A reactive voltage control method and device for large-scale wind farms considering voltage regulation margin

Abstract

The application discloses a large-scale wind farm reactive power voltage control method and device considering voltage regulation margin, and the method comprises the following steps: firstly, the reactive power setting layer calculates the reactive power compensation demand value of the wind farm; secondly, the reactive power distribution layer considers the voltage regulation margin of the reactive power compensation device and the wind turbine generator, and selects the corresponding reactive power compensation method according to the voltage regulation margin; the reactive power compensation device configured in the wind farm is preferentially selected for reactive power regulation, if the compensation device cannot meet the voltage stability requirement, the reactive power compensation value is distributed according to the reactive power capacity proportion algorithm according to the operation state of each wind turbine generator; the grid-side converter of the wind turbine generator adopts adaptive droop control to realize maximum reactive power capacity compensation, if the reactive power shortage still exists, the wind turbine generator needs to be controlled to reduce load to realize reactive power support for the power grid voltage; finally, the wind farm coordinates the wind turbine generator and the reactive power compensation device to provide sufficient reactive power support, so that the grid connection point voltage remains stable.

Description

TECHNICAL FIELD

[0001] The application relates to a large wind farm reactive voltage control method and device considering voltage regulation margin, and belongs to the technical field of power system automation. BACKGROUND

[0002] New energy will replace traditional energy and be widely used in power systems. Renewable energy represented by wind power has developed rapidly, however, large-scale wind power integration has brought adverse effects on the safe and stable operation of the system, mainly in voltage, frequency, subsynchronous oscillation and other aspects. Wind farms in China generally use centralized control. When the wind farm is affected by wind speed fluctuations, the line reactive power loss increases, there is a risk of exceeding the grid voltage, and thus the safety and stability of the power system are affected. In recent years, there have been several large-scale wind turbine cascading tripping accidents in China, which are closely related to the reactive power and voltage control of wind farms. At present, the research at home and abroad on improving the reactive power level of wind farms and the voltage quality of the grid connection point mainly proceeds in two aspects: configuring reactive power compensation devices in the system to ensure the voltage stability of the wind farm, or starting from the wind farm itself, developing a wind farm reactive control scheme.

[0003] The mainstream doubly fed induction generator (DFIG) and permanent magnet synchronous generator (PMSG) can both participate in grid dynamic reactive power control by utilizing their own reactive power regulation capabilities. When the grid drops slightly, local compensation can be performed by relying on the reactive power compensation of the wind turbine itself. Permanent magnet direct drive wind turbines have better reactive voltage characteristics than doubly fed wind turbines, and utilizing the reactive power regulation capability of permanent magnet direct drive wind turbines to provide reactive power support for the system has become an important means of reactive voltage control. When the system voltage decreases, the grid-side converter of the permanent magnet direct drive wind turbine controls the active and reactive power decoupling, and can quickly provide certain reactive power support to the grid through adjustment. In addition, the future time period can be predicted based on the active power prediction value, and the reactive power output between wind farm units can be distributed in advance to improve the control speed and ensure the stability of the grid connection point voltage.

[0004] The existing research method rarely analyzes the reactive power output characteristics of wind farms in combination with the regulation capability of wind turbines and reactive power compensation devices, and therefore an optimal control strategy is needed to adjust the reactive power compensation method according to the operating state of the wind farm. SUMMARY

[0005] The present application aims to overcome the deficiencies in the prior art, and provide a large wind farm reactive power voltage control method and device considering voltage regulation margin, to solve the problem that the prior art does not adjust the compensation method according to the system voltage regulation margin.

[0006] To achieve the above-mentioned purpose, the present application is implemented by using the following technical solutions:

[0007] In the first aspect, the present application provides a large wind farm reactive power voltage control method and device considering voltage regulation margin, including a wind farm, wherein a reactive power compensation device and a wind turbine generator are configured in the wind farm, the method is applied to the wind farm, and includes the following steps:

[0008] In the voltage mode, the total reactive power demand value of the entire wind farm is calculated;

[0009] It is judged whether the reactive power compensation demand is met, when the reactive power compensation demand is met, the reactive power is adjusted by the reactive power compensation device, and if the reactive power compensation device cannot meet the reactive power compensation amount, the reactive power compensation is performed by using the wind turbine generator;

[0010] It is judged whether the reactive power capacity of the wind turbine generator is sufficient, when the reactive power capacity of the wind turbine generator is sufficient, the wind turbine generator operates in an adaptive droop control mode, and when the reactive power capacity of the wind turbine generator is insufficient, the wind turbine generator operates in a load shedding control mode.

[0011] Further, when the wind turbine generator operates in the adaptive droop control mode, the wind turbine generator grid-side converter sets an adaptive droop coefficient, the droop coefficient is automatically adjusted with the change of wind speed, and the reactive power output of each unit is reasonably distributed to support the grid point voltage.

[0012] Further, when the wind turbine generator operates in the load shedding control mode, a corresponding load shedding method is adopted according to the change of wind speed, the rotor speed is adjusted, and the load shedding is realized by combining the pitch angle control to increase the reactive power output, and the grid-side converter remains in the adaptive droop control.

[0013] Further, it further includes receiving the reactive power instruction issued by the upper level as the total reactive power demand value of the wind farm.

[0014] Further, in the voltage mode, the total reactive power demand value of the entire wind farm is calculated, including:

[0015] The grid point voltage is taken as a control object, the grid point reference voltage U ref is compared with the actual operating voltage U cur , the deviation voltage ΔU is obtained, the total reactive power demand Q ref of the entire wind farm is obtained by using a proportional integral controller, and the formula is as follows:

[0016] Q ref =K P (Uref -U cur )+K I ∫(U ref -U cur )dt (1)

[0017] In the formula: K P K I These are the proportional-integral coefficients, K P Set to U cur The ratio of the reactance of the transmission line between the grid connection point and the wind farm busbar; K I Adjustments were made based on experience.

[0018] Furthermore, when the wind turbine is operating in adaptive droop control mode, the reactive current output of the adaptive droop control loop is defined as:

[0019]

[0020]

[0021] In the formula: V sys V is the effective value of the voltage. nom This is the rated voltage value. The adaptive droop factor is proportional to the reactive power of the wind turbine, Q. W,i Let be the reactive power of wind turbine unit i; C is a constant coefficient.

[0022] Furthermore, the control method for the wind turbine operating in the load reduction control mode is as follows:

[0023] Determine the minimum reactive power Q supplied to the grid connection point while ensuring stable grid voltage. L Because the output power of the wind turbine meets Furthermore, the closer a wind turbine is to its rated state, the greater the reactive power released by the same power reduction. Therefore, it is necessary to determine the load reduction priority of each unit and select wind turbines for load reduction control.

[0024] Furthermore, the wind turbine operates in a load shedding control mode, which is divided into three wind speed ranges: low, medium, and high, and employs different load shedding control methods in each range, including:

[0025] In the low wind speed range, the wind turbine operates in maximum power point tracking mode, at which point the wind energy capture factor reaches its maximum C. pmax When the blade pitch angle β is 0°, and a load reduction of d% is required, C is calculated based on the tip speed ratio-wind energy capture coefficient curve. pmax The tip velocity ratio λ corresponding to a decrease of d% d1 Then, the reference rotor speed ω after load reduction can be obtained. d1 ;

[0026] In the high wind speed interval, the wind turbine is also in the maximum power tracking operation state, and the rotor is in the optimal speed ω opt , the corresponding active power is P opt When the load needs to be reduced by d%, if the rotor speed reaches the maximum allowable speed ω max during the overspeed load reduction process, the load reduction needs to be realized in cooperation with the pitch angle control, and the reference power setting of the variable pitch control is:

[0027]

[0028] In the high wind speed interval, when v W2 <v W <v Wn , the wind turbine is in the constant speed operation mode, when the load needs to be reduced by d%, the wind energy capture coefficient C pd after load reduction is calculated, and the Newton method is used to solve the pitch angle β d for adjustment, when v Wn <v W <v W_out , the wind turbine is in the constant power operation mode, and the output power of the wind turbine is the rated power P n , when the load needs to be reduced by d%, the reference power is only set to (1-d%) P n .

[0029] In a second aspect, the present application provides a large-scale wind farm reactive voltage control device considering voltage regulation margin, comprising a wind farm, wherein a reactive compensation device and a wind turbine are arranged in the wind farm, the device is applied to the wind farm, and comprises:

[0030] A calculation unit is configured to calculate the total reactive demand value of the entire wind farm in the voltage mode.

[0031] A first judgment unit is configured to judge whether the reactive compensation demand is met, and when the reactive compensation demand is met, the reactive power is adjusted by the reactive compensation device, and when the reactive compensation device cannot meet the reactive compensation amount, the reactive compensation is realized by the wind turbine.

[0032] A second judgment unit is configured to judge whether the reactive capacity of the wind turbine is sufficient, and when the reactive capacity of the wind turbine is sufficient, the wind turbine operates in the adaptive droop control mode, and when the reactive capacity of the wind turbine is insufficient, the wind turbine operates in the load reduction control mode.

[0033] In a third aspect, the present application provides a computer readable storage medium, which stores a computer program, and the program is executed by a processor to realize the steps of the method of any one of the above aspects.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] The application provides a reactive voltage control method and device for large-scale wind farms considering voltage regulation margin, which preferentially selects reactive compensation devices configured in the wind farm to perform reactive regulation, and if the compensation devices cannot meet the voltage stability requirement, the reactive compensation value is distributed according to the reactive capacity proportion algorithm according to the operation state of each wind turbine generator, the grid-side converter of the wind turbine generator adopts adaptive droop control to realize maximum reactive capacity compensation, if the reactive deficiency still exists, the wind turbine generator needs to be controlled to reduce load to realize reactive support for the grid voltage, finally, the wind farm coordinates the wind turbine generator and the reactive compensation device to provide sufficient reactive support, so that the grid connection point voltage remains stable, and the problem that the compensation method is not adjusted according to the system voltage regulation margin in the prior art is solved. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a reactive voltage control flowchart provided by the embodiment of the application;

[0037] Figure 2 is a wind farm reactive voltage hierarchical control structure schematic diagram provided by the embodiment of the application;

[0038] Figure 3 is a wind farm reactive setting link schematic diagram provided by the embodiment of the application;

[0039] Figure 4 is a reactive power distribution flowchart provided by the embodiment of the application;

[0040] Figure 5 is an adaptive droop control link schematic diagram provided by the embodiment of the application;

[0041] Figure 6 is a wind turbine generator load reduction control curve schematic diagram provided by the embodiment of the application. DETAILED DESCRIPTION

[0042] The application will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the application, and cannot be used to limit the protection scope of the application.

[0043] Embodiment 1

[0044] This embodiment introduces a reactive voltage control method for large-scale wind farms considering voltage regulation margin, which comprises a wind farm, the wind farm is configured with reactive compensation devices and wind turbine generators, and the method is applied to the wind farm and comprises the following steps.

[0045] In the voltage mode, the total reactive demand value of the entire wind farm is calculated;

[0046] judging whether the reactive power compensation demand is met, when the reactive power compensation demand is met, the reactive power is adjusted by the reactive power compensation device, if the reactive power compensation device cannot meet the reactive power compensation amount, the wind turbine is used for reactive power compensation;

[0047] judging whether the reactive power capacity of the wind turbine is sufficient, when the reactive power capacity of the wind turbine is sufficient, the wind turbine operates in an adaptive droop control mode, when the reactive power capacity of the wind turbine is insufficient, the wind turbine operates in a load shedding control mode.

[0048] The method for reactive power and voltage control of large-scale wind farms considering voltage regulation margin provided by the embodiment specifically comprises the following steps in the application process:

[0049] Step 1, a hierarchical control composed of a wind farm reactive power setting layer and a wind turbine reactive power distribution layer is established, wherein the reactive power setting layer determines the reactive power reference value of the wind farm output to the grid point, the wind turbine reactive power distribution layer distributes the compensation amount considering the system voltage regulation margin, and a wind turbine grid operation model of large-scale wind farms is established;

[0050] Step 2, the wind farm reactive power setting layer takes the grid point voltage as the control object, the wind farm can set the reactive power in the constant voltage mode according to the system set voltage, the reference voltage of the grid point is subtracted from the actual operating voltage, the deviation voltage is obtained, and the proportional integral controller is used to obtain the total reactive power demand of the entire wind farm, or the wind farm reactive power demand value can be received as the upper-level reactive power instruction.

[0051] Step 3, the wind turbine reactive power distribution layer distributes the reactive power compensation amount calculated in step 2 to the wind turbine and the reactive power compensation device according to the wind farm operating state, considering the system voltage regulation margin and the proportion of reactive power capacity. First, the SVC is used for reactive power compensation, and if the SVC cannot meet the reactive power compensation amount, the wind turbine is used for reactive power compensation.

[0052] Step 4, the wind farm reactive power adjustable capacity is judged, if the wind turbine adjustable capacity meets the reactive power compensation amount, step 5 is executed, and the grid-side converter of the wind turbine adopts adaptive droop control. If the wind turbine adjustable capacity cannot completely meet the system reactive power adjustment requirement, step 6 is executed, and part of the wind turbine needs to be controlled in load shedding mode.

[0053] Step 5, the wind turbine adopts adaptive droop control, the adaptive droop coefficient is set in the reactive power control link of the grid-side converter, which can automatically adjust with the change of wind speed, reasonably distribute the reactive power output of each unit to support the grid point voltage and ensure the stable operation of the system;

[0054] Step 6, the wind turbine adopts load shedding operation mode, corresponding load shedding methods are adopted according to the change of wind speed, the rotor speed is adjusted and combined with the pitch angle control to realize load shedding, the reactive power output is increased, and the grid-side converter maintains adaptive droop control.

[0055] In step 1, the wind farm reactive voltage hierarchical control structure is as shown in Figure 2 The wind farm hierarchical control first carries out wind farm reactive demand setting: if the reactive reference value obtained by setting is greater than the wind farm reactive output value, it indicates that there is a reactive output shortage. Since the static var compensator has the advantage of fast dynamic response speed, the SVC is first used when adjusting the reactive power, and if the SVC cannot meet the reactive compensation amount, the wind farm reactive adjustable capacity needs to be judged. If the wind turbine generator adjustable capacity meets the reactive compensation amount, the wind turbine generator grid-side converter uses adaptive droop control to adjust the output power according to the compensation amount allocated to each unit to provide reactive support. If the wind turbine generator adjustable capacity cannot completely meet the system reactive adjustment requirement, some wind turbine generators need to be controlled to reduce load to increase the maximum reactive capacity of the unit and provide sufficient reactive support for the grid connection point

[0056] In step 3, the wind farm reactive demand setting link is used to determine the reactive power reference value of the wind farm output to the grid connection point. The wind farm can set the reactive power according to the system set voltage in the constant voltage mode, or receive the reactive instruction from the upper level as the wind farm reactive demand value.

[0057] If there is a wind farm reactive instruction value arranged by the upper level dispatching, it is issued to the wind farm, and set Q ref = Q set If the constant voltage mode is selected, the grid connection point voltage is taken as the control object, the grid connection point reference voltage U ref is compared with the actual operating voltage U cur , the deviation voltage ΔU is obtained, and the proportional integral controller is used to obtain the total reactive demand Q ref of the entire wind farm, and the specific process is as shown in Figure 3

[0058] The wind farm reactive reference value is:

[0059] Q ref = K P (U ref -U cur )+K I ∫(U ref -U cur )dt (1)

[0060] In the formula, K P and K I are proportional integral coefficients, K P is set as the ratio of U cur and the reactance of the transmission line between the grid connection point and the wind farm bus; and K I is adjusted according to experience.

[0061] ​In step 4, the allocation principle of the reactive power allocation layer of the wind turbine is shown in Figure 4 , which first considers the voltage regulation margin of the system to select the mode of reactive power compensation. Then, according to the compensation capacity of the SVC and the reactive power capacity of the wind turbine, the compensation amount determined by the setting layer is allocated to the SVC and the wind turbine. Finally, the wind turbine converter output reactive power is controlled according to the allocation value.

[0062] Q comp is the required reactive power compensation amount of the wind power system, ava is the available reactive power compensation amount of the wind power system. The speed of reactive power regulation of the permanent magnet direct drive wind turbine is fast, but the communication between the wind turbine and the control system will slow down the reactive power regulation speed of the unit. Therefore, when the reactive power capacity is greater than the compensation amount, the wind farm reactive power compensation device SVC is preferred, which can provide millisecond-level reactive power compensation to the grid connection point.

[0063] The required reactive power compensation amount Q comp of the wind farm is:

[0064] Q comp = Q ref - Q out

[0065] The adjustable amount of reactive power of the SVC and the wind turbine is calculated:

[0066] Q SVCava = Q SVCmax - Q SVCout

[0067] Q Wiava = Q Wimax - Q Wiout

[0068] In the formula, Q SVCava , Q SVCmax , Q SVCout are the adjustable capacity, the maximum reactive power compensation amount, and the current reactive power output of the SVC, respectively; Q Wiava , Q Wimax , Q Wiout are the adjustable capacity, the maximum reactive power compensation amount, and the current reactive power output of the i-th wind turbine, respectively.

[0069] If the SVC alone is used to provide reactive power compensation, its capacity cannot meet the system reactive power demand, i.e. Q SVCmax < Q comp , the wind turbine needs to be added for coordinated control, and the reactive power compensation amount of the wind turbine can be allocated according to the proportion of the reactive power capacity of each unit. The reactive power compensation distribution coefficient k i of the wind turbine is:

[0070]

[0071] In the formula: Q Wi is the reactive power capacity of the i th wind turbine, and n is the number of wind turbines in the wind farm.

[0072] The reactive power compensation amount of the wind farm is Q Wcomp , the reactive power compensation Q Wicomp allocated to the i th wind turbine is:

[0073] Q Wicomp = (Q comp - Q SVCava )k i

[0074] The reactive power capacity of the wind turbine is determined by the active power and the apparent power of the wind turbine. First, it is determined whether the allocated reactive power compensation of the wind turbine is greater than its reactive power capacity. When there is a lack of reactive power regulation margin of the wind turbine, the allocation scheme needs to be adjusted. Let the number of wind turbines with a lack of reactive power regulation margin be m, wherein the reactive power capacity Q j ’ of the j th wind turbine is:

[0075] Q Wjcomp ' = Q Wjcomp - Q Wj

[0076] The adjusted reactive power compensation amount allocation coefficient k j ’ of the j th wind turbine is:

[0077]

[0078] The allocation coefficient of other wind turbines is adjusted to k i ’, and the reactive power compensation amount is Q Wicomp ’:

[0079]

[0080] Q Wicomp ' = Q Wicomp k i '

[0081] When the reactive power capacity is less than the compensation amount, the wind turbine needs to be controlled by load shedding while being compensated by the SVC, so as to improve the reactive power capacity of the wind turbine by reducing part of the active output to support the grid point voltage.

[0082] In step 5, the grid-side converter in the converter adopts adaptive droop control, and the setting principle of the droop coefficient is based on the current reactive power capacity of the wind turbine. The adaptive droop link is as shown in Figure 5 The reactive current output of the adaptive droop control link is defined as:

[0083]

[0084]

[0085] In the formula: V sys V is the effective value of the voltage. nom This is the rated voltage value. The adaptive droop factor is proportional to the reactive power of the wind turbine, Q. W,i Let be the reactive power of wind turbine unit i; C is a constant coefficient.

[0086] The adaptive droop factor is a variable related to space and time. The droop factor can be adaptively adjusted with changes in wind speed, controlling the wind turbine to provide reactive power support according to its reactive power capacity. In addition, adaptive droop control avoids the wind turbine from frequently reaching the maximum reactive power limit, which helps to reduce the wear of the converter.

[0087] In step 6, the method for controlling the unloaded operation mode is as follows:

[0088] Determine the minimum reactive power Q that needs to be supplied to the grid connection point while ensuring grid voltage stability. L Because the output power of the wind turbine meets Furthermore, the closer the wind turbine is to its rated state, the greater the reactive power released by the same power reduction. Therefore, it is necessary to determine the load reduction priority of each unit and select the wind turbine for load reduction control.

[0089]

[0090] In the formula: S is the rated power of the wind turbine; ΔP is the active power output of wind turbine unit i; ΔP is the load reduction; ΔQ w,i is the reactive power increment after the i-th wind turbine is unloaded, k is the number of the wind turbine that is unloaded, and j is the number of wind turbines that are unloaded.

[0091] The load reduction level d% can be expressed as d% = ΔP W,i / P W,i .

[0092] The method for controlling the reduced-load operation mode is as follows: Based on wind speed, the system is divided into three wind speed ranges: low, medium, and high, and different reduced-load control methods are used in each range. Figure 6 As shown. In the low wind speed range, the wind turbine operates in maximum power point tracking mode, at which point the wind energy capture coefficient reaches its maximum C. pmax When the blade pitch angle β is 0°, and a load reduction of d% is required, C is calculated based on the tip speed ratio-wind energy capture coefficient curve. pmax The tip velocity ratio λ corresponding to a decrease of d% d1, and then the reduced rotor reference speed ω d1 ;

[0093] In the high wind speed interval, the wind turbine is also in the maximum power tracking operation state, and the rotor is in the optimal speed ω opt , and the corresponding active power is P opt When the load needs to be reduced by d%, if the rotor speed reaches the maximum allowable speed ω max during the overspeed reduction process, the load needs to be reduced in cooperation with the pitch angle control, and the reference power setting of the variable pitch control is:

[0094]

[0095] In the high wind speed interval, when v W2 <v W <v Wn , the wind turbine is in the constant speed operation mode, and when the load needs to be reduced by d%, the wind energy capture coefficient C pd after the load reduction is calculated, and the Newton method is used to solve the pitch angle β d for adjustment, when v Wn <v W <v W_out , the wind turbine is in the constant power operation mode, and the output power of the wind turbine is the rated power P n , and when the load needs to be reduced by d%, the reference power only needs to be set to (1-d%) P n .

[0096] Embodiment 2

[0097] The embodiment provides a large-scale wind farm reactive voltage control device considering voltage regulation margin, comprising a wind farm, wherein a reactive compensation device and a wind turbine are arranged in the wind farm, the device is applied to the wind farm, and comprises:

[0098] A calculation unit is configured to calculate a total reactive demand value of the entire wind farm in a voltage mode.

[0099] A first judgment unit is configured to judge whether a reactive compensation demand is met, and when the reactive compensation demand is met, the reactive compensation device is used for reactive adjustment, and when the reactive compensation device cannot meet the reactive compensation amount, the wind turbine is used for reactive compensation.

[0100] A second judgment unit is configured to judge whether a reactive capacity of the wind turbine is sufficient, and when the reactive capacity of the wind turbine is sufficient, the wind turbine operates in an adaptive droop control mode, and when the reactive capacity of the wind turbine is insufficient, the wind turbine operates in a load reduction control mode.

[0101] Embodiment 3

[0102] The embodiment provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement steps of the method in any one of the embodiments 1.

[0103] The above merely describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present application, and these improvements and modifications should also be considered as falling within the protection scope of the present application.

Claims

1. A reactive power and voltage control method for large-scale wind farms considering voltage regulation margin, characterized in that, The method, applied to a wind farm equipped with a reactive power compensation device and wind turbine generators, includes: Calculate the total reactive power demand of the entire wind farm in voltage mode; Determine whether the reactive power compensation requirement is met. If the reactive power compensation requirement is met, adjust the reactive power through the reactive power compensation device. If the reactive power compensation device cannot meet the reactive power compensation amount, use the wind turbine to perform reactive power compensation. To determine whether the reactive power capacity of the wind turbine is sufficient, when the reactive power capacity of the wind turbine is sufficient, the wind turbine operates in adaptive droop control mode; when the reactive power capacity of the wind turbine is insufficient, the wind turbine operates in load reduction control mode. When the wind turbine is operating in adaptive droop control mode, the reactive current output of the adaptive droop control loop is defined as follows: In the formula: V sys V is the effective value of the voltage. nom This is the rated voltage value. Q is the adaptive droop factor for wind turbine i, which is proportional to the reactive power of the wind turbine. W,i represents the reactive power of wind turbine unit i; C is a constant coefficient. The wind turbine operates in a load shedding control mode, which is divided into three wind speed ranges: low, medium, and high. Different load shedding control methods are used in each range, including: In the low wind speed range, the wind turbine operates in maximum power point tracking mode, at which point the wind energy capture factor reaches its maximum C. pmax When the blade pitch angle β is 0°, and a load reduction of d% is required, C is calculated based on the tip speed ratio-wind energy capture coefficient curve. pmax The tip velocity ratio λ corresponding to a decrease of d% d1 Then, the reference rotor speed ω after load reduction can be obtained. d1 ; In the medium wind speed range, the wind turbine also operates in maximum power point tracking mode, with the rotor at its optimal speed ω. opt The corresponding active power is P opt When a load reduction of d% is required, if the rotor speed reaches the maximum permissible speed ω during the overspeed load reduction process... max Then, pitch angle control is needed to achieve load reduction. The reference power setting for pitch control is: Within the high wind speed range, when v W2 <v W <v Wn When the wind turbine is operating at a constant speed and requires a load reduction of d%, calculate the wind energy capture factor C after the load reduction. pd And Newton's method is used to solve for the propeller pitch angle β. d Adjustment is made when v Wn <v W <v W_out At this time, the wind turbine is in constant power operation mode, and the output power of the wind turbine is the rated power P. n When a load reduction of d% is required, simply set the reference power to (1-d%)P. n That's all.

2. The reactive power and voltage control method for large wind farms considering voltage regulation margin according to claim 1, characterized in that: When the wind turbine is operating in adaptive droop control mode, the grid-side converter of the wind turbine is set with an adaptive droop coefficient. The droop coefficient is automatically adjusted according to the change of wind speed, so as to reasonably allocate the reactive power output of each unit to support the grid connection point voltage.

3. The reactive power and voltage control method for large wind farms considering voltage regulation margin according to claim 1, characterized in that: When the wind turbine is operating in load reduction control mode, it adopts a corresponding load reduction method according to the wind speed change, adjusts the rotor speed and combines it with pitch angle control to achieve load reduction, increase reactive power output, and the grid-side converter maintains adaptive droop control.

4. The reactive power and voltage control method for large wind farms considering voltage regulation margin according to claim 1, characterized in that: It also includes receiving reactive power instructions from higher authorities as the total reactive power demand value for the wind farm.

5. The reactive power and voltage control method for large wind farms considering voltage regulation margin according to claim 1, characterized in that: In voltage mode, calculate the total reactive power demand of the entire wind farm, including: Using the grid connection point voltage as the control object, and the grid connection point reference voltage U ref With actual operating voltage U cur By comparing the values, the deviation voltage ΔU is obtained. The total reactive power demand Q of the entire wind farm is then calculated using a proportional-integral controller. ref The formula is as follows: Q ref =K P (YOU ref -YOU cur )+K I ∫(U ref -YOU cur )dt (1) In the formula: K P K I These are the proportional-integral coefficients, K P Set to U cur The ratio of the reactance of the transmission line between the grid connection point and the wind farm busbar; K I Adjustments were made based on experience.

6. The reactive power and voltage control method for large wind farms considering voltage regulation margin according to claim 1, characterized in that: The control method for the wind turbine operating in load reduction control mode is as follows: Determine the minimum reactive power Q supplied to the grid connection point while ensuring stable grid voltage. L Because the output power of the wind turbine meets Furthermore, the closer a wind turbine is to its rated state, the greater the reactive power released by the same power reduction. Therefore, it is necessary to determine the load reduction priority of each unit and select wind turbines for load reduction control.

7. A reactive power and voltage control device for a large wind farm considering voltage regulation margin, employing the reactive power and voltage control method for a large wind farm considering voltage regulation margin as described in claim 1, characterized in that, The wind farm includes a reactive power compensation device and wind turbine generators. The device is used in the wind farm and includes: The calculation unit is used to calculate the total reactive power demand of the entire wind farm in voltage mode. The first judgment unit is used to determine whether the reactive power compensation requirement is met. When the reactive power compensation requirement is met, reactive power adjustment is performed through the reactive power compensation device. If the reactive power compensation device cannot meet the reactive power compensation amount, the wind turbine is used for reactive power compensation. The second judgment unit is used to determine whether the reactive power capacity of the wind turbine is sufficient. When the reactive power capacity of the wind turbine is sufficient, the wind turbine operates in the adaptive droop control mode. When the reactive power capacity of the wind turbine is insufficient, the wind turbine operates in the load reduction control mode.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When executed by a processor, the program implements the steps of the method according to any one of claims 1 to 6.

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