阅读说明：本技术 一种开绕组无刷双馈发电机直接功率控制的方法 (Method for controlling direct power of open-winding brushless doubly-fed generator ) 是由 杨小亮 和萍 申永鹏 李从善 娄泰山 金楠 郭磊磊 邱洪波 王宇豪 孙建新 袁遇 于 2020-05-12 设计创作，主要内容包括：本发明公开一种开绕组无刷双馈发电机直接功率控制的方法,包括以下步骤：建立开绕组无刷双馈发电机的直接功率控制的数学模型；设计改进超扭曲滑模控制器,建立基于改进超扭曲滑模的开绕组无刷双馈发电机直接功率控制数学模型并进行基于Lyapunov函数的稳定性分析,并获取控制模型参数的范围；在控制模型参数的范围内任意取一组参数的组合进行仿真验证,若控制精度满足直接功率控制要求结束设计,否则,重新修正控制模型参数直至控制精度满足设计要求,将满足直接功率控制要求的控制模型参数代入基于改进超扭曲滑模的开绕组无刷双馈发电机直接功率控制数学模型中,获得准确的控制模型。本发明控制精度高,响应速度快,具有良好的动、静态性能和鲁棒性。(The invention discloses a method for controlling direct power of an open-winding brushless doubly-fed generator, which comprises the following steps: establishing a mathematical model for direct power control of the open-winding brushless doubly-fed generator; designing an improved super-distortion sliding mode controller, establishing an open-winding brushless doubly-fed generator direct power control mathematical model based on the improved super-distortion sliding mode, performing stability analysis based on a Lyapunov function, and acquiring a range of control model parameters; and (3) randomly selecting a group of parameter combinations within the range of control model parameters to carry out simulation verification, if the control precision meets the requirement of direct power control, finishing the design, otherwise, revising the control model parameters again until the control precision meets the design requirement, substituting the control model parameters meeting the requirement of direct power control into an open-winding brushless double-fed generator direct power control mathematical model based on an improved super-distortion sliding mode, and obtaining an accurate control model. The invention has high control precision, high response speed, good dynamic and static performances and robustness.)

1. A method for controlling direct power of an open-winding brushless doubly-fed generator is characterized by comprising the following steps:

establishing a mathematical model for direct power control of the open-winding brushless doubly-fed generator;

designing an improved super-distortion sliding mode controller, and establishing an open-winding brushless doubly-fed generator direct power control mathematical model based on an improved super-distortion sliding mode;

performing stability analysis based on a Lyapunov function on an open-winding brushless doubly-fed generator direct power control mathematical model based on an improved super-distortion sliding mode, and acquiring a range of control model parameters;

and (3) randomly selecting a group of parameter combinations within the range of control model parameters to carry out simulation verification, finishing the design if the control precision meets the requirement of direct power control, and otherwise, revising the control model parameters until the control precision meets the design requirement, substituting the control model parameters meeting the requirement of direct power control into an open-winding brushless double-fed generator direct power control mathematical model based on an improved super-distortion sliding mode to obtain an accurate control model.

2. The method for direct power control of an open-winding brushless doubly-fed generator as claimed in claim 1, wherein the step of establishing a mathematical model of the direct power control of the open-winding brushless doubly-fed generator comprises the steps of:

establishing a mathematical model of the open-winding brushless doubly-fed generator under a two-phase (d-q) rotating coordinate system, wherein the voltage and flux linkage equations are as follows:

wherein u is_dpAnd u_qpRespectively a d-axis voltage component and a q-axis voltage component i of a stator power winding under a d-q-axis rotating coordinate system_dpAnd i_qpD-axis and q-axis current components u under a d-q-axis rotating coordinate system of the power winding_dcAnd u_qcD-axis and q-axis voltage components, i, of a stator control winding in a d-q-axis rotating coordinate system_dcAnd i_qcD-axis and q-axis current components, psi, in a d-q-axis rotating coordinate system of the control winding_dpAnd psi_qpRespectively a d-axis flux linkage component and a q-axis flux linkage component psi under a d-q-axis rotating coordinate system of the stator power winding_dcAnd psi_qcRespectively are flux linkage components of a d axis and a q axis under a d-q axis rotating coordinate system of the control winding, Rp and Rc are respectively a power winding and a control winding resistor, Lp is a power winding self-inductance, Lc is a control winding self-inductance, Lm is a mutual inductance between the power winding and the control winding, omega is an angular velocity of the power winding in an arbitrary speed rotating reference coordinate system, and omega is an angular velocity of the power winding in an arbitrary speed rotating reference coordinate system_rD/dt is a differential operator for controlling the angular speed of the winding rotating reference coordinate system at any speed;

instantaneous active power P and reactive power Q output by a power winding of the open-winding brushless doubly-fed generator are defined based on an instantaneous power theory:

wherein P and Q are respectively the active power and the reactive power of the stator power winding, u_dpAnd u_qpD-axis and q-axis voltage components, i, in a d-q-axis rotating coordinate system of the power winding_dpAnd i_qpRespectively are d-axis current components and q-axis current components under a d-q-axis rotating coordinate system of the power winding;

will be at the synchronous speed omega_pRotating power winding reference axis system (d)_p-q_p) D of_pAxial orientation in power winding stator flux space vector psi_pIn the direction of phi at this time_dp＝ψ_p，ψ_qpWhen the value is 0, the relationship between the power winding current and the control winding flux linkage is derived from the formula (4):

wherein psi_qcFor controlling the q-component, psi, of the winding voltage in a d-q coordinate system_dcFor controlling the d-axis component, psi, of the winding voltage in a d-q-axis coordinate system_pIs the vector modulus, L, of the flux linkage of the power winding_pFor self-inductance of the power winding, L_cFor controlling the self-inductance of the winding, L_mFor mutual inductance between power winding and control winding, i_dpAnd i_qpRespectively are d-axis current components and q-axis current components under a d-q-axis rotating coordinate system of the power winding;

in the formula (6), u is substituted by the formula (7)_dp＝0，u_qp＝u_pThen, then

Wherein P and Q are respectively the active power and the reactive power of the stator power winding, u_pFor the vector norm value, psi, of the power winding voltage_pFor the flux linkage vector norm, psi, of the power winding_qcFor controlling the q-component, psi, of the winding voltage in a d-q coordinate system_dcFor controlling the d-axis component, L, of the winding voltage in a d-q-axis coordinate system_pFor self-inductance of the power winding, L_cFor controlling the self-inductance of the winding, L_mMutual inductance between the power winding and the control winding;

differentiating the time t, the derivative of the active and reactive power is expressed as:

and (3) converting the equation (9) into a space state to obtain a direct power control mathematical model of the open-winding brushless doubly-fed generator:

wherein P is the active power of the power winding, Q is the reactive power of the power winding, omega is the angular velocity of the power winding rotating at any speed in the reference coordinate system, omega_rFor controlling the angular velocity, u, of a reference frame of arbitrary-speed rotation of the windings_pFor the vector norm value, psi, of the power winding voltage_pIs the vector norm value of flux linkage of the power winding, u_qcFor controlling the q-component, u, of the winding voltage in a d-q coordinate system_dcFor controlling the d-axis component, L, of the winding voltage in a d-q-axis coordinate system_pFor self-inductance of the power winding, L_cTo control windingGroup self-inductance, L_mIs the mutual inductance between the power winding and the control winding.

3. The method for direct power control of an open-winding brushless doubly-fed generator according to claim 1, wherein the establishing of the open-winding brushless doubly-fed generator direct power control mathematical model based on the improved super-twisted sliding mode comprises the following steps:

selecting an instantaneous power error as a sliding mode surface, and defining a switching function:

wherein S is a sliding variable, S_PIs a sliding variable of the active power of the system power winding, i.e. the difference between the set value and the actual value of the active power, S_QAs a sliding variable of the reactive power of the power winding, i.e. the difference between the set value and the actual value of the reactive power, P^*，Q^*Respectively setting values of active power and reactive power of a system power winding, and respectively setting P and Q as actual values of the active power and the reactive power of the system power winding;

constructing a Lyapunov function V:

the time derivation of the Lyapunov function is as follows:

wherein S is a sliding variable;

the slip variable of equation (12) is derived over time:

wherein S is_PFor sliding variables of active power of system power windings, i.e. active power setpointDifference from the actual value, S_QThe sliding variable of the reactive power of the power winding, namely the difference between a given value and an actual value of the reactive power, wherein P and Q are the active power and the reactive power of the stator power winding respectively;

substituting formula (1) into formula (15) to obtain the time derivative of the sliding mode surface as follows:

wherein the content of the first and second substances,

p is the active power of the power winding, Q is the reactive power of the power winding, u_pFor power winding voltage vector, #_pAs flux linkage vector, L, of the power winding_pFor self-inductance of the power winding, L_cTo control the self-inductance of the winding, L_mIs mutual inductance between the power winding and the control winding, omega is the angular speed of the power winding rotating at any speed in a reference coordinate system, omega_rFor controlling the angular velocity, u, of a reference frame of arbitrary-speed rotation of the windings_qcFor controlling the q-component, u, of the winding voltage in a d-q coordinate system_dcIs D-axis component of control winding voltage in D-q-axis coordinate system, U is control winding voltage matrix, D is coefficient matrix, F₁And F₂Is a known term in the direct power control equation;

in order to ensure that dV/dt is less than 0, the improved supertorsion sliding mode control law is designed as follows:

where U is the control winding voltage matrix, D is the coefficient matrix, F₁And F₂As a known term in the direct power control equation, a₁、a₂、b₁、b₂Are the observer gain, S_PIs a sliding variable of the active power of the system power winding, i.e. the difference between the set value and the actual value of the active power, S_QThe sliding variable of the reactive power of the power winding, namely the difference between the given value and the actual value of the reactive power, is an adjusting coefficient.

4. The method for controlling the direct power of the open-winding brushless doubly-fed generator according to claim 1, wherein the stability analysis based on the Lyapunov function comprises the following steps:

stability analysis based on Lyapunov function:

substituting the formulas (16) and (2) into the formula (14):

wherein a1, a2, b1 and b2 are observer gains, S_PIs a sliding variable of the active power of the system power winding, i.e. the difference between the set value and the actual value of the active power, S_QThe sliding variable of the reactive power of the power winding, namely the difference between a given value and an actual value of the reactive power, is an adjusting coefficient;

judging whether dV/dt is less than 0, if dV/dt is less than 0, the function is negative definite function, and if dV/dt is greater than 0, the function is positive definite function;

when dV/dt<0, the system meets the Lyapunov gradual stabilization condition, S_P、S_QGradually approaching zero.

Technical Field

The invention belongs to the technical field of motor control, and particularly relates to a method for controlling direct power of an open-winding brushless doubly-fed generator.

Background

The brushless double-fed motor has the advantages of no electric brush, small capacity of a frequency converter, controllable power factor, reliable operation and the like, and has wide application prospect in the field of wind power generation. In 1989, japanese scholars proposed open winding topology, and in further research by scholars at home and abroad, the open winding topology was applied to induction motors, permanent magnet synchronous motors, double-fed motors and the like.

At present, home and abroad split winding brushless double-fed motors and control strategies thereof are less researched, and direct torque control, direct power control and the like of the split winding brushless double-fed motors are mainly adopted. According to the traditional open-winding brushless double-fed motor direct power control, the active power and the reactive power of a generator are fed back and compared with the given power to obtain power deviation, a voltage vector switch table is inquired by combining a sector where a control winding flux linkage is located, and a proper voltage vector is selected, so that the active power and the reactive power are controlled.

The traditional direct power control usually adopts a power hysteresis comparator, only has two control states, can not select a proper voltage vector according to the magnitude degree of a power error, and only needs to output a control signal in the loop width range of the hysteresis comparator regardless of the magnitude of deviation, thereby causing the fluctuation of power. If the method of reducing the loop width of the hysteresis comparator is adopted to achieve the purpose of reducing power fluctuation, the switching frequency of the voltage vector switch is greatly increased, the switching loss is increased, and the service life of the switch is shortened. Therefore, although the traditional direct power control of the open-winding brushless doubly-fed generator can basically meet the requirement of a control effect, certain problems still exist, such as the fact that active power and reactive power cannot be controlled within a hysteresis range, the current distortion of a control winding is serious, and the like.

Disclosure of Invention

In view of this, the present invention provides a method for direct power control of an open-winding brushless doubly-fed generator, which is used to overcome the shortcomings of the prior art.

The technical scheme of the invention is as follows:

a method for controlling direct power of an open-winding brushless doubly-fed generator comprises the following steps:

establishing a mathematical model for direct power control of the open-winding brushless doubly-fed generator;

designing an improved super-distortion sliding mode controller, and establishing an open-winding brushless doubly-fed generator direct power control mathematical model based on an improved super-distortion sliding mode;

performing stability analysis based on a Lyapunov function on an open-winding brushless doubly-fed generator direct power control mathematical model based on an improved super-distortion sliding mode, and acquiring a range of control model parameters;

and (3) randomly selecting a group of parameter combinations within the range of control model parameters to carry out simulation verification, finishing the design if the control precision meets the requirement of direct power control, and otherwise, revising the control model parameters until the control precision meets the design requirement, substituting the control model parameters meeting the requirement of direct power control into an open-winding brushless double-fed generator direct power control mathematical model based on an improved super-distortion sliding mode to obtain an accurate control model.

Preferably, the establishing of the mathematical model of the direct power control of the open-winding brushless doubly-fed generator comprises the following steps:

establishing a mathematical model of the open-winding brushless doubly-fed generator under a two-phase (d-q) rotating coordinate system, wherein the voltage and flux linkage equations are as follows:

wherein u is_dpAnd u_qpRespectively a d-axis voltage component and a q-axis voltage component i of a stator power winding under a d-q-axis rotating coordinate system_dpAnd i_qpD-axis and q-axis current components u under a d-q-axis rotating coordinate system of the power winding_dcAnd u_qcD-axis and q-axis voltage components, i, of a stator control winding in a d-q-axis rotating coordinate system_dcAnd i_qcD-axis and q-axis current components, psi, in a d-q-axis rotating coordinate system of the control winding_dpAnd psi_qpRespectively a d-axis flux linkage component and a q-axis flux linkage component psi under a d-q-axis rotating coordinate system of the stator power winding_dcAnd psi_qcRespectively are flux linkage components of a d axis and a q axis under a d-q axis rotating coordinate system of the control winding, Rp and Rc are respectively a power winding and a control winding resistor, Lp is a power winding self-inductance, Lc is a control winding self-inductance, Lm is a mutual inductance between the power winding and the control winding, omega is an angular velocity of the power winding in an arbitrary speed rotating reference coordinate system, and omega is an angular velocity of the power winding in an arbitrary speed rotating reference coordinate system_rD/dt is a differential operator for controlling the angular speed of the winding rotating reference coordinate system at any speed;

instantaneous active power P and reactive power Q output by a power winding of the open-winding brushless doubly-fed generator are defined based on an instantaneous power theory:

wherein P and Q are respectively the active power and the reactive power of the stator power winding, u_dpAnd u_qpD-axis and q-axis voltage components, i, in a d-q-axis rotating coordinate system of the power winding_dpAnd i_qpRespectively are d-axis current components and q-axis current components under a d-q-axis rotating coordinate system of the power winding;

will be at the synchronous speed omega_pRotating power winding reference axis system (d)_p-q_p) D of_pAxial orientation in power winding stator flux space vector psi_pIn the direction of phi at this time_dp＝ψ_p，ψ_qpWhen the value is 0, the relationship between the power winding current and the control winding flux linkage is derived from the formula (4):

wherein psi_qcFor controlling the q-component, psi, of the winding voltage in a d-q coordinate system_dcFor controlling the d-axis component, psi, of the winding voltage in a d-q-axis coordinate system_pIs the vector modulus, L, of the flux linkage of the power winding_pFor self-inductance of the power winding, L_cFor controlling the self-inductance of the winding, L_mFor mutual inductance between power winding and control winding, i_dpAnd i_qpRespectively are d-axis current components and q-axis current components under a d-q-axis rotating coordinate system of the power winding;

in the formula (6), u is substituted by the formula (7)_dp＝0，u_qp＝u_pThen, then

Wherein P and Q are respectively the active power and the reactive power of the stator power winding, u_pFor the vector norm value, psi, of the power winding voltage_pFor the flux linkage vector norm, psi, of the power winding_qcFor controlling the q-component, psi, of the winding voltage in a d-q coordinate system_dcFor controlling the d-axis component, L, of the winding voltage in a d-q-axis coordinate system_pFor self-inductance of the power winding, L_cFor controlling the self-inductance of the winding, L_mMutual inductance between the power winding and the control winding;

differentiating the time t, the derivative of the active and reactive power is expressed as:

and (3) converting the equation (9) into a space state to obtain a direct power control mathematical model of the open-winding brushless doubly-fed generator:

wherein P is the active power of the power winding, Q is the reactive power of the power winding, omega is the angular velocity of the power winding rotating at any speed in the reference coordinate system, omega_rFor controlling the angular velocity, u, of a reference frame of arbitrary-speed rotation of the windings_pFor the vector norm value, psi, of the power winding voltage_pIs the vector norm value of flux linkage of the power winding, u_qcFor controlling the q-component, u, of the winding voltage in a d-q coordinate system_dcFor controlling the d-axis component, L, of the winding voltage in a d-q-axis coordinate system_pFor self-inductance of the power winding, L_cFor controlling the self-inductance of the winding, L_mIs the mutual inductance between the power winding and the control winding.

Preferably, the method for establishing the direct power control mathematical model of the open-winding brushless doubly-fed generator based on the improved super-twisted sliding mode comprises the following steps:

selecting an instantaneous power error as a sliding mode surface, and defining a switching function:

wherein S is a sliding variable, S_PIs a sliding variable of the active power of the system power winding, i.e. the difference between the set value and the actual value of the active power, S_QAs a sliding variable of the reactive power of the power winding, i.e. the difference between the set value and the actual value of the reactive power, P^*，Q^*Are respectively asThe given values of the active power and the reactive power of the system power winding, P and Q are the actual values of the active power and the reactive power of the system power winding respectively;

constructing a Lyapunov function V:

the time derivation of the Lyapunov function is as follows:

wherein S is a sliding variable;

the slip variable of equation (12) is derived over time:

wherein S is_PIs a sliding variable of the active power of the system power winding, i.e. the difference between the set value and the actual value of the active power, S_QThe sliding variable of the reactive power of the power winding, namely the difference between a given value and an actual value of the reactive power, wherein P and Q are the active power and the reactive power of the stator power winding respectively;

substituting formula (1) into formula (15) to obtain the time derivative of the sliding mode surface as follows:

wherein the content of the first and second substances,

p is the active power of the power winding, Q is the reactive power of the power winding, u_pFor power winding voltage vector, #_pAs flux linkage vector, L, of the power winding_pFor self-inductance of the power winding, L_cTo control the self-inductance of the winding, L_mIs the mutual inductance between the power winding and the control winding, and omega isAngular velocity, omega, of a power winding rotating at any speed in a reference frame_rFor controlling the angular velocity, u, of a reference frame of arbitrary-speed rotation of the windings_qcFor controlling the q-component, u, of the winding voltage in a d-q coordinate system_dcIs D-axis component of control winding voltage in D-q-axis coordinate system, U is control winding voltage matrix, D is coefficient matrix, F₁And F₂Is a known term in the direct power control equation;

in order to ensure that dV/dt is less than 0, the improved supertorsion sliding mode control law is designed as follows:

where U is the control winding voltage matrix, D is the coefficient matrix, F₁And F₂As a known term in the direct power control equation, a₁、a₂、b₁、b₂Are the observer gain, S_PIs a sliding variable of the active power of the system power winding, i.e. the difference between the set value and the actual value of the active power, S_QThe sliding variable of the reactive power of the power winding, namely the difference between the given value and the actual value of the reactive power, is an adjusting coefficient.

Preferably, the stability analysis based on the Lyapunov function comprises the following steps:

stability analysis based on Lyapunov function:

substituting the formulas (16) and (2) into the formula (14):

wherein a1, a2, b1 and b2 are observer gains, S_PIs a sliding variable of the active power of the system power winding, i.e. the difference between the set value and the actual value of the active power, S_QThe sliding variable of the reactive power of the power winding, namely the difference between a given value and an actual value of the reactive power, is an adjusting coefficient;

judging whether dV/dt is less than 0, if dV/dt is less than 0, the function is negative definite function, and if dV/dt is greater than 0, the function is positive definite function;

when dV/dt<0, the system meets the Lyapunov gradual stabilization condition, S_P、S_QGradually approaching zero.

Compared with the prior art, the method for controlling the direct power of the open-winding brushless doubly-fed generator realizes decoupling control of active power and reactive power by establishing a relational equation between voltage at the control winding side and active power and reactive power at the power winding side, has a simple control structure and a flexible mode, and improves the reaction speed of a system; the control method improves the improved supertorsion sliding mode control approach law and effectively reduces the buffeting phenomenon in the sliding mode control; the whole control system overcomes the defects of unfixed frequency, serious distortion of control current, large static difference and the like of the traditional direct power control, can realize the real-time stable tracking control of power, has high control precision, small overshoot and high response speed, has good dynamic and static performances and higher robustness, is suitable for a variable-speed constant-frequency power generation system, has good practicability and is worthy of popularization.

Drawings

FIG. 1 is a flow chart of the present invention;

FIG. 2 is a variable speed constant frequency wind power generation system of the OW-BDFG of the present invention;

FIG. 3 is a power winding flux linkage orientation vector space relationship diagram of the present invention;

FIG. 4 is a graph of the tan h function and sgn function of the present invention;

FIG. 5 is a block diagram of an OW-BDFG direct power control system based on an improved super-twisted sliding mode according to the invention;

fig. 6 is a simulation waveform of the improved super-twisted sliding mode control part under the constant rotating speed and power conditions of the invention, wherein (a) active power (b) reactive power (c) power winding current (d) controls winding current.

Detailed Description

The invention provides a method for controlling direct power of an open-winding brushless doubly-fed generator, and the invention is described below with reference to schematic diagrams of fig. 1 to 6.