Method and device for controlling grid-forming type fan grid-connected system

Abstract

The invention relates to the technical field of new energy grid connection, and particularly provides a control method and device for a grid-forming type fan grid-connected system, and the method comprises the steps: collecting the frequency variation of a grid-connected point and the power of the grid-connected point in the grid-forming type fan grid-connected system; generating a PWM (Pulse Width Modulation) signal used for controlling a machine-side converter in the grid-connected system of the constructed fan on the basis of the frequency variation of the grid-connected point; and generating a PWM (Pulse Width Modulation) signal for controlling a grid-side converter in the grid-forming type fan grid-connected system based on the grid-connected point power. According to the technical scheme provided by the invention, the frequency negative feedback of the wind turbine generator access power grid point is introduced, the rotating speed of the fan system is controlled in real time, and the kinetic energy of the fan system is associated with the active power fluctuation of the wind turbine generator access point through the converter, so that the system frequency fluctuation problem of the wind turbine generator and even a wind power plant grid-connected point is solved; the system stability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy grid-connected technology, and in particular to a control method and device for a grid-connected wind turbine system. Background Art

[0002] Frequency is an important power quality indicator of the power system, and the magnitude of frequency deviation is related to the safe and stable operation of the power grid. The system frequency depends on the balance of active power. When the active power supply is insufficient, the frequency decreases, and when the active power supply is excessive, the frequency increases. The load is constantly changing, so it is necessary to continuously adjust the active power supply of wind turbines to maintain the dynamic balance of the system frequency.

[0003] Wind turbines are connected to the grid for power generation through power electronic converters, which realizes the decoupling control of the unit speed and the grid frequency, but lacks fast frequency response and active support capabilities. Currently, wind turbines are all running at the maximum power point, and the converter does not directly control the generator speed. Therefore, when the grid-connected system frequency rises / falls, it is impossible to quickly provide active frequency support within ms. As the proportion of wind power generation in the grid continues to increase, the inertia level of the system is gradually decreasing. Therefore, it is very necessary for wind turbines and even wind farms to participate in the research on the inertia support capability of grid frequency response. Summary of the invention

[0004] In order to overcome the above-mentioned defects, the present invention proposes a control method and device for a grid-connected wind turbine system.

[0005] In a first aspect, a control method for a grid-connected wind turbine system is provided, the control method for a grid-connected wind turbine system comprising:

[0006] Collect the frequency change and power of the grid connection point in the grid-connected wind turbine system;

[0007] Generate a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the grid-connected point frequency variation;

[0008] A PWM signal for controlling a grid-side converter in a grid-connected wind turbine system is generated based on the grid-connected point power.

[0009] Preferably, the generating of a PWM signal for controlling a machine-side converter in a grid-connected wind turbine grid-connected system based on the grid-connected point frequency variation comprises:

[0010] Generate a speed reference value based on the frequency change of the grid connection point;

[0011] A PWM signal for controlling a machine-side converter in a grid-connected wind turbine system is generated based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value.

[0012] Furthermore, the calculation formula of the speed reference value is as follows:

[0013] ω ref =2π(50±△f)

[0014] In the above formula, ω ref is the speed reference value, △f is the frequency change of the grid connection point.

[0015] Furthermore, the method of generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value includes:

[0016] The electromagnetic torque of the permanent magnet synchronous generator is compared with the electromagnetic torque reference value of the permanent magnet synchronous generator and then integrated to obtain the rotation speed of the permanent magnet synchronous generator;

[0017] The rotation speed of the permanent magnet synchronous generator is compared with a rotation speed reference value and then passed through a PI controller to obtain a q-axis current component;

[0018] The d-axis current component and the q-axis current component are transformed by inverse Park to obtain a three-phase current reference value;

[0019] The three-phase current sampling value is compared with the three-phase current reference value to obtain a first three-phase reference voltage through a differential controller;

[0020] The first three-phase reference voltage is obtained through a PWM power drive module to obtain a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system;

[0021] The coordinate angle required for the Park inverse transformation is the rotor angular displacement of the permanent magnet synchronous generator, and the d-axis current component is equal to 0.

[0022] Furthermore, the calculation formula of the electromagnetic torque reference value of the permanent magnet synchronous generator is as follows:

[0023]

[0024] In the above formula, T m_ref is the electromagnetic torque reference value of the permanent magnet synchronous generator, J is the moment of inertia, ω is the speed of the wind turbine mechanical shaft system, t is the time, T e is the electromagnetic torque of the permanent magnet synchronous generator.

[0025] Furthermore, the calculation formula of the first three-phase reference voltage is as follows:

[0026]

[0027] In the above formula, u abc_ref is the first three-phase reference voltage, L mis the equivalent inductance at the fan outlet, △i abc is the difference between the three-phase current reference value and the three-phase current sampling value, △t is the control period, i abc_ref is the three-phase current reference value, i abc is the three-phase current sampling value, and t is the time.

[0028] Preferably, the generating of a PWM signal for controlling a grid-side converter in a grid-connected wind turbine system based on the grid-connected point power comprises:

[0029] The DC voltage of the grid-side converter is compared with the DC voltage reference value after passing through a low-pass filter to obtain a DC voltage difference;

[0030] The DC voltage difference is passed through a PI controller to obtain a power reference value;

[0031] Compare the grid connection point power with the power reference value after passing through a low-pass filter to obtain a power difference;

[0032] The power difference is passed through a PI controller to obtain an initial phase angle;

[0033] The initial phase angle is used to generate a second three-phase reference voltage via a reference wave generator;

[0034] The second three-phase reference voltage is passed through a PWM power drive module to obtain a PWM signal for controlling a grid-side converter in a grid-connected wind turbine system.

[0035] Furthermore, the calculation formula of the second three-phase reference voltage is as follows:

[0036]

[0037] In the above formula, u a_ref 、u b_ref 、u c_ref are the a, b, and c phase voltages of the second three-phase reference voltage, U m is the given voltage amplitude, f is the given frequency, t is the time, is the initial phase angle.

[0038] In a second aspect, a grid-connected wind turbine system control device is provided, the grid-connected wind turbine system control device comprising:

[0039] The acquisition module is used to collect the frequency change and power of the grid connection point in the grid-connected wind turbine system;

[0040] A machine-side converter control module, used for generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the frequency variation of the grid-connected point;

[0041] The grid-side converter control module is used to generate a PWM signal for controlling the grid-side converter in the grid-connected wind turbine system based on the grid-connected point power.

[0042] Preferably, the machine-side converter control module is specifically used for:

[0043] Generate a speed reference value based on the frequency change of the grid connection point;

[0044] A PWM signal for controlling a machine-side converter in a grid-connected wind turbine system is generated based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value.

[0045] Furthermore, the calculation formula of the speed reference value is as follows:

[0046] ω ref =2π(50±△f)

[0047] In the above formula, ω ref is the speed reference value, △f is the frequency change of the grid connection point.

[0048] Furthermore, the method of generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value includes:

[0049] The electromagnetic torque of the permanent magnet synchronous generator is compared with the electromagnetic torque reference value of the permanent magnet synchronous generator and then integrated to obtain the rotation speed of the permanent magnet synchronous generator;

[0050] The rotation speed of the permanent magnet synchronous generator is compared with a rotation speed reference value and then passed through a PI controller to obtain a q-axis current component;

[0051] The d-axis current component and the q-axis current component are transformed by inverse Park to obtain a three-phase current reference value;

[0052] The three-phase current sampling value is compared with the three-phase current reference value to obtain a first three-phase reference voltage through a differential controller;

[0053] The first three-phase reference voltage is obtained through a PWM power drive module to obtain a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system;

[0054] The coordinate angle required for the Park inverse transformation is the rotor angular displacement of the permanent magnet synchronous generator, and the d-axis current component is equal to 0.

[0055] Furthermore, the calculation formula of the electromagnetic torque reference value of the permanent magnet synchronous generator is as follows:

[0056]

[0057] In the above formula, T m_ref is the electromagnetic torque reference value of the permanent magnet synchronous generator, J is the moment of inertia, ω is the speed of the wind turbine mechanical shaft system, t is the time, T e is the electromagnetic torque of the permanent magnet synchronous generator.

[0058] Furthermore, the calculation formula of the first three-phase reference voltage is as follows:

[0059]

[0060] In the above formula, u abc_ref is the first three-phase reference voltage, L m is the equivalent inductance at the fan outlet, △i abc is the difference between the three-phase current reference value and the three-phase current sampling value, △t is the control period, i abc_ref is the three-phase current reference value, i abc is the three-phase current sampling value, and t is the time.

[0061] Preferably, the grid-side converter control module is specifically used for:

[0062] The DC voltage of the grid-side converter is compared with the DC voltage reference value after passing through a low-pass filter to obtain a DC voltage difference;

[0063] The DC voltage difference is passed through a PI controller to obtain a power reference value;

[0064] Compare the grid connection point power with the power reference value after passing through a low-pass filter to obtain a power difference;

[0065] The power difference is passed through a PI controller to obtain an initial phase angle;

[0066] The initial phase angle is used to generate a second three-phase reference voltage via a reference wave generator;

[0067] The second three-phase reference voltage is passed through a PWM power drive module to obtain a PWM signal for controlling a grid-side converter in a grid-connected wind turbine system.

[0068] Furthermore, the calculation formula of the second three-phase reference voltage is as follows:

[0069]

[0070] In the above formula, u a_ref 、u b_ref 、u c_ref are the a, b, and c phase voltages of the second three-phase reference voltage, U m is the given voltage amplitude, f is the given frequency, t is the time, is the initial phase angle.

[0071] In a third aspect, a computer device is provided, comprising: one or more processors;

[0072] The processor is configured to execute one or more programs;

[0073] When the one or more programs are executed by the one or more processors, the grid-connected wind turbine system control method is implemented.

[0074] In a fourth aspect, a computer-readable storage device is provided, on which a computer program is stored, and when the computer program is executed, the control method of the grid-connected wind turbine system is implemented.

[0075] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0076] The present invention provides a control method and device for a grid-connected wind turbine grid-connected system, the method comprising: collecting the frequency change amount and the power of the grid-connected point in the grid-connected wind turbine grid-connected system; generating a PWM signal for controlling the machine-side converter of the grid-connected wind turbine grid-connected system based on the frequency change amount; generating a PWM signal for controlling the grid-side converter of the grid-connected wind turbine grid-connected system based on the power of the grid-connected point. The technical solution provided by the present invention adjusts the control signals of the machine-side converter and the grid-side converter of the grid-connected wind turbine grid-connected system by continuously following the frequency change amount and the power of the grid-connected point, so as to maintain the dynamic balance of the system frequency and improve the system stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 1. It is a schematic flow chart of the main steps of the control method of the grid-connected wind turbine system according to an embodiment of the present invention;

[0078] Figure 2 This is a block diagram of a grid-connected wind turbine system according to an embodiment of the present invention;

[0079] Figure 3 is a structural block diagram of a machine-side converter controller according to an embodiment of the present invention;

[0080] Figure 4 It is a structural block diagram of a grid-side converter controller according to an embodiment of the present invention. DETAILED DESCRIPTION

[0081] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0082] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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. 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.

[0083] As disclosed in the background technology, frequency is an important power quality indicator of the power system, and the magnitude of frequency deviation is related to the safe and stable operation of the power grid. The system frequency depends on the balance of active power. When the active power supply is insufficient, the frequency decreases, and when the active power supply is excessive, the frequency increases. The load is constantly changing, so it is necessary to continuously follow and adjust the active power supply of the wind turbine to maintain the dynamic balance of the system frequency.

[0084] Wind turbines are connected to the grid for power generation through power electronic converters, which realizes the decoupling control of the unit speed and the grid frequency, but lacks fast frequency response and active support capabilities. Currently, wind turbines are all running at the maximum power point, and the converter does not directly control the generator speed. Therefore, when the grid-connected system frequency rises / falls, it is impossible to quickly provide active frequency support within ms. As the proportion of wind power generation in the grid continues to increase, the inertia level of the system is gradually decreasing. Therefore, it is very necessary for wind turbines and even wind farms to participate in the research on the inertia support capability of grid frequency response.

[0085] In order to improve the above problems, the present invention provides a control method and device for a grid-connected wind turbine grid-connected system, the method comprising: collecting the frequency change of the grid-connected point and the power of the grid-connected point in the grid-connected wind turbine grid-connected system; generating a PWM signal for controlling the machine-side converter of the grid-connected wind turbine grid-connected system based on the frequency change of the grid-connected point; generating a PWM signal for controlling the grid-side converter of the grid-connected wind turbine grid-connected system based on the power of the grid-connected point. The technical solution provided by the present invention adjusts the control signals of the machine-side converter and the grid-side converter of the grid-connected wind turbine grid-connected system by continuously following the frequency change of the grid-connected point and the power of the grid-connected point, so as to maintain the dynamic balance of the system frequency and improve the system stability.

[0086] The above scheme is described in detail below.

[0087] Example 1

[0088] See attached Figure 1 , Figure 1 FIG. 1 is a flow chart showing the main steps of a method for controlling a grid-connected wind turbine system according to an embodiment of the present invention. Figure 1 As shown, the control method of the grid-connected wind turbine system in the embodiment of the present invention mainly includes the following steps:

[0089] Step S101: collecting the frequency change and power of the grid connection point in the grid-connected wind turbine system;

[0090] Step S102: generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the grid-connected point frequency variation;

[0091] Step S103: generating a PWM signal for controlling a grid-side converter in a grid-connected wind turbine system based on the grid-connected point power.

[0092] In one embodiment, the grid-connected wind turbine system is as follows: Figure 2 shown.

[0093] In this embodiment, the method of generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the grid-connected point frequency variation includes:

[0094] Generate a speed reference value based on the frequency change of the grid connection point;

[0095] A PWM signal for controlling a machine-side converter in a grid-connected wind turbine system is generated based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value.

[0096] In one embodiment, the speed reference value is calculated by the fan main controller, and the specific calculation formula is as follows:

[0097] ω ref =2π(50±△f)

[0098] In the above formula, ω ref is the speed reference value, △f is the frequency change of the grid connection point.

[0099] In one embodiment, if Figure 3 As shown, the PWM signal for controlling the machine-side converter in the grid-connected wind turbine system based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value is generated by the machine-side converter controller, and includes:

[0100] Compare the electromagnetic torque of the permanent magnet synchronous generator with the electromagnetic torque reference value of the permanent magnet synchronous generator and integrate them to get the speed ω of the permanent magnet synchronous generator. m ;

[0101] The speed of the permanent magnet synchronous generator is compared with the speed reference value and then passed through the PI controller to obtain the q-axis current component i q ;

[0102] The d-axis current component i d and the q-axis current component i qThe three-phase current reference value i is obtained by inverse Park transformation abc_ref ;

[0103] The three-phase current sampling value i abc and the three-phase current reference value i abc_ref After comparison, the first three-phase reference voltage u is obtained through the differential controller abc_ref ;

[0104] The first three-phase reference voltage is obtained through a PWM power drive module to obtain a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system;

[0105] The coordinate angle required for the Park inverse transformation is the rotor angular displacement θ of the permanent magnet synchronous generator. r , the d-axis current component is equal to 0.

[0106] In one embodiment, the electromagnetic torque reference value of the permanent magnet synchronous generator is calculated by the wind turbine main controller, and the specific calculation formula is as follows:

[0107]

[0108] In the above formula, T m_ref is the electromagnetic torque reference value of the permanent magnet synchronous generator, J is the moment of inertia, ω is the speed of the wind turbine mechanical shaft system, t is the time, T e is the electromagnetic torque of the permanent magnet synchronous generator.

[0109] In one embodiment, the calculation formula of the first three-phase reference voltage is as follows:

[0110]

[0111] In the above formula, u abc_ref is the first three-phase reference voltage, L m is the equivalent inductance at the fan outlet, △i abc is the difference between the three-phase current reference value and the three-phase current sampling value, △t is the control period, i abc_ref is the three-phase current reference value, i abc is the three-phase current sampling value, and t is the time.

[0112] In this embodiment, Figure 4 As shown, the PWM signal for controlling the grid-side converter in the grid-connected wind turbine grid-connected system based on the grid-connected point power is generated by a grid-side converter controller, and specifically includes:

[0113] The DC voltage U dc After passing through the low-pass filter, it is compared with the DC voltage reference value U dc_ref By comparison, we get the DC voltage difference △U dc ;

[0114] The DC voltage difference is passed through a PI controller to obtain a power reference value P ref ;

[0115] The grid-connected point power P pcc After passing through a low-pass filter, the power is compared with the power reference value to obtain a power difference △P;

[0116] The power difference is passed through a PI controller to obtain an initial phase angle;

[0117] The initial phase angle is used to generate a second three-phase reference voltage via a reference wave generator;

[0118] The second three-phase reference voltage is passed through a PWM power drive module to obtain a PWM signal for controlling a grid-side converter in a grid-connected wind turbine system.

[0119] In one embodiment, the second three-phase reference voltage is calculated as follows:

[0120]

[0121] In the above formula, u a_ref 、u b_ref 、u c_ref are the a, b, and c phase voltages of the second three-phase reference voltage, U m is the given voltage amplitude, f is the given frequency, t is the time, is the initial phase angle.

[0122] Example 2

[0123] Based on the same inventive concept, the present invention also provides a grid-connected wind turbine grid-connected system control device, the grid-connected wind turbine grid-connected system control device comprising:

[0124] The acquisition module is used to collect the frequency change and power of the grid connection point in the grid-connected wind turbine system;

[0125] A machine-side converter control module, used for generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the frequency variation of the grid-connected point;

[0126] The grid-side converter control module is used to generate a PWM signal for controlling the grid-side converter in the grid-connected wind turbine system based on the grid-connected point power.

[0127] Preferably, the machine-side converter control module is specifically used for:

[0128] Generate a speed reference value based on the frequency change of the grid connection point;

[0129] A PWM signal for controlling a machine-side converter in a grid-connected wind turbine system is generated based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value.

[0130] Furthermore, the calculation formula of the speed reference value is as follows:

[0131] ω ref =2π(50±△f)

[0132] In the above formula, ω ref is the speed reference value, △f is the frequency change of the grid connection point.

[0133] Further, the method of generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value includes:

[0134] The electromagnetic torque of the permanent magnet synchronous generator is compared with the electromagnetic torque reference value of the permanent magnet synchronous generator and then integrated to obtain the rotation speed of the permanent magnet synchronous generator;

[0135] The rotation speed of the permanent magnet synchronous generator is compared with a rotation speed reference value and then passed through a PI controller to obtain a q-axis current component;

[0136] The d-axis current component and the q-axis current component are transformed by inverse Park to obtain a three-phase current reference value;

[0137] The three-phase current sampling value is compared with the three-phase current reference value to obtain a first three-phase reference voltage through a differential controller;

[0138] The first three-phase reference voltage is obtained through a PWM power drive module to obtain a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system;

[0139] The coordinate angle required for the Park inverse transformation is the rotor angular displacement of the permanent magnet synchronous generator, and the d-axis current component is equal to 0.

[0140] Furthermore, the calculation formula of the electromagnetic torque reference value of the permanent magnet synchronous generator is as follows:

[0141]

[0142] In the above formula, T m_ref is the electromagnetic torque reference value of the permanent magnet synchronous generator, J is the moment of inertia, ω is the speed of the wind turbine mechanical shaft system, t is the time, T e is the electromagnetic torque of the permanent magnet synchronous generator.

[0143] Furthermore, the calculation formula of the first three-phase reference voltage is as follows:

[0144]

[0145] In the above formula, u abc_ref is the first three-phase reference voltage, L m is the equivalent inductance at the fan outlet, △i abc is the difference between the three-phase current reference value and the three-phase current sampling value, △t is the control period, i abc_ref is the three-phase current reference value, i abc is the three-phase current sampling value, and t is the time.

[0146] Preferably, the grid-side converter control module is specifically used for:

[0147] The DC voltage of the grid-side converter is compared with the DC voltage reference value after passing through a low-pass filter to obtain a DC voltage difference;

[0148] The DC voltage difference is passed through a PI controller to obtain a power reference value;

[0149] Compare the grid connection point power with the power reference value after passing through a low-pass filter to obtain a power difference;

[0150] The power difference is passed through a PI controller to obtain an initial phase angle;

[0151] The initial phase angle is used to generate a second three-phase reference voltage via a reference wave generator;

[0152] The second three-phase reference voltage is passed through a PWM power drive module to obtain a PWM signal for controlling a grid-side converter in a grid-connected wind turbine system.

[0153] Furthermore, the calculation formula of the second three-phase reference voltage is as follows:

[0154]

[0155] In the above formula, u a_ref 、u b_ref 、u c_ref are the a, b, and c phase voltages of the second three-phase reference voltage, U m is the given voltage amplitude, f is the given frequency, t is the time, is the initial phase angle.

[0156] Example 3

[0157] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of a grid-connected wind turbine system control method in the above embodiment.

[0158] Example 4

[0159] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage device (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage device here can include both the built-in storage medium in the computer device and the extended storage medium supported by the computer device. The computer-readable storage device provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage device here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage device to implement the steps of a grid-connected wind turbine system control method in the above embodiment.

[0160] 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.

[0161] 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.

[0162] 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 including 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.

[0163] 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 in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0164] 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 control method for a grid-connected wind turbine system, characterized in that: The method comprises: Collect the frequency change and power of the grid connection point in the grid-connected wind turbine system; Generate a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the grid-connected point frequency variation; A PWM signal for controlling a grid-side converter in a grid-connected wind turbine system is generated based on the grid-connected point power.

2. The method according to claim 1, characterized in that The method of generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the grid-connected point frequency variation comprises: Generate a speed reference value based on the frequency change of the grid connection point; A PWM signal for controlling a machine-side converter in a grid-connected wind turbine system is generated based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value.

3. The method according to claim 2, characterized in that The calculation formula of the speed reference value is as follows: oh ref =2π(50±△f) In the above formula, ω ref is the speed reference value, △f is the frequency change of the grid connection point.

4. The method according to claim 2, characterized in that The method for generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value comprises: The electromagnetic torque of the permanent magnet synchronous generator is compared with the electromagnetic torque reference value of the permanent magnet synchronous generator and then integrated to obtain the rotation speed of the permanent magnet synchronous generator; The rotation speed of the permanent magnet synchronous generator is compared with a rotation speed reference value and then passed through a PI controller to obtain a q-axis current component; The d-axis current component and the q-axis current component are transformed by inverse Park to obtain a three-phase current reference value; The three-phase current sampling value is compared with the three-phase current reference value to obtain a first three-phase reference voltage through a differential controller; The first three-phase reference voltage is obtained through a PWM power drive module to obtain a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system; The coordinate angle required for the Park inverse transformation is the rotor angular displacement of the permanent magnet synchronous generator, and the d-axis current component is equal to 0.

5. The method according to claim 4, characterized in that The calculation formula of the electromagnetic torque reference value of the permanent magnet synchronous generator is as follows: In the above formula, T m_ref is the electromagnetic torque reference value of the permanent magnet synchronous generator, J is the moment of inertia, ω is the speed of the wind turbine mechanical shaft system, t is the time, T e is the electromagnetic torque of the permanent magnet synchronous generator.

6. The method according to claim 4, characterized in that The calculation formula of the first three-phase reference voltage is as follows: In the above formula, u abc_ref is the first three-phase reference voltage, L m is the equivalent inductance at the fan outlet, △i abc is the difference between the three-phase current reference value and the three-phase current sampling value, △t is the control period, i abc_ref is the three-phase current reference value, i abc is the three-phase current sampling value, and t is the time.

7. The method according to claim 1, characterized in that The method of generating a PWM signal for controlling a grid-side converter in a grid-connected wind turbine system based on the grid-connected point power comprises: The DC voltage of the grid-side converter is compared with the DC voltage reference value after passing through a low-pass filter to obtain a DC voltage difference; The DC voltage difference is passed through a PI controller to obtain a power reference value; Compare the grid connection point power with the power reference value after passing through a low-pass filter to obtain a power difference; The power difference is passed through a PI controller to obtain an initial phase angle; The initial phase angle is used to generate a second three-phase reference voltage via a reference wave generator; The second three-phase reference voltage is passed through a PWM power drive module to obtain a PWM signal for controlling a grid-side converter in a grid-connected wind turbine system.

8. The method according to claim 7, characterized in that The calculation formula of the second three-phase reference voltage is as follows: In the above formula, u a_ref 、u b_ref 、u c_ref are the a, b, and c phase voltages of the second three-phase reference voltage, U m is the given voltage amplitude, f is the given frequency, t is the time, is the initial phase angle.

9. A grid-connected wind turbine system control device, characterized in that: The device comprises: The acquisition module is used to collect the frequency change and power of the grid connection point in the grid-connected wind turbine system; A machine-side converter control module, used for generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the frequency variation of the grid-connected point; The grid-side converter control module is used to generate a PWM signal for controlling the grid-side converter in the grid-connected wind turbine system based on the grid-connected point power.

10. The device according to claim 9, characterized in that The machine-side converter control module is specifically used for: Generate a speed reference value based on the frequency change of the grid connection point; A PWM signal for controlling a machine-side converter in a grid-connected wind turbine system is generated based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value.

11. The device according to claim 10, characterized in that The calculation formula of the speed reference value is as follows: oh ref =2π(50±△f) In the above formula, ω ref is the speed reference value, △f is the frequency change of the grid connection point.

12. The device according to claim 10, characterized in that The method for generating a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system based on the electromagnetic torque and rotor angular displacement of the permanent magnet synchronous generator and the speed reference value comprises: The electromagnetic torque of the permanent magnet synchronous generator is compared with the electromagnetic torque reference value of the permanent magnet synchronous generator and then integrated to obtain the rotation speed of the permanent magnet synchronous generator; The rotation speed of the permanent magnet synchronous generator is compared with a rotation speed reference value and then passed through a PI controller to obtain a q-axis current component; The d-axis current component and the q-axis current component are transformed by inverse Park to obtain a three-phase current reference value; The three-phase current sampling value is compared with the three-phase current reference value to obtain a first three-phase reference voltage through a differential controller; The first three-phase reference voltage is obtained through a PWM power drive module to obtain a PWM signal for controlling a machine-side converter in a grid-connected wind turbine system; The coordinate angle required for the Park inverse transformation is the rotor angular displacement of the permanent magnet synchronous generator, and the d-axis current component is equal to 0.

13. The device according to claim 12, characterized in that The calculation formula of the electromagnetic torque reference value of the permanent magnet synchronous generator is as follows: In the above formula, T m_ref is the electromagnetic torque reference value of the permanent magnet synchronous generator, J is the moment of inertia, ω is the speed of the wind turbine mechanical shaft system, t is the time, T e is the electromagnetic torque of the permanent magnet synchronous generator.

14. The device according to claim 12, characterized in that The calculation formula of the first three-phase reference voltage is as follows: In the above formula, u abc_ref is the first three-phase reference voltage, L m is the equivalent inductance at the fan outlet, △i abc is the difference between the three-phase current reference value and the three-phase current sampling value, △t is the control period, i abc_ref is the three-phase current reference value, i abc is the three-phase current sampling value, and t is the time.

15. The device according to claim 9, characterized in that The grid-side converter control module is specifically used for: The DC voltage of the grid-side converter is compared with the DC voltage reference value after passing through a low-pass filter to obtain a DC voltage difference; The DC voltage difference is passed through a PI controller to obtain a power reference value; Compare the grid connection point power with the power reference value after passing through a low-pass filter to obtain a power difference; The power difference is passed through a PI controller to obtain an initial phase angle; The initial phase angle is used to generate a second three-phase reference voltage via a reference wave generator; The second three-phase reference voltage is passed through a PWM power drive module to obtain a PWM signal for controlling a grid-side converter in a grid-connected wind turbine system.

16. The device according to claim 15, characterized in that The calculation formula of the second three-phase reference voltage is as follows: In the above formula, u a_ref 、u b_ref 、u c_ref are the a, b, and c phase voltages of the second three-phase reference voltage, U m is the given voltage amplitude, f is the given frequency, t is the time, is the initial phase angle.

17. A computer device, characterized in that: include: one or more processors; The processor is configured to execute one or more programs; When the one or more programs are executed by the one or more processors, the grid-connected wind turbine system control method according to any one of claims 1 to 8 is implemented.

18. A computer readable storage device, characterized in that: A computer program is stored thereon, and when the computer program is executed, the control method for the grid-connected wind turbine system according to any one of claims 1 to 8 is implemented.

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