A method for evaluating fan access scale and related equipment

Abstract

The application relates to the technical field of energy, and discloses a method for evaluating the access scale of a fan and related equipment, which comprises the following steps: constructing a simplified model of primary frequency modulation of a doubly-fed fan based on inertial response control; determining the relationship between the active power of the doubly-fed fan and the system frequency deviation during primary frequency modulation according to the simplified model of primary frequency modulation of the doubly-fed fan; constructing a frequency response model of a full power system containing the doubly-fed fan participating in frequency modulation, thermal power generating units and energy storage devices based on the relationship between the active power of the doubly-fed fan and the system frequency deviation during primary frequency modulation; and evaluating the frequency response model of the full power system to obtain the maximum access scale of the system fan. The maximum access scale of the system fan can be accurately calculated by evaluating the frequency response model of the full power system. This helps to maximize the use of wind energy resources under the premise of not exceeding the frequency modulation capacity of the system, and ensures the reliability and stability of the power system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy, in particular to a method for evaluating the access scale of a wind turbine and related equipment. BACKGROUND

[0002] In order to cope with the global energy crisis, reduce carbon emissions on the power generation side, and accelerate the development and utilization of renewable energy, it has gradually become a social consensus that the penetration rate of renewable energy is steadily increasing. Renewable energy, represented by wind energy, solar energy, geothermal energy, and biomass energy, has the advantages of abundant resources, sustainable utilization, low power generation cost, and clean and efficient operation. Among them, wind power occupies an important position in new energy due to its clean and efficient operation, low operating cost, and short construction period. Large-scale wind turbine grid connection has become the most mature and most promising new energy utilization method.

[0003] Among various types of wind power generation systems, wind power generation systems based on double-fed motors are widely used in global wind farms due to their small size, low cost, and flexible control. However, the connection of large-scale double-fed wind turbines in actual operation has caused many risks. First, since the double-fed wind turbine rotor is connected to the grid through a power electronic converter and has no physical rotating structure, and it uses maximum power tracking control, grid voltage oriented control, and other frequency decoupling control methods during operation, its equivalent inertia is much smaller than that of a synchronous generator, which greatly reduces the equivalent inertia of the power system, leading to intensified system frequency fluctuations. When frequency disturbances occur in power systems with a high proportion of new energy, over / under frequency protection actions are easily triggered, causing new energy generation systems to operate off-grid, which is not conducive to the frequency stability of the power grid. In addition, conventional units are high-quality dynamic and steady-state active regulation means, and after a large number of conventional units are replaced, the transient active power support capacity of double-fed wind turbines is severely insufficient, so the active power supply quality at the power generation side is poor, and the system frequency regulation capability is greatly reduced. Secondly, due to the uncertainty of wind speed, the output fluctuation and operating condition uncertainty of renewable energy are significant, which makes the system frequency regulation change from only having load-side uncertainty to having both generation-side and load-side uncertainty. Traditional power systems generally use the method of reserving sufficient active reserves to ensure frequency stability, but as the installed capacity of renewable energy continues to increase, the demand for system active reserves also continues to increase, which brings new challenges to system frequency stability. Therefore, high-proportion double-fed wind turbine access will cause serious system frequency stability problems. Therefore, how to accurately evaluate the maximum access scale of double-fed wind turbines for power systems has important guiding significance for the operation and planning of power systems.

[0004] Currently, the existing technology still takes the post-disturbance system frequency steady-state deviation as the key indicator for measuring frequency stability. In the research process, the limit access ratio of the wind turbine is often solved only from this single constraint, resulting in poor applicability of the calculated limit access ratio, which still leads to some frequency constraint indicators exceeding the limit in some system operating conditions, thereby bringing hidden dangers to the frequency stability evaluation of the system. However, with the continuous increase of the wind turbine access ratio, the excessively large frequency change rate caused by low inertia will lead to the damage of the internal structure of the unit and the off-grid of the distributed power supply, thereby threatening the safe operation of the generator set. At the same time, the excessively large frequency change rate will make the primary frequency modulation fail to act in time, and the system frequency will be unstable. In addition, the existing research has less consideration on the primary frequency modulation support capability of the wind turbine when evaluating the access scale of the wind turbine, and the influence of the wind turbine access on the whole process of frequency response characteristics is not fully considered, so the maximum access scale of the wind turbine obtained is often not accurate enough. Therefore, the support of the primary frequency modulation capability of the wind turbine to the system frequency needs to be considered comprehensively, and the access scale of the wind turbine needs to be accurately and efficiently evaluated in combination with various frequency stability constraints. SUMMARY

[0005] In order to overcome the defects of the above-mentioned prior art, the purpose of the present application is to provide a wind turbine access scale evaluation method and related equipment to solve the technical problem of the accuracy of the wind turbine access scale evaluation in the prior art.

[0006] The present application is realized by the following technical solutions:

[0007] In a first aspect, the present application provides a wind turbine access scale evaluation method, comprising:

[0008] A simplified model of the primary frequency modulation of the doubly-fed wind turbine based on the inertia response control is constructed, and the relationship between the active power of the doubly-fed wind turbine and the system frequency deviation during the primary frequency modulation is determined according to the simplified model of the primary frequency modulation of the doubly-fed wind turbine.

[0009] A full power system frequency response model containing the doubly-fed wind turbine participating in frequency modulation, thermal power units and energy storage devices is constructed based on the relationship between the active power of the doubly-fed wind turbine and the system frequency deviation during the primary frequency modulation.

[0010] The maximum access scale of the system wind turbine is evaluated by the full power system frequency response model.

[0011] Preferably, in the step of constructing the simplified model of the primary frequency modulation of the doubly-fed wind turbine based on the inertia response control, the expression of the simplified model of the primary frequency modulation of the doubly-fed wind turbine is as follows:

[0012]

[0013] In the formula, is the wind wheel speed; is the mechanical power; is the electrical power; is the inertia time constant of the wind turbine; is the air mass density; is the rotor radius; The wind energy utilization gain is determined by the tip speed ratio and pitch angle Decide; is the wind speed; is the rated power of the doubly-fed converter; is the unloading factor, multiply the maximum active power of the doubly fed wind turbine by , in order to retain a certain amount of spare capacity to participate in primary frequency control; , where is the unloading factor Tip speed ratio at For maximum wind energy utilization gain; is the maximum power point control gain, in which the doubly fed wind turbine adjusts Work at maximum power point; is the system frequency; is the system rated frequency; is the derivative gain that simulates the inertial response of the conventional generator; It is the proportional gain that supports primary frequency modulation in inertia response control.

[0014] Furthermore, in the step of determining the relationship between the active power of the doubly fed wind turbine and the system frequency deviation during the primary frequency regulation period according to the simplified model of the doubly fed wind turbine primary frequency regulation, the specific process is as follows:

[0015] Determine the nonlinear system, the expression is as follows:

[0016]

[0017] Where: and is a nonlinear function; is a state variable; is the input variable; is the output variable;

[0018] The Taylor series expansion is used to expand the nonlinear system to obtain the first-order approximate linear increment at the initial equilibrium point, which is expressed as follows:

[0019]

[0020] Where, ;

[0021] The Laplace transform of the first-order approximate linearized increments gives the transformed nonlinear system, which is expressed as follows:

[0022]

[0023] In the converted nonlinear system, the rotor speed is selected as the state variable , the frequency and the change of the frequency are selected as the input variable , and the active power of the fan is selected as the output variable , and the expression is as follows:

[0024]

[0025] Among them, ; ;

[0026] According to the rotor speed, the frequency and the change of the frequency, and the active power of the fan, the relationship between the active power of the doubly-fed fan and the system frequency deviation during primary frequency modulation is determined, and the expression is as follows:

[0027]

[0028] Among them, is the change of active power; is the system frequency deviation; is the Laplace operator.

[0029] Preferably, in the step of constructing the frequency response model of the full power system containing the doubly-fed fan, thermal power unit and energy storage device participating in frequency modulation based on the relationship between the active power of the doubly-fed fan and the system frequency deviation during primary frequency modulation, the specific process is as follows:

[0030] Determine the primary frequency modulation model of the full power system, and the expression is as follows:

[0031]

[0032] In the formula, is the capacity proportion of the doubly-fed fan, is the system inertia time constant, is the system damping, is the change of active power of the conventional generator, is the change of energy storage output, is the unbalanced power caused by disturbance; is the mechanical power gain coefficient, is the reheater time constant of the steam turbine, is the high-pressure cylinder gain, is the frequency deviation coefficient of the synchronous generator;

[0033] According to the primary frequency modulation model of the full power system, the frequency is adjusted, and the energy storage frequency is determined by the product of the first-order lag and the proportional gain during frequency adjustment, and the expression of the energy storage frequency is as follows:

[0034]

[0035] wherein, is the energy storage battery control gain, is the control time delay;

[0036] The full power system frequency response model is constructed according to the energy storage frequency, and the expression is as follows:

[0037] .

[0038] Preferably, in the step of evaluating the maximum access scale of the system wind turbine according to the full power system frequency response model, the limit access proportion of the wind turbine is derived through the constraints of the frequency change rate and the steady-state frequency deviation, and the maximum access scale of the system wind turbine is evaluated through the limit access proportion of the wind turbine.

[0039] Further, in the process of deriving the limit access proportion of the wind turbine through the constraints of the frequency change rate and the steady-state frequency deviation, when the maximum frequency change rate of the system is taken as , the expression of the maximum wind turbine access scale of the system with the maximum frequency change rate is as follows:

[0040]

[0041] wherein, is the maximum wind turbine access scale of the system considering the maximum frequency change rate limit;

[0042] When the maximum steady-state frequency deviation of the system is taken as , the expression of the maximum wind turbine access scale of the system with the maximum steady-state frequency deviation is as follows:

[0043]

[0044] wherein, is the maximum wind turbine access scale of the system considering the maximum steady-state frequency deviation limit.

[0045] Further, in the process of evaluating the maximum access scale of the system wind turbine through the limit access proportion of the wind turbine, the minimum value of the maximum wind turbine access scale under the constraints of the frequency change rate and the steady-state frequency deviation is set as the maximum access scale of the wind turbine, and the expression is as follows:

[0046]

[0047] wherein, is the maximum wind turbine access scale of the system considering the maximum frequency change rate limit and the maximum steady-state frequency deviation limit.

[0048] In a second aspect, the present application further provides a wind turbine access scale evaluation system, comprising:

[0049] A model processing module is configured to construct a simplified model of primary frequency modulation of a doubly-fed wind turbine based on inertia response control, and determine the relationship between active power of the doubly-fed wind turbine and system frequency deviation during primary frequency modulation according to the simplified model of primary frequency modulation of the doubly-fed wind turbine.

[0050] A model construction module is configured to construct a full power system frequency response model containing the doubly-fed wind turbine, thermal power unit and energy storage device participating in frequency modulation based on the relationship between active power of the doubly-fed wind turbine and system frequency deviation during primary frequency modulation.

[0051] An evaluation module is configured to evaluate the full power system frequency response model to obtain the maximum access scale of system wind turbine.

[0052] In a third aspect, the present application further provides a mobile terminal, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the wind turbine access scale evaluation method as described above when executing the computer program.

[0053] In a fourth aspect, the present application further provides a computer readable storage medium, which stores a computer program, wherein the computer program is executable by a processor to implement the steps of the wind turbine access scale evaluation method as described above.

[0054] Compared with the prior art, the present application has the following beneficial technical effects:

[0055] The present application provides a wind turbine access scale evaluation method, which can more accurately describe the dynamic behavior of a doubly-fed wind turbine during primary frequency modulation of a power system by constructing a simplified model of primary frequency modulation of the doubly-fed wind turbine based on inertia response control. This helps to improve the response speed and regulation capacity of the power system during frequency fluctuations, ensuring stable operation of the power system. By constructing a full power system frequency response model containing a doubly-fed wind turbine, a thermal power unit and an energy storage device, the characteristics and advantages of various frequency modulation resources can be considered comprehensively. This helps to realize the optimal configuration of frequency modulation resources, improve resource utilization efficiency, and reduce the operating cost of the power system. By evaluating the full power system frequency response model, the maximum access scale of system wind turbine can be accurately calculated. This helps to maximize the use of wind energy resources while ensuring the reliability and stability of the power system without exceeding the system frequency modulation capacity.

[0056] Furthermore, the participation of doubly-fed wind turbines in system primary frequency regulation can increase the maximum wind turbine access scale. This paper takes into account wind turbine inertial response control and establishes a simplified model for doubly-fed wind turbine primary frequency regulation, providing a theoretical basis for assessing the maximum wind turbine access scale. In scenarios with a high proportion of renewable energy access, this paper considers the impact of energy storage devices connected to the power system on the system's frequency regulation capabilities. While ensuring system frequency stability, this paper establishes a more comprehensive system frequency response model to accurately assess the maximum wind turbine access scale.

[0057] Furthermore, based on the full system frequency response model, the present invention comprehensively considers multiple frequency stability constraints such as system frequency variation and steady-state frequency deviation, and can accurately deduce the maximum access scale of wind turbines in the power system, thereby better maintaining system frequency stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Flowchart of a method for evaluating wind turbine access scale according to an embodiment of the present invention;

[0059] Figure 2 Schematic diagram of the structure of the doubly-fed wind turbine IRC in an embodiment of the present invention;

[0060] Figure 3 This is the primary frequency modulation model of the system in the embodiment of the present invention;

[0061] Figure 4 Schematic diagram of energy storage frequency modulation transfer function in an embodiment of the present invention;

[0062] Figure 5 Schematic diagram of frequency variation and steady-state frequency deviation in an embodiment of the present invention;

[0063] Figure 6 This is a structural diagram of a test system in an embodiment of the present invention;

[0064] Figure 7 In the embodiment of the present invention, The frequency response curve diagram below;

[0065] Figure 8 In the embodiment of the present invention, The frequency response curve diagram below;

[0066] Figure 9 This is a schematic diagram of the wind turbine access scale in an embodiment of the present invention;

[0067] In the figure: 1. Model processing module; 2. Model building module; 3. Evaluation module. DETAILED DESCRIPTION

[0068] In order to make the person skilled in the art better understand the technical scheme of the present application, the technical scheme in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.

[0069] The present application will be further described in detail below in conjunction with the drawings:

[0070] The inertia of the power system describes the amount of kinetic energy released or absorbed by the rotating elements to compensate for unbalanced power. The output power of the doubly-fed wind turbine is determined by the maximum power point tracking control (MPPT), which depends on the wind speed and is decoupled from the system frequency, so it does not have the ability to respond to inertia. However, by applying appropriate additional control to the doubly-fed wind turbine, its rotating elements can still release or absorb kinetic energy when the system frequency changes to achieve a simulated inertia response, i.e. IRC. Currently, there are two methods to achieve IRC for doubly-fed wind turbines, one is to simulate inertia response by modifying the maximum power tracking curve, and the other is to feedback the system frequency fluctuation through a proportional derivative (PD) controller. The output of the controller is superimposed on the active power reference value given by MPPT. In the PD type inertia response controller, differential control is used to simulate inertia response, and proportional control essentially simulates first frequency modulation. Unlike the first frequency modulation of traditional generators, the doubly-fed wind turbine is always running in MPPT mode. The energy source for first frequency modulation is not the mechanical power input by the governor, but the kinetic energy of the wind turbine, so the first frequency modulation of the doubly-fed wind turbine is temporary. The purpose of the present application is to provide a method for evaluating the scale of wind turbine access and related equipment to solve the technical problem of the accuracy of the evaluation of the scale of wind turbine access in the prior art, according to Figure 2 The structure of the IRC is shown in FIG. 1, wherein is the system frequency, is the system rated frequency, is the wind speed, and the wind speed depends on the active power reference value of MPPT . is the derivative gain for simulating the inertia response of the traditional generator, is the proportional gain for supporting first frequency modulation in the inertia response control. The mathematical formula model is as follows:

[0071] (1)

[0072] Referring to Figure 1The present invention provides a method for evaluating the scale of wind turbine access, comprising:

[0073] Step 1: construct a simplified primary frequency regulation model of a doubly fed wind turbine based on inertial response control, and determine the relationship between the active power of the doubly fed wind turbine and the system frequency deviation during the primary frequency regulation period according to the simplified primary frequency regulation model of the doubly fed wind turbine;

[0074] The doubly-fed wind turbine model in this invention primarily consists of a wind turbine generator, a drive shaft, a doubly-fed asynchronous generator, a back-to-back converter, and its control system. Eigenvalue analysis of the full-system model reveals that hidden roots near the rotor speed are close to the imaginary axis, while other hidden roots are far away. When the frequency fluctuates, only the variables related to the rotor speed play a dominant role.

[0075] Specifically, in the step of constructing a simplified primary frequency regulation model of a doubly fed wind turbine based on inertial response control, the expression of the simplified primary frequency regulation model of the doubly fed wind turbine is as follows:

[0076] (2)

[0077] Where, is the wind wheel speed; is the mechanical power; is the electrical power; is the inertia time constant of the wind turbine; is the air mass density; is the rotor radius; The wind energy utilization gain is determined by the tip speed ratio and pitch angle Decide; is the rated power of the doubly-fed converter; is the unloading factor, multiply the maximum active power of the doubly fed wind turbine by , in order to retain a certain amount of spare capacity to participate in primary frequency control; , where is the unloading factor Tip speed ratio at is the maximum power point control gain, in which the doubly fed wind turbine adjusts Work at maximum power point.

[0078] Among them, in the step of determining the relationship between the active power of the doubly fed wind turbine and the system frequency deviation during the primary frequency regulation period according to the simplified model of the doubly fed wind turbine primary frequency regulation, the specific process is as follows:

[0079] Determine the nonlinear system, the expression is as follows:

[0080] (3)

[0081] Where: and is a nonlinear function; is a state variable; is an input variable; is an output variable;

[0082] The first-order approximate linearization increment of the nonlinear system at the initial equilibrium point is obtained by using Taylor series expansion, and the expression is as follows:

[0083] (4)

[0084] In the formula, ;

[0085] The Laplace transform is performed on the first-order approximate linearization increment to obtain the converted nonlinear system, and the expression is as follows:

[0086] (5)

[0087] In the converted nonlinear system, the rotor speed is selected as the state variable , the frequency and the change amount of the frequency are selected as the input variable , and the active power of the fan is selected as the output variable , and the expression is as follows:

[0088] (6)

[0089] In the formula, ; ;

[0090] According to the rotor speed, the frequency and the change amount of the frequency, and the active power of the fan, the relationship between the active power of the doubly-fed fan and the system frequency deviation during primary frequency modulation is determined, and the expression is as follows:

[0091] (7)

[0092] In the formula, is the change amount of the active power; is the system frequency deviation; is the Laplace operator.

[0093] Step 2, based on the relationship between the active power of the doubly-fed fan and the system frequency deviation during primary frequency modulation, a full power system frequency response model containing the doubly-fed fan participating in frequency modulation, thermal power generating units and energy storage devices is constructed;

[0094] Specifically, based on the relationship between the active power of the doubly-fed wind turbine and the frequency deviation of the system during primary frequency modulation, the steps of constructing the frequency response model of the full power system including the doubly-fed wind turbine, thermal power unit and energy storage device are obtained. Considering the frequency response equation of the power system with large-scale grid-connected doubly-fed wind turbines, when analyzing the frequency stability of the system, only the balance of the active power of the whole system is considered, and the active power distribution characteristics are not considered. The primary frequency modulation model of the system is as shown in the following formula (1), and the specific process is as follows: Figure 3

[0095] The primary frequency modulation model of the full power system is determined, and the expression is as follows:

[0096] (8)

[0097] In the formula: is the capacity proportion of the doubly-fed wind turbine, is the system inertia time constant, is the system damping, is the active power change of the conventional generator, is the energy storage output change, is the unbalanced power caused by the disturbance. is the mechanical power gain coefficient, is the reheater time constant of the steam turbine, is the high-pressure cylinder gain, is the frequency deviation coefficient of the synchronous generator;

[0098] According to the primary frequency modulation model of the full power system, the frequency regulation is carried out, and the characteristics during the frequency regulation are determined by the product of the first-order lag and the proportional gain to obtain the energy storage frequency, as shown in the following formula (2), and the expression of the energy storage frequency is as follows: Figure 4

[0099] (9)

[0100] In the formula: is the energy storage battery control gain, is the control time delay;

[0101] According to the energy storage frequency, the frequency response model of the full power system is constructed, and the expression is as follows:

[0102] (10)

[0103] Step 3, the maximum access scale of the system wind turbine is obtained by evaluating the full power system frequency response model.

[0104] ​​Specifically, in the step of evaluating the maximum wind turbine access scale of the whole power system frequency response model, the wind turbine limit access proportion is derived through the constraints of the frequency change rate and the steady-state frequency deviation, and the maximum wind turbine access scale of the system is evaluated through the wind turbine limit access proportion.

[0105] The frequency change rate and the steady-state frequency deviation limit the frequency fluctuation at the initial and final stages of the disturbance, respectively. Figure 5

[0106] The frequency change amount in the application is a key index for measuring the frequency transient stability of the power system after suffering from the disturbance. At the initial stage of the disturbance, the system stability control measures such as the generator speed regulation system are not started due to the existence of the frequency modulation dead zone, the load size is proportional to the frequency, and the load is also in the maximum power state, and only the system inertia level plays a role, at this time, the RoCoF is maximum. When calculating, the RoCoF at the moment of the disturbance can be directly taken as one of the indexes for characterizing the frequency transient stability of the system.

[0107] In the process of deriving the wind turbine limit access proportion through the constraints of the frequency change rate and the steady-state frequency deviation, when the system suffers from a power step disturbance with a size of , that is, , according to the Laplace initial value theorem, the following relationship can be obtained:

[0108] (11)

[0109] When the maximum frequency change rate of the system is taken as , the expression of the maximum wind turbine access scale of the system with the maximum frequency change rate is as follows:

[0110] (12)

[0111] Wherein, is the maximum wind turbine access scale of the system considering the frequency change rate limit.

[0112] The steady-state frequency deviation in the application is the deviation between the frequency of the system after suffering from the disturbance and returning to the equilibrium state and the frequency before the disturbance, which directly reflects the strength of the primary frequency modulation capacity of the system. When the system suffers from a power step disturbance with a size of , that is, , according to the Laplace final value theorem, the following relationship can be obtained:

[0113] (13)

[0114] When the maximum steady-state frequency deviation of the system is taken as , the expression of the maximum wind turbine access scale of the system with the maximum steady-state frequency deviation is as follows:

[0115] ​ (14)

[0116] wherein, is the maximum wind turbine access scale of the system considering the maximum steady-state frequency deviation limit.

[0117] wherein, in the process of evaluating the maximum wind turbine access scale of the system by the wind turbine limit access ratio, the minimum value of the maximum wind turbine access scale under the constraints of the frequency change rate and the steady-state frequency deviation is set as the maximum wind turbine access scale, and the expression is as follows:

[0118] (15)

[0119] wherein, is the maximum wind turbine access scale of the system considering the maximum frequency change rate limit and the maximum steady-state frequency deviation limit.

[0120] Embodiment 1

[0121] The structure of the test system is shown in Figure 6 , which is modified on the basis of the IEEE-9 node system, and a 150 MW wind farm and a 50 MW energy storage system are added at Bus3. In order to simplify the analysis, the wind farm is composed of a plurality of double-fed wind turbines with consistent parameters, and the rated power of a single double-fed wind turbine is 1.5 MW, and the remaining parameters are based on the DFIG detailed model in MATLAB / Simulink R2020a. In order to make the double-fed wind turbine work in the maximum power tracking area, the wind speed is 9 m / s at steady state, the load shedding level D=0.1, the limits of RoCoF and SFD are selected as 0.05 Hz / s and 0.2 Hz respectively, the frequency modulation gain of the energy storage is 0.1, and the disturbance is set at Bus5.

[0122] The embodiment provides an evaluation method for wind turbine access scale, and the specific process is as follows:

[0123] Firstly, a simplified model of primary frequency regulation of double-fed wind turbine considering inertia response control is built.

[0124] The relationship between the active power of the double-fed wind turbine and the system frequency deviation during primary frequency regulation is as follows:

[0125] (16)

[0126] Secondly, a frequency response model of the whole power system containing double-fed wind turbines participating in frequency regulation, traditional thermal power units and energy storage devices is established.

[0127] The expression of the whole system frequency response is as follows:

[0128] (17)

[0129] Finally, based on the above full-system frequency response model, considering the constraints of frequency change rate RoCoF and steady-state frequency deviation SFD, the wind turbine limit access ratio is derived, and the maximum access scale of the system wind turbine is determined.

[0130] When the maximum frequency change rate of the system is , the maximum wind turbine access scale of the system considering the maximum frequency change rate is:

[0131] (18)

[0132] When the maximum steady-state frequency deviation of the system is , the maximum wind turbine access scale of the system considering the maximum steady-state frequency deviation is:

[0133] (19)

[0134] Considering the above two constraints, take the minimum value of the two as the maximum access scale of the wind turbine:

[0135] (20)

[0136] Specifically, set the scene as follows:

[0137] Scenario one: keep the proportional gain constant and the derivative gain constant in the inertia response control unchanged, adjust the load disturbance, and observe the system frequency dynamics. Specifically, , . Change the load disturbance to 8%, 10% and 12% respectively.

[0138] Scenario two: keep the proportional gain constant and the load disturbance in the inertia response control unchanged, adjust the derivative gain constant, and observe the system frequency dynamics. Specifically, set the load disturbance to 10% of the system load. , to 0, 5 and 10 respectively.

[0139] In scenario one, according to formulas (18)-(20), the are 22.07%, 21.56% and 19.58% respectively. Set the number of double-fed wind turbines to 67, 65 and 62 respectively, and record the frequency response of the system under disturbance. From Figure 7 , it can be seen that under different , SFD is about 0.2 Hz, and RoCoF is less than 0.05 Hz / s. The time domain simulation results prove the effectiveness of the proposed model. Considering the constraints of RoCoF and SFD, the larger the load disturbance scale is, the smaller the is, as shown in Table 1.

[0140] Table 1 Kmax calculation results under different scenarios

[0141]

[0142] In scenario 2, we can get The frequency responses of the system under disturbance are recorded. Figure 8 It can be seen that the SFD is near the boundary and the RoCoF is within 0.05Hz / s. The increase, It also gradually increases, that is, the frequency support capability of the doubly fed wind turbine is enhanced.

[0143] These results demonstrate that the inclusion of a doubly-fed wind turbine in the primary frequency regulation of the system can improve RoCoF and SFD. The main factors influencing frequency stability are the load variation level, the wind turbine frequency response control parameters, the system inertia constant, and the energy storage frequency regulation coefficient. Time-domain simulations validate the effectiveness of the proposed simplified model.

[0144] In summary, the present invention provides a method for evaluating the access scale of wind turbines. By constructing a simplified model of primary frequency regulation of doubly fed wind turbines based on inertial response control, the dynamic behavior of doubly fed wind turbines in the primary frequency regulation process of the power system can be more accurately described. This helps to improve the response speed and regulation capability of the power system during frequency fluctuations, and ensure the stable operation of the power system. By constructing a frequency response model of the entire power system including doubly fed wind turbines, thermal power units and energy storage devices, the characteristics and advantages of various frequency regulation resources can be comprehensively considered. This helps to achieve the optimal configuration of frequency regulation resources, improve resource utilization efficiency and reduce the operating cost of the power system. By evaluating the frequency response model of the entire power system, the maximum access scale of the system wind turbines can be accurately calculated. This helps to ensure that wind energy resources are maximized without exceeding the frequency regulation capability of the system, while ensuring the reliability and stability of the power system.

[0145] Example 2

[0146] according to Figure 9 As shown, the present invention also provides a wind turbine access scale evaluation system, comprising:

[0147] Model processing module 1 is used to construct a simplified model of primary frequency regulation of a doubly fed wind turbine based on inertial response control, and determine the relationship between the active power of the doubly fed wind turbine and the system frequency deviation during the primary frequency regulation period according to the simplified model of the doubly fed wind turbine primary frequency regulation;

[0148] A model construction module 2 is configured to construct a full power system frequency response model containing the doubly-fed wind turbine, thermal power unit and energy storage device participating in frequency modulation based on the relationship between the active power of the doubly-fed wind turbine and the system frequency deviation during primary frequency modulation.

[0149] An evaluation module 3 is configured to evaluate the full power system frequency response model to obtain the maximum access scale of the system wind turbine.

[0150] Embodiment 3

[0151] The application further provides a mobile terminal comprising a memory, a processor, and a computer program, such as a wind turbine access scale evaluation program, stored in the memory and executable on the processor.

[0152] The processor implements the steps of the wind turbine access scale evaluation method when executing the computer program, for example:

[0153] A doubly-fed wind turbine primary frequency modulation simplified model based on inertia response control is constructed, and the relationship between the active power of the doubly-fed wind turbine and the system frequency deviation during primary frequency modulation is determined according to the doubly-fed wind turbine primary frequency modulation simplified model;

[0154] A full power system frequency response model containing the doubly-fed wind turbine, thermal power unit and energy storage device participating in frequency modulation is constructed based on the relationship between the active power of the doubly-fed wind turbine and the system frequency deviation during primary frequency modulation;

[0155] The maximum access scale of the system wind turbine is obtained by evaluating the full power system frequency response model.

[0156] Alternatively, the processor implements the functions of the modules in the system when executing the computer program, for example:

[0157] A model processing module 1 is configured to construct a doubly-fed wind turbine primary frequency modulation simplified model based on inertia response control, and determine the relationship between the active power of the doubly-fed wind turbine and the system frequency deviation during primary frequency modulation according to the doubly-fed wind turbine primary frequency modulation simplified model;

[0158] A model construction module 2 is configured to construct a full power system frequency response model containing the doubly-fed wind turbine, thermal power unit and energy storage device participating in frequency modulation based on the relationship between the active power of the doubly-fed wind turbine and the system frequency deviation during primary frequency modulation;

[0159] An evaluation module 3 is configured to evaluate the full power system frequency response model to obtain the maximum access scale of the system wind turbine.

[0160] For example, the computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present application. The one or more modules / units can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program in the mobile terminal.

[0161] For example, the computer program can be divided into a model processing module 1, a model building module 2, and an evaluation module 3.

[0162] The specific functions of each module are as follows:

[0163] The model processing module 1 is used to build a simplified model of primary frequency modulation of a doubly-fed wind turbine based on inertial response control, and to determine the relationship between the active power of the doubly-fed wind turbine and the system frequency deviation during primary frequency modulation according to the simplified model of primary frequency modulation of the doubly-fed wind turbine.

[0164] The model building module 2 is used to build a frequency response model of the whole power system containing the doubly-fed wind turbine, thermal power unit and energy storage device participating in frequency modulation based on the relationship between the active power of the doubly-fed wind turbine and the system frequency deviation during primary frequency modulation.

[0165] The evaluation module 3 is used to evaluate the maximum access scale of the system wind turbine based on the frequency response model of the whole power system.

[0166] The mobile terminal can be a desktop computer, a notebook, a palm computer, a cloud server and other computing devices. The mobile terminal can include, but is not limited to, a processor and a memory.

[0167] The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc. The processor is the control center of the mobile terminal, which connects all parts of the mobile terminal through various interfaces and lines.

[0168] The memory can be configured to store the computer programs and / or modules, and the processor can realize various functions of the mobile terminal by running or executing the computer programs and / or modules stored in the memory and calling data stored in the memory.

[0169] The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application program required by a function (such as a sound playing function, an image playing function, etc.), and the like; and the data storage area can store data created according to use of the mobile phone (such as audio data, a phone book, etc.), and the like. In addition, the memory can include a high-speed random access memory, and can also include a nonvolatile memory, such as a hard disk, a memory, a plug-in hard disk, a SmartMediaCard (SMC), a Secure Digital (SD) card, a Flash Card, at least one disk storage device, a flash memory device, or other volatile solid-state memory device.

[0170] Embodiment 4

[0171] The application further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the fan access scale evaluation method.

[0172] The modules / units integrated in the mobile terminal can be stored in a computer readable storage medium if they are realized in the form of software function units and sold or used as independent products.

[0173] Based on such understanding, the application realizes all or part of the processes in the above method, and can also be completed by a computer program instructing related hardware, the computer program can be stored in a computer readable storage medium, and the computer program can realize the steps of the above aggregated reinforcement learning resource scheduling method when executed by a processor. The computer program includes computer program codes, and the computer program codes can be in the form of source codes, object codes, executable files or some intermediate forms, etc.

[0174] The computer readable medium can include any entity or device, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier wave signal, telecommunication signal, software distribution medium, etc. that can carry the computer program codes.

[0175] Note that the computer readable medium can include appropriate modifications to the content according to the requirements of legislation and patent practice in a jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunication signals.

[0176] Finally, it should be noted that the above embodiments are merely intended to illustrate, but not to limit the technical solutions of the present application, and although the present application has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered within the protection scope of the claims of the present application.

Claims

1. A method for evaluating the scale of wind turbine access, characterized in that: include: A simplified model of primary frequency regulation of a doubly fed wind turbine based on inertial response control is constructed. The relationship between the active power of the doubly fed wind turbine and the system frequency deviation during the primary frequency regulation period is determined based on the simplified model. Based on the relationship between the active power of the doubly fed wind turbine and the system frequency deviation during the primary frequency regulation period, a full power system frequency response model including the doubly fed wind turbine, thermal power units and energy storage devices participating in the frequency regulation is constructed. The frequency response model of the entire power system is evaluated to obtain the maximum wind turbine connection scale of the system; The specific process of constructing a frequency response model of the entire power system including the doubly-fed wind turbines, thermal power units, and energy storage devices participating in frequency regulation based on the relationship between the active power of the doubly-fed wind turbines and the system frequency deviation during the primary frequency regulation period is as follows: Determine the primary frequency regulation model of the entire power system, and the expression is as follows: 2(1-K)H sys Δfs=(1-K)ΔP G +KΔP e +ΔP ess +ΔP d -DΔf Where: K is the proportion of the access capacity of the double-fed wind turbine, H sys is the system inertia time constant, D is the system damping, ΔP G is the active power variation of conventional generator, ΔP ess is the change in energy storage output, ΔP d is the unbalanced power caused by the disturbance; K mg is the mechanical power gain coefficient, T R is the turbine reheater time constant, F H is the high pressure cylinder gain, K g is the frequency deviation coefficient of the synchronous generator; ΔP e is the change in active power; Δf is the system frequency deviation; s is the Laplace operator; Frequency regulation is performed according to the primary frequency regulation model of the entire power system, and the characteristics of the frequency regulation are determined by multiplying the first-order lag and the proportional gain to obtain the energy storage frequency. The expression of the energy storage frequency is as follows: Among them, K ess is the energy storage battery control gain, T ess To control delay; The frequency response model of the entire power system is constructed based on the energy storage frequency, and the expression is as follows: Among them, H wind is the inertia time constant of the wind turbine; ω r is the wind wheel speed; k d is the derivative gain simulating the inertial response of the traditional generator; k p It is the proportional gain that supports primary frequency modulation in inertia response control; In the step of evaluating the full power system frequency response model to obtain the maximum wind turbine access scale of the system, the wind turbine limit access ratio is derived by the constraints of the frequency change rate and the steady-state frequency deviation, and the maximum wind turbine access scale of the system is obtained by evaluating the wind turbine limit access ratio; In the process of deriving the maximum wind turbine access ratio through the constraints of the frequency change rate and the steady-state frequency deviation, when the maximum frequency change rate of the system is taken as δ, the expression of the maximum wind turbine access scale of the system with the maximum frequency change rate is as follows: Among them, K max,RoCoF The maximum wind turbine connection scale of the system considering the maximum frequency change rate limit; When the maximum steady-state frequency deviation of the system is taken as ε, the expression of the maximum wind turbine connection scale of the system with the maximum steady-state frequency deviation is as follows: Among them, K max,SFD It is the maximum wind turbine connection scale of the system considering the maximum steady-state frequency deviation limit.

2. The method for evaluating the scale of wind turbine access according to claim 1, characterized in that: In the step of constructing a simplified primary frequency regulation model of a doubly fed wind turbine based on inertial response control, the expression of the simplified primary frequency regulation model of the doubly fed wind turbine is as follows: Where, ω r is the wind wheel speed; P m is the mechanical power; P e is the electrical power; H wind is the inertia time constant of the wind turbine; ρ is the air mass density; R is the rotor radius; C p The wind energy utilization gain is determined by the tip speed ratio and pitch angle β; V w is wind speed; P n is the rated power of the doubly fed converter; d is the load shedding factor, which is the maximum active power of the doubly fed wind turbine multiplied by (1-d) to reserve a certain amount of spare capacity for primary frequency control; Where λ0 is the tip speed ratio when the unloading coefficient is d, C pmax is the maximum wind energy utilization gain; k opt is the maximum power point control gain, where the doubly fed wind turbine adjusts ω r Working at the maximum power point; f is the system frequency; f ref is the system rated frequency; k d is the derivative gain simulating the inertial response of the traditional generator; k p It is the proportional gain that supports primary frequency modulation in inertia response control.

3. The method for evaluating the scale of wind turbine access according to claim 2, characterized in that: In the step of determining the relationship between the active power of the doubly-fed wind turbine and the system frequency deviation during the primary frequency regulation period according to the simplified model of the doubly-fed wind turbine primary frequency regulation, the specific process is as follows: Determine the nonlinear system, the expression is as follows: Y=h(X,U) Where: g and h are nonlinear functions; X is the state variable; Y is the output variable; U is the input variable; The Taylor series expansion is used to expand the nonlinear system to obtain the first-order approximate linear increment at the initial equilibrium point, which is expressed as follows: ΔY=CΔX+DΔU Where, The Laplace transform of the first-order approximate linearized increments gives the transformed nonlinear system, which is expressed as follows: ΔY=[C(sI-A) -1 B+D]ΔU In the converted nonlinear system, the rotor speed is selected as the state variable X = [ω r ], the frequency and the change of frequency are input variables The active power of the fan is the output variable Y=[P e ], the expression is as follows: A=[(k m -k e ) / 2H wind ω r ] B=[k p / 2H wind ω r ,k d / 2H wind ω r ] C=[k e ] D=[-k p ,-k d ] in, The relationship between the active power of the doubly fed wind turbine and the system frequency deviation during the primary frequency modulation period is determined based on the rotor speed, frequency, frequency variation, and wind turbine active power. The expression is as follows: Where ΔP e is the change in active power; Δf is the system frequency deviation; s is the Laplace operator.

4. The method for evaluating the scale of wind turbine access according to claim 1, characterized in that: In the process of obtaining the maximum wind turbine access scale of the system through the wind turbine limit access ratio evaluation, the minimum value of the maximum wind turbine access scale under the constraints of the frequency change rate and the steady-state frequency deviation is set as the maximum wind turbine access scale. The expression is as follows: K max =min(K max,RoCoF ,K max,SFD ) Among them, K max It is the maximum wind turbine access scale of the system that comprehensively considers the maximum frequency change rate limit and the maximum steady-state frequency deviation limit.

5. A wind turbine access scale assessment system, based on a wind turbine access scale assessment method according to any one of claims 1 to 4, characterized in that: include: A model processing module is used to construct a simplified primary frequency regulation model of a doubly fed wind turbine based on inertial response control, and to determine the relationship between the active power of the doubly fed wind turbine and the system frequency deviation during the primary frequency regulation period according to the simplified primary frequency regulation model of the doubly fed wind turbine; A model building module is used to construct a full power system frequency response model including doubly fed wind turbines, thermal power units and energy storage devices participating in frequency regulation based on the relationship between the active power of the doubly fed wind turbines and the system frequency deviation during the primary frequency regulation period; The evaluation module is used to evaluate the frequency response model of the entire power system and obtain the maximum access scale of the system wind turbines.

6. A mobile terminal comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method for evaluating the wind turbine access scale according to any one of claims 1 to 4 are implemented.

7. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for evaluating the wind turbine access scale according to any one of claims 1 to 4 are implemented.

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