency domain symmetrical signal, A 1 (ω) represents the amplitude-frequency characteristic of the new wideband transfer feature, e represents a natural constant, i represents an imaginary unit, Pha(ω) represents the phase-frequency characteristic of the secondary side frequency domain symmetrical signal, φ 1 (ω) represents the phase-frequency characteristic of the new broadband transfer feature, fft(·) represents the fast Fourier transform, V 2 (t) represents the secondary voltage measured at a fixed frequency.

[0122] In an embodiment of the present invention, the present application may divide the functional units according to the real-time analysis method of the power quality. For example, each function may be divided into each functional unit, or two or more functions may be integrated into one processing unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of a software functional unit. It should be noted that the division of the units in the present invention is schematic and is only a logical division. There may be other division methods in actual implementation.

[0123] In the embodiment of the present invention, in order to realize the principle and beneficial effect of the real-time analysis method for power quality, the real-time analysis system for power quality includes hardware structures and / or software modules corresponding to the execution of various functions. It should be easily appreciated by those skilled in the art that, in combination with the schematic units and algorithm steps described in the embodiments disclosed in the present invention, the present invention can be implemented in the form of hardware and / or a combination of hardware and computer software. Whether a function is executed in a hardware or computer software driven manner depends on the specific application and design constraints of the technical solution. Different methods can be used for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the present application.

[0124] In summary, the real-time analysis system for power quality in the embodiment of the present invention is based on the wide-band transmission characteristics of the voltage transformer, and uses a reconstruction algorithm to accurately obtain the primary-side voltage signal on the pantograph of the EMU, so as to more accurately obtain the power quality of the EMU, to compensate for the defect of inaccurate power quality caused by overvoltage in the EMU, thereby being able to accurately grasp the power quality in the distribution network, and provide data support for the problems and solutions generated by the distribution network.

[0125] Example 7

[0126] An embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of the real-time analysis method for power quality described in any one of Embodiments 1 to 5 are implemented. For example, when the processor executes the computer program, the following contents may be implemented:

[0127] S1. Obtain the voltage signal V of the high-speed EMU 1 (t) and current signal I 1 (t);

[0128] S2, using the data acquisition card A / D sampling, the voltage analog signal V 1 (t) and current analog signal V 1 (t) is converted into the voltage transformer secondary side voltage signal V 1 (n) and current transformer current signal I 1 (n);

[0129] S3, the voltage transformer secondary side voltage signal V 1 (n) is reconstructed to obtain the primary side voltage signal V of the voltage transformer 2 (n);

[0130] S4, the primary side voltage signal V of the voltage transformer 2 (n) and current transformer current signal I 1(n) Perform sampling and calculate the power quality of the sampling results.

[0131] In this embodiment, the electronic device may include: a processor, a memory, a bus and a communication interface. The processor, the communication interface and the memory are connected via a bus. The memory stores a computer program that can be run on the processor. When the processor runs the computer program, it executes part or all of the steps of the real-time analysis method for power quality provided in any of the aforementioned embodiments 1 to 5 of the present application.

[0132] In summary, the real-time analysis system for power quality in the embodiment of the present invention is based on the wide-band transmission characteristics of the voltage transformer, and uses a reconstruction algorithm to accurately obtain the primary-side voltage signal on the pantograph of the EMU, so as to more accurately obtain the power quality of the EMU, to compensate for the defect of inaccurate power quality caused by overvoltage in the EMU, thereby being able to accurately grasp the power quality in the distribution network, and provide data support for the problems and solutions generated by the distribution network.

[0133] Example 8

[0134] An embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the real-time analysis method for power quality described in any one of Embodiments 1 to 5 are implemented. For example, when the processor executes the program, the following contents may be implemented:

[0135] S1. Obtain the voltage signal V of the high-speed EMU 1 (t) and current signal I 1 (t);

[0136] S2, using the data acquisition card A / D sampling, the voltage analog signal V 1 (t) and current analog signal V 1 (t) is converted into the voltage transformer secondary side voltage signal V 1 (n) and current transformer current signal I 1 (n);

[0137] S3, the voltage transformer secondary side voltage signal V 1 (n) is reconstructed to obtain the primary side voltage signal V of the voltage transformer 2 (n);

[0138] S4, the primary side voltage signal V of the voltage transformer 2 (n) and current transformer current signal I 1 (n) Perform sampling and calculate the power quality of the sampling results.

[0139] In summary, the real-time analysis system for power quality in the embodiment of the present invention is based on the wide-band transmission characteristics of the voltage transformer, and uses a reconstruction algorithm to accurately obtain the primary-side voltage signal on the pantograph of the EMU, so as to more accurately obtain the power quality of the EMU, to compensate for the defect of inaccurate power quality caused by overvoltage in the EMU, thereby being able to accurately grasp the power quality in the distribution network, and provide data support for the problems and solutions generated by the distribution network.

[0140] The computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special computer. The readable storage medium is coupled to the processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. The readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in an application-specific integrated circuit (ASIC). The processor and the readable storage medium can also exist as discrete components in the real-time analysis system for power quality.

[0141] The embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may 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 codes. With reference to the process and / or block diagram of the method, device (device), and computer program product according to the embodiments of the present invention, it should be understood that each process and / or block diagram in the flow chart and / or block diagram, as well as the combination of the flow chart and / or block diagram, can be implemented by computer program instructions, and these computer program instructions can be provided to a computer-readable memory of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing device that works in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device, which is implemented in the flow chart. Figure 1 A process or multiple processes and / or boxes Figure 1These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing one or more processes and / or blocks in the flowchart. Figure 1 A step that specifies a function in one or more boxes.

[0142] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A real-time analysis method for power quality, characterized in that: The following steps are involved: S1, obtaining the voltage signal V1(t) and current signal I1(t) of the high-speed EMU; S2, using a data acquisition card A / D sampling to convert the voltage signal V1(t) and the current signal V1(t) into a voltage transformer secondary side voltage signal V1(n) and a current transformer current signal I1(n); S3, reconstructing the voltage transformer secondary side voltage signal V1(n) to obtain the voltage transformer primary side voltage signal V2(n); The S3 comprises the following steps: S301, obtaining a broadband transfer characteristic of a voltage transformer of a high-speed EMU; S302, according to the voltage transformer secondary side voltage signal V1 (n ) and wide-band transfer characteristics, and reconstruct the primary side voltage signal V2(n) of the voltage transformer; The S302 includes the following steps: S3021, performing fast Fourier transform on the secondary side voltage signal V1(n) of the voltage transformer to obtain a secondary side frequency domain signal, and converting the secondary side frequency domain signal into a secondary side frequency domain symmetrical signal that is symmetrical at zero frequency point; S3022, supplementing the negative frequency of the broadband transfer characteristic, and performing linear interpolation processing on the supplemented broadband transfer characteristic to obtain a new broadband transfer characteristic; S3023, calculating and obtaining a primary side frequency domain signal according to the new wideband transfer characteristics and the secondary side frequency domain symmetric signal; S3024, performing an inverse fast Fourier transform on the primary side frequency domain signal to reconstruct a voltage transformer primary side voltage signal V2(n), and smoothing the reconstructed voltage transformer primary side voltage signal V2(n); S4. Sampling the primary side voltage signal V2(n) of the voltage transformer and the current signal I1(n) of the current transformer, and performing power quality calculation on the sampling results.

2. The real-time analysis method for power quality according to claim 1, characterized in that: The S301 includes the following steps: S3011, generating a single-frequency sinusoidal signal, and injecting the single-frequency sinusoidal signal into the primary side of the voltage transformer; S3012, simultaneously measuring the primary and secondary side signals of the voltage transformer; S3013, respectively recording the amplitude and phase difference of the primary and secondary side signals of the voltage transformer, wherein the phase difference is the phase-frequency characteristic of the single frequency point; S3014, determining the amplitude-frequency characteristic of the voltage transformer at the single frequency point according to the amplitudes of the primary side and the secondary side of the voltage transformer; S3015, changing the signal frequency at a fixed frequency interval, and determining whether the frequency signal reaches a preset frequency threshold, if so, determining the phase-frequency characteristic and amplitude-frequency characteristic of the voltage transformer after changing the signal frequency, and proceeding to step S3016, otherwise, returning to step S3011; S3016, combining the obtained multiple single-frequency amplitude-frequency characteristics and phase-frequency characteristics in ascending order according to frequency, obtaining the wide-band transfer characteristics of the high-speed EMU voltage transformer, and proceeding to step S302.

3. The real-time analysis method for power quality according to claim 1, characterized in that: The expression of the primary side voltage signal V2(n) of the voltage transformer in S3024 is as follows: in, represents the inverse fast Fourier transform, represents the primary side frequency domain signal, represents the secondary side frequency domain symmetrical signal, represents the new broadband transfer characteristics, It represents the amplitude-frequency characteristics of the secondary side frequency domain symmetrical signal, The amplitude-frequency characteristic representing the new broadband transfer feature, represents a natural constant, represents the imaginary unit, represents the phase-frequency characteristics of the secondary side frequency domain symmetrical signal, The phase-frequency characteristic representing the new broadband transfer feature, stands for Fast Fourier Transform.

4. A real-time analysis system for power quality, characterized in that: It includes an acquisition module, a host computer connected to the acquisition module and internally provided with a data acquisition card, a reconstruction module connected to the host computer, and a sampling module connected to the reconstruction module; The acquisition module is used to obtain the voltage signal V1(t) and the current signal I1(t) of the high-speed train set; The data acquisition card is used for performing A / D sampling to convert the voltage signal V1(t) and the current signal V1(t) into a voltage transformer secondary side voltage signal V1(n) and a current transformer current signal I1(n); The reconstruction module is used to reconstruct the voltage transformer secondary side voltage signal V1(n) to obtain the voltage transformer primary side voltage signal V2(n); The reconstruction module includes: An acquisition unit, used for acquiring a broadband transfer characteristic of a voltage transformer of a high-speed EMU; A reconstruction unit, configured to reconstruct a voltage transformer primary side voltage signal V2(n) according to the voltage transformer secondary side voltage signal V1(n) and the broadband transmission characteristic; The reconstruction unit comprises: a fifth calculation subunit, configured to perform a fast Fourier transform on the secondary side voltage signal V1(n) of the voltage transformer to obtain a secondary side frequency domain signal, and convert the secondary side frequency domain signal into a secondary side frequency domain symmetrical signal that is symmetrical at a zero frequency point; a sixth calculation subunit, configured to supplement the negative frequency of the broadband transfer feature, and perform linear interpolation processing on the supplemented broadband transfer feature to obtain a new broadband transfer feature; a seventh calculation subunit, configured to calculate a primary side frequency domain signal according to the new wideband transfer characteristic and the secondary side frequency domain symmetric signal; an eighth calculation subunit, configured to perform an inverse fast Fourier transform on the primary side frequency domain signal, reconstruct a voltage transformer primary side voltage signal V2(n), and smooth the reconstructed voltage transformer primary side voltage signal V2(n); The sampling module is used to perform sampling processing on the primary side voltage signal V2(n) of the voltage transformer and the current signal I1(n) of the current transformer, and perform power quality calculation on the sampling results.

5. The real-time analysis system for power quality according to claim 4, characterized in that: Also includes a power supply module for supplying power to the host computer; The power supply module includes a UPS power supply for supplying power to the host computer, an isolation transformer connected to the UPS power supply, and a power supply connected to the isolation transformer.

6. The real-time analysis system for power quality according to claim 5, characterized in that: The acquisition module includes a high-frequency current probe and a voltage divider; The high-frequency current probe is connected to the secondary side of the current transformer of the high-speed EMU, and the voltage divider is connected to the secondary side of the voltage transformer of the high-speed EMU.

7. The real-time analysis system for power quality according to claim 4, characterized in that: The acquisition unit comprises: A signal generating subunit, used for generating a single-frequency sinusoidal signal, and injecting the single-frequency sinusoidal signal into the primary side of the voltage transformer; A first calculation subunit, used for simultaneously measuring the primary side and secondary side signals of the voltage transformer; A second calculation subunit is used to record the amplitude and phase difference of the primary side and secondary side signals of the voltage transformer respectively, wherein the phase difference is the phase-frequency characteristic of the single frequency point; A third calculation subunit, configured to determine the amplitude-frequency characteristic of the voltage transformer at the single frequency point according to the amplitudes of the primary side and the secondary side of the voltage transformer; A judging subunit, used to change the signal frequency at a fixed frequency interval, and judge whether the frequency signal reaches a preset frequency threshold, if so, determine the phase-frequency characteristic and amplitude-frequency characteristic of the voltage transformer after changing the signal frequency, otherwise, continue iteration; The fourth calculation subunit is used to combine the obtained multiple single-frequency amplitude-frequency characteristics and phase-frequency characteristics in ascending order according to frequency, so as to obtain the wide-band transfer characteristics of the voltage transformer of the high-speed EMU.

8. The real-time analysis system for power quality according to claim 4, characterized in that: The primary side voltage signal of the voltage transformer V 2 (n) The expression is as follows: in, represents the inverse fast Fourier transform, represents the primary side frequency domain signal, represents the secondary side frequency domain symmetrical signal, represents the new broadband transfer characteristics, It represents the amplitude-frequency characteristics of the secondary side frequency domain symmetrical signal, The amplitude-frequency characteristic representing the new broadband transfer feature, represents a natural constant, represents the imaginary unit, represents the phase-frequency characteristics of the secondary side frequency domain symmetrical signal, The phase-frequency characteristic representing the new broadband transfer feature, represents the fast Fourier transform, Represents the secondary voltage measured at a fixed frequency.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the real-time analysis method for power quality described in any one of claims 1 to 3 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the real-time analysis method for power quality according to any one of claims 1 to 3 are implemented.

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