Parameter threshold cooperative power support method and system for grid-forming wind storage system

Abstract

The present application relates to the technical field of power system frequency control, and especially relates to a parameter threshold cooperative power support method and system of a grid-connected wind storage system, which comprises the following steps: when the system frequency deviation is less than the lower limit of the frequency threshold, determining that the disturbance is a small disturbance, and the energy storage module does not respond, and only the rotor maintains the stability of the direct current voltage; when the disturbance causes the frequency deviation of the wind storage system to be greater than the upper limit of the frequency threshold, determining that the disturbance is a large disturbance, and at this time, the rotor and the energy storage module jointly maintain the stability of the direct current voltage, and cooperative support on the direct current side is realized. The present application can reduce the charging and discharging times of the energy storage module on the basis of ensuring that the rotor speed does not fluctuate greatly, improve the service life of the energy storage module of the wind storage system, effectively maintain the stability of the power grid frequency, and ensure the economy of the grid-connected direct-drive wind storage system.

Description

Technical Field

[0001] This invention relates to the field of power system frequency control technology, and in particular to a parameter threshold coordinated power support method and system for a grid-type wind-storage system. Background Technology

[0002] With increasing environmental pollution and escalating energy shortages, wind power, as one of the most technologically mature new energy sources, is seeing its penetration rate in power systems continuously rise. Currently, most wind turbines employ grid-following control, relying on phase-locked loops (PLLs) to synchronize with the AC grid by following its frequency and phase. This approach struggles to operate stably under weak grid conditions and lacks grid support capabilities. Grid-based wind power systems, with their ability to autonomously construct their own frequency and phase, can achieve faster frequency response and have attracted widespread attention.

[0003] Grid-connected wind power systems require a corresponding frequency regulation cost to support grid frequency. Wind turbine rotors possess rotational kinetic energy, which can effectively support system frequency stability. However, utilizing rotor power for frequency regulation sacrifices the maximum power capacity of the wind power system, and the limited energy storage weakens the regulation effect to some extent. Energy storage systems offer advantages such as fast response speed and accurate tracking of active power commands. Through optimized control system design, rapid inertial response and continuous active power support can be achieved. Therefore, it is necessary to equip wind farms with a certain proportion of energy storage modules.

[0004] In summary, the collaborative control principle of a grid-connected direct-drive wind and energy storage system with a back-to-back converter as the grid interface should meet the following requirements: (1) When the system frequency deviation is less than the lower limit of the frequency threshold, the load disturbance is judged as a small disturbance, and the rotor provides all the supporting power; (2) When the system frequency deviation is greater than the upper limit of the frequency threshold, the load disturbance is judged as a large disturbance, the energy storage module operates, and together with the rotor, maintains the DC voltage stability and provides supporting power to the grid side; (3) On the basis of ensuring that the rotor speed does not fluctuate within a large range, the number of charging and discharging cycles of the energy storage module can be reduced, thereby improving the service life of the energy storage module in the grid-connected direct-drive wind and energy storage system. Summary of the Invention

[0005] In view of at least one of the above technical problems, the present invention provides a parameter threshold coordinated power support method and system for a grid-type wind-storage system to solve the problem that the typical control strategy of the existing direct-drive wind-storage system cannot coordinate the output of the wind turbine rotor and the energy storage module.

[0006] According to a first aspect of the present invention, a method for parameter threshold coordinated power support in a grid-type wind-storage system is provided, comprising:

[0007] Obtain the upper frequency threshold |Δf of the grid-type wind-storage systemth h |、Frequency lower limit threshold|Δf th l |and frequency deviation|Δf|;

[0008] Based on the upper frequency threshold |Δf th h The magnitude of the frequency deviation |Δf| determines whether the load disturbance is a large disturbance, and determines the S-state value of the hysteresis module;

[0009] Based on the lower frequency threshold |Δf th l The magnitude of the frequency deviation |Δf| is used to determine whether the load disturbance is a small disturbance and to determine the S-state value of the hysteresis module.

[0010] Obtain the S-state value of the hysteresis module, and the reference value U of the DC capacitor voltage of the energy storage converter voltage loop parameter. dcref and DC capacitor voltage U dc ;

[0011] The response strategy is determined based on the state value of the hysteresis module. During small disturbances, S=0, the outer voltage loop does not participate in control, and only the inner current loop controls the energy storage converter, generating the energy storage converter current reference value i. ESref ;

[0012] The response strategy is determined based on the state value of the hysteresis module. During large disturbances, S=1, the outer voltage loop participates in the control, and a reference value i for the energy storage converter current is generated. ESref ;

[0013] Obtain the current i of the energy storage converter ES ;

[0014] According to the current reference value i ESref and energy storage converter current i ES After differential operation, a PWM waveform is generated through a PI circuit to control the energy storage converter.

[0015] In some embodiments of the present invention, the criteria for determining the large disturbance are as follows:

[0016]

[0017] In some embodiments of the present invention, the criteria for determining the small perturbation are as follows:

[0018]

[0019] In some embodiments of the present invention, the judgment logic of the hysteresis module S is as follows:

[0020]

[0021] That is, under small disturbances, S=0, and the DC voltage is maintained by the direct-drive fan rotor alone; under large disturbances, S=1, and the DC voltage is maintained by the rotor and the energy storage module together, realizing coordinated support on the DC side.

[0022] In some embodiments of the present invention, the current reference value i Esref The acquisition process is as follows:

[0023] When S=0, the outer voltage loop does not participate in the control, and the current reference value i Esref =0;

[0024] When S=1, the outer voltage loop participates in the control, and a current reference value i is generated through the PI circuit. Esref .

[0025] In some embodiments of the present invention, the PWM signal generation process of the energy storage converter is as follows:

[0026] Current reference value i ESref and energy storage converter current i ES After differential operation, a PWM waveform is generated through a PI circuit to control the energy storage converter.

[0027] According to a second aspect of the present invention, a parameter threshold coordinated power support control system for a grid-type wind-storage system is also provided, comprising:

[0028] The data acquisition module is used to obtain the absolute value of the upper frequency threshold |Δf of the grid-type wind-storage system. th h |, Absolute value of the lower frequency threshold|Δf th l | Absolute value of frequency deviation |Δf| Reference value of DC capacitor voltage U dcref DC capacitor voltage U dc and energy storage converter current i ES ;

[0029] The judgment module is used to determine the magnitude of the absolute value of the frequency deviation, |Δf|, and to determine whether it is a large or small disturbance based on its magnitude.

[0030] The hysteresis module is used to control the activation of the outer voltage loop of the energy storage converter. When S is set to 0, the outer voltage loop of the energy storage module is not activated, and when S is set to 1, the outer voltage loop of the energy storage module is activated.

[0031] The current calculation module is used to calculate the current based on the DC capacitor voltage reference value U. dcref and DC capacitor voltage U dc The difference is used to obtain the reference value i of the energy storage converter current through the proportional-integral control module. Esref And the current loop generates the PWM control signal for the energy storage converter;

[0032] The control module is used to control the output power of the wind turbine based on the PWM control signal of the energy storage converter.

[0033] According to a third aspect of the present invention, a computer-readable storage medium is also provided, wherein a computer program is stored therein, and when executed by a processor, the computer program implements the method as described in any one of claims 1-6.

[0034] According to a fourth aspect of the present invention, an electronic device is also provided, comprising:

[0035] Memory, used to store computer programs;

[0036] A processor for executing the computer program to implement the method as described in any one of the first or second aspects.

[0037] According to a fifth aspect of the invention, a computer program product is also provided, comprising a computer program that, when executed by a processor, implements the method as described in any one of the first or second aspects.

[0038] The beneficial effects of this invention are as follows: This invention distinguishes between large and small disturbances using a frequency threshold and incorporates a hysteresis module into the collaborative criterion. During small disturbances, the direct-drive wind turbine rotor provides all the supporting power; during large disturbances, the energy storage module activates, working with the rotor to maintain DC voltage stability and providing supporting power for the DC capacitor. This achieves collaborative support between the rotor and the energy storage module for the DC side of the grid-type direct-drive wind-storage system. This invention can reduce the number of charge-discharge cycles of the energy storage module while ensuring that the rotor speed does not fluctuate within a large range, thus improving the service life of the energy storage module in the grid-type direct-drive wind-storage system and contributing to the long-term stable operation of the system. For power system frequency control, this invention can effectively maintain grid frequency stability, improve the economy of the grid-type direct-drive wind-storage system, and enhance the reliability and lifespan of the energy storage module under the premise of small fluctuations in the direct-drive wind turbine rotor speed. It has practical engineering application value and economic benefits. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the grid-connected interface of a direct-drive wind-storage system in an embodiment of the present invention;

[0041] Figure 2This is the machine-side converter control strategy in the embodiments of the present invention;

[0042] Figure 3 This is the grid-side converter control strategy in this embodiment of the invention;

[0043] Figure 4 This is the energy storage converter control strategy in the embodiments of the present invention;

[0044] Figure 5 This describes the collaborative mechanism in the embodiments of the present invention;

[0045] Figure 6 This is a specific collaborative control block diagram in an embodiment of the present invention;

[0046] Figure 7 This invention presents a comparison of system frequency waveforms under three scenarios: a parameter threshold coordinated power control strategy under random disturbances, no response from the energy storage module to frequency changes, and full response from the energy storage module.

[0047] Figure 8 This invention presents a comparison of grid-side output power waveforms under three scenarios: a parameter threshold coordinated power control strategy under random disturbances, no response from the energy storage module to frequency changes, and a complete response from the energy storage module.

[0048] Figure 9 This invention presents a comparison of the rotor speed waveforms of direct-drive wind turbines under three scenarios: a parameter threshold coordinated power control strategy under random disturbances, a scenario where the energy storage module does not respond to frequency changes, and a scenario where the energy storage module is the sole responder.

[0049] Figure 10 This invention presents a comparison of energy storage module power under three scenarios: a parameter threshold coordinated power control strategy under random disturbances, energy storage module not responding to frequency changes, and energy storage module responding entirely.

[0050] Figure 11 This invention presents a comparison of battery state-of-charge waveforms under three scenarios: a parameter threshold coordinated power control strategy under random disturbances, a scenario where the energy storage module does not respond to frequency changes, and a scenario where the energy storage module responds entirely.

[0051] Figure 12 This invention presents a comparison of the number of energy storage response times under three scenarios: a parameter threshold coordinated power control strategy under random disturbances, energy storage modules not responding to frequency changes, and energy storage modules responding entirely.

[0052] Figure 13 This invention presents statistics on the number of energy storage responses under three scenarios: a parameter threshold coordinated power control strategy under random disturbances, energy storage modules not responding to frequency changes, and energy storage modules responding entirely.

[0053] Figure 14This is a flowchart of the parameter threshold coordinated power support method for a grid-type wind-storage system in an embodiment of the present invention. Detailed Implementation

[0054] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0055] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] like Figure 14 The parameter threshold coordinated power support method for the grid-type wind-storage system shown includes the following steps:

[0058] Obtain the upper frequency threshold |Δf of the grid-type wind-storage system th h |、Frequency lower limit threshold|Δf th l |and frequency deviation|Δf|;

[0059] Based on the upper frequency threshold |Δf th h The magnitude of the frequency deviation |Δf| determines whether the load disturbance is a large disturbance, and determines the S-state value of the hysteresis module;

[0060] Based on the lower frequency threshold |Δf th l The magnitude of the frequency deviation |Δf| is used to determine whether the load disturbance is a small disturbance and to determine the S-state value of the hysteresis module.

[0061] Obtain the S-state value of the hysteresis module, and the reference value U of the DC capacitor voltage of the energy storage converter voltage loop parameter. dcref and DC capacitor voltage U dc ;

[0062] The response strategy is determined based on the state value of the hysteresis module. During small disturbances, S=0, the outer voltage loop does not participate in control, and only the inner current loop controls the energy storage converter, generating the energy storage converter current reference value i. ESref ;

[0063] The response strategy is determined based on the state value of the hysteresis module. During large disturbances, S=1, the outer voltage loop participates in the control, and a reference value i for the energy storage converter current is generated. ESref ;

[0064] Obtain the current i of the energy storage converter ES ;

[0065] According to the current reference value i ESref and energy storage converter current i ES After the difference is calculated, a PWM waveform is generated through a PI circuit to control the energy storage converter.

[0066] The parameter threshold coordinated power support method of the grid-type wind-storage system can coordinate the direct-drive wind turbine rotor and the energy storage module to jointly respond to system frequency changes. When the grid-type direct-drive wind-storage system encounters a disturbance, the rotor first provides frequency regulation support power to the DC capacitor. At the same time, its frequency deviation is measured. If the frequency deviation is less than the lower limit of the frequency threshold, the energy storage module is not activated, and only the direct-drive wind turbine rotor supports the disturbance power by sacrificing its speed. If the frequency deviation is greater than the upper limit of the frequency threshold, the energy storage module is activated, and the direct-drive wind turbine rotor and the energy storage module jointly maintain the DC voltage stability, thereby achieving coordinated support for the DC capacitor.

[0067] The control method proposed in this invention is applicable to direct-drive wind and energy storage systems with back-to-back converters as grid-connected interfaces. When the grid is disturbed and converter-assisted frequency regulation is required, the proposed control strategy will mobilize the wind turbine rotor and energy storage module to participate in the system's inertia response process, providing equivalent inertia for the system, ensuring system frequency stability, increasing the power generation of grid-connected wind turbine systems, and reducing the frequency regulation cost of grid-connected wind turbine systems.

[0068] See Figure 1 This embodiment mainly consists of a wind turbine, a permanent magnet synchronous generator, a back-to-back converter, an energy storage module, an energy storage converter, and a load component. The direct-drive wind-storage system delivers power to the load and can provide necessary frequency regulation power when the load is disturbed. The specific method is as follows:

[0069] S1. The machine-side converter adopts a constant voltage control strategy to generate a DC capacitor voltage command value U. dcref ;

[0070] S2, d-axis current setpoint i of the machine-side converter rd0 The value is 0, and the q-axis current command value is i. rq0 Based on the DC capacitor voltage command value U in step S1dcref and DC capacitor voltage U dc After the difference is calculated, the q-axis current command value i is obtained through the proportional-integral (PI) control module. rq0 ;

[0071] S3. Based on the current command value i in step S2 rd0 and instruction value i rq0 The PWM control signal for the machine-side converter is generated by the current loop;

[0072] See Figure 2 The generator-side converter uses constant voltage control, and the DC capacitor voltage command value U dcref and DC capacitor voltage U dc After the difference is calculated, the q-axis current command value i is generated by the proportional-integral (PI) control module. rq0 d-axis current command value i rd0 The value is set to 0, and finally a PWM control signal is generated through the current loop control.

[0073] S4. The grid-side converter adopts droop control and provides an active power reference value P. wref The grid-side power angle θ is given based on the active-frequency control equation for droop control. The active-frequency control equation for droop control is:

[0074] ω ref =ω0+K p (P wref -P w ) ①

[0075] In the formula, ω ref ω0 is the reference value for angular frequency, and P is the rated value for angular frequency. wref P is the power reference value. w For grid-side power, K p This is the active power-frequency droop factor.

[0076] S5. Provide the reactive power reference value Q. wref The reference value U of the grid-side voltage is given based on the reactive power-voltage control equation of droop control. ref The reactive power-voltage control equation for droop control is:

[0077] U ref =U0+K q (Q wref -Q w ) ②

[0078] In the formula, U ref U0 is the voltage command value, U0 is the grid-side voltage rating, and K is the voltage command value. q Q is the reactive power-voltage droop factor. wref Q is the reactive power reference value. wThis refers to the reactive power on the grid side.

[0079] S6. Based on the reference values ​​U of the grid-side power angle θ and grid-side voltage obtained in steps S4 and S5. ref The PWM control signal for the grid-side converter is provided through voltage and current dual closed-loop control;

[0080] See Figure 3 The grid side uses droop control, with a power command P wref and grid-side power P w After subtraction, the grid-side angular frequency change Δω is obtained through the active power-frequency droop equation. Δω is then integrated to obtain the grid-side power angle θ and the voltage command value U. ref The signal is generated by equation ② and finally the grid-side converter PWM control signal is obtained through the voltage generator and the voltage and current dual closed-loop control module.

[0081] S7. The energy storage converter adopts voltage-current loop control, and the DC capacitor voltage command value U... dcref and DC capacitor voltage U dc After the difference is calculated, the proportional-integral control module generates the energy storage converter current reference value i. ESref ;

[0082] S8, Energy Storage Converter Current Reference Value i ESref and energy storage converter current i BS After the difference is inverted, the PWM control signal of the energy storage converter is obtained through the proportional-integral control module.

[0083] See Figure 4 The energy storage converter adopts voltage-current loop control, and the DC capacitor voltage command value U dcref and DC capacitor voltage U dc After the difference is calculated, the proportional-integral control module generates the energy storage converter current reference value i. ESref Then, combined with the energy storage converter current i BS After the difference is inverted, the PWM control signal of the energy storage converter is obtained through the proportional-integral control module.

[0084] The output power of the wind turbine is controlled based on the PWM control signal of the machine-side converter obtained in step S3, the PWM control signal of the grid-side converter obtained in step S6, and the PWM control signal of the energy storage converter obtained in step S8.

[0085] S9. When the wind storage system is disturbed, the rotor first provides frequency regulation support power to the DC capacitor;

[0086] S10. If the frequency deviation is less than the lower limit of the frequency threshold, the energy storage module will not be activated, and the rotor will only support the disturbance power by sacrificing its speed.

[0087] S11. If the frequency deviation is greater than the upper limit of the frequency threshold, the energy storage module is activated. The rotor and the energy storage module work together to maintain the DC voltage stability and achieve coordinated support for the DC capacitor.

[0088] See Figure 5 When the wind-storage system encounters a disturbance, the rotor first provides frequency-modulated support power to the DC capacitor. At the same time, its frequency deviation is measured. If the frequency deviation is less than the lower limit of the frequency threshold, the energy storage module is not activated, and the rotor supports the disturbance power by sacrificing its speed. If the frequency deviation is greater than the upper limit of the frequency threshold, the energy storage module is activated, and the rotor and the energy storage module work together to maintain the DC voltage stability, thus achieving coordinated support for the DC capacitor.

[0089] S12. In order to solve the instability problem of energy storage modules at the boundary of the switching threshold, a hysteresis module S is introduced into the cooperative control.

[0090] S12. When the hysteresis module S=0, it is judged as a small disturbance, the outer voltage loop does not activate, and the energy storage converter current reference value i... ESref =0;

[0091] S13. When the hysteresis module S=1, it is judged as a large disturbance, the outer voltage loop is activated, and the reference value of the energy storage converter current i is obtained through the PI circuit. ESref .

[0092] S14, Energy storage converter current reference value i ESref Energy storage converter current i ES After the difference is calculated, the PWM control waveform of the energy storage converter is generated through a PI circuit.

[0093] See Figure 6 To address the instability issue at the threshold of the energy storage module's switching action, a hysteresis module S is introduced into the coordinated control. When the hysteresis module S = 0, it is considered a small disturbance, the outer voltage loop does not activate, and the energy storage converter current reference value i... ESref =0; when the hysteresis module S=1, it is judged as a large disturbance, the outer voltage loop is activated, and the reference value of the energy storage converter current i is obtained through the PI circuit. ESref Finally, the reference value of the energy storage converter current i. ESref Energy storage converter current i ES The difference is then used to generate the PWM control waveform for the energy storage converter via a PI circuit.

[0094] In some embodiments of the present invention, the criteria for determining a large disturbance are as follows:

[0095]

[0096] Where, |Δf th h| represents the upper limit threshold for the frequency of the grid-type wind-storage system, and |Δf| represents the frequency deviation.

[0097] When the above inequality holds true, it indicates that the fluctuation of the system frequency has exceeded the predetermined safety range, and corresponding control measures need to be taken to stabilize the system frequency.

[0098] In some embodiments of the present invention, the criteria for determining small perturbations are as follows:

[0099]

[0100] Where, |Δf th l |This represents the lower frequency threshold for a grid-type wind-storage system.

[0101] In some embodiments of the present invention, the judgment logic of the hysteresis module S is as follows:

[0102]

[0103] That is, under small disturbances, S=0, and the DC voltage is maintained by the direct-drive fan rotor alone; under large disturbances, S=1, and the DC voltage is maintained by the rotor and the energy storage module together, realizing coordinated support on the DC side.

[0104] In some embodiments of the present invention, the current reference value i Esref The acquisition process is as follows:

[0105] When S=0, the outer voltage loop does not participate in the control, and the current reference value i Esref =0;

[0106] When S=1, the outer voltage loop participates in the control, and a current reference value i is generated through the PI circuit. Esref .

[0107] In some embodiments of the present invention, the PWM signal generation process of the energy storage converter is as follows:

[0108] Current reference value i ESref and energy storage converter current i ES After the difference is calculated, a PWM waveform is generated through a PI circuit to control the energy storage converter.

[0109] This embodiment also includes a parameter threshold coordinated power support strategy control system for a grid-type wind-storage system, which employs the above-mentioned method, including:

[0110] The data acquisition module is used to obtain the absolute value of the upper frequency threshold |Δf of the grid-type wind-storage system. th h |, Absolute value of the lower frequency threshold|Δf th l| Absolute value of frequency deviation |Δf| Reference value of DC capacitor voltage U dcref DC capacitor voltage U dc and energy storage converter current i ES ;

[0111] The judgment module is used to determine the magnitude of the absolute value of the frequency deviation, |Δf|, and to determine whether it is a large or small disturbance based on its magnitude.

[0112] The hysteresis module is used to control the activation of the voltage outer loop of the energy storage converter. When S is set to 0, the voltage outer loop of the energy storage module is not activated, and when S is set to 1, the voltage outer loop of the energy storage module is activated. The voltage outer loop control can be enabled or disabled by adjusting the value of S to optimize system performance and stability.

[0113] The current calculation module is used to calculate the current based on the DC capacitor voltage reference value U. dcref and DC capacitor voltage U dc The difference is used to obtain the reference value i of the energy storage converter current through the proportional-integral control module. Esref The current loop generates a PWM control signal for the energy storage converter; the system adjusts the output current of the energy storage converter to maintain DC-side voltage stability or respond to grid frequency changes.

[0114] The control module is used to control the output power of the wind turbine according to the PWM control signal of the energy storage converter. By controlling the output power of the wind turbine, it works in conjunction with the energy storage system to achieve comprehensive control of the grid frequency and DC side voltage, which helps to quickly adjust the system state when the grid frequency fluctuates or the DC side voltage deviates.

[0115] The system achieves intelligent control of the grid-type wind-storage system through the coordinated operation of its various modules. By monitoring the grid frequency and DC-side voltage in real time and adopting corresponding control strategies according to different disturbance types, the system can effectively maintain the stability of the grid frequency and DC-side voltage, thereby improving the overall performance and reliability of the system.

[0116] This embodiment also includes a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described method.

[0117] The computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0118] This embodiment also includes an electronic device, comprising:

[0119] Memory, used to store computer programs;

[0120] A processor is used to execute computer programs to implement the methods described above.

[0121] The processor can be a microprocessor, digital signal processor (DSP), microcontroller (MCU), etc. In grid-type wind and energy storage systems, processors with high performance, low power consumption and strong real-time performance are usually selected. The processor continuously reads input signals (such as grid frequency, DC voltage, energy storage converter current, etc.), executes control algorithms stored in memory, calculates control signals (such as PWM control signals, wind turbine output power adjustment signals, etc.), and outputs these control signals to the corresponding actuators (such as energy storage converter, wind turbine controller, etc.) to achieve the above method.

[0122] This embodiment also includes a computer program product, comprising a computer program that, when executed by a processor, implements the above-described method.

[0123] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0124] By coordinating the output of the wind turbine rotor and the energy storage module, different response resources are used to respond to different disturbances, ensuring system frequency safety. Furthermore, while ensuring frequency safety, the power coordination support strategy provided in this embodiment does not require significant modifications to the original control of the direct-drive wind turbine. Only a hysteresis module needs to be introduced into the turbine-side converter and the energy storage converter. This minimizes the economic investment required in the modification of the direct-drive wind-storage system, demonstrating practical engineering and economic value.

[0125] This embodiment uses the MATLAB experimental platform to verify the effectiveness of the proposed frequency control. Figure 1 The grid-connected interface diagram of the grid-type direct-drive wind-storage system shown is used as the test object in this embodiment. To verify the technical solution, this embodiment compares the turbine-side constant voltage control strategy and the capacitor virtual inertia control strategy proposed in this invention under different operating conditions, provided that droop control is adopted on the grid side. The compared operating conditions include: the energy storage module does not participate in frequency regulation (Case I), the energy storage module participates in frequency regulation throughout (Case II), and the proposed collaborative power support strategy (Case III).

[0126] like Figure 7-13 As shown, the wind-storage system experienced random disturbances, including both large and small disturbances. Figure 7-8 As shown in the figure, the system frequency and grid-side output power waveforms under three control methods are consistent. The results show that the system frequency and grid-side output power are consistent under the three control methods. This is because the grid-side control strategies of the three control methods are consistent. However, for wind-storage systems that are constructed by the grid side, their output power depends on the grid-side load and its grid construction control method.

[0127] like Figure 9 The figure shows the rotor speed waveforms of the direct-drive wind turbine under three control conditions. The results indicate that: when the energy storage module does not participate in frequency regulation, changes in grid load can only be responded to by the rotor, which causes large fluctuations in rotor speed and damages the rotor's mechanical structure; when the energy storage module participates in frequency regulation throughout the process, since the energy storage module's response speed is faster than the rotor's, changes in grid load are all responded to by the energy storage module, and the rotor speed remains unchanged; and for the proposed coordinated power support control, the rotor speed does not exhibit large fluctuations.

[0128] like Figure 10 The figure shows the output power waveforms of the energy storage module under three control conditions. The results show that: when the energy storage module does not participate in frequency regulation, the energy storage module has no output power; when the energy storage module participates in frequency regulation throughout the process, since the response speed of the energy storage module is faster than that of the rotor, the changes in grid load are all responded to by the energy storage module, resulting in a large number of charge and discharge cycles for the energy storage module; and for the proposed coordinated power support control, the number of charge and discharge cycles for the energy storage module is small.

[0129] like Figure 11 The figure shows the state-of-charge (SOC) waveforms of the energy storage module under three control conditions. The results indicate that: when the energy storage module does not participate in frequency regulation, the SOC of the energy storage module remains unchanged; when the energy storage module participates in frequency regulation throughout the process, since the response speed of the energy storage module is faster than that of the rotor, the changes in grid load are all responded to by the energy storage module, resulting in frequent changes in the SOC of the energy storage module; and for the proposed coordinated power support control, the number of charge-discharge cycles of the energy storage module is less, and the changes in the SOC are also smaller.

[0130] like Figure 12-13 As shown in the figure, the number of energy storage responses and the statistics of the number of responses under the three control methods are compared. The results show that under the proposed collaborative power support strategy, since the energy storage module only responds to large disturbances, the collaborative control can effectively reduce the number of actions of the energy storage module and improve its service life when facing the same disturbance.

[0131] The comprehensive simulation analysis results show that while the frequency regulation of energy storage modules can be reduced when energy storage does not participate, the wind turbine rotor will experience significant fluctuations under large disturbances, damaging the rotor's mechanical structure. While the frequency regulation of energy storage throughout the process can reduce rotor speed fluctuations, the frequent charging and discharging of the energy storage module will shorten its lifespan. The collaborative power support control proposed in this patent, which introduces a hysteresis module, allows the wind turbine rotor to respond to system frequency changes under small disturbances, and the wind turbine rotor and energy storage module to respond collaboratively to system frequency changes under large disturbances. This effectively reduces pulsation and wear on the direct-drive wind turbine rotor and the negative effects of frequent charging and discharging of the energy storage module, thus improving the lifespan of the energy storage module.

[0132] The above description is only some specific embodiments of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0133] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A parameter threshold coordinated power support method for a grid-type wind-storage system, characterized in that, Includes the following steps: Obtain the upper frequency threshold |Δf of the grid-type wind-storage system th h |、Frequency lower limit threshold|Δf th l |and frequency deviation|Δf|; Based on the upper frequency threshold |Δf th h The magnitude of the frequency deviation |Δf| determines whether the load disturbance is a large disturbance and determines the S-state value of the hysteresis module; Based on the lower frequency threshold |Δf th l The magnitude of the frequency deviation |Δf| is used to determine whether the load disturbance is a small disturbance and to determine the S-state value of the hysteresis module; Obtain the S-state value of the hysteresis module, and the reference value U of the DC capacitor voltage of the energy storage converter voltage loop parameter. dcref and DC capacitor voltage U dc ; The response strategy is determined based on the state value of the hysteresis module. During small disturbances, S=0, the outer voltage loop does not participate in the control, and only the inner current loop controls the energy storage converter, generating the energy storage converter current reference value i. ESref ; The response strategy is determined based on the state value of the hysteresis module. During large disturbances, S=1, the outer voltage loop participates in the control, and a reference value i for the energy storage converter current is generated. ESref ; Obtain the current i of the energy storage converter ES ; According to the current reference value i ESref and energy storage converter current i ES After the difference is calculated, a PWM waveform is generated through a PI circuit to control the energy storage converter. The current reference value i Esref The acquisition process is as follows: When S=0, the outer voltage loop does not participate in the control, and the current reference value i Esref =0; When S=1, the outer voltage loop participates in the control, generating a current reference value i through the PI circuit. Esref .

2. The parameter threshold coordinated power support method for a grid-type wind-storage system according to claim 1, characterized in that, The criteria for determining the large disturbance are as follows: (1)。 3. The parameter threshold coordinated power support method for a grid-type wind-storage system according to claim 1, characterized in that, The criteria for determining the small disturbance are as follows: (2)。 4. The parameter threshold coordinated power support method for a grid-type wind-storage system according to claim 1, characterized in that, The judgment logic of the hysteresis module S is as follows: (3) That is, under small disturbances, S=0, and the DC voltage is maintained by the direct-drive fan rotor alone; under large disturbances, S=1, and the DC voltage is maintained by the rotor and the energy storage module together, realizing coordinated support on the DC side.

5. The parameter threshold coordinated power support method for a grid-type wind-storage system according to claim 1, characterized in that, The process of generating the PWM signal for the energy storage converter is as follows: Current reference value i ESref and energy storage converter current i ES After differential operation, a PWM waveform is generated through a PI circuit to control the energy storage converter.

6. A parameter threshold coordinated power support control system for a grid-type wind-storage system, characterized in that, The method described in any one of claims 1-5 includes: The data acquisition module is used to obtain the absolute value of the upper frequency threshold |Δf of the grid-type wind-storage system. th h |, Absolute value of the lower frequency threshold|Δf th l | Absolute value of frequency deviation |Δf | Reference value of DC capacitor voltage U dcref DC capacitor voltage U dc and energy storage converter current i ES ; The judgment module is used to determine the magnitude of the absolute value of the frequency deviation, |Δf|, and to determine whether it is a large or small disturbance based on its magnitude. The hysteresis module is used to control the activation of the outer voltage loop of the energy storage converter. When S is set to 0, the outer voltage loop of the energy storage module is not activated, and when S is set to 1, the outer voltage loop of the energy storage module is activated. The current calculation module is used to calculate the current based on the DC capacitor voltage reference value U. dcref and DC capacitor voltage U dc The difference is used to obtain the reference value i of the energy storage converter current through the proportional-integral control module. Esref And the current loop generates the PWM control signal for the energy storage converter; The control module is used to control the output power of the wind turbine based on the PWM control signal of the energy storage converter.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method as described in any one of claims 1-5.

8. An electronic device, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the method as described in any one of claims 1-5.

9. A computer program product, characterized in that, Includes a computer program that, when executed by a processor, implements the method as described in any one of claims 1-5.

Images