A Machine-Side Hybrid Control Method for a Permanent Magnet Synchronous Offshore Wind Power Generation System

Abstract

The invention discloses a machine-side hybrid control method for a permanent magnet synchronous offshore wind power generation system, which mainly includes a permanent magnet synchronous wind turbine, a permanent magnet synchronous wind turbine vector control system, a controller group and an SVPWM module; the controller group includes a switcher, a sliding mode controller and an active disturbance rejection controller. The control method is as follows: S1: Construct the permanent magnet synchronous wind turbine vector control system with double closed-loop control of a speed loop and a current loop; S2: Construct the mathematical model of the permanent magnet synchronous wind turbine; Define the state variables of the permanent magnet synchronous wind turbine and construct the system state equation; S3: Design a switcher; S4: Construct the controller group; S5: Apply the controller group to the speed loop of the permanent magnet synchronous wind turbine vector control system, and control the current loop of the permanent magnet synchronous wind turbine vector control system through a PI controller. It can effectively reduce the strong interference of the harsh working environment offshore on the permanent magnet synchronous wind turbine.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet synchronous wind generator control, and particularly relates to a machine-side hybrid control method for a permanent magnet synchronous offshore wind power generation system. Background Art

[0002] The environmental problems brought about by the use of fossil energy are becoming increasingly serious, which promotes the development and use of new energy. China is rich in wind resources. As a renewable clean energy, wind energy is an effective way to replace traditional energy. With the rapid development of permanent magnet materials and power electronics technology, the performance of permanent magnet synchronous wind generators (PMSGs) has also been greatly improved. Permanent magnet synchronous wind generators have excellent excitation performance, and have the advantages of small volume, light weight, high power, etc. At present, they are widely used in fields such as wind generators and aerospace high-speed generators.

[0003] The control system of a permanent magnet synchronous wind power generation set generally adopts a vector control strategy. The basic idea of vector control is to decouple the magnetic flux, voltage and current of a permanent magnet synchronous wind generator through coordinate transformation to obtain the corresponding torque and magnetic field components, which are respectively controlled by current. This is similar to a DC motor. The current of a permanent magnet synchronous wind generator and the magnetic flux generated by the rare earth permanent magnet on the rotor do not interfere with each other, which is convenient for control, the torque is constant, and the pulsation is relatively small, and good dynamic performance and a wide speed regulation range can be obtained. Since a permanent magnet synchronous wind generator is a complex object with multiple variables, strong coupling and nonlinearity, the harsh working environment at sea has a strong interference effect on the permanent magnet synchronous wind generator, which will cause a significant decline in the control effect. Summary of the Invention

[0004] The present invention provides a machine-side hybrid control method for a permanent magnet synchronous offshore wind power generation system to solve one or more of the problems raised in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solution: A machine-side hybrid control method for a permanent magnet synchronous offshore wind power generation system, characterized in that it includes: a permanent magnet synchronous offshore wind power generation system, the permanent magnet synchronous offshore wind power generation system includes a permanent magnet synchronous wind generator, a permanent magnet synchronous wind generator vector control system, a controller group and an SVPWM module; the controller group includes a switcher, a sliding mode controller, and an active disturbance rejection controller;

[0006] Steps for controlling the permanent magnet synchronous offshore wind power generation system:

[0007] S1: Construct the vector control system of the permanent magnet synchronous wind generator with double closed-loop control of a speed loop and a current loop;

[0008] S2: Construct the mathematical model of the permanent magnet synchronous wind generator;

[0009] Define the state variables of the permanent magnet synchronous wind generator and construct the system state equation;

[0010] S3: Design a switch;

[0011] S4: Construct the controller group:

[0012] S41 Construct the sliding mode controller;

[0013] S42 Construct the active disturbance rejection controller;

[0014] S43 The switch controls the switches of the sliding mode controller and the active disturbance rejection controller;

[0015] S5: Apply the controller group to the speed loop of the permanent magnet synchronous wind generator vector control system, control the current loop of the permanent magnet synchronous wind generator vector control system through a PI controller, and then control the permanent magnet synchronous wind generator vector control system.

[0016] Preferably, the step S2 includes:

[0017] The mathematical model of the permanent magnet synchronous wind generator is:

[0018] where i q is the q-axis current; u q is the q-axis voltage; L s is the stator inductance; R is the stator resistance; ω m is the mechanical angular velocity of the motor; J is the moment of inertia; p n is the number of pole pairs; ψ f is the rotor permanent magnet flux linkage; T L is the load torque.

[0019] Define the state variables of the permanent magnet synchronous wind generator vector control system: x1 = ω ref -ω m 、 where ω ref is the given speed, ω m is the actual speed.

[0020] Let Then the system state equation is:

[0021]

[0022] Preferably, test the control effects of the sliding mode controller and the active disturbance rejection controller on the permanent magnet synchronous wind generator under different interference signals, and find out the reference value R that can distinguish the control effects;

[0023] The switching equation of the switch is designed as follows:

[0024] where y is the output of the switch, y1 is the output of the active disturbance rejection controller, y2 is the output of the sliding mode controller, and D is the disturbance term.

[0025] When the state of the permanent magnet synchronous wind turbine control system is known, and D > R or D < -R, the switch switches to the output of the active disturbance rejection controller;

[0026] When the state of the permanent magnet synchronous wind turbine control system is known, and -R ≤ D ≤ R, the switch switches to the output of the sliding mode controller;

[0027] When the state of the permanent magnet synchronous wind turbine control system is unknown, R can be set to 0, and the switch switches to the output of the active disturbance rejection controller;

[0028] The state variable of the system is defined as the error between the reference speed and the actual speed of the generator. The unknown system state means that the actual speed of the generator cannot be measured, and the known system state means that the actual speed of the generator can be measured.

[0029] Preferably, after the controller group finishes the judgment, the d-axis and q-axis voltages of the permanent magnet synchronous wind turbine are decoupled, and the rectifier is controlled by SVPWM modulation, so as to control the permanent magnet synchronous wind turbine.

[0030] Preferably, the SVPWM module for modulating and controlling the rectifier includes the following steps:

[0031] 7.1. Judge the sector where the synthesized vector is located;

[0032] 7.2. Allocate the action time of the vector according to the sector;

[0033] 7.3. Calculate the switching point of the voltage space vector;

[0034] 7.4. PWM output. After calculating the switching points of each vector in each sampling period, compare them with a triangular carrier wave with a frequency of 10 kHz and an amplitude of 5×10 -5 to output a PWM wave to control the rectifier.

[0035] The technical solution of the present invention has the following advantages:

[0036] 1. The present invention designs a hybrid control method of sliding mode control and active disturbance rejection control. By using the function of the switch, when the system state is known, it can work in the state of the hybrid output of the two controllers according to the disturbance of the system. When the system state is unknown, it can switch to the output of the active disturbance rejection controller, which can better achieve the anti-disturbance effect. Description of the Drawings

[0037] Figure 1 It is a schematic flow chart of the control method of the present invention.

[0038] Figure 2 It is a schematic diagram of the principle of the permanent magnet synchronous wind power generation control system in the embodiment of the present invention.

[0039] Figure 3 It is a flow chart of the switch group in the embodiment of the present invention. Detailed Embodiments

[0040] The following further describes the present application with reference to the drawings. The specific embodiments described herein are only for explaining the related invention and not for limiting the invention.

[0041] Permanent magnet synchronous wind turbine, permanent magnet synchronous wind turbine vector control system, controller group and SVPWM module;

[0042] The controller group includes a switch, a sliding mode controller, and an active disturbance rejection controller.

[0043] Please refer to Figure 1 , and construct the following steps:

[0044] S1: Construct the permanent magnet synchronous wind turbine vector control system with double closed-loop control of speed loop and current loop;

[0045] S1-1: On the generator side of the permanent magnet synchronous wind turbine, use a speed encoder to collect the motor rotor speed ω and the rotor position signal θ. The given value of the generator rotor electrical angle is compared with the actual value ω e to construct the speed loop;

[0046] S1-2: Collect the three-phase alternating current i a , i b , i c of the permanent magnet synchronous wind turbine. After the three-phase current undergoes abc / αβ and αβ / dq transformations, the q-axis component i q and the d-axis component i d of the stator current are obtained. The d-axis current is controlled by . is compared with i d , is compared with i q to construct the current loop.

[0047] S2: Construct the mathematical model of the permanent magnet synchronous wind turbine;

[0048] Define the state variables of the permanent magnet synchronous wind turbine and construct the system state equation;

[0049] The mathematical model of the permanent magnet synchronous wind generator is as follows:

[0050] In the formula, i q is the q-axis current; u q is the q-axis voltage; L s is the stator inductance; R is the stator resistance; ω m is the mechanical angular velocity of the motor; J is the moment of inertia; p n is the number of pole pairs; ψ f is the rotor permanent magnet flux linkage; T L is the load torque.

[0051] Define the state variables of the vector control system of the permanent magnet synchronous wind generator: x1 = ω ref - ω m , In the formula, ω ref is the given rotational speed, and ω m is the actual rotational speed.

[0052] Let Then the system state equation is:

[0053]

[0054] S3: Design a switcher;

[0055] S4: Construct the controller group:

[0056] S41 Construct the sliding mode controller;

[0057] S42 Construct the active disturbance rejection controller;

[0058] S43 The switcher controls the switches of the sliding mode controller and the active disturbance rejection controller;

[0059] S5: Apply the controller group to the speed loop of the vector control system of the permanent magnet synchronous wind generator, control the current loop of the vector control system of the permanent magnet synchronous wind generator through a PI controller, and then control the vector control system of the permanent magnet synchronous wind generator.

[0060] The vector control system makes the d-axis component of the stator current be 0. The input of the speed controller is the error between the speed set value and the actual value. After passing through the speed controller, the actual value of the generator speed can track its set value, so as to achieve the purpose of speed regulation. After adding the current controller, the current can track the set value, improving the response speed and stability of the system.

[0061] Please see Figure 3, after testing the control effects of the sliding mode controller and the active disturbance rejection controller on the permanent magnet synchronous wind turbine under different disturbance signals, a reference value R that can distinguish the control effects is found;

[0062] The switching equation of the switch is designed as:

[0063] where y is the output of the switch, y1 is the output of the active disturbance rejection controller, y2 is the output of the sliding mode controller, and D is the disturbance term.

[0064] When adding disturbances, in order to simulate the disturbances suffered by the permanent magnet synchronous wind turbine in reality, a random disturbance signal obeying a normal distribution and a sine disturbance signal composed of a high frequency, high amplitude and a low frequency, low amplitude are applied to the speed loop of the system. In actual application, the actual speed can be measured by a sensor and then subtracted from the given speed to obtain an approximate disturbance D.

[0065] When the system state is known, when D > R or D < -R, the switch switches to the output of the active disturbance rejection controller;

[0066] When the system state is known, when -R ≤ D ≤ R, the switch switches to the output of the sliding mode controller;

[0067] When the system state is unknown, R can be set to 0, and the switch switches to the output of the active disturbance rejection controller.

[0068] Please see Figure 2 After the controller group finishes the judgment, the d-axis and q-axis voltages of the permanent magnet synchronous wind turbine are decoupled, and through the operation of the current PI regulator, the control voltage u of the system is obtained d and u q . After the dq / αβ transformation, the drive voltages u α and u β of the system are obtained. Through the SVPWM module, the PWM signal acts on the switching tubes of the rectifier to achieve the control of the output current of the generator.

[0069] The rectifier is controlled by SVPWM modulation, and then the permanent magnet synchronous wind turbine is controlled.

[0070] The SVPWM module modulating and controlling the rectifier includes the following steps:

[0071] 7.1. Judge the sector where the synthesized vector U out is located;

[0072] 7.2. Allocate the action time T1 and T2 of the vectors according to the sector;

[0073] 7.3. Calculate the switching point of the voltage space vector;

[0074] 7.4, PWM Output. After calculating the switching points of each vector within each sampling period, compare them with a triangular carrier wave of a certain frequency and amplitude, and output a PWM wave to control the rectifier.

[0075] In the above method for modulating and controlling a rectifier by an SVPWM module, three-phase voltage vectors can be superimposed into a space voltage vector. After determining the sector where the superimposed voltage vector is located, allocating the action time of the basic vectors, and calculating the switching points, its motion trajectory is approximated to a circle, so that the original three-phase voltages approach three-phase symmetric sine waves. Finally, the SVPWM module generates six PWM signals to control the turning on and off of the transistors of the rectifier, converting the three-phase alternating current generated by the generator into direct current.

[0076] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A machine-side hybrid control method for a permanent magnet synchronous offshore wind power generation system, characterized in that, Including: A permanent magnet synchronous offshore wind power generation system, which includes a permanent magnet synchronous wind generator, a permanent magnet synchronous wind generator vector control system, a controller group, and an SVPWM module; the controller group includes a switch, a sliding mode controller, and an active disturbance rejection controller; Steps for controlling the permanent magnet synchronous offshore wind power generation system: S1: Construct the permanent magnet synchronous wind generator vector control system with double closed-loop control of a speed loop and a current loop; S2: Construct the mathematical model of the permanent magnet synchronous wind generator; Define the state variables of the permanent magnet synchronous wind generator and construct the system state equation; S3: Design a switch; S4: Construct the controller group: S41 Construct the sliding mode controller; S42 Construct the active disturbance rejection controller; S43 The switch controls the switches of the sliding mode controller and the active disturbance rejection controller; S5: Apply the controller group to the speed loop of the permanent magnet synchronous wind generator vector control system, control the current loop of the permanent magnet synchronous wind generator vector control system through a PI controller, and then control the permanent magnet synchronous wind generator vector control system; Test the control effects of the sliding mode controller and the active disturbance rejection controller on the permanent magnet synchronous wind turbine under different disturbance signals, and find out the reference values that can distinguish the control effects ; The switching equation of the switch is designed as: , where is the output of the switcher, is the output of the active disturbance rejection controller, is the output of the sliding mode controller, is the disturbance term; When the state of the permanent magnet synchronous wind turbine control system is known, >R or < -R, the switcher switches to the output of the active disturbance rejection controller; When the state of the permanent magnet synchronous wind turbine control system is known, -R ≤ ≤ R, the switcher switches to the output of the sliding mode controller; When the state of the permanent magnet synchronous wind generator control system is unknown, it is possible to make and the switcher switches to the output of the active disturbance rejection controller; The state variable of the system is defined as the error between the reference speed and the actual speed of the generator. The unknown system state means that the actual speed of the generator cannot be measured, and the known system state means that the actual speed of the generator can be measured.

2. A machine-side hybrid control method for a permanent magnet synchronous offshore wind power generation system according to claim 1, characterized in that: The step S2 includes: The mathematical model of the permanent magnet synchronous wind turbine is as follows: ; Wherein, is the q-axis current; is the q-axis voltage; is the stator inductance; R is the stator resistance; is the mechanical angular velocity of the motor; is the moment of inertia; is the number of pole pairs; is the rotor permanent magnet flux linkage; is the load torque; Define the state variables of the vector control system of the permanent magnet synchronous wind generator: , ; where is the given speed, is the actual speed; Let , , then the system state equation is: 。 3. A machine-side hybrid control method for a permanent magnet synchronous offshore wind power generation system according to claim 2, characterized in that: After the controller group has completed the judgment, the , shaft voltage is decoupled, the rectifier is controlled by SVPWM modulation, and then the permanent magnet synchronous wind turbine is controlled.

4. A machine-side hybrid control method for a permanent magnet synchronous offshore wind power generation system according to claim 3, characterized in that, The SVPWM module modulation control rectifier includes the following steps: 7.

1. Judge the sector where the synthesized vector is located; 7.

2. Allocate the action time of the vector according to the sector; 7.

3. Calculate the voltage space vector switching point; 7.4, PWM Output: After calculating the switching points of each vector within each sampling period, compare them with a triangular carrier wave with a frequency of 10 kHz and an amplitude of to output a PWM wave to control the rectifier.

Images