A method and system for controlling virtual inertia of a fan based on system inertia requirements

Abstract

The application provides a fan virtual inertia control method and system based on system inertia demand, comprising the following steps: firstly, evaluating the virtual inertia demand of the system to the fan under different wind power penetration rates and power disturbances according to the system frequency change rate constraint; secondly, determining the virtual inertia action time of the fan according to the grid connection standard; thirdly, according to the fan power response principle, the virtual inertia control strategy of the fan based on the system inertia demand is proposed through speed tracking control, and the controller parameters are adjusted according to the virtual inertia demand so that the inertia size of the fan meets the demand. The method can quantitatively control the virtual inertia of the fan according to the virtual inertia demand of the system to the fan, so that the virtual inertia of the fan always meets the system demand.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of virtual inertia demand evaluation and control of new energy high-penetration power systems, in particular to a wind turbine virtual inertia control method and system based on system inertia demand. BACKGROUND

[0002] With the large-scale access of new energy power generation equipment to the power system, the system inertia level is continuously declining, which seriously affects the frequency safety of the system after power disturbance. As a large rotating equipment, wind turbines can have similar inertial response capability as synchronous machines by changing the speed through additional control, but the size of the inertia provided by the inertial response of the wind turbine cannot be known in advance. In the actual control process of the wind turbine, the large change in the speed in a short time will bring problems such as power overshoot, increase in mechanical load, and difficulty in speed recovery, so the wind turbine should perform inertial response under the premise of considering the system inertia demand. Therefore, how to evaluate the virtual inertia demand of the system on the wind turbine and make the size of the inertia shown by the inertial response of the wind turbine through additional control meet the system inertia demand has become a problem to be solved. SUMMARY

[0003] To solve the above problems, the purpose of the present application is a wind turbine virtual inertia control method and system based on system inertia demand, which can evaluate the virtual inertia demand of the system on the wind turbine under different wind power penetration rates and power disturbances according to the system frequency change rate constraint, and complete the quantitative control of the virtual inertia of the wind turbine using the speed tracking performance of the wind turbine, so that the virtual inertia shown by the wind turbine meets the demand.

[0004] To achieve the above technical purpose, the present application provides a wind turbine virtual inertia control method based on system inertia demand, comprising the following steps:

[0005] According to the system frequency change rate constraint of the wind turbine, the virtual inertia demand of the wind power high-penetration system on the wind turbine is obtained, wherein the system frequency change rate constraint is used to represent the constraint condition of the frequency change rate of the wind power high-penetration system;

[0006] According to the wind power grid connection standard, the virtual inertia action time of the wind turbine is obtained, wherein the power generation equipment of the wind power grid connection system is composed of synchronous machines and wind turbines, and the virtual inertia action time is used to represent the time for the wind turbine to complete the inertial response in the process of frequency drop or rise to the frequency deviation extreme value;

[0007] Based on the virtual inertia demand, according to the wind turbine power response principle, the wind turbine virtual inertia control strategy of the wind turbine is generated according to the virtual inertia action time.

[0008] Preferably, in the process of obtaining the virtual inertia demand, a first expression for representing the system frequency rate of change constraint is generated by obtaining the system maximum frequency rate of change based on the system minimum inertia demand;

[0009] obtaining a second expression for representing the inertia time constant of the wind power high proportion system when the wind turbine provides virtual inertia;

[0010] the first expression and the second expression are combined to generate a third expression for representing the virtual inertia demand.

[0011] Preferably, in the process of generating the first expression, the second expression and the third expression, the first expression is:

[0012]

[0013] wherein ΔP d is the power disturbance; H sys is the system inertia time constant, H min is the system minimum inertia demand, represents the system frequency rate of change;

[0014] the second expression is:

[0015]

[0016] wherein H g is the synchronous machine inertia time constant; S g is the rated capacity of the synchronous generator; S B is the system rated capacity; k is the wind power penetration rate; H vir is the virtual inertia time constant of the wind turbine;

[0017] the third expression is:

[0018]

[0019] Preferably, in the process of obtaining the virtual inertia action time of the wind turbine, the frequency response equation of the wind power grid-connected system after the power disturbance is constructed as:

[0020]

[0021] wherein H sys is the system inertia time constant, Δf(t) is the frequency deviation signal, ΔP d is the power disturbance, D sys is the load regulation coefficient, ΔP m is the synchronous machine power response signal, ΔP w is the wind turbine power response signal;

[0022] According to the frequency response equation, the virtual inertia action time is obtained.

[0023] Preferably, in the process of constructing the frequency response equation, the system inertia time constant H sys Depends on the capacity of the synchronous machine, expressed as:

[0024] H sys = H g (1-k).

[0025] Preferably, in the process of constructing the frequency response equation, the synchronous machine power response signal ΔP m Equivalent to a first-order inertia signal, expressed as:

[0026]

[0027] Where T g is the primary frequency modulation delay time of the synchronous machine, K sys is the primary frequency modulation coefficient, Δf is the frequency deviation signal, and s is a complex variable;

[0028] The primary frequency modulation coefficient is expressed as:

[0029] K sys = K g (1-k)

[0030] Where K g is the primary frequency modulation coefficient of the synchronous machine.

[0031] Preferably, in the process of constructing the frequency response equation, the expression of the frequency deviation signal Δf(t) is: Where,

[0032]

[0033] Taking the derivative of Δf(t), the virtual inertia action time t vir is obtained, expressed as:

[0034]

[0035] Preferably, in the process of generating the virtual inertia control strategy of the fan, according to the virtual inertia demand, the speed demand of the fan is obtained, wherein the speed demand is used to represent the speed change amount that meets the virtual inertia demand of the fan.

[0036] Based on the speed demand, the virtual inertia control strategy of the fan is generated by introducing a first-order inertia link.

[0037] Preferably, in the process of obtaining the speed demand, a tracking control model for the speed of the fan is constructed to obtain the speed demand.

[0038] The expression of the tracking control model is:

[0039]

[0040] Wherein, ω r0 is the initial speed of the fan, and Δω r is the required speed change amount of the fan to meet the inertia requirement, H vir represents the real-time equivalent inertia time constant in the inertia response process of the fan, and Δf max is the frequency deviation value corresponding to the t vir moment.

[0041] The application discloses a fan virtual inertia control system based on system inertia requirement, comprising:

[0042] A virtual inertia requirement generation module is configured to obtain virtual inertia requirement of a fan by a wind power high-penetration system according to a system frequency change rate constraint, wherein the system frequency change rate constraint is used to represent a constraint condition of the wind power high-penetration system frequency change rate.

[0043] A virtual inertia action time generation module is configured to obtain virtual inertia action time of the fan according to a wind power grid connection standard, wherein the power generation equipment of the wind power grid connection system is composed of synchronous machines and fans, and the virtual inertia action time is used to represent a time for the fan to complete inertia response in a process of frequency drop or rise to a frequency deviation extreme value.

[0044] A control strategy generation module is configured to generate a fan virtual inertia control strategy based on virtual inertia requirement, according to a fan power response principle and virtual inertia action time.

[0045] The application discloses the following technical effects:

[0046] The application quantitatively controls virtual inertia of the fan according to virtual inertia requirement of the system to the fan, so that the virtual inertia of the fan can always meet the system requirement. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0048] Figure 1 It is a flow chart of the fan virtual inertia control method based on system inertia requirement of the embodiments of the present application.

[0049] Figure 2is the virtual inertia requirement assessment result of the wind turbine according to the embodiment of the present invention;

[0050] Figure 3 This is a block diagram of the virtual inertia control of a wind turbine according to an embodiment of the present invention;

[0051] Figure 4 This is a simulation topology diagram of a system with a high proportion of wind power according to an embodiment of the present invention;

[0052] Figure 5 is a system dynamic response curve when the load suddenly increases according to an embodiment of the present invention;

[0053] Figure 6 This is the system dynamic response curve when the load suddenly drops according to the embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.

[0055] like Figures 1-6 As shown, the present invention provides a method and system for controlling virtual inertia of a wind turbine based on system inertia requirements. In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand through calculation, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0056] Figure 1 FIG. 1 is a flow chart of a method for controlling wind turbine virtual inertia based on system inertia requirements according to an embodiment of the present invention. Figure 1 As shown, the following steps are included:

[0057] Step 1: Evaluate the virtual inertia requirements of wind turbines in high wind power penetration systems based on frequency change rate constraints.

[0058] Step 2: Analyze and calculate the wind turbine inertia response time according to the wind power grid connection standard;

[0059] Step 3: According to the wind turbine power response principle, a wind turbine virtual inertia control strategy based on system inertia requirements is proposed.

[0060] The inertia of the system with high wind power penetration is significantly reduced, and the virtual inertia of the wind turbine should be set according to the frequency security requirement of the system. At present, foreign researches have proposed relevant standards for the island operation of microgrid, which require that the frequency change rate (df / dt) of the system is not higher than ±0.5 Hz / s. The maximum frequency change rate of the system appears at the initial stage of power disturbance, the primary frequency modulation has not yet acted, and the unbalanced power on the rotor side of the synchronous machine is maximum, at this time, the frequency change rate of the system can be expressed as

[0061]

[0062] In the formula, ΔP d is the size of power disturbance; H sys is the inertia time constant of the system.

[0063] According to the above formula, when the frequency change rate constraint is determined, the inertia requirement of the system can be expressed as

[0064]

[0065] In the formula, H min is the minimum inertia requirement of the system.

[0066] When the wind turbine provides virtual inertia, the inertia time constant of the system with high wind power penetration can be expressed as

[0067]

[0068] In the formula, H g is the inertia time constant of the synchronous machine; S g is the rated capacity of the synchronous generator; S B is the rated capacity of the system; k is the wind power penetration rate; H vir is the virtual inertia time constant of the wind turbine.

[0069] By combining the above two formulas, the virtual inertia requirement of the wind turbine when the system is subjected to power disturbance can be expressed as

[0070]

[0071] By bringing the inertia time constant H g of the synchronous machine and the frequency change rate constraint (df / dt) max into the above formula, the virtual inertia requirement of the wind turbine under different power disturbances and wind power penetration rates can be obtained.

[0072] Figure 2 is the virtual inertia requirement evaluation result of the wind turbine of the embodiment of the present application. As can be seen from Figure 2 , when the disturbance power is small and the wind power penetration rate is low, only the inertia H gThe system inertia requirement can be met. If the penetration rate is lower than 20%, the synchronous machine inertia can cope with disturbances of more than 8%. However, as the wind power penetration rate increases, the system's ability to cope with power disturbances is gradually weakened. When the wind power penetration rate reaches 50%, the system can cope with disturbances of less than 5%, which is not enough to cope with typical faults. At this time, the wind turbine should provide necessary inertia support according to the system requirements. The system's inertia requirement increases with the increase of power disturbances. Under the same power disturbance, the wind turbine virtual inertia requirement can be calculated based on the wind power penetration rate. If ΔP d =0.15pu, the system inertia requirement is 7.5s. When k=20%, the fan needs to provide 17.5s of virtual inertia to bring the total system inertia to 7.5s. When k=50%, the fan needs to provide 10s of virtual inertia to bring the total system inertia to 7.5s.

[0073] Determine and calculate the virtual inertia action time of the wind turbine according to the wind power grid connection standard, specifically including: According to GB / T19963.1-2021 "Technical Regulations for Wind Farm Integration into Power System", the wind turbine needs to have inertia support function after being connected to the system, but the start-up of the additional controller must meet the condition: Δf×df / dt>0. Obviously, the wind turbine should complete the inertial response within the time when the frequency drops or rises to the frequency deviation extreme value. This time is regarded as the virtual inertia action time of the wind turbine, and t is used. vir Assuming that the power generation equipment of the wind power grid-connected system consists of synchronous machines and wind turbines, and the wind power penetration rate is k, the frequency response equation of the system after power disturbance can be expressed as:

[0074]

[0075] Where H sys is the system inertia time constant, Δf(t) is the frequency deviation signal, ΔP d is the power disturbance, D sys is the load adjustment coefficient, generally taken as 1, ΔP m is the synchronous machine power response signal, Δp w is the wind turbine power response signal, where H sys It depends on the proportion of synchronous machine capacity and can be expressed as:

[0076] H sys =H g (1-k) (6)

[0077] Where H g is the inertia time constant of the synchronous machine; k is the wind power penetration rate.

[0078] The power response of the synchronous machine ΔP m It can be equivalent to a first-order inertial signal, which can be expressed as:

[0079]

[0080] Where, T g K is the synchronous machine's frequency modulation delay time, generally 1s; sys is the primary frequency modulation coefficient, which can be expressed as:

[0081] K sys =K g (1-k) (8)

[0082] Where K g is the primary frequency regulation coefficient of the synchronous machine; k is the wind power penetration rate.

[0083] ΔP m Substituting the expression into the system frequency response equation and solving it, the frequency deviation signal Δf(t) after the system is subjected to power disturbance can be expressed as:

[0084]

[0085] Where a, b, c, and d are calculation parameters, which can be expressed as:

[0086]

[0087] Derivative Δf(t) is taken. The moment when the derivative is 0 is the time t taken for the frequency to drop or rise from the initial value to the extreme value of the frequency deviation. vir , which can be expressed as:

[0088]

[0089] Take the typical parameters of synchronous generator: H g =5s, K g =25MW / Hz, when the wind power penetration rate k is 0%, 20%, and 40%, the corresponding tvir is 2.3s, 2.298s, and 2.305s respectively. Therefore, t vir 2.3s is a typical data for the virtual inertia action time of the fan. The fan should complete the virtual inertia support within this time.

[0090] Combined with the system inertia requirements, the wind turbine can use its speed tracking performance to vir Complete virtual inertial support. Figure 3 This is a block diagram of the wind turbine virtual inertia control according to an embodiment of the present invention. The wind turbine virtual inertia controller structure consists of two modules: virtual inertia control and virtual inertia evaluation.

[0091] In the wind turbine virtual inertia assessment module, according to formula (4), the disturbance power and wind power penetration rate are introduced to calculate the wind turbine inertia demand. Based on the evaluation results of the wind turbine inertia demand, the wind turbine speed demand can be calculated. The specific analysis is as follows:

[0092] Real-time equivalent inertia time constant H in the process of fan inertia response vir may be expressed as

[0093]

[0094] In the formula, ΔP w (t) is the real-time inertia support power of the fan. In the variable frequency extreme time, the integral of both sides of the above formula is obtained as

[0095]

[0096] In the formula, Δf max is the frequency deviation value corresponding to t vir . It can be calculated according to formula (9) under the assumption that the system inertia meets the demand. In the process of inertia response of the fan, the rotor motion equation of the wind turbine generator set can be expressed as

[0097]

[0098] In the formula, H w is the inherent inertia time constant of the fan; P we is the electromagnetic power output by the fan; P wm is the mechanical power captured by the fan. By solving the above two formulas, the speed change amount that meets the virtual inertia demand of the fan can be expressed as

[0099]

[0100] In the formula, ω r0 is the initial speed of the fan; Δω r is the speed change amount required by the fan to meet the inertia demand. According to the above formula, the speed change amount Δω r required by the fan under different initial speeds can be obtained by inputting the operating state parameters of the fan and the inertia demand. vir Then, the corresponding speed ω r1 of the fan at t r is ω r0 .

[0101] The virtual inertia control module of the fan generates an additional power signal through speed tracking control to make the real-time speed of the fan track the reference speed. The reference speed ω r_ref is set according to ω r1 . First, in order to ensure that the speed of the fan can change from ω vir to ω r0 within t r1 , the speed tracking control principle is designed based on the rotor motion equation of the fan as follows

[0102]

[0103] In the formula, K p is the speed tracking controller parameter. According to the above formula, the value of K vir at t p can be calculated.

[0104]

[0105] In the formula, ω r_ref is the reference speed; ω r_ref = ω r1 ± Δω r1 ; Δω r1 is the speed change margin. According to the above formula, the value of Kp is calculated, so that the speed of the fan is changed from ω r0 to ω r1 within t vir , thereby realizing the quantitative control of the speed of the fan.

[0106] Secondly, in order to ensure the smooth exit of the fan inertia support power after t vir , a first-order inertia link is introduced. When the speed of the fan changes to ω r1 at t0+t vir , the speed tracking control exits through the first-order inertia link. Under the above control, the fan inertia support power signal can be represented as

[0107]

[0108] In the formula, t0 is the time when the system occurs power disturbance; T is the time parameter of the first-order inertia link, which is 5s.

[0109] Under the control of the above formula, the fan inertia support power is maximum at the initial time of disturbance, which can effectively suppress the frequency change rate; after the frequency reaches the extreme point, the speed changes to the demand evaluation value ω r1 , and the smooth exit of the inertia support power is realized under the action of the first-order inertia link.

[0110] Embodiment 1: Figure 4 is the simulation topology diagram of the high wind power ratio system of the embodiment of the application; this embodiment is based on the DIGSILENT / Power Factory simulation platform to build the IEEE3-machine 9-node wind power high penetration simulation system as shown in Figure 4 . The test system includes three thermal power plants (G1, G2, G3) and a wind farm (DFIG), and the wind power penetration can be changed by adjusting the capacity of the thermal power unit and the fan. It is assumed that the wind speed remains unchanged at 8m / s, and the main parameters of the system are shown in Table 1. The system is set to have a load mutation at t0=2.0s.

[0111] Table 1 System parameters

[0112]

[0113] To verify the effectiveness of the virtual inertia control strategy of wind turbine based on system inertia demand, the simulation example parameters are set as shown in Table 2:

[0114] Table 2 Parameter setting of example

[0115]

[0116] In this example, the wind power penetration rate k = 20%, the power disturbance ΔP d = 0.12pu, according to formula (4), the virtual inertia demand of the wind turbine at this time is 10s. The wind turbine is respectively attached with the traditional differential control and the virtual inertia control strategy of wind turbine based on system inertia demand, and the dynamic response curves of the system after the power disturbance are shown in Figure 5 and Figure 6 .

[0117] Figure 5 is the dynamic response curve of the system when the load suddenly increases according to the embodiment of the present application; when ΔP d > 0, without additional control, the wind turbine hardly responds to the frequency change, the maximum frequency drop amplitude Δf max of the system is -0.61Hz, and the maximum frequency change rate (df / dt) max is -0.67Hz / s, which has exceeded the frequency safety allowable value.

[0118] As shown in Figure 5 (a1)-(a3), when the differential control is used, the speed change amount of the wind turbine within the frequency variation extreme value time t vir is 0.025pu, the maximum frequency change rate (df / dt) max and the drop amplitude Δf max of the system are reduced to -0.54Hz / s and -0.58Hz respectively, but still do not meet the maximum frequency change rate constraint. The H vir of the wind turbine within t vir is 8.79s, which does not meet the inertia demand of the wind turbine under this example. In addition, since the differential control cannot be exited at t vir , the overshoot amount appears in the frequency recovery process, which is not conducive to the frequency safety and stability.

[0119] When the control strategy proposed in the present application is used, the speed change amount of the wind turbine is 0.028pu, the frequency change rate (df / dt) max and the drop amplitude Δf max of the system are reduced to -0.49Hz / s and -0.52Hz respectively, and the H vir of the wind turbine within t vir is 10.98s, which meets the demand of the system for virtual inertia. According to formula (4), the virtual inertia demand of the wind turbine at this time is 10s, which meets the demand of the system for virtual inertia.Figure 5 (b1)~(b3), the smooth exit of the fan inertia support power in the rotational speed tracking control can reduce the overshoot in the system frequency recovery process; and under the action of the first-order inertia link, the inertia support power of the fan is reduced to 0 after experiencing a delay, so that the moment when the rotational speed starts to recover is relatively late, the power absorbed by the fan in the frequency recovery stage is avoided, the system frequency recovery is beneficial, and the frequency modulation effect is better than that of the traditional differential control.

[0120] Figure 6 is the system dynamic response curve when the load of the embodiment of the application suddenly drops; when ΔP d <0, the rotational speed change of the fan under the differential control is 0.026pu, the system frequency change rate (df / dt) max and the drop amplitude Δf max are reduced to 0.54Hz / s and 0.58Hz respectively, the H vir of the fan in t vir is 9.14s, which does not meet the inertia requirement of the fan under the example; under the control strategy provided by the application, the rotational speed change of the fan is 0.029pu, the system frequency change rate (df / dt) max and the drop amplitude Δf max are reduced to 0.48Hz / s and 0.52Hz respectively, the H vir of the fan in t vir is 11.37s, which meets the system virtual inertia requirement.

[0121] The method for controlling the virtual inertia of the fan based on the system inertia requirement provided by the application can quantitatively control the virtual inertia of the fan according to the virtual inertia requirement of the system to the fan, so that the virtual inertia of the fan can always meet the system requirement.

[0122] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other processing device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other processing device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts and / or block diagram. Figure 1 one or more of the blocks or steps in the flowchart or flowchart diagrams. Figure 1 one or more of the blocks or steps in the flowchart or flowchart diagrams.

[0123] In the description of the present application, it is to be understood that the terms "first", "second", "third" and the like, merely identify features belonging to distinct categories, and do not imply or imply a relative importance or a specific number thereof. Thus, a feature identified as "first" or "second" can implicitly or explicitly include one or more of the features. In the description of the present application, the meaning of "a plurality" is two or more, unless otherwise expressly specified.

[0124] Obviously, various modifications and changes can be made to the present application by those skilled in the art without departing from the spirit and scope of the present application. Thus, it is intended that the present application also include such modifications and changes insofar as they come within the scope of the claims of the present application and their equivalents.

Claims

1. A wind turbine virtual inertia control method based on system inertia requirements, characterized in that: The following steps are involved: Obtaining a virtual inertia requirement of the wind power high penetration system for the wind turbine according to a system frequency change rate constraint, wherein the system frequency change rate constraint is used to represent a constraint condition of the frequency change rate of the wind power high penetration system; Obtaining the virtual inertia action time of the wind turbine according to the wind power grid connection standard. The power generation equipment of the wind power grid connection system consists of a synchronous machine and a wind turbine. The virtual inertia action time represents the time it takes for the wind turbine to complete an inertial response when the frequency drops or rises to an extreme frequency deviation value. Based on the virtual inertia requirement, according to the wind turbine power response principle, and according to the virtual inertia action time, a virtual inertia control strategy for the wind turbine is generated, specifically: In the process of generating the virtual inertia control strategy of the wind turbine, a speed requirement of the wind turbine is obtained according to the virtual inertia requirement, wherein the speed requirement is used to represent a speed change amount that satisfies the virtual inertia requirement of the wind turbine; Based on the speed requirement, the wind turbine virtual inertia control strategy is generated by introducing a first-order inertia link; In the process of obtaining the speed demand, a tracking control model for the fan speed is constructed to obtain the speed demand; The expression of the tracking control model is: Among them, ω r0 is the initial speed of the fan; Δω r H is the speed change required for the fan to meet the inertia requirement. vir Indicates the real-time equivalent inertia time constant of the wind turbine during inertial response, Δf max t vir The frequency deviation value corresponding to the moment.

2. The wind turbine virtual inertia control method based on system inertia requirements according to claim 1, characterized in that: In the process of obtaining the virtual inertia requirement, based on the system minimum inertia requirement, a first expression for representing the system frequency change rate constraint is generated by obtaining the system maximum frequency change rate; Obtaining a second expression for representing an inertia time constant of a system with a high proportion of wind power when the wind turbine provides virtual inertia; The first expression and the second expression are combined to generate a third expression for expressing the virtual inertia requirement.

3. The wind turbine virtual inertia control method based on system inertia requirements according to claim 2, characterized in that: In the process of generating the first expression, the second expression and the third expression, the first expression is: Where ΔP d is the power disturbance; H sys is the system inertia time constant, H min is the minimum inertia requirement of the system, Indicates the rate of change of system frequency; The second expression is: Where H g is the inertia time constant of the synchronous machine; S g is the rated capacity of the synchronous generator; S B is the system rated capacity; k is the wind power penetration rate; H vir is the virtual inertia time constant of the wind turbine; The third expression is:

4. The wind turbine virtual inertia control method based on system inertia requirements according to claim 3, characterized in that: In the process of obtaining the virtual inertia action time of the wind turbine, the frequency response equation of the wind power grid-connected system after being subjected to power disturbance is constructed as follows: Among them, H sys is the system inertia time constant, Δf(t) is the frequency deviation signal, ΔP d is the power disturbance, D sys is the load regulation coefficient, ΔP m is the synchronous machine power response signal, ΔP w is the wind turbine power response signal; The virtual inertia action time is obtained according to the frequency response equation.

5. The wind turbine virtual inertia control method based on system inertia requirements according to claim 4, characterized in that: In the process of constructing the frequency response equation, the system inertia time constant H sys It depends on the capacity ratio of the synchronous machine and is expressed as: H sys =H g (1-k)。 6. The wind turbine virtual inertia control method based on system inertia requirements according to claim 5, characterized in that: In the process of constructing the frequency response equation, the synchronous machine power response signal ΔP m Equivalent to the first-order inertial signal, expressed as: Among them, T g K is the synchronous machine’s primary frequency modulation delay time, sys is the primary frequency modulation coefficient, Δf is the frequency deviation signal, and s is a complex variable; The primary frequency modulation coefficient is expressed as: K sys =K g (1-k) Among them, K g is the primary frequency modulation coefficient of the synchronous machine.

7. The wind turbine virtual inertia control method based on system inertia requirements according to claim 6, characterized in that: In the process of constructing the frequency response equation, the expression of the frequency deviation signal Δf(t) is: in, Derivative Δf(t) to obtain the virtual inertia action time t vir , expressed as:

8. A wind turbine virtual inertia control system based on system inertia requirements, characterized in that: include: a virtual inertia demand generation module, configured to obtain a virtual inertia demand of the wind turbine in the high-wind-power-penetration system according to a system frequency change rate constraint, wherein the system frequency change rate constraint is used to represent a constraint condition of the frequency change rate of the high-wind-power-penetration system; A virtual inertia action time generation module is used to obtain the virtual inertia action time of the wind turbine according to the wind power grid connection standard. The power generation equipment of the wind power grid connection system is composed of a synchronous machine and a wind turbine. The virtual inertia action time is used to represent the time it takes for the wind turbine to complete the inertial response when the frequency drops or rises to the frequency deviation extreme value; The control strategy generating module is used to generate the wind turbine virtual inertia control strategy based on the virtual inertia requirement, in accordance with the wind turbine power response principle, and according to the virtual inertia action time.

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