Maximum power point tracking control method, device and storage medium for wind power generation system

Abstract

The present invention discloses a maximum power point tracking control method, device and storage medium for a wind power generation system. The maximum power point tracking control method for a wind power generation system includes the following contents: combining a three-phase commutation function of a brushless DC generator and utilizing a power converter switch switching technology, so that the wind power generation system can generate electricity at the maximum power point at any speed. The present invention has better accuracy and stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric transmission control equipment and mechanical lubrication and sealing technology, and specifically relates to a maximum power point tracking control method, device and storage medium for a wind power generation system, which can be used for military equipment such as artificial satellites and missiles, as well as high-reliability and stable control systems for flywheel energy storage, generators, and artificial heart pumps in the field of motor transmission. Background Art

[0002] In recent years, the world has advocated the application of new green energy. Therefore, the use of new energy sources such as wind power generation systems, which do not emit carbon dioxide, are inexhaustible, and are the purest energy, has become one of the most important topics in the world. The wind power generation system includes components such as DC brushless generators, three-phase bridge rectifiers, and power converters. The wind power generation system converts kinetic energy into electrical energy by driving the permanent magnet brushless generator. The three-phase AC voltage generated by the generator is rectified into DC power by a three-phase full-wave rectifier, and then converted into voltage output by a DC converter. The system DC converter uses a Boost converter. In the wind power generation system, the output power of the generator will affect the output power curve of the wind power generation system due to the relationship between wind speed. At different speeds, the generator will have different nonlinear characteristic curves, and each characteristic curve has an optimal working point, namely the maximum power point.

[0003] Traditionally, the output of wind power conversion is controlled by voltage regulation. Currently, many experts and scholars have proposed maximum power point tracking control methods for different new energy applications. Common methods include perturbation observation method, etc. These operation methods are often proposed and applied because they are easy to implement and low in cost. However, these operation methods are not robust. Therefore, when these operation methods reach the maximum power point stable state, the operation point is prone to disturbance oscillation near the maximum power point due to external interference. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a maximum power point tracking control method, device and storage medium for a wind power generation system.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] On the one hand, the present invention discloses a maximum power point tracking control method for a wind power generation system, comprising the following contents: combining a three-phase commutation function of a brushless DC generator and utilizing a power converter switch switching technology, so that the wind power generation system can generate electricity at the maximum power point at any speed, as shown in formula (1):

[0007]

[0008] Among them, P mis the equivalent conversion power of the brushless DC generator;

[0009] V m is the equivalent DC dynamic model of the DC brushless generator;

[0010] I m is the equivalent DC armature current of the DC brushless generator;

[0011] The sliding plane is defined as shown in formula (2):

[0012]

[0013] When the system is in sliding mode state, S=0;

[0014] The sliding mode plane equivalent control Ueq is shown in equations (3)-(5):

[0015]

[0016]

[0017]

[0018] Among them: f(x) and g(x) are nonlinear functions;

[0019] U m is the maximum equivalent control function;

[0020] V 0 is the control voltage;

[0021] i L It controls the current.

[0022] Based on the above technical solution, the following improvements can be made:

[0023] As a preferred solution, P m =P g , P g is the converter brushless DC generator power, obtained by the following;

[0024] The wind power generation system uses a three-phase DC brushless generator, and its dynamic equation is shown in equation (6);

[0025]

[0026] Among them, Rs is the coil resistance, L is the coil self-inductance, and M is the coil mutual inductance;

[0027] e a 、e b 、e c They represent the generator back EMF, i a、i b 、i c Respectively represent the phase current, v a 、v b 、v c Respectively represent the terminal voltage;

[0028] Since the air gap flux density of the DC generator is designed to be a trapezoidal wave, the converter DC brushless generator power P g It is expressed as shown in formula (10);

[0029]

[0030]

[0031]

[0032] P g =e a i a +e b i b +e c i c ; (10)

[0033] Where: w e is a function of time;

[0034] K g and λ are coefficients;

[0035] t is time;

[0036] The three-phase commutation functions Sa(t), Sb(t), and Sc(t) of the brushless DC generator are shown in equations (11) to (13):

[0037]

[0038]

[0039]

[0040] Where u(t) is expressed as a unit step function and n is an integer;

[0041] Equivalent DC armature current i of brushless DC generator eq (t) as shown in formula (14);

[0042]

[0043] Equivalent DC potential e of brushless DC generator eq (t) and terminal voltage V eq (t) are respectively expressed as shown in equations (15) and (16);

[0044]

[0045]

[0046] The equivalent DC internal potential e of the DC brushless generator can be obtained by the above formula eq Its conversion power Pg is expressed as shown in equations (17) and (18);

[0047] e eq =K g w e λ; (17)

[0048] P g =K g w e λi eq (18)

[0049] As a preferred solution, I m =i eq .

[0050] As a preferred solution, V m =V eq , V eq Through formula (19), we get:

[0051]

[0052] On the other hand, the present invention also discloses a maximum power point tracking control device for a wind power generation system, which uses any of the above-mentioned maximum power point tracking control methods for a wind power generation system to control the wind power generation system to maintain maximum power point power generation at different rotation speeds.

[0053] On the other hand, the present invention further discloses a storage medium, wherein one or more programs include instructions, and the instructions are suitable for being loaded by a memory and executing any of the above-mentioned maximum power point tracking control methods for a wind power generation system.

[0054] The wind power generation system of the present invention adopts a three-phase DC brushless generator. Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) Since the generator of a wind power generation system has a nonlinear power-to-voltage characteristic and the output result of the generator power-voltage characteristic is affected by the wind speed, in order to enable the wind power generation system to continuously maintain the maximum power point at different speeds for power generation to improve power generation efficiency, the present invention proposes the application of improved sliding mode control to the maximum power point tracking of the wind power generation system.

[0056] (2) The present invention can effectively solve the shortcomings of poor robustness of traditional maximum power point tracking methods, perturbation observation method and incremental conductance method, and has better accuracy and stability.

[0057] (3) The present invention can effectively prevent the control input value from being in a saturated state for a long time, or switching between two saturated values ​​at a high speed, which may affect the life of the switching switch in the controller or cause high-frequency switching noise.

[0058] (4) The overall efficiency of the present invention is significantly improved in stability compared to traditional sliding mode control, and the response speed is also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0060] Figure 1 A flow chart of a maximum power point tracking control method for a wind power generation system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0061] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0062] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] In order to achieve the purpose of the present invention, some embodiments of a maximum power point tracking control method, device and storage medium for a wind power generation system are as follows: Figure 1 As shown, the maximum power point tracking control method of the wind power generation system includes the following contents: combining the three-phase commutation function of the brushless DC generator and utilizing the power converter switch switching technology, the wind power generation system can generate electricity at the maximum power point at any speed, as shown in formula (1):

[0064]

[0065] Among them, P m is the equivalent conversion power of the brushless DC generator;

[0066] V mis the equivalent DC dynamic model of the DC brushless generator;

[0067] I m is the equivalent DC armature current of the DC brushless generator;

[0068] The sliding plane is defined as shown in formula (2):

[0069]

[0070] When the system is in sliding mode state, S=0;

[0071] The sliding mode plane equivalent control Ueq is shown in equations (3)-(5):

[0072]

[0073]

[0074]

[0075] Among them: f(x) and g(x) are nonlinear functions;

[0076] U m is the maximum equivalent control function;

[0077] V 0 is the control voltage;

[0078] i L It controls the current.

[0079] Further, P m =P g , P g is the converter brushless DC generator power, obtained by the following;

[0080] The wind power generation system uses a three-phase DC brushless generator, and its dynamic equation is shown in equation (6);

[0081]

[0082] Among them, Rs is the coil resistance, L is the coil self-inductance, and M is the coil mutual inductance;

[0083] e a 、e b 、e c They represent the generator back EMF, i a 、i b 、i c Respectively represent the phase current, v a 、v b 、v c Respectively represent the terminal voltage;

[0084] Since the air gap flux density of the DC generator is designed to be a trapezoidal wave, the converter DC brushless generator power P g It is expressed as shown in formula (10);

[0085]

[0086]

[0087]

[0088] P g =e a i a +e b i b +e c i c ; (10)

[0089] Where: w e is a function of time;

[0090] K g and λ are coefficients;

[0091] t is time;

[0092] The three-phase commutation functions Sa(t), Sb(t), and Sc(t) of the brushless DC generator are shown in equations (11) to (13):

[0093]

[0094]

[0095]

[0096] Where u(t) is expressed as a unit step function and n is an integer;

[0097] Observe the three-phase current distribution and define the equivalent DC armature current i of the DC brushless generator eq (t) as shown in formula (14);

[0098]

[0099] Equivalent DC potential e of brushless DC generator eq (t) and terminal voltage V eq (t) are respectively expressed as shown in equations (15) and (16);

[0100]

[0101]

[0102] The equivalent DC internal potential e of the DC brushless generator can be obtained by the above formula eq Its conversion power Pg is shown in equations (17) and (18);

[0103] e eq =K g w e λ; (17)

[0104] P g =K g w e λi eq (18)

[0105] In formula (18), i eq and i in formula (14) eq (t)Same.

[0106] Further, I m =i eq .

[0107] Further, V m =V eq ;

[0108] Substituting equations (14)-(16) into equation (6), we can obtain the equivalent DC dynamic equation of the brushless DC generator. The dynamic equation V eq The expression method is shown in formula (19):

[0109]

[0110] From the above derivation of the equivalent DC equation, it can be found that by defining the commutation function, the mathematical relationship between the three-phase voltage, current and internal potential of the DC brushless generator, an equivalent DC dynamic mathematical model can be used to describe it, and the equivalent circuit is the same as the dynamic equation of the traditional brushed DC motor.

[0111] On the other hand, an embodiment of the present invention further discloses a maximum power point tracking control device for a wind power generation system, which uses the maximum power point tracking control method for a wind power generation system disclosed in any of the above embodiments to control the wind power generation system to maintain maximum power point power generation at different rotation speeds.

[0112] On the other hand, an embodiment of the present invention further discloses a storage medium, wherein one or more programs include instructions, and the instructions are suitable for being loaded by a memory and executing the maximum power point tracking control method for a wind power generation system disclosed in any of the above embodiments.

[0113] It should be understood that the various techniques described herein can be implemented in combination with hardware or software, or a combination thereof. Thus, the method and apparatus of the present invention, or certain aspects or portions of the method and apparatus of the present invention, can take the form of program code (i.e., instructions) embedded in a tangible medium, such as a floppy disk, a CD-ROM, a hard disk drive, or any other machine-readable storage medium, wherein when the program is loaded into a machine such as a computer and executed by the machine, the machine becomes a device for practicing the present invention.

[0114] The wind power generation system of the present invention adopts a three-phase DC brushless generator. Compared with the prior art, the present invention has the following beneficial effects:

[0115] (1) Since the generator of a wind power generation system has a nonlinear power-to-voltage characteristic and the output result of the generator power-voltage characteristic is affected by the wind speed, in order to enable the wind power generation system to continuously maintain the maximum power point at different speeds for power generation to improve power generation efficiency, the present invention proposes the application of improved sliding mode control to the maximum power point tracking of the wind power generation system.

[0116] (2) The present invention can effectively solve the shortcomings of poor robustness of traditional maximum power point tracking methods, perturbation observation method and incremental conductance method, and has better accuracy and stability.

[0117] (3) The present invention can effectively prevent the control input value from being in a saturated state for a long time, or switching between two saturated values ​​at a high speed, which may affect the life of the switching switch in the controller or cause high-frequency switching noise.

[0118] (4) The overall efficiency of the present invention is significantly improved in stability compared to traditional sliding mode control, and the response speed is also improved.

[0119] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A maximum power point tracking control method for a wind power generation system, characterized in that: Includes the following: Combined with the three-phase commutation function of the brushless DC generator and using the power converter switch technology, the wind power generation system can generate electricity at the maximum power point at any speed, as shown in formula (1): Among them, P m is the equivalent conversion power of the brushless DC generator; V m is the equivalent DC dynamic model of the brushless DC generator; I m is the equivalent DC armature current of the DC brushless generator; The sliding plane is defined as shown in formula (2): When the system is in sliding mode state, S=0; The sliding mode plane equivalent control Ueq is shown in equations (3)-(5): Where: x is the normal vector of the sliding plane; f(x) and g(x) are nonlinear functions; U m is the maximum equivalent control function; V0 is the control voltage; i L It controls the current; P m =P g , P g is the converter brushless DC generator power, obtained by the following; The wind power generation system adopts a three-phase brushless DC generator, and the dynamic equation of the three-phase brushless DC generator is shown in formula (6); Among them, Rs is the coil resistance, L is the coil self-inductance, and M is the coil mutual inductance; e a 、e b 、e c They represent the generator back EMF, i a 、i b 、i c Respectively represent the phase current, v a 、v b 、v c Respectively represent the terminal voltage; Since the air gap flux density of the DC generator is designed to be a trapezoidal wave, the converter DC brushless generator power P g It is expressed as shown in formula (10); P g =e a and a +e b and b +e c and c (10) Where: w e is the angular velocity; K g and λ are coefficients; t is time; The three-phase commutation functions Sa(t), Sb(t), and Sc(t) of the brushless DC generator are shown in equations (11) to (13): Where u(t) is expressed as a unit step function and n is an integer; Equivalent DC armature current i of brushless DC generator eq (t) as shown in formula (14); Equivalent DC potential e of brushless DC generator eq (t) and terminal voltage V eq (t) are respectively expressed as shown in equations (15) and (16); The equivalent DC internal potential e of the DC brushless generator can be obtained by the above formula eq Its conversion power Pg is expressed as shown in equations (17) and (18); e eq =K g w e l; (17) P g =K g w e λi eq ; (18) I m =i eq ; V m =V eq , V eq Through formula (19), we get: 。 2. A maximum power point tracking control device for a wind power generation system, characterized in that: The wind power generation system is controlled by the maximum power point tracking control method as claimed in claim 1, so that the wind power generation system maintains the maximum power point power generation at different rotation speeds.

3. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes one or more programs, and the one or more programs include instructions, and the instructions are suitable for being loaded by the memory and executing the maximum power point tracking control method of the wind power generation system according to claim 1.

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