Method and device for controlling low-frequency oscillation of doubly-fed wind power grid-connected system, storage medium and electronic device

Abstract

The invention discloses a doubly-fed wind power grid-connected system low-frequency oscillation control method and device, a storage medium and an electronic device, and the method comprises the steps: calculating a reactive power given value of additional damping control based on an angular velocity difference and an additional damping controller transfer function under the condition that the doubly-fed wind power grid-connected system generates low-frequency oscillation, wherein the reactive power given value is used for providing additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency; superposing the reactive power given value to an existing reactive power reference value to obtain a target reactive power reference value; and inputting the target reactive power reference value and the actual reactive power value into a proportional-integral controller of the doubly-fed wind power grid-connected system to obtain a current control instruction output by the proportional-integral controller, and adjusting the low-frequency oscillation frequency according to the current control instruction. By adopting the technical scheme, the technical problem that the suppression effect on the low-frequency oscillation of the doubly-fed wind power grid-connected system is relatively poor is solved.

Description

Technical Field

[0001] The present application relates to the field of controlling low-frequency oscillations of a doubly-fed wind power grid-connected system, and specifically, to a method and device for controlling low-frequency oscillations of a doubly-fed wind power grid-connected system, a storage medium, and an electronic device. Background Art

[0002] As the installed capacity of wind power grid-connected continues to grow, the impact of the doubly-fed wind power grid-connected system on the power grid is gradually deepening. Due to the lack of reliable inertial response of the doubly-fed wind power grid-connected system converter and the complex interaction between the doubly-fed wind turbine and the synchronous generator, the system's anti-disturbance ability is reduced, causing complex low-frequency oscillations, thereby restricting the wind power absorption capacity. Low-frequency oscillation refers to the oscillation phenomenon with a frequency between 0.1Hz and 2.5Hz in the power system, which is usually caused by the interaction between the control mechanism in the system and the dynamic characteristics of the power grid, especially in the high-penetration wind power grid-connected system. This oscillation may cause unstable system operation, reduce the transmission capacity of the power system, and even cause more serious faults. Therefore, it is particularly important to study the low-frequency oscillation problem of the doubly-fed wind power grid-connected system under external disturbances.

[0003] When designing a plan to improve the dynamic and stable operating characteristics of a power grid that includes a doubly-fed wind power grid-connected system, the design and implementation are mainly considered from two perspectives: the power grid and the wind power system itself.

[0004] From the perspective of grid operation, due to the different electrical characteristics of the grid to which the wind power system is connected, the influence of the wind power system on the dynamic stability of the grid is also different, which may improve or worsen the oscillation characteristics of each oscillation mode of the original system. The doubly-fed wind power grid-connected system has flexible and controllable characteristics. By reasonably adding control links, the dynamic stability of the power system containing doubly-fed wind power grid-connected can be improved. In this regard, low-frequency oscillations can be suppressed by introducing a power system stabilizer to provide additional damping; in addition, a static synchronous compensator can be installed and adjusted with the active power on the transmission line as the input signal, thereby effectively suppressing the low-frequency oscillation of the doubly-fed wind power grid-connected system and enhancing the wind power system's absorption capacity. However, the power electronic converter has a low damping characteristic, and after the doubly-fed wind power generation equipment is connected to the grid, it is easy to cause the system to oscillate and become unstable due to insufficient damping.

[0005] Studying the low-frequency oscillation suppression control method from the perspective of the operation of the wind power system itself can serve as the key to the continuous grid-connected operation of the system, and can reduce the low-frequency oscillation of the power grid caused by the weak dynamic stability of the doubly-fed wind power grid-connected system from the root. Among them, the control system parameter optimization method refers to adjusting the control parameters offline or online according to the influence of the control parameters on the dynamic characteristics of the system, or using intelligent algorithms to increase the damping level of the system under the dominant oscillation mode, thereby improving the small signal stability of the new energy grid-connected system. The additional damping controller generates an additional control signal with adjustable phase and size through the compensation link by feeding back the oscillation signal, thereby suppressing the system oscillation.

[0006] In summary, it can be seen that there are some effective control strategies for suppressing low-frequency oscillations in grid-connected doubly-fed wind power grid-connected systems, including additional static synchronous compensators and other flexible control devices for power systems and adjusting the controllable parameters of the wind turbines themselves. However, the current control method strategy is not perfect enough. Although the control of additional equipment can suppress the low-frequency oscillations of the system to a certain extent, the inherent limitations of the equipment itself, such as cost, capacity, and response speed, limit the engineering practicality of this control strategy. In addition, there is a lack of in-depth research on the control mechanism of the wind power system itself, and the introduction of a single low-frequency oscillation suppression control link has limited effect on improving the low-frequency oscillation damping of the grid-connected doubly-fed wind power grid-connected system under full operating conditions. It can be seen that in the related technology, there is a technical problem of poor suppression effect on the low-frequency oscillation of the doubly-fed wind power grid-connected system.

[0007] With regard to the technical problem in the related technologies that the suppression effect of low-frequency oscillation of the doubly-fed wind power grid-connected system is poor, no effective solution has been proposed so far.

[0008] Therefore, it is necessary to improve the related technology to overcome the above-mentioned defects in the related technology. Summary of the invention

[0009] The embodiments of the present application provide a control method and device for low-frequency oscillation of a doubly-fed wind power grid-connected system, a storage medium and an electronic device, so as to at least solve the technical problem of poor suppression effect on low-frequency oscillation of a doubly-fed wind power grid-connected system.

[0010] According to one aspect of an embodiment of the present application, a method for controlling low-frequency oscillation of a doubly-fed wind power grid-connected system is provided, comprising: when low-frequency oscillation is detected in the doubly-fed wind power grid-connected system, calculating a reactive power set value of an additional damping control based on an angular velocity difference and a transfer function of an additional damping controller, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency; superimposing the reactive power set value on an existing reactive power reference value to obtain a target reactive power reference value; inputting the target reactive power reference value and an actual reactive power value into a proportional-integral controller of the doubly-fed wind power grid-connected system to obtain a current control instruction output by the proportional-integral controller, and adjusting the output current of the doubly-fed wind power grid-connected system according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system.

[0011] In an exemplary embodiment, the reactive power reference value of the additional damping control is calculated based on the angular velocity difference and the transfer function of the additional damping controller, including: calculating the reactive power reference value using the following formula: Q s_ref =K Q (s)·Δω Δ ; Among them, Q s_ref is the reactive power reference value, K Q (s) is the transfer function of the additional damping controller, Δω Δ is the angular velocity difference; determining the reactive power given value Q according to the reactive power reference value s ' _ref .

[0012] In an exemplary embodiment, before calculating the reactive power set value of the additional damping control based on the angular velocity difference and the additional damping controller transfer function, the method further includes: respectively acquiring the wind turbine speed of the doubly-fed wind power grid-connected system and the rotor speed of the doubly-fed wind power grid-connected system, and determining the angular velocity difference between the wind turbine speed and the rotor speed.

[0013] In an exemplary embodiment, before calculating the reactive power set value of the additional damping control based on the angular velocity difference and the additional damping controller transfer function, the method further includes: determining controller parameters of the additional damping controller, and determining the additional damping controller transfer function configured based on the controller parameters; wherein the additional damping controller transfer function is expressed as:

[0014]

[0015] Among them, K Q (s) represents the transfer function of the additional damping controller, s represents the function independent variable of the transfer function of the additional damping controller, KQc (s) represents the phase compensation gain parameter of the additional damping controller, K Qi (s) represents the DC isolation gain parameter of the additional damping controller, K Qd represents the damping controller gain parameter of the additional damping controller, T Qw is the time constant of the DC isolation link, T Q1 is the lead correction time constant, T Q2 is the hysteresis correction time constant.

[0016] In an exemplary embodiment, determining controller parameters of the additional damping controller includes: establishing a transfer function between an electromagnetic torque increment and a reactive power increment, and calculating a plurality of function values ​​of the transfer function at different oscillation frequencies; determining a target oscillation frequency from the plurality of function values, wherein a damping ratio corresponding to the target oscillation frequency is higher than a damping ratio of other oscillation frequencies, and a phase lag of the target oscillation frequency is greater than a phase lag of other oscillation frequencies; and configuring controller parameters required for the additional damping controller according to the damping ratio of the target oscillation frequency and the phase lag of the target oscillation frequency.

[0017] In an exemplary embodiment, controller parameters required for an additional damping controller are configured according to the damping ratio of the target oscillation frequency and the phase lag of the target oscillation frequency, including: determining a phase compensation gain parameter, a DC isolation gain parameter and a damping controller gain parameter based on the damping ratio of the target oscillation frequency; determining a DC isolation link time constant, an advance correction time constant and a lag correction time constant according to the phase lag of the target oscillation frequency, wherein the advance correction time constant and the lag correction time constant are used to compensate for the phase of the target oscillation frequency so that the compensated phase meets a preset value.

[0018] According to another aspect of an embodiment of the present application, a control device for low-frequency oscillation of a doubly-fed wind power grid-connected system is also provided, comprising: a calculation module, for calculating a reactive power set value of an additional damping control based on an angular velocity difference and a transfer function of an additional damping controller when low-frequency oscillation is detected in the doubly-fed wind power grid-connected system, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency; an obtaining module, for superimposing the reactive power set value on an existing reactive power reference value to obtain a target reactive power reference value; an adjustment module, for inputting the target reactive power reference value and an actual reactive power value into a proportional-integral controller of the doubly-fed wind power grid-connected system to obtain a current control instruction output by the proportional-integral controller, and adjusting the output current of the doubly-fed wind power grid-connected system according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system.

[0019] According to another aspect of the embodiments of the present application, a computer-readable storage medium is provided, in which a computer program is stored, wherein the computer program is configured to execute the above-mentioned method for controlling low-frequency oscillation of the doubly-fed wind power grid-connected system when running.

[0020] According to another aspect of the embodiments of the present application, an electronic device is also provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the control method for low-frequency oscillation of the doubly-fed wind power grid-connected system through the computer program.

[0021] According to another aspect of the present application, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the steps in any one of the above method embodiments are implemented.

[0022] Through the present application, when it is monitored that the doubly-fed wind power grid-connected system generates low-frequency oscillations, a reactive power set value of the additional damping control is calculated based on the angular velocity difference and the transfer function of the additional damping controller, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency; the reactive power set value is superimposed on the existing reactive power reference value to obtain a target reactive power reference value; the target reactive power reference value and the actual reactive power value are input into the proportional-integral controller of the doubly-fed wind power grid-connected system to obtain a current control instruction output by the proportional-integral controller, and the output current of the doubly-fed wind power grid-connected system is adjusted according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system. This application can effectively suppress low-frequency oscillations in the doubly-fed wind power grid-connected system by introducing an additional damping controller, thereby improving the stability and reliability of the system, exploring the coupling relationship between the electromagnetic, mechanical and control subsystems of the doubly-fed wind power grid-connected system, and using the transfer function of the additional damping controller to design a reasonable low-frequency oscillation suppression control strategy, so as to more effectively improve the anti-interference stability of the grid-connected doubly-fed wind power grid-connected system under the operating conditions of the whole system, thereby solving the technical problem of poor suppression effect on low-frequency oscillations of the doubly-fed wind power grid-connected system, and improving the suppression effect and control efficiency of low-frequency oscillations of the doubly-fed wind power grid-connected system. In practical applications, this application can significantly improve the power quality of the wind power grid-connected system, reduce the negative impact on the power grid, and play an important role in promoting the stable operation of large-scale wind power grid-connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0024] In order to more clearly illustrate the embodiments of the present application 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, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0025] Figure 1 It is a hardware structure block diagram of a mobile terminal of a method for controlling low-frequency oscillation of a double-fed wind power grid-connected system according to an embodiment of the present application;

[0026] Figure 2 is a flow chart of a method for controlling low-frequency oscillation of a doubly-fed wind power grid-connected system according to an embodiment of the present application;

[0027] Figure 3 It is a schematic diagram of RSC reactive-current loop control including a low-frequency oscillation suppression control link according to an embodiment of the present application;

[0028] Figure 4 is a schematic diagram of a simulated waveform of a rotor speed of a doubly-fed wind power grid-connected system according to an embodiment of the present application;

[0029] Figure 5 is a schematic diagram of a simulation waveform of active power of a double-fed wind power grid-connected system according to an embodiment of the present application;

[0030] Figure 6 A schematic diagram of a simulation waveform of a torsion angle between a wind turbine speed and a rotor speed in a doubly-fed wind power grid-connected system according to an embodiment of the present application;

[0031] Figure 7 It is a structural block diagram of a control device for low-frequency oscillation of a doubly-fed wind power grid-connected system according to an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0033] 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 data used in this way can be interchangeable 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. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0034] The method embodiments provided in the embodiments of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. Taking running on a mobile terminal as an example, Figure 1 1 is a hardware structure block diagram of a mobile terminal for a method for controlling low-frequency oscillation of a double-fed wind power grid-connected system according to an embodiment of the present application. Figure 1 As shown, the mobile terminal may include one or more ( Figure 1 Only one is shown in the figure) a processor 102 (the processor 102 may include but is not limited to a microprocessor or a processing device such as a programmable logic device (Field Programmable Gate Array, FPGA)) and a memory 104 for storing data, wherein the mobile terminal may also include a transmission device 106 and an input / output device 108 for communication functions. It can be understood by those skilled in the art that Figure 1 The structure shown is for illustration only and does not limit the structure of the mobile terminal. Figure 1 More or fewer components as shown, or with Figure 1 Different configurations shown.

[0035] The memory 104 can be used to store computer programs, for example, software programs and modules of application software, such as the computer program corresponding to the control method of low-frequency oscillation of the double-fed wind power grid-connected system in the embodiment of the present application. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, to implement the above method. The memory 104 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include a memory remotely arranged relative to the processor 102, and these remote memories may be connected to the mobile terminal via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0036] The transmission device 106 is used to receive or send data via a network. The specific example of the above network may include a wireless network provided by a communication provider of the mobile terminal. In one example, the transmission device 106 includes a network adapter (Network Interface Controller, referred to as NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission device 106 can be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0037] In this embodiment, a method for controlling low-frequency oscillation of a doubly-fed wind power grid-connected system is provided. Figure 2 is a flow chart of a method for controlling low-frequency oscillation of a doubly-fed wind power grid-connected system according to an embodiment of the present application. Figure 2 As shown, the process includes the following steps:

[0038] Step S202: when low-frequency oscillation is detected in the doubly-fed wind power grid-connected system, a reactive power set value of the additional damping control is calculated based on the angular velocity difference and the transfer function of the additional damping controller, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency;

[0039] Among them, the doubly fed wind power grid-connected system is equipped with a doubly fed induction generator (DFIG, Doubly Fed Induction Generator).

[0040] It should be noted that the RSC (Rotor Side Converter) control of DFIG includes active power control and reactive power control, in which the reactive power control loop is responsible for regulating the reactive power exchange between DFIG and the power grid to meet the needs of the power grid and maintain the operation stability of DFIG itself. One of the main goals of reactive power control is to ensure that DFIG can provide stable voltage support under various operating conditions, especially under disturbances such as power grid failure or wind speed changes. Rapid regulation of reactive power is crucial to maintaining system stability.

[0041] The low-frequency oscillation suppression control link introduced in this application means that a control strategy specifically for low-frequency oscillation is added to the conventional reactive power control logic. This link usually includes the detection, analysis and implementation of suppression measures of oscillation signals. Among them, oscillation signal detection refers to identifying the characteristic signal and frequency of low-frequency oscillation by monitoring system status, such as wind wheel speed, generator speed, output power, etc. Control parameter design refers to designing control parameters according to oscillation frequency and system characteristics, such as the proportional and integral gain of the PI controller, and the parameters of the damping controller such as damping gain, DC isolation link and phase compensation parameters. The process of implementing the suppression measures includes taking the detected oscillation signal as input, the designed control parameters as a guide, and generating an additional control signal, usually by adjusting the reactive power reference value to change the reactive output of the DFIG, so as to increase the system damping and suppress oscillation. This process is usually implemented in closed-loop control, that is, after the additional control signal is superimposed on the conventional control signal, it is further transmitted to the PI controller through the reactive power control loop of the RSC, and finally the output current of the RSC is adjusted to achieve the purpose of suppressing low-frequency oscillation and improving system stability.

[0042] Step S204: superimposing the reactive power set value onto the existing reactive power reference value to obtain a target reactive power reference value;

[0043] Step S206: Input the target reactive power reference value and the actual reactive power value into the proportional-integral controller of the doubly-fed wind power grid-connected system, obtain the current control instruction output by the proportional-integral controller, and adjust the output current of the doubly-fed wind power grid-connected system according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system.

[0044] Through the above steps, when it is monitored that the doubly-fed wind power grid-connected system generates low-frequency oscillation, the reactive power set value of the additional damping control is calculated based on the angular velocity difference and the transfer function of the additional damping controller, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency; the reactive power set value is superimposed on the existing reactive power reference value to obtain a target reactive power reference value; the target reactive power reference value and the actual reactive power value are input into the proportional-integral controller of the doubly-fed wind power grid-connected system to obtain a current control instruction output by the proportional-integral controller, and the output current of the doubly-fed wind power grid-connected system is adjusted according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system. This application can effectively suppress low-frequency oscillations in the doubly-fed wind power grid-connected system by introducing an additional damping controller, thereby improving the stability and reliability of the system, exploring the coupling relationship between the electromagnetic, mechanical and control subsystems of the doubly-fed wind power grid-connected system, and using the transfer function of the additional damping controller to design a reasonable low-frequency oscillation suppression control strategy, so as to more effectively improve the anti-interference stability of the grid-connected doubly-fed wind power grid-connected system under the operating conditions of the whole system, thereby solving the technical problem of poor suppression effect on low-frequency oscillations of the doubly-fed wind power grid-connected system, and improving the suppression effect and control efficiency of low-frequency oscillations of the doubly-fed wind power grid-connected system. In practical applications, this application can significantly improve the power quality of the wind power grid-connected system, reduce the negative impact on the power grid, and play an important role in promoting the stable operation of large-scale wind power grid-connected.

[0045] In an exemplary embodiment, for the implementation process of calculating the reactive power reference value of the additional damping control based on the angular velocity difference and the transfer function of the additional damping controller, the reactive power reference value can be calculated using the following formula: Q s_ref =K Q (s)·Δω Δ ; Among them, Q s_ref is the reactive power reference value, K Q (s) is the transfer function of the additional damping controller, Δω Δ is the angular velocity difference; determining the reactive power given value Q according to the reactive power reference value s ' _ref In this embodiment, the reactive power reference value calculated by the additional damping controller based on the angular velocity difference and the transfer function is adjusted to adjust the reactive power set value, thereby further optimizing the system's suppression effect on low-frequency oscillation.

[0046] In an exemplary embodiment, before calculating the reactive power set value of the additional damping control based on the angular velocity difference and the transfer function of the additional damping controller, further, the wind turbine speed of the doubly-fed wind power grid-connected system and the rotor speed of the doubly-fed wind power grid-connected system are respectively obtained, and the angular velocity difference between the wind turbine speed and the rotor speed is determined.

[0047] It should be noted that the above rotor speed represents the rotor speed of the rotor-side converter. The rotor speed reflects the mechanical state of the DFIG and is an important basis for achieving precise control and optimizing system performance. For example, the rotor speed is an input signal in the RSC control strategy, which is used to adjust the active and reactive power output of the DFIG. In the vector control of the DFIG, the rotor speed is used to calculate the dq axis components of the rotor current, which directly affect the electromagnetic torque and reactive power of the DFIG.

[0048] In wind power generation, DFIG needs to be able to adjust its operating state as wind speed changes to achieve maximum power point tracking. Real-time monitoring and control of the rotor speed can ensure that the DFIG maintains the best power generation efficiency and power output by adjusting the rotor current under changing wind speeds. DFIG can achieve variable speed constant frequency operation, that is, it can keep the output frequency constant when the rotor speed changes. This relies on the precise measurement and control of the rotor speed, adjusting the rotor current through RSC, and then controlling the output frequency of the generator to adapt to the frequency requirements of the power grid.

[0049] In this application, the angular velocity difference of the rotor speed (i.e., the difference between the generator speed and the synchronous speed) is used as the input of the additional damping controller, and the reactive power output of the generator is adjusted by controlling the reactive power reference value, thereby enhancing the damping of the system and suppressing low-frequency oscillations. Changes in the rotor speed can reflect the operating status of the generator, including load conditions, mechanical failures, etc. By continuously monitoring the rotor speed, potential operating anomalies can be discovered and handled in a timely manner, thereby improving the reliability and life of the DFIG. In the event of a system failure, such as a grid voltage drop or a sudden increase in wind speed, excessive rotor speed may damage the generator or converter. The control logic of the RSC can take protective measures based on the measurement of the rotor speed, such as reducing the rotor current, to prevent overspeed and overvoltage and protect the system safety.

[0050] In summary, in the control logic of RSC, by real-time monitoring and controlling the rotor speed, precise adjustment of the generator power output can be achieved, ensuring that the DFIG can operate efficiently and stably under various operating conditions, while effectively responding to grid disturbances, suppressing low-frequency oscillations, and improving the overall dynamic stability of the wind power system.

[0051] In an exemplary embodiment, before calculating the reactive power set value of the additional damping control based on the angular velocity difference and the additional damping controller transfer function, further, the controller parameters of the additional damping controller can be determined, and the additional damping controller transfer function configured based on the controller parameters can be determined; wherein the additional damping controller transfer function is expressed as:

[0052]

[0053] Among them, K Q (s) represents the transfer function of the additional damping controller, s represents the function independent variable of the transfer function of the additional damping controller, K Qc (s) represents the phase compensation gain parameter of the additional damping controller, K Qi (s) represents the DC isolation gain parameter of the additional damping controller, K Qd represents the damping controller gain parameter of the additional damping controller, T Qw is the time constant of the DC isolation link, T Q1 is the lead correction time constant, T Q2 is the hysteresis correction time constant.

[0054] For example, Figure 3 As shown, the dashed box is the additional low-frequency oscillation suppression control link in the present application, which means that an oscillation suppression control link with an angular velocity difference ΔωΔ as an input variable is added to the reactive power input port, and PI (Proportional Integral Controller) represents the reactive power loop PI controller and the RSC current inner loop PI controller respectively; Q s and Q s_ref Respectively represent the actual value and reference value of reactive power; Q s ' _ref Indicates the reactive power given value output by the additional damping controller; i rd and i rd_ref They represent the actual value and reference value of the d-axis component of the rotor current respectively; u rd and Δu rd They represent the d-axis component of the rotor voltage and its feedforward compensation term respectively; K Q (s) represents the transfer function of the additional damping controller; ω r ,ω t Represent the rotor angular velocity and mechanical angular velocity respectively. The corresponding working principle is: according to the low-frequency oscillation frequency (such as ω osc) near the amplitude and phase characteristics to design the parameters of the additional damping control link, thereby increasing the low-frequency oscillation damping of the doubly-fed wind power grid-connected system, thereby improving the dynamic stability of the system. By adding a damping control link to the RSC reactive-current control loop of the doubly-fed wind power grid-connected system, the low-frequency oscillation of the doubly-fed wind power grid-connected system can be suppressed, the damping level of the doubly-fed wind power grid-connected system can be improved, and the safe and stable operation capability of the system can be improved.

[0055] Among them, the parameters of the designed additional damping control link are the above-mentioned controller parameters.

[0056] In an exemplary embodiment, the process of determining the controller parameters of the additional damping controller is further described, specifically including: establishing a transfer function between the electromagnetic torque increment and the reactive power increment, and calculating multiple function values ​​of the transfer function at different oscillation frequencies; determining a target oscillation frequency from the multiple function values, wherein the damping ratio corresponding to the target oscillation frequency is higher than the damping ratio of other oscillation frequencies, and the phase lag of the target oscillation frequency is greater than the phase lag of other oscillation frequencies; configuring the controller parameters required for the additional damping controller according to the damping ratio of the target oscillation frequency and the phase lag of the target oscillation frequency. Among them, the target oscillation frequency represents the frequency at which low-frequency oscillation is prone to occur. The present application configures the controller parameters required for the additional damping controller by the damping ratio of the target oscillation frequency and the phase lag of the target oscillation frequency, which can increase the phase lead near the target oscillation frequency to improve damping, and amplify or weaken the oscillation signal by gain adjustment.

[0057] In an exemplary embodiment, the scheme of configuring the controller parameters required for the additional damping controller according to the damping ratio of the target oscillation frequency and the phase lag of the target oscillation frequency is implemented by the following process: determining the phase compensation gain parameter, the DC isolation gain parameter and the damping controller gain parameter based on the damping ratio of the target oscillation frequency; determining the DC isolation link time constant, the lead correction time constant and the lag correction time constant according to the phase lag of the target oscillation frequency, wherein the lead correction time constant and the lag correction time constant are used to compensate the phase of the target oscillation frequency so that the compensated phase meets the preset value. This embodiment can provide optimal damping for a specific oscillation frequency by accurately configuring the controller parameters, avoiding unnecessary energy consumption, and improving the economy and operation efficiency of the system. Among them, the preset value is, for example, 90°.

[0058] Optionally, in one embodiment, when the system detects low-frequency oscillation, the additional damping controller calculates an output signal (e.g., a reactive power set value) based on the input angular velocity difference signal ΔωΔ and the transfer function of the additional damping controller, and the output signal is used to provide additional damping near the oscillation frequency to suppress the oscillation. The reactive power set value is superimposed on the existing reactive power reference value in the RSC reactive power control link of the DFIG to form a new total reactive power reference value that includes the additional damping control effect. The total reactive power reference value is input into the PI controller, and the RSC reactive power is adjusted to the reference value using PI. PI outputs a set value i of the d-axis component of the RSC rotor current rd_ref , use i rd_ref The RSC is controlled to generate appropriate current, and then the reactive power output of the DFIG is adjusted, so as to effectively suppress the low-frequency oscillation of the entire wind power system. This embodiment adjusts the reactive power reference value through the monitored low-frequency oscillation signal, and then converts these adjustment values ​​into specific current control instructions through the PI controller, so as to effectively suppress the oscillation and improve the dynamic stability of the system.

[0059] Among them, PI can adjust the RSC rotor current d-axis component given value i by comparing the actual reactive power Qs with the total reactive power reference value, calculating the deviation between the two, and combining proportional and integral effects. rd_ref The proportional action responds quickly to deviations, while the integral action ensures that the deviations eventually approach zero, thus achieving steady-state control.

[0060] Based on the above embodiments, the present application proposes a method for suppressing low-frequency oscillation of a doubly-fed induction wind power system based on reactive power control under disturbance conditions such as sudden change in wind speed and short-circuit fault in the power grid. Specifically, from the perspective of active stabilization of the wind power system, without adding hardware equipment, the coupling relationship between the electromagnetic, mechanical and control subsystems of the doubly-fed wind power grid-connected system is utilized to suppress the low-frequency oscillation of the wind power system based on the angular velocity difference Δω. Δ As input variable, DFIG reactive power is added with given Q s_ref As the output variable, a low-frequency oscillation suppression control link is introduced into the RSC reactive power control loop. osc The amplitude and phase characteristics near the electromagnetic torque are used to design the parameters of the additional low-frequency oscillation suppression control link to increase the electromagnetic torque increment ΔT. e The angular velocity difference Δω Δ The projection in the negative direction increases the low-frequency oscillation damping of the doubly-fed wind power grid-connected system, thereby improving the dynamic stability of the system.

[0061] Obviously, the embodiments described above are only some embodiments of the present application, not all embodiments. In order to better understand the above method, the above process is described below in conjunction with the embodiments, but it is not intended to limit the technical solutions of the embodiments of the present application, specifically:

[0062] In an optional embodiment, the present application implements the suppression process of low-frequency oscillation of a doubly-fed induction wind power system based on reactive power control through the following steps. This suppression process can improve the dynamic stability of the doubly-fed wind power grid-connected system under disturbances such as sudden changes in wind speed and short-circuit faults in the power grid. The specific steps are as follows:

[0063] Step 1: When the double-fed wind power grid-connected system is disturbed by the external environment, the reactive power increment ΔQ of the double-fed wind turbine is s is the system input, with the electromagnetic torque increment ΔT e is the system output, and the electromagnetic torque increment ΔT is established according to the following formula: e and reactive power increment ΔQ s The transfer function G Q (s):

[0064] G Q (s) = ΔTe / ΔQs = C(sI-A)- 1 B.

[0065] in,

[0066] Among them, A, B, C are the coefficient matrices of the system state space model, Δx is the system state variable increment matrix, I represents the identity matrix, and s represents the independent variable of the transfer function. It can be understood that the Bode diagram in control theory can be used to analyze the transfer function G in the future. Q (s) frequency response. The Bode plot can show the frequency response of G Q (s) Gain (in dB) and phase (in degrees) at different frequencies. For example, the doubly-fed wind power grid-connected system has a gain of ω osc =0.5rad / s, it exhibits a lower damping ratio and a larger phase lag, and the system is prone to low-frequency oscillation at this frequency.

[0067] Step 2: According to the transfer function G in step 1 Q (s) Determine the low frequency oscillation frequency ω osc Nearby amplitude and phase characteristics (corresponding to the above damping ratio and phase lag);

[0068] Step 3: According to the low frequency oscillation frequency ω determined in step 2 osc The phase compensation gain parameter K of the additional damping controller is configured based on the amplitude and phase characteristics near Qc , DC blocking gain parameter K Qiand the damping controller gain parameter K Qd , calculate the additional damping controller transfer function K according to the following formula: Q (s):

[0069]

[0070] Among them, T Qw is the time constant of the DC isolation link, T Q1 and T Q2 are respectively the leading correction time constant and the lagging correction time constant, K Qd is the damping controller gain.

[0071] Among them, K Qd Used to adjust the system osc The controller output is adjusted based on the damping requirement at the frequency to ensure that the additional control signal can effectively suppress oscillations without causing the system to over-regulate. Qd =100 or an appropriate value, and then fine-tune through simulation and testing.

[0072] According to G Q (s) in ω osc The amplitude and phase characteristics near ω can be compensated by using an additional damping controller to increase the damping of the system and reduce the phase lag, thereby suppressing low-frequency oscillations. The choice of gain needs to consider the system at ω osc The damping requirements under the control and the stability requirements of the controller.

[0073] For example, in the DC isolation link, set the DC isolation link time constant T Qw and DC blocking gain parameter K Qi The DC isolation link is used to remove the DC component of the transfer function, prevent the controller from generating unnecessary offsets in steady state, and ensure that the controller only works on AC oscillation signals. The time constant of the DC isolation link can be selected as a multiple of the oscillation period to achieve a DC isolation link time constant that is much smaller than the oscillation period, for example, T Qw = 0.001s. This ensures that the low frequency oscillation signal can pass through while the DC component is suppressed.

[0074] In the phase compensation link, set the lead correction time constant T Q1 , hysteresis correction time constant T Q2 and phase compensation gain parameter K Qc The phase compensation link is used to osc Additional phase lead compensation is provided by adjusting T Q1 and T Q2 , can increase the damping of the system at a specific frequency. Q1 and T Q2 The choice ofosc The phase lag at t is determined to ensure that the compensated phase is close to 90°, which is a general principle in the design of phase advance controllers. For example, T Q1 = 0.05s and T Q2 =0.2s to provide a phase lead of about 30° around ωosc.

[0075] Step 4: The angular velocity difference Δω between the wind rotor (wind turbine speed) and the generator electrical angular velocity (rotor speed of the double-fed wind power grid-connected system) Δ Input into the additional damping controller, according to step 1 and step 2, the output reactive power reference value Q of the additional damping controller is determined according to the following formula: s ' _ref :

[0076] Q s ' _ref =K Q (s)·Δω Δ .

[0077] Step 5: Add the additional damping controller output Q in step 4 s ' _ref As the reactive power given value, it is superimposed on the RSC reactive power control link of the double-fed wind power grid-connected system, and finally outputted as the reference value of the RSC rotor current d-axis component by the controller (Proportional Integral Controller), and this reference value is set as the given value i rd_ref . Among them, PI is used to control the rotor current d-axis component of the rotor side converter (RSC) of the doubly fed induction generator (DFIG). In this way, by processing the input signal (such as i rd ) and the expected reference signal (e.g. rd_ref ) and generates control signals to adjust the system to achieve the desired steady-state and dynamic performance.

[0078] Furthermore, the simulation results based on the above method and the traditional control method under three-phase short circuit fault are compared. Figures 4 to 6 As shown in the figure, at t = 2s, a three-phase symmetrical short circuit fault occurs in the power grid, and at t = 2.2s, the short circuit fault is cleared. Figure 4 (a) and Figure 4 (b) and Figure 6 It can be seen that after the short circuit fault is cleared, the wind turbine speed ω t 、Rotor speed of doubly-fed wind power grid-connected systemω r And the torsion angle (i.e. angular velocity difference) θ between the two need to go through the corresponding oscillation process before reaching its steady-state value. Correspondingly, Figure 5 (a) and Figure 5(b) The system active output P g The time domain simulation waveform also shows a dynamic process from oscillation gradually decaying to reaching a steady state.

[0079] contrast Figures 4 to 6 It can be seen from the solid curve and the dotted curve in that the low-frequency oscillation suppression control method of the present application increases the speed ω of the wind turbine. t 、Rotor speed of doubly-fed wind power grid-connected systemω r The oscillation attenuation speed of the torsion angle θ between the two speeds up the system to enter a stable operating state after fault recovery, that is, it increases the low-frequency oscillation damping of the system. At the same time, it reduces the active power P of the grid-connected double-fed wind power grid-connected system. g The oscillation of the wind power system is reduced, which reduces the probability of low-frequency oscillation in the wind power grid, and effectively improves the dynamic and stable operation characteristics of the wind power system itself and the grid to which it is connected.

[0080] Through the above embodiments, the present application starts from the perspective of active stabilization of the wind power system, without adding hardware equipment, if the system is disturbed by sudden changes in wind speed and short-circuit faults in the power grid, the coupling relationship between the electromagnetic, mechanical and control subsystems of the double-fed wind power grid-connected system is utilized, and a low-frequency oscillation suppression control link is introduced into the RSC reactive power control loop, which can effectively increase the electromagnetic torque increment ΔT. e The angular velocity difference Δω Δ The projection in the negative direction increases the low-frequency oscillation damping of the doubly-fed wind power grid-connected system, thereby improving the dynamic stability of the system shaft system.

[0081] Through the description of the above implementation methods, those skilled in the art can clearly understand that the method according to the above embodiment can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods of each embodiment of the present application.

[0082] In this embodiment, a control device for low-frequency oscillation of a doubly-fed wind power grid-connected system is also provided, which is used to implement the above-mentioned embodiments and preferred implementation modes, and will not be repeated hereafter. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0083] Figure 7 : is a structural block diagram of a control device for low-frequency oscillation of a doubly-fed wind power grid-connected system according to an embodiment of the present application, the device comprising:

[0084] A calculation module 72 is used to calculate a reactive power set value of the additional damping control based on the angular velocity difference and the transfer function of the additional damping controller when low-frequency oscillation is detected in the double-fed wind power grid-connected system, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency;

[0085] An obtaining module 74 is used to superimpose the reactive power given value onto the existing reactive power reference value to obtain a target reactive power reference value;

[0086] The adjustment module 76 is used to input the target reactive power reference value and the actual reactive power value into the proportional-integral controller of the doubly-fed wind power grid-connected system, obtain the current control instruction output by the proportional-integral controller, and adjust the output current of the doubly-fed wind power grid-connected system according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system.

[0087] By means of the above-mentioned device, when it is monitored that the doubly-fed wind power grid-connected system generates low-frequency oscillation, a reactive power set value of the additional damping control is calculated based on the angular velocity difference and the transfer function of the additional damping controller, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency; the reactive power set value is superimposed on the existing reactive power reference value to obtain a target reactive power reference value; the target reactive power reference value and the actual reactive power value are input into the proportional-integral controller of the doubly-fed wind power grid-connected system to obtain a current control instruction output by the proportional-integral controller, and the output current of the doubly-fed wind power grid-connected system is adjusted according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system. This application can effectively suppress low-frequency oscillations in the doubly-fed wind power grid-connected system by introducing an additional damping controller, thereby improving the stability and reliability of the system, exploring the coupling relationship between the electromagnetic, mechanical and control subsystems of the doubly-fed wind power grid-connected system, and using the transfer function of the additional damping controller to design a reasonable low-frequency oscillation suppression control strategy, so as to more effectively improve the anti-interference stability of the grid-connected doubly-fed wind power grid-connected system under the operating conditions of the whole system, thereby solving the technical problem of poor suppression effect on low-frequency oscillations of the doubly-fed wind power grid-connected system, and improving the suppression effect and control efficiency of low-frequency oscillations of the doubly-fed wind power grid-connected system. In practical applications, this application can significantly improve the power quality of the wind power grid-connected system, reduce the negative impact on the power grid, and play an important role in promoting the stable operation of large-scale wind power grid-connected.

[0088] In an exemplary embodiment, the calculation module is further used to calculate the reactive power reference value using the following formula: Q s_ref =K Q (s)·Δω Δ ; Among them, Q s_ref is the reactive power reference value, K Q (s) is the transfer function of the additional damping controller, Δω Δ is the angular velocity difference; determining the reactive power given value Q according to the reactive power reference value s ' _ref .

[0089] In an exemplary embodiment, the calculation module is also used to: before calculating the reactive power set value of the additional damping control based on the angular velocity difference and the transfer function of the additional damping controller, respectively obtain the wind turbine speed of the doubly fed wind power grid-connected system and the rotor speed of the doubly fed wind power grid-connected system, and determine the angular velocity difference between the wind turbine speed and the rotor speed.

[0090] In an exemplary embodiment, the calculation module is further used to: determine the controller parameters of the additional damping controller before calculating the reactive power set value of the additional damping control based on the angular velocity difference and the additional damping controller transfer function, and determine the additional damping controller transfer function configured based on the controller parameters; wherein the additional damping controller transfer function is expressed as:

[0091]

[0092] Among them, K Q (s) represents the transfer function of the additional damping controller, s represents the function independent variable of the transfer function of the additional damping controller, K Qc (s) represents the phase compensation gain parameter of the additional damping controller, K Qi (s) represents the DC isolation gain parameter of the additional damping controller, K Qd represents the damping controller gain parameter of the additional damping controller, T Qw is the time constant of the DC isolation link, T Q1 is the lead correction time constant, T Q2 is the hysteresis correction time constant.

[0093] In an exemplary embodiment, the calculation module is also used to: establish a transfer function between the electromagnetic torque increment and the reactive power increment, and calculate multiple function values ​​of the transfer function at different oscillation frequencies; determine a target oscillation frequency from the multiple function values, wherein the damping ratio corresponding to the target oscillation frequency is higher than the damping ratios of other oscillation frequencies, and the phase lag of the target oscillation frequency is greater than the phase lag of other oscillation frequencies; and configure controller parameters required for the additional damping controller according to the damping ratio of the target oscillation frequency and the phase lag of the target oscillation frequency.

[0094] In an exemplary embodiment, the calculation module is also used to: determine the phase compensation gain parameter, the DC isolation gain parameter and the damping controller gain parameter based on the damping ratio of the target oscillation frequency; determine the DC isolation link time constant, the lead correction time constant and the lag correction time constant according to the phase lag of the target oscillation frequency, wherein the lead correction time constant and the lag correction time constant are used to compensate for the phase of the target oscillation frequency so that the compensated phase meets the preset value.

[0095] An embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored, wherein the computer program is configured to execute the steps of any of the above method embodiments when running.

[0096] Optionally, in this embodiment, the storage medium may be configured to store a computer program for performing the following steps:

[0097] S1, when monitoring that the doubly-fed wind power grid-connected system generates low-frequency oscillation, calculating a reactive power set value of an additional damping control based on an angular velocity difference and a transfer function of an additional damping controller, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency;

[0098] S2, superimposing the reactive power set value onto the existing reactive power reference value to obtain a target reactive power reference value;

[0099] S3, inputting the target reactive power reference value and the actual reactive power value into the proportional-integral controller of the doubly-fed wind power grid-connected system, obtaining the current control instruction output by the proportional-integral controller, and adjusting the output current of the doubly-fed wind power grid-connected system according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system.

[0100] In an exemplary embodiment, the computer-readable storage medium may include, but is not limited to, various media that can store computer programs, such as a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0101] For specific examples in this embodiment, reference may be made to the examples described in the above embodiments and exemplary implementation modes, and this embodiment will not be described in detail herein.

[0102] An embodiment of the present application further provides an electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to run the computer program to execute the steps in any one of the above method embodiments.

[0103] Optionally, in this embodiment, the processor may be configured to perform the following steps through a computer program:

[0104] S1, when monitoring that the doubly-fed wind power grid-connected system generates low-frequency oscillation, calculating a reactive power set value of an additional damping control based on an angular velocity difference and a transfer function of an additional damping controller, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency;

[0105] S2, superimposing the reactive power set value onto the existing reactive power reference value to obtain a target reactive power reference value;

[0106] S3, inputting the target reactive power reference value and the actual reactive power value into the proportional-integral controller of the doubly-fed wind power grid-connected system, obtaining the current control instruction output by the proportional-integral controller, and adjusting the output current of the doubly-fed wind power grid-connected system according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system.

[0107] In an exemplary embodiment, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor, and the input / output device is connected to the processor.

[0108] An embodiment of the present application further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the steps in any one of the above method embodiments are implemented.

[0109] An embodiment of the present application further provides another computer program product, including a non-volatile computer-readable storage medium, wherein the non-volatile computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps in any of the above method embodiments are implemented.

[0110] An embodiment of the present application also provides a computer program, which includes computer instructions, which are stored in a computer-readable storage medium; a processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the steps in any one of the above method embodiments.

[0111] For specific examples in this embodiment, reference may be made to the examples described in the above embodiments and exemplary implementation modes, and this embodiment will not be described in detail herein.

[0112] Obviously, those skilled in the art should understand that the above modules or steps of the present application can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order from that herein, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present application is not limited to any specific combination of hardware and software.

[0113] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for controlling low-frequency oscillation of a double-fed wind power grid-connected system, characterized in that: The additional damping controller applied to the double-fed wind power grid-connected system comprises: When low-frequency oscillation is detected in the doubly-fed wind power grid-connected system, a reactive power set value of the additional damping control is calculated based on the angular velocity difference and the transfer function of the additional damping controller, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency; The reactive power given value is superimposed on the existing reactive power reference value to obtain a target reactive power reference value; The target reactive power reference value and the actual reactive power value are input into the proportional-integral controller of the doubly-fed wind power grid-connected system to obtain a current control instruction output by the proportional-integral controller, and the output current of the doubly-fed wind power grid-connected system is adjusted according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system.

2. The method according to claim 1, characterized in that The reactive power reference value of the additional damping control is calculated based on the angular velocity difference and the transfer function of the additional damping controller, including: The reactive power reference value is calculated using the following formula: Q s_ref =K Q (s)·See Δ ; Among them, Q s_ref is the reactive power reference value, K Q (s) is the transfer function of the additional damping controller, Δω Δ is the angular velocity difference; Determine the reactive power set value Q according to the reactive power reference value s ' _ref .

3. The method according to claim 1, characterized in that Before calculating the reactive power set value of the additional damping control based on the angular velocity difference and the transfer function of the additional damping controller, the method further includes: The wind turbine rotation speed of the double-fed wind power grid-connected system and the rotor rotation speed of the double-fed wind power grid-connected system are respectively acquired, and the angular velocity difference between the wind turbine rotation speed and the rotor rotation speed is determined.

4. The method according to claim 1, characterized in that: Before calculating the reactive power set value of the additional damping control based on the angular velocity difference and the additional damping controller transfer function, the method further includes: Determining controller parameters of the additional damping controller, and determining a transfer function of the additional damping controller configured based on the controller parameters; Wherein, the transfer function of the additional damping controller is expressed as: Among them, K Q (s) represents the transfer function of the additional damping controller, s represents the function independent variable of the transfer function of the additional damping controller, K Qc (s) represents the phase compensation gain parameter of the additional damping controller, K Qi (s) represents the DC isolation gain parameter of the additional damping controller, K Qd represents the damping controller gain parameter of the additional damping controller, T Qw is the time constant of the DC isolation link, T Q1 is the lead correction time constant, T Q2 is the hysteresis correction time constant.

5. The method according to claim 4, characterized in that Determining controller parameters of the additional damping controller includes: Establishing a transfer function between an electromagnetic torque increment and a reactive power increment, and calculating a plurality of function values ​​of the transfer function at different oscillation frequencies; Determining a target oscillation frequency from the multiple function values, wherein a damping ratio corresponding to the target oscillation frequency is higher than damping ratios of other oscillation frequencies, and a phase lag of the target oscillation frequency is greater than phase lags of other oscillation frequencies; Controller parameters required by the additional damping controller are configured according to the damping ratio of the target oscillation frequency and the phase lag amount of the target oscillation frequency.

6. The method according to claim 5, characterized in that Configuring controller parameters required for the additional damping controller according to the damping ratio of the target oscillation frequency and the phase lag of the target oscillation frequency includes: Determining a phase compensation gain parameter, a DC isolation gain parameter, and a damping controller gain parameter based on the damping ratio of the target oscillation frequency; The DC isolation link time constant, the lead correction time constant and the lag correction time constant are determined according to the phase lag of the target oscillation frequency, wherein the lead correction time constant and the lag correction time constant are used to compensate the phase of the target oscillation frequency so that the compensated phase meets the preset value.

7. A control device for low frequency oscillation of a double-fed wind power grid-connected system, characterized in that: include: A calculation module, configured to calculate a reactive power set value of an additional damping control based on an angular velocity difference and a transfer function of an additional damping controller when low-frequency oscillation is detected in the double-fed wind power grid-connected system, wherein the reactive power set value is used to provide additional damping for the low-frequency oscillation frequency to suppress the low-frequency oscillation frequency; An obtaining module is used to superimpose the reactive power given value onto the existing reactive power reference value to obtain a target reactive power reference value; The adjustment module is used to input the target reactive power reference value and the actual reactive power value into the proportional-integral controller of the doubly-fed wind power grid-connected system, obtain the current control instruction output by the proportional-integral controller, and adjust the output current of the doubly-fed wind power grid-connected system according to the current control instruction to suppress the low-frequency oscillation frequency of the doubly-fed wind power grid-connected system.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein the program executes the method according to any one of claims 1 to 6 when executed.

9. An electronic device comprising a memory and a processor, characterized in that: A computer program is stored in the memory, and the processor is configured to execute the method according to any one of claims 1 to 6 through the computer program.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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