A frequency modulation control method, device, equipment and storage medium for a wind turbine

Abstract

The present invention discloses a frequency modulation control method, device, equipment and storage medium for a wind turbine generator set, including: when a frequency accident occurs to a wind turbine generator set operating stably at the overspeed load shedding point, performing adaptive primary frequency modulation according to the real-time wind speed and the grid frequency deviation, so as to change the rotational speed of the rotor in the wind turbine generator set; during the process of the rotational speed of the rotor in the wind turbine generator set recovering, according to the load shedding power tracking curve of the wind turbine generator set, obtaining the maximum value of the rotational speed among the ideal operating point rotational speed and the actual rotational speed and taking it as the operating rotational speed of the wind turbine generator set, thereby completing the primary frequency modulation of the wind turbine generator set. The present invention can enable the wind turbine to release more active power, delay the process of the active power output of the wind turbine decreasing from the maximum value to the steady state value, effectively alleviate the problem of secondary voltage dip of the system, and solve the technical problems in the prior art that the load shedding power of the wind turbine generator set cannot be adjusted in time and the secondary voltage dip of the power system cannot be alleviated during the frequency modulation of the wind turbine.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and particularly to a frequency modulation control method, device, equipment and storage medium for a wind turbine generator set. Background Art

[0002] A wind turbine generator is connected to the main power grid through power electronic equipment. Since the rotation of the wind turbine rotor is decoupled from the frequency change on the grid side, there is no direct connection between the mechanical kinetic energy of the wind turbine and the grid frequency, and it cannot provide inertia like a synchronous generator. With the continuous increase in the penetration rate of wind power, the volatility and uncertainty of wind power have posed a threat to the safe, stable and reliable operation of the power system.

[0003] Currently, the most commonly used typical overspeed load shedding frequency modulation strategy for wind turbines is achieved through load shedding control and droop control, but it cannot adjust the load shedding power of the wind turbine in a timely manner. During the process of rotor deceleration, the active power corresponding to the load shedding tracking curve of the wind turbine continuously decreases, which is very likely to result in a relatively small active power reference, making it difficult to fully utilize the reserve capacity, weakening the frequency support effect of the wind turbine, and unable to fully exert the frequency modulation ability of the wind turbine generator set. At the same time, the excessive instantaneous power drop during the speed recovery process will bring about a secondary frequency dip problem.

[0004] Therefore, there is an urgent need for a frequency modulation control method that can timely adjust the load shedding power of the wind turbine and alleviate the secondary dip of the power system when performing frequency modulation on the wind turbine generator set. Summary of the Invention

[0005] The present invention provides a frequency modulation control method, device, equipment and storage medium for a wind turbine generator set to solve the technical problem in the prior art that the load shedding power of the wind turbine generator set cannot be adjusted in a timely manner and the secondary dip of the power system cannot be alleviated when performing frequency modulation on the wind turbine.

[0006] To solve the above technical problem, an embodiment of the present invention provides a frequency modulation control method for a wind turbine generator set, including:

[0007] When a frequency accident occurs to a wind turbine generator set operating stably at the overspeed load shedding point, perform adaptive primary frequency modulation according to the real-time wind speed and the grid frequency deviation to change the rotation speed of the rotor in the wind turbine generator set;

[0008] During the process of the rotation speed of the rotor in the wind turbine generator set recovering, obtain the maximum value of the rotation speed between the ideal operating point rotation speed and the actual rotation speed according to the load shedding power tracking curve of the wind turbine generator set, and use it as the operating rotation speed of the wind turbine generator set, thereby completing the primary frequency modulation of the wind turbine generator set.

[0009] As a preferred solution, the performing adaptive primary frequency modulation according to the real-time wind speed and the frequency deviation to change the rotation speed of the rotor in the wind turbine generator set is specifically:

[0010] Obtain the initial load reduction coefficient of the wind turbine operating at the overspeed load shedding point in steady state, and calculate the actual load reduction coefficient of the wind turbine according to the grid frequency deviation;

[0011] Obtain the initial wind energy utilization coefficient of the wind turbine, and calculate the actual wind energy utilization coefficient according to the actual load reduction coefficient;

[0012] Calculate the cubic coefficient of the rotational speed of the load reduction power tracking curve of the wind turbine according to the actual wind energy utilization coefficient and the tip speed ratio of the wind turbine operating at the overspeed load shedding point in steady state; wherein, the tip speed ratio is determined by the real-time wind speed;

[0013] Calculate the reference value of the active power output by the wind turbine according to the cubic coefficient of the rotational speed, and then perform adaptive primary frequency modulation on the wind turbine to change the rotational speed of the rotor in the wind turbine.

[0014] As a preferred solution, the calculation expression of the actual load reduction coefficient of the wind turbine is:

[0015] d′%=d%+Δd%

[0016]

[0017]

[0018] wherein, d′% is the actual load reduction coefficient, d% is the initial load reduction coefficient, ΔP is the standby power used for the primary frequency modulation control of the wind turbine, P opt is the power selected for the primary frequency modulation control of the wind turbine, K1 is the proportional coefficient between Δd% and Δf * Δf * is the grid frequency deviation, Δf max * is the maximum value of the grid frequency deviation.

[0019] As a preferred solution, the calculation expression of the actual wind energy utilization coefficient is:

[0020] C p ′=(1-d′%)C pmax

[0021] wherein, C pmax is the maximum value of the initial wind energy utilization coefficient, C p ′ is the actual wind energy utilization coefficient.

[0022] As a preferred solution, the calculation expression of the cubic coefficient of the rotational speed is:

[0023]

[0024]

[0025] Among them, k′(C p ′, λ′) is the coefficient of the cube of the rotational speed, ρ is the air density, ω′ is the rotor speed corresponding to λ′ during the operation of the wind turbine, v is the real-time wind speed, λ′ is the tip speed ratio of the wind turbine, and R is the radius of the wind turbine blade surface.

[0026] As a preferred solution, the calculation expression of the reference value of the active power output by the wind turbine is:

[0027] P ref =k′(C p ′, λ′)ω′

[0028] Among them, P ref is the reference value of the active power output by the wind turbine, and ω′ is the rotor speed corresponding to λ′ during the operation of the wind turbine.

[0029] Correspondingly, the present invention also provides a frequency modulation control device for a wind turbine, including: a frequency modulation module and a speed recovery module;

[0030] The frequency modulation module is used to perform adaptive primary frequency modulation according to the real-time wind speed and the grid frequency deviation when a frequency accident occurs to a wind turbine operating stably at the overspeed load shedding point, so as to change the rotational speed of the rotor in the wind turbine;

[0031] The speed recovery module is used to obtain and take the maximum value of the rotational speed between the ideal operating point rotational speed and the actual rotational speed according to the load shedding power tracking curve of the wind turbine during the process of the rotational speed recovery of the rotor in the wind turbine as the operating rotational speed of the wind turbine, thereby completing the primary frequency modulation of the wind turbine.

[0032] As a preferred solution, the performing adaptive primary frequency modulation according to the real-time wind speed and the frequency deviation to change the rotational speed of the rotor in the wind turbine specifically includes:

[0033] Obtaining the initial load shedding coefficient of a wind turbine operating stably at the overspeed load shedding point, and calculating the actual load shedding coefficient of the wind turbine according to the grid frequency deviation;

[0034] Obtaining the initial wind energy utilization coefficient of the wind turbine, and calculating the actual wind energy utilization coefficient according to the actual load shedding coefficient;

[0035] Calculating the coefficient of the cube of the rotational speed of the load shedding power tracking curve of the wind turbine according to the actual wind energy utilization coefficient and the tip speed ratio of the wind turbine operating stably at the overspeed load shedding point; wherein, the tip speed ratio is determined by the real-time wind speed;

[0036] Calculate the reference value of the active power output of the wind turbine according to the cubic coefficient of the rotational speed, and then perform adaptive primary frequency modulation on the wind turbine to change the rotational speed of the rotor in the wind turbine.

[0037] As a preferred solution, the calculation expression of the actual load reduction coefficient of the wind turbine is:

[0038] d′% = d% + Δd%

[0039]

[0040]

[0041] where d% is the initial load reduction coefficient, ΔP is the reserve power used for the primary frequency modulation control of the wind turbine, P opt is the power selected for the primary frequency modulation control of the wind turbine, K1 is the proportional coefficient between Δd% and Δf * , Δf * is the power grid frequency deviation, Δf max * is the maximum value of the power grid frequency deviation.

[0042] As a preferred solution, the calculation expression of the actual wind energy utilization coefficient is:

[0043] C p ′ = (1 - d′%)C pmax

[0044] where C pmax is the maximum value of the initial wind energy utilization coefficient, C p ′ is the actual wind energy utilization coefficient.

[0045] As a preferred solution, the calculation expression of the cubic coefficient of the rotational speed is:

[0046]

[0047]

[0048] where k′(C p ′, λ′) is the cubic coefficient of the rotational speed, ρ is the air density, ω′ is the rotor speed corresponding to λ′ during the operation of the wind turbine, v is the real-time wind speed, λ′ is the tip speed ratio of the wind turbine, and R is the radius of the wind turbine blade surface.

[0049] As a preferred solution, the calculation expression of the reference value of the active power output of the wind turbine is:

[0050] P ref = k′(C p ′, λ′)ω′

[0051] Among them, P ref is the reference value of the active power output by the wind turbine, and ω′ is the rotor speed corresponding to λ′ during the operation of the wind turbine.

[0052] Correspondingly, the present invention also provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the frequency modulation control method of the wind turbine as described in any one of the above.

[0053] As a preferred solution, the present invention also provides a computer-readable storage medium. The computer-readable storage medium includes a stored computer program. Among them, when the computer program runs, it controls the device where the computer-readable storage medium is located to execute the frequency modulation control method of the wind turbine as described in any one of the above.

[0054] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0055] In the technical solution of the present invention, the active power increased by the wind turbine during the process of simulating the primary frequency modulation dynamics is not only proportional to the frequency deviation, but also related to the wind speed. The goal of the fan to perform adaptive primary frequency modulation according to its own ability to capture wind energy under different wind speeds is realized. At the same time, the load reduction power of the fan is effectively reduced, and the power generated by the wind power is fully utilized, which has better economy. During the rotor acceleration process of the wind turbine, the present invention can enable the fan to release more active power, delay the process of the active power output of the fan decreasing from the maximum value to the steady state value, provide auxiliary frequency support for the system, effectively alleviate the problem of secondary voltage dip of the system, and give full play to the frequency support ability of the wind turbine. Description of the Drawings

[0056] Figure 1 : is a typical overspeed load shedding control strategy in the prior art;

[0057] Figure 2 : is a schematic diagram of the typical overspeed load shedding control principle in the prior art;

[0058] Figure 3 : is a flowchart of the steps of a frequency modulation control method for a wind turbine provided by an embodiment of the present invention;

[0059] Figure 4 : is an overspeed load shedding control strategy for tracking the mobile load reduction power curve provided by an embodiment of the present invention;

[0060] Figure 5 : is a flowchart of the calculation steps of adaptive primary frequency modulation in a frequency modulation control method for a wind turbine provided by an embodiment of the present invention;

[0061] Figure 6 : Schematic diagram of the overspeed load shedding control principle of the mobile load shedding power tracking curve provided by the embodiment of the present invention;

[0062] Figure 7 : Circuit diagram of the wind turbine grid connection simulation in the embodiment of the present invention;

[0063] Figure 8 : Frequency relationship diagram of the system when the wind speed remains unchanged in the simulation of the embodiment of the present invention;

[0064] Figure 9 : Relationship diagram of the wind turbine rotor speed when the wind speed remains unchanged in the simulation of the embodiment of the present invention;

[0065] Figure 10 : Relationship diagram between the active power output by the wind turbine rotor speed and the wind turbine when the wind speed remains unchanged in the simulation of the embodiment of the present invention;

[0066] Figure 11 : Frequency relationship diagram of the system when the wind speed gradually changes in the simulation of the embodiment of the present invention;

[0067] Figure 12 : Relationship diagram of the wind turbine rotor speed when the wind speed gradually changes in the simulation of the embodiment of the present invention;

[0068] Figure 13 : Relationship diagram between the active power output by the wind turbine rotor speed and the wind turbine when the wind speed gradually changes in the simulation of the embodiment of the present invention;

[0069] Figure 14 : Schematic diagram of the structure of a frequency modulation control device for a wind turbine provided by the embodiment of the present invention. Detailed implementation manners

[0070] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0071] Existing typical wind turbine overspeed load shedding control strategies such as Figure 1 As shown, on the basis of the load shedding power P del , an additional power ΔP = K w Δf simulating the primary frequency modulation characteristic is introduced to adjust the active power set value of the wind turbine rotor side converter, and its principle is as Figure 2 Shown; where K w Is the droop coefficient, and Δf is the frequency deviation. Before the start of the system frequency drop event, the wind turbine is based on the load shedding power tracking curve in Figure 2Run at point B in the figure. When the system experiences under-frequency, additional power is added to the power tracking reference value. The electromagnetic power of the wind turbine is greater than the mechanical power, and the wind turbine starts to Figure 2 decelerate and run towards point C in del . During the process of rotor deceleration, the active power P corresponding to the load reduction tracking curve of the wind turbine ref constantly decreases, which is very likely to result in a relatively small reference value P of the active power output by the wind turbine generator set,

[0072] Embodiment 1

[0073] Please refer to Figure 3 , a frequency modulation control method for a wind turbine generator set provided by an embodiment of the present invention, including the following steps S101 - S102:

[0074] S101: When a frequency accident occurs to a wind turbine generator set operating stably at the overspeed load reduction point, perform adaptive primary frequency modulation according to the real-time wind speed and the grid frequency deviation, so as to change the rotational speed of the rotor in the wind turbine generator set.

[0075] It should be noted that before a frequency accident occurs in the power system, the wind turbine is in a load reduction operation state, and the load reduction coefficient d% is:

[0076]

[0077] In the formula, P m_del is the mechanical power of the wind turbine during load reduction operation / W; P MPPT is the active power corresponding to the maximum power tracking point of the wind turbine / W.

[0078] When the wind turbine operates stably in the load reduction state, its mechanical power and the reference value of the active power can be respectively expressed as:

[0079]

[0080]

[0081] C p_del = (1 - d%)C pmax

[0082]

[0083] In the formula, S = πR 2 is the area of the wind swept by the wind turbine rotor / m 2 , R is the radius of the wind turbine rotor of the wind turbine generator set; ρ is the air density / kg·m －3 ; v is the wind speed before the air enters the swept surface of the wind turbine / m·s －1 ; λ del is the tip speed ratio during load reduction operation.

[0084] When a frequency fault occurs in a wind turbine generator set, for example, taking the system frequency drop fault as an example, the system frequency of the wind turbine generator set decreases. The wind turbine generator set will perform adaptive primary frequency regulation according to the wind speed and the system frequency offset. By controlling the reference value of the output active power, the kinetic energy stored in the rotor is fully released, and the rotational speed of the wind turbine rotor decreases to support the grid frequency for a short time. For its control strategy, please refer to Figure 4 .

[0085] As a preferred solution, please refer to Figure 5 , and perform adaptive primary frequency regulation according to the real-time wind speed and frequency offset to change the rotational speed of the rotor in the wind turbine generator set, specifically including the following steps S201 - S204:

[0086] S201: Obtain the initial load reduction coefficient of the wind turbine generator set operating stably at the overspeed load reduction point, and calculate the actual load reduction coefficient of the wind turbine generator set according to the grid frequency offset.

[0087] It should be noted that, please refer to Figure 4 , the control strategy defines that the load reduction coefficient adjustment caused by the additional primary frequency regulation control is Δd%, and Δd% is proportional to Δf * , where ΔP is the reserve power used for the primary frequency regulation control of the wind turbine, and K1 is the proportional coefficient between Δd% and Δf * .

[0088] As a preferred solution, the calculation expression of the actual load reduction coefficient of the wind turbine generator set is:

[0089] d′% = d% + Δd%

[0090]

[0091]

[0092] where d′% is the actual load reduction coefficient, d% is the initial load reduction coefficient, ΔP is the reserve power used for the primary frequency regulation control of the wind turbine generator set, P opt is the power selected for the primary frequency regulation control of the wind turbine generator set, K1 is the proportional coefficient between Δd% and Δf * , Δf * is the grid frequency offset, Δf max * is the maximum value of the grid frequency offset; among them, the value of Δf max * is determined by the requirements of the operating frequency range of the wind turbine generator set system.

[0093] At this time, the per-unit value K w * of the regulation power of the wind turbine is:

[0094] S202: Obtain the initial wind energy utilization coefficient of the wind turbine, and calculate the actual wind energy utilization coefficient according to the actual load reduction coefficient.

[0095] As a preferred solution, the calculation expression of the actual wind energy utilization coefficient is:

[0096] C p ′=(1 - d′%)C pmax

[0097] where C pmax is the maximum value of the initial wind energy utilization coefficient, and C p ′ is the actual wind energy utilization coefficient.

[0098] It should be noted that the wind energy utilization coefficient is related to the tip speed ratio λ, so the relationship between C p and λ can be obtained. When C p is known, two corresponding λs can be found according to the C p -λ curve. Under overspeed load reduction control, only the larger λ needs to be retained, and thus the one-to-one correspondence between C p and λ can be obtained.

[0099] S203: Calculate the cubic coefficient of the rotational speed of the load reduction power tracking curve of the wind turbine according to the actual wind energy utilization coefficient and the tip speed ratio of the wind turbine operating in the overspeed load reduction point in the steady state; wherein, the tip speed ratio is determined by the real-time wind speed.

[0100] As a preferred solution, the calculation expression of the cubic coefficient of the rotational speed is:

[0101]

[0102]

[0103] where k′(C p ′,λ′) is the cubic coefficient of the rotational speed, ρ is the air density, ω′ is the rotor rotational speed corresponding to λ′ during the operation of the wind turbine, v is the real-time wind speed, λ′ is the tip speed ratio of the wind turbine, and R is the radius of the wind turbine blade surface.

[0104] It should be noted that according to the C p -λ curve in step S202 and the one-to-one correspondence between C p and λ, the corresponding λ′ can be obtained by looking up the table for the calculated C p ′, and then the cubic coefficient of the rotational speed of the corresponding load reduction power tracking curve at this time can be obtained.

[0105] S204: Calculate the reference value of the active power output by the wind turbine according to the cube coefficient of the rotational speed, and then perform adaptive primary frequency modulation on the wind turbine to change the rotational speed of the rotor in the wind turbine.

[0106] As a preferred solution, the calculation expression of the reference value of the active power output by the wind turbine is:

[0107] P ref =k′(C p ′,λ′)ω′

[0108] Wherein, P ref is the reference value of the active power output by the wind turbine, and ω′ is the rotational speed of the rotor corresponding to λ′ during the operation of the wind turbine.

[0109] S102: During the recovery process of the rotational speed of the rotor in the wind turbine, according to the load shedding power tracking curve of the wind turbine, obtain the maximum value of the rotational speed among the ideal operating point rotational speed and the actual rotational speed, and use it as the operating rotational speed of the wind turbine, thereby completing the primary frequency modulation of the wind turbine.

[0110] It should be noted that when the inertia of the wind turbine is not considered, ω r =ω′, (ω′ is the rotational speed of the rotor corresponding to λ′ during the operation of the wind turbine), at this time, the reference value of the active power output by the wind turbine is equal to the mechanical power, and the expression of the additional active power generated by the wind turbine at a certain moment during the frequency response period is:

[0111]

[0112]

[0113] As can be seen from the above formula, the additional active power generated by the wind turbine during the process of simulating the primary frequency modulation dynamics is not only proportional to the frequency deviation, but also related to the wind speed. Therefore, the control strategy in the embodiments of the present invention achieves the goal of adaptive primary frequency modulation according to the ability of the wind turbine to capture wind energy under different wind speeds. At the same time, during the stage of system frequency decline, in the process of gradual recovery of the system frequency, the improved droop control scheme enables the wind turbine to release more active power, slows down the recovery speed of the rotor speed, and therefore also delays the process of the active power output of the wind turbine decreasing from the maximum value to the steady state value, enabling the wind turbine to fully release active power when the system frequency recovers and providing more frequency support for the system.

[0114] It should be noted that when considering the inertia of the wind turbine, the actual speed ω of the rotor ra will be less than the rotational speed ω corresponding to the ideal operating point r ′. If the ω ra corresponding to the active reference value of the wind turbine becomes ω r' corresponding to the active power reference value of the fan, not only can increase the active power output by the fan during the frequency response process, but also delay the acceleration process of the rotor. From the above analysis, it can be seen that whether in the acceleration or deceleration process, each load shedding power tracking curve corresponds to two speeds, the ideal operating point speed ω r ' and the actual speed ω r . Substitute the maximum speed of the two into the expression of the active power reference value output by the fan. The fan will release more active power, delay the process of the active power output of the fan decreasing from the maximum value to the steady-state value, provide auxiliary frequency support for the system, effectively alleviate the problem of secondary voltage dip of the system, and enable the fan to achieve a better frequency support effect.

[0115] It can be understood that the principle of the control strategy proposed in the embodiment of the present invention is as Figure 6 shown. When simulating the primary frequency modulation dynamic characteristics of the fan, the rotor speed first decreases and then increases, and finally returns to near the original operating point. During the process of rotor deceleration, the operating point of the fan will move along the solid line passing through point 1. Please refer to Figure 4 the improved control strategy shown in the dashed box. By increasing the power set value P ref of the fan during the rotor acceleration process, the frequency support performance of the fan is improved. During the process of rotor acceleration, considering the inertia of the fan, the actual speed ω ra of the rotor will be less than the speed ω r ' corresponding to the ideal operating point. The active power reference value of the fan is the active power P refa corresponding to point 5, and the mechanical power reference value is the power corresponding to point 6. Point 7 is the primary frequency modulation steady-state operating point of the fan. At this time, if ω ra is replaced with ω r ', not only can the active power output by the fan during the frequency response process be increased (the operating point changes from point 5 to point 4, and the active power output by the fan changes from P refa to P ref '), but also the acceleration process of the rotor can be delayed. From the above analysis, it can be seen that whether in the acceleration or deceleration process, each load shedding power tracking curve corresponds to two speeds, the ideal operating point speed ω r ' and the actual speed ω r . Taking the maximum speed of the two, the fan can achieve a better frequency support effect.

[0116] Implementing the above embodiments has the following effects:

[0117] In the technical solution of the present invention, the active power increased during the process of the wind turbine simulating the primary frequency modulation dynamics is not only proportional to the frequency deviation, but also related to the wind speed, achieving the goal of the fan performing adaptive primary frequency modulation according to its own ability to capture wind energy under different wind speeds. At the same time, the load reduction power of the fan is effectively reduced, and the power generated by the wind power is fully utilized, with better economy. During the rotor acceleration process of the wind turbine, the present invention can enable the fan to release more active power, delay the process of the active power output of the fan decreasing from the maximum value to the steady-state value, provide auxiliary frequency support for the system, effectively alleviate the problem of secondary voltage dip of the system, and give full play to the frequency support ability of the wind turbine.

[0118] Embodiment 2

[0119] In the embodiment of the present invention, through the simulation study of the frequency modulation control method of the wind turbine described in Embodiment 1, taking a wind farm with 100 2MW doubly-fed wind turbines connected to the grid through a 100km transmission line as an example, the load connected at the middle section of the line is 240MW + 20Mvar. The specific parameters of the simulation model can be seen in Table 1, and the simulation circuit diagram of the wind turbine grid connection is as Figure 7 shown.

[0120] Table 1

[0121]

[0122]

[0123] Next, simulation experiments of various load reduction control strategies are carried out under the condition of a steady-state wind speed of 8m / s. Set Scheme 1 as the fixed load reduction power tracking curve control strategy, Scheme 2 as the variable load reduction power tracking curve control strategy, and Scheme 3 as the improved control strategy of Scheme 2. The three schemes adopt the same droop coefficient,

[0124] where K1 = -5, and the equivalent unit regulation power is When a load of 10MW + 1Mvar suddenly increases at t = 5s, the simulation results of the dynamic response of the fan and the system frequency response under different overspeed load reduction control frequency modulation schemes are as Figure 8 -10 shown.

[0125] It can be Figure 8 seen that the overspeed load reduction control of the fan has a very strong auxiliary support effect on the system frequency. The effects of Scheme 2 and the improved scheme are the best, and the lowest frequency point is increased from 49.14Hz in the no-control scheme to 49.61Hz. According to Figure 9 、 10 It can be known that the steady-state frequency of the system is 49.92Hz. According to the unit regulation power The steady-state frequency deviation of 0.08 Hz should correspond to an increase in the steady-state active power of the wind turbine by 0.00336 pu. In Scheme 2 and the improved scheme, the steady-state output of the wind turbine meets the expected steady-state frequency response of the system, while the steady-state power of the wind turbine corresponding to Scheme 1 is significantly lower. When the frequency drops, the active power output by the wind turbine increases accordingly. Scheme 1 increases by 0.016 pu, and Scheme 2 and the improved droop control increase by 0.033 pu. It can be seen that the control scheme of the variable load shedding power tracking curve can better explore the frequency support potential of the wind turbine and make the wind turbine generate more active power during the system frequency drop process. During the stage of system frequency decline, there is little difference between Scheme 2 and the improved droop control scheme. However, during the process of system frequency gradual recovery, the wind turbine releases more active power under the improved scheme than under Scheme 2, as shown in Figure 9 the shaded part. According to Figure 10 , the improved scheme slows down the recovery speed of the rotor speed, and thus also delays the process of the active power output of the wind turbine decreasing from the maximum value to the steady-state value, enabling the wind turbine to fully release active power when the system frequency recovers and providing auxiliary frequency support for the system.

[0126] To further verify the effectiveness of the improved control strategy, a set of 120-second fluctuating wind speed data is selected below, and the simulation results under various load shedding control schemes during wind speed fluctuation are obtained, as shown in Figure 11 -13. According to Figure 11 , when the wind turbine adopts the no-control scheme and Scheme 1, the lowest frequency points are both lower than 49 Hz. The lowest frequency points of Scheme 2 and Scheme 3 are 49.21 Hz. It can be seen that the control scheme of the variable load shedding control curve enables the wind turbine to have a stronger frequency support ability. From Figure 12 , 13 , it can be seen that during the entire frequency response process, the change of the rotor speed of the wind turbine is slower under the improved control scheme, and the wind turbine can output more active power. During the two frequency recovery processes, the improved control scheme arrives at the lower limit of the frequency fluctuation 49.8 Hz during normal system operation 4.9 s and 7.7 s earlier than Scheme 2. It can be seen that under the gradually changing wind speed, the improved control strategy enables the wind turbine to have better dynamic frequency regulation ability and makes the system frequency recover to the normal operation range faster.

[0127] Embodiment 3

[0128] Correspondingly, please refer to Figure 14 , the present invention also provides a frequency modulation control device for a wind turbine, including: a frequency modulation module 301 and a speed recovery module 302.

[0129] The frequency modulation module 301 is used to, when a frequency accident occurs to a wind turbine operating in the overspeed load shedding point in the steady state, perform adaptive primary frequency modulation according to the real-time wind speed and the grid frequency deviation, so as to change the speed of the rotor in the wind turbine.

[0130] The rotational speed recovery module 302 is configured to obtain, during the rotational speed recovery process of the rotor in the wind turbine generator set, the maximum value of the rotational speed between the ideal operating point rotational speed and the actual rotational speed according to the load shedding power tracking curve of the wind turbine generator set, and use it as the operating rotational speed of the wind turbine generator set, thereby completing the primary frequency regulation of the wind turbine generator set.

[0131] As a preferred solution, the adaptive primary frequency regulation is performed according to the real-time wind speed and frequency deviation to change the rotational speed of the rotor in the wind turbine generator set, specifically:

[0132] Obtain the initial load shedding coefficient of the wind turbine generator set operating stably at the overspeed load shedding point, and calculate the actual load shedding coefficient of the wind turbine generator set according to the grid frequency deviation; obtain the initial wind energy utilization coefficient of the wind turbine generator set, and calculate the actual wind energy utilization coefficient according to the actual load shedding coefficient; calculate the rotational speed cubic coefficient of the load shedding power tracking curve of the wind turbine generator set according to the actual wind energy utilization coefficient and the tip speed ratio of the wind turbine generator set operating stably at the overspeed load shedding point; wherein, the tip speed ratio is determined by the real-time wind speed; calculate the reference value of the active power output by the wind turbine generator set according to the rotational speed cubic coefficient, and further perform adaptive primary frequency regulation on the wind turbine generator set to change the rotational speed of the rotor in the wind turbine generator set.

[0133] As a preferred solution, the calculation expression of the actual load shedding coefficient of the wind turbine generator set is:

[0134] d′% = d% + Δd%

[0135]

[0136]

[0137] wherein, d% is the initial load shedding coefficient, ΔP is the reserve power used for the primary frequency regulation control of the wind turbine generator set, P opt is the power selected for the primary frequency regulation control of the wind turbine generator set, K1 is the proportional coefficient between Δd% and Δf * between, Δf * is the grid frequency deviation, Δf max * is the maximum value of the grid frequency deviation.

[0138] As a preferred solution, the calculation expression of the actual wind energy utilization coefficient is:

[0139] C p ′ = (1 - d′%)C pmax

[0140] wherein, C pmax is the maximum value of the initial wind energy utilization coefficient, C p′ is the actual wind energy utilization coefficient.

[0141] As a preferred solution, the calculation expression of the cubic coefficient of the rotational speed is:

[0142]

[0143]

[0144] where k′(C p ′, λ′) is the cubic coefficient of the rotational speed, ρ is the air density, ω′ is the real-time rotational speed of the rotor in the wind turbine generator set, v is the real-time wind speed, λ′ is the tip speed ratio of the wind turbine generator set, and R is the radius of the blade surface of the wind turbine generator set.

[0145] As a preferred solution, the calculation expression of the reference value of the active power output by the wind turbine generator set is:

[0146] P ref =k′(C p ′, λ′)ω′

[0147] where P ref is the reference value of the active power output by the wind turbine generator set.

[0148] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the above-described device can refer to the corresponding process in the foregoing method embodiment and will not be elaborated herein.

[0149] Implementing the above embodiments has the following effects:

[0150] The active power increased by the wind turbine generator set in the technical solution of the present invention during the process of simulating primary frequency modulation dynamics is not only proportional to the frequency deviation but also related to the wind speed, achieving the goal of the fan performing adaptive primary frequency modulation according to its own ability to capture wind energy under different wind speeds. At the same time, the load shedding power of the fan is effectively reduced, and the power generated by the wind power is fully utilized, having better economy. During the rotor acceleration process of the wind turbine generator set, the present invention can enable the fan to release more active power, delay the process of the active power output of the fan decreasing from the maximum value to the steady state value, provide auxiliary frequency support for the system, effectively alleviate the problem of secondary voltage dip of the system, and give full play to the frequency support ability of the wind turbine generator set.

[0151] Embodiment III

[0152] Correspondingly, the present invention further provides a terminal device, including: a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the frequency modulation control method of the wind turbine generator set described in any one of the above embodiments.

[0153] The terminal device of this embodiment includes: a processor, a memory, and a computer program and computer instructions stored in the memory and executable on the processor. When the processor executes the computer program, it implements each step in the first embodiment above, such as Figure 1 the steps S101 to S102 shown. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the above device embodiment, such as the frequency modulation module 301.

[0154] Exemplarily, the computer program can be divided into one or more modules / units. The one or more modules / units are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, and this instruction segment is used to describe the execution process of the computer program in the terminal device. For example, the frequency modulation module 301 is used to perform adaptive primary frequency modulation according to the real-time wind speed and grid frequency offset when a frequency accident occurs in a wind turbine operating at a steady state at the overload shedding point, so as to change the rotational speed of the rotor in the wind turbine.

[0155] The terminal device can be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The terminal device may include, but is not limited to, a processor and a memory. Those skilled in the art can understand that the schematic diagram is only an example of the terminal device and does not constitute a limitation on the terminal device. It may include more or fewer components than shown, or combine some components, or different components. For example, the terminal device may further include input / output devices, network access devices, a bus, etc.

[0156] The so-called processor may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), off-the-shelf programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The processor is the control center of the terminal device and connects various parts of the entire terminal device through various interfaces and lines.

[0157] The memory can be used to store the computer programs and / or modules. By running or executing the computer programs and / or modules stored in the memory, and invoking the data stored in the memory, the processor realizes various functions of the terminal device. The memory mainly includes a program storage area and a data storage area. Among them, the program storage area can store an operating system, application programs required for at least one function, etc.; the data storage area can store data created according to the use of the mobile terminal, etc. In addition, the memory can include high-speed random access memory, and can also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, at least one magnetic disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0158] Among them, if the modules / units integrated in the terminal device are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, to implement all or part of the processes in the above-mentioned embodiment methods of the present invention, it can also be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-mentioned various method embodiments can be realized. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a mobile hard disk, a magnetic disk, an optical disc, a computer memory, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), an electrical carrier signal, a telecommunication signal, and a 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.

[0159] Embodiment 4

[0160] Correspondingly, the present invention also provides a computer-readable storage medium, which includes a stored computer program. When the computer program runs, it controls the device where the computer-readable storage medium is located to execute the frequency modulation control method of the wind turbine set described in any one of the above embodiments.

[0161] The specific embodiments described above further elaborate on the object, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. In particular, for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A frequency modulation control method for a wind turbine, characterized in that, Including: When a frequency accident occurs to a wind turbine operating at a steady state at the over-speed load shedding point, adaptive primary frequency modulation is performed according to the real-time wind speed and the grid frequency deviation, so as to change the rotational speed of the rotor in the wind turbine; During the process of the rotational speed of the rotor in the wind turbine recovering, according to the load shedding power tracking curve of the wind turbine, the maximum value of the rotational speed is obtained and taken from among the ideal operating point rotational speed and the actual rotational speed as the operating rotational speed of the wind turbine, thereby completing the primary frequency modulation of the wind turbine; Among them, the performing of adaptive primary frequency modulation according to the real-time wind speed and frequency deviation so as to change the rotational speed of the rotor in the wind turbine is specifically: Obtain the initial load shedding coefficient of a wind turbine operating at a steady state at the over-speed load shedding point, and calculate the actual load shedding coefficient of the wind turbine according to the grid frequency deviation; Obtain the initial wind energy utilization coefficient of the wind turbine, and calculate the actual wind energy utilization coefficient according to the actual load shedding coefficient; According to the actual wind energy utilization coefficient and the tip speed ratio of the wind turbine operating at a steady state at the over-speed load shedding point, calculate the cubic coefficient of the rotational speed of the load shedding power tracking curve of the wind turbine; wherein, the tip speed ratio is determined by the real-time wind speed; According to the cubic coefficient of the rotational speed, calculate the reference value of the active power output by the wind turbine, and further perform adaptive primary frequency modulation on the wind turbine so as to change the rotational speed of the rotor in the wind turbine.

2. The frequency modulation control method of a wind turbine unit according to claim 1, characterized in that, The calculation expression of the actual load shedding coefficient of the wind turbine is: d′% = d% + Δd% Among them, d′% is the actual load reduction coefficient, d% is the initial load reduction coefficient, ΔP is the standby power used for the primary frequency regulation control of the wind turbine, and P opt is the power selected for the primary frequency regulation control of the wind turbine, K1 is the proportional coefficient between Δd% and Δf * and Δf * is the power grid frequency deviation, and Δf max * is the maximum value of the power grid frequency deviation.

3. A frequency modulation control method for a wind turbine unit according to claim 2, characterized in that, The calculation expression of the actual wind energy utilization coefficient is: C p C' = (1 - d'% )C pmax Among them, C pmax is the maximum value of the initial wind energy utilization coefficient, and C p ' is the actual wind energy utilization coefficient.

4. The frequency modulation control method of a wind turbine unit according to claim 3, characterized in that, The calculation expression of the cubic coefficient of the rotational speed is: where k′(C p ′, λ′) is the coefficient of the cube of the rotational speed, ρ is the air density, ω′ is the rotor speed corresponding to λ′ during the operation of the wind turbine, v is the real-time wind speed, λ′ is the tip speed ratio of the wind turbine, and R is the radius of the wind turbine blade surface.

5. The frequency modulation control method of a wind turbine unit according to claim 4, characterized in that, The calculation expression of the reference value of the active power output by the wind turbine is: P ref = k′(C p ′, λ′)ω′ Among them, P ref is the reference value of the active power output by the wind turbine, and ω′ is the rotor speed corresponding to λ′ during the operation of the wind turbine.

6. A frequency modulation control device for a wind turbine, characterized in that, Including: A frequency modulation module and a rotational speed recovery module; The frequency modulation module is used for, when a frequency accident occurs to a wind turbine operating at a steady state at the over-speed load shedding point, performing adaptive primary frequency modulation according to the real-time wind speed and the grid frequency deviation so as to change the rotational speed of the rotor in the wind turbine; The rotational speed recovery module is used for, during the process of the rotational speed of the rotor in the wind turbine recovering, according to the load shedding power tracking curve of the wind turbine, obtaining the maximum value of the rotational speed and taking it from among the ideal operating point rotational speed and the actual rotational speed as the operating rotational speed of the wind turbine, thereby completing the primary frequency modulation of the wind turbine; Among them, the performing of adaptive primary frequency modulation according to the real-time wind speed and frequency deviation so as to change the rotational speed of the rotor in the wind turbine is specifically: Obtain the initial load shedding coefficient of a wind turbine operating at a steady state at the over-speed load shedding point, and calculate the actual load shedding coefficient of the wind turbine according to the grid frequency deviation; Obtain the initial wind energy utilization coefficient of the wind turbine, and calculate the actual wind energy utilization coefficient according to the actual load shedding coefficient; According to the actual wind energy utilization coefficient and the tip speed ratio of the wind turbine operating at a steady state at the over-speed load shedding point, calculate the cubic coefficient of the rotational speed of the load shedding power tracking curve of the wind turbine; wherein, the tip speed ratio is determined by the real-time wind speed; According to the cubic coefficient of the rotational speed, calculate the reference value of the active power output by the wind turbine generator set, and then perform adaptive primary frequency modulation on the wind turbine generator set to change the rotational speed of the rotor in the wind turbine generator set.

7. A terminal device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the frequency modulation control method of the wind turbine generator set according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein when the computer program runs, it controls the device where the computer-readable storage medium is located to execute the frequency modulation control method of the wind turbine generator set according to any one of claims 1 to 5.

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