A voltage-excited method, apparatus, and system for testing the oscillation of wind turbine generators.

Abstract

This invention provides a voltage-excited method, apparatus, and system for testing the oscillation of wind turbine generators. The voltage-excited method includes: controlling a power converter in a grid-connected testing device to generate a voltage excitation signal to the wind turbine generator; acquiring generator speed vectors within the disturbance frequency range of the wind turbine generator; determining speed deviation indices at each disturbance frequency based on the generator speed vectors at each disturbance frequency; and determining the target oscillation mode frequency of the wind turbine generator based on comparisons between the speed deviation indices at each disturbance frequency and preset thresholds, and comparisons between the speed deviation indices at the corresponding previous disturbance frequency and preset thresholds. This invention can quickly and effectively identify the oscillation modes of wind turbine generators, significantly improving testing efficiency and reducing testing costs.

Description

Technical Field

[0001] This invention relates to the field of wind turbine vibration testing technology, specifically to a method, apparatus, and system for testing wind turbine vibration based on voltage excitation. Background Technology

[0002] With the increasing penetration rate of wind power, the dynamic processes of wind turbines and their interaction with the power grid have attracted widespread attention. One difference between doubly-fed induction generator (DFIG) wind turbines and conventional synchronous generators is the presence of a gearbox between the prime mover shaft and the generator shaft for speed transmission. Therefore, the flexibility of the shaft system is much greater than that of a synchronous generator, making it more prone to low-frequency oscillations (ranging from 0.1Hz to 10Hz) during dynamic operation. These low-frequency oscillations not only affect the operational safety and lifespan of the turbine equipment, but also, in power systems with a high proportion of renewable energy, the similarity in low-frequency oscillation frequencies exhibited by turbines can threaten the safe operation of the power grid. Therefore, accurately calculating or measuring the low-frequency oscillation modes of grid-connected DFIG wind turbines and, based on this, managing the risk of low-frequency oscillations in the wind power collection area at the system level is of great significance.

[0003] Currently, there are three main methods for analyzing the low-frequency oscillation modes of doubly-fed induction generator (DFIG) wind turbines: theoretical calculation, model simulation, and field testing. These methods suffer from several problems: First, theoretical calculations of DFIG shaft oscillation modes are currently only applicable to the classic two-mass shaft model of DFIGs based on design parameters, without considering changes in equipment condition due to installation conditions and aging wear during actual operation. Second, simulation software such as Bladed is used to calculate DFIG oscillation modes, but due to differences between digital simulation and actual engineering conditions, the oscillation modes obtained using this method have limited practical guidance. Third, field testing methods involve placing vibration measurement units on various components of the turbine and conducting tests through impact or wind-induced excitation. However, the testing process involves many uncertainties, making it difficult to extract effective information from the measurement results, which is detrimental to subsequent oscillation mode analysis and verification of suppression measures. Therefore, there is currently a lack of a practical and feasible testing method and system that accurately reflects the low-frequency oscillation modes of DFIG wind turbines connected to the grid. Summary of the Invention

[0004] The main objective of this invention is to provide a voltage-excited wind turbine oscillation testing method, apparatus, and system to quickly and effectively identify the oscillation modes of wind turbines, significantly improve testing efficiency, and reduce testing costs.

[0005] To achieve the above objectives, embodiments of the present invention provide a method for testing the oscillation of wind turbine generators based on voltage excitation, comprising:

[0006] The power converter in the grid-connected test device is controlled to generate a voltage excitation signal to the wind turbine.

[0007] Collect the generator speed vector within the disturbance frequency range of the wind turbine;

[0008] The speed deviation index at each disturbance frequency is determined based on the generator speed vector at each disturbance frequency.

[0009] The target oscillation mode frequency of the wind turbine is determined by comparing the speed deviation index at each disturbance frequency with the preset threshold and the speed deviation index at the corresponding previous disturbance frequency with the preset threshold.

[0010] In one embodiment, it further includes:

[0011] The target oscillation mode frequency of the wind turbine corresponding to the maximum value of the speed deviation index under the target oscillation mode frequency of each wind turbine is determined as the shaft oscillation mode frequency.

[0012] In one embodiment, determining the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency includes:

[0013] The voltage and current signals of the wind turbine are collected, and the impedance amplitude and impedance phase angle are determined based on the voltage and current signals.

[0014] Determine the smoothness of the positive sequence impedance at the wind turbine terminals based on the impedance amplitude and impedance phase angle.

[0015] When the smoothness of the positive sequence impedance at the wind turbine terminals meets the preset smoothing conditions, the speed deviation index at each disturbance frequency is determined based on the generator speed vector at each disturbance frequency.

[0016] This invention also provides a voltage-excited wind turbine oscillation testing device, comprising:

[0017] The power converter control module is used to control the power converter in the grid-connected test device to generate voltage excitation signals to the wind turbine.

[0018] The generator speed vector module is used to collect the generator speed vector within the disturbance frequency range of the wind turbine.

[0019] The speed deviation index module is used to determine the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency.

[0020] The target oscillation mode frequency module is used to determine the target oscillation mode frequency of the wind turbine based on the comparison results of the speed deviation index at each disturbance frequency with the preset threshold and the comparison results of the speed deviation index at the corresponding previous disturbance frequency with the preset threshold.

[0021] In one embodiment, it further includes:

[0022] The shaft oscillation mode frequency module is used to determine the target oscillation mode frequency of the wind turbine corresponding to the maximum value of the speed deviation index under the target oscillation mode frequency of each wind turbine.

[0023] In one embodiment, the speed deviation index module includes:

[0024] The impedance value determination unit is used to collect the voltage and current signals of the wind turbine and determine the impedance amplitude and impedance phase angle based on the voltage and current signals.

[0025] Positive sequence impedance smoothness unit, used to determine the positive sequence impedance smoothness of the wind turbine terminals based on impedance amplitude and impedance phase angle;

[0026] The speed deviation index unit is used to determine the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency when the smoothness of the positive sequence impedance at the wind turbine terminal meets the preset smoothness conditions.

[0027] This invention also 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, it implements the steps of the voltage-excited wind turbine oscillation test method.

[0028] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the voltage-excited wind turbine oscillation test method.

[0029] This invention also provides a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the voltage-excited wind turbine oscillation test method.

[0030] This invention also provides a voltage-excited wind turbine oscillation testing system, comprising:

[0031] Power grid;

[0032] Wind turbine units;

[0033] A grid-connected testing device, connected to both the power grid and the wind turbine generator, is used to generate a voltage excitation signal to the wind turbine generator; and

[0034] The voltage-excited wind turbine oscillation test device described above is connected to the grid-connected test device.

[0035] The voltage-excited wind turbine oscillation test method, device and system of the present invention first controls the power converter in the grid-connected test device to generate a voltage excitation signal to the wind turbine, and then determines the speed deviation index at each disturbance frequency according to the generator speed vector at each disturbance frequency to determine the target oscillation mode frequency of the wind turbine. This can quickly and effectively identify the oscillation mode of the wind turbine, greatly improve test efficiency and reduce test cost. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of the wind turbine oscillation test method based on voltage excitation in an embodiment of the present invention;

[0038] Figure 2 This is a flowchart of S103 in an embodiment of the present invention;

[0039] Figure 3 This is a structural block diagram of the wind turbine oscillation testing device based on voltage excitation in an embodiment of the present invention;

[0040] Figure 4 This is a schematic block diagram illustrating the system configuration of the electronic device 9600 according to an embodiment of this application.

[0041] Figure 5 This is a schematic diagram of a wind turbine oscillation testing system based on voltage excitation in an embodiment of the present invention;

[0042] Figure 6 This is a schematic diagram of the positive sequence impedance amplitude of the wind turbine generator terminal under test in an embodiment of the present invention;

[0043] Figure 7 This is a schematic diagram of the positive sequence impedance phase angle of the wind turbine generator terminal under test in an embodiment of the present invention;

[0044] Figure 8 This is a schematic diagram of the corresponding waveform of the generator speed in an embodiment of the present invention;

[0045] Figure 9 This is a schematic diagram of the speed deviation index waveform in an embodiment of the present invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Those skilled in the art will recognize that embodiments of the present invention can be implemented as a system, apparatus, device, method, or computer program product. Therefore, this disclosure can be specifically implemented in the following forms: entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0048] With the increasing proportion of new energy sources, the low-frequency oscillation problem of doubly-fed induction generator (DFIG) wind turbines during grid-connected operation has attracted the attention of the power system. Therefore, accurate measurement and in-depth analysis of low-frequency oscillation modes such as shaft torsional vibration of grid-connected DFIG wind turbines are of great significance. This invention proposes a voltage-excited wind turbine oscillation testing method, device, and system, which can safely, accurately, and efficiently measure the oscillation modes of the wind turbine shaft system through field testing even without knowing the relevant parameters of the DFIG wind turbine. This invention connects a grid-connected testing device in series between the doubly-fed induction generator (DFIG) wind turbine generator and the box-type transformer. When the wind turbine operates under specific conditions, the grid-connected testing device generates a small-signal voltage source for low-frequency oscillation mode testing as the test excitation signal. This tests the generator speed, terminal voltage, and current response of the wind turbine generator, thereby identifying the low-frequency oscillation modes of the wind turbine generator. The invention is simple and flexible to operate, with high testing efficiency. It can quickly measure the wind turbine shaft oscillation frequency and other low-frequency oscillation frequencies affecting the grid-connected characteristics of the unit without opening the unit equipment or affecting its normal operation. Furthermore, it can preliminarily analyze the sensitivity of each oscillation mode to the safe operation of the unit and the power grid, making it closer to engineering practice than previous theoretical analysis and simulation modeling methods. The invention will be described in detail below with reference to the accompanying drawings.

[0049] Figure 1 This is a flowchart of a wind turbine oscillation testing method based on voltage excitation, as described in an embodiment of the present invention. Figure 1 As shown, the voltage-excited wind turbine oscillation test method includes:

[0050] S101: Controls the power converter in the grid-connected test device to generate a voltage excitation signal to the wind turbine.

[0051] The amplitude of the small-signal voltage excitation is usually set to 2% to 5% of the fundamental voltage, the frequency setting range is 0.1Hz to 10Hz, the frequency interval is set to 0.1Hz, and the disturbance time of a single small-signal voltage source is not less than 10s.

[0052] S102: Collect the generator speed vector within the disturbance frequency range of the wind turbine.

[0053] The generator speed vector, voltage signal, and current signal of the wind turbine are all collected by the wind turbine voltage / current testing equipment arranged inside the wind turbine tower.

[0054] S103: Determine the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency.

[0055] In practice, the rotational speed deviation index at each disturbance frequency can be determined using the following formula:

[0056]

[0057] Among them, w′ mi Let w be the generator speed vector at disturbance frequency i. mi This is the generator speed vector at disturbance frequency i after median filtering. `Midfilter()` performs median filtering on the data. m1i For w mi The initial value of the vector, w mendi For w mi The vector final value, n1 is the minimum frequency, n2 is the maximum frequency, k is the perturbation frequency interval, and Index speedi This is the speed deviation index at disturbance frequency i.

[0058] Figure 2 This is a flowchart of S103 in an embodiment of the present invention. For example... Figure 2 As shown, S103 includes:

[0059] S201: Collects the voltage and current signals of the wind turbine generator and determines the impedance amplitude and impedance phase angle based on the voltage and current signals.

[0060] In practice, the impedance amplitude and impedance phase angle within the test frequency range can be calculated using the discrete Fourier transform method.

[0061] S202: Determine the smoothness of the positive sequence impedance at the wind turbine terminals based on the impedance amplitude and impedance phase angle.

[0062] S203: When the smoothness of the positive sequence impedance at the wind turbine terminal meets the preset smoothness condition, the speed deviation index at each disturbance frequency is determined based on the generator speed vector at each disturbance frequency.

[0063] The smoothness of the positive sequence impedance at the wind turbine terminals is used to determine the validity of the test. If the test is deemed invalid, the amplitude of the small signal voltage excitation is adjusted as appropriate, and the above steps are repeated. If the test is deemed valid, S103 is executed.

[0064] S104: Determine the target oscillation mode frequency of the wind turbine based on the comparison results of the speed deviation index at each disturbance frequency with the preset threshold and the comparison results of the speed deviation index at the corresponding previous disturbance frequency with the preset threshold.

[0065] In practical implementation, a speed deviation index judgment threshold g is set to judge the degree of speed fluctuation. If Index speedi >g and Index speed(i-1) If ≤g, then the identification frequency i is the low-frequency oscillation mode frequency of the wind turbine (the target oscillation mode frequency of the wind turbine).

[0066] After executing S104, the following steps are also included: determining the target oscillation mode frequency of the wind turbine corresponding to the maximum value of the speed deviation index under the target oscillation mode frequency of each wind turbine as the shaft oscillation mode frequency.

[0067] Figure 1 The execution entity of the voltage-excited wind turbine oscillation test method shown can be a DSP (Digital Signal Processing) control unit. Figure 1 As shown in the flowchart, the voltage-excited wind turbine oscillation test method of this embodiment first controls the power converter in the grid-connected test device to generate a voltage excitation signal to the wind turbine, and then determines the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency to determine the target oscillation mode frequency of the wind turbine. This method can quickly and effectively identify the oscillation mode of the wind turbine, greatly improve test efficiency, and reduce test costs.

[0068] Based on the same inventive concept, this invention also provides a voltage-excited wind turbine oscillation testing device. Since the principle of this device in solving the problem is similar to that of the voltage-excited wind turbine oscillation testing method, the implementation of this device can refer to the implementation of the method, and the repeated parts will not be described again.

[0069] Figure 3 This is a structural block diagram of a wind turbine oscillation testing device based on voltage excitation, as described in an embodiment of the present invention. Figure 3 As shown, the voltage-excited wind turbine oscillation testing device includes:

[0070] The power converter control module is used to control the power converter in the grid-connected test device to generate voltage excitation signals to the wind turbine.

[0071] The generator speed vector module is used to collect the generator speed vector within the disturbance frequency range of the wind turbine.

[0072] The speed deviation index module is used to determine the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency.

[0073] The target oscillation mode frequency module is used to determine the target oscillation mode frequency of the wind turbine based on the comparison results of the speed deviation index at each disturbance frequency with the preset threshold and the comparison results of the speed deviation index at the corresponding previous disturbance frequency with the preset threshold.

[0074] In one embodiment, it further includes:

[0075] The shaft oscillation mode frequency module is used to determine the target oscillation mode frequency of the wind turbine corresponding to the maximum value of the speed deviation index under the target oscillation mode frequency of each wind turbine.

[0076] In one embodiment, the speed deviation index module includes:

[0077] The impedance value determination unit is used to collect the voltage and current signals of the wind turbine and determine the impedance amplitude and impedance phase angle based on the voltage and current signals.

[0078] Positive sequence impedance smoothness unit, used to determine the positive sequence impedance smoothness of the wind turbine terminals based on impedance amplitude and impedance phase angle;

[0079] The speed deviation index unit is used to determine the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency when the smoothness of the positive sequence impedance at the wind turbine terminal meets the preset smoothness conditions.

[0080] In summary, the voltage-excited wind turbine oscillation testing device of this invention first controls the power converter in the grid-connected testing device to generate a voltage excitation signal to the wind turbine, and then determines the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency to determine the target oscillation mode frequency of the wind turbine. This can quickly and effectively identify the oscillation mode of the wind turbine, greatly improve testing efficiency, and reduce testing costs.

[0081] Figure 4 This is a schematic block diagram illustrating the system configuration of the electronic device 9600 according to an embodiment of this application. Figure 4 As shown, the electronic device 9600 may include a central processing unit 9100 and a memory 9140; the memory 9140 is coupled to the central processing unit 9100. It is worth noting that... Figure 4 This is an example; other types of structures can also be used to supplement or replace this structure to achieve telecommunications functions or other functions.

[0082] In one embodiment, the voltage-excited wind turbine oscillation testing method can be integrated into the central processing unit 9100. The central processing unit 9100 can be configured to perform the following control:

[0083] The power converter in the grid-connected test device is controlled to generate a voltage excitation signal to the wind turbine.

[0084] Collect the generator speed vector within the disturbance frequency range of the wind turbine;

[0085] The speed deviation index at each disturbance frequency is determined based on the generator speed vector at each disturbance frequency.

[0086] The target oscillation mode frequency of the wind turbine is determined by comparing the speed deviation index at each disturbance frequency with the preset threshold and the speed deviation index at the corresponding previous disturbance frequency with the preset threshold.

[0087] As can be seen from the above description, the voltage-excited wind turbine oscillation test method of the present invention first controls the power converter in the grid-connected test device to generate a voltage excitation signal to the wind turbine, and then determines the speed deviation index at each disturbance frequency according to the generator speed vector at each disturbance frequency to determine the target oscillation mode frequency of the wind turbine. This method can quickly and effectively identify the oscillation mode of the wind turbine, greatly improve test efficiency, and reduce test costs.

[0088] In another embodiment, the voltage-excited wind turbine oscillation test device can be configured separately from the central processing unit 9100. For example, the voltage-excited wind turbine oscillation test device can be configured as a chip connected to the central processing unit 9100, and the function of the voltage-excited wind turbine oscillation test method can be realized through the control of the central processing unit.

[0089] like Figure 4 As shown, the electronic device 9600 may further include: a communication module 9110, an input unit 9120, an audio processor 9130, a display 9160, and a power supply 9170. It is worth noting that the electronic device 9600 does not necessarily need to include these components. Figure 4 All components shown; in addition, the electronic device 9600 may also include Figure 4 For components not shown, please refer to existing technologies.

[0090] like Figure 4 As shown, the central processing unit 9100, sometimes also referred to as a controller or operating control, may include a microprocessor or other processor device and / or logic device, which receives inputs and controls the operation of various components of the electronic device 9600.

[0091] The memory 9140 may be, for example, one or more of a cache, flash memory, hard drive, removable media, volatile memory, non-volatile memory, or other suitable devices. It may store the aforementioned failure-related information, and also store a program for executing that information. The central processing unit 9100 may execute the program stored in the memory 9140 to perform information storage or processing, etc.

[0092] Input unit 9120 provides input to central processing unit 9100. Input unit 9120 may be, for example, a keypad or touch input device. Power supply 9170 provides power to electronic device 9600. Display 9160 displays images and text. Display may be, for example, an LCD display, but is not limited thereto.

[0093] The memory 9140 can be a solid-state memory, such as a read-only memory (ROM), random access memory (RAM), a SIM card, etc. It can also be a memory that retains information even when power is off, can be selectively erased, and contains more data; examples of this type of memory are sometimes referred to as EPROMs. The memory 9140 can also be some other type of device. The memory 9140 includes a buffer memory 9141 (sometimes referred to as a buffer). The memory 9140 may include an application / function storage unit 9142 for storing application programs and function programs or processes for executing the operation of the electronic device 9600 via the central processing unit 9100.

[0094] The memory 9140 may also include a data storage unit 9143 for storing data, such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. The driver storage unit 9144 of the memory 9140 may include various drivers for the electronic device's communication functions and / or for performing other functions of the electronic device (such as messaging applications, address book applications, etc.).

[0095] The communication module 9110 is a transmitter / receiver 9110 that transmits and receives signals via the antenna 9111. The communication module (transmitter / receiver) 9110 is coupled to the central processing unit 9100 to provide input signals and receive output signals, which can be the same as in a conventional mobile communication terminal.

[0096] Based on different communication technologies, multiple communication modules 9110 can be configured in the same electronic device, such as cellular network modules, Bluetooth modules, and / or wireless LAN modules. The communication module (transmitter / receiver) 9110 is also coupled to a speaker 9131 and a microphone 9132 via an audio processor 9130 to provide audio output via the speaker 9131 and receive audio input from the microphone 9132, thereby realizing typical telecommunications functions. The audio processor 9130 may include any suitable buffer, decoder, amplifier, etc. Additionally, the audio processor 9130 is coupled to a central processing unit 9100, enabling on-device recording via the microphone 9132 and on-device playback of stored sound via the speaker 9131.

[0097] This invention also provides a computer-readable storage medium capable of implementing all steps of the voltage-excited wind turbine oscillation testing method described in the above embodiments, where the execution subject is a server or client. The computer-readable storage medium stores a computer program that, when executed by a processor, implements all steps of the voltage-excited wind turbine oscillation testing method described in the above embodiments. For example, when the processor executes the computer program, it implements the following steps:

[0098] The power converter in the grid-connected test device is controlled to generate a voltage excitation signal to the wind turbine.

[0099] Collect the generator speed vector within the disturbance frequency range of the wind turbine;

[0100] The speed deviation index at each disturbance frequency is determined based on the generator speed vector at each disturbance frequency.

[0101] The target oscillation mode frequency of the wind turbine is determined by comparing the speed deviation index at each disturbance frequency with the preset threshold and the speed deviation index at the corresponding previous disturbance frequency with the preset threshold.

[0102] In summary, the computer-readable storage medium of this embodiment first controls the power converter in the grid-connected test device to generate a voltage excitation signal to the wind turbine, and then determines the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency to determine the target oscillation mode frequency of the wind turbine. This can quickly and effectively identify the oscillation mode of the wind turbine, greatly improve test efficiency, and reduce test costs.

[0103] This invention also provides a computer program product capable of implementing all steps of the voltage-excited wind turbine oscillation testing method described in the above embodiments, where the execution subject is a server or client. The computer program product includes a computer program / instruction that, when executed by a processor, implements all steps of the voltage-excited wind turbine oscillation testing method described in the above embodiments. For example, when the processor executes the computer program, it implements the following steps:

[0104] The power converter in the grid-connected test device is controlled to generate a voltage excitation signal to the wind turbine.

[0105] Collect the generator speed vector within the disturbance frequency range of the wind turbine;

[0106] The speed deviation index at each disturbance frequency is determined based on the generator speed vector at each disturbance frequency.

[0107] The target oscillation mode frequency of the wind turbine is determined by comparing the speed deviation index at each disturbance frequency with the preset threshold and the speed deviation index at the corresponding previous disturbance frequency with the preset threshold.

[0108] In summary, the computer program product of this invention first controls the power converter in the grid-connected test device to generate a voltage excitation signal to the wind turbine, and then determines the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency to determine the target oscillation mode frequency of the wind turbine. This can quickly and effectively identify the oscillation mode of the wind turbine, greatly improve test efficiency, and reduce test costs.

[0109] Based on the same inventive concept, this invention also provides a voltage-excited wind turbine oscillation testing system. Since the principle of this system in solving the problem is similar to that of the voltage-excited wind turbine oscillation testing method, the implementation of this system can refer to the implementation of the method, and the repeated parts will not be described again.

[0110] Figure 5 This is a schematic diagram of a wind turbine oscillation testing system based on voltage excitation, as described in an embodiment of the present invention. Figure 5 As shown, the voltage-excited wind turbine oscillation test system includes:

[0111] Power grid;

[0112] Wind turbine units;

[0113] A grid-connected testing device, connected to both the power grid and the wind turbine, is used to generate voltage excitation signals to the wind turbine; and

[0114] The voltage-excited wind turbine oscillation test device described above is applied to the DSP control unit and connected to the grid-connected test device.

[0115] like Figure 5 As shown, the grid-connected test device includes a power converter, a series transformer, a parallel transformer, and a circuit breaker. The input of the grid-connected test device is connected to the power grid, and the output is connected to the wind turbine generator set, which serves as the device under test. The power converter has a bidirectional flow converter topology and is used to provide the voltage waveform required for the test to the series and parallel transformers. The series transformer is a three-winding transformer, connected to the circuit breaker S2 on the secondary side, used to couple the test voltage waveform output by the power converter to the primary side of the transformer through a complex winding, forming a small-signal voltage excitation signal for low-frequency oscillation mode testing. The parallel transformer is also a three-winding transformer, connected to the circuit breaker S3 on the secondary side, which can couple the test frequency output by the power converter to the primary side of the transformer through a complex winding. The circuit breaker is used to protect the device under test and change the equipment's operating mode. The DSP control unit is used to control the circuit breaker to output voltage, frequency, and phase that meet the test requirements, and to acquire the generator speed vector, voltage signal, and current signal collected by the wind turbine generator voltage / current test equipment arranged inside the wind turbine tower.

[0116] The specific process of the voltage-excited wind turbine oscillation testing system according to an embodiment of the present invention is as follows:

[0117] 1. Shut down the doubly fed wind turbine to be tested and disconnect the connecting cable between the wind turbine and the unit's box transformer.

[0118] 2. Connect the grid-connected testing device in series between the doubly fed wind turbine under test and the turbine's box-type transformer, and arrange the wind turbine voltage / current testing equipment inside the wind turbine tower.

[0119] 3. Close the circuit breaker S1 of the grid connection test device to put the grid connection test device in bypass mode and restart the wind turbine to generate electricity.

[0120] 4. The amplitude of the small signal voltage excitation is usually set to 2% to 5% of the fundamental voltage, the frequency setting range is 0.1Hz to 10Hz, the frequency interval is set to 0.1Hz, and the disturbance time of a single small signal voltage source is not less than 10s.

[0121] 5. Wait for the wind turbine to reach a stable operating condition, then simultaneously disconnect circuit breaker S1 and close circuit breaker S2 to put the grid connection test device into the preparation state.

[0122] 6. Close circuit breaker S4 to put the equipment into test mode. Use the DSP control unit to control the power converter to generate a small signal voltage excitation signal, and apply the small signal voltage excitation to the wind turbine through the complex winding of the series transformer. Use the wind turbine voltage / current testing equipment to test the generator speed, terminal voltage, and terminal current response of the wind turbine.

[0123] 7. Collect the voltage and current signals of the wind turbine generator, and determine the impedance amplitude and impedance phase angle based on the voltage and current signals.

[0124] 8. Determine the smoothness of the positive sequence impedance at the wind turbine terminals based on the impedance amplitude and impedance phase angle. The smoothness of the positive sequence impedance at the wind turbine terminals is used to determine the validity of the test. If the test is determined to be invalid, adjust the small-signal voltage excitation amplitude as appropriate and repeat steps 4-7; if the test is determined to be valid, proceed to the next step.

[0125] 9. Determine the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency.

[0126] 10. Determine the target oscillation mode frequency of the wind turbine based on the comparison results of the speed deviation index at each disturbance frequency with the preset threshold and the comparison results of the speed deviation index at the corresponding previous disturbance frequency with the preset threshold.

[0127] 11. The target oscillation mode frequency of the wind turbine corresponding to the maximum value of the speed deviation index under the target oscillation mode frequency of each wind turbine is the shaft oscillation mode frequency.

[0128] Figure 6 This is a schematic diagram of the positive sequence impedance amplitude of the wind turbine generator terminal under test in an embodiment of the present invention. Figure 7 This is a schematic diagram of the positive sequence impedance phase angle at the turbine terminal of the wind turbine under test in an embodiment of the present invention. For example... Figures 6-7 As shown, using the above steps, a low-frequency oscillation frequency test was conducted on a 5.0MW doubly-fed wind turbine generator from a certain wind turbine manufacturer. Under rated power conditions, a small-signal voltage excitation of 2% fundamental voltage, a frequency setting range of 0.1Hz to 10Hz, a frequency interval of 0.1Hz, and a single disturbance time of 12s was injected into the wind turbine generator using a grid-connected testing device, resulting in... Figure 6 and Figure 7 .according to Figure 6 and Figure 7 This test can be considered reliable and effective.

[0129] Figure 8 This is a schematic diagram of the generator speed response waveform in an embodiment of the present invention. Figure 9 This is a schematic diagram of the speed deviation index waveform in an embodiment of the present invention. For example... Figures 8-9As shown, the threshold for judging the speed deviation index is set to 0.1. Based on the relationship between the speed deviation index and the threshold, it can be seen that the generator speed and unit output of the wind turbine fluctuate to varying degrees when the disturbance voltage test is conducted in the frequency bands of 0.5Hz, 1.1Hz, 1.6Hz, and 2.7Hz. These frequencies are considered to be the low-frequency oscillation modes (target oscillation modes) of the blades or tower in the windward direction. Among them, the generator speed deviation index corresponding to the disturbance voltage test in the 1.6Hz frequency band is the maximum value, and this frequency is identified as the shaft oscillation mode frequency of the doubly-fed induction generator under test.

[0130] Table 1

[0131]

[0132]

[0133] Table 1 is a schematic table of theoretical values ​​for the low-frequency oscillation modes of the wind turbine under test. Table 1 (1.614, 0.410, 1.084, and 2.678 in Table 1) and... Figure 9 The comparison results show that the present invention can effectively identify and obtain the shaft oscillation mode and the main windward low-frequency oscillation mode of the wind turbine.

[0134] In summary, the voltage-excited wind turbine oscillation testing method provided by the embodiments of the present invention has the following beneficial effects:

[0135] (1) It can quickly measure and obtain the oscillation frequency of the wind turbine shaft system and other low-frequency oscillation frequencies that affect the grid connection characteristics of the unit without opening the unit equipment or affecting the normal operation of the unit. It can also preliminarily analyze the sensitivity of each oscillation mode to the safe operation of the unit and the stability of the power grid. The test results can effectively identify the main low-frequency oscillation modes related to the grid connection of the doubly fed wind turbine. Compared with theoretical analysis, it can more accurately reflect the actual oscillation characteristics of the project, while avoiding the limitations of traditional testing.

[0136] (2) The capacity design of the power converter of the grid-connected test device used in this invention only needs to meet the capacity required by the small signal voltage source (within 1% of the rated power). Therefore, the capacity design of the power converter can be much smaller than the rated capacity of the device under test, which brings a series of advantages such as low test cost, small size, light weight and low heat generation. The grid-connected test device can be integrated into a container to form a mobile test device, which greatly improves the test efficiency and reduces the test cost.

[0137] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are 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 within the scope of protection of the present invention.

[0138] Those skilled in the art will also understand that the various illustrative logical blocks, units, and steps listed in the embodiments of the present invention can be implemented by electronic hardware, computer software, or a combination of both. To clearly demonstrate the interchangeability of hardware and software, the functions of the various illustrative components, units, and steps described above have been generally described. Whether such functionality is implemented through hardware or software depends on the specific application and the overall system design requirements. Those skilled in the art can implement the described functions using various methods for each specific application, but such implementation should not be construed as exceeding the scope of protection of the embodiments of the present invention.

[0139] The various illustrative logic blocks, units, or devices described in the embodiments of this invention can be implemented or operate the described functions using a general-purpose processor, digital signal processor, application-specific integrated circuit (ASIC), field-programmable gate array or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The general-purpose processor can be a microprocessor; alternatively, it can be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented using a combination of computing devices, such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors combined with a digital signal processor core, or any other similar configuration.

[0140] The steps of the methods or algorithms described in the embodiments of this invention can be directly embedded in hardware, a software module executed by a processor, or a combination of both. The software module can be stored in RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium in the art. Exemplarily, the storage medium can be connected to the processor so that the processor can read information from and write information to the storage medium. Optionally, the storage medium can also be integrated into the processor. The processor and storage medium can be housed in an ASIC, which can be housed in a user terminal. Optionally, the processor and storage medium can also be housed in different components of the user terminal.

[0141] In one or more exemplary designs, the functions described in the embodiments of the present invention can be implemented in hardware, software, firmware, or any combination of these three. If implemented in software, these functions can be stored on a computer-readable medium or transmitted on a computer-readable medium in the form of one or more instructions or code. Computer-readable media include computer storage media and communication media that facilitate the transfer of computer programs from one place to another. Storage media can be any available media that can be accessed by a general-purpose or special-purpose computer. For example, such computer-readable media can include, but is not limited to, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store program code in the form of instructions or data structures and other forms that can be read by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Furthermore, any connection can be suitably defined as a computer-readable medium, for example, if the software is transmitted from a website, server or other remote resource via a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wirelessly, such as infrared, wireless and microwave, it is also included in the defined computer-readable medium. The disks and discs mentioned include compressed disks, laser discs, optical discs, DVDs, floppy disks, and Blu-ray discs. Disks typically copy data magnetically, while disks typically copy data optically using lasers. Combinations of the above can also be contained in computer-readable media.

Claims

1. A method for testing the oscillation of a wind turbine based on voltage excitation, characterized in that, include: The power converter in the grid-connected test device is controlled to generate a voltage excitation signal to the wind turbine. Collect the generator speed vector within the disturbance frequency range of the wind turbine; The speed deviation index at each disturbance frequency is determined based on the generator speed vector at each disturbance frequency. The target oscillation mode frequency of the wind turbine is determined based on the comparison results of the speed deviation index at each disturbance frequency with the preset threshold and the comparison results of the speed deviation index at the corresponding previous disturbance frequency with the preset threshold. The speed deviation index at each disturbance frequency is determined based on the generator speed vector at each disturbance frequency, including: The voltage and current signals of the wind turbine are collected, and the impedance amplitude and impedance phase angle are determined based on the voltage and current signals. The smoothness of the positive sequence impedance at the wind turbine terminals is determined based on the impedance amplitude and the impedance phase angle. When the smoothness of the positive sequence impedance at the wind turbine terminal meets the preset smoothing condition, the speed deviation index at each disturbance frequency is determined based on the generator speed vector at each disturbance frequency.

2. The wind turbine oscillation test method based on voltage excitation according to claim 1, characterized in that, Also includes: The target oscillation mode frequency of the wind turbine corresponding to the maximum value of the speed deviation index under the target oscillation mode frequency of each wind turbine is determined as the shaft oscillation mode frequency.

3. A wind turbine oscillation testing device based on voltage excitation, characterized in that, include: The power converter control module is used to control the power converter in the grid-connected test device to generate voltage excitation signals to the wind turbine. The generator speed vector module is used to collect the generator speed vector within the disturbance frequency range of the wind turbine. The speed deviation index module is used to determine the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency. The target oscillation mode frequency module is used to determine the target oscillation mode frequency of the wind turbine based on the comparison results of the speed deviation index at each disturbance frequency with the preset threshold and the comparison results of the speed deviation index at the corresponding previous disturbance frequency with the preset threshold. The speed deviation index module includes: The impedance value determination unit is used to collect the voltage and current signals of the wind turbine generator and determine the impedance amplitude and impedance phase angle based on the voltage and current signals. A positive sequence impedance smoothness unit is used to determine the positive sequence impedance smoothness of the wind turbine terminal based on the impedance amplitude and the impedance phase angle value. The speed deviation index unit is used to determine the speed deviation index at each disturbance frequency based on the generator speed vector at each disturbance frequency when the smoothness of the positive sequence impedance at the wind turbine terminal meets the preset smoothing conditions.

4. The wind turbine oscillation testing device based on voltage excitation according to claim 3, characterized in that, Also includes: The shaft oscillation mode frequency module is used to determine the target oscillation mode frequency of the wind turbine corresponding to the maximum value of the speed deviation index under the target oscillation mode frequency of each wind turbine.

5. 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, it implements the steps of the voltage-excited wind turbine oscillation test method according to any one of claims 1 to 3.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the voltage-excited wind turbine oscillation test method as described in claim 1 or 2.

7. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the voltage-excited wind turbine oscillation test method as described in claim 1 or 2.

8. A wind turbine oscillation testing system based on voltage excitation, characterized in that, include: Power grid; Wind turbine units; A grid-connected test device that is connected to the power grid and the wind turbine respectively is used to generate a voltage excitation signal to the wind turbine. as well as The voltage-excited wind turbine oscillation test device according to claim 3 or 4 is connected to the grid-connected test device.

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