Method and system for judging frequency regulation capability of wind power support system

Abstract

The invention discloses a method and a system for judging the frequency regulation capability of a wind power support system, and relates to the technical field of frequency regulation, and the method comprises the following steps: S1, carrying out the combined control of the kinetic energy and load shedding of a rotor; s2, analyzing the frequency modulation capability of different types of wind generating sets; s3, improving the frequency modulation capability of the wind turbine generator; and S4, judging the frequency modulation capability. In order to give full play to the frequency modulation potential of the wind turbine generator, an overspeed load shedding area and a variable-pitch load shedding area are divided, the frequency response characteristic of the wind turbine generator can be further improved, the wind turbine generator of a wind power plant is divided into a non-frequency-modulation type, a general frequency modulation type and a priority frequency modulation type, the frequency modulation capacity of the wind turbine generator is analyzed, and the frequency modulation efficiency is improved. The frequency modulation capabilities of the wind turbine generators in the low-wind-speed area, the medium-wind-speed area and the high-wind-speed area are respectively improved by improving the active power output of the wind turbine generators, so that the frequency modulation capabilities of the wind turbine generators in the low-wind-speed area, the medium-wind-speed area and the high-wind-speed area are further respectively judged.

Description

Technical Field

[0001] This invention relates to the field of frequency regulation technology, specifically to a method and system for determining the frequency regulation capability of a wind power support system. Background Technology

[0002] The wind power support system includes wind turbine generators, wind power support foundations, and power transmission control systems. These structures ensure the stable operation of wind turbine generators and the effective transmission of electrical energy. Chinese patent 202310494122.X discloses "a method for determining the frequency regulation capability of a wind power support system, including acquiring the working data information of the target power grid system, calculating the equivalent inertia time constant after the new energy power generation system is connected, calculating the critical value of the equivalent inertia time constant of the system, calculating the capacity of the wind turbine generator to participate in the system frequency regulation when the equivalent inertia requirement of the system is met, calculating the support index, and determining the frequency regulation capability of the wind power support system based on the support index."

[0003] The aforementioned document enables a quantitative assessment of the frequency regulation capability of the support system for new energy units. However, large-scale wind power support systems typically consist of a large number of wind turbine units. Due to differences in the geographical location, model, and operating status of the units, each unit releases different rotor kinetic energy when the load disturbance frequency changes. If all units participate in grid frequency regulation, the frequency regulation capability of each unit cannot be fully utilized. Therefore, it is necessary to differentiate the units while also considering the interaction between them. However, current research mainly relies on wind speed to classify wind turbine units, without considering their power-limited operating state, which results in the wind farm being unable to utilize the frequency regulation capability of the units during frequency regulation. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for determining the frequency regulation capability of a wind power support system, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method and system for determining the frequency regulation capability of a wind power support system, comprising the following steps;

[0006] S1. Joint control of rotor kinetic energy and load reduction: The operating area of ​​the wind turbine is divided into an overspeed load reduction zone and a pitch load reduction zone. In the overspeed load reduction zone, rotor kinetic energy control and overspeed control work together. In the pitch load reduction zone, rotor kinetic energy control and pitch angle control work together. Rotor kinetic energy control is added to the power control of the wind turbine to realize joint control of rotor kinetic energy and load reduction, and fully utilize the frequency regulation potential of the wind turbine.

[0007] S2. Analysis of the frequency regulation capability of different types of wind turbine generator sets: Wind turbine generator sets are divided into non-frequency regulation type, general frequency regulation type and priority frequency regulation type. The frequency regulation capability of wind turbine generator sets is analyzed using two indicators: active power output and release of rotor kinetic energy.

[0008] S3. Improve the frequency regulation capability of wind turbines: For priority frequency regulation types, the adjustment capability of rotor kinetic energy control also depends on wind speed and the operating status of wind turbines. When there is a sudden increase in load and the grid frequency drops, for wind turbines in low wind speed areas, the active power output of wind turbines is increased by adjusting the speed. For wind turbines in medium wind speed areas, the output power of wind turbines is increased by adjusting the speed and pitch angle. For wind turbines in high wind speed areas, the active power output of the unit is increased by enabling variable pitch angle, thereby improving the frequency regulation capability of wind turbines.

[0009] S4. Frequency regulation capability assessment: The frequency regulation capability of wind turbines in low wind speed area, medium wind speed area and high wind speed area are assessed respectively.

[0010] Preferably, in step S1, rotor kinetic energy control utilizes rotor kinetic energy to participate in system frequency regulation. The kinetic energy contained in the wind turbine rotor is expressed as follows: Where J represents the mechanical moment of inertia of the wind turbine, ω represents the rotor speed of the wind turbine, and the change in the rotor's kinetic energy before and after the change in speed is: ω1 and ω2 represent the rotational speeds of the front and rear rotors, respectively, and the rotor speeds are used to respond promptly to changes in the system frequency.

[0011] Preferably, in step S1, the overspeed control calculates the reference speed based on the wind turbine's output and load reduction level to achieve load reduction operation;

[0012] Pitch angle control calculates the pitch angle after load reduction based on the wind turbine output, the corrected load reduction level, and the initial pitch angle, thus maintaining system frequency stability.

[0013] Preferably, in step S2, the rotor speed of the wind turbine during normal operation satisfies:

[0014] {ω|ω min <ω<ω max}

[0015] In the formula, ω min ω represents the minimum rotor speed of the wind turbine. max This indicates the maximum permissible rotational speed of the wind turbine rotor;

[0016] When the rotor speed of the wind turbine is at the minimum speed ω min When the wind turbine's rotor speed is between and including the critical speed ω1, it does not participate in frequency regulation.opt Between and including the optimal speed ω opt During operation, it automatically participates in frequency regulation when the rotor speed of the wind turbine is greater than the optimal speed ω. opt At that time, priority will be given to participating in frequency modulation.

[0017] Preferably, in step S2, when the rotor speed of the non-frequency-adjustable wind turbine is lower than the critical speed, the output power of the unit compensated by the kinetic energy released by the rotor is less than the power before the grid frequency drops, indicating that the kinetic energy released by the wind turbine by reducing the speed cannot complete the frequency regulation.

[0018] For non-frequency-tuned types, the speed and output power meet the following requirements:

[0019] {(ω,P out )|ω min ≤ω≤ω1,P out <P opt}

[0020] In the formula, ω1 represents the critical speed of the rotor, and P out Indicates output power, ω min P represents the minimum rotor speed of the wind turbine, ω represents the current rotor speed, and P represents the minimum rotor speed of the wind turbine. opt This represents the power reference value of a wind turbine operating in MPPT mode at a certain wind speed.

[0021] The output power of the general frequency-regulated wind turbine is higher than the power before the grid frequency drops, providing frequency regulation. The speed and output power of the general frequency-regulated wind turbine meet the following requirements:

[0022] {(ω,P out |ω1<ω≤ω opt ,P out ≥P opt}

[0023] In the formula, ω1 represents the critical speed of the rotor, and P out Indicates output power, ω opt P represents the optimal rotor speed of the wind turbine, ω represents the current rotor speed, and P represents the current rotor speed. opt This represents the power reference value of a wind turbine operating in MPPT mode at a certain wind speed.

[0024] The wind turbines of the priority frequency regulation type are in a power-limited state, and their speed meets the following requirements:

[0025] {ω|ω opt <ω≤ω max}

[0026] In the formula, ω represents the current rotor speed. max ω represents the maximum permissible rotor speed of the wind turbine. optThis indicates the optimal speed of the wind turbine.

[0027] Preferably, for wind turbines with priority frequency regulation, the initial operating speed and output power of the wind turbine unit meet the following requirements:

[0028] {(ω,P out )|ω opt <ω≤ω max ,P out <P opt}

[0029] In the formula, ω represents the current rotor speed. max ω represents the maximum permissible rotor speed of the wind turbine. opt P represents the optimal speed of the wind turbine. out P represents output power. opt This represents the power reference value of a wind turbine operating in MPPT mode at a certain wind speed.

[0030] When the load suddenly increases, the rotor speed drops to the optimal speed ω. opt For determining the frequency regulation capability of wind turbines in low-wind-speed areas, the output power of the wind turbine is increased to the power reference value P of the wind turbine operating in MPPT mode in low-wind-speed areas. opt The frequency regulation capability ΔP1 of the wind turbine is:

[0031]

[0032] In the formula, ΔP1 represents the frequency regulation capability of the wind turbine, ω represents the current rotor speed, and ω max This represents the maximum permissible speed of the rotor, and |·| represents the absolute value.

[0033] Determining the frequency regulation capability of wind turbines in medium wind speed areas:

[0034]

[0035] In the formula, ΔP2 represents the frequency regulation capability of the wind turbine, ω and β represent the current rotor speed and pitch angle, respectively, and β min β represents the minimum pitch angle. max This represents the maximum permissible pitch angle, k1 and k2 represent the weighting coefficients for speed change and pitch change, respectively, where k1 + k2 = 1, |·| represents the absolute value, and P opt This represents the power reference value of the wind turbine operating in MPPT mode at medium wind speeds, ω. opt Indicates the optimal rotational speed;

[0036] Determining the frequency regulation capability of wind turbines in high-wind-speed areas:

[0037]

[0038] In the formula, ΔP3 represents the frequency regulation capability of the wind turbine, β represents the current pitch angle, and β min β represents the minimum pitch angle. max P represents the maximum permissible pitch angle, |·| represents the absolute value. opt This represents the power reference value of the wind turbine operating in MPPT mode at high wind speeds.

[0039] Preferably, in step S4, determining the values ​​of the speed change weight coefficient k1 and the pitch change weight coefficient k2 is an important factor in determining the frequency regulation capability of the unit. The speed change weight coefficient k1 and the pitch change weight coefficient k2 are determined using the coefficient of variation.

[0040] The wind power support system includes wind turbine generators, wind power support foundations, and a power transmission and control system. The coefficient of variation (COP) measures the degree of variation in wind turbine generator parameters within the support system; it is defined as the ratio of its standard deviation to its mean. The current wind speed, rotational speed, and pitch angle of the wind turbine generator are used as inputs to the COP. Let the time series of rotational speed and pitch angle be ω. i and β i ;

[0041] The specific process for determining the power regulation capability of wind turbine units using the coefficient of variation is as follows:

[0042] A1. Obtain the wind turbine generator at wind speed v i Rotation speed and pitch angle at that time;

[0043] A2. Calculate the wind turbine speed sequence ω i and propeller pitch angle sequence β i The standard deviation and mean of;

[0044] A3. Calculate the coefficient of variation of rotational speed and pitch angle;

[0045] A4. Calculate the weighting coefficients for speed change and pitch change.

[0046] The frequency regulation capability assessment system for wind power support systems includes the following units:

[0047] The joint frequency modulation unit is used to divide the operating area of ​​the wind turbine into an overspeed load reduction zone and a pitch load reduction zone, and to incorporate rotor kinetic energy control into the power control of the wind turbine, so as to realize the joint control of rotor kinetic energy and load reduction and fully utilize the frequency modulation potential of the wind turbine.

[0048] The frequency regulation classification unit divides wind turbine generators into non-frequency regulation, general frequency regulation, and priority frequency regulation categories, and analyzes the frequency regulation capabilities of different types of wind turbine generators using two indicators: active power output and rotor kinetic energy release.

[0049] A frequency regulation capability optimization unit, which improves the frequency regulation capability of wind turbines in low wind speed areas, medium wind speed areas and high wind speed areas respectively;

[0050] The frequency regulation capability determination unit determines the frequency regulation capability of wind turbines in low wind speed, medium wind speed and high wind speed areas respectively.

[0051] Compared with the prior art, the beneficial effects of the present invention are:

[0052] This invention provides inertial support through rotor kinetic energy control and active power reserve through load shedding control. Combining these two technologies further improves the frequency response characteristics of wind turbines. To fully utilize the frequency regulation potential of wind turbines, the invention divides the overspeed load shedding zone and the pitch load shedding zone, and classifies the turbines in the wind farm into non-frequency-regulating, general frequency-regulating, and priority frequency-regulating categories. By utilizing active power output and rotor kinetic energy release as indicators, the invention analyzes the frequency regulation capability of wind turbines. Considering that the adjustment capability of rotor kinetic energy control also depends on wind speed and the operating status of each wind turbine, the invention improves the frequency regulation capability of wind turbines in low-wind-speed, medium-wind-speed, and high-wind-speed zones by increasing the active power output of the turbines. This allows for further determination of the frequency regulation capability of wind turbines in low-wind-speed, medium-wind-speed, and high-wind-speed zones. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the overall method flow provided in the embodiments of the present invention;

[0054] Figure 2 This is a schematic diagram of the overall system structure provided for an embodiment of the present invention. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Please see Figures 1 to 2 This invention provides a technical solution: a method and system for determining the frequency regulation capability of a wind power support system, comprising the following steps:

[0057] S1. Joint control of rotor kinetic energy and load reduction: The operating area of ​​the wind turbine is divided into an overspeed load reduction zone and a pitch load reduction zone. In the overspeed load reduction zone, rotor kinetic energy control and overspeed control work together. In the pitch load reduction zone, rotor kinetic energy control and pitch angle control work together. Rotor kinetic energy control is added to the power control of the wind turbine to realize joint control of rotor kinetic energy and load reduction, and fully utilize the frequency regulation potential of the wind turbine.

[0058] S2. Analysis of the frequency regulation capability of different types of wind turbine generator sets: Wind turbine generator sets are divided into non-frequency regulation type, general frequency regulation type and priority frequency regulation type. The frequency regulation capability of wind turbine generator sets is analyzed using two indicators: active power output and release of rotor kinetic energy.

[0059] S3. Improve the frequency regulation capability of wind turbines: For priority frequency regulation types, the adjustment capability of rotor kinetic energy control also depends on wind speed and the operating status of wind turbines. When there is a sudden increase in load and the grid frequency drops, for wind turbines in low wind speed areas, the active power output of wind turbines is increased by adjusting the speed. For wind turbines in medium wind speed areas, the output power of wind turbines is increased by adjusting the speed and pitch angle. For wind turbines in high wind speed areas, the active power output of the unit is increased by enabling variable pitch angle, thereby improving the frequency regulation capability of wind turbines.

[0060] S4. Frequency regulation capability assessment: The frequency regulation capability of wind turbines in low wind speed area, medium wind speed area and high wind speed area are assessed respectively.

[0061] In step S1, rotor kinetic energy control utilizes rotor kinetic energy to participate in system frequency regulation. The kinetic energy contained in the wind turbine rotor is expressed as: Where J represents the mechanical moment of inertia of the wind turbine, ω represents the rotor speed of the wind turbine, and the change in the rotor's kinetic energy before and after the change in speed is: ω1 and ω2 represent the rotational speeds of the front and rear rotors, respectively, and the rotor speeds are used to respond promptly to changes in the system frequency.

[0062] In step S1, the overspeed control calculates the reference speed based on the wind turbine's output and load reduction level to achieve load reduction operation;

[0063] The reference speed for overspeed control is obtained using the following formula:

[0064]

[0065] In the formula, ω opt P represents the optimal speed under maximum power point tracking. mppt P represents the output of the wind turbine under maximum power point tracking. ret P represents the reference power. det Indicates the unloaded power, ω maxIndicates the maximum speed of the fan;

[0066] Pitch angle control calculates the pitch angle after load reduction based on the wind turbine output, the corrected load reduction level, and the initial pitch angle, to maintain system frequency stability.

[0067] The specific formula for adjusting the load reduction level is as follows:

[0068]

[0069] In the formula, d' represents the corrected load reduction level, d represents the original load reduction level, K represents the correction coefficient, the magnitude of the correction coefficient directly affects the frequency regulation capability of the wind turbine, Δf represents the frequency deviation, and f0 represents the reference frequency.

[0070] In step S2, the rotor speed of the wind turbine during normal operation satisfies:

[0071] {ω|ω min <ω<ω max}

[0072] In the formula, ω min ω represents the minimum rotor speed of the wind turbine. max This indicates the maximum permissible rotational speed of the wind turbine rotor;

[0073] When the rotor speed of the wind turbine is at the minimum speed ω min When the wind turbine's rotor speed is between and including the critical speed ω1, it does not participate in frequency regulation. opt Between and including the optimal speed ω opt During operation, it automatically participates in frequency regulation when the rotor speed of the wind turbine is greater than the optimal speed ω. opt At that time, priority will be given to participating in frequency modulation;

[0074] In step S2, when the rotor speed of a non-frequency-regulated wind turbine is lower than the critical speed, the output power of the turbine compensated by the kinetic energy released by the rotor is less than the power before the grid frequency drops, indicating that the kinetic energy released by the wind turbine by reducing the speed cannot complete the frequency regulation.

[0075] For non-frequency-tuned types, the speed and output power meet the following requirements:

[0076] {(ω,P out )|ω min ≤ω≤ω1,P out <P opt}

[0077] In the formula, ω1 represents the critical speed of the rotor, and P out Indicates output power, ω min P represents the minimum rotor speed of the wind turbine, ω represents the current rotor speed, and P represents the minimum rotor speed of the wind turbine.opt This represents the power reference value of a wind turbine operating in MPPT mode at a certain wind speed.

[0078] Generally, the output power of frequency-regulated wind turbines is higher than the power before the grid frequency drops, providing frequency regulation. The speed and output power of frequency-regulated turbines generally meet the following requirements:

[0079] {(ω,P out |ω1<ω≤ω opt ,P out ≥P opt}

[0080] In the formula, ω1 represents the critical speed of the rotor, and P out Indicates output power, ω opt P represents the optimal rotor speed of the wind turbine, ω represents the current rotor speed, and P represents the current rotor speed. opt This represents the power reference value of a wind turbine operating in MPPT mode at a certain wind speed.

[0081] Wind turbines with priority frequency regulation are in a power-limited state, and the speed meets the following requirements:

[0082] {ω|ω opt <ω≤ω max}

[0083] In the formula, ω represents the current rotor speed. max ω represents the maximum permissible rotor speed of the wind turbine. opt This indicates the optimal speed of the wind turbine.

[0084] For wind turbines with priority frequency regulation, the initial operating speed and output power must meet the following requirements:

[0085] {(ω,P out )|ω opt <ω≤ω max ,P out <P opt}

[0086] In the formula, ω represents the current rotor speed. max ω represents the maximum permissible rotor speed of the wind turbine. opt P represents the optimal speed of the wind turbine. out P represents output power. opt This represents the power reference value of a wind turbine operating in MPPT mode at a certain wind speed.

[0087] When the load suddenly increases, the rotor speed drops to the optimal speed ω. opt For determining the frequency regulation capability of wind turbines in low-wind-speed areas, the output power of the wind turbine is increased to the power reference value P of the wind turbine operating in MPPT mode in low-wind-speed areas.opt The frequency regulation capability ΔP1 of the wind turbine is:

[0088]

[0089] In the formula, ΔP1 represents the frequency regulation capability of the wind turbine, ω represents the current rotor speed, and ω max This represents the maximum permissible speed of the rotor, and |·| represents the absolute value.

[0090] Determining the frequency regulation capability of wind turbines in medium wind speed areas:

[0091]

[0092] In the formula, ΔP2 represents the frequency regulation capability of the wind turbine, ω and β represent the current rotor speed and pitch angle, respectively, and β min β represents the minimum pitch angle. max This represents the maximum permissible pitch angle, k1 and k2 represent the weighting coefficients for speed change and pitch change, respectively, where k1 + k2 = 1, |·| represents the absolute value, and P opt This represents the power reference value of the wind turbine operating in MPPT mode at medium wind speeds, ω. opt Indicates the optimal rotational speed;

[0093] Determining the frequency regulation capability of wind turbines in high-wind-speed areas:

[0094]

[0095] In the formula, ΔP3 represents the frequency regulation capability of the wind turbine, β represents the current pitch angle, and β min β represents the minimum pitch angle. max P represents the maximum permissible pitch angle, |·| represents the absolute value. opt This represents the power reference value of the wind turbine operating in MPPT mode at high wind speeds;

[0096] Low wind speed area: refers to a wind area with an average wind speed of less than 4 m / s;

[0097] Medium wind speed zone: refers to wind zones with average wind speeds between 4 and 6 meters per second;

[0098] High wind speed area: refers to wind areas with an average wind speed exceeding 8 meters per second;

[0099] In step S4, determining the values ​​of the speed change weighting coefficient k1 and the pitch change weighting coefficient k2 is an important factor in determining the frequency regulation capability of the unit. The speed change weighting coefficient k1 and the pitch change weighting coefficient k2 are determined using the coefficient of variation.

[0100] The wind power support system includes wind turbine generators, wind power support foundations, and a power transmission and control system. The coefficient of variation (COP) measures the degree of variation in wind turbine generator parameters within the support system; it is defined as the ratio of its standard deviation to its mean. The current wind speed, rotational speed, and pitch angle of the wind turbine generator are used as inputs to the COP. Let the time series of rotational speed and pitch angle be ω. i and β i ;

[0101] The specific process for determining the power regulation capability of wind turbine units using the coefficient of variation is as follows:

[0102] A1. Obtain the wind turbine generator at wind speed v i Rotation speed and pitch angle at that time;

[0103] A2. Calculate the wind turbine speed sequence ω i and propeller pitch angle sequence β i The standard deviation and mean of;

[0104] A3. Calculate the coefficient of variation of rotational speed and pitch angle;

[0105]

[0106] In the formula, C vω,i C represents the coefficient of variation of rotational speed. vβ,i δ represents the coefficient of variation of pitch control. ω,i and δ β,i Representing the wind turbine speed sequence ω i and propeller pitch angle sequence β i Standard deviation, μ ω,i and μ β,i Representing the wind turbine speed sequence ω i and propeller pitch angle sequence β i The average value;

[0107] A4. Calculate the weighting coefficients for speed change and pitch control;

[0108]

[0109] In the formula, k1 represents the weighting coefficient of the speed change, and k2 represents the weighting coefficient of the pitch change.

[0110] The frequency regulation capability assessment system for wind power support systems includes the following units:

[0111] The joint frequency regulation unit is used to divide the operating area of ​​the wind turbine into the overspeed load reduction zone and the pitch load reduction zone, and to add rotor kinetic energy control to the power control of the wind turbine, so as to realize the joint control of rotor kinetic energy and load reduction, and fully utilize the frequency regulation potential of the wind turbine.

[0112] The frequency regulation classification unit divides wind turbines into non-frequency regulation, general frequency regulation, and priority frequency regulation categories, and analyzes the frequency regulation capabilities of different types of wind turbines using two indicators: active power output and rotor kinetic energy release.

[0113] The frequency regulation capability optimization unit improves the frequency regulation capability of wind turbines in low-wind-speed, medium-wind-speed, and high-wind-speed areas respectively.

[0114] The frequency regulation capability determination unit determines the frequency regulation capability of wind turbines in low-wind-speed, medium-wind-speed, and high-wind-speed areas respectively.

[0115] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0116] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for determining the frequency regulation capability of a wind power support system, characterized in that: The method comprises the following steps: S1. Combined control of rotor kinetic energy and load reduction: The operation area of ​​the wind turbine is divided into an overspeed load reduction area and a variable pitch load reduction area. In the overspeed load reduction area, the rotor kinetic energy control and overspeed control work together. In the variable pitch load reduction area, the rotor kinetic energy control and pitch angle control work together. The rotor kinetic energy control is added to the power control of the wind turbine to achieve combined control of the rotor kinetic energy and load reduction, and give full play to the frequency regulation potential of the wind turbine. S2. Analyze the frequency regulation capability of different types of wind turbines: Wind turbines are divided into non-frequency regulation, general frequency regulation and priority frequency regulation, and the frequency regulation capability of wind turbines is analyzed using the two indicators of active power output and released rotor kinetic energy; S3. Improve the frequency regulation capability of wind turbines: For priority frequency regulation, the regulation capability of rotor kinetic energy control also depends on the wind speed and the operating status of wind turbines. When the load suddenly increases and the grid frequency drops, for wind turbines in low wind speed areas, the active output of wind turbines is increased by adjusting the speed. For wind turbines in medium wind speed areas, the output power of wind turbines is increased by adjusting the speed and pitch angle. For wind turbines in high wind speed areas, the active output of wind turbines is increased by enabling variable pitch angles, thereby improving the frequency regulation capability of wind turbines. S4. Determination of frequency regulation capability: Determine the frequency regulation capability of wind turbines in low wind speed area, wind turbines in medium wind speed area and wind turbines in high wind speed area respectively.

2. The method for determining the frequency regulation capability of a wind power support system according to claim 1, characterized in that: In step S1, the rotor kinetic energy control uses the rotor kinetic energy to participate in the system frequency regulation. The kinetic energy contained in the wind turbine rotor is expressed as: Where J represents the mechanical moment of inertia of the wind turbine, ω represents the rotor speed of the wind turbine, and the change in the kinetic energy of the rotor before and after the speed changes is: ω1 and ω2 respectively represent the speed of the front and rear rotors, and the rotor speed is used to respond to changes in the system frequency in a timely manner.

3. The method for determining the frequency regulation capability of a wind power support system according to claim 1, characterized in that: In step S1, the overspeed control calculates the reference speed according to the output of the wind turbine and the load reduction level to achieve load reduction operation; The pitch angle control calculates the load-reduced pitch angle based on the output of the wind turbine, the corrected load-reduction level and the initial pitch angle to maintain the system frequency stability.

4. The method for determining the frequency regulation capability of a wind power support system according to claim 1, characterized in that: In step S2, the rotor speed of the wind turbine in normal operation satisfies: {oh|oh min <ω<ω max } In the formula, ω min Indicates the minimum rotor speed of the wind turbine, ω max Indicates the maximum permissible rotor speed of the wind turbine; When the rotor speed of the wind turbine is at the minimum speed ω min When the wind turbine rotor speed is between the critical speed ω1 and the optimal speed ω1, it does not participate in frequency regulation. opt Between and including the optimal speed ω opt During operation, it automatically participates in frequency regulation. When the rotor speed of the wind turbine is greater than the optimal speed ω opt When the frequency is adjusted, priority is given to frequency modulation.

5. The method for determining the frequency regulation capability of a wind power support system according to claim 4, characterized in that: In step S2, when the rotor speed of the non-frequency-regulated wind turbine is lower than the critical speed, the output power of the turbine compensated by the kinetic energy released by the rotor is less than the power before the grid frequency drops, indicating that the kinetic energy released by the wind turbine by reducing the speed cannot complete the frequency regulation; The speed and output power of non-frequency-modulated equipment meet the following requirements: {(ω,P out )|ω min ≤ω≤ω1,P out <P opt } Where ω1 represents the critical speed of the rotor, P out represents the output power, ω min represents the minimum rotor speed of the wind turbine, ω represents the current rotor speed, P opt It indicates the power reference value of the wind turbine operating in MPPT mode at a certain wind speed; The output power of the general frequency-modulation type wind turbine is higher than the power before the grid frequency drops, providing frequency regulation. The speed and output power of the general frequency-modulation type meet the following requirements: {(ω,P out )|ω1<ω≤ω opt ,P out ≥P opt } Where ω1 represents the critical speed of the rotor, P out represents the output power, ω opt represents the optimal rotor speed of the wind turbine, ω represents the current rotor speed, P opt It indicates the power reference value of the wind turbine operating in MPPT mode at a certain wind speed; The wind turbines of the priority frequency regulation type are in a power-limited state, and the speed satisfies: {oh|oh opt <ω≤ω max } Where ω represents the current rotor speed, ω max Indicates the maximum permissible rotor speed of the wind turbine, ω opt Indicates the optimal speed of the wind turbine.

6. The method for determining the frequency regulation capability of a wind power support system according to claim 5, characterized in that: For the priority frequency regulation category, the initial operating speed and output power of the wind turbine generator set shall meet the following requirements: {(ω,P out )|ω opt <ω≤ω max ,P out <P opt } Where ω represents the current rotor speed, ω max Indicates the maximum permissible rotor speed of the wind turbine, ω opt Represents the optimal speed of the wind turbine, P out Indicates output power, P opt It indicates the power reference value of the wind turbine operating in MPPT mode at a certain wind speed; When the load increases suddenly, the rotor speed decreases to the optimal speed ω opt For the frequency regulation capability of wind turbines in low wind speed areas, the output power of wind turbines is increased to the power reference value P of wind turbines in low wind speed areas working in MPPT mode. opt , the frequency regulation capability of wind turbine generator set ΔP1 is: In the formula, ΔP1 represents the frequency regulation capability of the wind turbine, ω represents the current rotor speed, and ω max represents the maximum allowable rotor speed, and |·| represents the absolute value; Determination of frequency regulation capability of wind turbines in medium wind speed areas: In the formula, ΔP2 represents the frequency regulation capability of the wind turbine, ω and β represent the current rotor speed and pitch angle respectively, and β min represents the minimum pitch angle, β max represents the maximum allowable pitch angle, k1 and k2 represent the weight coefficients of variable speed and variable pitch, respectively, where k1+k2=1, |·| represents the absolute value, P opt Indicates the power reference value of the wind turbine operating in MPPT mode at medium wind speed, ω opt Indicates the optimal speed; Determination of frequency regulation capability of wind turbines in high wind speed areas: In the formula, ΔP3 represents the frequency regulation capability of the wind turbine, β represents the current pitch angle, and β min represents the minimum pitch angle, β max represents the maximum allowable pitch angle, |·| represents the absolute value, P opt It indicates the power reference value of the wind turbine operating in MPPT mode at high wind speed.

7. The method for determining the frequency regulation capability of a wind power support system according to claim 6, characterized in that: In the step S4, determining the values ​​of the speed change weight coefficient k1 and the pitch change weight coefficient k2 is an important factor in determining the frequency regulation capability of the unit, and the speed weight coefficient k1 and the pitch change weight coefficient k2 are determined by using the coefficient of variation; The wind power support system includes wind turbines, wind power support foundations and power transmission control systems. The coefficient of variation is a measure of the degree of variation of wind turbine indicators in the wind power support system. It is defined as the ratio of its standard deviation to its mean value. The current wind speed, rotation speed and pitch angle of the wind turbine are used as inputs of the coefficient of variation. The time series of rotation speed and pitch angle are ω i and β i ; The specific process of using the coefficient of variation to determine the power regulation capability of wind turbines is as follows: A1. Obtain the wind turbine generator system at wind speed v i The rotation speed and pitch angle at A2. Obtain the wind turbine speed sequence ω i and the pitch angle sequence β i The standard deviation and mean of A3. Calculate the coefficient of variation of the rotation speed and pitch angle; A4. Calculate the weight coefficients of speed change and pitch change.

8. A frequency regulation capability determination system for a wind power support system, characterized in that: The frequency regulation capability determination system of the wind power support system is applicable to the frequency regulation capability determination method of the wind power support system according to claims 1 to 7, and comprises the following units: A combined frequency regulation unit, which is used to divide the operation area of ​​the wind turbine into an overspeed load reduction area and a pitch-changing load reduction area, and add rotor kinetic energy control to the power control of the wind turbine to achieve combined control of rotor kinetic energy and load reduction, and give full play to the frequency regulation potential of the wind turbine; A frequency regulation classification unit, wherein the frequency regulation classification unit classifies wind turbines into a non-frequency regulation class, a general frequency regulation class, and a priority frequency regulation class, and analyzes the frequency regulation capabilities of different types of wind turbines; A frequency regulation capability optimization unit, wherein the frequency regulation capability optimization unit improves the frequency regulation capability of wind turbines in low wind speed area, medium wind speed area and high wind speed area respectively for priority frequency regulation categories; A frequency regulation capability determination unit is used to determine the frequency regulation capability of wind turbines in low wind speed area, medium wind speed area and high wind speed area respectively.

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