Target type pitch angle cooperative control method and system for sending end power grid frequency rising problem and medium

Abstract

The invention relates to the technical field of power system control, and discloses a wind turbine generator target type pitch angle cooperative control method and system for the high-frequency problem of a sending-end power grid and a medium. According to the wind turbine generator target pitch angle cooperative control method for the high-frequency problem of the sending-end power grid, target pitch angle control is adopted, and a plurality of target values of wind turbine generator pitch angle changes participating in high-frequency problem adjustment can be determined, so that the active output of a wind power plant is reduced at the fastest speed, the output of the wind turbine generator is reduced more quickly, and the wind power generation efficiency is improved. The frequency rising trend is effectively slowed down, the rotating speed of the rotor is improved in cooperation with rotor kinetic energy control, the rotating speed of the rotor can be effectively improved after the frequency crosses the highest point, and the pitch angle is kept at a large value, so that the frequency modulation participation time of the wind turbine generator is remarkably prolonged, the frequency maximum value can be more effectively reduced, and the frequency tends to be gentle more quickly; and the control effect of wind power participating in high-frequency regulation of the sending-end power grid is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power system control, and particularly relates to power system stability and control technology, and particularly relates to a wind turbine target type pitch angle cooperative control method, system and medium for a high frequency problem of a sending end power grid. BACKGROUND

[0002] The proportion of wind power in the power grid is growing, the system inertia is continuously decreasing, and the frequency modulation capability of the power grid is gradually weakened. Wind power has considerable potential in frequency regulation due to its ease of control and centralized grid connection. Many countries and regions have issued grid specifications requiring wind power to have the ability to participate in frequency regulation.

[0003] Unlike the frequency modulation control strategy of the receiving end power grid, the frequency change of the receiving end power grid is mainly due to the increase of the receiving end load, resulting in a frequency drop, while the sending end power grid faces the problem of frequency rise. The frequency modulation method used in traditional receiving end power grid control is to increase the frequency, which usually lasts for a short time, for example, about 5s-10s, and is difficult to achieve long-term frequency modulation and maintenance, and cannot be used in the sending end power grid.

[0004] The existing technology has studied the frequency modulation control strategy of wind turbines under the condition of power grid frequency drop. These strategies mainly focus on the frequency drop of the receiving end power grid due to power shortage. However, the sending end power grid, as the source of power output, faces the problem of power surplus caused by sending line faults and other events, which in turn leads to system frequency rise. The control strategy currently adopted for the high frequency problem of the sending end power grid is relatively simple, such as using the high frequency load shedding or rapid generator tripping of synchronous generators, without fully utilizing other adjustable resources such as wind power. If the wind turbine frequency modulation control suitable for frequency drop is directly applied to the high frequency scenario of the sending end power grid, the frequency modulation effect may not be guaranteed. Because in the low frequency scenario, if no standby power is reserved, the wind turbine cannot continuously increase the power. SUMMARY

[0005] In view of the technical problems of the existing technology for frequency modulation control of the high frequency problem of the sending end power grid, the present application aims to provide a wind turbine target type pitch angle cooperative control method for the high frequency problem of the sending end power grid. By using target type pitch angle control, a number of target values of the pitch angle change of the wind turbine participating in the high frequency problem adjustment can be determined, so as to reduce the active power output of the wind farm at the fastest speed, reduce the wind turbine output more quickly, effectively slow down the frequency rise trend, and cooperate with the rotor kinetic energy control to increase the rotor speed. After the frequency passes the highest point, the rotor speed can be effectively increased, the pitch angle can be maintained at a larger value, thereby significantly prolonging the time of the wind turbine participating in frequency modulation, more effectively reducing the maximum frequency, and making the frequency tend to be flat more quickly, and improving the control effect of wind power participating in the high frequency regulation of the sending end power grid.

[0006] According to the first aspect of the object of the present application, a wind turbine target pitch angle collaborative control method for power grid high frequency problem is provided, comprising the following steps:

[0007] Step 1, continuously monitoring the frequency and frequency fluctuation of the sending end power grid;

[0008] Step 2, in response to the frequency fluctuation of the sending end power grid exceeding the control dead zone, starting the rotor kinetic energy control and the pitch angle control collaborative control, wherein: reducing the active power output through the rotor kinetic energy control; at the same time, increasing the pitch angle at the maximum change rate through the pitch angle control; during the rotor kinetic energy control response and the pitch angle control collaborative control, continuously monitoring the frequency of the sending end power grid and the speed of the wind turbine, and locking the frequency deviation input of the pitch angle control;

[0009] Step 3, continuously monitoring whether the frequency of the sending end power grid rises to the set maximum value and whether the pitch angle of the wind turbine rises to the set maximum value, if both are no, continue to increase the pitch angle at the maximum change rate and lock the frequency deviation input of the pitch angle control;

[0010] Step 4, if the pitch angle reaches the set maximum value first, keep the maximum value unchanged and control the wind turbine to operate according to the maximum value of the pitch angle;

[0011] If the frequency of the sending end power grid reaches the set maximum value first, calculate the maximum frequency deviation at the maximum value of the frequency of the sending end power grid, and calculate the pitch angle size at the maximum frequency deviation combined with the target pitch angle algorithm, and take it as the first target value of the pitch angle control, control to increase the pitch angle to the first target value at the maximum change rate and keep it unchanged, and the wind turbine operates according to the first target value of the pitch angle;

[0012] Step 5, during the rotor kinetic energy control response and the pitch angle control collaborative control, continuously monitoring the speed of the wind turbine: when the speed drops does not reach the preset value, executing the pitch angle control according to the step 4; if the speed drops reaches the preset value, exiting the rotor kinetic energy control and the pitch angle control collaborative control;

[0013] Step 6: in response to exiting the rotor kinetic energy control and the pitch angle control collaborative control, calculating the second target value of the pitch angle control at the real-time frequency deviation according to the target pitch angle algorithm, and controlling the pitch angle to fall back to the second target value at the fastest change rate from the current value, and still continuously monitoring the frequency and speed during the pitch angle falling back, and locking the frequency deviation input of the pitch angle control.

[0014] Step 7, in response to the pitch angle falling to the second target value, open the frequency deviation input of the pitch angle control, so that the pitch angle size will change with the frequency deviation, gradually transition to the stable value and no longer change, thus completing the frequency modulation control of the sending end power grid.

[0015] According to the second aspect of the object of the present application, a computer system is further provided, comprising:

[0016] one or more processors; and

[0017] a memory storing instructions operable;

[0018] wherein the instructions, when executed by the one or more processors, cause the aforementioned one or more processors to perform operations comprising executing the process of the wind turbine target pitch angle cooperative control method of the aforementioned embodiments.

[0019] According to the third aspect of the object of the present application, a computer readable storage medium is further provided for storing one or more programs, the one or more programs comprising instructions or instruction sets executable by one or more processors;

[0020] wherein the instructions or instruction sets, when executed by the one or more processors, execute the process of the wind turbine target pitch angle cooperative control method of the aforementioned embodiments.

[0021] In combination with the wind turbine target pitch angle cooperative control method for the high frequency problem of the power grid according to the embodiments of the present application, on the one hand, by adopting target pitch angle control, the wind turbine output can be reduced faster than the existing pitch angle control, effectively slowing down the frequency rising trend; on the other hand, cooperating with the rotor kinetic energy control, the rotor speed can be effectively increased after the frequency passes the highest point, so that the pitch angle can be maintained at a larger value, thereby significantly prolonging the time of the wind turbine participating in frequency modulation, which can more effectively reduce the maximum frequency and make the frequency tend to be flat faster, and plays an important role in improving the control effect of wind power participating in the high frequency regulation of the sending end power grid. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical, or nearly identical, component that is illustrated in various figures is represented with a like numeral. For purposes of clarity, not every component is called out in every drawing. Embodiments of various aspects of the present application will now be described, by way of example only, with reference to the drawings.

[0023] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical, or nearly identical, component that is illustrated in various figures is represented with a like numeral. For purposes of clarity, not every component is called out in every drawing. Embodiments of various aspects of the present application will now be described, by way of example only, with reference to the drawings. Figure 1 is a flow chart of the wind turbine target pitch angle cooperative control method for the high frequency problem of the sending end power grid according to the embodiments of the present application.

[0024] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical, or nearly identical, component that is illustrated in various figures is represented with a like numeral. For purposes of clarity, not every component is called out in every drawing. Embodiments of various aspects of the present application will now be described, by way of example only, with reference to the drawings. Figure 2is a four-machine two-area simulation system diagram containing wind turbines according to an embodiment of the present application.

[0025] attached Figure 3 is a comprehensive inertia control block diagram according to an embodiment of the present application.

[0026] attached Figure 4 is an exponential function fitting diagram of the pitch angle of the wind turbine under different active power outputs according to an embodiment of the present application.

[0027] attached Figure 5 is a targetless pitch angle control block diagram.

[0028] attached Figure 6 is a single wind turbine output change curve diagram under different control strategies.

[0029] attached Figure 7 is a rotor speed change curve diagram under different control strategies.

[0030] attached Figure 8 is a pitch angle change curve diagram under different control strategies.

[0031] attached Figure 9 is a system frequency change curve diagram under different control strategies.

[0032] attached Figure 10 is a single wind turbine output change curve diagram under targetless pitch angle cooperative control.

[0033] attached Figure 11 is a rotor speed change curve diagram under targetless pitch angle cooperative control.

[0034] attached Figure 12 is a system frequency change curve diagram under targetless pitch angle cooperative control. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0036] Aspects of the present application are described in the context of the disclosed embodiments with reference to the drawings. The disclosed embodiments are not necessarily intended to include all aspects of the present application. It is understood that various concepts and embodiments introduced in the above detailed description of the disclosed embodiments and the concepts and embodiments made in the following detailed description of other various embodiments can be implemented in any of the several embodiments of the application, and that such introduced concepts and embodiments can be combined with each other in otherwise variant ways, and that such introduced concepts and embodiments can be without limitation implemented in various applications and using a plurality of structures, concepts, and embodiments other than the specific embodiments presented in the foregoing and following detailed description and associated drawings.

[0037] {Example 1}

[0038] In conjunction Figure 1 and Figures 2-4 As shown in the figure, the wind turbine target pitch angle collaborative control method for the sending end power grid high frequency problem according to the embodiment of the present application includes the following steps:

[0039] Step 1, continuously monitor the frequency and frequency fluctuation of the sending end power grid;

[0040] Step 2, in response to the frequency fluctuation of the sending end power grid crossing the control dead zone, start the rotor kinetic energy control and pitch angle control collaborative control, wherein: reduce the active power through the rotor kinetic energy control; At the same time, through the pitch angle control, increase the pitch angle at the maximum change rate; In the process of rotor kinetic energy control response and pitch angle control collaborative control, continuously monitor the frequency of the sending end power grid and the speed of the wind turbine, and lock the frequency deviation input of the pitch angle control;

[0041] Step 3, continuously monitor whether the frequency of the sending end power grid rises to the set maximum value and whether the pitch angle of the wind turbine rises to the set maximum value, if both are no, continue to increase the pitch angle at the maximum change rate, and lock the frequency deviation input of the pitch angle control;

[0042] Step 4, if the pitch angle reaches the set maximum value first, keep the maximum value unchanged, and control the wind turbine to run according to the maximum value of the pitch angle;

[0043] If the frequency of the sending end power grid reaches the set maximum value first, calculate the maximum frequency deviation at the maximum value of the frequency of the sending end power grid, and calculate the pitch angle size at the maximum frequency deviation combined with the target pitch angle algorithm, and take it as the first target value of the pitch angle control, control to increase the pitch angle to the first target value at the maximum change rate and keep it unchanged, and the wind turbine runs according to the first target value of the pitch angle;

[0044] Step 5, in the process of the rotor kinetic energy control responding to the pitch angle control, the rotor speed of the wind turbine is continuously monitored: if the rotor speed does not reach the preset value, the pitch angle control is executed according to the step 4; if the rotor speed reaches the preset value, the rotor kinetic energy control responding to the pitch angle control is exited;

[0045] Step 6, in response to the exit of the rotor kinetic energy control responding to the pitch angle control, a second target value of the pitch angle control under the real-time frequency deviation is calculated according to the target pitch angle algorithm, and the pitch angle is controlled to fall back to the second target value from the current value at the fastest change rate, and the frequency and the rotor speed are still continuously monitored during the pitch angle falling back, and the frequency deviation input of the pitch angle control is locked.

[0046] Step 7, in response to the pitch angle falling back to the second target value, the frequency deviation input of the pitch angle control is opened, so that the pitch angle size will change with the frequency deviation, and gradually transition to a stable value without changing, thereby completing the frequency control of the sending end power grid.

[0047] In the step 2, the dynamic change of the system frequency of the sending end power grid is characterized according to the change of the per-unit value of the inertia center speed of the sending end power grid, and the rotor kinetic energy control responding to the pitch angle control is started when the fluctuation of the per-unit value of the inertia center speed of the sending end power grid exceeds the preset control dead zone threshold range.

[0048] In the step 3, the rotor kinetic energy control (for example, the integrated control of the virtual inertia and the droop control) and the pitch angle control immediately respond, and only the frequency deviation input of the pitch angle control is locked, which aims to make the pitch angle not be affected by the frequency change and only increase at the maximum change rate, so as to quickly reduce the active power output of the wind turbine and effectively suppress the rise of the frequency.

[0049] As an optional embodiment, the rotor kinetic energy control includes introducing the frequency deviation and the frequency change rate of the sending end power grid into the active power control loop of the wind turbine to reduce the active power output of the wind turbine; through the rotor kinetic energy control, the rotor speed of the wind turbine is increased, so that the time for the rotor speed to drop to 0.85pu is lengthened, and the cooperative control time is prolonged.

[0050] In the embodiment of the application, in the step 4, the first target value β1 of the pitch angle is determined according to the target pitch angle algorithm when the frequency deviation reaches the maximum value. As an optional embodiment, the input quantity of the target pitch angle algorithm is the frequency deviation signal, which is amplified by different droop parameters to obtain an active power target value, and then based on the relationship between the active power target value and the pitch angle target value under different wind speeds (i.e. under a specific wind speed), the pitch angle target value is obtained.

[0051] In the step 5, the relationship between the active power target value and the pitch angle target value under different wind speeds is set to be obtained in the following manner:

[0052] Based on the simulation model of the wind turbine, the active power output data corresponding to different input wind speeds and different pitch angle sizes are obtained, and the active power output is taken as the independent variable, and the corresponding pitch angle is taken as the dependent variable, and the exponential function fitting is carried out by using the nonlinear least square method.

[0053] For example, the general expression of the fitting function is:

[0054]

[0055] That is, the specific pitch angle target value calculation formula under different wind speeds; wherein A and B represent coefficients respectively, P represents active power, β(P) represents the pitch angle corresponding to the active power P, k p is the attenuation coefficient of the exponential term.

[0056] Thus, the relationship between the active power and the corresponding pitch angle target value is obtained.

[0057] In combination with the embodiment shown in Figure 1 In step 5, considering that the general wind turbine is prone to increase the risk of failure (such as deterioration of power quality, damage to mechanical parts, etc.) when the speed is lower than 0.80p.u., it is necessary to set the exit control; at the same time, considering the influence of the damping and inertia of the rotor, a safety adjustment margin is needed, so the wind turbine speed of 0.85p.u. is set as the exit criterion, wherein p.u. represents the unit value.

[0058] In combination with Figure 1 In step 6, when the cooperative frequency modulation control is exited, the second target value of the pitch angle control needs to be calculated, and the specific method is: using the frequency deviation value at the exit as the input, calculating the second target value β2 of the pitch angle at this time according to the target pitch angle algorithm, and then the pitch angle falls back to the second target value β2 at the fastest change rate from the existing value.

[0059] In the embodiment of the application, in the pitch angle falling back section, the sending end power grid frequency and the wind turbine speed are still continuously monitored, and only the frequency deviation input of the pitch angle control is locked out, and the purpose is to quickly fall back the pitch angle, gradually slow down the speed decline trend, and recover the speed, so that the speed is quickly out of the alarm area.

[0060] In step 7, the pitch angle is opened only after reaching the target value β2, and the frequency deviation input of the pitch angle control is opened, and the subsequent stage pitch angle size control will change with the remaining frequency deviation, and the purpose is that the frequency fluctuation is no longer obvious at this time, and gradually returns to the stable value and no longer changes, so as to achieve the effect of smooth exit of the wind turbine from the frequency modulation control.

[0061] {Example 2}

[0062] In this embodiment, we combine Figure 1 the flow of the example shown to further illustrate the specific implementation of the present application.

[0063] In this embodiment, a four-machine two-area simulation system containing wind turbines is used for illustration. In combination with Figure 2 shown, the structure of the simulation system is a four-machine two-area simulation system, including two areas connected by two tie lines, each of which has two parallelly running synchronous generators, and the system load model uses constant impedance load, which is connected to bus 7 and bus 9 respectively, and is equipped with reactive power compensation capacitors. The rated active output of the four generators is 900 MW, and the transmission power of the tie line is 413 MW when the system is in steady state, which is transmitted from the left area to the right area. Figure 2

[0064] Therefore, the left area of the system shown in Figure 2 is defined as the sending-end power grid, and the right area is defined as the receiving-end power grid. 45 wind turbines with a rated power of 2 MW are connected to bus 6 in the sending-end power grid, with a total capacity of 90 MW. The disturbance is set to occur at bus 9 in the receiving-end power grid.

[0065] In combination with the system shown in Figure 2 , the inertial center speed of the sending-end power grid is calculated according to the rotor angular speed of the two synchronous generators in the sending-end power grid area, which is used to reflect the dynamic change process of the system frequency.

[0066] The following formula (1) is the calculation formula of the inertial center speed, where H1 and H2 are the inertia time constants of generator 1 and generator 2, and ω1 and ω2 represent the rotor angular speeds of generator 1 and generator 2 respectively.

[0067]

[0068] When the frequency disturbance of the sending-end power grid (i.e. the fluctuation amplitude of the sending-end power grid frequency from the preset frequency value) is detected to exceed the control dead zone (such as 0.03 Hz), the rotor kinetic energy control (the integrated control of virtual inertia and droop) responds immediately to reduce the active output, while the pitch angle control is started to respond cooperatively to increase the pitch angle at the maximum change rate β rate_max .

[0069] In this embodiment, a constant medium-high wind speed of 10 m / s is taken as an example for simulation, and the total simulation time is 200 s. At 80 s, a disturbance is set, and the load at bus 9 suddenly decreases from 1500 MW to 150 MW. Among them, the change rate range of the pitch angle of the wind turbine is [-5° / s, +5° / s], the maximum change rate β rate_max is set to 5° / s, and the pitch angle change range is set to [0°, 45°], corresponding to the maximum pitch angle β​max =45°.

[0070] Furthermore, the rotor kinetic energy control responds immediately, and the typical integrated control strategy structure is as follows Figure 3 As shown, in this example, K df =140,K pf =70, the reduced active power output is ΔP ref , the calculation method is shown in the following formula (2).

[0071] At the same time, the pitch angle control starts from 0° and changes at a rate of 5° / s (i.e. the aforementioned maximum change rate β rate_max =5° / s) to increase the pitch angle.

[0072]

[0073] During the coordinated control process of rotor kinetic energy control and pitch angle control, the frequency and pitch angle of the sending-end power grid are continuously monitored, and in the pitch angle control, the frequency deviation input of the pitch angle control is locked (that is, the frequency deviation input is not used as the input of the pitch angle adjustment control, but the maximum rate increase strategy is adopted).

[0074] During the collaborative control process, the frequency is continuously checked to see if it reaches the maximum value f. max , or whether the pitch angle reaches the set maximum value β max If the detection result is negative, the pitch angle continues to increase at the maximum rate of change.

[0075] (1) If the pitch angle of the wind turbine reaches the set maximum value first, the maximum value is maintained unchanged, and the wind turbine operates at the maximum pitch angle;

[0076] (2) If the frequency of the sending-end power grid reaches its maximum value first, the pitch angle at this maximum frequency deviation is calculated according to the target pitch angle algorithm and used as the first target value. The pitch angle remains unchanged after it is increased to this target value. Specifically:

[0077] When the frequency of the sending-end power grid reaches the set maximum value first, the maximum frequency deviation at the maximum frequency of the sending-end power grid is calculated, and the pitch angle at the maximum frequency deviation is calculated in combination with the target pitch angle algorithm, and is used as the first target value for pitch angle control. The pitch angle is controlled to increase at the maximum change rate to the first target value and then remain unchanged, and the wind turbine operates according to the first target value of the pitch angle.

[0078] Combine Figure 2The maximum value of the frequency is about 50.08 Hz, and the size of the pitch angle is about 17 degrees, which has not reached the maximum value, so the target value of the pitch angle is calculated according to the target pitch angle algorithm at this time.

[0079] As described above, the calculation method of the target pitch angle is as follows: based on the simulation model, the active power data corresponding to the wind turbine is obtained according to the specific input wind speed and different pitch angle sizes. For example, at a wind speed of 10 m / s, the data shown in Table 1 is obtained.

[0080] Table 1 Active power and pitch angle values at a wind speed of 10 m / s

[0081] P (p.u.) 0.707 0.673 0.633 0.608 0.591 β (deg) 0.5 1.0 1.5 2.0 2.5 P (p.u.) 0.578 0.564 0.549 0.540 0.527 β (deg) 3.0 3.5 4.0 4.5 5.0

[0082] The data in Table 1 is fitted with an exponential function (a first-order model is used in this example), and the function image is obtained as shown in Figure 4 The confidence boundary is 95%, and the fitting formula is:

[0083] β=2328e -11.59P (3)

[0084] Further, the input of the target pitch angle algorithm is the frequency deviation signal, which is amplified by the different droop parameters K p (500) of the rotor kinetic energy control to obtain the active power target value. The quantitative relationship between the active power target value and the pitch angle is formula (3), and the specific control block diagram is shown in Figure 5 .

[0085] When the frequency deviation reaches the maximum value Δf max ≈0.08 Hz (calculated using the unit value 0.0016 p.u., and the reference value is the rated frequency 50 Hz), the first target value of the pitch angle is calculated by formula (4) as β1≈22.5°:

[0086] The specific calculation steps of β1are as follows:

[0087]

[0088] At this time, the maximum value β max =45° has not been reached, and the pitch angle can approach the target value at the maximum rate β rate_max =5° / s.

[0089] Further, the rotor speed is continuously monitored and compared with the 0.85 p.u. of the exit cooperative control. If it reaches 0.85 p.u., the cooperative control is exited, otherwise the size of the pitch angle is maintained.

[0090] In the embodiment, as aforementioned, the criterion of reaching 0.85 p.u. for the rotational speed is set as the criterion of exiting the cooperative control.

[0091] As aforementioned, after reaching the condition of exiting the cooperative control, the second target value of the pitch angle control at the frequency deviation is calculated according to the target pitch angle algorithm. The pitch angle falls back to the new target value from the existing value at the fastest change rate, and during the period, the frequency and the rotational speed are still continuously detected, but the frequency deviation input of the pitch angle control is blocked.

[0092] Further, the second target value of the pitch angle is about 0.055 Hz for the frequency deviation Δf at this time (calculated by using the unit 0.0011 p.u.), and the corresponding pitch angle value β2≈4° is still calculated by using the fitting function formula (3), and the specific calculation steps are as follows:

[0093]

[0094] Further, after the pitch angle falls back to the second target value 4°, the frequency deviation input of the pitch angle control is opened, and the subsequent pitch angle value will change with the remaining frequency deviation, and gradually transitions to the stable value about 6° and no longer changes.

[0095] According to the process of the above embodiment, it can be observed that Figure 6 and Figure 9 It can be observed that the single rotor kinetic energy control has a fast response speed, but the frequency regulation effect is mainly reflected in the frequency rising stage, although the frequency rising is obviously slowed down and the highest frequency point is lowered, but the improvement of the steady-state frequency is not obvious; the single target pitch angle control has a large adjustable range, but the response speed is slower than the rotor kinetic energy control due to the limitation of the mechanical action rate, and the single pitch angle control will cause the rotational speed of the wind turbine to be significantly reduced, which is not conducive to the stable operation of the unit.

[0096] As shown in Figure 7 , the wind turbine target pitch angle cooperative control method proposed by the application combines the two, which effectively plays the role of the large adjustable range of the pitch angle control on the active power output, and simultaneously effectively improves the rotational speed of the unit by using the rotor kinetic energy control. Figure 8 and Figure 9 It can be seen that when the cooperative control method is used, the action time of the pitch angle control is obviously prolonged, and the highest frequency point and the steady-state frequency value are effectively reduced.

[0097] Further, as shown in Figures 10-12 , compared with the traditional pitch angle frequency droop control, the wind turbine target pitch angle cooperative control method according to the aforementioned embodiment of the application has obvious improvement in the cooperative control effect by the cooperative response control of the pitch angle and the rotor kinetic energy based on the target value of the pitch angle change. As Figures 10 to 12The active power, the speed of the wind turbine and the variation of the system frequency under the targetless pitch angle cooperative control and the target pitch angle cooperative control of the present application are compared as follows: Figure 11 It can be seen from the above that, under the targetless pitch angle cooperative control, the speed will be higher than the steady state value before the frequency modulation, the maximum value of the frequency can be reduced, but the amplitude is relatively small, and the steady state value of the frequency after the fault is not significantly improved.

[0098] {Example 3}

[0099] In combination with the implementation of the wind turbine target pitch angle cooperative control method of the above embodiments, according to the present application, a computer system is further proposed, comprising:

[0100] one or more processors; and

[0101] a memory storing instructions operable.

[0102] The instructions, when executed by the one or more processors, cause the aforementioned one or more processors to perform operations, the operations comprising executing the process of the wind turbine target pitch angle cooperative control method of the aforementioned embodiments.

[0103] In combination with the implementation of the wind turbine target pitch angle cooperative control method of the above embodiments, according to the present application, a computer readable storage medium is further proposed for storing one or more programs, the one or more programs comprising instructions or instruction sets executable by one or more processors.

[0104] The instructions or instruction sets, when executed by the one or more processors, execute the process of the wind turbine target pitch angle cooperative control method of the aforementioned embodiments.

[0105] Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Those skilled in the art without departing from the spirit and scope of the present application can make various modifications and improvements. Therefore, the protection scope of the present application shall be subject to the scope defined by the claims.

Claims

1. A wind turbine target pitch angle coordinated control method for high-frequency problems in the power grid at the sending end, characterized in that: The following steps are involved: Step 1: Continuously monitor the frequency and frequency fluctuation of the sending-end power grid; Step 2: In response to the frequency fluctuation of the sending-end power grid exceeding the control dead zone, the coordinated control of the rotor kinetic energy control and the pitch angle control is initiated, wherein: the active power output is reduced through the rotor kinetic energy control; and the pitch angle is increased at a maximum rate of change through the pitch angle control; during the coordinated control process of the rotor kinetic energy control response and the pitch angle control, the frequency of the sending-end power grid and the speed of the wind turbine are continuously monitored, and the frequency deviation input of the pitch angle control is locked; Step 3: continuously monitoring whether the frequency of the power grid at the sending end has reached a set maximum value, and whether the pitch angle of the wind turbine has reached a set maximum value; if both are negative, then continuing to increase the pitch angle at the maximum rate of change, and blocking the frequency deviation input of the pitch angle control; Step 4: If the pitch angle reaches the set maximum value first, the maximum value is maintained unchanged, and the wind turbine is controlled to operate according to the maximum value of the pitch angle; If the frequency of the sending-end power grid reaches the set maximum value first, the maximum frequency deviation at the maximum frequency of the sending-end power grid is calculated, and the pitch angle at the maximum frequency deviation is calculated in combination with the target pitch angle algorithm, and the pitch angle is used as the first target value of the pitch angle control. The pitch angle is controlled to increase at the maximum change rate to the first target value and then remain unchanged. The wind turbine operates according to the first target value of the pitch angle; Step 5: During the coordinated control of the rotor kinetic energy control response and the pitch angle control, the speed of the wind turbine is continuously monitored. When the speed decreases but does not reach a preset value, the pitch angle control is performed according to Step 4. If the speed decreases and reaches a preset value, the coordinated control of the rotor kinetic energy control and the pitch angle control is exited. Step 6: In response to exiting the coordinated control of rotor kinetic energy control and pitch angle control, the second target value of the pitch angle control under the real-time frequency deviation is calculated according to the target pitch angle algorithm, and the pitch angle is controlled to fall from the current value to the second target value at the fastest rate of change. During the period of pitch angle fall, the frequency and speed are still monitored, and the frequency deviation input of the pitch angle control is locked. Step 7: In response to the pitch angle falling back to the second target value, the frequency deviation input of the pitch angle control is opened, so that the pitch angle changes with the frequency deviation, gradually transitions to a stable value and no longer changes, thereby completing the frequency regulation control of the sending-end power grid.

2. The method for coordinated target pitch angle control of wind turbines for high-frequency problems of the power grid at the sending end according to claim 1 is characterized in that: In step 2, the dynamic change of the sending-end power grid system frequency is characterized according to the change of the per-unit value of the inertia center speed of the sending-end power grid, and when the fluctuation of the per-unit value of the inertia center speed of the sending-end power grid exceeds a preset control dead zone threshold range, the rotor kinetic energy control and the pitch angle control are started in coordination.

3. The method for coordinated target pitch angle control of wind turbines for high-frequency problems of the power grid at the sending end according to claim 1 is characterized in that: In step 2, the rotor kinetic energy control includes: The frequency deviation and frequency change rate of the sending-end power grid are introduced into the active power control loop of the wind turbine to reduce the active output of the wind turbine.

4. The method for coordinated target pitch angle control of wind turbines for high-frequency problems of the power grid at the sending end according to claim 3 is characterized in that: By controlling the rotor kinetic energy, the speed of the wind turbine is increased, which prolongs the time it takes for the speed to drop to 0.85pu and extends the coordinated control time.

5. The method for coordinated target pitch angle control of wind turbines for high-frequency problems of the power grid at the sending end according to any one of claims 1 to 4, characterized in that: The input of the target pitch angle algorithm is the frequency deviation signal, which is amplified by a droop parameter different from the rotor kinetic energy control to obtain the active power target value. Then, based on the relationship between the active power target value and the pitch angle target value at different wind speeds, the pitch angle target value is obtained.

6. The method for coordinated target pitch angle control of wind turbines for high-frequency problems of the power grid at the sending end according to claim 5, characterized in that: The relationship between the active power target value and the pitch angle target value at different wind speeds is set to be obtained in the following manner: Based on the simulation model of the wind turbine, the active output data of the corresponding wind turbine is obtained according to different input wind speeds and different pitch angles. The active output is used as the independent variable and the corresponding pitch angle is used as the dependent variable. The exponential function is fitted using the nonlinear least squares method to obtain the relationship between the active output and the corresponding pitch angle target value.

7. The method for target-based coordinated pitch angle control of wind turbines for high-frequency problems in the power grid at the sending end according to claim 1, characterized in that: In step 5, the criterion for determining whether to exit the coordinated control when the speed of the wind turbine generator set decreases is set to 0.85 pu, where pu represents per-unit value.

8. A computer system, characterized in that: include: one or more processors; as well as Memory, which stores instructions that can be operated; Wherein, when the instruction is executed by one or more processors, the one or more processors mentioned above perform an operation, and the operation includes the process of executing the wind turbine target pitch angle coordinated control method as described in any one of claims 1-7.

9. A computer-readable storage medium for storing one or more programs, characterized in that: The one or more programs include instructions or sets of instructions that can be executed by one or more processors; Wherein, when the instruction or instruction set is executed by one or more processors, the process of the wind turbine target pitch angle coordinated control method according to any one of claims 1 to 7 is executed.

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