Wind farm reserve frequency modulation capacity control method, control device, system and equipment

Abstract

The application provides a wind farm backup frequency modulation capacity control method, a control device, a system and equipment. First, a dispatching instruction issued by a wind farm control center is received and the wind speed of each wind turbine is obtained. Then, the load shedding mode of each wind turbine is determined according to the wind speed of each wind turbine. The load shedding mode of the wind turbine with the wind speed less than a first preset threshold is an overspeed load shedding mode, and the load shedding mode of the wind turbine with the wind speed greater than a second preset threshold is a low-speed load shedding mode. The second preset threshold is greater than or equal to the first preset threshold. Meanwhile, the load shedding power of each wind turbine is determined according to the wind speed of each wind turbine and the dispatching load shedding power indicated by the dispatching instruction. Finally, the load shedding of each wind turbine is realized according to the load shedding mode and the load shedding power of each wind turbine. By matching the low-speed load shedding mode for the high-speed wind turbine, compared with the variable pitch control of the prior art, the response speed can be improved, the wind turbine can be quickly adjusted to the backup capacity, and therefore the practicability of the control strategy is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power grid frequency control, and particularly relates to a wind farm reserve frequency modulation capacity control method, a control device, a system and equipment. BACKGROUND

[0002] With the increase of wind power grid-connected capacity, the grid-connected capacity of traditional synchronous units is gradually reduced, and the safety problem of system frequency is increasingly prominent. Doubly fed induction generators (DFIG) are widely used mainstream models, which realize grid connection through a converter, resulting in decoupling of unit speed and system frequency, and being unable to actively respond to system frequency changes. With the increase of wind power grid-connected capacity, a part of reserve capacity should be left for wind turbine units, and the wind turbine units can undertake part of the frequency modulation task.

[0003] The current wind farm reserve capacity allocation strategy is as follows: one is to use the overspeed load shedding of low wind speed units and the variable pitch control load shedding of medium and high wind speed units. The other is to consider that the active output of DFIG is approximately proportional to the cube of wind speed, and to use the wind speed cube weighted load shedding capacity allocation strategy. However, since the variable pitch control is executed by mechanical components, its response speed is slow and mechanical wear is easy to occur, and the wind speed cube weighted load shedding capacity allocation method has a complex control process and needs to occupy a large amount of computing resources. Therefore, the reserve capacity control strategy in the prior art has low practicability. SUMMARY

[0004] Therefore, the application provides a wind farm reserve frequency modulation capacity control method, a control device, a system and equipment, aiming to solve the problem of low practicability of the reserve capacity control strategy in the prior art.

[0005] A first aspect of the embodiment of the application provides a wind farm reserve frequency modulation capacity control method, comprising the following steps.

[0006] receiving a dispatch instruction issued by a wind farm control center and obtaining the wind speed of each wind turbine;

[0007] determining the load shedding mode of each wind turbine according to the wind speed of each wind turbine; wherein the load shedding mode of the wind turbine with a wind speed less than a first preset threshold is an overspeed load shedding mode, and the load shedding mode of the wind turbine with a wind speed greater than a second preset threshold is a low-speed load shedding mode; wherein the second preset threshold is greater than or equal to the first preset threshold;

[0008] determining the load shedding power of each wind turbine according to the wind speed of each wind turbine and the dispatch load shedding power indicated by the dispatch instruction;

[0009] shedding the load of each wind turbine according to the load shedding mode of each wind turbine and the load shedding power of each wind turbine.

[0010] The second aspect of the embodiment of the present application provides a wind farm reserve frequency modulation capacity control device, comprising:

[0011] An acquisition module is configured to receive a dispatch instruction issued by a wind farm control center and acquire wind speeds of wind turbines.

[0012] A determination module is configured to determine load shedding modes of the wind turbines according to the wind speeds of the wind turbines; wherein the load shedding mode of a wind turbine with a wind speed less than a first preset threshold is an overspeed load shedding mode, and the load shedding mode of a wind turbine with a wind speed greater than a second preset threshold is a low-speed load shedding mode; wherein the second preset threshold is greater than or equal to the first preset threshold.

[0013] A calculation module is configured to determine load shedding powers of the wind turbines according to the wind speeds of the wind turbines and a dispatch load shedding power indicated by the dispatch instruction.

[0014] A load shedding module is configured to perform load shedding on the wind turbines according to the load shedding modes of the wind turbines and the load shedding powers of the wind turbines.

[0015] The third aspect of the embodiment of the present application provides a control device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the wind farm reserve frequency modulation capacity control method of the first aspect when executing the computer program.

[0016] The fourth aspect of the embodiment of the present application provides a doubly-fed wind power generation system, comprising a wind turbine, a rotating shaft, a generator, and the control device of the third aspect; the control device is connected with the wind turbine, the rotating shaft, and the generator respectively.

[0017] The fifth aspect of the embodiment of the present application provides a computer readable storage medium, the computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of the wind farm reserve frequency modulation capacity control method of the first aspect.

[0018] The wind farm reserve frequency modulation capacity control method, control device, system and equipment provided by the embodiment of the present application first receive the dispatching instruction issued by the wind farm control center and obtain the wind speed of each wind turbine; then determine the load shedding mode of each wind turbine according to the wind speed of each wind turbine; wherein the load shedding mode of the wind turbine with a wind speed less than a first preset threshold is an overspeed load shedding mode, and the load shedding mode of the wind turbine with a wind speed greater than a second preset threshold is a low-speed load shedding mode; wherein the second preset threshold is greater than or equal to the first preset threshold; at the same time, the load shedding power of each wind turbine is determined according to the wind speed of each wind turbine and the dispatching load shedding power indicated by the dispatching instruction; finally, the load shedding of each wind turbine is realized according to the load shedding mode of each wind turbine and the load shedding power of each wind turbine. By matching the low-speed load shedding mode for the high-speed wind turbine set, compared with the variable pitch control of the prior art, the control does not need mechanical components, the response speed can be improved, the wind turbine set can be quickly adjusted to reserve capacity, and therefore the practicability of the control strategy is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 is an application scenario diagram of the wind farm reserve frequency modulation capacity control method provided by the embodiment of the present application;

[0021] Figure 2 is a flowchart of the implementation of the wind farm reserve frequency modulation capacity control method provided by the embodiment of the present application;

[0022] Figure 3 is a wind turbine load shedding control logic diagram provided by the embodiment of the present application;

[0023] Figure 4 is a calculation diagram of the load shedding power of each wind turbine in the embodiment of the present application;

[0024] Figure 5 is a power grid model of 4 machines and 2 areas provided by the embodiment of the present application;

[0025] Figure 6 is a wind turbine available frequency modulation capacity diagram provided by the embodiment of the present application;

[0026] Figure 7 is an available frequency modulation capacity-speed curve diagram provided by the embodiment of the present application;

[0027] Figure 8 is a speed bidirectional load shedding control curve diagram provided by the embodiment of the present application;

[0028] Figure 9 The maximum load reduction power diagram of DFIG under different wind speeds is provided as an example of an implementation of the present invention;

[0029] Figure 10 This is a schematic diagram of the wind farm load reduction process under different strategies when the wind speed is low, provided by an embodiment of the present invention.

[0030] Figure 11 This is a graph showing the system frequency variation under low wind speeds, provided in an embodiment of the present invention.

[0031] Figure 12 This is a wind farm variation curve at low wind speed provided in an embodiment of the present invention;

[0032] Figure 13 This is a schematic diagram of the wind farm load reduction process under different strategies when the wind speed is high, provided by an embodiment of the present invention.

[0033] Figure 14 This is a graph showing the frequency variation of the system under high wind speeds, provided in an embodiment of the present invention.

[0034] Figure 15 This is a wind farm variation curve under high wind speed provided in an embodiment of the present invention;

[0035] Figure 16 This is a schematic diagram of the wind farm backup frequency regulation capacity control device provided in an embodiment of the present invention;

[0036] Figure 17 This is a schematic diagram of the control device provided in an embodiment of the present invention. Detailed Implementation

[0037] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0038] Figure 1 This is an application scenario diagram of the wind farm backup frequency regulation capacity control method provided in the embodiments of the present invention. For example... Figure 1 As shown, the wind farm backup frequency regulation capacity control method provided in this embodiment of the invention can be applied to, but is not limited to, this application scenario. In some embodiments, the wind farm backup frequency regulation capacity control method can be used in a doubly-fed wind power generation system, which includes: a wind turbine 11, a shaft 12, a generator 13, and a control device 14; the control device 14 is connected to the wind turbine 11, the shaft 12, and the generator 13 respectively.

[0039] The wind turbine 11, the rotating shaft 12 and the generator 13 form a wind turbine (hereinafter referred to as a fan). The wind turbine 11 drives the generator 13 to work through the rotating shaft 12, so as to supply power to the power grid. The control device 14 obtains the power generation power of each generator 13 connected thereto in real time, and combines the rotating speed of the rotating shaft 12 connected with each generator 13, so as to make the generator work in the MPPT (Maximum PowerPoint Tracking) mode. When the control device 14 receives the dispatching instruction issued by the wind farm control center, the selection switch is switched from the MPPT mode to the load shedding mode, so as to perform load shedding on each generator connected thereto, so as to make the wind farm retain sufficient standby frequency modulation capacity.

[0040] The output model of the wind turbine 11 is:

[0041]

[0042] Among them, P w P is the power of the wind turbine 11, p is the atmospheric density, R is the radius of the wind turbine blade, v is the input wind speed, C p (λ, β) is the wind energy utilization coefficient of the wind turbine, l is the tip speed ratio, β , l is the pitch angle of the fan, w is the mechanical rotating speed of the fan. β w The transfer function of the rotating shaft 12 is:

[0043]

[0044]

[0045] Among them, T m is the mechanical torque of the fan, T e is the electromagnetic torque of the generator, D is the damping coefficient, w r is the rotating speed of the rotating shaft, H w is the inertia time constant, t is time.

[0046] Figure 2 The wind farm standby frequency modulation capacity control method provided by the embodiment of the application is shown in the flowchart. As shown in Figure 2 some embodiments, the wind farm standby frequency modulation capacity control method is applied to​​Figure 1 The method comprises the following steps of:

[0047] S210, receiving the dispatching instruction issued by the wind farm control center and obtaining the wind speed of each wind turbine.

[0048] Figure 3 is the wind turbine load shedding control logic provided by the embodiment of the present application. As shown in the figure, Figure 3 In the embodiment of the present application, the wind turbine generally works in the MPPT mode, that is, the switch selects the MTTP mode end, and the expression is:

[0049]

[0050] wherein ω ref1 is the first reference speed, P is the generator output power, a , b , c is a to-be-determined coefficient, which is obtained by fitting the MPPT point power under different wind speeds.

[0051] After receiving the dispatching instruction issued by the wind farm control center, the switch is switched to the load shedding mode end, so as to realize the standby frequency modulation capacity control.

[0052] In the embodiment of the present application, the dispatching instruction contains the dispatching load shedding power. Considering the influence of the internal wake flow and the terrain of the wind farm, the wind speed in the area where the wind turbine is located is different, and the standby capacity reservation is also different. Therefore, different load shedding strategies need to be formulated for the wind turbine under different wind speeds.

[0053] S220, determining the load shedding mode of each wind turbine according to the wind speed of each wind turbine; wherein the load shedding mode of the wind turbine with a wind speed less than a first preset threshold is an overspeed load shedding mode, and the load shedding mode of the wind turbine with a wind speed greater than a second preset threshold is a low-speed load shedding mode; wherein the second preset threshold is greater than or equal to the first preset threshold.

[0054] In the embodiment of the present application, the intersection point of the different wind speed curves and the available frequency modulation capacity of the wind turbine is the MPPT point. The wind turbine works in the overspeed load shedding mode when the wind speed is greater than the MPPT point, and works in the low-speed load shedding mode when the wind speed is less than the MPPT point. At low wind speed, the overspeed load shedding can provide more frequency modulation capacity, so the overspeed load shedding is more suitable at low wind speed; at high wind speed, the low-speed load shedding can provide more frequency modulation capacity, so the low-speed load shedding is more suitable at high wind speed.

[0055] Since the wind turbine is connected with the rotating shaft, the wind speed can be reflected by the rotating speed of the rotating shaft. Figure 3 The rotating speed value of the rotating shaft shown in the figure is only an example of the present application and is not limited.

[0056] S230 determines the load reduction power of each wind turbine based on the wind speed of each turbine and the load reduction power indicated by the dispatching command.

[0057] In this embodiment of the invention, when wind speed is low, low-wind-speed turbines can generally provide sufficient frequency regulation capacity, therefore low-wind-speed turbines are preferentially unloaded. However, when wind speed is high, low-wind-speed turbines are preferentially unloaded, but some high-wind-speed turbines need to be unloaded at low speed to provide sufficient backup frequency regulation capacity.

[0058] S240 reduces the load on each wind turbine according to its load reduction mode and load reduction power.

[0059] like Figure 3 As shown in this embodiment of the invention, after selecting the low-speed load reduction mode / overspeed load reduction mode, the calculated load reduction power Δ is used... P dzi Determine the second reference rotational speed ω ref1 At this time, the selector switch is in the unload position.

[0060] Furthermore, the order of S220 and S230 described above can be interchanged without affecting the implementation of the present invention.

[0061] In this embodiment of the invention, the system first receives a dispatch command from the wind farm control center and obtains the wind speed of each wind turbine. Then, based on the wind speed of each turbine, the load reduction mode for each turbine is determined. Specifically, the load reduction mode for turbines with wind speeds less than a first preset threshold is an overspeed load reduction mode, and the load reduction mode for turbines with wind speeds greater than a second preset threshold is a low-speed load reduction mode. The second preset threshold is greater than or equal to the first preset threshold. Simultaneously, based on the wind speed of each turbine and the dispatch load reduction power indicated by the dispatch command, the load reduction power of each turbine is determined. Finally, based on the load reduction mode and the load reduction power of each turbine, the load reduction of each turbine is achieved. By matching a low-speed load reduction mode to high-wind-speed turbines, compared to the existing variable pitch control technology, no mechanical components are required for control, which improves the response speed and allows the wind turbine to quickly adjust its reserve capacity, thereby improving the practicality of the control strategy.

[0062] In some embodiments, S240 may include: determining the speed adjustment amount of each wind turbine based on the load reduction power of each wind turbine; and calculating the power reference amount input to each wind turbine based on the current speed of each wind turbine and the speed adjustment amount of each wind turbine.

[0063] like Figure 3 As shown in this embodiment of the invention, by inputting the current rotational speed and speed adjustment amount of the fan shaft into the PI controller, the electromagnetic torque reference value of the fan can be obtained. T refThen, the power reference quantity is determined according to the current rotating speed of the fan shaft and the electromagnetic torque reference value P ref , thereby realizing the control of the generator.

[0064] In some embodiments, after S220, the method further comprises: determining the rotating speed safety constraint interval corresponding to each fan according to the load shedding mode of each fan; wherein the rotating speed safety constraint interval of the low-speed load shedding mode is smaller than the rotating speed safety constraint interval of the overspeed load shedding mode.

[0065] Generally, the rotating speed safety operation interval of the doubly-fed wind turbine generator is 0.7p.u.-1.2p.u., thus the rotating speed of the fan shaft needs to be subjected to primary safety constraint, for example, , but the low-speed load shedding is prone to instability. Thus, the rotating speed thereof needs to be subjected to secondary safety constraint, for example, .

[0066] Therefore, in the embodiments of the present application, the rotating speed safety constraint interval of the overspeed load shedding mode is the interval corresponding to the primary safety constraint, and the rotating speed safety constraint interval of the low-speed load shedding mode is the interval corresponding to the secondary safety constraint. The interval values set above are only an example of the present application, and are not intended to be limiting. The secondary safety constraint can be [0.8, 1.1] for example.

[0067] In some embodiments, S230 can comprise: selecting the load shedding fan according to the scheduled load shedding power indicated by the scheduling instruction, the wind speed of each fan and the preset selection condition, and determining the load shedding power of the load shedding fan.

[0068] In some embodiments, the second preset threshold is greater than the first preset threshold. Correspondingly, S220 can comprise: setting the load shedding mode of the fan with the wind speed not less than the first preset threshold and not greater than the second preset threshold as the overspeed load shedding mode or the low-speed load shedding mode.

[0069] In the embodiments of the present application, the first preset threshold can be set as a , and the second preset threshold can be set as b . Correspondingly, when v , b , the overspeed load shedding is performed, when v > a , the low-speed load shedding is performed, and when v ∈[ b , a ], both the overspeed load shedding and the low-speed load shedding are optional modes, and can be determined according to the preset selection condition.

[0070] In some embodiments, the preset selection condition is to select according to the wind speed. Correspondingly, the wind turbines to be unloaded are selected according to the dispatching instruction, the wind speed of each wind turbine and the preset selection condition, and the unloading power of the wind turbines to be unloaded is determined, including: starting from the wind turbine with the smallest wind speed, until the sum of the maximum unloading power of the selected wind turbines exceeds the dispatching unloading power, the selected wind turbines are taken as the wind turbines to be unloaded.

[0071] In the embodiments of the present application, the wind turbines can be sorted and grouped according to the wind speed from low to high, the wind turbines with low wind speed are preferentially unloaded, and then the wind turbines with higher wind speed are unloaded in turn until the unloading standby capacity requirement is met or all the wind turbines to be unloaded are unloaded to the maximum.

[0072] Correspondingly, when the wind turbines to be unloaded are selected according to the wind speed, when the wind turbines with the wind speed of v∈[b, a] are selected, the available frequency modulation capacity provided by the overspeed unloading and the low-speed unloading is compared, and the mode with higher available frequency modulation capacity is selected as the working mode of the wind turbine. v ∈[ b , a ] of the wind turbines, the maximum unloading power provided by the overspeed unloading and the low-speed unloading is not much different. Considering that when the system occurs a sudden load disturbance in the overspeed unloading mode, the wind turbine speed decreases, on the one hand, more wind power is captured, and on the other hand, part of kinetic energy is released during the wind turbine speed reduction process, which is more conducive to relieving the system power shortage and improving the system frequency characteristics. Therefore, the overspeed unloading is preferentially adopted.

[0073] In some embodiments, the preset selection condition is to ensure the minimum number of wind turbine controls. Correspondingly, the wind turbines to be unloaded are selected according to the dispatching instruction, the wind speed of each wind turbine and the preset selection condition, and the unloading power of the wind turbines to be unloaded is determined, including: determining all wind turbine combination schemes exceeding the dispatching unloading power; and marking the wind turbines in the wind turbine combination scheme with the minimum number of wind turbine controls as the wind turbines to be unloaded in the wind turbine combination scheme exceeding the dispatching unloading power.

[0074] In the embodiments of the present application, the wind turbines can be sorted and grouped according to the wind speed from low to high, the wind turbines with low wind speed are preferentially unloaded, and then the wind turbines with higher wind speed are unloaded in turn until the unloading standby capacity requirement is met or all the wind turbines to be unloaded are unloaded to the maximum.

[0075] Correspondingly, when the wind turbines to be unloaded are selected according to the wind speed, when the wind turbines with the wind speed of v∈[b, a] are selected, the available frequency modulation capacity provided by the overspeed unloading and the low-speed unloading is compared, and the mode with higher available frequency modulation capacity is selected as the working mode of the wind turbine.

[0076] In addition, the above two preset selection conditions can be combined for use. For example, a number of optional schemes with smaller total wind speed values are selected according to the wind speed, and then the scheme with the minimum number of wind turbine controls is selected from the optional schemes.

[0077] Figure 4 is a schematic diagram of the calculation of the unloading power of each wind turbine in the embodiments of the present application. As shown in FIG. 1, the wind turbine with the wind speed of v∈[b, a] is selected as the wind turbine to be unloaded, and the unloading power of the wind turbine to be unloaded is calculated according to the wind speed of the wind turbine to be unloaded. Figure 4As shown, in some embodiments, S230 can include:

[0078]

[0079] wherein i is the serial number of the fan, the 1st fan to the n1th fan is a load shedding fan, ΔPdzmi is the maximum load shedding power of the ith fan, Pd is the dispatch load shedding power, and ΔPdzi is the load shedding power of each fan.

[0080] An implementation example of the wind farm reserve frequency modulation capacity control method of the present application is provided below for illustration, but not as a limitation.

[0081] Figure 5 is a 4-machine 2-zone power grid model provided by the implementation example of the present application. As shown Figure 5 , a wind farm with a capacity of 300 MW is in parallel operation at the G2 generator, including 5 groups of wind turbines with different wind speeds, a total of 150 DFIGs of 2 MW. The disturbance load on the bus 7 is 200 MW.

[0082] Correspondingly, the wind energy utilization coefficient of the wind farm is:

[0083]

[0084] wherein, l i is the tip speed ratio of the ith fan, i . .

[0085] When the fan adopts the rotational speed load shedding control strategy of the present application, i.e. , then is only a function of , and because , so is a function of the rotational speed and the wind speed, i.e.:

[0086]

[0087] Therefore, it can be concluded that:

[0088]

[0089] Taking the derivative of the rotational speed in the above formula, when the derivative is 0, the maximum wind energy utilization efficiency can be obtained:

[0090]

[0091] The maximum wind power output can be calculated from the above formula, and therefore, for the power The fan provided by the embodiment of the present application has a frequency modulation capacity of:

[0092]

[0093] Figure 6 The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. Figure 6 The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. Figure 1 The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line.

[0094] Figure 7 The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. Figure 7 The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line.

[0095] The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. Figure 8 The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. Figure 8 The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line.

[0096] The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line.

[0097] The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line.

[0098] The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. Figure 9 The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. Figure 9 The figure is a frequency modulation capacity curve of the fan provided by the embodiment of the present application. As shown in the figure, the curve is generally in a V shape and is divided by a dashed line. Close to the minimum safe speed 0.8p.u., without low-speed load shedding capability, the maximum low-speed load shedding power is 0; when the wind speed is high, due to Close to the maximum speed 1.2p.u., without overspeed load shedding capability, the maximum overspeed load shedding power is 0, and the difference between the two presents a process of first decreasing and then increasing, The upper envelope line formed by the two.

[0099] According to Figure 9 The load shedding mode of the wind turbine can be formulated, when the wind speed is in the range of 6.5m / s-8m / s, the overspeed load shedding is adopted; when the wind speed is in the range of 9m / s-10.5m / s, the low-speed load shedding mode is adopted; when the wind speed is in the range of 8m / s-9m / s, the maximum load shedding power of the two strategies is not much different, and the overspeed load shedding mode or the low-speed load shedding mode can be adopted, and the specific mode can be determined according to the preset selection condition.

[0100] In order to verify the superiority of the control strategy in the present application in guaranteeing the utilization rate of wind energy and the frequency modulation performance when the load disturbance occurs under the condition of meeting the reserved standby demand, two scenes can be set, and each scene adopts two strategies for verification and comparison.

[0101] Strategy 1: The total load shedding amount of the wind farm is allocated to units 1, 2 and 3 according to the wind speed cubed weighting.

[0102] Strategy 2: The total load shedding amount of the wind farm is allocated to the low wind speed priority load shedding according to the present application.

[0103] Scene 1: Low wind speed condition of the wind farm.

[0104] The actual active power of the wind farm is 95MW, and it is assumed that the dispatch center issues a load shedding instruction of 10MW: a total of 5 groups of units, the first 3 groups are set as load shedding units, and the last 2 groups of units are in MPPT mode, and then strategy 1 and 2 are applied to the first 3 groups of units respectively for analysis.

[0105] Figure 10 It is a wind farm load shedding process schematic diagram under different strategies when the wind speed is low provided by the embodiment of the present application. As Figure 10 shown, in the low wind speed condition, the wind farm output minimum point in the load shedding process of strategy 1 is low, and the wind farm output after the load shedding is also low. The wind farm output minimum point in the load shedding process of strategy 2 proposed in the present application is higher than that of strategy 1, and the wind farm outputs a larger power after the load shedding is completed. In order to further compare, the present application provides a data comparison table of using two load shedding strategies under low wind speed as shown in Table 1.

[0106] Table 1

[0107]

[0108] From the above table 1, the strategy 2 provided in the present application only needs to reduce 2 groups of units to meet the requirement of load reduction, and the control complexity is simplified.

[0109] Figure 11 is the system frequency variation curve diagram under low wind speed provided by the embodiment of the present application. Figure 12 is the wind farm variation curve diagram under low wind speed provided by the embodiment of the present application. Figure 11 and Figure 12 As shown in the above table 1, the strategy 2 provided in the present application only needs to reduce 2 groups of units to meet the requirement of load reduction, and the control complexity is simplified.

[0110] Therefore, under the condition of low wind speed, the present application can guarantee that the wind farm maximally utilizes wind energy under the condition of meeting the load reduction standby, and only needs to reduce part of the units to meet the requirement of load reduction, and the control complexity is simplified.

[0111] Scenario 2: high wind speed of the wind farm.

[0112] The actual active power of the wind farm is 203 MW, and it is assumed that the dispatching center issues a load reduction instruction of 20 MW: a total of 5 groups of units, and part of the high wind speed units need to be reduced at low speed, and the strategy 1 and 2 are applied for analysis.

[0113] Figure 13 is the wind farm load reduction process schematic diagram under different strategies when the wind speed is high provided by the embodiment of the present application. Figure 13 As shown in the above table 1, the strategy 2 provided in the present application only needs to reduce 2 groups of units to meet the requirement of load reduction, and the control complexity is simplified.

[0114] Table 2

[0115]

[0116] From the above table 2, the allocation strategy of the strategy 1 causes that the unit 2 cannot reach the allocation requirement even if it is fully reduced, and then the part exceeding the full reduction of the unit 2 needs to be shared by the other 4 units according to the proportion calculated in the strategy 1. In addition, the strategy 2 provided in the present application only needs to control part of the units to meet the requirement of load reduction, and the control complexity is simplified.

[0117] Figure 14 is the system frequency variation curve diagram under low wind speed provided by the embodiment of the present application. Figure 15 is the wind farm variation curve diagram under low wind speed provided by the embodiment of the present application. Figure 4 and Figure 5As shown, in the high wind speed case, the frequency steady points of strategy 1 and strategy 2 are the same when the load disturbance occurs at 30s, because the reserve capacity of strategy 1 and strategy 2 is the same.

[0118] The lowest point of the frequency of strategy 1 is lower than that of the MPPT mode, because the three groups of wind turbines in strategy 1 adopt low-speed load shedding, and at the moment when the load disturbance occurs, the rotor speeds of the three groups of wind turbines rise from the low-speed point to the MPPT point, so that a part of the electric power is absorbed from the wind farm, resulting in the decrease of the output of the wind farm.

[0119] The lowest point of the frequency of strategy 2 is higher than that of strategy 1 and the MPPT mode, because strategy 2 preferentially sheds the low-speed wind turbines, so that the rotor speeds are limited to 1.2p.u., and only two groups of high-speed wind turbines adopt low-speed load shedding, and when the disturbance occurs, the rotor speeds of the over-speed load shedding wind turbines decrease from the maximum value to the MPPT point, so that a part of the rotor kinetic energy is released to balance the electric power absorbed by the low-speed load shedding wind turbines, so that the output of the wind farm does not decrease.

[0120] Therefore, in the high wind speed case, the method of the present application only needs to control part of the wind turbines to shed load when the load disturbance occurs, so that the output of the wind farm does not decrease, the lowest point of the frequency is improved, and the frequency characteristics of the system are improved.

[0121] In summary, the beneficial effects of the present application are as follows:

[0122] 1. The present application adopts the speed load shedding control to configure the reserve capacity of the wind farm, so that the wind turbines can quickly adjust the reserve capacity thereof.

[0123] 2. The method of the present application can meet the requirement of the load shedding reserve capacity in the low wind speed case, while making the wind farm output more wind power, and improving the economy of the wind farm.

[0124] 3. The method of the present application can improve the lowest point of the frequency and improve the frequency characteristics of the system when the disturbance occurs in the high wind speed case.

[0125] 4. The method of the present application only needs to control part of the wind turbines, so that the complexity of the control is simplified.

[0126] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0127] Figure 16 is a structural schematic diagram of the wind farm reserve frequency modulation capacity control device provided by the embodiment of the present application. Figure 16 As shown, in some embodiments, the wind farm reserve frequency modulation capacity control device 16 comprises:

[0128] The acquisition module 1610 is configured to receive a dispatch instruction issued by a wind farm control center and acquire wind speeds of the wind turbines.

[0129] The determination module 1620 is configured to determine a load shedding mode of each wind turbine according to the wind speed of the wind turbine; wherein the load shedding mode of the wind turbine with a wind speed less than a first preset threshold is an overspeed load shedding mode, and the load shedding mode of the wind turbine with a wind speed greater than a second preset threshold is a low-speed load shedding mode; wherein the second preset threshold is greater than or equal to the first preset threshold.

[0130] The calculation module 1630 is configured to determine a load shedding power of each wind turbine according to the wind speed of the wind turbine and the dispatch load shedding power indicated by the dispatch instruction.

[0131] The load shedding module 1640 is configured to perform load shedding on each wind turbine according to the load shedding mode of the wind turbine and the load shedding power of the wind turbine.

[0132] Optionally, the load shedding module 1640 is specifically configured to determine a speed adjustment amount of each wind turbine according to the load shedding power of the wind turbine, and calculate a power reference amount input into each wind turbine according to a current speed of the wind turbine and the speed adjustment amount of the wind turbine.

[0133] Optionally, the wind farm reserve frequency modulation capacity control device 16 further comprises a constraint module configured to determine a speed safety constraint interval corresponding to each wind turbine according to the load shedding mode of the wind turbine; wherein the speed safety constraint interval of the low-speed load shedding mode is smaller than the speed safety constraint interval of the overspeed load shedding mode.

[0134] Optionally, the calculation module 1630 is specifically configured to select a load shedding wind turbine according to the dispatch load shedding power indicated by the dispatch instruction, the wind speed of each wind turbine and a preset selection condition, and determine a load shedding power of the load shedding wind turbine.

[0135] Optionally, the preset selection condition is to select according to the wind speed. Correspondingly, the calculation module 1630 is specifically configured to select from the wind turbine with the smallest wind speed, until the sum of the maximum load shedding powers of the selected wind turbines exceeds the dispatch load shedding power, and then mark the selected wind turbines as the load shedding wind turbines.

[0136] Optionally, the preset selection condition is to ensure the minimum number of wind turbine controls. Correspondingly, the calculation module 1630 is specifically configured to determine all wind turbine combination schemes exceeding the dispatch load shedding power, and mark the wind turbines in the wind turbine combination scheme with the minimum number of wind turbine controls as the load shedding wind turbines in the wind turbine combination schemes exceeding the dispatch load shedding power.

[0137] Optionally, the calculation module 1630 is specifically configured to:

[0138]

[0139] Wherein, i is the serial number of the fan, the first fan is the first fan n 1 fan is a load reduction fan, Δ P dzmi is the maximum load reduction power of the i fan, P d is the dispatch load reduction power, Δ P dzi is the load reduction power of each fan.

[0140] Optionally, the second preset threshold is greater than the first preset threshold. The determination module 1620 is specifically configured to set the load reduction mode of the fan with the wind speed not less than the first preset threshold and not greater than the second preset threshold as the overspeed load reduction mode or the low-speed load reduction mode.

[0141] The wind farm backup frequency modulation capacity control device provided by the embodiment can be used to execute the above-mentioned method embodiments, and has similar implementation principles and technical effects. The embodiment will not be described here again.

[0142] Figure 17 is a schematic diagram of the control device provided by the embodiment. As shown in Figure 17 , the control device 17 provided by one embodiment of the application includes a processor 1700, a memory 1710, and a computer program 1720 stored in the memory 1710 and executable on the processor 1700. The processor 1700 executes the computer program 1720 to implement the steps in each of the above-mentioned wind farm backup frequency modulation capacity control method embodiments, such as Figure 2 steps 210 to 240. Alternatively, the processor 1700 executes the computer program 1720 to implement the functions of each module / unit in each of the above-mentioned system embodiments, such as Figure 16 the functions of the modules 1610 to 1640.

[0143] For example, the computer program 1720 can be divided into one or more modules / units, which are stored in the memory 1710 and executed by the processor 1700 to complete the application. One or more modules / units can be a series of computer program instruction segments that can complete a specific function, which are used to describe the execution process of the computer program 1720 in the control device 17.

[0144] The control device 17 can be a physical control device, a cloud control device, a control device cluster, etc., which is not limited here. The terminal can include, but is not limited to, the processor 1700, the memory 1710. Those skilled in the art can understand that Figure 17The example of the control device 17 does not constitute a limitation on the control device 17, and can include more or fewer components than shown, or combine some components, or different components, for example, the terminal can also include an input / output device, a network access device, a bus, etc.

[0145] The processor 1700 can be a central processing unit (CPU), and can also be other general-purpose processors, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0146] The memory 1710 can be an internal storage unit of the control device 17, for example, a hard disk or a memory of the control device 17. The memory 1710 can also be an external storage device of the control device 17, for example, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. Further, the memory 1710 can include both an internal storage unit and an external storage device of the control device 17. The memory 1710 is used to store computer programs and other programs and data required by the terminal. The memory 1710 can also be used to temporarily store data that has been output or will be output.

[0147] The embodiment of the present application provides a computer readable storage medium, the computer readable storage medium stores a computer program, and the computer program is executed by a processor to realize the steps in the wind farm reserve frequency modulation capacity control method embodiment.

[0148] The computer readable storage medium stores a computer program 1720, the computer program 1720 includes program instructions, the program instructions are executed by the processor 1700 to realize all or part of the processes in the above-mentioned embodiment methods, and the related hardware can also be completed by the computer program 1720. The computer program 1720 can be stored in a computer readable storage medium. When the computer program 1720 is executed by the processor 1700, the steps of each method embodiment described above can be realized. The computer program 1720 includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms. The computer readable medium can include any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content included in the computer readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunication signals.

[0149] The computer readable storage medium can be an internal storage unit of the terminal of any of the preceding embodiments, for example, a hard disk or a memory of the terminal. The computer readable storage medium can also be an external storage device of the terminal, for example, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the terminal. Further, the computer readable storage medium can include both the internal storage unit and the external storage device of the terminal. The computer readable storage medium is used to store computer programs and other programs and data required by the terminal. The computer readable storage medium can also be used to temporarily store data that has been output or will be output.

[0150] It should be understood that the size of the serial number of each step in the above-mentioned embodiments does not mean the order of execution, the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0151] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is exemplified, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be realized in the form of hardware or software function unit. In addition, the specific name of each functional unit and module is only for the convenience of mutual distinction, and does not limit the protection scope of the present application. The specific working process of the unit and module in the above system can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

[0152] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the related description of other embodiments.

[0153] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0154] In the embodiments provided by the present application, it should be understood that the disclosed apparatus / terminal and method can be implemented by other ways. For example, the above-mentioned apparatus / terminal embodiments are only schematic, and the division of the modules or units is only a logical function division, and there can be another division way in actual implementation, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0155] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or they can be distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0156] In addition, each function unit in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software function unit.

[0157] If the integrated module / unit is realized in the form of a software function unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above-mentioned embodiment methods can also be completed by a computer program instructing related hardware, and the computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of each method embodiment described above can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or some intermediate forms, etc. The computer-readable medium can include any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0158] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present application, and should be included in the protection scope of the present application.

Claims

1. A method for controlling reserve frequency regulation capacity of a wind farm, characterized by, The method comprises the following steps: receiving a dispatch instruction issued by a wind farm control center and obtaining wind speeds of wind turbines; determining a load shedding mode of each wind turbine according to the wind speeds of the wind turbines; wherein the load shedding mode of a wind turbine with a wind speed less than a first preset threshold is an overspeed load shedding mode, and the load shedding mode of a wind turbine with a wind speed greater than a second preset threshold is a low-speed load shedding mode; wherein the second preset threshold is greater than or equal to the first preset threshold; determining a load shedding power of each wind turbine according to the wind speeds of the wind turbines and a dispatch load shedding power indicated by the dispatch instruction; shedding load of each wind turbine according to the load shedding mode of each wind turbine and the load shedding power of each wind turbine; shedding load of each wind turbine according to the load shedding mode of each wind turbine and the load shedding power of each wind turbine, comprising: determining a speed adjustment amount of each wind turbine according to the load shedding power of each wind turbine; calculating a power reference amount input into each wind turbine according to a current speed of each wind turbine and the speed adjustment amount of each wind turbine; after determining the load shedding mode of each wind turbine according to the wind speeds of the wind turbines, further comprising: determining a speed safety constraint interval corresponding to each wind turbine according to the load shedding mode of each wind turbine; wherein the speed safety constraint interval of the low-speed load shedding mode is smaller than the speed safety constraint interval of the overspeed load shedding mode.

2. The wind farm reserve frequency control capacity method according to claim 1, characterized in that, determining the load shedding power of each wind turbine according to the wind speeds of the wind turbines and the dispatch load shedding power indicated by the dispatch instruction, comprising: selecting a load shedding wind turbine according to the dispatch load shedding power indicated by the dispatch instruction, the wind speeds of the wind turbines and a preset selection condition, and determining a load shedding power of the load shedding wind turbine.

3. The wind farm reserve frequency control capacity method according to claim 2, characterized in that, The preset selection condition is selected according to the wind speed. selecting a load shedding wind turbine according to the dispatch load shedding power indicated by the dispatch instruction, the wind speeds of the wind turbines and a preset selection condition, and determining a load shedding power of the load shedding wind turbine, comprising: starting from the wind turbine with the smallest wind speed, until the sum of the maximum load shedding powers of the selected wind turbines exceeds the dispatch load shedding power, the selected wind turbines are taken as the load shedding wind turbines; or, the preset selection condition is to ensure the minimum number of wind turbine controls. selecting a load shedding wind turbine according to the dispatch load shedding power indicated by the dispatch instruction, the wind speeds of the wind turbines and a preset selection condition, and determining a load shedding power of the load shedding wind turbine, comprising: determining all wind turbine combination schemes exceeding the dispatch load shedding power; in the wind turbine combination schemes exceeding the dispatch load shedding power, marking the wind turbines in the wind turbine combination scheme with the minimum number of wind turbine controls as the load shedding wind turbines.

4. The wind farm reserve frequency control capacity method according to claim 3, characterized in that, determining the load shedding power of each wind turbine according to the wind speeds of the wind turbines and the dispatch load shedding power indicated by the dispatch instruction, comprising: Wherein, i is the serial number of the fan, the first fan to the nth fan is the load reduction fan, ΔP dzmi is the maximum load reduction power of the ith fan, P d is the scheduling load reduction power, ΔP dzi is the load reduction power of each fan.

5. The wind farm reserve frequency control capacity method according to claim 1, characterized in that, the second preset threshold is greater than the first preset threshold; determining the load shedding mode of each wind turbine according to the wind speeds of the wind turbines, comprising: setting the load shedding mode of a wind turbine with a wind speed not less than the first preset threshold and not greater than the second preset threshold as the overspeed load shedding mode or the low-speed load shedding mode.

6. A control device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program to realize the steps of the wind farm reserve frequency modulation capacity control method in any one of claims 1 to 5.

7. A doubly-fed wind power generation system characterized by comprising: The method comprises the following steps: The wind turbine, the rotating shaft, the generator and the control device as claimed in claim 6. The control device is connected with the wind turbine, the rotating shaft and the generator respectively.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by the processor to realize the steps of the wind farm backup frequency modulation capacity control method in any one of claims 1 to 5.

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