Torque control method for full-power conversion wind power generation system

Abstract

The invention relates to the technical field of wind power generation, in particular to a torque control method for a full-power conversion wind power generation system, which comprises the following steps of: presetting an optimal torque characteristic curve of a wind turbine at different wind speeds, and acquiring a current rotating speed value of the wind turbine in real time; searching from an optimal torque characteristic curve of the wind turbine to obtain an optimal output torque corresponding to the acquired rotating speed value; the electromagnetic torque of the generator is calculated in real time; and constructing a mathematical model between the torque error of the generator and the PID regulator parameters, carrying out iteration on the PID regulator parameters based on a particle swarm algorithm, outputting the optimal PID regulator parameters, and adjusting the electromagnetic torque of the generator through the optimal PID regulator parameters. According to the torque control method for the full-power conversion wind power generation system, the optimal torque characteristic curve is preset, the electromagnetic torque is calculated in real time, PID parameters are optimized based on the particle swarm optimization, and efficient and accurate torque control of the wind power generation system is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a full-power conversion wind power generation system. Background Art

[0002] Wind power generation technology is the process of using wind energy to drive wind turbines and converting mechanical energy into electrical energy through the principle of electromagnetic induction. Full-power conversion wind power generation systems can achieve efficient energy conversion at different wind speeds. In order to improve the operating efficiency and stability of wind power generation systems, the application of torque control methods in wind power generation systems is particularly important. In the prior art, methods based on PID controllers have been widely used, but their parameter adjustment is relatively complex and it is difficult to achieve the optimal control effect. Therefore, it is of great significance to propose a torque control method for full-power conversion wind power generation systems that can optimize PID parameters in real time. Summary of the invention

[0003] In order to solve the problems in the above-mentioned background technology, the purpose of the present invention is to provide a torque control method for a full-power conversion wind power generation system, which realizes efficient and accurate torque control of the wind power generation system by presetting the optimal torque characteristic curve, calculating the electromagnetic torque in real time, and optimizing PID parameters based on the particle swarm algorithm.

[0004] The present invention adopts the following technical solutions:

[0005] A torque control method for a full power conversion wind power generation system, the method comprising:

[0006] S1: Preset the optimal torque characteristic curve of the wind turbine at different wind speeds and collect the current speed value of the wind turbine in real time;

[0007] S2: Finding the optimal output torque corresponding to the collected rotational speed value from the optimal torque characteristic curve of the wind turbine, and using the optimal output torque as the target value for controlling the generator torque;

[0008] S3: establishing a mathematical model of the speed value of the wind turbine and the electromagnetic torque of the generator, and performing real-time calculation of the electromagnetic torque of the generator;

[0009] S4: Construct an electromagnetic torque control loop of the generator based on the PID regulator, construct a mathematical model between the torque error of the generator and the PID regulator parameters, iterate the PID regulator parameters based on the particle swarm algorithm and output the optimal PID regulator parameters, and adjust the electromagnetic torque of the generator through the optimal PID regulator parameters.

[0010] Furthermore, the speed value is related to the electromagnetic torque T of the generator. e The mathematical model is:

[0011]

[0012] The mechanical power P of the wind turbine r The mathematical model is:

[0013] P r =T e ·ω r ;

[0014] Where, ρ represents the air density, R represents the radius of the fan, v represents the speed of the wind turbine, Cp represents the power coefficient of the fan, ω r Indicates the speed of the generator.

[0015] Furthermore, the target torque characteristic curve T is set ref (t), used to represent the torque value expected at a given point in time;

[0016] The mathematical model between the torque error of the generator and the PID regulator parameters is:

[0017]

[0018] Where, e(t) = T ref (t)-T actual (t), represents the torque error, T actual (t) represents the actual torque of the generator, K p Represents the proportionality coefficient, K i Indicates the integral coefficient, K d represents the differential coefficient.

[0019] Furthermore, the method for iterating PID regulator parameters based on particle swarm algorithm and outputting optimal PID regulator parameters includes designing a fitness function for evaluating the performance of PID parameter combination, which is used to minimize the torque error, and the error indicators include the integrated square error ISE, the integrated time absolute error ITAE and the integrated absolute error IOAE,

[0020] The fitness function is expressed as:

[0021] f(K p ,K i ,K d )=α·ISE+β·ITAE+γ·IOAE;

[0022] in, α, β and γ represent weight coefficients for balancing different error types; initialize a particle swarm, each particle in the particle swarm represents a PID parameter combination, initialize the particle speed to adjust its position, define the search range of the PID parameter, and calculate the value of the fitness function for each particle PID parameter combination; set the maximum number of iterations and the accuracy of the fitness function, update the particle position and speed and iterate, stop the iteration when the maximum number of iterations is reached or the accuracy of the fitness function is met, and output the position and fitness value of the optimal particle.

[0023] Furthermore, the function for updating the particle position is:

[0024] x i (t+1)=x i (t)+v i (t+1);

[0025] The function of the update particle speed is:

[0026] v i (t+1)=ω·v i (t)+c1·r1 / (p best,i -x i (t))+c2 / r2·(g best -x i (t));

[0027] Among them, ω is the inertia weight, c1 and c2 are learning factors, r1 and r2 are random numbers, and p best,i is the best historical position of particle i, g best is the global optimal position, x i represents the current position of the particle, v i Indicates the current speed of the particle.

[0028] Furthermore, the search range of the PID parameters is set to, K p ∈[0,10], K i ∈[0,1],K d ∈[0,5].

[0029] A full power conversion wind power generation system, the system adopts the above torque control method.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] A full-power conversion wind power generation system of the present invention constructs a mathematical model between the torque error of the generator and the PID regulator parameters, iterates the PID regulator parameters based on the particle swarm algorithm and outputs the optimal PID regulator parameters, and adjusts the electromagnetic torque of the generator through the optimal PID regulator parameters, so that the actual speed of the wind turbine gradually approaches the target speed. By controlling the speed of the wind turbine, it can be made to work at the optimal efficiency point under different wind speed conditions, thereby achieving maximum power output. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 The invention discloses a torque control method for a full-power conversion wind power generation system. DETAILED DESCRIPTION

[0034] The following will be combined with the accompanying drawings in 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 belong to the protection scope of the present invention.

[0035] The following will be combined with the accompanying drawings in 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 belong to the protection scope of the present invention.

[0036] Specifically, Figure 1 A torque control method for a full power conversion wind power generation system is shown, the method comprising:

[0037] S1: Preset the optimal torque characteristic curve of the wind turbine at different wind speeds, collect the current wind turbine speed value in real time; measure the wind turbine speed in real time through the speed sensor, and feed the acquired speed signal back to the control system

[0038] S2: finding the optimal output torque corresponding to the collected speed value from the optimal torque characteristic curve of the wind turbine, and using the optimal output torque as the target value for controlling the generator torque; the optimal torque characteristic curve is obtained by calculating a predetermined power curve or an empirical formula;

[0039] S3: Establishing a mathematical model of the rotation speed of the wind turbine and the electromagnetic torque of the generator, and performing real-time calculation of the electromagnetic torque of the generator; there is a certain relationship between the output power of the wind turbine and the rotation speed.

[0040] S4: Construct the electromagnetic torque control loop of the generator based on the PID regulator, construct the mathematical model between the torque error of the generator and the PID regulator parameters, iterate the PID regulator parameters based on the particle swarm algorithm and output the optimal PID regulator parameters, and adjust the electromagnetic torque of the generator through the optimal PID regulator parameters. The PID regulator adjusts the excitation current or other control parameters of the generator to change the electromagnetic torque of the generator, thereby adjusting the speed of the wind turbine; continuously monitor the output power of the wind turbine to ensure that the system works near the maximum power point. If the output power drops, adjust the speed of the wind turbine, and generate the optimal PID adjustment parameters at the same time to re-optimize the power output. As a result, the actual speed of the wind turbine gradually approaches the target speed. By controlling the speed of the wind turbine, it can work at the optimal efficiency point under different wind speed conditions, thereby achieving maximum power output.

[0041] Specifically, the speed value is related to the electromagnetic torque T of the generator. e The mathematical model is:

[0042]

[0043] The mechanical power P of the wind turbine r The mathematical model is:

[0044] P r =T e ·ω r ;

[0045] Where, ρ represents the air density, R represents the radius of the fan, v represents the speed of the wind turbine, Cp represents the power coefficient of the fan, ω r Indicates the speed of the generator.

[0046] Specifically, the target torque characteristic curve T is set ref (t), used to represent the torque value expected at a given point in time;

[0047] The mathematical model between the torque error of the generator and the PID regulator parameters is:

[0048]

[0049] Where, e(t) = T ref (t)-T actual (t), represents the torque error, T actual (t) represents the actual torque of the generator, K p Represents the proportionality coefficient, K i Indicates the integral coefficient, K d represents the differential coefficient.

[0050] Specifically, the method for iterating PID regulator parameters based on particle swarm algorithm and outputting optimal PID regulator parameters includes designing a fitness function for evaluating the performance of PID parameter combination, which is used to minimize the torque error, and the error indicators include the integrated square error ISE, the integrated time absolute error ITAE and the integrated absolute error IOAE,

[0051] The fitness function is expressed as:

[0052] f(K p ,K i ,K d )=α·ISE+β·ITAE+γ·IOAE;

[0053] in, α, β and γ represent weight coefficients for balancing different error types; initialize a particle swarm, each particle in the particle swarm represents a PID parameter combination, initialize the particle speed to adjust its position, define the search range of the PID parameter, and calculate the value of the fitness function for each particle PID parameter combination; set the maximum number of iterations and the accuracy of the fitness function, update the particle position and speed and iterate, stop the iteration when the maximum number of iterations is reached or the accuracy of the fitness function is met, and output the position and fitness value of the optimal particle.

[0054] Specifically, the function for updating the particle position is:

[0055] x i (t+1)=x i (t)+v i (t+1);

[0056] The function of the update particle speed is:

[0057] v i (t+1)=ω·v i (t)+c1·r1·(p best,i -x i (t))+c2·r2·(g best -x i (t));

[0058] Among them, ω is the inertia weight, c1 and c2 are learning factors, r1 and r2 are random numbers, and p best,i is the best historical position of particle i, g best is the global optimal position, x i represents the current position of the particle, v i Indicates the current speed of the particle.

[0059] Specifically, the search range of the PID parameters is set to, K p ∈[0,10], K i ∈[0,1],K d ∈[0,5].

[0060] A full-power conversion wind power generation system, the system uses the above-mentioned torque control method; the output electric energy of the wind turbine generator is converted into electric energy compatible with the power grid through a full-power converter, and has high control flexibility and efficiency. The system can not only effectively control the output power and frequency of the generator, but also realize the complete decoupling of the generator and the power grid, and provide more stable power output. The system includes a wind turbine, a generator, a full-power converter, and a control system. The wind turbine is responsible for converting wind energy into mechanical energy, and then the generator converts the mechanical energy into electric energy; the full-power converter includes a rectifier, a DC link and an inverter, which is responsible for converting the electric energy output by the generator into electric energy that meets the requirements of the power grid. The rectifier is used to convert the alternating current output by the generator into direct current, the DC link is used to store energy and smooth the direct current, and the inverter is used to convert the direct current into alternating current synchronized with the power grid. The control system is responsible for real-time monitoring and control of the operating status of the wind turbine generator and the full-power converter. The control system includes a wind speed measurement module, a torque control module and a PID parameter optimization module, which are used for.

[0061] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0062] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0063] The present invention is further described above with the aid of specific embodiments. However, it should be understood that the specific description here should not be construed as limiting the essence and scope of the present invention. Various modifications made to the above embodiments by ordinary technicians in the field after reading this specification are all within the scope of protection of the present invention.

Claims

1. A torque control method for a full power conversion wind power generation system, characterized in that: The method comprises: S1: Preset the optimal torque characteristic curve of the wind turbine at different wind speeds and collect the current speed value of the wind turbine in real time; S2: Finding the optimal output torque corresponding to the collected rotational speed value from the optimal torque characteristic curve of the wind turbine, and using the optimal output torque as the target value for controlling the generator torque; S3: establishing a mathematical model of the speed value of the wind turbine and the electromagnetic torque of the generator, and performing real-time calculation of the electromagnetic torque of the generator; S4: Construct an electromagnetic torque control loop of the generator based on the PID regulator, construct a mathematical model between the torque error of the generator and the PID regulator parameters, iterate the PID regulator parameters based on the particle swarm algorithm and output the optimal PID regulator parameters, and adjust the electromagnetic torque of the generator through the optimal PID regulator parameters.

2. A torque control method for a full power conversion wind power generation system according to claim 1, characterized in that: The speed value is related to the electromagnetic torque T of the generator. e The mathematical model is: The mechanical power P of the wind turbine r The mathematical model is: P r =T e ·oh r ; Where, ρ represents the air density, R represents the radius of the fan, v represents the speed of the wind turbine, Cp represents the power coefficient of the fan, ω r Indicates the speed of the generator.

3. A torque control method for a full power conversion wind power generation system according to claim 1, characterized in that: Set the target torque characteristic curve T ref (t), used to represent the expected torque value at a given time point; the mathematical model between the torque error of the generator and the PID regulator parameters is: Where, e(t) = T ref (t)-T actual (t), represents the torque error, T actual (t) represents the actual torque of the generator, K p Represents the proportionality coefficient, K i Indicates the integral coefficient, K d represents the differential coefficient.

4. A torque control method for a full power conversion wind power generation system according to claim 3, characterized in that: The method for iterating PID regulator parameters based on particle swarm algorithm and outputting optimal PID regulator parameters includes designing a fitness function for evaluating the performance of PID parameter combination, which is used to minimize torque error, and the error indicators include integrated square error ISE, integrated time absolute error ITAE and integrated absolute error IOAE, The fitness function is expressed as: f(K p ,K i ,K d )=α·ISE+β·ITAE+γ·IOAE; in, α, β and γ represent weight coefficients for balancing different error types; initialize a particle swarm, each particle in the particle swarm represents a PID parameter combination, initialize the particle speed to adjust its position, define the search range of the PID parameter, and calculate the value of the fitness function for each particle PID parameter combination; set the maximum number of iterations and the accuracy of the fitness function, update the particle position and speed and iterate, stop the iteration when the maximum number of iterations is reached or the accuracy of the fitness function is met, and output the position and fitness value of the optimal particle.

5. A full power conversion wind power generation system according to claim 4, characterized in that: The function for updating the particle position is: x i (t+1)=x i (t)+v i (t+1); The function of the update particle speed is: v i (t+1)=ω·v i (t)+c1·r1·(p best,i -x i (t))+c2·r2·(g best -x i (t)); Among them, ω is the inertia weight, c1 and c2 are learning factors, r1 and r2 are random numbers, and p best,i is the best historical position of particle i, g best is the global optimal position, x i represents the current position of the particle, v i Indicates the current speed of the particle.

6. A torque control method for a full power conversion wind power generation system according to claim 5, characterized in that: The search range of the PID parameters is set to, K p ∈[0,10], K i ∈[0,1],K d ∈[0,5].

7. A full power conversion wind power generation system, characterized in that: The system uses the torque control method described in any one of claims 1-6.

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