Grid-connected robust control method and system for doubly-fed asynchronous wind generator

Abstract

The invention belongs to the technical field of electronic information, and relates to a doubly-fed asynchronous wind driven generator grid-connected robust control method and system, and the method comprises the steps: constructing a doubly-fed asynchronous wind driven generator grid-connected structure, and determining a state equation of the structure based on a value mathematics theory and the grid-connected structure; converting the state equation into a linear equation; obtaining a state-space equation and a parameter uncertainty equation under nominal parameters according to the linear equation; combining the parameter uncertainty equation with the state-space equation under the nominal parameter in a feedback form to obtain a comprehensive state-space equation; converting the comprehensive state-space equation into a transfer function form, and establishing a generalized controlled object of a mixed sensitivity mathematical theory based on a mu value; a D-K iteration method is adopted to solve the linear fractional transformation closed-loop transfer function, a transfer function of the controller is obtained, a doubly-fed asynchronous wind generator grid-connected robust controller is obtained, doubly-fed asynchronous wind generator grid-connected robust control is achieved, and the problem that in the prior art, when rotor current and stator current change, air gap magnetomotive force changes non-linearly, and power consumption is low is solved. And the stability of the control system is influenced.

Description

Technical Field

[0001] The invention belongs to the field of electronic information technology, and in particular relates to a grid-connected robust control method and system for a doubly-fed asynchronous wind turbine generator. Background Art

[0002] Usually, when a doubly-fed asynchronous wind turbine is connected to the grid, the stator output voltage is indirectly controlled by adjusting the excitation current of the rotor coil. The output power of the wind turbine is controlled by adjusting the active and reactive components of the excitation current to achieve a balance between mechanical power and electromagnetic power. At present, the rotor current control is based on the Park change and is adjusted using a PI controller. The PI parameters use the empirical value method and the trial and error method, which takes a long time to debug and does not consider the stability of the system under parameter changes. Due to the magnetic saturation phenomenon of ferromagnetic materials, when the rotor current and stator current change, the air gap magnetomotive force changes nonlinearly, which easily affects the stability of the control system. Summary of the invention

[0003] The object of the present invention is to provide a doubly-fed asynchronous wind generator grid-connected robust control method to solve the technical problem in the prior art that when the rotor current and the stator current change, the air gap magnetomotive force changes nonlinearly, which easily affects the stability of the control system.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A doubly-fed asynchronous wind turbine generator grid-connected robust control method comprises the following steps:

[0006] Constructing a grid-connected structure of a doubly-fed asynchronous wind turbine generator, and determining the state equation of the structure according to the grid-connected structure of the doubly-fed asynchronous wind turbine generator;

[0007] The state equation is converted into a linear equation; the state space equation and the parameter uncertainty equation under the nominal parameters are obtained according to the linear equation; the parameter uncertainty equation is combined with the state space equation under the nominal parameters in the form of feedback to obtain a linear comprehensive state space equation;

[0008] The comprehensive state-space equation is converted into a transfer function form, and a generalized controlled object based on the mixed sensitivity mathematical theory of μ value is established; the DK iteration method is used to solve the linear fractional transformation closed-loop transfer function to obtain the parameters of the controller, and a grid-connected robust controller of a doubly-fed asynchronous wind turbine is designed according to the parameters to achieve grid-connected robust control of the doubly-fed asynchronous wind turbine.

[0009] Preferably, the state equation of the structure is determined according to the grid-connected structure of the doubly-fed asynchronous wind turbine generator, specifically:

[0010] According to the mathematical model of the grid-connected structure of the doubly-fed asynchronous wind turbine generator, the circuit state space equation is obtained as follows:

[0011]

[0012] The rotor torque equation is:

[0013]

[0014] The overall state equation is:

[0015]

[0016] The total state equation is simplified to obtain the simplified total state equation:

[0017]

[0018] Convert to standard form:

[0019]

[0020] Output selection is The control target is

[0021] Among them, L s — stator coil self-inductance; L r — rotor coil self-inductance; L m — Mutual inductance between stator coil and rotor coil; R s — stator coil resistance; R r —Rotor coil resistance; ω s — stator synthetic magnetic field speed; ω r —rotor speed; J—rotor moment of inertia; n—rotor moment of inertia; T m —Mechanical torque obtained by the rotor; i ds —direct axis component of stator current; i qs — quadrature-axis component of stator current; i dr —direct axis component of rotor current; i qr — quadrature-axis component of rotor current; v ds —direct axis component of stator voltage; v qs — stator voltage quadrature axis component; v dr —direct axis component of rotor voltage; v qr —The quadrature-axis component of the rotor voltage; i—the total expression of all current components.

[0022] Preferably, the state equation is converted into a linear equation, specifically:

[0023] According to the coordinate transformation principle, the state equation is linearized and

[0024]

[0025] have to

[0026] z'=Az+Bu

[0027] Among them, A and B matrices are coefficient matrices; z is the original state vector; is the inverse of the original state vector; z' is the transformed state vector; u is the control input.

[0028] Preferably, the state space equation and parameter uncertainty equation under nominal parameters are obtained according to the linear equation, specifically:

[0029] Taking the inductance parameter L s , L m , L r According to the change of air gap magnetic density as the perturbation parameter, the state space equation under nominal parameters is obtained according to the linear equation:

[0030]

[0031] The feedback equation of the uncertainty equation is

[0032]

[0033] in, is the input of parameter perturbation; is the output of parameter perturbation; is the state matrix under the nominal state; is the state quantity of the generalized controlled object with parameter perturbation; is the parameter perturbation matrix; the value range of Δ1, Δ2, Δ3 is [0,1].

[0034] Preferably, the parameter uncertainty equation is combined with the state space equation under the nominal parameters in the form of feedback to obtain a linear comprehensive state space equation, specifically:

[0035]

[0036] δ u =Δδ y

[0037] in, is the inverse of the transformed state vector; z is the original state vector; δ y is the input vector of the uncertain block, i.e., the output vector of the generalized controlled object; u is the input vector of the generalized controlled object; y is the output vector of the generalized controlled object; δ uis the output vector of the uncertain block, that is, the input vector of the generalized controlled object; z' is the transformed state vector; Δ is the coefficient matrix of the uncertain block; A, B, C, and D are all coefficient matrices.

[0038] Preferably, the comprehensive state space equation is converted into a transfer function form to establish a generalized controlled object based on the mixed sensitivity mathematical theory of μ value, specifically:

[0039]

[0040] δ u =Δ(s)δ y

[0041] in

[0042]

[0043] f1 is the controllable input vector, and the rotor coil input voltage v dr 、v qr , wind turbine mechanical torque T m ; f2 is the uncontrollable input quantity vector, the stator coil output voltage, that is, the grid connection point voltage v ds 、v qs ;ω n is the reference value of the output quantity, which refers to the rate of change of the rotor speed per unit time in this model; z1 and z2 are control performance evaluation indicators, z1 is the difference between the rate of change of the rotor speed per unit time and the given value, and z2 is the size of the controllable input quantity; P(s) is the transfer function of the generalized controlled object; u is the input vector of the generalized controlled object; y is the output vector.

[0044] Preferably, the DK iteration method is used to solve the linear fractional transformation closed-loop transfer function to obtain the parameters of the controller, which are specifically:

[0045] The DK iteration method is used to solve the following equation:

[0046]

[0047] The solution is:

[0048]

[0049] Where P(s) is the generalized controlled object transfer function; δ is the coefficient matrix of the uncertain block; K μ is the transfer function of the controller; a0~a4, b0~b5 are constant coefficients, all of which are solved by the DK iteration method.

[0050] In a second aspect, the present application discloses a doubly-fed asynchronous wind turbine grid-connected robust control system, comprising:

[0051] A state equation construction unit is used to construct a grid-connected structure of a double-fed asynchronous wind generator, and determine a state equation of the structure according to the grid-connected structure of the double-fed asynchronous wind generator;

[0052] A linear conversion unit is used to convert the state equation into a linear equation; obtain the state space equation and the parameter uncertainty equation under the nominal parameters according to the linear equation; combine the parameter uncertainty equation with the state space equation under the nominal parameters in the form of feedback to obtain the linear comprehensive state space equation;

[0053] The solving unit is used to convert the comprehensive state space equation into the transfer function form and establish a generalized controlled object based on the mixed sensitivity mathematical theory of μ value; the DK iteration method is used to solve the linear fractional transformation closed-loop transfer function to obtain the parameters of the controller, and the grid-connected robust controller of the doubly fed asynchronous wind turbine is designed according to the parameters to realize the grid-connected robust control of the doubly fed asynchronous wind turbine.

[0054] In a third aspect, the present application discloses an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for robust grid-connected control of a doubly-fed asynchronous wind turbine as described in any one of the above items when executing the computer program.

[0055] In a fourth aspect, the present application discloses a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for robustly controlling a doubly-fed asynchronous wind turbine connected to the grid are implemented as described in any one of the above items.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] 1) Through the principle of coordinate transformation, the nonlinear state space equation is transformed into a linear state space equation to achieve decoupling control of state quantity and control quantity.

[0058] 2) By introducing parameter perturbations into the control object in the form of uncertain parameter blocks, the linear comprehensive state space equation of the generalized controlled object is obtained. Since parameter perturbations have been considered when designing the controller, the system has strong robustness.

[0059] 3) Based on the mathematical theory of μ value, the mechanical torque and electromagnetic torque balance control problem is transformed into a mixed sensitivity problem, in which the infinite norm characterizes the disturbance suppression performance of the controller. Therefore, the physical meaning is clear, and this method can avoid controller saturation and ensure disturbance suppression performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] 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.

[0061] Figure 1 is a flow chart of the method of the present invention;

[0062] Figure 2 A schematic diagram of a grid-connected structure model of a double-fed asynchronous wind turbine generator according to the present invention;

[0063] Figure 3 It is a schematic diagram of the mixed sensitivity problem model based on μ value theory of the present invention.

[0064] Among them, 1-wind turbine; 2-transformer; 3-grid connection point; 4-RL filter DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0066] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0067] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0068] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0069] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0070] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0071] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0072] See also Figure 1 The present application discloses a grid-connected robust control method for a doubly-fed asynchronous wind turbine generator, comprising the following steps:

[0073] S1: Construct a grid-connected structure of a doubly-fed asynchronous wind turbine generator, and determine the state equation of the structure based on the μ value mathematical theory and the grid-connected structure of a doubly-fed asynchronous wind turbine generator;

[0074] S2: Convert the state equation into a linear equation; obtain the uncertainty parameter block state space equation and the uncertainty feedback equation according to the linear equation; combine the linear equation, the uncertainty parameter block state space equation and the uncertainty feedback to obtain the linear comprehensive state space equation;

[0075] S3: The DK iteration method is used to solve the linear fractional transformation closed-loop transfer function to obtain the parameters of the controller. A grid-connected robust controller for a doubly-fed asynchronous wind turbine is designed based on the parameters to achieve grid-connected robust control of the doubly-fed asynchronous wind turbine.

[0076] Based on the mathematical theory of μ value, this application transforms the mechanical torque and electromagnetic torque balance control problem into a mixed sensitivity problem, in which the infinite norm characterizes the interference suppression performance of the controller. Therefore, the physical meaning is clear, and this method can avoid controller saturation and ensure interference suppression performance; by introducing parameter perturbations into the control object in the form of uncertain parameter blocks, the linear comprehensive state space equation of the generalized controlled object is obtained. Since parameter perturbations have been considered when designing the controller, the system has strong robustness; through the principle of coordinate transformation, the nonlinear state space equation is transformed into a linear state space equation to achieve decoupled control of state quantity and control quantity.

[0077] In some embodiments, the state equation of the structure is determined according to the grid-connected structure of the doubly-fed asynchronous wind turbine generator, specifically:

[0078] According to the mathematical model of the grid-connected structure of the doubly-fed asynchronous wind turbine generator, the circuit state space equation is obtained as follows:

[0079]

[0080] The rotor torque equation is:

[0081]

[0082] The overall state equation is:

[0083]

[0084] The total state equation is simplified to obtain the simplified total state equation:

[0085]

[0086] Convert to standard form:

[0087]

[0088] Output selection is The control target is

[0089] Among them, L s — stator coil self-inductance; L r — rotor coil self-inductance; L m — Mutual inductance between stator coil and rotor coil; R s — stator coil resistance; R r —Rotor coil resistance; ω s — stator synthetic magnetic field speed; ω r —rotor speed; J—rotor moment of inertia; n—rotor moment of inertia; T m —Mechanical torque obtained by the rotor; i ds —direct axis component of stator current; iqs — quadrature-axis component of stator current; i dr —direct axis component of rotor current; i qr — quadrature-axis component of rotor current; v ds —direct axis component of stator voltage; v qs — stator voltage quadrature axis component; v dr —direct axis component of rotor voltage; v qr —The quadrature-axis component of the rotor voltage; i—the total expression of all current components.

[0090] In some embodiments, the state equation is converted into a linear equation, specifically:

[0091] According to the coordinate transformation principle, the state equation is linearized and

[0092]

[0093] have to

[0094] z'=Az+Bu

[0095] Among them, A and B matrices are coefficient matrices; z is the original state vector; is the inverse of the original state vector; z' is the transformed state vector; u is the control input.

[0096] By using the coordinate transformation principle to linearize the state equation, the complexity of the system can be reduced by linearizing the nonlinear system, making it easier to optimize and control the system. After linearizing the nonlinear system, these theories can be easily applied to design the control system.

[0097] In some embodiments, the state space equation and parameter uncertainty equation under nominal parameters are obtained according to the linear equation, specifically:

[0098] Taking the inductance parameter L s , L m , L r According to the change of air gap magnetic density as the perturbation parameter, the state space equation under nominal parameters is obtained according to the linear equation:

[0099]

[0100] The feedback equation for the parameter uncertainty equation is

[0101]

[0102] in, is the input of parameter perturbation; is the output of parameter perturbation; is the state matrix under the nominal state; is the state quantity of the generalized controlled object with parameter perturbation; is the parameter perturbation matrix; the value range of Δ1, Δ2, and Δ3 is [0, 1]. The state space equation under nominal parameters expresses the relationship between the state variables, inputs, and outputs of the system in matrix form, providing a powerful mathematical tool for system analysis and control.

[0103] In some embodiments, the parameter uncertainty equation is combined with the state space equation under the nominal parameters in the form of feedback to obtain a linear comprehensive state space equation, specifically:

[0104]

[0105] δ u =Δδ y

[0106] in, is the inverse of the transformed state vector; z is the original state vector; δ y is the input vector of the uncertain block, i.e., the output vector of the generalized controlled object; u is the input vector of the generalized controlled object; y is the output vector of the generalized controlled object; δ u is the output vector of the uncertain block, that is, the input vector of the generalized controlled object; z' is the transformed state vector; Δ is the coefficient matrix of the uncertain block; A, B, C, and D are all coefficient matrices.

[0107] In some embodiments, the comprehensive state space equation is converted into a transfer function form to establish a generalized controlled object based on the mixed sensitivity mathematical theory of μ value, specifically:

[0108]

[0109] δ u =Δ(s)δ y

[0110] in

[0111]

[0112] f1 is the controllable input vector, and the rotor coil input voltage v dr 、v qr , wind turbine mechanical torque T m ; f2 is the uncontrollable input quantity vector, the stator coil output voltage, that is, the grid connection point voltage v ds 、v qs ;ω nis the reference value of the output quantity, which refers to the rate of change of the rotor speed per unit time in this model; z1 and z2 are control performance evaluation indicators, z1 is the difference between the rate of change of the rotor speed per unit time and the given value, and z2 is the size of the controllable input quantity; P(s) is the transfer function of the generalized controlled object; u is the input vector of the generalized controlled object; y is the output vector.

[0113] In some embodiments, the DK iteration method is used to solve the linear fractional transformation closed-loop transfer function to obtain the parameters of the controller, specifically:

[0114] The DK iteration method is used to solve the following equation:

[0115]

[0116] The solution is:

[0117]

[0118] in, is the inverse of the transformed state vector; z is the original state vector; is the inverse of the state vector, δ y is the input vector of the uncertain block, i.e., the output vector of the generalized controlled object; u is the input vector of the generalized controlled object; δ u is the output vector of the uncertain block, i.e., the input vector of the generalized controlled object; Δ is the coefficient matrix of the uncertain block; P(s) is the transfer function of the generalized controlled object; δ is the coefficient matrix of the uncertain block; K μ is the transfer function of the controller; a0~a4, b0~b5 are constant coefficients, all of which are solved by the DK iteration method.

[0119] In some embodiments, a method for robustly controlling a doubly-fed asynchronous wind turbine generator connected to the grid includes:

[0120] 1. Description of the grid-connected model of double-fed asynchronous wind turbine generator

[0121] The research objectives are Figure 2 The dynamic structure diagram of the doubly-fed wind power grid-connected system is shown in the figure. The AC / DC converter adopts constant power control, and achieves maximum wind power tracking by adjusting the active and reactive components of the rotor current. In addition, adjusting the frequency of the excitation current can achieve constant frequency power generation at different speeds to meet the requirements of power load and grid connection. The DC / AC converter adopts constant DC voltage control, and ensures the constant DC bus voltage by adjusting the size of the grid-connected current (or the size of the absorbed current).

[0122] 2. Mathematical theory of mixed sensitivity based on μ value

[0123] Figure 3is a mixed sensitivity problem model based on μ value theory, and the mathematical model of the nominal object is M(s). f1 is the controllable input; f2 is the uncontrollable input; z1 and z2 are performance evaluation indicators, W n , W u , W p , W dist is the weight function, specifically W n is the reference value weight function, W u is the control input bandpass filter weight function, W p Tracking reference value performance evaluation index weight function, W dist Uncontrollable input bandpass filter weight function. δ y is the input vector of the uncertain block, i.e., the output vector of the generalized controlled object; u is the input vector of the generalized controlled object; δ u is the output vector of the uncertain block, i.e., the input vector of the generalized controlled object; Δ is the coefficient matrix of the uncertain block; K μ is the transfer function of the controller; the transfer function of the generalized controlled object is shown in equations (1) and (2).

[0124]

[0125] δ u =Δδ y (2)

[0126] make

[0127]

[0128] The transfer function of the interference factor ω is shown in formula (2):

[0129]

[0130] According to the sensitivity minimization theory, when the influence of ω on the desired output z is minimized, the closed-loop system is stable under the designed controller K(s).

[0131]

[0132] 3. Doubly-fed asynchronous wind turbine generator system control problem based on μ value mathematical theory

[0133] In this case, the physical mechanism of the double-fed asynchronous wind turbine generator power generation control is transformed into a mixed sensitivity problem based on μ value theory. Among them, f1 is the controllable input vector, and the rotor coil input voltage v dr 、v qr , wind turbine mechanical torque T m ; f2 is the uncontrollable input quantity vector, the stator coil output voltage, that is, the grid connection point voltage v ds 、vqs ;ω n is the output reference value, which refers to the rotor speed change rate per unit time in this model; z1 and z2 are control performance evaluation indicators, z1 is the difference between the rotor speed change rate per unit time and the given value, and z2 is the size of the controllable input. n ] T to [z1 z2] T The closed-loop transfer function is S. The sensitivity minimization problem in this paper is to minimize the influence of mechanical torque fluctuation and grid-connected point voltage fluctuation of doubly-fed asynchronous wind turbine on the rate of change of rotor speed per unit time.

[0134] (1) Equation of state

[0135] according to Figure 2 Mathematical model, the state space equation of the electrical part is as follows:

[0136]

[0137] The rotor torque equation is:

[0138]

[0139] The overall state equation is:

[0140]

[0141] Simplified to:

[0142]

[0143] Convert to standard form:

[0144]

[0145] Output selection is The control target is

[0146] Among them, L s — stator coil self-inductance; L r — rotor coil self-inductance; L m — Mutual inductance between stator coil and rotor coil; R s — stator coil resistance; R r —Rotor coil resistance; ω s — stator synthetic magnetic field speed; ω r —rotor speed; J—rotor moment of inertia; n—rotor moment of inertia; T m —Mechanical torque obtained by the rotor; i ds —direct axis component of stator current; i qs — quadrature-axis component of stator current; i dr—direct axis component of rotor current; i qr — quadrature-axis component of rotor current; v ds —direct axis component of stator voltage; v qs — stator voltage quadrature axis component; v dr —direct axis component of rotor voltage; v qr — rotor voltage quadrature axis component; i—total expression of each current component

[0147] (2) Linearization of nonlinear problems

[0148] According to the coordinate transformation principle, the state equation is linearized and

[0149]

[0150] have to

[0151] z'=Az+Bu

[0152] Among them, A and B matrices are constant matrices; z is the original state vector; is the inverse of the original state vector; z' is the transformed state vector; u is the control input.

[0153] (3) Uncertain block state space equations and uncertainty feedback

[0154] In the system, the inductance parameter L s , L m , L r It will change according to the air gap magnetic density and is the perturbation parameter. Introducing the perturbation parameter, the state space equation under the nominal parameter is

[0155]

[0156] The feedback equation of the uncertainty equation is

[0157] The value range of Δ1, Δ2, and Δ3 is [0,1].

[0158] (4) Comprehensive state space equation

[0159]

[0160] δ u =Δδ y

[0161] in,

[0162] is the inverse of the transformed state vector; z is the original state vector; δ y is the input vector of the uncertain block, i.e., the output vector of the generalized controlled object; u is the input vector of the generalized controlled object; δ uis the output vector of the uncertain block, that is, the input vector of the generalized controlled object; Δ is the coefficient matrix of the uncertain block; z' is the transformed state vector; A, B, C, and D are all coefficient matrices.

[0163] (5) The comprehensive state space equation is converted into the transfer function form, and the generalized controlled object is established based on the mathematical theory of mixed sensitivity of μ value.

[0164]

[0165] δ u =Δ(s)δ y

[0166] in

[0167]

[0168] f1 is the controllable input vector, and the rotor coil input voltage v dr 、v qr , wind turbine mechanical torque T m ; f2 is the uncontrollable input quantity vector, the stator coil output voltage, that is, the grid connection point voltage v ds 、v qs ;ω n is the reference value of the output quantity, which refers to the rate of change of the rotor speed per unit time in this model; z1 and z2 are control performance evaluation indicators, z1 is the difference between the rate of change of the rotor speed per unit time and the given value, and z2 is the size of the controllable input quantity; P(s) is the transfer function of the generalized controlled object; u is the input vector of the generalized controlled object; y is the output vector.

[0169] 4. Solve the controller transfer function

[0170] Using DK Iteration Method to Solve the Closed-Loop Transfer Function of Linear Fractional Transformation Available controller K μ Each parameter in .

[0171]

[0172] Among them, K μ is the transfer function of the controller, a0~a4 and b0~b5 are constant coefficients, all of which are solved by the DK iteration method.

[0173] In summary, the present application discloses a method for robust control of a doubly-fed asynchronous wind turbine connected to the grid. Through the principle of coordinate transformation, the present application can transform complex nonlinear state space equations into more easily processable linear state space equations. This transformation not only simplifies the analysis process of the system, but also enables decoupling control between the state quantity and the control quantity. Decoupling control means that each state and control input of the system can be adjusted independently without interfering with each other, thereby improving the control accuracy and stability of the system. In practical applications, there are often certain perturbations in system parameters. In order to enhance the robustness of the system, the present application introduces these parameter perturbations into the control object in the form of uncertainty parameter blocks, thereby obtaining a generalized linear comprehensive state space equation. This method takes into account the uncertainty of parameters when designing the controller, so it can cope with parameter changes within a certain range and ensure the stability and performance of the system. Using the μ value mathematical theory, the present application can transform the balance control problem of mechanical torque and electromagnetic torque into a mixed sensitivity problem. By solving this problem, the present application can obtain a controller with clear physical meaning, and its infinite norm can characterize the interference suppression performance of the controller. This method not only avoids the saturation problem of the controller, but also ensures the stability and interference suppression capability of the system when interference exists. It realizes the grid-connected robust control of the doubly-fed asynchronous wind turbine generator and solves the problem in the prior art that when the rotor current and stator current change, the air gap magnetomotive force changes nonlinearly, affecting the stability of the control system.

[0174] The present application discloses a double-fed asynchronous wind turbine grid-connected robust control system, comprising:

[0175] A state equation construction unit is used to construct a grid-connected structure of a double-fed asynchronous wind generator, and determine a state equation of the structure according to the grid-connected structure of the double-fed asynchronous wind generator;

[0176] A linear conversion unit is used to convert the state equation into a linear equation; obtain the state space equation and the parameter uncertainty equation under the nominal parameters according to the linear equation; combine the parameter uncertainty equation with the state space equation under the nominal parameters in the form of feedback to obtain the linear comprehensive state space equation;

[0177] The solving unit is used to convert the comprehensive state space equation into the transfer function form and establish a generalized controlled object based on the mixed sensitivity mathematical theory of μ value; the DK iteration method is used to solve the linear fractional transformation closed-loop transfer function to obtain the parameters of the controller, and the grid-connected robust controller of the doubly fed asynchronous wind turbine is designed according to the parameters to realize the grid-connected robust control of the doubly fed asynchronous wind turbine.

[0178] The present application discloses an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for robustly controlling a doubly-fed asynchronous wind generator connected to the grid are implemented.

[0179] The present application discloses a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of any of the above-mentioned methods for robustly controlling a doubly-fed asynchronous wind turbine connected to the grid are implemented.

[0180] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0181] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0182] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0183] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0184] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A doubly-fed asynchronous wind turbine grid-connected robust control method, characterized in that: The following steps are involved: Constructing a grid-connected structure of a doubly-fed asynchronous wind turbine generator, and determining the state equation of the structure according to the grid-connected structure of the doubly-fed asynchronous wind turbine generator; The state equation is converted into a linear equation; the state space equation and the parameter uncertainty equation under the nominal parameters are obtained according to the linear equation; the parameter uncertainty equation is combined with the state space equation under the nominal parameters in the form of feedback to obtain a linear comprehensive state space equation; The comprehensive state-space equation is converted into a transfer function form, and a generalized controlled object based on the mixed sensitivity mathematical theory of μ value is established; the DK iteration method is used to solve the linear fractional transformation closed-loop transfer function to obtain the parameters of the controller, and a grid-connected robust controller of a doubly-fed asynchronous wind turbine is designed according to the parameters to achieve grid-connected robust control of the doubly-fed asynchronous wind turbine.

2. A method for controlling a double-fed asynchronous wind turbine connected to the grid according to claim 1, characterized in that: The state equation of the structure is determined according to the grid-connected structure of the doubly-fed asynchronous wind turbine generator, specifically: According to the mathematical model of the grid-connected structure of the doubly-fed asynchronous wind turbine generator, the circuit state space equation is obtained as follows: The rotor torque equation is: The overall state equation is: The total state equation is simplified to obtain the simplified total state equation: Convert to standard form: Output selection is The control target is Among them, L s — stator coil self-inductance; L r — rotor coil self-inductance; L m — Mutual inductance between stator coil and rotor coil; R s — stator coil resistance; R r —Rotor coil resistance; ω s — stator synthetic magnetic field speed; ω r —rotor speed; J—rotor moment of inertia; n—rotor moment of inertia; T m —Mechanical torque obtained by the rotor; i ds —direct axis component of stator current; i qs — quadrature-axis component of stator current; i dr —direct axis component of rotor current; i qr — quadrature-axis component of rotor current; v ds —direct axis component of stator voltage; v qs — stator voltage quadrature axis component; v dr —direct axis component of rotor voltage; v qr —The quadrature-axis component of the rotor voltage; i—the total expression of all current components.

3. A method for controlling a double-fed asynchronous wind turbine connected to the grid according to claim 1, characterized in that: The state equation is converted into a linear equation, specifically: According to the coordinate transformation principle, the state equation is linearized and have to z'=Az+Bu Among them, A and B matrices are coefficient matrices; z is the original state vector; is the inverse of the original state vector; z' is the transformed state vector; u is the control input.

4. A method for controlling a double-fed asynchronous wind turbine connected to the grid according to claim 1, characterized in that: The state space equation and parameter uncertainty equation under nominal parameters are obtained according to the linear equation, which are specifically: Taking the inductance parameter L s , L m , L r According to the change of air gap magnetic density as the perturbation parameter, the state space equation under nominal parameters is obtained according to the linear equation: The feedback equation for the parameter uncertainty equation is in, is the input of parameter perturbation; is the output of parameter perturbation; is the state matrix under the nominal state; is the state quantity of the generalized controlled object with parameter perturbation; is the parameter perturbation matrix; the value range of Δ1, Δ2, Δ3 is [0,1].

5. The method for controlling a doubly-fed asynchronous wind turbine generator connected to the grid according to claim 1, characterized in that: The parameter uncertainty equation is combined with the state space equation under the nominal parameters in the form of feedback to obtain the linear comprehensive state space equation, which is specifically: d u =Dd y in, is the inverse of the transformed state vector; z is the original state vector; δ y is the input vector of the uncertain block, i.e., the output vector of the generalized controlled object; u is the input vector of the generalized controlled object; y is the output vector of the generalized controlled object; δ u is the output vector of the uncertain block, that is, the input vector of the generalized controlled object; z' is the transformed state vector; Δ is the coefficient matrix of the uncertain block; A, B, C, and D are all coefficient matrices.

6. A method for controlling a double-fed asynchronous wind turbine connected to the grid according to claim 1, characterized in that: The comprehensive state space equation is converted into a transfer function form to establish a generalized controlled object based on the mixed sensitivity mathematical theory of μ value, specifically: d u =Δ(s)δ y in f1 is the controllable input vector, and the rotor coil input voltage v dr 、v qr , wind turbine mechanical torque T m ; f2 is the uncontrollable input quantity vector, the stator coil output voltage, that is, the grid connection point voltage v ds 、v qs ; ω n is the reference value of the output quantity, which refers to the rate of change of the rotor speed per unit time in this model; z1 and z2 are control performance evaluation indicators, z1 is the difference between the rate of change of the rotor speed per unit time and the given value, and z2 is the size of the controllable input quantity; P(s) is the transfer function of the generalized controlled object; u is the input vector of the generalized controlled object; y is the output vector.

7. A method for controlling a double-fed asynchronous wind turbine connected to the grid according to claim 1, characterized in that: The DK iteration method is used to solve the linear fractional transformation closed-loop transfer function to obtain the parameters of the controller, which are specifically: The DK iteration method is used to solve the following equation: The solution is: Where P(s) is the generalized controlled object transfer function; δ is the coefficient matrix of the uncertain block; K μ is the transfer function of the controller; a0~a4, b0~b5 are constant coefficients, all of which are solved by the DK iteration method.

8. A doubly-fed asynchronous wind turbine grid-connected robust control system, characterized in that: The following steps are involved: A state equation construction unit is used to construct a grid-connected structure of a double-fed asynchronous wind generator, and determine a state equation of the structure according to the grid-connected structure of the double-fed asynchronous wind generator; A linear conversion unit is used to convert the state equation into a linear equation; obtain the state space equation and the parameter uncertainty equation under the nominal parameters according to the linear equation; combine the parameter uncertainty equation with the state space equation under the nominal parameters in the form of feedback to obtain the linear comprehensive state space equation; The solving unit is used to convert the comprehensive state space equation into the transfer function form and establish a generalized controlled object based on the mixed sensitivity mathematical theory of μ value; the DK iteration method is used to solve the linear fractional transformation closed-loop transfer function to obtain the parameters of the controller, and the grid-connected robust controller of the doubly fed asynchronous wind turbine is designed according to the parameters to realize the grid-connected robust control of the doubly fed asynchronous wind turbine.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for robust grid-connected control of a doubly-fed asynchronous wind turbine generator as claimed in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the method for robust grid-connected control of a doubly-fed asynchronous wind turbine generator according to any one of claims 1 to 7.

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