A fan frequency support method, apparatus, and system

Abstract

This invention discloses a wind turbine frequency support method, device, and system, belonging to the field of power system control technology. The method includes: when a frequency fault occurs in a wind farm, the dominant wind turbine receives the frequency signal and participates in frequency support according to the integrated inertia control; one wind turbine in the wind farm is designated as the dominant wind turbine, and the remaining wind turbines are non-dominant wind turbines; the real-time changing consistency state variables of each wind turbine are calculated using the real-time rotational speed, initial rotational speed, and minimum rotational speed limit corresponding to each wind turbine; and the consistency state variables of adjacent wind turbines are exchanged, so that each non-dominant wind turbine senses the frequency change received by the dominant wind turbine and follows the frequency regulation action of the dominant wind turbine to participate in frequency support until the preset frequency support time ends. This invention designs consistency state variables to enable the exchange of consistency index information among wind turbines, thereby realizing the following of the frequency support actions of the dominant wind turbine by the non-dominant wind turbines in the wind farm and achieving a reasonable allocation of frequency support power.

Description

Technical Field

[0001] This invention belongs to the field of power system control technology, and more specifically, relates to a wind turbine frequency support method, device and system. Background Technology

[0002] In recent years, wind farms have become a hot topic in clean energy. However, since wind farms cannot directly respond to system frequency deviations, and with the increasing penetration of wind power, traditional synchronous motors are being replaced, system inertia is decreasing, and system frequency stability will face challenges. Therefore, to ensure stable system operation, wind farms need to have the ability to actively regulate system frequency.

[0003] To reduce wind curtailment, wind farms actively participate in frequency support primarily by controlling rotor speed to release rotor kinetic energy, achieved through an additional frequency support controller. However, due to the influence of geographical distribution and wind speed and direction, wind turbines at different locations within the wind farm experience varying wind speeds and thus different rotational speeds, resulting in varying frequency support capabilities. If uniform control is applied to the turbines within the farm, such as... Figure 1 As shown, wind turbines 1 and 2, which have higher wind speeds and thus greater frequency support capabilities, have lower output and slower speeds. However, wind turbines 3, 4, and 5, which have lower wind speeds, have excessive output, causing their speeds to drop to dangerous levels and triggering speed protection mechanisms, leading to premature withdrawal from frequency support. This demonstrates that uniform control cannot fully utilize the frequency support capabilities of all wind turbines and may threaten the operational stability of the wind farm. Existing wind turbine frequency support control mainly falls into two categories: 1. A distributed control strategy for the wind farm, where each turbine participates in frequency support through integrated inertia control. 2. A centralized control strategy for the wind farm, where the frequency support capabilities of each turbine are calculated, and the control center issues commands to allocate frequency support power to each turbine.

[0004] Since existing control strategies only consider the safety of wind turbines, they may not be able to fully utilize the frequency regulation capabilities of wind farms and achieve reasonable power allocation; or they may adopt centralized control strategies, which have high requirements for communication reliability, and the frequency support effect may be affected by communication delays. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a wind turbine frequency support method, apparatus, and system, the purpose of which is to design a consistency state quantity to enable the exchange of consistency indices among wind turbines. x i Information is used to enable non-dominant wind turbines in a wind farm to follow the frequency support actions of the dominant wind turbines, so that each wind turbine is in a similar state during the frequency support process, thereby achieving a reasonable distribution of frequency support power, raising the minimum frequency point, and thus solving the technical problem of unbalanced wind turbine power distribution in existing wind farms.

[0006] To achieve the above objectives, according to one aspect of the present invention, a wind turbine frequency support method is provided, comprising:

[0007] S1: When a frequency fault occurs at the wind farm, the main wind turbine receives the frequency signal. f The frequency support is controlled by the comprehensive inertia control; one wind turbine in the wind farm is the dominant wind turbine WT1, and the rest of the wind turbines are non-dominant wind turbines;

[0008] S2: Utilize the real-time rotational speed of each of the aforementioned fans. oh r,i Initial speed oh r,i0 and minimum speed limit oh r,min Calculate the WT of each of the aforementioned wind turbines i Real-time changing consistent state quantity x i ; i Indicates the fan number;

[0009] S3: Control the consistency of state variables of each adjacent fan. x i The exchange allows each of the non-dominant fans to sense the frequency change received by the dominant fan, and thus follow the frequency adjustment action of the dominant fan to participate in frequency support until the preset frequency support time ends.

[0010] In one embodiment, S2 includes:

[0011] Using formula Calculate the uniformity state variables of each of the aforementioned wind turbines. x i .

[0012] In one embodiment, S3 includes:

[0013] S31: Control the consistency of state variables of each adjacent fan. x i The exchange enables each of the non-dominant wind turbines to sense the state changes of adjacent wind turbines, wherein the wind turbines adjacent to the dominant wind turbines transmit the frequency changes received by the dominant wind turbines to the other non-dominant wind turbines.

[0014] S32: Each of the aforementioned non-dominant wind turbines adjusts its instantaneous stator power according to the consistency variable of its adjacent wind turbines. P si This allows for speed control, enabling each of the non-dominant fans to follow the frequency modulation action of the dominant fan and participate in frequency support.

[0015] In one embodiment, S32 includes:

[0016] Using formula Calculate the instantaneous stator power of each of the aforementioned non-dominant wind turbines. P si This allows for the control of the rotational speed of each of the non-dominant fans;

[0017] in, k opt This represents the tracking coefficient in the maximum power point tracking curve equation; the main fan corresponds to L i For 1, each of the aforementioned non-dominant wind turbines L i =0; P x,i ( t () indicates the state reference power value. P w,i ( t ) represents the combined inertia power value.

[0018] In one embodiment, the state reference power value P x,i ( t ) is represented as:

[0019] ;in, k P,i , k I,i These are the proportion and integral coefficient of the state difference between each wind turbine and its neighboring wind turbines.

[0020] In one embodiment, the combined inertia power value P w,i ( t ) is represented as:

[0021] ; k wdr,i For wind turbine i The droop coefficient, k win,i For wind turbine i The coefficient of inertia, f d represents the system frequency deviation. f / d t This represents the rate of change of frequency.

[0022] In one embodiment, the wind turbine frequency support method further includes:

[0023] Before and after the start of wind turbine frequency support, the WT values ​​of each wind turbine are... i Torque control is performed to adjust the instantaneous stator power. P si and real-time rotation speed oh r,i satisfy , k opt This represents the tracking coefficient in the maximum power point tracking curve equation.

[0024] According to another aspect of the present invention, a wind turbine frequency support device is provided for performing the wind turbine frequency support method, comprising:

[0025] The first control module is used to receive frequency signals from the main wind turbine when a frequency fault occurs at the wind farm. f The frequency support is controlled by the comprehensive inertia control; one wind turbine in the wind farm is the dominant wind turbine WT1, and the rest of the wind turbines are non-dominant wind turbines;

[0026] The data processing module is used to utilize the real-time rotational speed of each of the aforementioned wind turbines. oh r,i Initial speed oh r,i0 and minimum speed limit oh r,min Calculate the WT of each of the aforementioned wind turbines i Real-time changing consistent state quantity x i ; i Indicates the fan number;

[0027] The second control module is used to control the consistency of state variables of each adjacent wind turbine. x i The exchange allows each of the non-dominant fans to sense the frequency change received by the dominant fan, and thus follow the frequency adjustment action of the dominant fan to participate in frequency support until the preset frequency support time ends.

[0028] According to another aspect of the present invention, a wind turbine frequency support system is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described method.

[0029] According to another aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0030] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0031] (1) This invention enables only the dominant wind turbines in the wind farm to receive the system frequency signal, while non-dominant wind turbines only need to exchange consistency state variables with neighboring wind turbines. x i This information allows for the tracking of the main fan's frequency regulation actions, reducing system communication load and avoiding the impact of communication delays on frequency support performance.

[0032] (2) This invention achieves the desired state reference power value for non-dominant fans by ensuring that the reference power value meets the requirements. Among them, the consistency state quantity This allows the output of non-dominant wind turbines to vary according to the status changes of neighboring wind turbines, avoiding the problem of unreasonable power distribution under a uniform control strategy and maximizing the utilization of the wind farm's frequency support capacity.

[0033] (3) The present invention sets the frequency support time according to the preset scenario, thereby avoiding the problem that the minimum point of the system frequency cannot be effectively improved due to the frequency support time being set too short, and at the same time avoiding the problem that the fan speed will drop below the safety threshold due to the frequency support time being set too long. Attached Figure Description

[0034] Figure 1 A schematic diagram illustrating the unreasonable power distribution caused by the existing wind turbine frequency support strategy;

[0035] Figure 2 This is a schematic diagram of a wind turbine frequency support control method provided in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of a wind turbine frequency support control method according to an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of a four-unit, two-zone power system with an onshore wind farm, provided in an embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram of information exchange between wind turbines according to an embodiment of the present invention;

[0039] Figure 6 The graph shows the system frequency changing over time under different wind turbine frequency support control strategies during an 800MW load surge disturbance, as provided in an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0041] To address the technical problem of unbalanced power distribution among wind turbines in existing wind turbine frequency support strategies, this invention provides a wind turbine frequency support control method, controller, and wind farm. The overall approach involves designing consistent state variables. This enables the exchange of consistency indicators between wind turbines. x i Information, and add status reference power values ​​to the stator power reference values ​​of each wind turbine. This enables non-dominant wind turbines in the wind farm to follow the frequency support actions of the dominant wind turbines. Due to the uniformity state quantity... x i This influence can make each wind turbine have a similar state during the frequency support process, thereby achieving a reasonable distribution of frequency support power and raising the minimum frequency point.

[0042] The technical solution provided by this invention can be applied to any type of wind farm. Without loss of generality, in the following embodiments, unless otherwise specified, the wind farm referred to is an onshore wind farm.

[0043] An embodiment of the present invention provides a wind turbine frequency support control method, comprising:

[0044] S1: When a frequency fault occurs at the wind farm, the main wind turbine receives the frequency signal. f The frequency support is controlled by the comprehensive inertia control; one wind turbine in the wind farm is the dominant wind turbine WT1, and the rest of the wind turbines are non-dominant wind turbines;

[0045] S2: Utilize the real-time rotational speed of each of the aforementioned fans. oh r,i Initial speed oh r,i0 and minimum speed limit oh r,min Calculate the WT of each of the aforementioned wind turbines i Real-time changing consistent state quantity x i ; i Indicates the fan number;

[0046] S3: Control the consistency of state variables of each adjacent fan. x iThe exchange allows each of the non-dominant fans to sense the frequency change of the dominant fan, and thus follow the frequency adjustment action of the dominant fan to participate in frequency support until the preset frequency support time ends.

[0047] Specifically, such as Figure 2 As shown, the dominant wind turbine WT1 is selected in the wind farm, and all other turbines are non-dominant turbines. At the time of the frequency fault... t b Obtain the WT of each wind turbine i Minimum speed limit oh r,min and the initial speed of each wind turbine in the field. oh r,i0 ; i This indicates the fan number. During the frequency support process, the real-time speed of each fan is acquired. oh r,i ,according to Get the WT of each wind turbine i Real-time changing consistent state quantity x i ;

[0048] Furthermore, distributed control is adopted for the wind farm. The dominant wind turbines participate in frequency support based on integrated inertia control, while non-dominant wind turbines exchange information with neighboring wind turbines and control frequency based on consistency state variables. x i Follow the main wind turbine to participate in frequency support until t b +Δ t Exit frequency support, Δ t The preset frequency support time.

[0049] In one embodiment, the wind turbine's overall inertia power value P w,i ( t )satisfy By setting the relationship between the power of the main fan and the system frequency in this way, the main fan can achieve adaptive frequency support for the degree of system frequency change. It should be noted that this is only a preferred embodiment of the present invention and should not be construed as the only limitation of the present invention. In some other embodiments of the present invention, the drooping link or inertial link of the main fan can also be omitted.

[0050] In one embodiment, the wind farm is specifically an onshore wind farm; considering both the improvement effect on the lowest frequency point of the onshore AC system and the safety of the wind turbine, the frequency support time can specifically be within the range of 11s ≤ Δ t ≤ 15s;

[0051] In one embodiment, there is no need to consider the issue of reasonable power allocation before and after the start of wind turbine frequency support. Therefore, the method further includes: before and after the start of wind turbine frequency support, adjusting the WT of each wind turbine. i Torque control is performed to adjust the instantaneous stator power. P si and real-time rotation speed oh r,i satisfy .

[0052] In one embodiment, the state of an offshore wind farm can be classified as follows: Figure 3 The three states shown are maximum power point tracking, frequency support, and speed recovery. In the frequency support state, the instantaneous stator power of the wind turbine... P si and real-time rotation speed oh r,i satisfy Constraints (Main Fan) L i =1, Non-dominant fan L i =0), in other states, the instantaneous stator power of the wind turbine P si and real-time rotation speed oh r,i satisfy The constraint relationship.

[0053] The instantaneous stator power of the wind turbine P si and real-time rotation speed oh r,i The specific expressions for the constraint relationships between them under different states are:

[0054] ;

[0055] in, t e = t b +Δ t , indicating the end time of frequency support.

[0056] The following description, using a specific application scenario, further illustrates the beneficial effects that this invention can achieve.

[0057] Figure 4 The diagram shows a four-turbine, two-zone power system comprising one wind farm. WT1-WT5 represent the five wind turbines in the onshore wind farm, and G1-G4 represent the four generators in the system. Information exchange between the wind turbines within the farm is as follows: Figure 5 As shown.

[0058] Under an 800MW load surge disturbance, frequency support control was implemented on the wind turbines in the wind farm using the frequency support control method proposed in this invention, the existing frequency support control method (i.e., distributed control method), and a strategy where the wind turbines do not participate in frequency support. The system frequency versus time curves under different frequency support control strategies are shown below. Figure 6 As shown, without the control method proposed in this invention, the minimum frequency point is lower; however, with the wind turbine frequency support control method provided in this invention, the minimum frequency point is improved.

[0059] The present invention also provides a wind turbine frequency support device, comprising:

[0060] The first control module is used to receive frequency signals from the main wind turbine when a frequency fault occurs at the wind farm. f And participate in frequency support according to comprehensive inertia control; in the wind farm, one wind turbine is the main wind turbine WT1, and the rest of the wind turbines are non-main wind turbines;

[0061] The data processing module is used to utilize the real-time rotational speed of each fan. oh r,i Initial speed oh r,i0 and minimum speed limit oh r,min Calculate the WT of each wind turbine i Real-time changing consistent state quantity x i ; i Indicates the fan number;

[0062] The second control module is used to control the consistency of state variables of each adjacent wind turbine. x i The exchange allows each non-dominant wind turbine to sense the frequency changes received by the dominant wind turbine, and thus follow the frequency adjustment action of the dominant wind turbine to participate in frequency support until the preset frequency support time ends.

[0063] Specifically, at the beginning of the wind turbine frequency support t b Obtain the minimum speed limit of the fan. oh r,min and the initial speed of each wind turbine in the field. oh r,i0 and in the time period t b ~ t b +Δ t Obtain the real-time speed of each fan oh r,i and system frequency fAnd trigger the data processing module to calculate the consistency state quantity. x i .

[0064] Among them, according to Get wind turbine WT i Consistent state quantity x i And calculate the state reference power value of each fan. ,according to Calculate the overall inertia power value of the main fan, and then trigger the second control module; k opt This represents the tracking coefficient in the equation of the maximum power point tracking curve; k P,i , k I,i These are the proportional integral coefficients for the state differences between the wind turbine and its neighboring turbines. k wdr,i For wind turbine i Sag coefficient, k win,i The inertia coefficient, f d represents the system frequency deviation. f / d t This represents the rate of change of frequency.

[0065] Furthermore, the second control module is used to perform torque control on the fan, thereby controlling the instantaneous stator power of the non-dominant fan. P si and real-time rotation speed oh r,i In time period t b ~ t b +Δ t Internal satisfaction ; to increase the instantaneous stator power of the main blower P si and real-time rotation speed oh r,i In time period t b ~ t b +Δ t Internal satisfaction This allows for a reasonable allocation of frequency-supported power, thereby raising the minimum frequency of the system.

[0066] In one embodiment, the wind turbine frequency support device further includes a maximum power point tracking (MPPT) module, used to adjust the wind turbine WT before and after the start of wind turbine frequency support. i Torque control is performed to adjust the instantaneous stator power. Psi and real-time rotation speed oh r,i satisfy .

[0067] The present invention also provides a wind farm, including multiple wind turbines, each of which is equipped with the aforementioned wind turbine frequency support device.

[0068] The present invention also provides a wind turbine frequency support system, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the above method.

[0069] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described method.

[0070] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for supporting the frequency of a wind turbine, characterized in that, include: S1: When a frequency fault occurs at the wind farm, the main wind turbine receives the frequency signal. f The frequency support is controlled by the comprehensive inertia control; one wind turbine in the wind farm is the dominant wind turbine WT1, and the rest of the wind turbines are non-dominant wind turbines; S2: Utilize the real-time rotational speed of each of the aforementioned fans. ω r,i Initial speed ω r,i0 and minimum speed limit ω r,min Calculate the WT of each of the aforementioned wind turbines i Real-time changing consistent state quantity x i ; i Indicates the fan number; S3: Control the consistency of state variables of each adjacent fan. x i The exchange allows each of the non-dominant wind turbines to sense the frequency change received by the dominant wind turbine, and thus follow the frequency modulation action of the dominant wind turbine to participate in frequency support until the preset frequency support time ends. S3 includes: S31: Controlling each adjacent wind turbine to achieve a consistent state quantity x i The exchange allows each of the non-dominant wind turbines to sense the state changes of adjacent wind turbines, wherein the wind turbine adjacent to the dominant wind turbine transmits the frequency changes received by the dominant wind turbine to the other non-dominant wind turbines; S32: Each of the non-dominant wind turbines adjusts its instantaneous stator power according to the consistency variables of adjacent wind turbines. P si This allows the rotational speed to be controlled, enabling each of the non-dominant fans to follow the frequency modulation action of the dominant fan and participate in frequency support. S32 includes: using the formula Calculate the instantaneous stator power of each of the aforementioned non-dominant wind turbines. P si This allows for the control of the rotational speed of each of the non-dominant fans; wherein, k opt This represents the tracking coefficient in the maximum power point tracking curve equation; the main fan corresponds to L i For 1, each of the aforementioned non-dominant wind turbines L i =0; P x,i ( t () indicates the state reference power value. P w,i ( t ) represents the combined inertia power value.

2. The wind turbine frequency support method as described in claim 1, characterized in that, S2 includes: Using formula Calculate the uniformity state variables of each of the aforementioned wind turbines. x i .

3. The wind turbine frequency support method as described in claim 1, characterized in that, The state reference power value P x,i ( t ) is represented as: ； in, k P,i , k I,i These are the proportion and integral coefficient of the state difference between each wind turbine and its neighboring wind turbines.

4. The wind turbine frequency support method as described in claim 1, characterized in that, The combined inertia power value P w,i ( t ) is represented as: ; k wdr,i For wind turbine i The droop coefficient, k win,i For wind turbine i The coefficient of inertia, f d represents the system frequency deviation. f / d t It represents the rate of change of frequency.

5. The wind turbine frequency support method according to any one of claims 1-4, characterized in that, Also includes: Before and after the start of wind turbine frequency support, the WT values ​​of each wind turbine are... i Torque control is performed to adjust the instantaneous stator power. P si and real-time rotation speed ω r,i satisfy , k opt This represents the tracking coefficient in the maximum power point tracking curve equation.

6. A wind turbine frequency support device, characterized in that, The method for performing the wind turbine frequency support method according to any one of claims 1-5 includes: The first control module is used to receive frequency signals from the main wind turbine when a frequency fault occurs at the wind farm. f The frequency support is controlled by the comprehensive inertia control; one wind turbine in the wind farm is the dominant wind turbine WT1, and the rest of the wind turbines are non-dominant wind turbines; The data processing module is used to utilize the real-time rotational speed of each of the aforementioned wind turbines. ω r,i Initial speed ω r,i0 and minimum speed limit ω r,min Calculate the WT of each of the aforementioned wind turbines i Real-time changing consistent state quantity x i ; i Indicates the fan number; The second control module is used to control the consistency of state variables of each adjacent wind turbine. x i The exchange allows each of the non-dominant fans to sense the frequency change received by the dominant fan, and thus follow the frequency adjustment action of the dominant fan to participate in frequency support until the preset frequency support time ends.

7. A wind turbine frequency support system, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

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