Phase-locked loop suitable for amplitude-frequency modulation signal measurement and working method thereof

Abstract

The invention discloses a phase-locked loop suitable for amplitude-frequency modulation signal measurement and a working method thereof, and the phase-locked loop comprises a delay phase correction module which is used for carrying out the delay phase correction of a three-phase voltage signal to obtain a correction value; the FFT measurement module is used for performing FFT measurement on the correction value to obtain oscillation frequency; and the fundamental wave frequency measurement module is used for averaging the oscillation frequency and the angular frequency tracked by the phase-locked loop to obtain a fundamental wave frequency measurement value. According to the invention, an improved measurement loop is added on an existing conventional phase-locked loop to measure an amplitude-frequency modulation signal, so that the phase-locked loop can track an alternating current signal phase modulated by actual amplitude and frequency without error. The amplitude and frequency of the amplitude-frequency modulation signal can be rapidly extracted under the rotating coordinate system, the accuracy of the amplitude-frequency modulation signal measurement method based on the phase-locked loop is guaranteed, and rapid analysis and suppression of oscillation are achieved in engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of phase-locked loops, and in particular to a phase-locked loop suitable for measuring amplitude-frequency modulation signals and a working method thereof. Background Art

[0002] While the high proportion of power electronic equipment connected to the grid improves the flexibility of power conversion in the system, it also introduces multi-feature oscillation problems of various forms. Accurate description and measurement of oscillation data and waveforms are the prerequisites for oscillation analysis and suppression. Based on the research idea of ​​oscillating amplitude-frequency modulation signals, there must be effective means to quickly extract and measure the signal amplitude and frequency, and the phase-locked loop is an effective means to achieve signal measurement in the rotating coordinate system of amplitude-frequency modulation signals.

[0003] In practice, in order to obtain the rotation angle of the rotation transformation, a phase-locked loop (PLL) is often used to measure the rotation angle of the actual AC signal. Its synchronization principle is usually to take uq as the control object. When the phase is locked, the voltage q-axis component uq is 0, and the coordinates are synchronously transformed through closed-loop control to complete phase locking and frequency measurement.

[0004] However, conventional phase-locked loops cannot achieve error-free tracking of amplitude-frequency modulated signals under the action of oscillating signals. Summary of the invention

[0005] In view of the problems in the prior art, an embodiment of the present invention provides a phase-locked loop suitable for measuring amplitude-frequency modulated signals and a working method thereof, which can achieve error-free tracking of amplitude-frequency modulated signals.

[0006] In order to achieve the above object, an embodiment of the present invention provides a phase-locked loop suitable for measuring amplitude-frequency modulated signals, comprising:

[0007] A delayed phase correction module is used to perform delayed phase correction on the three-phase voltage signal to obtain a correction value;

[0008] An FFT measurement module is used to perform FFT measurement on the correction value to obtain an oscillation frequency;

[0009] The fundamental frequency measurement module is used to perform average processing on the oscillation frequency and the angular frequency tracked by the phase-locked loop to obtain a fundamental frequency measurement value.

[0010] In one embodiment, it further includes:

[0011] The frequency modulation signal measurement module is used to perform amplitude gain compensation on the difference between the fundamental frequency and the angular frequency to obtain a frequency modulation signal measurement value.

[0012] In one embodiment, it further includes:

[0013] The amplitude modulation signal measurement module is used to perform integration calculation on the fundamental frequency measurement value and the frequency modulation signal measurement value, and then perform dq coordinate transformation to obtain the amplitude modulation signal measurement value.

[0014] In one embodiment, the fundamental frequency measurement value is processed by the delayed phase correction module and then added to the frequency modulation signal measurement value, and then an integral calculation is performed, and then a dq coordinate transformation is performed to obtain the amplitude modulation signal measurement value.

[0015] In one embodiment, the dq coordinate transformation adopts the following formula:

[0016]

[0017] Where ω1 is the frequency of the amplitude / frequency modulation signal, and They represent the initial phases of the amplitude modulation signal and the frequency modulation signal respectively, U0 represents the initial voltage of the node, A1 and U1 represent the frequency modulation index and the amplitude modulation index respectively.

[0018] An embodiment of the present invention provides a working method of a phase-locked loop applicable to amplitude-frequency modulation signal measurement, comprising:

[0019] Performing delayed phase correction on the three-phase voltage signal to obtain a correction value;

[0020] Performing FFT measurement on the correction value to obtain the oscillation frequency;

[0021] The oscillation frequency and the angular frequency tracked by the phase-locked loop are averaged to obtain a fundamental frequency measurement value.

[0022] In one embodiment, the method further includes: performing amplitude gain compensation on the difference between the fundamental frequency and the angular frequency to obtain a frequency modulation signal measurement value.

[0023] In one embodiment, the method further includes: integrating the fundamental frequency measurement value and the frequency modulation signal measurement value, and then performing dq coordinate transformation to obtain the amplitude modulation signal measurement value.

[0024] In one embodiment, the fundamental frequency measurement value is processed by the delayed phase correction module and then added to the frequency modulation signal measurement value, and then an integral calculation is performed, and then a dq coordinate transformation is performed to obtain the amplitude modulation signal measurement value.

[0025] In one embodiment, the dq coordinate transformation adopts the following formula:

[0026]

[0027] Where ω1 is the frequency of the amplitude modulation signal and the frequency modulation signal, and They represent the initial phases of the amplitude modulation signal and the frequency modulation signal respectively, U0 represents the initial voltage of the node, A1 and U1 represent the frequency modulation index and the amplitude modulation index respectively.

[0028] The embodiment of the present invention provides a phase-locked loop suitable for measuring amplitude-frequency modulated signals and a working method thereof, the phase-locked loop comprising: a delayed phase correction module for performing delayed phase correction on a three-phase voltage signal to obtain a correction value; an FFT measurement module for performing FFT measurement on the correction value to obtain an oscillation frequency; and a fundamental frequency measurement module for performing average value processing on the oscillation frequency and the angular frequency tracked by the phase-locked loop to obtain a fundamental frequency measurement value. The present invention measures the amplitude-frequency modulated signal by adding an improved measurement loop to an existing conventional phase-locked loop, thereby achieving the phase-locked loop's error-free tracking of the actual amplitude and frequency modulated AC signal phase. The present invention can achieve rapid extraction of the amplitude and frequency of the amplitude-frequency modulated signal in a rotating coordinate system, ensure the accuracy of the amplitude-frequency modulated signal measurement method based on the phase-locked loop, and thereby achieve rapid analysis and suppression of oscillations in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0030] Figure 1 A schematic diagram of a measurement loop of a phase-locked loop suitable for measuring amplitude-frequency modulated signals in an embodiment of the present invention;

[0031] Figure 2 is a schematic diagram of a frequency domain response characteristic of a conventional phase-locked loop in an embodiment of the present invention;

[0032] Figure 3 A schematic diagram of a voltage measurement deviation before and after a PLL improvement in an embodiment of the present invention;

[0033] Figure 4 This is an FFT analysis of voltage measurement deviation before and after a PLL improvement in an embodiment of the present invention;

[0034] Figure 5 A schematic diagram of the structure of a phase-locked loop suitable for measuring amplitude-frequency modulated signals provided by an embodiment of the present invention;

[0035] Figure 6 A flow chart of a method for measuring an amplitude-frequency modulated signal of a phase-locked loop provided by an embodiment of the present invention;

[0036] Figure 7 A schematic diagram of a computer device entity structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0037] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0038] In order to facilitate understanding of the technical solution provided by this application, the relevant contents of the technical solution of this application are first explained below.

[0039] In one embodiment, Figure 1 FIG. 1 is a schematic diagram of a measurement loop of a phase-locked loop suitable for measuring amplitude-frequency modulated signals according to an embodiment of the present invention. Figure 1 Taking the typical phase-locked loop shown in the blue frame as an example, the existing phase-locked loop structure workflow is as follows:

[0040] Collect three-phase voltage signals, perform dq coordinate transformation on the three-phase voltage signals to obtain ud and uq, calculate uq by kp to obtain a first value, calculate uq by ki and perform 1 / s integration to calculate a second value, add the first value and the second value to obtain a third value, and compare the third value with the power frequency angular velocity ω n Add together to get the angular frequency ω p ll .

[0041] In one embodiment, the angular frequency disturbance to angular frequency response transfer function G(s) is obtained according to the PLL linearization model:

[0042]

[0043] Among them, s is the integration operator, k i is the integration coefficient, k p is the integration coefficient, U pu It is the per unit value of the voltage amplitude to be measured.

[0044] Draw its amplitude-frequency and phase-frequency characteristic curves, such as Figure 2 The figure shows a schematic diagram of the frequency domain response characteristics of a conventional phase-locked loop in an embodiment of the present invention. It can be seen that, except for the extremely low frequency band close to the DC quantity, the amplitude gain |G(jω1)| in other frequency bands increases or decreases, and the phase response ∠G(jω1) gradually increases in hysteresis value. Therefore, the existing conventional phase-locked loop has a phase tracking error.

[0045] In order to solve the above technical problems, Figure 5As shown, an embodiment of the present invention provides a phase-locked loop suitable for measuring amplitude-frequency modulated signals, comprising:

[0046] A delayed phase correction module is used to perform delayed phase correction on the three-phase voltage signal to obtain a correction value;

[0047] An FFT measurement module is used to perform FFT measurement on the correction value to obtain an oscillation frequency;

[0048] The fundamental frequency measurement module is used to perform average processing on the oscillation frequency and the angular frequency tracked by the phase-locked loop to obtain a fundamental frequency measurement value.

[0049] In one embodiment, Figure 1 As shown in the red frame, the workflow of improving the phase-locked loop structure is as follows:

[0050] The collected three-phase voltage signal u abc_pu The delayed phase correction module performs delayed phase correction to obtain a correction value (the fourth value), and the correction value is measured by the FFT measurement module to obtain the oscillation frequency ω 1m ; Oscillation frequency ω 1m and the angular frequency ω tracked by the phase-locked loop pll The fundamental frequency measurement value ω is obtained by averaging the fundamental frequency through the fundamental frequency measurement module. 0m .

[0051] Specifically, for AC signals with actual amplitude and frequency modulation, in order to accurately measure the fundamental frequency ω 0m Without being disturbed by the modulation signal, the angular frequency ω tracked by the phase-locked loop pll An average value filter is added to perform average value filtering to obtain the fundamental frequency measurement value.

[0052] The present invention measures the amplitude-frequency modulated signal by adding an improved measurement loop to the existing conventional phase-locked loop, thereby realizing the phase-locked loop to track the actual amplitude and frequency modulated AC signal phase without difference. The present invention can realize the rapid extraction of the amplitude and frequency of the amplitude-frequency modulated signal in the rotating coordinate system, ensure the accuracy of the amplitude-frequency modulated signal measurement method based on the phase-locked loop, and then realize the rapid analysis and suppression of oscillation in engineering.

[0053] In one embodiment, it further includes:

[0054] The frequency modulation signal measurement module is used to perform amplitude gain compensation on the difference between the fundamental frequency and the angular frequency to obtain a frequency modulation signal measurement value.

[0055] Specifically, the analytical expression of amplitude-frequency modulation excitation in the rectangular coordinate system is:

[0056]

[0057] in:

[0058]

[0059] In the formula, a1 represents the frequency modulation signal, ω0 is the system power frequency, ω1 is the frequency of the amplitude modulation signal and the frequency modulation signal, and They represent the initial phases of the amplitude modulation signal and the frequency modulation signal respectively, U0 represents the initial voltage of the node, A1 and U1 represent the frequency modulation index and the amplitude modulation index respectively.

[0060] From the above formula, we can see that

[0061] Therefore, by measuring A1 and The value of a1 is obtained.

[0062] In one embodiment, the amplitude gain compensation and phase correction are used to obtain the accurate frequency modulation index A1 and the initial phase of the amplitude modulation signal. The amplitude gain compensation link is composed of 1 / |G(jω 1m )|. Phase compensation is achieved by Figure 1 Middle delay link -τs The time constant τ is determined by the oscillation frequency ω 1m And the phase lag value is determined, which is calculated by the following formula:

[0063]

[0064] In one embodiment, the phase-locked loop tracks the angular frequency ω pll - Fundamental frequency measurement value ω 0m = the fifth value, the fifth value is obtained through the amplitude gain compensation link to obtain the frequency modulation signal measurement a 1m .

[0065] In one embodiment, it further includes:

[0066] The amplitude modulation signal measurement module is used to perform integration calculation on the fundamental frequency measurement value and the frequency modulation signal measurement value, and then perform dq coordinate transformation to obtain the amplitude modulation signal measurement value.

[0067] In one embodiment, the fundamental frequency measurement value ω 0m After being processed by the delayed phase correction module and the frequency modulation signal measurement value a 1m Add them together, and then perform 1 / s integration to get the speed ω m The phase angle during rotation is then transformed into the dq coordinate to obtain the amplitude modulated signal measurement value U m .

[0068] In one embodiment, the dq coordinate transformation adopts the following formula:

[0069]

[0070] Where ω1 is the frequency of the amplitude modulation signal and the frequency modulation signal, and They represent the initial phases of the amplitude modulation signal and the frequency modulation signal respectively, U0 represents the initial voltage of the node, A1 and U1 represent the frequency modulation index and the amplitude modulation index respectively.

[0071] In one embodiment, the fundamental frequency ω 0m The sixth value is obtained through the delayed phase correction link, and the sixth value is measured with the frequency modulation signal a 1m The seventh value is obtained by adding the seventh value, the eighth value is obtained by 1 / s integration, and the eighth value and the fourth value are transformed by a preset dq coordinate to obtain the amplitude modulation signal measurement value U m .

[0072] The present invention measures the amplitude-frequency modulated signal by adding an improved measurement loop to the existing conventional phase-locked loop, thereby realizing the phase-locked loop to track the actual amplitude and frequency modulated AC signal phase without difference. The present invention can realize the rapid extraction of the amplitude and frequency of the amplitude-frequency modulated signal in the rotating coordinate system, ensure the accuracy of the amplitude-frequency modulated signal measurement method based on the phase-locked loop, and then realize the rapid analysis and suppression of oscillation in engineering.

[0073] The present invention builds a simulation model in a laboratory and uses some typical working conditions to verify the decomposition effects of the amplitude modulation signal and the frequency modulation signal of the field data.

[0074] like Figure 3 The figure shows a schematic diagram of voltage measurement deviation before and after PLL improvement in an embodiment of the present invention, 1-2s before is before PLL improvement, and 2-3s after PLL improvement. Figure 3 The waveform shown in the figure is analyzed by FFT. The result is as follows Figure 4 shown.

[0075] Figure 3 This shows that the interpolation between the instantaneous value and the measured value becomes smaller after the phase-locked loop is improved. Figure 4 The analysis results show that the measurement deviation is significantly reduced after the PLL is improved, and the voltage measurement deviation is reduced by about 4.5 times.

[0076] Combined with the above analysis, the amplitude-frequency modulation signal measurement method based on the improved phase-locked loop can accurately extract the oscillation information.

[0077] Based on the same inventive idea, Figure 6As shown, the embodiment of the present invention further provides a working method of a phase-locked loop suitable for measuring an amplitude-frequency modulated signal, comprising:

[0078] Performing delayed phase correction on the three-phase voltage signal to obtain a correction value;

[0079] Performing FFT measurement on the correction value to obtain the oscillation frequency;

[0080] The oscillation frequency and the angular frequency tracked by the phase-locked loop are averaged to obtain a fundamental frequency measurement value.

[0081] In one embodiment, the method further includes: performing amplitude gain compensation on the difference between the fundamental frequency and the angular frequency to obtain a frequency modulation signal measurement value.

[0082] In one embodiment, the method further includes: integrating the fundamental frequency measurement value and the frequency modulation signal measurement value, and then performing dq coordinate transformation to obtain the amplitude modulation signal measurement value.

[0083] In one embodiment, the fundamental frequency measurement value is processed by the delayed phase correction module and then added to the frequency modulation signal measurement value, and then an integral calculation is performed, and then a dq coordinate transformation is performed to obtain the amplitude modulation signal measurement value.

[0084] In one embodiment, the dq coordinate transformation adopts the following formula:

[0085]

[0086] Where ω1 is the frequency of the amplitude / frequency modulation signal, and They represent the initial phases of the amplitude modulation signal and the frequency modulation signal respectively, U0 represents the initial voltage of the node, A1 and U1 represent the frequency modulation index and the amplitude modulation index respectively.

[0087] It is worth noting that the method embodiments of the present invention and the aforementioned virtual device embodiments can be implemented one-to-one, and will not be described in detail herein.

[0088] like Figure 7 As shown, a computer device provided by an embodiment of the present invention includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements any of the above methods when executing the computer program.

[0089] An embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, any of the above methods is implemented.

[0090] An embodiment of the present invention provides a computer program product, which includes a computer program. When the computer program is executed by a processor, any of the above methods is implemented.

[0091] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, 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 code.

[0092] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0093] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0094] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0095] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A phase-locked loop suitable for measuring amplitude-frequency modulated signals, characterized in that: include: A delayed phase correction module is used to perform delayed phase correction on the three-phase voltage signal to obtain a correction value; An FFT measurement module, used for performing FFT measurement on the correction value to obtain an oscillation frequency; The fundamental frequency measurement module is used to perform average processing on the oscillation frequency and the angular frequency tracked by the phase-locked loop to obtain a fundamental frequency measurement value.

2. The phase-locked loop according to claim 1, characterized in that: Also includes: The frequency modulation signal measurement module is used to perform amplitude gain compensation on the difference between the fundamental frequency and the angular frequency to obtain a frequency modulation signal measurement value.

3. The phase-locked loop according to claim 2, characterized in that: Also includes: The amplitude modulation signal measurement module is used to perform integration calculation on the fundamental frequency measurement value and the frequency modulation signal measurement value, and then perform dq coordinate transformation to obtain the amplitude modulation signal measurement value.

4. The phase-locked loop according to claim 3, characterized in that: The fundamental frequency measurement value is processed by the delayed phase correction module and then added to the frequency modulation signal measurement value, and then an integral calculation is performed, and then a dq coordinate transformation is performed to obtain the amplitude modulation signal measurement value.

5. The phase-locked loop according to claim 3 or 4, characterized in that: The dq coordinate transformation adopts the following formula: Where ω1 is the frequency of the amplitude / frequency modulation signal, and They represent the initial phases of the amplitude modulation signal and the frequency modulation signal respectively, U0 represents the initial voltage of the node, A1 and U1 represent the frequency modulation index and the amplitude modulation index respectively.

6. A method for operating a phase-locked loop for measuring amplitude-frequency modulated signals, characterized in that: include: Performing delayed phase correction on the three-phase voltage signal to obtain a correction value; Performing FFT measurement on the correction value to obtain the oscillation frequency; The oscillation frequency and the angular frequency tracked by the phase-locked loop are averaged to obtain a fundamental frequency measurement value.

7. The method according to claim 6, characterized in that Also includes: Amplitude gain compensation is performed on the difference between the fundamental frequency and the angular frequency to obtain a frequency modulation signal measurement value.

8. The method according to claim 7, characterized in that: Also includes: After the fundamental frequency measurement value and the frequency modulation signal measurement value are integrated and calculated, a dq coordinate transformation is performed to obtain the amplitude modulation signal measurement value.

9. The method according to claim 8, characterized in that The fundamental frequency measurement value is processed by the delayed phase correction module and then added to the frequency modulation signal measurement value, and then an integral calculation is performed, and then a dq coordinate transformation is performed to obtain the amplitude modulation signal measurement value.

10. The method according to claim 8 or 9, characterized in that: The dq coordinate transformation adopts the following formula: Where ω1 is the frequency of the amplitude modulation signal and the frequency modulation signal, and They represent the initial phases of the amplitude modulation signal and the frequency modulation signal respectively, U0 represents the initial voltage of the node, A1 and U1 represent the frequency modulation index and the amplitude modulation index respectively.

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