A wind turbine current control method and device based on disturbance compensation and parameter identification

Abstract

The application discloses a wind turbine current control method based on disturbance compensation and parameter identification, comprising the following steps: S101, using a high-frequency signal injection method to perform parameter identification; S102, obtaining stator current components and stator voltage components of the wind turbine through parameter identification; S103, performing coordinate transformation on the stator current components and the stator voltage components to obtain a dq-axis estimation coordinate equation; S104, using the dq-axis estimation coordinate equation to calculate an expression containing angle error information; S105, performing mathematical transformation on the angle error information expression to obtain a novel angle and speed estimator, and realizing a novel positionless control method based on the estimator; and S106, performing error compensation on d-axis and q-axis current loops to eliminate position estimation error disturbance. The application can eliminate position estimation error disturbance, thereby maintaining excellent dynamic performance and steady-state accuracy of wind turbine current control.

Description

Technical Field

[0001] This invention belongs to the field of wind turbine control technology, specifically relating to a wind turbine current control method and device based on disturbance compensation and parameter identification. Background Technology

[0002] In harsh environments, the position sensors of wind turbines are prone to malfunction, leading to operational failures. Therefore, ensuring stable operation of wind turbines even when position sensors fail or are unavailable is of significant practical value. Position and speed estimators need to be designed to accurately estimate the position and speed of the wind turbine. However, under conditions of wide-range speed variations and uncertain wind turbine parameters, using traditional phase-locked loop (PLL) methods to estimate rotor position and speed results in severe instability problems in the wind turbine control system. Furthermore, position estimation errors and uncertain wind turbine parameters significantly impact the steady-state accuracy of the wind turbine's current control.

[0003] Therefore, the existing technology has the following problems: due to the integrated packaging of wind turbine and controller, it is difficult to use instruments or additional test hardware to detect wind turbine parameters. Furthermore, when using rotor position and speed estimators based on traditional phase-locked loops for positionless control, it is impossible to maintain excellent dynamic performance and steady-state accuracy under large speed variations. Moreover, position estimation error disturbances and uncertain wind turbine parameters will seriously affect the steady-state accuracy of wind turbine current control. Summary of the Invention

[0004] To overcome the shortcomings of the existing technology, the present invention aims to provide a wind turbine current control method and device based on disturbance compensation and parameter identification. This method and device can solve the serious instability problem of wind turbine control system using traditional phase-locked loop method to estimate rotor position and speed under the conditions of large-range speed variation and parameter uncertainty of wind turbine. It can also eliminate position estimation error disturbance, thereby maintaining the excellent dynamic performance and steady-state accuracy of wind turbine current control.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A wind turbine current control method based on disturbance compensation and parameter identification includes the following steps;

[0007] S101: Identification of resistance and inductance parameters of wind turbine generators using high-frequency signal injection method;

[0008] S102: Obtain the stator current component and stator voltage component of the wind turbine generator;

[0009] S103: Perform coordinate transformation on the stator current component and stator voltage component to obtain the estimated coordinate system equation for the dq axis;

[0010] S104: Using the dq axis to estimate the coordinate system equation, calculate the expression containing angular error information;

[0011] S105: Perform a mathematical transformation on the angle error information expression to obtain a novel angle and speed estimator, and implement a novel positionless control method based on this estimator;

[0012] S106: Performs error compensation on the d-axis and q-axis current loops to eliminate position estimation error disturbances and improve the stability and dynamic performance of the system.

[0013] In step S101, the resistor and inductor are identified respectively:

[0014] Resistance identification: Identification is performed using the voltmeter-ammeter method. Connect phase A of the fan to the positive terminal and phases B and C to the negative terminal. Apply a DC voltage and calculate the resistance value directly using Ohm's law based on the applied voltage and the sampled current.

[0015] The specific calculation expression is as follows:

[0016]

[0017] Where U1 and U2 are the voltage amplitudes at the previous and next time points, and I1 and I2 are the current amplitudes at the previous and next time points;

[0018] Inductance identification: A high-frequency voltage vector is injected into the dq axis, and the inductance is calculated based on the mathematical model and current response. The specific calculation expression is as follows:

[0019]

[0020] Among them, U inv I represents the amplitude of the high-frequency voltage vector. dh ω represents the amplitude of the high-frequency current component. h The frequency of the injected high-frequency voltage vector.

[0021] Specifically, S102 is as follows:

[0022] Obtain the stator current component i of the wind turbine a i b i c and stator voltage component u a u b u c And by transforming the coordinates, the estimated current component i in the rotating coordinate system is obtained. d i q and voltage component u d u q ;

[0023] Among them, the stator current component i α and i β Stator voltage component u α and u β All are components in a two-phase stationary coordinate system (αβ coordinate system).

[0024] Specifically, the process of obtaining the stator current component of the current control cycle includes:

[0025] To obtain the phase current of each phase in the current control cycle, specifically, the sum of the phase currents of any two phases, such as i. a and i b Then based on i a +i b +i c =0 Calculate i c For phase current i a i b i c The stator current components i in the two-phase stationary coordinate system are obtained by transformation. α and i β The calculation formula is as follows:

[0026]

[0027] Specifically, the process of obtaining the stator voltage components of the current control cycle includes:

[0028] Obtain the DC bus voltage U of the current control cycle dc and the current switch state S j (j = a, b, c);

[0029] Reconstruct the three-phase voltage based on the DC bus voltage and the current switch state;

[0030]

[0031] Regarding the above three-phase phase voltage U a U b U c The stator voltage component U in the two-phase stationary coordinate system is obtained by transformation. α and U β The specific expression is:

[0032]

[0033] Specifically, S103 is:

[0034] The coordinate system equations for the dq axes are estimated using coordinate transformation:

[0035]

[0036] in and Estimate the current components in the coordinate system for dq, where R and L are the stator resistance and the quadrature-direct axis inductance, respectively. and To estimate the voltage components in the coordinate system for dq, ψ f It is a permanent magnet flux chain. This is an estimated value for the electric angular velocity. This represents the electrical angle error component.

[0037] Specifically, S104 is:

[0038] Specifically as follows:

[0039]

[0040] Specifically, S105 is:

[0041] The specific expression for the mathematical transformation is:

[0042]

[0043] The specific expressions for the angle and speed estimators are as follows:

[0044]

[0045] Where, ψ f Let ω be the magnetic flux linkage and ω be the electric angular velocity. The electrical angle error component, electrical angle estimate, k is the estimated electric angular velocity. p and k i These are design parameters.

[0046] Specifically, S106 is:

[0047] Error interference term in d-axis current loop compensation The specific expression is:

[0048]

[0049] The final result is:

[0050]

[0051] Similarly, in the q-axis current loop compensation error interference term The specific expression is:

[0052]

[0053] The final result is:

[0054]

[0055] A high-precision wind turbine current control device based on position estimation error compensation and parameter identification includes a current and voltage acquisition module, a filtering module, a signal amplification module, an analog-to-digital conversion module, and an angle and speed estimation module.

[0056] The current and voltage acquisition module is used to acquire three-phase stator current and three-phase stator voltage. The acquired voltage and current signals are processed by a filtering module, a signal amplification module, an analog-to-digital conversion module, and a speed estimation module. The speed estimation module estimates the angle and angular velocity.

[0057] The current and voltage acquisition module is based on the Hall effect and is installed on the three phase lines a, b, and c of the wind turbine.

[0058] The microcontroller unit (MCU or DSP) executes the above-described method according to the steps to calculate the position and speed of the wind turbine.

[0059] The beneficial effects of this invention are:

[0060] This invention proposes a high-precision wind turbine current control method based on position estimation error compensation and parameter identification, and designs a corresponding hardware circuit. This method can identify resistance and inductance parameters before the wind turbine starts running, and has excellent dynamic performance and steady-state accuracy under a wide range of speed changes, avoiding oscillation and shutdown, and enabling positionless control of the wind turbine. Attached Figure Description

[0061] Figure 1 This is a flowchart of the wind turbine current control method of the present invention.

[0062] Figure 2 This is a schematic diagram of the structure of the present invention.

[0063] In the diagram: 1. Voltage and current acquisition module; 2. Filtering module; 3. Signal amplification module; 4. Analog-to-digital conversion module; 5. Angle and speed estimation module. Detailed Implementation

[0064] The present invention will now be described in further detail with reference to the accompanying drawings.

[0065] This invention eliminates the problem of difficulty in detecting wind turbine parameters using instruments or additional testing hardware. It can identify resistance and inductance parameters before the wind turbine is running and has good robustness under large speed variations, avoiding oscillations or even crashes, thus improving the dynamic performance and steady-state accuracy of wind turbines without position control.

[0066] like Figure 1As shown, the position and velocity estimation method provided in this embodiment of the invention includes the following steps:

[0067] S101: Parameter identification of wind turbine units using high-frequency signal injection method;

[0068] The identification of resistors and inductors is performed separately, using the following methods:

[0069] Resistance identification: The voltmeter-ammeter method is typically used. Phase A is connected to the positive terminal, and phases B and C are connected to the negative terminals. A DC voltage is continuously applied, and the resistance value is calculated directly using Ohm's law based on the applied voltage and the sampled current. The specific calculation expression is as follows:

[0070]

[0071] Where U1 and U2 are the voltage amplitudes at the previous and next time points, and I1 and I2 are the current amplitudes at the previous and next time points.

[0072] Inductance identification: The high-frequency injection method involves injecting a high-frequency voltage vector into the dq axis. Because the applied voltage frequency is high enough that the wind turbine will not rotate accordingly, and the voltage drop across the resistor can be ignored, the inductance is calculated based on the mathematical model and current response. The specific calculation expression is as follows:

[0073]

[0074] Among them, U inv I represents the amplitude of the high-frequency voltage vector. dh ω represents the amplitude of the high-frequency current component. h The frequency of the injected high-frequency voltage vector.

[0075] S102: Obtain the stator current component and stator voltage component of the wind turbine generator;

[0076] Among them, the stator current component i α and i β Stator voltage component u α and u β All are components in a two-phase stationary coordinate system (αβ coordinate system).

[0077] Specifically, the process of obtaining the stator current component of the current control cycle includes:

[0078] To obtain the phase current of each phase in the current control cycle, specifically, the sum of the phase currents of any two phases, such as i. a and i b Then based on i a +i b +i c =0 Calculate i c For phase current i a i b ic The stator current components i in the two-phase stationary coordinate system are obtained by transformation. α and i β The calculation formula is as follows:

[0079]

[0080] Specifically, the process of obtaining the stator voltage components of the current control cycle includes:

[0081] Obtain the DC bus voltage U of the current control cycle dc and the current switch state S j (j = a, b, c);

[0082] The three-phase voltage can be reconstructed based on the DC bus voltage and the current switch state;

[0083]

[0084] Regarding the above three-phase phase voltage U a U b U c The stator voltage component U in the two-phase stationary coordinate system is obtained by transformation. α and U β The specific expression is:

[0085]

[0086] S103: The coordinate system equation for the estimated dq axis is derived using coordinate transformation; specifically, the process of obtaining the stator voltage components of the current control cycle includes:

[0087]

[0088] make L d =L q =L,

[0089]

[0090] Finally, the simplified equations of the dq axis coordinate system are obtained:

[0091]

[0092] in: and This is an estimate of the sub-current in a rotating coordinate system. and Here, R and L are the estimated values ​​of the stator voltage in the rotating coordinate system, and R and L are the stator resistance and quadrature-axis inductance, respectively. This is an estimated value for the electric angular velocity. This represents the electrical angle error component.

[0093] S104: Using the dq axis to estimate the coordinate system equation, calculate the expression containing angular error information;

[0094] The specific calculation expression is as follows:

[0095]

[0096] S105: Perform a mathematical transformation on the angle error information expression to obtain a new angle and speed estimator, and implement a new control method based on this estimator;

[0097] The expression for angle error information is mathematically transformed, and the specific expression is as follows:

[0098]

[0099] The specific calculation formulas for the angle and speed estimator are as follows:

[0100]

[0101] in This represents the estimated electric angular velocity. k is the electrical angle error component. p and k i It is a parameter.

[0102] S106: Perform error compensation on the current loop to eliminate position estimation error disturbances and improve the stability and dynamic performance of the system. The specific steps are as follows:

[0103] Error interference term in d-axis current loop compensation The specific expression is:

[0104]

[0105] The final result is:

[0106]

[0107] Similarly, in the q-axis current loop compensation error interference term The specific expression is:

[0108]

[0109] The final result is:

[0110]

[0111] like Figure 2As shown, the wind turbine current control device provided in this embodiment of the invention includes a voltage and current acquisition module 1, a filtering module 2, a signal amplification module 3, an analog-to-digital conversion module 4, and an angle and speed estimation module 5.

[0112] The voltage and current acquisition module 1 obtains the three-phase stator current and three-phase stator voltage. The obtained signals are input to the filtering module 2, the signal amplification module 3, and the analog-to-digital conversion module 4, and then input to the angle and speed estimation module 5. The DSP or MCU runs a novel position and speed estimation algorithm to estimate the position and speed of the wind turbine. The estimated position and speed are compared with the actual position and speed of the wind turbine obtained by the encoder. The results are basically consistent. Moreover, the system has excellent dynamic performance and steady-state accuracy under a wide range of speed changes, proving that the estimation method proposed in this invention is accurate.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wind turbine generator current control method based on disturbance compensation and parameter identification, characterized in that, It comprises the following steps: S101: using high-frequency signal injection method to identify the resistance and inductance parameters of the wind turbine generator; S102: obtaining the stator current component and the stator voltage component of the wind turbine generator; S103: performing coordinate transformation on the stator current component and the stator voltage component to obtain the dq-axis estimation coordinate equation; S104: using the dq-axis estimation coordinate equation to calculate an expression containing angle error information; S105: performing mathematical transformation on the angle error information expression to obtain an angle and speed estimator, and implementing the positionless control method based on the estimator; The S105 is specifically: The specific expression of mathematical transformation is: The specific expression of the angle and speed estimator is: where ψ f is the flux linkage, ω is the electrical angular velocity, is the electrical angle error component, the electrical angle estimate, is the electrical angular velocity estimate, k p and k i are design parameters; S106: performing error compensation on the d-axis and q-axis current loops to eliminate the position estimation error disturbance; The S106 is specifically: In the d-axis current loop compensation error disturbance term The specific expression is: Finally, we get: Similarly, in the q-axis current loop compensation error disturbance term The specific expression is: Finally, we get: wherein and are the current components in the dq estimation coordinate system, R and L are the stator resistance and direct and quadrature axis inductances, and are the voltage components in the dq estimation coordinate system.

2. The wind turbine generator current control method based on disturbance compensation and parameter identification according to claim 1, characterized in that, In the S101, the resistance and inductance are identified respectively: Resistance identification: using volt-ampere method, connecting the positive electrode of phase A, the negative electrode of phase B and phase C, applying direct current voltage, and directly calculating the resistance value according to the applied voltage and the sampled current by Ohm's law; The specific calculation expression is: Wherein, U1 and U2 are the voltage amplitudes at the previous and next time, and I1 and I2 are the current amplitudes at the previous and next time; Inductance identification: injecting a high-frequency voltage vector into the dq-axis, and calculating the inductance according to the mathematical model and the current response, and the specific calculation expression is: where U inv is the high-frequency voltage vector amplitude, I dh is the high-frequency current component amplitude, ω h is the injected high-frequency voltage vector frequency.

3. The wind turbine generator current control method based on disturbance compensation and parameter identification according to claim 2, characterized in that, The S102 is specifically: Obtaining stator current components i a b c and stator voltage components u a b c and, by means of a coordinate transformation, obtaining estimated current components i d q and voltage components u d q in the estimated rotating coordinate system;​​​​​​ wherein the stator current components i α and i β , the stator voltage components u α and u β are components in a two-phase stationary coordinate system.

4. The wind turbine generator current control method based on disturbance compensation and parameter identification according to claim 3, characterized in that, The process of obtaining the stator current component of the current control period includes: Obtain the phase current of each phase in the current control cycle, and obtain the phase current i of any two phases. a and i b Then based on i a +i b +i c =0 Calculate i c For phase current i a i b i c The stator current components i in the two-phase stationary coordinate system are obtained by transformation. α and i β The calculation formula is as follows: The process of obtaining the stator voltage component of the current control period includes: acquiring a direct current bus voltage U of a current control period dc and a current switching state S j (j = a, b, c); Reconstructing the three-phase phase voltage based on the DC bus voltage and the current switching state; The three-phase phase voltages U a , U b , U c are transformed to obtain stator voltage components U α and U β in the two-phase stationary coordinate system, and the specific expressions are:

5. The wind turbine generator current control method based on disturbance compensation and parameter identification according to claim 4, characterized in that, The S103 is specifically: Using coordinate transformation to obtain the dq-axis estimation coordinate equation: wherein and is the current component in the dq estimation coordinate system, R and L are the stator resistance and direct and quadrature axis inductances, and is the voltage component in the dq estimation coordinate system, ψ f is the permanent magnet flux linkage, is the electrical angular velocity estimate, is the electrical angle error component.

6. The wind turbine generator current control method based on disturbance compensation and parameter identification according to claim 5, characterized in that, The S104 is specifically: Specifically as follows:

7. A high-precision wind turbine generator current control device based on position estimation error compensation and parameter identification for implementing the method of any one of claims 1-6, characterized in that, It comprises a current and voltage acquisition module (1), a filtering module (2), a signal amplification module (3), an analog-to-digital conversion module (4), and an angle and speed estimation module (5); The current and voltage acquisition module (1) is used to acquire three-phase stator current and three-phase stator voltage, and the acquired voltage and current signals are filtered by the filtering module (2), the signal amplification module (3), the analog-to-digital conversion module (4) and the speed estimation module (5); the speed estimation module (5) estimates the angle and angular velocity.

8. The high-precision wind turbine generator current control device based on position estimation error compensation and parameter identification according to claim 7, characterized in that, The current and voltage acquisition module (1) is installed on the three phase lines a, b and c based on the Hall effect.

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