Parameter threshold value collaborative power supporting method and system of network construction type wind storage system

Abstract

The invention relates to the technical field of power system frequency control, in particular to a parameter threshold collaborative power support method and system for a network-forming type wind storage system, and the method comprises the steps: when the system frequency deviation is smaller than the lower limit of a frequency threshold, determining that the disturbance is small, an energy storage module does not respond, and the DC voltage is maintained stable only by a rotor; and when the disturbance causes the frequency deviation of the wind storage system to be greater than the upper limit of the frequency threshold, the disturbance is judged to be large disturbance, and at the moment, the rotor and the energy storage module jointly maintain the stability of the direct-current voltage to realize the collaborative support of the direct-current side. On the basis of ensuring small-range fluctuation of the rotating speed of the rotor, the charging and discharging times of the energy storage module can be reduced, the service life of the energy storage module of the wind storage system can be prolonged, the stability of the frequency of a power grid can be effectively maintained, and the economical efficiency of the grid construction type direct-driven wind storage system can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of power system frequency control, and in particular to a parameter threshold coordinated power support method and system for a grid-connected wind-storage system. Background Art

[0002] In the current situation of increasingly serious environmental pollution and increasingly scarce energy, wind power, as one of the most mature forms of new energy development and utilization technology, has a continuously increasing penetration rate in the power system. At present, most wind turbines use grid-following control, relying on the phase-locked loop to follow the frequency / phase of the AC grid voltage to achieve synchronization with the grid. It is difficult to operate stably under weak grids and does not have the ability to support the grid. Wind power systems based on grid-building control can achieve faster frequency response due to their characteristics of autonomously building frequency / phase, and have received widespread attention.

[0003] The supporting characteristics of the grid-type wind power system for the grid frequency require the frequency response resources to pay a corresponding frequency regulation price. The wind turbine rotor has a certain amount of rotational kinetic energy, which can play a good supporting role in the stability of the system frequency. However, using the rotor power for frequency regulation requires sacrificing the maximum power capacity of the wind power system, and the stored energy is limited, which weakens the frequency regulation effect to a certain extent. The energy storage system has the advantages of fast response speed and the ability to accurately track active power instructions. Through the optimized design of the control system, it can achieve fast inertia response capability and continuous active power support. Therefore, it is necessary to equip the wind farm with a certain proportion of energy storage modules.

[0004] In summary, the coordinated control principle of the grid-connected direct-drive wind-storage system with back-to-back converters as the grid-connected 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 to be 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 to be a large disturbance, and the energy storage module is activated to maintain the DC voltage stability together with the rotor to provide supporting power for the grid side; (3) On the basis of ensuring that the rotor speed does not fluctuate within a large range, the charging and discharging times of the energy storage module can be reduced, thereby increasing the service life of the energy storage module in the grid-connected direct-drive wind-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 prior art 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 parameter threshold coordinated power support method for a grid-type wind-storage system is provided, comprising:

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

[0008] According to the upper frequency threshold |Δf th h | and the frequency deviation |Δf| determine whether the load disturbance is a large disturbance and determine the S state value of the hysteresis module;

[0009] According to the frequency lower limit threshold |Δf th l | and the size of the frequency deviation |Δf|, judge whether the load disturbance is a small disturbance, and determine the S state value of the hysteresis module;

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

[0011] The response strategy is determined according to the state value of the hysteresis module. When the disturbance is small, S=0, the voltage outer loop does not participate in the control, and the energy storage converter is controlled only by the current inner loop to generate the energy storage converter current reference value i ESref ;

[0012] The response strategy is determined according to the state value of the hysteresis module. When the disturbance is large, S=1, and the voltage outer loop participates in the control to generate the energy storage converter current reference value i ESref ;

[0013] Get the energy storage converter current i ES ;

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

[0015] In some embodiments of the present invention, the judgment basis of the large disturbance is:

[0016]

[0017] In some embodiments of the present invention, the judgment basis of the small disturbance is:

[0018]

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

[0020]

[0021] That is, in the case of small disturbances, S=0, and the DC voltage is maintained stable only by the direct-drive wind turbine rotor; in the case of large disturbances, S=1, and the DC voltage is maintained stable by the rotor and the energy storage module together, achieving coordinated support on the DC side.

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

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

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

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

[0026] Current reference value i ESref and the energy storage converter current i ES After the difference is made, a PWM waveform is generated through the PI link 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] Data acquisition module, used to obtain the absolute value of the frequency upper limit threshold of the grid-type wind-storage system |Δf th h |, absolute value of the lower frequency threshold |Δf th l |, absolute value of frequency deviation |Δf|, DC capacitor voltage reference value U dcref , DC capacitor voltage U dc and the energy storage converter current i ES ;

[0029] A judgment module is used to judge the magnitude of the absolute value of the frequency deviation |Δf|, and judge it as a large disturbance or a small disturbance according to its magnitude;

[0030] The hysteresis module is used to control the input 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 input, and when S is set to 1, the voltage outer loop of the energy storage module is input;

[0031] Current calculation module for DC capacitor voltage reference value U dcref and DC capacitor voltage U dc The difference between the current reference value i of the energy storage converter is obtained through the proportional integral control module. Esref And generate the energy storage converter PWM control signal through the current loop;

[0032] The control module is used to control the output power of the fan according to the PWM control signal of the energy storage converter.

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

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

[0035] Memory for storing computer programs;

[0036] A processor is used to execute the computer program to implement the method as described in any one of the first aspect or the second aspect.

[0037] According to a fifth aspect of the present invention, there is further provided a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the method according to any one of the first aspect or the second aspect is implemented.

[0038] The beneficial effects of the present invention are as follows: the present invention distinguishes large and small disturbances by frequency threshold, and adds a hysteresis module to the coordination criterion. In case of small disturbance, the direct-drive wind turbine rotor provides all the supporting power; in case of large disturbance, the energy storage module operates and maintains the DC voltage stability together with the rotor, providing supporting power for the DC capacitor, realizing the coordinated support of the rotor and the energy storage module to the DC side of the grid-type direct-drive wind storage system. The present invention can reduce the number of charge and discharge times of the energy storage module on the basis of ensuring that the rotor speed does not fluctuate within a large range, thereby increasing the service life of the energy storage module in the grid-type direct-drive wind storage system, which is beneficial to the long-term stable operation of the wind storage system; for the frequency control of the power system, the present invention can not only effectively maintain the stability of the grid frequency, but also the economy of the grid-type direct-drive wind storage system, and can also improve the reliability and life of the energy storage module under the premise that the direct-drive wind turbine rotor speed fluctuation is not large, and has practical engineering application value and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0041] Figure 2The control strategy of the machine-side converter in the embodiment of the present invention;

[0042] Figure 3 The grid-side converter control strategy in the embodiment of the present invention;

[0043] Figure 4 The energy storage converter control strategy in the embodiment of the present invention;

[0044] Figure 5 It is the synergistic mechanism in the embodiment of the present invention;

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

[0046] Figure 7 The system frequency waveforms are compared in three cases: parameter threshold coordinated power control strategy under random disturbance, energy storage module not responding to frequency change, and energy storage module responding entirely;

[0047] Figure 8 The grid-side output power waveforms are compared under three conditions: parameter threshold coordinated power control strategy under random disturbance, energy storage module not responding to frequency change, and energy storage module responding entirely;

[0048] Fig. 9 The waveforms of the rotor speed of the direct-drive wind turbine are compared under three conditions: the parameter threshold coordinated power control strategy under random disturbance, the energy storage module not responding to the frequency change, and the energy storage module responding entirely;

[0049] Fig.10 The power comparison of energy storage modules under three conditions: parameter threshold coordinated power control strategy under random disturbance, energy storage module not responding to frequency change, and energy storage module responding entirely;

[0050] Fig.11 Comparison of battery state of charge waveforms under three conditions: parameter threshold coordinated power control strategy under random disturbance, energy storage module not responding to frequency change, and energy storage module responding entirely;

[0051] Fig.12 Comparison of energy storage response times in three cases: parameter threshold coordinated power control strategy under random disturbance, energy storage module not responding to frequency change, and energy storage module responding entirely;

[0052] Fig.13 Statistics of energy storage response times in three cases: parameter threshold coordinated power control strategy under random disturbance, energy storage module not responding to frequency change, and all energy storage modules responding in accordance with the embodiment of the present invention;

[0053] Fig.14It is a flow chart of the parameter threshold coordinated power support method of the grid-type wind-storage system in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

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

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

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

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

[0059] According to the upper frequency threshold |Δf th h | and the frequency deviation |Δf| determine whether the load disturbance is a large disturbance and determine the S state value of the hysteresis module;

[0060] According to the frequency lower limit threshold |Δf th l | and the size of the frequency deviation |Δf|, judge whether the load disturbance is a small disturbance, and determine the S state value of the hysteresis module;

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

[0062] The response strategy is determined according to the state value of the hysteresis module. When the disturbance is small, S=0, the voltage outer loop does not participate in the control, and the energy storage converter is controlled only by the current inner loop to generate the energy storage converter current reference value i ESref ;

[0063] The response strategy is determined according to the state value of the hysteresis module. When the disturbance is large, S=1, and the voltage outer loop participates in the control to generate the energy storage converter current reference value i ESref ;

[0064] Get the energy storage converter current i ES ;

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

[0066] The parameter threshold collaborative 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 output in response to system frequency changes. When the grid-type direct-drive wind-storage system encounters a disturbance, the rotor first provides frequency modulation support power for 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 enabled, and only the direct-drive wind turbine rotor supports the disturbance power by sacrificing the speed; if the frequency deviation is greater than the upper limit of the frequency threshold, the energy storage module is enabled, and the direct-drive wind turbine rotor and the energy storage module jointly maintain the DC voltage stability to achieve collaborative support for the DC capacitor.

[0067] The control method proposed in the present invention is applicable to a direct-drive wind-storage system with a back-to-back converter as the grid-connected interface. When the power grid is disturbed and the converter is required to assist in frequency regulation, the proposed control strategy will respectively mobilize the wind turbine rotor and the energy storage module to participate in the inertia response process of the system, provide equivalent inertia for the system, ensure the stability of the system frequency, increase the power generation of the grid-type wind turbine system, and reduce the frequency regulation cost of the grid-type wind turbine system.

[0068] See also Figure 1 This embodiment is mainly composed of a wind turbine, a permanent magnet synchronous generator, a back-to-back converter, an energy storage module, an energy storage converter, a load part, etc. The direct-drive wind storage system transmits power to the load and can provide the necessary frequency modulation 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, the given value of the d-axis current of the machine-side converter i rd0 The value is 0, and the q-axis current command value i rq0 According to the DC capacitor voltage command value U in step S1dcref and DC capacitor voltage U dc After the difference is made, the q-axis current command value i is obtained through the control module based on proportional integral PI rq0 ;

[0071] S3, according to the current command value i in step S2 rd0 and instruction value i rq0 The PWM control signal of the machine-side converter is generated by the current loop;

[0072] See also Figure 2 The machine-side converter adopts constant voltage control, and the DC capacitor voltage command value U dcref and DC capacitor voltage U dc After the difference is made, the q-axis current command value i is generated through the control module based on proportional integral PI rq0 , d-axis current command value i rd0 The value is 0, and finally a PWM control signal is generated through current loop control.

[0073] S4, the grid-side converter adopts droop control to give the active power reference value P wref , the grid-side power angle θ is given according to the active power-frequency control equation of droop control. The active power-frequency control equation of droop control is:

[0074] ω ref =ω0+K p (P wref -P w ) ①

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

[0076] S5. Give reactive power reference value Q wref According to the reactive power-voltage control equation of droop control, the reference value U of the grid voltage is given. ref , the reactive power-voltage control equation of droop control is:

[0077] U ref =U0+K q (Q wref -Q w ) ②

[0078] Where U ref is the voltage command value, U0 is the grid-side voltage rated value, K q is the reactive power-voltage droop coefficient, Q wref is the reactive power reference value, Q wis the grid-side reactive power.

[0079] S6: The grid-side power angle θ and the reference value U of the grid-side voltage obtained in steps S4 and S5 ref , through the voltage and current double closed-loop control, the PWM control signal of the grid-side converter is given;

[0080] See also Figure 3 , the grid side adopts droop control, the power command P wref and grid-side power P w After the difference is made, the grid-side angular frequency change Δω is obtained through the active power-frequency droop equation. Δω is used to obtain the grid-side power angle θ through the integral link, and the voltage command value U ref Generated by formula ②, the grid-side converter PWM control signal is finally obtained through the voltage generator and the voltage-current dual closed-loop control module;

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

[0082] S8, energy storage converter current reference value i ESref and the energy storage converter current i BS After the difference is inverted, the PWM control signal of the energy storage converter is obtained through a control module based on proportional integration;

[0083] See also Figure 4 The energy storage converter adopts voltage and current loop control, and the DC capacitor voltage command value U dcref and DC capacitor voltage U dc After the difference is made, the energy storage converter current reference value i is generated through the proportional-integral control module ESref , and then the energy storage converter current i BS After the difference is inverted, the PWM control signal of the energy storage converter is obtained through a control module based on proportional integration;

[0084] Control the output power of the wind turbine according to 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 modulation support power for the DC capacitor;

[0086] S10, if the frequency deviation is less than the lower limit of the frequency threshold, the energy storage module is not enabled, and the rotor only supports the disturbance power by sacrificing the speed;

[0087] S11. If the frequency deviation is greater than the upper frequency threshold, the energy storage module is enabled, and the rotor and the energy storage module jointly maintain the DC voltage stability to achieve collaborative support for the DC capacitor;

[0088] See also Figure 5 When the wind storage system encounters a disturbance, the rotor first provides frequency modulation support power for the DC capacitor. At the same time, the frequency deviation is measured. If the frequency deviation is less than the lower limit of the frequency threshold, the energy storage module is not enabled, and the rotor only supports the disturbance power by sacrificing the speed; if the frequency deviation is greater than the upper limit of the frequency threshold, the energy storage module is enabled, and the rotor and the energy storage module jointly maintain the DC voltage stability to achieve coordinated support for the DC capacitor;

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

[0090] S12, hysteresis module S = 0, it is judged as a small disturbance, the voltage outer loop is not put into action, 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 voltage outer loop is put into action, and the energy storage converter current reference value i is obtained through the PI link ESref .

[0092] S14, energy storage converter current reference value i ESref Energy storage converter current i ES After making the difference, the PWM control waveform of the energy storage converter is generated through the PI link;

[0093] See also Figure 6 In order to solve the instability problem of the energy storage module at the boundary of the switching threshold, the hysteresis module S is introduced in the coordinated control. When the hysteresis module S = 0, it is judged as a small disturbance, the voltage outer loop is not put into action, 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 voltage outer loop is put into action, and the energy storage converter current reference value i is obtained through the PI link ESref The final energy storage converter current reference value i ESref Energy storage converter current i ES After the difference is made, the PWM control waveform of the energy storage converter is generated through the PI link.

[0094] In some embodiments of the present invention, the basis for determining a large disturbance is:

[0095]

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

[0097] When the above inequality holds true, it means 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 basis for determining a small disturbance is:

[0099]

[0100] Where |Δf th l | is the lower frequency threshold of the grid-type wind-storage system.

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

[0102]

[0103] That is, in the case of small disturbances, S=0, and the DC voltage is maintained stable only by the direct-drive wind turbine rotor; in the case of large disturbances, S=1, and the DC voltage is maintained stable by the rotor and the energy storage module together, achieving coordinated support on the DC side.

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

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

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

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

[0108] Current reference value i ESref and the energy storage converter current i ES After the difference is made, a PWM waveform is generated through the PI link 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 adopts the above method, including:

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

[0111] A judgment module is used to judge the magnitude of the absolute value of the frequency deviation |Δf|, and judge it as a large disturbance or a small disturbance according to its magnitude;

[0112] The hysteresis module is used to control the input 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 input, and when S is set to 1, the voltage outer loop of the energy storage module is input; the voltage outer loop control is enabled or disabled by adjusting the value of S to optimize system performance and stability;

[0113] Current calculation module for DC capacitor voltage reference value U dcref and DC capacitor voltage U dc The difference between the current reference value i of the energy storage converter is obtained through the proportional integral control module. Esref The energy storage converter PWM control signal is generated through the current loop; the system adjusts the output current of the energy storage converter to maintain the 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 inverter. By controlling the output power of the wind turbine, it works in coordination with the energy storage system to achieve comprehensive control of the grid frequency and DC side voltage, which helps to quickly adjust the system status when the grid frequency fluctuates or the DC side voltage deviates.

[0115] The system realizes intelligent control of the grid-type wind storage system through the coordinated work of various modules. By real-time monitoring of the grid frequency and DC side voltage, and taking corresponding control strategies according to different disturbance types, the system can effectively maintain the stability of the grid frequency and DC side voltage, and improve the overall performance and reliability of the system.

[0116] This embodiment also includes a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the above method is implemented.

[0117] Among them, 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, disk or optical disk.

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

[0119] Memory for storing computer programs;

[0120] A processor is used to execute a computer program to implement the above method.

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

[0122] This embodiment also includes a computer program product, including a computer program, and the computer program implements the above method when executed by a processor.

[0123] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0124] By coordinating the output of the wind turbine rotor and the energy storage module, different response resources respond under different disturbances to ensure system frequency safety. In addition, under the premise of ensuring frequency safety, the power coordination support strategy provided by this embodiment does not require too many changes to the original control of the direct-drive wind turbine. It only needs to introduce a hysteresis module in the machine-side converter and the energy storage converter. In the process of transforming the direct-drive wind storage system, it does not require too much economic investment, and has practical engineering application value and economic value.

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

[0126] like Figure 7-13 As shown in , the wind-storage system experiences random disturbances including large disturbances 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. This is because the grid-side control strategies of the three control methods are consistent. For the wind-storage system that realizes grid construction by the grid side, its output power depends on the grid-side load and its grid construction control method.

[0127] like Fig. 9 As shown in the figure, the rotor speed waveforms of the direct-drive wind turbine under three types of control are shown. The results show that: when the energy storage module does not participate in frequency modulation, the load changes on the grid side can only be responded to by the rotor, which will cause a large range of fluctuations in the rotor speed and damage the mechanical structure of the rotor; when the energy storage module participates in frequency modulation throughout the process, since the response speed of the energy storage module is faster than that of the rotor, the load changes on the grid side are all responded to by the energy storage module, and the rotor speed does not change; and for the proposed coordinated power support control, the rotor speed does not fluctuate over a large range.

[0128] like Fig.10 As shown in the figure, the output power waveforms of the energy storage module under three types of control are shown. 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 load changes on the grid side are all responded to by the energy storage module, and the energy storage module has more charge and discharge times; while for the proposed coordinated power support control, the energy storage module has fewer charge and discharge times.

[0129] like Fig.11 As shown in the figure, the battery state of charge waveforms of the energy storage module under three types of control are shown. The results show that: when the energy storage module does not participate in frequency regulation, the state of charge of the energy storage module does not change; 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 load changes on the grid side are all responded to by the energy storage module, and the state of charge of the energy storage module changes frequently; and for the proposed coordinated power support control, the energy storage module has fewer charge and discharge times, and the change of state of charge is also small.

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

[0131] The comprehensive simulation analysis results show that: when energy storage does not participate in frequency modulation, the number of energy storage module actions can be reduced, but the fan rotor will fluctuate over a large range when there is a large disturbance, causing damage to the mechanical structure of the rotor; when energy storage participates in frequency modulation throughout the process, the fluctuation of the rotor speed can be reduced, but the frequent charging and discharging of the energy storage module will reduce its life. The collaborative power support control proposed in this patent introduces a hysteresis module, in which the fan rotor responds to system frequency changes in small disturbances, and in large disturbances, the fan rotor and energy storage module respond to system frequency changes in a coordinated manner. At the same time, it effectively reduces the pulsation and wear of the direct-drive fan rotor and the negative problems caused by the frequent charging and discharging of the energy storage module, and increases the service life of the energy storage module.

[0132] The above are only some specific embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0133] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A parameter threshold coordinated power support method for a grid-type wind-storage system, characterized in that: The steps include: Obtain the frequency upper limit threshold |Δf of the grid-type wind-storage system th h |, frequency lower limit threshold |Δf th l | and frequency deviation |Δf|; According to the upper frequency threshold |Δf th h | and the frequency deviation |Δf| determine whether the load disturbance is a large disturbance and determine the S state value of the hysteresis module; According to the frequency lower limit threshold |Δf th l | and the size of the frequency deviation |Δf|, judge whether the load disturbance is a small disturbance, and determine the S state value of the hysteresis module; Get the S state value of the hysteresis module, the DC capacitor voltage reference value U of the energy storage converter voltage loop parameter dcref and DC capacitor voltage U dc ; The response strategy is determined according to the state value of the hysteresis module. When the disturbance is small, S=0, the voltage outer loop does not participate in the control, and the energy storage converter is controlled only by the current inner loop to generate the energy storage converter current reference value i ESref ; The response strategy is determined according to the state value of the hysteresis module. When the disturbance is large, S=1, and the voltage outer loop participates in the control to generate the energy storage converter current reference value i ESref ; Get the energy storage converter current i ES ; According to the current reference value i ESref and the energy storage converter current i ES After the difference is made, a PWM waveform is generated through the PI link to control the energy storage converter.

2. The parameter threshold coordinated power support method of the grid-type wind-storage system according to claim 1 is characterized in that: The judgment basis of the large disturbance is:

3. The parameter threshold coordinated power support method of the grid-type wind-storage system according to claim 1 is characterized in that: The judgment basis of the small disturbance is:

4. The parameter threshold coordinated power support method of the grid-type wind-storage system according to claim 1 is characterized in that: The judgment logic of the hysteresis module S is: That is, in the case of small disturbances, S=0, and the DC voltage is maintained stable only by the direct-drive wind turbine rotor; in the case of large disturbances, S=1, and the DC voltage is maintained stable by the rotor and the energy storage module together, achieving coordinated support on the DC side.

5. The parameter threshold coordinated power support method of the grid-type wind-storage system according to claim 1 is characterized in that: The current reference value i Esref The acquisition process is: When S=0, the voltage outer loop does not participate in the control, and the current reference value i Esref =0; When S=1, the voltage outer loop participates in the control and generates the current reference value i through the PI link. Esref .

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

7. A parameter threshold coordinated power support control system for a grid-type wind storage system, characterized in that: The method according to any one of claims 1 to 6 is adopted, comprising: Data acquisition module, used to obtain the absolute value of the frequency upper limit threshold of the grid-type wind-storage system |Δf th h |, absolute value of the lower frequency threshold |Δf th l |, absolute value of frequency deviation |Δf|, DC capacitor voltage reference value U dcref , DC capacitor voltage U dc and the energy storage converter current i ES ; A judgment module is used to judge the magnitude of the absolute value of the frequency deviation |Δf|, and judge it as a large disturbance or a small disturbance according to its magnitude; The hysteresis module is used to control the input 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 input, and when S is set to 1, the voltage outer loop of the energy storage module is input; Current calculation module for DC capacitor voltage reference value U dcref and DC capacitor voltage U dc The difference between the current reference value i of the energy storage converter is obtained through the proportional integral control module. Esref And generate the energy storage converter PWM control signal through the current loop; The control module is used to control the output power of the fan according to the PWM control signal of the energy storage converter.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

9. An electronic device, characterized in that: include: Memory for storing computer programs; A processor, configured to execute the computer program to implement the method according to any one of claims 1 to 6.

10. A computer program product, characterized in that The method comprises a computer program, which implements the method according to any one of claims 1 to 6 when being executed by a processor.

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