Wind turbine generator current control method and device based on disturbance compensation and parameter identification

Abstract

The invention discloses a wind turbine generator current control method based on disturbance compensation and parameter identification. S101, parameter identification is carried out by using a high-frequency signal injection method; s102, obtaining a stator current component and a stator voltage component of the wind turbine generator through parameter identification; s103, performing coordinate transformation on the stator current component and the stator voltage component to obtain a dq axis estimation coordinate system equation; s104, calculating by using the dq axis estimation coordinate system equation to obtain an expression containing angle error information; s105, performing mathematical transformation on the angle error information expression to obtain a novel angle and rotating speed estimator, and realizing a novel position-free control method based on the estimator; and S106, error compensation is carried out on the d-axis current loop and the q-axis current loop, and position estimation error disturbance is eliminated. According to the method, the position estimation error disturbance can be eliminated, so that excellent dynamic performance and steady-state precision of wind turbine generator current control are kept.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind turbine control, and in particular relates to a method and a device for controlling a current of a wind turbine based on disturbance compensation and parameter identification. Background Art

[0002] In harsh environments, the position sensor of a wind turbine is prone to malfunction, which can cause the wind turbine to fail to operate normally. Therefore, it is of great application value to ensure the stable operation of the wind turbine when the wind turbine position sensor fails or there is no position sensor. This requires the design of a position and speed estimator to accurately estimate the position and speed of the wind turbine. However, under conditions where the speed varies over a large range and the parameters of the wind turbine are uncertain, the wind turbine control system has serious instability problems when estimating the rotor position and speed using the traditional phase-locked loop method, and the position estimation error disturbance and uncertain wind turbine parameters will seriously affect the steady-state accuracy of the wind turbine current control.

[0003] Therefore, the problems existing in the prior art are: due to the integrated packaging of the wind turbine and the controller, it is difficult to detect the wind turbine parameters using instruments or additional test hardware, and when position-free control is performed using a rotor position and speed estimator based on a traditional phase-locked loop, it is impossible to maintain excellent dynamic performance and steady-state accuracy under a large range of speed changes, and position estimation error disturbances and uncertain wind turbine parameters will seriously affect the steady-state accuracy of the wind turbine current control. Summary of the invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a wind turbine current control method and device based on disturbance compensation and parameter identification. The method and device can solve the serious instability problem of the wind turbine control system using the traditional phase-locked loop method to estimate the rotor position and speed under the conditions where the wind turbine speed changes over a wide range and the parameters are uncertain, and can eliminate the position estimation error disturbance, thereby maintaining the excellent dynamic performance and steady-state accuracy of the wind turbine current control.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

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

[0007] S101: Identify the resistance and inductance parameters of wind turbines using a high-frequency signal injection method;

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

[0009] S103: performing coordinate transformation on the stator current component and the stator voltage component to obtain a dq-axis estimation coordinate system equation;

[0010] S104: using the dq axis estimation coordinate system equation to calculate and obtain an expression containing angle error information;

[0011] S105: mathematically transforming the angle error information expression to obtain a novel angle and speed estimator, and implementing a novel position-free control method based on the estimator;

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

[0013] In S101, the resistance and inductance are identified respectively:

[0014] Resistance identification: Use the volt-ampere method to identify, connect phase A of the fan to the positive pole, phases B and C to the negative pole, apply a DC voltage, and directly calculate the resistance value using Ohm's law based on the applied voltage and sampled current;

[0015] The specific calculation expression is:

[0016]

[0017] Among them, U1 and U2 are the voltage amplitudes at the previous and next moments, and I1 and I2 are the current amplitudes at the previous and next moments;

[0018] Inductance identification: Inject a high-frequency voltage vector into the dq axis and calculate the inductance based on the mathematical model and current response. The specific calculation expression is:

[0019]

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

[0021] The S102 is specifically:

[0022] Get the stator current component i of the wind turbine a 、i b 、i c and the stator voltage component u a 、u b 、u c , and obtain the estimated current component i in the rotating coordinate system through coordinate transformation 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 They are all components in the 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] Get the phase current of each phase in the current control cycle. Specifically, you can get the phase current of any two phases, such as i a and i b , then based on i a +i b +i c =0Calculate i c , for phase current i a 、i b 、i c Transform to obtain the stator current component i in the two-phase stationary coordinate system α and i β , and its calculation formula is:

[0026]

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

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

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

[0030]

[0031] For the above three-phase phase voltage U a , U b , U c Transform to obtain the stator voltage component U in the two-phase stationary coordinate system α and U β , the specific expression is:

[0032]

[0033] The S103 is specifically:

[0034] The coordinate system equation of the dq axis estimation is obtained by coordinate transformation:

[0035]

[0036] in and is the current component in the dq estimation coordinate system, R and L are the stator resistance and the AC and DC axis inductance, and is the voltage component in the dq estimation coordinate system, ψ f is the permanent magnet flux, is the estimated value of electrical angular velocity, is the electrical angle error component.

[0037] The S104 is specifically:

[0038] The details are as follows:

[0039]

[0040] The S105 is specifically as follows:

[0041] The specific expression of mathematical transformation is:

[0042]

[0043] The specific expressions of the angle and speed estimator are:

[0044]

[0045] Among them, ψ f is the magnetic flux, ω is the electrical angular velocity, is the electrical angle error component, The estimated electrical angle, is the estimated value of electrical angular velocity, k p and k i is a design parameter.

[0046] The S106 is specifically as follows:

[0047] In the d-axis current loop compensation error disturbance term The specific expression is:

[0048]

[0049] Finally, we get:

[0050]

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

[0052]

[0053] Finally, we get:

[0054]

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

[0056] The current and voltage acquisition module is used to collect three-phase stator current and three-phase stator voltage. The collected voltage and current signals are passed through 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 fan;

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

[0059] Beneficial effects of the present invention:

[0060] The present 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. The method can identify resistance and inductance parameters before the wind turbine is operated, and has excellent dynamic performance and steady-state accuracy when the speed changes over a wide range, avoiding oscillation and shutdown, and can realize position-free control of the wind turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 The present invention is a flow chart of the wind turbine current control method.

[0062] Figure 2 It is a structural schematic diagram of the present invention.

[0063] In the figure: 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 DESCRIPTION

[0064] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0065] The present invention eliminates the problem of difficulty in detecting wind turbine parameters using instruments or additional test hardware, can identify resistance and inductance parameters before the wind turbine is operated, and has good robustness when the speed changes over a wide range, avoiding oscillation or even freezing, and improving the dynamic performance and steady-state accuracy of position-free control.

[0066] like Figure 1As shown, the position and speed estimation method provided by the embodiment of the present invention includes the following steps:

[0067] S101: Identify wind turbine parameters using a high-frequency signal injection method;

[0068] The resistance and inductance are identified respectively, and the specific methods are as follows:

[0069] Resistance identification: Usually the volt-ampere method is used for identification. Phase A is connected to the positive electrode, and phases B and C are connected to the negative electrode. A DC voltage is continuously applied. The resistance value is calculated directly based on the applied voltage and the sampled current using Ohm's law. The specific calculation expression is:

[0070]

[0071] Among them, U1 and U2 are the voltage amplitudes at the previous and next moments, and I1 and I2 are the current amplitudes at the previous and next moments.

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

[0073]

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

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

[0076] Among them, the stator current component i α and i β , stator voltage component u α and u β They are all components in the 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] Get the phase current of each phase in the current control cycle. Specifically, you can get the phase current of any two phases, such as i a and i b , then based on i a +i b +i c =0Calculate i c , for phase current i a 、i b 、ic Transform to obtain the stator current component i in the two-phase stationary coordinate system α and i β , and its calculation formula is:

[0079]

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

[0081] Get 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] For the above three-phase phase voltage U a , U b , U c Transform to obtain the stator voltage component U in the two-phase stationary coordinate system α and U β , the specific expression is:

[0085]

[0086] S103: deriving a dq-axis estimation coordinate system equation using coordinate transformation;

[0087] Specifically, the process of obtaining the stator voltage component of the current control cycle includes:

[0088]

[0089] make L d =L q =L,

[0090]

[0091] Finally, the dq-axis estimated coordinate system equation is simplified:

[0092]

[0093] in: and is the estimated value of the sub-current in the rotating coordinate system, and is the estimated value of the stator voltage in the rotating coordinate system, R and L are the stator resistance and the AC-axis inductance, is the estimated value of electrical angular velocity, is the electrical angle error component.

[0094] S104: using the dq axis estimation coordinate system equation to calculate and obtain an expression containing angle error information;

[0095] The specific calculation expression is:

[0096]

[0097] S105: performing a mathematical transformation on the angle error information expression to obtain a new angle and speed estimator, and implementing a new control method based on the estimator;

[0098] The angle error information expression is mathematically transformed, and the specific expression is:

[0099]

[0100] The specific calculation formula of the angle and speed estimator is:

[0101]

[0102] in represents the estimated value of electrical angular velocity, is the electrical angle error component, k p and k i is a parameter.

[0103] S106: Perform error compensation on the current loop to eliminate position estimation error disturbance and improve the stability and dynamic performance of the system. The specific steps are as follows:

[0104] In the d-axis current loop compensation error disturbance term The specific expression is:

[0105]

[0106] Finally, we get:

[0107]

[0108] Similarly, in the q-axis current loop compensation error interference term The specific expression is:

[0109]

[0110] Finally, we get:

[0111]

[0112] like Figure 2As shown, the wind turbine current control device provided by the embodiment of the present 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 rotation speed estimation module 5.

[0113] The voltage and current acquisition module 1 obtains the three-phase stator current and the three-phase stator voltage, and inputs the obtained signal into the filtering module 2, the signal amplification module 3, the analog-to-digital conversion module 4, and then into the angle and speed estimation module 5. The DSP or MCU runs a new position and speed estimation algorithm to estimate the position and speed of the wind turbine. The estimated position and speed are compared with the real position and speed of the wind turbine acquired by the encoder. The results are basically consistent, and the system has excellent dynamic performance and steady-state accuracy when the speed changes over a wide range, which proves that the estimation method proposed in the present invention is accurate.

[0114] 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 in the protection scope of the present invention.

Claims

1. A wind turbine current control method based on disturbance compensation and parameter identification, characterized in that: The steps include: S101: Identify the resistance and inductance parameters of wind turbines using a high-frequency signal injection method; S102: Obtaining a stator current component and a stator voltage component of the wind turbine generator set; S103: performing coordinate transformation on the stator current component and the stator voltage component to obtain a dq-axis estimation coordinate system equation; S104: using the dq axis estimation coordinate system equation to calculate and obtain an expression containing angle error information; S105: mathematically transforming the angle error information expression to obtain a novel angle and speed estimator, and implementing a novel position-free control method based on the estimator; S106: Perform error compensation on the d-axis and q-axis current loops to eliminate position estimation error disturbance.

2. A wind turbine current control method based on disturbance compensation and parameter identification according to claim 1, characterized in that: In S101, the resistance and inductance are identified respectively: Resistance identification: Use the volt-ampere method to identify, connect phase A of the fan to the positive pole, phases B and C to the negative pole, apply a DC voltage, and directly calculate the resistance value using Ohm's law based on the applied voltage and sampled current; The specific calculation expression is: Among them, U1 and U2 are the voltage amplitudes at the previous and next moments, and I1 and I2 are the current amplitudes at the previous and next moments; Inductance identification: Inject a high-frequency voltage vector into the dq axis and calculate the inductance based on the mathematical model and current response. The specific calculation expression is: Among them, U inv is the high frequency voltage vector amplitude, I dh is the amplitude of the high-frequency current component, ω h is the injected high frequency voltage vector frequency.

3. A wind turbine current control method based on disturbance compensation and parameter identification according to claim 2, characterized in that: The S102 is specifically: Get the stator current component i of the wind turbine a 、i b 、i c and the stator voltage component u a 、u b 、u c And the current component i in the rotating coordinate system is estimated by coordinate transformation d 、i q and voltage component u d 、u q ; Among them, the stator current component i α and i β , stator voltage component u α and u β They are all components in the two-phase stationary coordinate system.

4. A wind turbine 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 cycle includes: Get the phase current of each phase in the current control cycle, and get the phase current i of any two phases a and i b , then based on i a +i b +i c =0Calculate i c , for phase current i a 、i b 、i c Transform to obtain the stator current component i in the two-phase stationary coordinate system α and i β , and its calculation formula is: The process of obtaining the stator voltage component of the current control cycle includes: Get the DC bus voltage U of the current control cycle dc and the current switch state S j (j = a, b, c); Reconstructing three-phase phase voltages based on the DC bus voltage and the current switch state; For the above three-phase phase voltage U a , U b , U c Transform to obtain the stator voltage component U in the two-phase stationary coordinate system α and U β , the specific expression is:

5. A wind turbine current control method based on disturbance compensation and parameter identification according to claim 4, characterized in that: The S103 is specifically: The coordinate system equation of the dq axis estimation is obtained by coordinate transformation: in and is the current component in the dq estimation coordinate system, R and L are the stator resistance and the AC and DC axis inductance, and is the voltage component in the dq estimation coordinate system, ψ f is the permanent magnet flux, is the estimated value of electrical angular velocity, is the electrical angle error component.

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

7. A wind turbine current control method based on disturbance compensation and parameter identification according to claim 6, characterized in that: The S105 is specifically as follows: The specific expression of mathematical transformation is: The specific expressions of the angle and speed estimator are: Among them, ψ f is the magnetic flux, ω is the electrical angular velocity, is the electrical angle error component, The estimated electrical angle, is the estimated value of electrical angular velocity, k p and k i is a design parameter.

8. A wind turbine current control method based on disturbance compensation and parameter identification according to claim 7, characterized in that: The S106 is specifically as follows: 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 interference term The specific expression is: Finally, we get:

9. A high-precision wind turbine current control device based on position estimation error compensation and parameter identification for implementing the method according to any one of claims 1 to 8, 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 rotation 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 passed through a filtering module (2), a signal amplification module (3), an analog-to-digital conversion module (4) and a rotation speed estimation module (5); the rotation speed estimation module (5) estimates the angle and angular velocity.

10. A high-precision wind turbine current control device based on position estimation error compensation and parameter identification according to claim 9, characterized in that: The current and voltage acquisition module (1) is based on the Hall effect and is installed on the three phase lines a, b and c of the fan.

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