Inertia compensation method and system for full-power ground test platform of wind turbine generator

Abstract

The invention provides an inertia compensation method and system for a full-power ground test platform of a wind turbine generator, and the method comprises the steps: obtaining the ground test data of a wind turbine without inertia simulation, extracting the main harmonic frequency of the rotating speed, and setting the frequency as the cut-off frequency c of an observer; calculating a feedback gain coefficient KP and an integral gain coefficient Ki of the observer according to the cut-off frequency c; and generating an acceleration estimation value by using the observer with the gain coefficient according to the actual rotating speed of the generator, and further generating an inertia compensation torque. The main harmonic frequency of the rotating speed is measured, the cut-off frequency of the observer is determined, parameter setting is further achieved, and the operation performance of the observer is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wind power generation, and relates to an inertia compensation method and system for a full-power ground test platform of a wind turbine generator set. 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 development trend of the wind power industry towards large-scale and deep-sea operations, the capacity of individual wind turbines continues to increase, placing higher demands on the reliability, dynamic response capabilities, and grid-connected performance of the entire system. Limited by factors such as complex offshore testing conditions, high construction costs, and long testing cycles, an increasing number of wind turbine manufacturers and research institutions are inclined to build onshore wind turbine ground transmission chain test platforms to simulate the actual operating environment of wind turbines and conduct system-level full-power testing. This type of test platform can provide controllable, reproducible, and highly realistic testing conditions in a terrestrial environment, becoming a key technical means to accelerate wind power technology research and development and reduce the risks and costs of offshore testing.

[0004] A full-power ground test platform for a wind turbine typically includes a traction motor system (used to simulate the wind rotor), the generator system under test, a power conversion and control system, and grid-connection equipment. The platform connects the traction motor to the generator via a mechanical coupling device, and performs load control and energy feedback on the electrical side, enabling dynamic simulation of the generator's operating state under different wind conditions.

[0005] As a core component of the ground test system, the traction motor plays a crucial role in simulating the dynamic characteristics of a real wind turbine rotor. However, due to the lack of an actual impeller in the ground test system, the traction motor's equivalent inertia is much lower than that of a real wind turbine rotor. This makes accurately simulating the rotor's inertia a technical bottleneck restricting the effectiveness of the ground test system.

[0006] At present, inertia algorithm compensation is the mainstream inertia simulation method, which introduces acceleration signals through the differential link to further calculate the equivalent torque of the wind wheel inertia. However, this link will amplify high-frequency harmonics, which can easily cause resonance in actual operation and seriously affect the stability of the system. In order to solve this problem, the Luenberger observer is introduced in the existing technology to replace the differential link to filter out high-frequency harmonics and achieve effective measurement of the acceleration signal. The observer adjusts the compensation amount in time according to the generator speed through the feedback corrector, so that the observed speed can track the actual speed, thereby avoiding the instability problem to a certain extent. Among them, the feedback gain coefficient K P The choice of is a key issue. Feedback gain coefficient K PIf the value is too large, although it can improve the speed of the observer to track the speed, it will introduce high-order harmonics, affecting the stability of the system operation, and the feedback gain coefficient K P If the value is too small, the observer's tracking speed will be slow, resulting in the observed speed not being able to track the actual speed in a timely manner, and inability to achieve accurate inertia simulation. In addition, the choice of the Luenberger observer cutoff frequency will also affect the effectiveness of the inertia compensation system.

[0007] In summary, the parameter setting of the Luenberger observer has a crucial impact on the accuracy of inertia simulation and the stability of the system. However, the current lack of effective parameter tuning methods makes it difficult to effectively guarantee the accuracy of inertia simulation and the stability of the system. Summary of the Invention

[0008] To solve the above problems, the present invention proposes an inertia compensation method and system for a full-power ground test platform for wind turbines. The present invention determines the cutoff frequency of the Luenberger observer by measuring the main harmonic frequencies of the rotational speed, further realizes its parameter setting, and effectively improves the observer's operating performance.

[0009] According to some embodiments, the present invention adopts the following technical solutions: A method for compensating inertia of a full-power ground test platform for a wind turbine generator system comprises the following steps: Obtain the ground test data of the wind turbine with no inertia simulation, extract the main harmonic frequency of the speed, and set the frequency as the cutoff frequency of the observer ; According to the cutoff frequency , calculate the feedback gain coefficient of the observer K P and the integral gain coefficient K i ; The observer with the above-mentioned gain coefficient is used to generate an acceleration estimation value according to the actual generator speed, and then generate the inertia compensation torque.

[0010] As an alternative embodiment, according to the cut-off frequency , calculate the feedback gain coefficient of the observer K P The process includes: .

[0011] As an alternative embodiment, according to the cut-off frequency , calculate the integral gain coefficient of the observer K i The process includes: .

[0012] As an optional implementation, the observer is a Romberg observer.

[0013] As an optional embodiment, the process of generating an acceleration estimate based on the actual generator speed using an observer having the above-mentioned gain coefficient includes: embedding the observer having the above-mentioned gain coefficient into an inertia simulation control system, with the actual generator speed as input and the acceleration estimate as output.

[0014] As an optional implementation, it also includes using the product of the acceleration signal output by the observer and the inertia difference to correct the test unit torque so that the equivalent inertia of the traction motor matches the real fan impeller.

[0015] As a further implementation method, the process of correcting the torque of the test unit includes: introducing an acceleration signal through an observer, multiplying the inertia compensation difference to obtain a compensation torque, and superimposing it with the aerodynamic torque of the fan to generate an inverter torque control signal to drive the motor to simulate the actual impeller output torque.

[0016] An inertia compensation system for a full-power ground test platform of a wind turbine generator system, comprising: The cutoff frequency setting module is configured to obtain the wind turbine ground test data without inertia simulation, extract the main harmonic frequency of the speed, and set the frequency as the cutoff frequency of the observer. ; The gain coefficient calculation module is configured to calculate the gain coefficient according to the cutoff frequency. , calculate the feedback gain coefficient of the observer K P and the integral gain coefficient K i ; The inertia compensation torque generation module is configured to generate an acceleration estimation value according to the actual generator speed using an observer with the above-mentioned gain coefficient, and then generate the inertia compensation torque.

[0017] A terminal device includes a processor and a computer-readable storage medium, wherein the processor is used to implement various instructions; the computer-readable storage medium is used to store multiple instructions, and the instructions are suitable for being loaded by the processor and executing the steps in the described method.

[0018] A wind power control system includes a processor and a computer-readable storage medium, wherein the processor is used to implement various instructions; the computer-readable storage medium is used to store multiple instructions, wherein the instructions are suitable for being loaded by the processor and executing the steps in the described method.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The cutoff frequency ƒ extracted by the preliminary test of the present invention cDynamically adjust observer parameters to avoid the blindness of manual parameter adjustment.

[0020] The present invention uses the gain coefficient K i The mathematical derivation of the method limits the phase delay, takes into account both tracking speed and harmonic suppression, and can be calculated only based on the cutoff frequency, making the overall process simple.

[0021] The present invention optimizes the low-pass characteristics of the observer, can enhance the high-frequency noise filtering capability, strengthen the system's anti-interference performance, and improve the system's stability.

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 This is a block diagram of inertia compensation control based on differential link in the prior art; Figure 2 is an inertia compensation control scheme based on Luenberger observer in one embodiment; Figure 3 is a corresponding Bode diagram in one embodiment; Figure 4 This is a schematic diagram of the inertia compensation control effect under optimal parameters in an embodiment; Figure 5 This is a schematic diagram of the inertia compensation control effect when the optimal parameters are increased in one embodiment; Figure 6 It is a schematic diagram of the inertia compensation control effect when the optimal parameters are reduced in an embodiment. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] Example 1 A method for compensating inertia of a full-power ground test platform for a wind turbine generator system comprises the following steps: Obtain ground test data of a wind turbine with no inertia simulation, extract the main harmonic frequency of the speed, and set the frequency as the cutoff frequency of the observer (i.e., Luenberger observer) ; According to the cutoff frequency , calculate the feedback gain coefficient of the observer K P and the integral gain coefficient K i ; The observer with the above-mentioned gain coefficient is used to generate an acceleration estimation value according to the actual generator speed, and then generate the inertia compensation torque.

[0029] According to the cutoff frequency , calculate the feedback gain coefficient of the observer K P The process includes: .

[0030] According to the cutoff frequency , calculate the integral gain coefficient of the observer K i The process includes: .

[0031] The process of generating an acceleration estimation value according to the actual generator speed using the observer with the above-mentioned gain coefficient includes: embedding the observer with the above-mentioned gain coefficient into the inertia simulation control system, inputting the actual generator speed and outputting the acceleration estimation value.

[0032] It also includes using the product of the acceleration signal output by the observer and the inertia difference to correct the drag motor torque so that its equivalent inertia matches the real fan impeller.

[0033] Among them, the process of correcting the torque of the test unit includes: introducing the acceleration signal through the observer, multiplying the inertia compensation difference to obtain the compensation torque, and superimposing it with the aerodynamic torque of the fan to generate the inverter torque control signal to drive the motor to simulate the actual impeller output torque.

[0034] A detailed description and related derivations are given below.

[0035] This embodiment selects the offshore wind turbine ground test research scenario and permanent magnet direct-drive wind turbine as the research target. According to the motion equation of the actual operation of the offshore wind turbine and the motion equation of the offshore wind turbine ground test, it can be obtained: (1) (2) Where: T r is the actual mechanical torque of the fan, T g is the electromagnetic torque of the fan, T s To test the mechanical torque of the fan, ω g is the actual fan speed, ω s is the speed of the test fan.

[0036] In order to simulate the actual dynamic performance of the fan, the speeds of the two are made the same, that is, ω g equal ω s , subtracting the two equations, we get: (3) The left side of the equal sign in the above formula represents the torque reference value that the ground test motor needs to output: the first part on the right side of the equal sign represents the aerodynamic torque actually output by the wind turbine, and the second part represents the virtual compensation torque for dynamic torque compensation using the transmission shaft acceleration signal.

[0037] The inertia compensation control scheme based on the differential link and the Luenberger observer is as follows: Figure 1 and Figure 2 As shown, in this embodiment, the differential link is replaced by the Luenberger observer to reduce the impact of high-order harmonics caused by the differential link on the system and improve the stability and effectiveness of inertia compensation control.

[0038] The control system introduces the acceleration signal through the observer, further multiplies the inertia compensation difference to obtain the compensation torque, and finally superimposes it with the fan aerodynamic torque to generate the inverter torque control signal to drive the motor to simulate the actual impeller output torque.

[0039] Figure 2 The forward channel part of the observer is the torque compensation loop. The feedback corrector adjusts the compensation amount in time according to the generator speed so that the observed speed can track the actual speed, ensuring that the system model obtains an accurate acceleration estimate in the presence of noise and other interference.

[0040] To ensure that the Luenberger observer can accurately track the acceleration of the unit, a larger feedback gain coefficient can be selected. K P However, if the feedback gain coefficient of the observer is too large, high-order harmonics will be introduced, which will make the use of the Luenberger observer meaningless. At the same time, if the feedback gain coefficient of the observer is too small, it will make it difficult for the observed speed to track the actual speed, and the inertia simulation of the fan will also be impossible.

[0041] The transfer function of the Luenberger observer is shown in formula (4), and the corresponding Bode diagram is as follows Figure 4 For the speed signal, the observer is equivalent to a low-pass filter, filtering the cutoff frequency ƒ c After simplifying the calculation, the cutoff frequency of the observer is ƒ c= K p (rad / s), further confirm K p After that, we can calculate K i To achieve the minimum phase error of 36.87 degrees, the minimum delay time using the Luenberger observer is (36.87 / 360) / .

[0042] The optimal Luenberger observer parameters are finally determined as: Feedback gain coefficient ; Integral gain coefficient .

[0043] (4) In order to achieve dynamic simulation of the fan, the ground test of the fan in this embodiment needs to simulate the normal fluctuation of the fan speed. In other words, as long as the cutoff frequency of the observer is greater than the main fluctuation frequency of the fan speed, the accuracy of the inertia simulation can be guaranteed. At the same time, the system inertia will not affect the frequency of the speed harmonics, so the fan ground test without inertia simulation can be carried out to determine the cutoff frequency. , and further tune the Luenberger observer parameters according to the optimal parameters.

[0044] In order to verify the feasibility and correctness of the wind turbine simulation scheme using the Luenberger observer with optimal parameters, this example established a wind power simulation system model in the Matlab / Simulink environment and built an inertia simulation experimental platform for a 2MW permanent magnet direct-drive wind turbine. The total inertia of the wind turbine was set to 106 kg˙m 2The ratio of actual inertia to virtual inertia is set to 1:19. The wind turbine operates in the MPPT range, and the wind speed increases from 9m / s to 10m / s. The effectiveness and accuracy of the virtual inertia are verified by observing the tracking state of the wind turbine wind speed and the steady-state harmonics of the speed. ω1 is the actual speed of the wind turbine, and ω2 is the speed of the wind turbine for inertia simulation. Under the test conditions without inertia simulation, the harmonic frequency of the wind turbine speed is measured to be 29HZ. According to the optimal parameters of the proposed Luenberger observer, K P =182.2, K i =16600.7.

[0045] The experimental results of Luenberger using the optimal parameters are as follows Figure 4 As shown in the figure, ω1 is the actual operating speed of the fan, and ω2 is the fan speed for inertia simulation. By comparing the tracking state of the fan speed climb and the speed harmonics of the fan in steady state, it is found that the fan speed for inertia simulation is basically consistent with the actual fan speed.

[0046] To compare the effectiveness of the designed optimal parameters, such as Figure 5 As shown, increase K P 、 K i The simulation test was carried out with the value of . It can be found that due to the excessive accuracy of Luenberger, high-frequency harmonics were introduced. By observing the experimental results, it can be found that there is a large error between the fan speed simulated by inertia and the actual fan speed. The virtual inertia cannot effectively represent the fan speed state. Figure 6 As shown, reduce K P 、 K i It can be found that due to the slow tracking speed of Luenberger, the steady-state harmonic speed of the fan speed is insufficient. Although the error of the speed is not large overall, it can be found through observation of the experimental results that the too small K P 、 K i The value will cause the wind turbine harmonic amplitude to increase significantly, and it is also impossible to simulate the actual wind turbine speed state.

[0047] Example 2 An inertia compensation system for a full-power ground test platform of a wind turbine generator system, comprising: The cutoff frequency setting module is configured to obtain the wind turbine ground test data without inertia simulation, extract the main harmonic frequency of the speed, and set the frequency as the cutoff frequency of the observer. ; The gain coefficient calculation module is configured to calculate the gain coefficient according to the cutoff frequency. , calculate the feedback gain coefficient of the observer K P and the integral gain coefficient K i ; The inertia compensation torque generation module is configured to generate an acceleration estimation value according to the actual generator speed using an observer with the above-mentioned gain coefficient, and then generate the inertia compensation torque.

[0048] Example 3 A terminal device includes a processor and a computer-readable storage medium, wherein the processor is used to implement various instructions; the computer-readable storage medium is used to store multiple instructions, and the instructions are suitable for being loaded by the processor and executing the steps in the method described in Example 1.

[0049] Example 4 A wind power control system includes a processor and a computer-readable storage medium, wherein the processor is used to implement various instructions; the computer-readable storage medium is used to store multiple instructions, wherein the instructions are suitable for being loaded by the processor and executing the steps of the method described in embodiment 1.

[0050] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, 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 magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0051] 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 flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, 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 flowcharts and / or block diagrams. 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.

[0052] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work 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 The function specified in one or more boxes.

[0053] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0054] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

[0055] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A method for compensating inertia of a full-power ground test platform for a wind turbine generator system, characterized in that: The following steps are involved: Obtain the wind turbine ground test data without inertia simulation, extract the main harmonic frequency of the speed, and set the frequency as the cutoff frequency of the observer ; According to the cutoff frequency , calculate the feedback gain coefficient of the observer K P and the integral gain coefficient K i ; The observer with the above-mentioned gain coefficient is used to generate an acceleration estimation value according to the actual generator speed, and then generate the inertia compensation torque.

2. The inertia compensation method for a full-power ground test platform for a wind turbine generator set according to claim 1, characterized in that: According to the cutoff frequency , calculate the feedback gain coefficient of the observer K P The process includes: .

3. The inertia compensation method for a full-power ground test platform for a wind turbine generator set according to claim 1, characterized in that: According to the cutoff frequency , calculate the integral gain coefficient of the observer K i The process includes: .

4. The inertia compensation method for a full-power ground test platform for a wind turbine generator set according to claim 1, wherein: The observer is a Lumberg observer.

5. The inertia compensation method for a full-power ground test platform for a wind turbine generator set according to claim 1, characterized in that: The process of generating an acceleration estimation value according to the actual generator speed using the observer with the above-mentioned gain coefficient includes: embedding the observer with the above-mentioned gain coefficient into the inertia simulation control system, inputting the actual generator speed and outputting the acceleration estimation value.

6. The inertia compensation method for a full-power ground test platform for a wind turbine generator set according to any one of claims 1 to 5, characterized in that: It also includes using the product of the acceleration signal output by the observer and the inertia difference to correct the test unit torque so that the system equivalent inertia matches the real fan impeller.

7. The inertia compensation method for a full-power ground test platform for a wind turbine generator set according to claim 6, characterized in that: The process of correcting the test unit torque includes: introducing the acceleration signal through the observer, multiplying the inertia compensation difference to obtain the compensation torque, and superimposing it with the fan aerodynamic torque to generate the inverter torque control signal to drive the motor to simulate the actual impeller output torque.

8. An inertia compensation system for a full-power ground test platform for a wind turbine generator set, characterized by: include: The cutoff frequency setting module is configured to obtain the wind turbine ground test data without inertia simulation, extract the main harmonic frequency of the speed, and set the frequency as the cutoff frequency of the observer. ; The gain coefficient calculation module is configured to calculate the gain coefficient according to the cutoff frequency. , calculate the feedback gain coefficient of the observer K P and the integral gain coefficient K i ; The inertia compensation torque generation module is configured to generate an acceleration estimation value according to the actual generator speed using an observer with the above-mentioned gain coefficient, and then generate the inertia compensation torque.

9. A terminal device, characterized in that: The method comprises a processor and a computer-readable storage medium, wherein the processor is used to implement various instructions; and the computer-readable storage medium is used to store a plurality of instructions, wherein the instructions are suitable for being loaded by the processor and executing the steps in the method according to any one of claims 1 to 7.

10. A wind power control system, characterized in that: The system comprises a processor and a computer-readable storage medium, wherein the processor is used to implement each instruction; the computer-readable storage medium is used to store multiple instructions, wherein the instructions are suitable for being loaded by the processor and executing the steps of the method described in any one of claims 1 to 7, or comprising the system described in claim 8.

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