An inertia compensation method and system for a full-power ground test platform of a wind turbine generator

Abstract

This invention provides an inertia compensation method and system for a full-power ground test platform for wind turbines. It acquires ground test data of the wind turbine without inertia simulation, extracts the main harmonic frequencies of the rotational speed, and sets these frequencies as the cutoff frequency ƒ of the observer. c According to the cutoff frequency ƒ c Calculate the feedback gain coefficient of the observer. K P and integral gain coefficient K i The invention utilizes an observer with the aforementioned gain coefficient to generate an acceleration estimate based on the actual generator speed, thereby generating an inertia compensation torque. By measuring the main harmonic frequencies of the rotational speed, the cutoff frequency of the observer is determined, further enabling parameter tuning and effectively improving the observer's operating performance.

Description

TECHNICAL FIELD

[0001] The application 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 system. BACKGROUND

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

[0003] With the development trend of large-scale and deep-sea of the wind power industry, the single machine capacity of the wind turbine generator system continues to increase, and higher requirements are put forward for the reliability, dynamic response capability and grid connection performance of the whole system. Due to the complex conditions of offshore test, high construction cost and long test period, more and more wind turbine generator system enterprises and research institutions tend to build a wind turbine generator system ground transmission chain test platform on land, to simulate the actual operating environment of the wind turbine generator system and carry out system-level full-power test. Such a test platform can provide controllable, reproducible and highly realistic test conditions in a land environment, and becomes a key technical means to accelerate the research and development of wind power technology and reduce the risk and cost of offshore test.

[0004] The full-power ground test platform of the wind turbine generator system usually includes a drag motor system (for simulating a wind wheel), a measured generator system, a power conversion and control system, and grid-connected equipment. The platform connects the drag motor and the generator through a mechanical coupling device and controls the load and energy feedback on the electrical side, to realize dynamic simulation of the operating state of the generator under different wind conditions.

[0005] As a core component of the ground test system, the drag motor undertakes the important function of simulating the dynamic characteristics of the real wind wheel. However, due to the absence of the actual impeller in the ground test system, the equivalent inertia of the drag motor is much lower than that of the real wind turbine impeller, so how to accurately simulate the inertia characteristics of the wind wheel becomes a technical bottleneck restricting the effectiveness of the ground test system.

[0006] At present, the inertia algorithm compensation is the mainstream inertia simulation method, which introduces an acceleration signal through a differential element to further calculate the equivalent torque of the wind wheel inertia. However, this element will amplify high-frequency harmonics, which is easy to cause resonance phenomenon in actual operation, seriously affecting the stability of the system. In order to solve this problem, a Luenberger observer is introduced in the prior art to replace the differential element to filter out high-frequency harmonics, so as to realize effective measurement of the acceleration signal. The observer adjusts the compensation amount in real time according to the generator speed through a feedback corrector, so that the observed speed can track the actual speed, thereby avoiding the instability problem to a certain extent. Among them, the selection of the feedback gain coefficient K P is a key problem. The feedback gain coefficient K PToo large, although it can improve the tracking speed of the observer to the speed, but will introduce high harmonics, affect the stability of the system, feedback gain coefficient K P Too small, the tracking speed of the observer will slow down, resulting in the observed speed unable to track the actual speed in time, unable to achieve accurate inertia simulation. In addition, the selection of Luenberger observer cutoff frequency will also affect the effectiveness of the inertia compensation system.

[0007] In summary, the parameter setting of Luenberger observer has a crucial influence on the accuracy of inertia simulation and the stability of the system. However, there is currently a lack of effective parameter setting method, resulting in the precision of inertia simulation and the stability of the system cannot be effectively guaranteed. SUMMARY

[0008] In order to solve the above problems, the present application proposes an inertia compensation method and system for a full-power ground test platform of a wind turbine generator set. The present application determines the cutoff frequency of the Luenberger observer by measuring the main harmonic frequency of the speed, further realizes the parameter setting, and effectively improves the operation performance of the observer.

[0009] According to some embodiments, the present application adopts the following technical solutions:

[0010] An inertia compensation method for a full-power ground test platform of a wind turbine generator set, comprising the following steps:

[0011] 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 ;

[0012] According to the cutoff frequency , calculate the feedback gain coefficient K P and the integral gain coefficient K i ;

[0013] Using the observer with the above gain coefficients, generate acceleration estimates according to the actual generator speed, and further generate inertia compensation torque.

[0014] As an optional implementation, the process of calculating the feedback gain coefficient of the observer according to the cutoff frequency K P includes: .

[0015] As an optional implementation, the process of calculating the integral gain coefficient of the observer according to the cutoff frequency Ki The process comprises: .

[0016] As an alternative embodiment, the observer is a Luenberger observer.

[0017] As an alternative embodiment, the process of generating the acceleration estimation value according to the actual generator speed using the observer with the gain coefficient comprises: embedding the observer with the gain coefficient into an inertia simulation control system, inputting the actual generator speed, and outputting the acceleration estimation value.

[0018] As an alternative embodiment, it further comprises correcting the test unit torque using the product of the acceleration signal output by the observer and the inertia difference value, so that the equivalent inertia of the drag motor matches the real wind turbine impeller.

[0019] As a further embodiment, the process of correcting the test unit torque comprises: introducing the acceleration signal through the observer, obtaining the compensation torque by multiplying the inertia compensation difference value, and superimposing the wind turbine aerodynamic torque to generate the frequency converter torque control signal to act on the drag motor to simulate the actual impeller output torque.

[0020] An inertia compensation system of a full-power ground test platform of a wind turbine generator set, comprising:

[0021] A cutoff frequency setting module configured to obtain wind turbine ground test data without inertia simulation, extract the main harmonic frequency of the speed from the data, and set the frequency as the cutoff frequency of the observer ;

[0022] A gain coefficient calculation module configured to calculate the feedback gain coefficient of the observer and the integral gain coefficient K P according to the cutoff frequency K i ;

[0023] An inertia compensation torque generation module configured to generate an acceleration estimation value according to the actual generator speed using the observer with the gain coefficient, and further generate an inertia compensation torque.

[0024] A terminal device comprising a processor and a computer readable storage medium, the processor being configured to implement instructions; the computer readable storage medium is configured to store a plurality of instructions, the instructions being adapted to be loaded and executed by the processor to perform the steps in the method.

[0025] A wind power control system comprising a processor and a computer readable storage medium, the processor being configured to implement instructions; the computer readable storage medium is configured to store a plurality of instructions, the instructions being adapted to be loaded and executed by the processor to perform the steps in the method.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] The present application extracts the cut-off frequency ƒ c The observer parameters are dynamically adjusted, and the blindness of artificial experience parameter adjustment is avoided.

[0028] The present application limits the phase delay by the mathematical derivation of the gain coefficient K i The mathematical derivation limits the phase delay, considers the tracking speed and harmonic suppression, and can be calculated according to the cut-off frequency only, and the overall process is simple.

[0029] The low-pass characteristics of the observer are optimized, the high-frequency noise filtering capability is enhanced, the system anti-interference performance is strengthened, and the stability of the system is improved.

[0030] In order to make the above-mentioned purposes, characteristics and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0031] The drawings accompanying the specification form a part of the present application and serve to provide a further understanding of the present application, the exemplary embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application.

[0032] Figure 1 is an inertia compensation control block diagram based on a differential element in the prior art;

[0033] Figure 2 is an inertia compensation control scheme based on a Luenberger observer in an embodiment;

[0034] Figure 3 is a Bode diagram corresponding to an embodiment;

[0035] Figure 4 is a schematic diagram of the inertia compensation control effect under the optimal parameters in an embodiment;

[0036] Figure 5 is a schematic diagram of the inertia compensation control effect when the optimal parameters are increased in an embodiment;

[0037] Figure 6 is a schematic diagram of the inertia compensation control effect when the optimal parameters are reduced in an embodiment. DETAILED DESCRIPTION

[0038] The present application will be further described below in combination with the drawings and embodiments.

[0039] It should be noted that the following detailed description is intended to provide further description of the application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0040] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0041] Embodiment One

[0042] An inertia compensation method for a full-power ground test platform of a wind turbine generator, comprising the following steps:

[0043] Obtaining wind turbine ground test data without inertia simulation, extracting the main harmonic frequency of the rotational speed, and setting the frequency as the cutoff frequency of an observer (i.e., a Luenberger observer) ;

[0044] According to the cutoff frequency , calculating the feedback gain coefficient of the observer K P and the integral gain coefficient K i ;

[0045] Using the observer with the above gain coefficients to generate an acceleration estimation value according to the actual generator rotational speed, and further generating an inertia compensation torque.

[0046] According to the cutoff frequency , calculating the feedback gain coefficient of the observer K P The process includes: .

[0047] According to the cutoff frequency , calculating the integral gain coefficient of the observer K i The process includes: .

[0048] Using the observer with the above gain coefficients to generate an acceleration estimation value according to the actual generator rotational speed, the process includes embedding the observer with the above gain coefficients into an inertia simulation control system, inputting the actual generator rotational speed, and outputting the acceleration estimation value.

[0049] Also included is a product of the acceleration signal and the inertia difference value using the observer output, which corrects the drag motor torque to match the equivalent inertia to the real fan impeller.

[0050] The process of correcting the test machine set torque includes: introducing the acceleration signal through the observer, multiplying the inertia compensation difference value to obtain the compensation torque, and superimposing the fan aerodynamic torque to generate the frequency converter torque control signal to act on the drag motor to simulate the actual impeller output torque.

[0051] The following will be described in detail and related derivation.

[0052] This embodiment selects the ground test research scene of offshore wind power fan, selects permanent magnet direct drive wind turbine as the research target, and according to the actual operation equation of offshore wind turbine and the motion equation of offshore wind turbine ground test, the following equation can be obtained:

[0053] (1)

[0054] (2)

[0055] In the formula: T r is the mechanical torque of the actual fan, T g is the electromagnetic torque of the fan, T s is the mechanical torque of the test fan, ω g is the speed of the actual fan, ω s is the speed of the test fan.

[0056] In order to realize the simulation of the actual dynamic performance of the fan, the speeds of the two are the same, that is ω g is equal to ω s , and the following equation is obtained by subtracting the two equations:

[0057] (3)

[0058] The left side of the above equation represents the torque reference value that the ground test motor needs to output: the first part of the right side of the equation represents the aerodynamic torque actually output by the wind turbine, and the second part represents the virtual compensation torque compensated by the transmission shaft acceleration signal.

[0059] The inertia compensation control scheme based on the differential element and the Luenberger observer is as follows: Figure 1 and Figure 2As shown, the differential element is replaced by a Luenberger observer in the embodiment to reduce the influence of high-order harmonics on the system caused by the differential element and improve the stability and effectiveness of inertia compensation control.

[0060] The control system introduces the acceleration signal through the observer, further obtains the compensation torque by multiplying the inertia compensation difference, and finally superimposes the fan aerodynamic torque to generate the inverter torque control signal to act on the drag motor to simulate the actual impeller output torque.

[0061] Figure 2 The forward channel part of the observer is a torque compensation loop, and the feedback corrector adjusts the compensation amount according to the generator speed and time to make the observed speed track the actual speed, so as to ensure accurate acceleration estimation in the presence of noise and other disturbances in the system model.

[0062] In order to ensure that the Luenberger observer can accurately track the acceleration of the unit, a larger feedback gain coefficient K P However, if the feedback gain coefficient of the observer is too large, high-order harmonics will be introduced, which will lose the significance of using the Luenberger observer. If the feedback gain coefficient of the observer is too small, the observed speed will be difficult to track the actual speed, and the inertia simulation of the fan will also be difficult to achieve.

[0063] The transfer function of the Luenberger observer is as shown in formula (4), and the corresponding Bode diagram is as shown in Figure 4 For the speed signal, the observer is equivalent to a low-pass filter that filters the above harmonics with a cutoff frequency of ƒ c . c= K p (rad / s), further, it is confirmed that K p , the minimum phase error of 36.87 degrees can be achieved by calculating K i , that is, the minimum delay time of the Luenberger observer is (36.87 / 360) / .

[0064] The finally determined optimal Luenberger observer parameters are:

[0065] The feedback gain coefficient ;

[0066] The integral gain coefficient .

[0067] (4)

[0068] The ground test of the fan in the embodiment needs to simulate the normal fluctuation of the fan speed in order to realize dynamic simulation of the fan. That is, as long as the cut-off frequency of the observer is greater than the main fluctuation frequency of the fan speed, the accuracy of the inertia simulation can be ensured. At the same time, the system inertia does not affect the frequency of the speed harmonic, so the fan ground test without inertia simulation can be carried out to determine the cut-off frequency , and the parameters of the Luenberger observer are further adjusted according to the optimal parameters.

[0069] In order to verify the feasibility and correctness of the wind turbine simulation scheme using the Luenberger observer with optimal parameters, a wind power simulation system simulation model is established in the Matlab / Simulink environment, and an inertia simulation experiment platform of a 2MW permanent magnet direct drive fan is built. The total inertia of the fan is set to 106kg˙m 2 , the ratio of the actual inertia to the virtual inertia is set to 1:19, the fan operates in the MPPT interval, the wind speed rises from 9m / s to 10m / s, and the effectiveness and accuracy of the virtual inertia are verified by observing the tracking state of the fan speed and the steady-state harmonic of the speed. ω1 is the actual running speed of the fan, and ω2 is the speed of the fan with inertia simulation. The harmonic frequency of the fan speed is 29HZ under the test condition without inertia simulation. According to the optimal parameters of the Luenberger observer proposed, K P =182.2、 K i =16600.7.

[0070] The experimental results of the Luenberger observer with optimal parameters are shown in Figure 4 , ω1 is the actual running speed of the fan, and ω2 is the speed of the fan with inertia simulation. By comparing the tracking state of the fan speed climbing and the steady-state harmonic of the fan, it is found that the speed of the fan with inertia simulation is basically consistent with the actual fan speed.

[0071] In order to compare the effectiveness of the designed optimal parameters, the simulation test is carried out by increasing the value of Figure 5 K P , K i It can be found that due to the excessive accuracy of the Luenberger, high frequency harmonics are introduced. By observing the experimental results, it can be found that there is a large error between the speed of the fan with inertia simulation and the actual fan speed, and the virtual inertia cannot effectively represent the state of the fan speed. As shown in Figure 6 , the value of K P , K ​i The simulation test is performed with the value of 0.1. It can be found that the steady-state harmonic speed of tracking the fan speed is insufficient due to the slow tracking speed of the Luenberger observer, although the error of the speed is not large as a whole. However, it can be found by observing the experimental results that the too small value of the gain coefficient will cause the harmonic amplitude of the fan to increase obviously, and the real fan speed state cannot be simulated. K P 、 K i The value of the gain coefficient will cause the harmonic amplitude of the fan to increase obviously, and the real fan speed state cannot be simulated.

[0072] Embodiment Two

[0073] An inertia compensation system of a full-power ground test platform of a wind turbine generator set, comprising:

[0074] A cutoff frequency setting module configured to obtain fan 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 ;

[0075] A gain coefficient calculation module configured to calculate the feedback gain coefficient and the integral gain coefficient K of the observer according to the cutoff frequency P ; K i ;

[0076] An inertia compensation torque generation module configured to generate an acceleration estimation value according to the actual generator speed by using the observer with the above gain coefficients, and further generate an inertia compensation torque.

[0077] Embodiment Three

[0078] A terminal device comprising a processor and a computer readable storage medium, the processor being configured to implement instructions; the computer readable storage medium is configured to store a plurality of instructions, the instructions being adapted to be loaded and executed by the processor to implement the steps in the method of embodiment one.

[0079] Embodiment Four

[0080] A wind power control system comprising a processor and a computer readable storage medium, the processor being configured to implement instructions; the computer readable storage medium is configured to store a plurality of instructions, the instructions being adapted to be loaded and executed by the processor to implement the steps in the method of embodiment one.

[0081] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In a software embodiment, the methods can be tangibly embodied in a machine-readable storage medium having stored thereon instructions that can be used to program a computer to perform any of the methods. The software implementation can be for example, in a modulated data signal such as a carrier wave or other transport mechanism, or a computer readable storage medium.

[0082] The present application is described in reference to the drawings, which are as follows: Figure 1 Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flowsheet block or blocks.

[0083] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart or flowsheet block or blocks. Figure 1 Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flowsheet block or blocks.

[0084] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flowsheet block or blocks. Figure 1 Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flowsheet block or blocks.

[0085] The application described herein is to be considered as illustrative only and the disclosure is not intended to be limited to the forms disclosed herein, but is capable of change and modification within the scope of the application. Accordingly, various modifications can be made in the embodiments exemplified in the application without departing from the scope and spirit of the application.

[0086] ​​​The above describes the specific embodiments of the present application in combination with the drawings, but is not a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications or variations made by those skilled in the art on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. An inertia compensation method for a full-power ground test platform for wind turbines, characterized in that, Includes the following steps: Obtain ground test data of the wind turbine from inertia-free simulation, extract the main harmonic frequencies of the rotational speed, and set these frequencies as the cutoff frequency of the observer. ; According to the cutoff frequency Calculate the feedback gain coefficient of the observer. K P and integral gain coefficient K i According to the cutoff frequency Calculate the feedback gain coefficient of the observer. K P The process includes: According to the cutoff frequency Calculate the integral gain coefficient of the observer. K i The process includes: ; Using an observer with the aforementioned gain coefficient, an acceleration estimate is generated based on the actual generator speed, which in turn generates an inertia compensation torque.

2. The inertia compensation method for a full-power ground test platform for wind turbines as described in claim 1, characterized in that, The observer is a Luneburger observer.

3. The inertia compensation method for a full-power ground test platform for wind turbines as described in claim 1, characterized in that, The process of generating an acceleration estimate based on the actual generator speed using an observer with the aforementioned gain coefficient includes: embedding the observer with the aforementioned gain coefficient into the inertia simulation control system, with the actual generator speed as the input and the acceleration estimate as the output.

4. The inertia compensation method for a full-power ground test platform for wind turbines as described in any one of claims 1-3, characterized in that, It also includes using the product of the acceleration signal output by the observer and the difference in inertia to correct the torque of the test unit, so that the equivalent inertia of the system matches that of the real wind turbine impeller.

5. The inertia compensation method for a full-power ground test platform for wind turbines as described in claim 4, characterized in that, 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 the compensation torque, and superimposing it with the aerodynamic torque of the fan to generate a frequency converter torque control signal to drive the motor to simulate the actual impeller output torque.

6. An inertia compensation system for a full-power ground test platform for wind turbine generators, characterized in that, include: The cutoff frequency setting module is configured to acquire ground test data of wind turbines from inertia-free simulations, extract the main harmonic frequencies of the rotational speed, and set these frequencies as the cutoff frequency of the observer. ; The gain coefficient calculation module is configured to calculate based on the cutoff frequency. Calculate the feedback gain coefficient of the observer. K P and integral gain coefficient K i According to the cutoff frequency Calculate the feedback gain coefficient of the observer. K P The process includes: According to the cutoff frequency Calculate the integral gain coefficient of the observer. K i The process includes: ; The inertia compensation torque generation module is configured to generate an acceleration estimate based on the actual generator speed using an observer with the aforementioned gain coefficient, and then generate the inertia compensation torque.

7. A terminal device, characterized in that, It includes a processor and a computer-readable storage medium, the processor being used to implement various instructions; the computer-readable storage medium being used to store a plurality of instructions adapted to be loaded by the processor and executed in the steps of the method of any one of claims 1-5.

8. A wind power control system, characterized in that, The system includes the system of claim 6, or includes a processor and a computer-readable storage medium, the processor being configured to implement the instructions; the computer-readable storage medium being configured to store a plurality of instructions adapted to be loaded by the processor and executed to perform the steps of the method of any one of claims 1-5.

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