Speed sensorless control method suitable for wind power permanent magnet synchronous generator

Abstract

A speed sensorless control method suitable for a wind power permanent magnet synchronous generator belongs to the technical field of speed sensorless, and comprises the following steps: S1, constructing a single synchronous coordinate system phase locking model, and performing phase locking on power grid voltage through a d-axis component; s2, constructing a dq-axis oriented rotor position orientation regulator, and dynamically adjusting a phase angle under a load condition through a phase angle of no-load phase locking; and S3, constructing a megawatt permanent magnet synchronous wind generator speed sensorless vector control model. Real-time phase locking of generator stator voltage is realized through a software phase-locked loop model, a stator voltage vector angle is used as feedforward input, and a position orientation regulator of a rotor d-axis or q-axis is established according to a model reference adaptive principle, so that accurate orientation of a vector control coordinate system is realized; the speed sensorless control method not only has good torque and rotating speed dynamic and static following capability, but also is simple in engineering application and strong in system robustness.

Description

Technical Field

[0001] The present invention belongs to the technical field of speed sensorless technology, and in particular relates to a speed sensorless control method applicable to a wind power permanent magnet synchronous generator. Background Art

[0002] Prior art CN111934589B discloses a speed sensorless control method for a traction motor based on an improved Q-type phase-locked loop. The stability of the system is affected during speed changes, which in turn leads to instability of the phase-locked link, affecting the phase lock.

[0003] Prior art CN109412489B discloses a speed sensorless control strategy for a linear traction motor based on a phase-locked loop, which estimates the speed by phase-locking the back electromotive force amplitude. However, different working conditions of the motor may cause instability of the phase-locked link and thus interference with the estimated speed. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes: a speed sensorless control method applicable to a wind power permanent magnet synchronous generator, comprising the following steps:

[0005] S1. Construct a single synchronous coordinate system phase-locked model to phase-lock the grid voltage through the d-axis component;

[0006] S2, construct a dq-axis oriented rotor position directional regulator, and dynamically adjust the phase angle under load through the phase angle of no-load phase locking;

[0007] S3. Construct a speed sensorless vector control model for a megawatt-class permanent magnet synchronous wind turbine.

[0008] Furthermore, in step S1, the single synchronous coordinate system software phase-locked method SSRF-SPLL is selected for modeling, u A 、u B 、u C is the three-phase voltage of the motor stator detected by the sensor, T 3 / 2s represents the transformation from the three-phase stationary coordinate system to the two-phase stationary αβ coordinate system, T 2s / 2r represents the transformation from the αβ coordinate system to the synchronously rotating d'q' coordinate system, u sd’ 、u sq’ is the stator voltage component in the d'q' coordinate system, for u s Synchronous rotation angular velocity, stator voltage u s Oriented on the q' axis.

[0009] Furthermore, in step S2, the PMSG vector diagram is expressed based on the generator convention: the q-axis in the dq coordinate system is oriented with the rotor induced electromotive force e0, and the q'-axis in the d'q' coordinate system is oriented with the stator voltage vector u s Orientation, αβ axis is a two-phase stationary coordinate system, u s Vector orientation angle The value is detected in real time by a phase-locked loop method.

[0010] Furthermore, in step S2, two integration links are provided in the SSRF-SPLL model.

[0011] Further, in step S2, PMSG is detected by SSRF-SPLL. and After the value is obtained, the δ value is determined in real time through model reference adaptive control.

[0012] Furthermore, when the PMSG is operating in steady-state power generation, it is converted into:

[0013]

[0014] In the above formula, is the reference value of d-axis voltage, is the reference value of d-axis current, is the reference value of q-axis voltage, is the current reference of the q axis, for u s Synchronous rotation angular velocity, ψ f is the d-axis component of the stator induced electromotive force.

[0015] Furthermore, according to the detected The value is used to construct a rotor position orientation regulator based on the d-axis orientation or the q-axis orientation, thereby obtaining the δ value and the orientation angle of the dq coordinate system.

[0016] Among them, u d 、u q is an adjustable quantity, and u d 、u q Real-time tracking value, thereby achieving δ and Model reference adaptive control.

[0017] Furthermore, in step S3, the phase-locked loop model is converted into a linearized model. When the phase-locked loop can respond in real time and the phase is locked accurately, the stator voltage vector angle is approximately equal to the estimated angle, that is, When , we can have: The linearized model of the phase-locked loop system can be obtained. The open-loop transfer function and closed-loop transfer function of the linearized model system are:

[0018]

[0019] The damping coefficient and natural frequency of the second-order system are:

[0020]

[0021] From the above formula, we can get the ξ and ω of the second-order system transfer function. n They are all related to the stator voltage amplitude, but the stator voltage is not a constant. During the rapid change of speed, the stator voltage amplitude will change greatly, so the stability of the phase-locked loop system under different working conditions must be considered. In this case, the relevant regulator parameters are adjusted by drawing the system root trajectory, step response and Bode diagram.

[0022] Furthermore, at the lowest and highest speeds of the generator, the peak value of the stator phase voltage of the megawatt-class generator is between 100VAC and 600VAC. The middle value of 300V is taken as the reference point to design the regulator parameters. At the same time, under this parameter, u s At the minimum and maximum values, the system's dynamic response process is determined to determine the phase-locked loop regulator parameters.

[0023] The beneficial effects of the present invention are as follows: the present invention studies the speed sensorless control method of a permanent magnet synchronous wind generator, and for the specific operating conditions of the permanent magnet synchronous wind generator in a direct drive system, proposes a speed sensorless control method that improves the phase-locked loop regulation through a model reference adaptive method, and the method achieves simple and accurate identification.

[0024] The invention discloses a method for realizing a speed sensorless megawatt-class permanent magnet synchronous wind turbine suitable for engineering applications, namely, a software phase-locked loop model is used to phase-lock the stator voltage of the generator in real time, and the stator voltage vector angle is used as a feedforward input. A position orientation regulator of the rotor d-axis or q-axis is established according to the model reference adaptive principle, thereby realizing accurate orientation of a vector control coordinate system. The proposed speed sensorless control method not only has good dynamic and static following capabilities of torque and speed, but also is relatively simple in engineering application and has strong system robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Block diagram of speed sensorless vector control of megawatt-class permanent magnet synchronous wind turbine generator;

[0026] Figure 2 Space vector diagram of permanent magnet synchronous wind turbine;

[0027] Figure 3 PMSG power generation operation vector diagram;

[0028] Figure 4 SSRF-SPLL control structure schematic diagram;

[0029] Figure 5 The control block diagram of the rotor position directional regulator based on d-axis orientation;

[0030] Figure 6 The control block diagram of the rotor position directional regulator based on q-axis orientation;

[0031] Figure 7 Linearization model diagram of phase-locked loop; DETAILED DESCRIPTION

[0032] Example 1

[0033] In order to make the technical means and objectives of the present invention easy to understand, the present invention is further described below in combination with specific implementation methods. A speed sensorless control method applicable to a wind power permanent magnet synchronous generator comprises the following steps:

[0034] S1. Construct a single synchronous coordinate system phase-locked model to phase-lock the grid voltage through the d-axis component;

[0035] S2, construct a dq-axis oriented rotor position directional regulator, and dynamically adjust the phase angle under load through the phase angle of no-load phase locking;

[0036] S3. Construct a speed sensorless vector control model for a megawatt-class permanent magnet synchronous wind turbine.

[0037] In step S1, the single synchronous coordinate system software phase-locked method SSRF-SPLL is selected for modeling. A 、u B 、u C is the three-phase voltage of the motor stator detected by the sensor, T 3 / 2s represents the transformation from the three-phase stationary coordinate system to the two-phase stationary αβ coordinate system, T 2s / 2r represents the transformation from the αβ coordinate system to the synchronously rotating d'q' coordinate system, u sd’ 、u sq’ is the stator voltage component in the d'q' coordinate system, for u s Synchronous rotation angular velocity, stator voltage u s Oriented on the q' axis.

[0038] Among them, in the step S2, the PMSG vector diagram is expressed based on the generator convention: the q-axis in the dq coordinate system is oriented with the rotor induced electromotive force e_0, the q'-axis in the d'q' coordinate system is oriented with the stator voltage vector u_s, the αβ axes are two-phase stationary coordinate systems, and the u_s vector orientation angle θ^ value is detected in real time by the phase-locked loop method.

[0039] Wherein, in step S2, two integration links are set in the SSRF-SPLL model.

[0040] Wherein, in step S2, PMSG is detected by SSRF-SPLL and After the value is obtained, the δ value is determined in real time through model reference adaptive control.

[0041] Among them, when PMSG is operating in steady-state power generation, it is converted into:

[0042]

[0043] In the above formula, is the reference value of d-axis voltage, is the reference value of d-axis current, is the reference value of q-axis voltage, is the current reference of the q axis, for u s Synchronous rotation angular velocity, ψ f is the d-axis component of the stator induced electromotive force.

[0044] Among them, according to the detection The value is used to construct a rotor position orientation regulator based on the d-axis orientation or the q-axis orientation, thereby obtaining the δ value and the orientation angle of the dq coordinate system.

[0045] Among them, u d 、u q is an adjustable quantity, and u d 、u q Real-time tracking value, thereby achieving δ and Model reference adaptive control.

[0046] Among them, in step S3, the phase-locked loop model is converted into a linearized model. When the phase-locked loop can respond in real time and the phase is locked accurately, the stator voltage vector angle is approximately equal to the estimated angle, that is, When , we can have: The linearized model of the phase-locked loop system can be obtained. The open-loop transfer function and closed-loop transfer function of the linearized model system are:

[0047]

[0048] The damping coefficient and natural frequency of the second-order system are:

[0049]

[0050] From the above formula, we can get the ξ and ω of the second-order system transfer function. n They are all related to the stator voltage amplitude, but the stator voltage is not a constant. During the rapid change of speed, the stator voltage amplitude will change greatly, so the stability of the phase-locked loop system under different working conditions must be considered. In this case, the relevant regulator parameters are adjusted by drawing the system root trajectory, step response and Bode diagram.

[0051] Among them, at the lowest and highest speeds of the generator, the peak value of the stator phase voltage of the megawatt-class generator is between 100VAC and 600VAC. The middle value of 300V is taken as the reference point to design the regulator parameters. At the same time, under this parameter, u s At the minimum and maximum values, the system's dynamic response process is determined to determine the phase-locked loop regulator parameters.

[0052] Example 2

[0053] like Figure 1 As shown in the figure, the speed sensorless control module of the vector control block diagram of the megawatt-class permanent magnet synchronous wind turbine is improved, and the phase angle is locked through the model reference adaptive method. The proposed method realizes the key technical requirement of speed sensorless control of the direct drive system.

[0054] When PMSG is running at no-load, Figure 1 It can be seen from the control block diagram that the rotor induced electromotive force is equivalent to the stator voltage. Therefore, if the stator voltage is phase-locked through the software phase-locked loop model to determine the stator voltage vector position during no-load operation, the rotor magnetic field position during no-load operation can be determined in real time, thereby establishing a vector control coordinate system during no-load operation.

[0055] When PMSG is running with load, according to Figure 2 From the vector relationship, it can be seen that there is a phase difference of angle δ between the stator induced electromotive force and the d-axis. At this moment, the phase-locked stator voltage vector angle can be used as the feedforward input. Then, according to the generator model and model reference adaptive (MARS) principle, a directional regulator of the rotor position can be established to obtain information related to the angle δ and realize the orientation of the rotor magnetic field position during load operation.

[0056] In order to illustrate the proposed speed sensorless working principle and facilitate theoretical analysis, the PMSG vector diagram based on the generator convention is presented again here, as follows: Figure 3In the figure: the q-axis in the dq coordinate system is oriented with the rotor induced electromotive force e0, and the q'-axis in the d'q' coordinate system is oriented with the stator voltage vector u s Orientation, αβ axis is the two-phase stationary coordinate system.

[0057] like Figure 4 As shown, u s Vector orientation angle The value can be detected in real time by the phase-locked loop method. The phase-locked loop method has been systematically summarized and analyzed. It can be divided into open-loop phase-locked and closed-loop phase-locked. The commonly used open-loop phase-locked methods are: phase-locked method based on low filter (LPF), phase-locked method based on space vector filter (SVF), phase-locked method based on extended Kalman filter (EKF), phase-locked method based on weighted least squares estimation (WLSE), etc.; the closed-loop phase-locked methods are generally: hardware phase-locked, software phase-locked method based on adaptive principle, single synchronous coordinate system software phase-locked method (SingleSynchronous Reference Frame Software phase locked loop, referred to as SSRF-SPLL), decoupled software phase-locked method of dual synchronous coordinate system (Decoupled Double Synchronous Reference Frame SPLL, referred to as DDSRF-SPLL), etc. The instability of wind speed in the direct drive system requires consideration of the real-time and rapid detection of the stator voltage phase. At the same time, there are problems such as the three-phase imbalance of the stator voltage caused by the rapid fluctuation of the motor speed when the wind speed changes rapidly. The detection of the stator voltage phase requires a closed-loop phase-locked method.

[0058] According to the closed-loop phase-locked method mentioned above, considering that the stator voltage will not drop or be seriously unbalanced, and that engineering applications require good steady-state and dynamic following performance, step S1 includes the following: Selecting the SSRF-SPLL method for modeling, the basic principle of which is as follows: Figure 4 As shown in the figure, u A 、u B 、u C is the three-phase voltage of the motor stator detected by the sensor, T 3 / 2s represents the transformation from the three-phase stationary coordinate system to the two-phase stationary αβ coordinate system, T 2s / 2r represents the transformation from the αβ coordinate system to the synchronously rotating d'q' coordinate system, u sd’ 、u sq’ is the stator voltage component in the d'q' coordinate system, for u s Synchronous rotation angular velocity, Figure 4 The stator voltage u s Oriented on the q' axis.

[0059] Figure 4 Since there are two integral links in the model, even when the machine-side converter is working and high-order harmonics are superimposed on the motor stator voltage, the high-frequency components can be strongly suppressed by appropriately reducing the frequency band of the system, thereby making the SSRF-SPLL model more robust.

[0060] PMSG was detected by SSRF-SPLL and After the value is obtained, the δ value can be determined in real time through model reference adaptive control. When the PMSG is operating in steady-state power generation, it can be converted into:

[0061]

[0062] In the above formula, is the reference value of d-axis voltage, is the reference value of d-axis current, is the reference value of q-axis voltage, is the current reference of the q axis, for u s Synchronous rotation angular velocity, ψ f is the d-axis component of the stator induced electromotive force. The rotor position orientation regulator based on d-axis orientation or q-axis orientation can be constructed by using the value, respectively. Figure 5 , Figure 6 As shown, the δ value and the orientation angle of the dq coordinate system can be obtained

[0063] Figure 5 , 6 in, u d 、u q is an adjustable quantity, and u d 、u q Real-time tracking value, thereby achieving δ and Model reference adaptive control.

[0064] The core of the PMSG speed sensorless control method discussed in this patent is the phase-locked loop model. In order to enable the proposed speed sensorless control method to be reliably applied to the megawatt-level PMSG vector control system in engineering, the early modeling of the phase-locked loop and the design of the phase-locked loop sub-control system are particularly critical. For this reason, this section conducts an approximate analysis of the phase-locked loop model and discusses its control system design method.

[0065] Depend on Figure 4It can be seen that the structure of the phase-locked loop model is very simple, and it is a linearized model. When the phase-locked loop can respond in real time and the phase is locked accurately, the stator voltage vector angle is approximately equal to the estimated angle, that is, When , we can have: Therefore, the linearization model of the phase-locked loop system is as follows: Figure 7 shown.

[0066] Depend on Figure 7 The open-loop transfer function and closed-loop transfer function of the system are:

[0067]

[0068] The damping coefficient and natural frequency of the second-order system are:

[0069]

[0070] From the above formula, we can get the ξ and ω of the second-order system transfer function. n They are all related to the stator voltage amplitude, but the stator voltage is not a constant value. During the rapid change of speed, the stator voltage amplitude will change greatly, so the stability of the phase-locked loop system under different working conditions must be considered. In this case, the relevant regulator parameters can be adjusted by drawing the system root locus, step response and Bode diagram.

[0071] At the lowest and highest speeds of the generator, the peak value of the stator phase voltage of the megawatt-class generator is generally between 100VAC and 600VAC. In general, the middle value of 300V is taken as the reference point to design the regulator parameters. At the same time, under this parameter, u s At the minimum and maximum values, the system's dynamic response process is determined to determine the phase-locked loop regulator parameters.

[0072] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A speed sensorless control method for a wind power permanent magnet synchronous generator, characterized in that: The steps include: S1. Construct a single synchronous coordinate system phase-locked model to phase-lock the grid voltage through the d-axis component; S2, construct a dq-axis oriented rotor position directional regulator, and dynamically adjust the phase angle under load through the phase angle of no-load phase locking; S3. Construct a speed sensorless vector control model for a megawatt-class permanent magnet synchronous wind turbine.

2. The speed sensorless control method for a wind power permanent magnet synchronous generator according to claim 1, characterized in that: In step S1, the single synchronous coordinate system software phase-locked method SSRF-SPLL is selected for modeling. A 、u B 、u C is the three-phase voltage of the motor stator detected by the sensor, T 3 / 2s represents the transformation from the three-phase stationary coordinate system to the two-phase stationary αβ coordinate system, T 2s / 2r represents the transformation from the αβ coordinate system to the synchronously rotating d'q' coordinate system, u sd’ 、u sq’ is the stator voltage component in the d'q' coordinate system, for u s Synchronous rotation angular velocity, stator voltage u s Oriented on the q' axis.

3. The speed sensorless control method for a wind power permanent magnet synchronous generator as claimed in claim 2, characterized in that: In the step S2, the PMSG vector diagram is expressed based on the generator convention: the q-axis in the dq coordinate system is oriented with the rotor induced electromotive force e_0, the q'-axis in the d'q' coordinate system is oriented with the stator voltage vector u_s, the αβ-axis is a two-phase stationary coordinate system, and the u_s vector orientation angle θ^ value is detected in real time by a phase-locked loop method.

4. The speed sensorless control method for a wind power permanent magnet synchronous generator as claimed in claim 3, characterized in that: In step S2, two integration links are set in the SSRF-SPLL model.

5. The speed sensorless control method for a wind power permanent magnet synchronous generator as claimed in claim 4, characterized in that: In step S2, PMSG is detected by SSRF-SPLL. and After the value is obtained, the δ value is determined in real time through model reference adaptive control.

6. The speed sensorless control method for a wind power permanent magnet synchronous generator as claimed in claim 5, characterized in that: When PMSG is operating in steady-state power generation, it is converted into: In the above formula, is the reference value of d-axis voltage, is the reference value of d-axis current, is the reference value of q-axis voltage, is the current reference of the q axis, for u s Synchronous rotation angular velocity, ψ f is the d-axis component of the stator induced electromotive force.

7. The speed sensorless control method for a wind power permanent magnet synchronous generator as claimed in claim 6, characterized in that: According to the detected The value is used to construct a rotor position orientation regulator based on the d-axis orientation or the q-axis orientation, thereby obtaining the δ value and the orientation angle of the dq coordinate system. Among them, u d 、u q is an adjustable quantity, and u d 、u q Real-time tracking value, thereby achieving δ and Model reference adaptive control.

8. The speed sensorless control method for a wind power permanent magnet synchronous generator as claimed in claim 7, characterized in that: In step S3, the phase-locked loop model is converted into a linearized model. When the phase-locked loop can respond in real time and the phase is locked accurately, the stator voltage vector angle is approximately equal to the estimated angle, that is, When , we can have: The linearized model of the phase-locked loop system can be obtained. The open-loop transfer function and closed-loop transfer function of the linearized model system are: The damping coefficient and natural frequency of the second-order system are: From the above formula, we can get the ξ and ω of the second-order system transfer function. n They are all related to the stator voltage amplitude, but the stator voltage is not a constant. During the rapid change of speed, the stator voltage amplitude will change greatly, so the stability of the phase-locked loop system under different working conditions must be considered. In this case, the relevant regulator parameters are adjusted by drawing the system root trajectory, step response and Bode diagram.

9. The speed sensorless control method for a wind power permanent magnet synchronous generator as claimed in claim 8, characterized in that: At the lowest and highest speeds of the generator, the peak value of the stator phase voltage of the megawatt-class generator is between 100VAC and 600VAC. The middle value of 300V is taken as the reference point to design the regulator parameters. At the same time, under this parameter, u s At the minimum and maximum values, the system's dynamic response process is determined to determine the phase-locked loop regulator parameters.

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