High-magnification moment of inertia simulation method for a speed-sensorless full-power test bench of a fan

Abstract

A high-magnitude rotational inertia simulation method for a full-power test bench of a speed-sensorless wind turbine, comprising the following steps: determining the rotational inertia J of the low-speed side of the wind turbine based on the actual wind turbine model to be simulated by the full-power test bench t ; measuring the rotational inertia J of the full-power test bench itself s ; measuring the communication time delay τ of the full-power test bench, determining the time-delay order k0 based on the communication time delay τ; determining the k0-order filter parameter α of the torque compensation loop according to the time-delay order k0 d ; constructing a feedforward filter transfer function according to the above parameters. This method corrects the aerodynamic torque of the test bench by adding a feedforward filter to the aerodynamic torque calculation loop, suppressing the acceleration deviation of the existing dynamic simulation experiment system, thereby eliminating the high-frequency oscillation of the rotational speed.

Description

Technical Field

[0001] The invention relates to a high-multiple rotational inertia simulation method for a wind turbine full-power test bench without a speed sensor, and belongs to the technical field of wind turbine simulation experiments. Background Art

[0002] As wind turbines become larger and more sophisticated, they have put forward more stringent requirements for their own operating performance, such as safety, reliability, and network connectivity. It is urgent to carry out sufficient test inspections and test verifications in the model development stage. However, field tests with actual wind turbines in wind farms have the disadvantages of high test costs, harsh operating environment, high risk factor, long test cycle, and uncontrollable wind conditions. Therefore, wind power companies usually build MW-level full-power wind turbine dynamic model test benches instead of actual wind turbines, so that functional tests and performance evaluations of wind turbine power generation, control, and network-related aspects can be carried out in the laboratory, thereby ensuring the safety of scientific researchers and significantly reducing the R&D costs and shortening the R&D cycle of wind turbines.

[0003] The existing inertia compensation strategy is generally based on the speed differential method to obtain the speed acceleration to calculate the compensation torque. This method has very high requirements for speed accuracy. However, due to the low speed (0-20rpm) and large shaft radius of the large-capacity full-power test bench, and the influence of mechanical vibration and electromagnetic interference during operation, the speed encoder is difficult to install and the measurement accuracy does not meet the requirements of the speed differential method. Therefore, the existing MW-level full-power test bench generally uses a speed sensorless rotation inertia compensation strategy, which collects the test bench drive torque and electromagnetic torque, and uses the torque differential method to obtain the acceleration to calculate the compensation torque.

[0004] However, due to the communication delay in the experimental system, the system becomes unstable and oscillates. Therefore, the existing research uses a k0-order filter in the torque compensation loop to stabilize the experimental system. Although the filter can solve the stability problem of the experimental system, the experimental system still has an acceleration deviation component, which increases with the increase of the rotational inertia simulation multiple, improving the acceleration and deceleration ability of the experimental system, making it difficult for the existing experimental system to simulate the slow mechanical dynamics of the high-multiple rotational inertia fan. Under turbulent wind conditions, the experimental system will experience abnormal speed fluctuations. Summary of the invention

[0005] In order to solve the shortcomings of the prior art, the purpose of the present invention is to provide a high-multiple rotational inertia simulation method for a speed sensorless fan full-power test bench, which solves the high-frequency speed oscillation phenomenon of the speed sensorless fan full-power test bench with dynamic inertia compensation strategy in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A high - multiple moment of inertia simulation method for a sensorless full - power fan test bench, comprising the following steps:

[0008] Based on the actual fan model to be simulated by the full - power test bench, determine the moment of inertia J of the low - speed side of the fan t ;

[0009] Measure the moment of inertia J of the full - power test bench itself s ;

[0010] Measure the communication delay τ of the full - power test bench, and determine the delay order k0 based on the communication delay τ;

[0011] Determine the k0 - order filter parameter α of the torque compensation loop according to the delay order k0 d ;

[0012] Construct a feed - forward filter transfer function according to the above parameters.

[0013] Furthermore, the measurement steps of the moment of inertia J of the full - power test bench itself s include:

[0014] Send a constant command to the motor drive torque T s and the generator electromagnetic torque T g through the frequency converter, and make the unbalanced torque △T = T s - T g fixed;

[0015] Real - time collect the motor speed through the frequency converter, and use the PLC to record the motor speed ω g and fit the speed curve into a straight line through an algorithm;

[0016] Calculate the slope of the fitted straight line Substitute into the formula to obtain the moment of inertia J of the full - power test bench itself s .

[0017] Furthermore, the steps of determining the delay order k0 based on the communication delay τ include:

[0018] Real - time collect the drive torque command value T ref of the PLC and the operating torque T opr of the frequency converter, apply a step signal to the drive torque command value, and record the time τ when the operating torque T opr of the frequency converter responds to the torque command value T ref , and this time is the communication delay τ of the full - power test bench;

[0019] Substitute into the formula k0 = [τ / T] to obtain the delay order k0, where T represents the control period of the full - power fan test bench.

[0020] Further, the k0 - order filter parameter α of the aforementioned torque compensation circuit d has the following expression:

[0021]

[0022] Further, the transfer function expression of the aforementioned feed - forward filter is:

[0023]

[0024] A computer device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the aforementioned high - multiple moment of inertia simulation method for the full - power test bench of the fan are implemented.

[0025] A computer - storable medium stores a computer program. When the computer program is executed by a processor, the steps of the aforementioned high - multiple moment of inertia simulation method for the full - power test bench of the fan are implemented.

[0026] The beneficial effects achieved by the present invention:

[0027] Under the existing moment of inertia compensation strategy of the full - power test bench, the present invention only adds a feed - forward filter link. Through feed - forward correction, the high - frequency speed fluctuation phenomenon caused by the acceleration deviation component is eliminated, and the mechanical dynamics of the high - multiple moment of inertia fan is accurately simulated on the full - power test bench of the fan; the accuracy of simulating the mechanical dynamics of the high - multiple moment of inertia fan on the full - power test bench of the sensorless fan is greatly improved. Description of the Drawings

[0028] Figure 1 is the structure and schematic diagram of the full - power test bench with a feed - forward filter according to the present invention;

[0029] Figure 2 is the discrete - domain model of the full - power test system of the fan with a feed - forward filter according to the present invention;

[0030] Figure 3 is J of the present invention t = 100J s The acceleration trajectory diagram of the experimental system under turbulent wind speed under the traditional simulation method under the condition of J

[0031] Figure 4 is J of the present invention t = 100J s The speed trajectory diagram of the experimental system under turbulent wind speed under the traditional simulation method under the condition of J

[0032] Figure 5 is J of the present invention t = 100Js Acceleration trajectory diagram of the experimental system under turbulent wind speed in the experiment with a feed-forward filter under the condition;

[0033] Figure 6 This is the invention J t = 100J s Rotation speed trajectory diagram of the experimental system under turbulent wind speed in the experiment with a feed-forward filter under the condition. Specific implementation manner

[0034] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0035] This embodiment discloses a high-magnitude moment of inertia simulation method for a full-power experimental platform of a wind turbine without a speed sensor, including the following steps:

[0036] Step 1: Determine the actual wind turbine model to be simulated by the full-power experimental platform, and determine the moment of inertia J of the low-speed side of the wind turbine t ;

[0037] Step 2: Measure the moment of inertia J of the full-power experimental platform itself s ;

[0038] First, the moment of inertia of the full-power experimental platform itself can be determined by the following formula:

[0039]

[0040] In the formula: ω g is the motor speed, T s is the motor driving torque, T g is the generator electromagnetic torque.

[0041] The measurement method of the moment of inertia J of the full-power experimental platform itself s is as follows:

[0042] Step 2-1: Issue constant commands to the motor driving torque T s , generator electromagnetic torque T g through the frequency converter, and make the unbalanced torque △T = T s -T g fixed;

[0043] Step 2-2: Collect the motor speed in real time through the frequency converter, use the PLC to record the speed and fit the speed curve into a straight line through an algorithm;

[0044] Step 2-3: The slope of the fitted straight line is the motor acceleration The moment of inertia of the motor counter-rotating system of the experimental platform can be calculated according to the above formula.

[0045] Step 3: Measure the communication time delay τ of the full-power test bench and determine the time delay order k0;

[0046] Step 3-1: First, collect the drive torque command value T of the PLC in real time ref and the operating torque T of the frequency converter opr , apply a step signal to the drive torque command value, and record the time τ when the operating torque T of the frequency converter opr responds to the torque command value T ref . This time is the communication time delay τ of the full-power test bench.

[0047] Step 3-2: Determine the time delay order k0. The specific formula is:

[0048] k0 = [τ / T]

[0049] where T represents the control period of the full-power test bench of the fan.

[0050] Step 4: Determine the k0-order filter parameter α of the torque compensation loop d , and the specific value of α d is as follows:

[0051]

[0052] where J t is the moment of inertia of the low-speed side of the fan, and J s is the moment of inertia of the full-power test bench itself.

[0053] Step 5: According to the above parameters, add a feedforward filter to the pneumatic torque calculation loop of the full-power test bench of the fan so that the full-power test bench can accurately simulate a high-magnitude moment of inertia fan. The formula used for the feedforward filter is:

[0054]

[0055] where α d is the k0-order filter parameter of the torque compensation loop.

[0056] The present invention will be further described in detail below with reference to the embodiments:

[0057] To verify the effectiveness of the method for improving the simulation multiple of the moment of inertia of the full-power test bench of a speed-sensorless fan based on feedforward compensation of the present invention, an experimental verification is carried out based on the established full-power test bench of the fan. The main structure and principle schematic diagram are as Figure 1As shown in the figure, the experimental system consists of a motor drag system composed of an asynchronous motor and a synchronous generator, an industrial-grade motor drive based on VACON, a grid-connected frequency converter, and a digital control system based on the German Beckhoff PLC. Among them, the mathematical control system completes the generation of turbulent wind speed and the calculation of aerodynamic torque, electromagnetic torque, and compensation torque. The feed-forward filter is in the aerodynamic torque calculation loop. The PLC sends the calculated motor drive torque command and electromagnetic torque command to the frequency converter through the industrial fieldbus to perform servo control on the motor. The parameters of the full-power test bench are shown in Table 1:

[0058] Table 1 Parameters of the full-power test bench

[0059]

[0060]

[0061] Among them, the calculation formula for electromagnetic torque is:

[0062]

[0063] The fan adopts the maximum power point tracking (MPPT) control method. This method uses this power curve as the electromagnetic power command of the wind turbine, enabling the wind turbine to operate on the optimal power curve, where k opt is the optimal torque gain coefficient.

[0064] For Comparative Example I: Using turbulent wind speed as the input, under the condition that the rotational inertia simulation multiple is 100 times, as Figure 3 、 Figure 4 shown, the rotational speed of the full-power test bench applying the existing inertia compensation method shows significant abnormal rotational speed fluctuations, and the acceleration is much greater than that of the actual fan.

[0065] Example II: Applying the high-multiple rotational inertia simulation method of the sensorless fan full-power test bench of the present invention, as Figure 1 shown, the specific implementation is as follows:

[0066] 1. Determine the rotational inertia J of the fan to be simulated t to be 72 kgm 2 ;

[0067] 2. Measure the rotational inertia J of the full-power test bench itself s to be 0.72 kgm 2 ;

[0068] 3. Measure that the communication time delay τ of the full-power test bench is 120 ms and the test bench sampling period T is 40 ms, and determine that the time delay order k0 is 3;

[0069] 4. Determine the k0 - order filter parameter α of the torque compensation circuit d , in this embodiment, α d takes the value of 0.99;

[0070] 5. Add a feed - forward filter to the pneumatic torque calculation branch of the full - power test bench.

[0071] The experimental results of applying the high - multiple moment of inertia simulation method based on feed - forward correction of the present invention are as Figure 5 , Figure 6 shown. The rotational speed of the full - power test bench can coincide well with the actual wind turbine rotational speed. This method eliminates the abnormal rotational speed phenomenon of the full - power test bench and improves the accuracy of simulating the rotational speed dynamics.

[0072] In summary, the high - multiple moment of inertia simulation method based on a speed - sensorless wind turbine full - power test bench proposed by the present invention uses a feed - forward filter to cancel the acceleration deviation component of the drive system, eliminates the abnormal fluctuation phenomenon of the rotational speed of the full - power test bench, and realizes the accurate simulation of the mechanical dynamics of a high - multiple moment of inertia wind turbine by the wind turbine full - power test bench.

[0073] This disclosure is described with reference to the methods according to the embodiments of the present disclosure. It should be understood that the specified functions can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general - purpose computer, a special - purpose computer, an embedded processor, or other programmable data - processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data - processing devices generate a device for implementing the specified functions in the process.

[0074] These computer program instructions can also be stored in a computer - readable memory that can direct a computer or other programmable data - processing devices to work in a specific manner, such that the instructions stored in the computer - readable memory generate a manufactured article including an instruction device that implements the specified functions in the process.

[0075] The above - mentioned are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A high - multiple moment of inertia simulation method for a full - power test bench of a speed - sensorless fan, characterized in that, It includes the following steps: Determine the rotational inertia J of the low-speed side of the fan based on the actual fan model to be simulated by the full-power test bench t ; Full-power test bench's own moment of inertia J s , and the measurement steps include: The drive torque T of the motor is controlled by a frequency converter s and the electromagnetic torque T of the generator g are given constant commands so that the unbalanced torque ΔT = T s - T g remains fixed; The motor speed is collected in real time through a frequency converter, and the PLC is used to record the motor speed ω g and fit the speed curve into a straight line through an algorithm; Calculate the slope of the fitting straight line Substitute into the formula Obtain the moment of inertia J of the full-power test bench itself s ; Measure the communication time delay τ of the full-power test bench, and determine the time delay order k0 based on the communication time delay τ. The steps include: Real-time collect the drive torque command value T of the PLC ref and the operating torque T of the frequency converter opr , apply a step signal to the drive torque command value, and record the operating torque T of the frequency converter opr responding to the torque command value T ref The time τ, this time is the communication time delay τ of the full-power test bench; Substitute into the formula k0 = [τ / T] to obtain the time delay order k0, where T represents the control period of the fan full-power test bench; Determine the k0-order filter parameter α of the torque compensation loop according to the time-delay order k0 d ; The expression formula is as follows: According to the above parameters, construct the transfer function of the feedforward filter to eliminate high-frequency fluctuations. The expression is:

2. A computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method described in any one of claims 1.

3. A computer - readable storage medium, on which a computer program is stored, characterized in that, When the computer program is executed by the processor, it implements the steps of the method described in any one of claims 1.

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