Primary frequency modulation test method and system based on voltage frequency source

Abstract

The invention belongs to the technical field of power system regulation and control, and particularly relates to a primary frequency modulation test method and system based on a voltage frequency source, and the method comprises the steps: obtaining the power frequency rated voltage and rated frequency of the voltage frequency source; performing Fourier transform on the real-time measurement voltage of the voltage frequency source to obtain a measurement frequency; resampling the real-time measured voltage according to the obtained measurement frequency and the rated frequency to obtain the voltage amplitude, the voltage phase and the voltage frequency of the voltage frequency source; and correcting and feeding back the obtained voltage amplitude, the voltage phase and the voltage frequency, and when and only when the voltage amplitude, the voltage phase and the voltage frequency all meet preset requirements, outputting the voltage amplitude, the voltage phase and the voltage frequency meeting the requirements, thereby completing the primary frequency modulation test based on the voltage frequency source.

Description

Technical Field

[0001] The present invention belongs to the technical field of power system control, and in particular relates to a primary frequency modulation test method and system based on a voltage frequency source. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the gradual advancement of the construction of new power systems, the construction of power system source-grid-load-storage systems has gradually emerged. The source-grid-load-storage system is an operating model that includes an overall solution of "power source, power grid, load, and energy storage". It can accurately control the interruptible power load and energy storage resources of the society, improve the safe operation level of the power grid, and solve the problems of power grid volatility in the process of clean energy consumption. The research and application of the source-grid-load-storage system is of great significance to energy development: first, it improves the ability to respond to large power grid faults, which can shorten the emergency handling time of large power grid faults from minutes to milliseconds, providing professional means for preventing and controlling large-scale power outages; second, it supports the development of distributed power sources, effectively reduces peak loads by accurately controlling millisecond-level interruptible loads, effectively suppresses power grid fluctuations caused by large-scale photovoltaic and wind power generation, and helps clean energy consumption; third, it promotes the development of emerging industries. The source-grid-load-storage system widely uses new generation power system automatic control, artificial intelligence, wireless communication and other technologies, which can effectively promote the development of emerging industries such as energy storage and communications.

[0004] In order to achieve rapid power regulation of source, grid, load and storage, new energy power stations are generally equipped with rapid power control devices, which have the function of rapid active power regulation. Within the system's active power regulation capability, the system's active power can be adjusted quickly and in real time according to the regulation instructions. The system's active power can be adjusted according to the system's frequency.

[0005] After a fault occurs, the fast power control device can respond quickly and adjust according to the operating status of wind, solar and storage. However, in the actual operation of the fast power control device, it is difficult to test the regulation ability of the whole system in an offline state without the existence of relevant loads, and it is difficult for the power grid to reduce frequency, so its regulation ability cannot be verified. Therefore, the virtual system frequency is generally used to carry out a frequency regulation test on the entire power grid, such as Figure 1 As shown, a frequency signal generating device is needed to simulate the operating conditions of system frequency changes. In order to achieve the ability to adjust the system frequency changes, the frequency signal generating device has very high requirements on the frequency accuracy and capability of the voltage output. Ordinary voltage signal sources are difficult to meet the test requirements of frequency accuracy, and also do not have the ability to simulate the frequency changes of actual operating conditions.

[0006] The existing primary frequency modulation test technology based on voltage frequency source generally has the following problems:

[0007] (1) Since the voltage source of the relay protection tester is a relay protection device, its accuracy requirement is not high and it is basically open-loop control. The main purpose is to achieve the transient capability of the voltage output;

[0008] (2) The voltage source of the electric energy meter tester has high requirements on the accuracy of the voltage source. It adopts closed-loop control and collects the output voltage for slow adjustment control. It lacks the transient voltage regulation capability of voltage-frequency conversion. Summary of the invention

[0009] In order to solve the above problems, the present invention proposes a primary frequency modulation test method and system based on a voltage-frequency source, which is based on closed-loop control and adopts a phase modulation method to achieve a smooth transition of frequency changes and realize feedback control of voltage and frequency.

[0010] According to some embodiments, a first solution of the present invention provides a primary frequency modulation test method based on a voltage frequency source, which adopts the following technical solution:

[0011] A primary frequency modulation test method based on a voltage frequency source, comprising:

[0012] Obtain the rated power frequency voltage and rated frequency of the voltage and frequency source;

[0013] Performing Fourier transform on the real-time measured voltage of the voltage frequency source to obtain the measured frequency;

[0014] According to the obtained measurement frequency and rated frequency, the real-time measurement voltage is resampled to obtain the voltage amplitude, voltage phase and voltage frequency of the voltage frequency source;

[0015] The obtained voltage amplitude, voltage phase and voltage frequency are corrected and fed back. When and only when the voltage amplitude, voltage phase and voltage frequency meet the preset requirements, the voltage amplitude, voltage phase and voltage frequency that meet the requirements are output to complete a frequency modulation test based on the voltage-frequency source.

[0016] As a further technical limitation, the voltage frequency test includes at least a steady-state test, a dead-zone scan test and a frequency step test; in the dead-zone scan test, a steady-state frequency increasing and decreasing frequency sweeping method is adopted; in the frequency step test, a state sequence method is adopted to change the voltage and obtain a frequency step signal.

[0017] As a further technical limitation, in the process of correcting and feeding back the obtained voltage amplitude, voltage phase and voltage frequency, it is determined whether the voltage amplitude and voltage phase obtained after resampling meet the preset requirements. If so, feedback correction of the voltage frequency is performed; otherwise, the voltage amplitude and voltage phase are corrected and the rated voltage of the industrial frequency is obtained again.

[0018] Furthermore, in the process of voltage frequency feedback correction, it is determined whether the voltage frequency obtained after resampling meets the preset requirements. If so, the voltage amplitude, voltage phase and voltage frequency that meet the requirements are output to complete the correction. Otherwise, the voltage frequency is corrected and the rated voltage of the industrial frequency is obtained again.

[0019] As a further technical limitation, when the voltage frequency changes, the voltage waveform becomes discontinuous, and the obtained voltage frequency test result becomes erroneous.

[0020] Furthermore, a smooth transition of the voltage frequency when the voltage frequency changes is achieved by phase modulation.

[0021] According to some embodiments, a second solution of the present invention provides a primary frequency modulation test system based on a voltage frequency source, which adopts the following technical solution:

[0022] A primary frequency modulation test system based on a voltage frequency source, comprising:

[0023] An acquisition module, configured to acquire a rated power frequency voltage and a rated frequency of a voltage and frequency source;

[0024] A transformation module, configured to perform Fourier transformation on the real-time measured voltage of the voltage-frequency source to obtain a measured frequency;

[0025] A sampling module is configured to resample the real-time measured voltage according to the obtained measured frequency and rated frequency to obtain the voltage amplitude, voltage phase and voltage frequency of the voltage-frequency source;

[0026] The test module is configured to correct and feedback the obtained voltage amplitude, voltage phase and voltage frequency. If and only if the voltage amplitude, voltage phase and voltage frequency meet the preset requirements, the voltage amplitude, voltage phase and voltage frequency that meet the requirements are output to complete a frequency modulation test based on the voltage-frequency source.

[0027] According to some embodiments, a third solution of the present invention provides a computer-readable storage medium, which adopts the following technical solution:

[0028] A computer-readable storage medium stores a program, which, when executed by a processor, implements the steps of a primary frequency modulation test method based on a voltage-frequency source as described in the first solution of the present invention.

[0029] According to some embodiments, a fourth solution of the present invention provides an electronic device, which adopts the following technical solution:

[0030] An electronic device comprises a memory, a processor and a program stored in the memory and running on the processor. When the processor executes the program, the steps in the primary frequency modulation test method based on a voltage frequency source as described in the first solution of the present invention are implemented.

[0031] According to some embodiments, a fifth solution of the present invention provides a computer program product, which adopts the following technical solution:

[0032] A computer program product includes software codes, wherein the program in the software codes executes the steps in the primary frequency modulation test method based on a voltage-frequency source as described in the first solution of the present invention.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention adopts a linear power amplifier and cooperates with a voltage recovery loop to realize the correction of the voltage output signal, thereby improving the output accuracy of the voltage; adopts a phase tracking iterative frequency calculation method to greatly improve the calculation speed and calculation accuracy of the frequency; adopts a secondary resampling method to recalculate the amplitude and phase of the output voltage according to the precise frequency, thereby improving the output accuracy of the voltage; in order to prevent the discontinuity of the waveform when the frequency changes, which causes the frequency to be output incorrectly during the change process, a frequency differential followed by phase modulation is adopted to realize the frequency change so as to achieve the continuity of the frequency output. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0036] Figure 1 It is a schematic diagram of a primary frequency modulation test based on a voltage frequency source in the background technology of the present invention;

[0037] Figure 2 This is a structural diagram of a primary frequency modulation test method based on a voltage frequency source in Embodiment 1 of the present invention;

[0038] Figure 3 This is a flow chart of a primary frequency modulation test method based on a voltage frequency source in Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0040] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0041] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] In the present invention, terms such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "side", "bottom", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention, and do not specifically refer to any part or element in the present invention and should not be understood as limitations on the present invention.

[0043] In the present invention, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be fixedly connected, integrally connected or detachably connected; it can be directly connected or indirectly connected through an intermediate medium. For relevant scientific research or technical personnel in this field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances, and they cannot be understood as limitations on the present invention.

[0044] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0045] Embodiment 1

[0046] Embodiment 1 of the present invention introduces a primary frequency modulation test method based on a voltage frequency source.

[0047] The primary frequency modulation test method based on the voltage frequency source in this embodiment adopts the following method: Figure 2The architecture diagram shown includes a recovery system consisting of a host computer, a ZYNQ dual-core CPU system, a DA conversion module, a Chebyshev active second-order filter circuit, a power amplifier module, a secondary conversion PT and an AD conversion module; among them, the host computer generates test data, the ZYNQ dual-core CPU system is responsible for the external interface and data interaction with the host computer, the DA conversion module is responsible for converting discrete digital signals into analog small voltage signals, the Chebyshev active second-order filter system is responsible for filtering out the high-frequency signals generated by the digital signal process, the power amplifier module is responsible for proportionally amplifying the small voltage signal into a secondary voltage signal with power output, and the secondary conversion PT and AD conversion module are responsible for recovering the output voltage signal.

[0048] As one or more implementation methods, this embodiment adopts Xilinx's ZYNQ 7020 chip, which is a dual-processor architecture of FPGA+ARM, and adopts a high constant temperature crystal oscillator (OCXO) as the clock of the entire system, with a frequency accuracy level of up to 5ppm; at the same time, the FPGA virtual sampling clock is used to accurately control the sampling time of the AD and DA chips. The DA conversion module adopts ADI's AD5764CSUZ 4-channel 16-bit DA chip, with a signal output range of ±10V. According to the frequency and accuracy curve of the chip, a sampling output frequency of 20kHz is selected, which can meet the accuracy of the output small voltage and reduce the superposition of high-frequency signals caused by discrete errors. The AD conversion module adopts AD7606 8-channel synchronous sampling 16-bit AD chip, with a maximum sampling rate of 200k (this embodiment adopts a 50k sampling rate).

[0049] As one or more implementation methods, the filter circuit in this embodiment adopts Chebyshev active second-order filtering. The Chebyshev active second-order filtering circuit has the characteristic of rapid attenuation of high-frequency signals. At the same time, active filtering increases the driving ability of DA conversion to prevent waveform distortion caused by load capacity problems from affecting the amplification characteristics. The cutoff frequency of RC is selected as 3kHz, which can ensure that high-frequency signals are filtered out and that the attenuation of the fundamental signal does not affect the output accuracy of the voltage. The power amplifier module adopts a linear power amplifier, and the proportional relationship between R1 and R2 is used to control the amplification factor of the output voltage. The secondary conversion PT adopts a 0.05-level electromagnetic voltage transformer with a conversion ratio of 100 / 2.

[0050] It should be noted that the factors affecting the frequency accuracy of the voltage frequency source in this embodiment include: the truncation calculation error when output to the DA module after discretization, the crystal oscillator error generated when the DA module converts the discrete digital quantity into an analog quantity, the phase error caused by the high-frequency signal, and the phase offset caused by the stray capacitance inside the power amplifier module.

[0051] In order to improve the output frequency accuracy of the voltage frequency source, this embodiment uses Chebyshev active second-order filtering to solve the phase error caused by the high-frequency signal generated in the process of converting the discrete digital quantity of the DA module into the analog quantity; other influencing factors can only be realized in the software by relying on the secondary voltage recovery. The host computer is implemented on the PC side, based on the cross-platform QT, winpcap network programming library and Lua scripting language development, and will design a friendly user interface and provide rich functional modules.

[0052] like Figure 3 As shown, the primary frequency modulation test method based on a voltage frequency source introduced in this embodiment includes the following steps:

[0053] Step 1: Output rated power frequency voltage;

[0054] Step 2: Voltage recovery;

[0055] Step 3: Voltage correction;

[0056] Step 4: Frequency correction;

[0057] Step 5: Functional test output.

[0058] As one or more implementation modes, in step 1, the rated power frequency voltage of the voltage frequency source is obtained and output, and the obtained rated power frequency voltage is discretized; that is, the discretized rated power frequency voltage X(n) is Among them, U N is the rated voltage amplitude; f N is the rated frequency; t n is the sampling time corresponding to the n sampling point; is the angle correction value, initially 0; k1 is the amplitude correction coefficient, initially 1.

[0059] As one or more implementation methods, in step 2, the frequency value of the discrete industrial frequency rated voltage is calculated by Fourier transform, and the identity equation is obtained. The actual frequency is f, assuming the rated frequency is f0.

[0060] It should be noted that if the real parts of two consecutive calculations are close, the frequency value may have a large error. Therefore, according to the geometric theorem, it can be optimized as The value of M is 1 / 8 cycle sampling points.

[0061] To improve the frequency measurement algorithm, the original sampled data is resampled twice according to the measurement frequency, and the above frequency measurement calculation is repeated. The calculated frequency is compared with the last assumed rated frequency. If the error between the two is less than the ideal error value, the calculated frequency is considered to be the true frequency value; otherwise, the above steps are repeated iteratively using the current calculated frequency as the assumed rated frequency (normally, the frequency error can be <0.0001Hz for about 6 times). According to the calculated true frequency, the three-phase voltage is resampled twice at the rated frequency and then Fourier integral transform is performed to obtain the accurate voltage amplitude and phase value.

[0062] As one or more implementation methods, in step three, the obtained voltage amplitude and voltage phase are compared with the amplitude and phase of the obtained rated power frequency voltage, and the voltage amplitude and voltage phase are adjusted and corrected in combination with the discretization formula, that is, k1 is adjusted according to the amplitude error, and k2 is adjusted according to the phase error.

[0063] As one or more implementation modes, in step four, after the amplitude and phase meet the accuracy level requirements, there is still an error in the frequency. At this time, the software controls the sampling clock signal through the FPGA core in the ZYNQ chip to correct the slight frequency error to meet the high-precision frequency requirements.

[0064] As one or more implementation methods, in step 5, the voltage amplitude, phase, and frequency are corrected in the steady state and then tested and outputted; specifically:

[0065] (1) The dead zone scanning test is implemented by using a steady-state frequency increase and decrease sweep method, with Hz / S as the unit for slow frequency adjustment;

[0066] (2) The state sequence method is used to achieve rapid frequency changes during frequency step testing;

[0067] It should be noted that in order to prevent the discontinuity of the waveform when the frequency changes, which may cause the frequency to be output incorrectly during the change process, the frequency change adopts a phase modulation method to achieve the frequency change so as to achieve a smooth transition of the frequency; that is, Among them, X S is the effective amplitude; f is the frequency; is the frequency change rate; n is the sampling number; t n is the sampling time corresponding to the n sampling point;

[0068] (3) In the frequency perturbation experiment, a script is used to read the frequency of each time node, and the initial phase angle is superimposed when switching between frequencies to achieve frequency continuity;

[0069] (4) In the voltage disturbance experiment, the voltage is suddenly changed by using the state sequence method.

[0070] This embodiment uses a linear power amplifier and cooperates with a voltage recovery loop to realize the correction of the voltage output signal, thereby improving the output accuracy of the voltage; a phase tracking iterative frequency calculation method is used to greatly improve the frequency calculation speed and calculation accuracy; a secondary resampling method is used to recalculate the amplitude and phase of the output voltage according to the precise frequency, thereby improving the output accuracy of the voltage; in order to prevent the discontinuity of the waveform when the frequency changes, which causes the frequency to be erroneously output during the change process, a frequency differentiation followed by phase adjustment is used to realize the frequency change so as to achieve the continuity of the frequency output.

[0071] Embodiment 2

[0072] Embodiment 2 of the present invention introduces a primary frequency modulation test system based on a voltage frequency source.

[0073] A primary frequency modulation test system based on a voltage frequency source, comprising:

[0074] An acquisition module, configured to acquire a rated power frequency voltage and a rated frequency of a voltage and frequency source;

[0075] A transformation module, configured to perform Fourier transformation on the real-time measured voltage of the voltage-frequency source to obtain a measured frequency;

[0076] A sampling module is configured to resample the real-time measured voltage according to the obtained measured frequency and rated frequency to obtain the voltage amplitude, voltage phase and voltage frequency of the voltage-frequency source;

[0077] The test module is configured to correct and feedback the obtained voltage amplitude, voltage phase and voltage frequency. If and only if the voltage amplitude, voltage phase and voltage frequency meet the preset requirements, the voltage amplitude, voltage phase and voltage frequency that meet the requirements are output to complete a frequency modulation test based on the voltage-frequency source.

[0078] The detailed steps are the same as the primary frequency modulation test method based on the voltage frequency source provided in Example 1, and will not be repeated here.

[0079] Embodiment 3

[0080] Embodiment 3 of the present invention provides a computer-readable storage medium.

[0081] A computer-readable storage medium stores a program, which, when executed by a processor, implements the steps of the primary frequency modulation test method based on a voltage-frequency source as described in the first embodiment of the present invention.

[0082] The detailed steps are the same as the primary frequency modulation test method based on the voltage frequency source provided in Example 1, and will not be repeated here.

[0083] Embodiment 4

[0084] A fourth embodiment of the present invention provides an electronic device.

[0085] An electronic device comprises a memory, a processor and a program stored in the memory and running on the processor, wherein when the processor executes the program, the steps in the primary frequency modulation test method based on a voltage frequency source as described in the first embodiment of the present invention are implemented.

[0086] The detailed steps are the same as the primary frequency modulation test method based on the voltage frequency source provided in Example 1, and will not be repeated here.

[0087] Embodiment 5

[0088] Embodiment 5 of the present invention provides a computer program product.

[0089] A computer program product includes software codes, wherein the program in the software codes executes the steps in the primary frequency modulation test method based on a voltage-frequency source as described in the first embodiment of the present invention.

[0090] The detailed steps are the same as the primary frequency modulation test method based on the voltage frequency source provided in Example 1, and will not be repeated here.

[0091] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A primary frequency modulation test method based on a voltage frequency source, characterized in that: include: Obtain the rated power frequency voltage and rated frequency of the voltage and frequency source; Performing Fourier transform on the real-time measured voltage of the voltage frequency source to obtain the measured frequency; According to the obtained measurement frequency and rated frequency, the real-time measurement voltage is resampled to obtain the voltage amplitude, voltage phase and voltage frequency of the voltage frequency source; The obtained voltage amplitude, voltage phase and voltage frequency are corrected and fed back. When and only when the voltage amplitude, voltage phase and voltage frequency meet the preset requirements, the voltage amplitude, voltage phase and voltage frequency that meet the requirements are output to complete a frequency modulation test based on the voltage-frequency source.

2. A primary frequency modulation test method based on a voltage frequency source as claimed in claim 1, characterized in that: The voltage frequency test includes at least a steady-state test, a dead-zone scan test and a frequency step test; in the dead-zone scan test, a steady-state frequency increasing and decreasing frequency sweeping method is adopted; in the frequency step test, a state sequence method is adopted to change the voltage to obtain a frequency step signal.

3. A primary frequency modulation test method based on a voltage frequency source as claimed in claim 1, characterized in that: In the process of correcting and feeding back the obtained voltage amplitude, voltage phase and voltage frequency, it is determined whether the voltage amplitude and voltage phase obtained after resampling meet the preset requirements. If so, feedback correction of the voltage frequency is performed; otherwise, the voltage amplitude and voltage phase are corrected and the rated voltage of the power frequency is obtained again.

4. A primary frequency modulation test method based on a voltage frequency source as claimed in claim 3, characterized in that: During the voltage frequency feedback correction process, it is determined whether the voltage frequency obtained after resampling meets the preset requirements. If so, the voltage amplitude, voltage phase and voltage frequency that meet the requirements are output to complete the correction. Otherwise, the voltage frequency is corrected and the rated voltage of the power frequency is obtained again.

5. A primary frequency modulation test method based on a voltage frequency source as claimed in claim 1, characterized in that: When the voltage frequency changes, the voltage waveform becomes discontinuous, and the voltage frequency test result obtained is erroneous.

6. A primary frequency modulation test method based on a voltage frequency source as claimed in claim 5, characterized in that: The phase modulation method is used to achieve a smooth transition of voltage frequency when the voltage frequency changes.

7. A primary frequency modulation test system based on a voltage frequency source, characterized in that: include: An acquisition module, configured to acquire a rated power frequency voltage and a rated frequency of a voltage and frequency source; A transformation module, configured to perform Fourier transformation on the real-time measured voltage of the voltage-frequency source to obtain a measured frequency; A sampling module is configured to resample the real-time measured voltage according to the obtained measured frequency and rated frequency to obtain the voltage amplitude, voltage phase and voltage frequency of the voltage-frequency source; The test module is configured to correct and feedback the obtained voltage amplitude, voltage phase and voltage frequency. If and only if the voltage amplitude, voltage phase and voltage frequency meet the preset requirements, the voltage amplitude, voltage phase and voltage frequency that meet the requirements are output to complete a frequency modulation test based on the voltage-frequency source.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the primary frequency modulation test method based on a voltage-frequency source as described in any one of claims 1 to 6 are implemented.

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 program, the steps of the primary frequency modulation test method based on a voltage-frequency source as described in any one of claims 1-6 are implemented.

10. A computer program product comprising software code, characterized in that The program in the software code executes the steps of the primary frequency modulation test method based on a voltage-frequency source as described in any one of claims 1-6.

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