Cooperative control method and device for primary frequency modulation of wind generating set under variable wind speed

Abstract

The invention discloses a primary frequency modulation cooperative control method and device for a wind generating set under variable wind speed. The method comprises the steps that a wind speed predicted value is predicted according to the running state of the wind generating set; a first interval critical value is calculated according to the reserved overspeed load shedding level, and a second interval critical value is calculated according to the rotating speed maximum value and the tip speed ratio; judging whether the wind speed is in a low wind speed range, a middle wind speed range or a high wind speed range based on the wind speed predicted value, the first interval critical value and the second interval critical value, and selecting a corresponding load shedding frequency modulation strategy; within the low-wind-speed range and the medium-wind-speed range, reference rotating speed is calculated according to the reserved overspeed load shedding level and transmitted to the rotating speed control process of the wind turbine generator; in a middle wind speed range and a high wind speed range, a pitch angle is adjusted and transmitted to a pitch angle control process, and meanwhile, maximum rotating speed control and primary frequency modulation response are considered; and coefficients in cooperative control are set according to different wind speed stages.

Description

Technical Field

[0001] The present application relates to a method and device for coordinated control of primary frequency regulation of a wind generator set under variable wind speed, belonging to the field of primary frequency regulation of a wind generator set. Background Art

[0002] With the increasing proportion of wind power generation in the energy structure and the continuous progress and improvement of control technology, higher requirements are placed on the primary frequency regulation capability of wind power generation systems. New energy power stations must have a primary frequency regulation function to ensure that they can provide necessary inertial support when the access rate of new energy power stations is high. Compared with inertia response, although the response time of primary frequency regulation is relatively slow, it can provide more lasting active support, thereby ensuring the stable operation of the power system. In traditional power systems, the primary frequency regulation of synchronous generators is mainly achieved by speed regulation. When the frequency of the power system is disturbed, the speed of the synchronous motor will also change accordingly. In this case, the entire speed regulation system can quickly complete the primary frequency regulation within tens of seconds to cope with the frequency change. However, the primary frequency regulation of wind power generation systems is very different from traditional power systems. Wind power generation systems mainly use control strategies to obtain torque reference values ​​according to frequency changes, and adjust active power through converters. At present, wind turbines mainly use rotor kinetic energy release, overspeed standby, and pitch angle adjustment to support frequency disturbances. However, these control strategies have some problems, such as less available reserve active power, lower cost-effectiveness, and less than ideal results, etc. These problems limit the full use of the primary frequency regulation capability of wind power generation systems, thus affecting the stability and reliability of the entire power system.

[0003] Therefore, it is necessary to propose a coordinated control method of primary frequency regulation of wind turbines under variable wind speed based on variable coefficient to enhance the response speed and stability of wind turbines. Summary of the invention

[0004] Purpose: In view of at least one of the above technical problems, the present application provides a method and device for coordinated control of primary frequency regulation of wind turbines under variable wind speed, which can effectively suppress rapid fluctuations in system frequency, reduce the frequency fluctuation rate of the system, and improve the frequency response performance of the system.

[0005] The technical solution adopted in this application is:

[0006] In a first aspect, the present application provides a method for coordinated control of primary frequency regulation of a wind turbine generator set under variable wind speed, comprising:

[0007] S1: Obtain the wind speed prediction value V according to the operating status prediction of the wind turbine generator set;

[0008] S2: Calculate the first interval critical value V according to the reserved overspeed load reduction level ω1 , calculate the critical value V of the second interval according to the maximum speed and tip speed ratio ω2 Based on the wind speed prediction value V, the first interval critical value V ω1 and the second interval critical value V ω2 , determine whether the wind speed is in the low wind speed range, medium wind speed range or high wind speed range, and select the corresponding load reduction and frequency regulation strategy;

[0009] S3: In the low wind speed range and the medium wind speed range, the reference speed is calculated according to the reserved overspeed load reduction level and transmitted to the wind turbine speed control process;

[0010] In the medium and high wind speed ranges, the pitch angle is adjusted and transmitted to the pitch angle control process, while taking into account the maximum speed control and the primary frequency modulation response;

[0011] S4: Adjust the coefficients in the coordinated control according to different wind speed stages.

[0012] In a second aspect, the present application provides a primary frequency regulation coordinated control device for a wind turbine generator set under variable wind speed, including a processor and a storage medium;

[0013] The storage medium is used to store instructions;

[0014] The processor is configured to operate according to the instructions to execute the method according to the first aspect.

[0015] In a third aspect, the present application 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 method described in the first aspect.

[0016] In a fourth aspect, the present application provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method described in the first aspect when executing the computer program.

[0017] In a fifth aspect, the present application provides a computer program product, comprising a computer program, which implements the steps of the method described in the first aspect when executed by a processor.

[0018] Beneficial effects: The method and device for coordinated control of primary frequency regulation of wind turbine generator sets under variable wind speed provided by the present application can select appropriate control methods according to different wind speeds, and integrate the overspeed load reduction and pitch angle control link parameters in combination with the wind turbine load reduction rate to adapt to frequency response under full wind speed. It can effectively suppress the rapid fluctuation of system frequency, reduce the frequency fluctuation rate of the system, and improve the frequency response performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of a coordinated control method for primary frequency regulation of a wind turbine generator set under variable wind speed according to an embodiment of the present application;

[0020] Figure 2 A schematic diagram of the flow of optimizing the Elman neural network algorithm using the whale algorithm in one embodiment of the present application;

[0021] Figure 3 It is a schematic diagram of the overspeed and pitch coordination control process according to one embodiment of the present application. DETAILED DESCRIPTION

[0022] The present application is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and cannot be used to limit the protection scope of the present application.

[0023] In the description of this application, "several" means more than one, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0024] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0025] Embodiment 1: This embodiment provides a method for coordinated control of primary frequency regulation of a wind turbine generator set under variable wind speed. Figure 1 As shown, including:

[0026] S1: Obtain the wind speed prediction value V according to the operating status prediction of the wind turbine generator set;

[0027] S2: Calculate the first interval critical value V according to the reserved overspeed load reduction level ω1 , calculate the critical value V of the second interval according to the maximum speed and tip speed ratio ω2 Based on the wind speed prediction value V, the first interval critical value V ω1 and the second interval critical value V ω2 , determine whether the wind speed is in the low wind speed range, medium wind speed range or high wind speed range, and select the corresponding load reduction and frequency regulation strategy;

[0028] S3: In the low wind speed range and the medium wind speed range, the reference speed is calculated according to the reserved overspeed load reduction level and transmitted to the wind turbine speed control process;

[0029] In the medium and high wind speed ranges, the pitch angle is adjusted and transmitted to the pitch angle control process, while taking into account the maximum speed control and the primary frequency modulation response;

[0030] S4: Adjust the coefficients in the coordinated control according to different wind speed stages.

[0031] Table 1

[0032] Speed ​​range Pitch angle range Control scheme Low wind speed <![CDATA[ω c ,oh max ]]> <![CDATA[β′ ref =0]]> Overspeed load shedding Medium wind speed <![CDATA[ω m ,oh max ]]> <![CDATA[(β0,β m )]]> Overspeed Pitch Coordinated Control High wind speed <![CDATA[ω ref =ω max ]]> <![CDATA[(0,β ref )]]> Pitch control

[0033] As shown in Table 1, the control strategies adopted under different wind speed conditions are given, and the corresponding selection of parameters such as reference speed and pitch angle are given, which provides a theoretical basis for further coordinated control.

[0034] In some embodiments, step S2 includes:

[0035] S2.1: In the wind speed stage determination problem, calculate the critical value of the second interval, the formula is:

[0036]

[0037] Where V ω2 is the critical value of the second interval, ω max is the maximum speed, λ N is the tip speed ratio;

[0038] S2.2: Assume that the maximum wind power of the wind turbine is P0, and the corresponding speed is ω0. After the preset reserved overspeed reduction level d%, the rotor speed just reaches the maximum speed ω max , calculate the corresponding fan output power P1 at this time, P1 = (1-d%) P0, calculate the corresponding first interval critical value V ω1 ;

[0039] S2.3: When the wind speed V in <V<V ω1 When V in 、V out is the wind speed at the inlet and outlet of the wind turbine generator set. If the overspeed load reduction needs to have a reserved overspeed load reduction level of d%, when the wind turbine generator set operates in the maximum power area, the output power is proportional to the cube of the wind speed. The overspeed load reduction limit level and the wind speed are fitted three times to obtain the relationship between the overspeed load reduction limit level and the wind speed. The formula is:

[0040] dmax%=-0.002879V3 +0.02817V 2 -0.1642V+1.312

[0041] Among them, dmax% is the overspeed load reduction limit level, and V is the actual wind speed;

[0042] S2.4: When the wind speed forecast value V>V ω1 , that is, when the required load reduction level exceeds the preset reserved overspeed load reduction level d%, the load reduction measures are enhanced by increasing the pitch angle.

[0043] In some embodiments, step S3 includes:

[0044] (1) Low wind speed range

[0045] The power output of the frequency domain response characteristic link is as follows:

[0046]

[0047] Among them, P C is the power after load reduction, P B is the power under normal operation, ΔP δ is the power reduced by frequency regulation; f is the current grid frequency; Δf is the frequency deviation;

[0048] At this time, the overspeed load reduction level becomes:

[0049] Among them, d% is the reserved overspeed load reduction level, d δ % is the load reduction power factor required for frequency regulation, ΔP δ is the power reduced by frequency modulation, d ref % is the overspeed load reduction level after the first frequency regulation, P mppt is the maximum power;

[0050] Since the control path is P mppt -ω r part of r is the speed, and the speed corresponding to the load reduction level ω is calculated according to the following formula c , the reference speed ω ref ∈(ω c ,ω max ),ω max is the maximum speed;

[0051]

[0052] Where P A is the original power output, ρ is the air density, R is the radius of the wind wheel, and V is the actual wind speed; C p is the wind energy utilization coefficient, v0 is the linear speed of the wind wheel;

[0053] (2) Medium wind speed range

[0054] The reserved overspeed load reduction level of the wind turbine is d%. The required load reduction level cannot be met by overspeed load reduction alone. At this time, it is necessary to cooperate with the pitch angle load reduction to achieve the required load reduction level by increasing the pitch angle reserve; reduce the pitch angle to β m , the speed is from ω max Reduce to ω m ; To obtain the same load reduction and frequency modulation effect at different pitch angles and speeds, it is necessary to ensure that the operating point satisfies the following formula:

[0055]

[0056] Among them, P m is the adjusted power, ω m is the rotation speed after integration, β m is the adjusted pitch angle;

[0057] Arriving at point D meets the requirements, according to the corresponding speed ω max , substituted into the formula of the fitting curve, we can get the reference pitch angle of point D. Since the control path DA can be approximated as a straight line, if the power increment of the system frequency modulation is ΔP δ2 When the primary frequency modulation active power curve is GE, it intersects with the DA path at point G. Therefore, the pitch angle can be controlled to be reduced to β m , the speed is from ω max Reduce to ω m Therefore, on the GE line, there are many combinations of pitch angle load reduction and overspeed load reduction that can achieve the same load reduction and frequency regulation level. Figure 3 As shown, the corresponding pitch angle and rotation speed are calculated based on the mechanical power.

[0058] (3) High wind speed range

[0059] At this time, the speed has reached the maximum speed ω ref =ω max , combined with the calculation formula of wind energy utilization coefficient, the reference value β of the reserved pitch angle under different wind speeds and load reduction rates at high wind speeds is obtained. ref ; At high wind speeds, the power during this period will be greater, and at the same reduction rate, the reserved pitch angle will decrease with the increase of wind speed; when the wind speed remains unchanged, the load reduction rate can be increased as the pitch angle reserved for load reduction increases.

[0060] In some embodiments, in S4, the collaborative control is expressed by the formula:

[0061]

[0062] in, is the optimal speed, Δf is the frequency deviation, K ω K is the overspeed load reduction standby parameter. β is the parameter of the pitch angle backup link, β ref is the reserved pitch angle reference value, ω1 is the rotation speed after low wind speed adjustment, β1 is the pitch angle after low wind speed adjustment, ω2 is the rotation speed after medium wind speed adjustment, β2 is the pitch angle after medium wind speed adjustment, β0 is the pitch angle before medium wind speed adjustment, ω3 is the rotation speed after high wind speed adjustment, β3 is the pitch angle after high wind speed adjustment.

[0063] On this basis, the reserved pitch angle reference value β ref The parameter K of the pitch angle backup link under different wind speeds is calculated by using the frequency deviation Δf. β Perform adjustment;

[0064] According to the wind speed range in which the doubly-fed wind turbine generator set operates, the overspeed load reduction standby parameter K is set. ω size;

[0065]

[0066] in, is the optimal speed, ω mppt is the speed of the wind turbine at maximum power.

[0067] In some embodiments, in step S1, the Elman neural network optimized by the whale algorithm is used to predict the wind speed according to the operating status of the wind turbine generator set.

[0068] like Figure 2 As shown in the figure, the Elman neural network optimized by the whale algorithm includes:

[0069] S1.1: Initialize the population: a certain number of whale individuals need to be randomly generated, each of which represents a solution;

[0070] S1.2 Calculate fitness: Substitute each individual into the recursive neural network Elman and calculate its prediction error as fitness;

[0071] S1.3: Update position: Update the position of each individual in the population according to the currently obtained optimal solution and worst solution;

[0072] S1.4: Update fitness: Substitute the updated individuals into the recurrent neural network Elman and recalculate the fitness;

[0073] S1.5: Determine the termination condition: If the preset termination condition is met, output the optimal solution; otherwise return to S1.3.

[0074] Embodiment 2: Based on Embodiment 1, this embodiment provides a primary frequency regulation coordinated control device for a wind turbine generator set under variable wind speed, including a processor and a storage medium;

[0075] The storage medium is used to store instructions;

[0076] The processor is used to operate according to the instructions to execute the steps of the method according to embodiment 1.

[0077] Embodiment 3: Based on Embodiment 1, this embodiment provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in Embodiment 1 are implemented.

[0078] Embodiment 4: Based on Embodiment 1, this embodiment provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method described in Embodiment 1 when executing the computer program.

[0079] Embodiment 5: Based on Embodiment 1, this embodiment provides a computer program product, including a computer program, which implements the steps of the method described in Embodiment 1 when executed by a processor.

[0080] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0081] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0082] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0083] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0084] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for coordinated control of primary frequency regulation of wind turbine generator sets under variable wind speed, characterized in that: include: S1: Obtain the wind speed prediction value V according to the operating status prediction of the wind turbine generator set; S2: Calculate the first interval critical value V according to the reserved overspeed load reduction level ω1 , calculate the critical value V of the second interval according to the maximum speed and tip speed ratio ω2 Based on the wind speed prediction value V, the first interval critical value V ω1 and the second interval critical value V ω2 , determine whether the wind speed is in the low wind speed range, medium wind speed range or high wind speed range, and select the corresponding load reduction and frequency regulation strategy; S3: In the low wind speed range and the medium wind speed range, the reference speed is calculated according to the reserved overspeed load reduction level and transmitted to the wind turbine speed control process; In the medium and high wind speed ranges, the pitch angle is adjusted and transmitted to the pitch angle control process, while taking into account the maximum speed control and the primary frequency modulation response; S4: Adjust the coefficients in the coordinated control according to different wind speed stages.

2. The method according to claim 1, characterized in that Step S2 includes: S2.1: In the wind speed stage determination problem, calculate the critical value of the second interval, the formula is: Among them, V ω2 is the critical value of the second interval, ω max is the maximum speed, λ N is the tip speed ratio; S2.2: Assume that the maximum wind power of the wind turbine is P0, and the corresponding speed is ω0. After the preset reserved overspeed reduction level d%, the rotor speed just reaches the maximum speed ω max , calculate the corresponding fan output power P1 at this time, P1 = (1-d%) P0, calculate the corresponding first interval critical value V ω1 ; S2.3: When the wind speed V in <V<V ω1 When V in 、V out is the wind speed at the inlet and outlet of the wind turbine generator set. If the overspeed load reduction needs to have a reserved overspeed load reduction level of d%, when the wind turbine generator set operates in the maximum power area, the output power is proportional to the cube of the wind speed. The overspeed load reduction limit level and the wind speed are fitted three times to obtain the relationship between the overspeed load reduction limit level and the wind speed. The formula is: dmax%=-0.002879V 3 +0.02817V 2 -0.1642V+1.312; Among them, dmax% is the overspeed load reduction limit level, and V is the actual wind speed; S2.4: When the wind speed forecast value V>V ω1 , that is, when the required load reduction level exceeds the preset reserved overspeed load reduction level d%, the load reduction measures are enhanced by increasing the pitch angle.

3. The method according to claim 1, characterized in that Step S3 includes: (1) Low wind speed range The power output of the frequency domain response characteristic link is as follows: Among them, P C is the power after load reduction, P B is the power under normal operation, ΔP δ is the power reduced by frequency regulation; f is the current grid frequency; Δf is the frequency deviation; At this time, the overspeed load reduction level becomes: Among them, d% is the reserved overspeed load reduction level, d δ % is the load reduction power factor required for frequency regulation, ΔP δ is the power reduced by frequency modulation, d ref % is the overspeed load reduction level after the first frequency regulation, P mppt is the maximum power; The speed ω corresponding to the load reduction level is calculated according to the following formula c , the reference speed ω ref ∈(ω c ,ω max ),ω max is the maximum speed; Where P A is the original power output, ρ is the air density, R is the radius of the wind wheel, and V is the actual wind speed; C p is the wind energy utilization coefficient, v0 is the linear speed of the wind wheel; (2) Medium wind speed range The reserved overspeed load reduction level of the wind turbine is d%. The overspeed load reduction alone cannot meet the required load reduction level. At this time, it is necessary to cooperate with the pitch angle load reduction to achieve the required load reduction level by increasing the pitch angle reserve; reduce the pitch angle to β m , the speed is from ω max Reduce to ω m ; To obtain the same load reduction and frequency modulation effect at different pitch angles and speeds, it is necessary to ensure that the operating point satisfies the following formula: Among them, P m is the adjusted power, ω m is the rotation speed after integration, β m is the adjusted pitch angle; (3) High wind speed range At this time, the speed has reached the maximum speed ω ref =ω max , combined with the calculation formula of wind energy utilization coefficient, the reference value β of the reserved pitch angle under different wind speeds and load reduction rates at high wind speeds is obtained. ref ; When the wind speed remains unchanged, the load shedding rate can be increased as the pitch angle reserved for load shedding increases.

4. The method according to claim 1, characterized in that In S4, the collaborative control is expressed by the formula: in, is the optimal speed, Δf is the frequency deviation, K ω K is the overspeed load reduction standby parameter. β is the parameter of the pitch angle backup link, β ref is the reserved pitch angle reference value, ω1 is the speed after low wind speed adjustment, β1 is the pitch angle after low wind speed adjustment, ω2 is the speed after medium wind speed adjustment, β 2 is the pitch angle after adjustment for medium wind speed, β0 is the pitch angle before adjustment for medium wind speed, ω3 is the rotation speed after adjustment for high wind speed, and β3 is the pitch angle after adjustment for high wind speed.

5. The method according to claim 4, characterized in that By the reserved pitch angle reference value β ref The parameter K of the pitch angle backup link under different wind speeds is calculated by using the frequency deviation Δf. β Perform adjustment; According to the wind speed range in which the doubly-fed wind turbine generator set operates, the overspeed load reduction standby parameter K is set. ω size; in, is the optimal speed, ω mppt is the speed of the wind turbine at maximum power.

6. The method according to claim 1, characterized in that In step S1, the Elman neural network optimized by the whale algorithm is used to predict the wind speed according to the operating status of the wind turbine generator set.

7. The method according to claim 6, characterized in that The Elman neural network optimized by the whale algorithm includes: S1.1: Initialize the population: a certain number of whale individuals need to be randomly generated, each of which represents a solution; S1.2 Calculate fitness: Substitute each individual into the recursive neural network Elman and calculate its prediction error as fitness; S1.3: Update position: Update the position of each individual in the population according to the currently obtained optimal solution and worst solution; S1.4: Update fitness: Substitute the updated individuals into the recurrent neural network Elman and recalculate the fitness; S1.5: Determine the termination condition: If the preset termination condition is met, output the optimal solution; otherwise return to S1.

3.

8. A primary frequency modulation coordinated control device for a wind turbine generator set under variable wind speed, characterized in that: including processor and storage medium; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

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