Inertia demand-based wind turbine generator frequency modulation control method

Abstract

The invention discloses a wind turbine generator frequency modulation control method based on inertia requirements. The method comprises the following steps: analyzing main factors influencing system frequency response characteristics; according to an analysis result, taking the frequency change rate as a constraint, and carrying out system minimum inertia demand evaluation; according to an analysis result, performing system minimum inertia demand evaluation by taking the maximum frequency offset as a constraint; the maximum value of the two constraints is adopted as the minimum inertia demand of the system, so that the sufficient inertia of the system is ensured, and the frequency stability of the system is improved; and constructing a target function according to the results to obtain the output power of the wind turbine generator, and participating in system frequency modulation. In order to solve the problems that the existing comprehensive inertia simulation synchronous machine control is insufficient and the consideration factors of the system minimum inertia evaluation are not comprehensive, a wind turbine generator rotor kinetic energy optimal frequency output power control scheme based on the system minimum inertia demand is provided, and the flexibility and plasticity of the wind turbine generator converter control output power are fully exerted. And the system frequency stability is enhanced.

Description

Technical Field

[0001] This invention relates to a wind-storage frequency regulation control method, and more particularly to a wind turbine frequency regulation control method based on inertia requirements, belonging to the technical field of hybrid energy storage systems. Background Technology

[0002] In recent years, my country's new power system construction has accelerated, and the installed capacity of power sources has continued to expand. With the advancement of wind power generation technology, more and more large-scale wind farms have been connected to the grid. The proportion of double-fed induction generator (DFIG) capacity in the system has increased, while the proportion of traditional synchronous motors has relatively decreased, which has become a trend in the future development of the power system. Because DFIGs widely use variable-speed constant-frequency wind turbine units, they need to be connected to the grid through power electronic devices and typically operate in maximum power point tracking mode. Active power and frequency are decoupled, making it impossible to provide active reserve power to support grid frequency control. They also lack inertial support and primary frequency regulation capabilities. Currently, the method used is to add a frequency control loop to the rotor-side controller of the DFIG to simulate the inertial response and primary frequency regulation characteristics of a synchronous machine, releasing its own rotor kinetic energy to provide frequency support for the disturbed system. However, this method also has shortcomings in comprehensively simulating synchronous machine control and incomplete consideration of factors in the system's minimum inertia assessment. Therefore, it is urgent to solve these problems and deficiencies. Summary of the Invention

[0003] To address the problems and shortcomings of the existing technology, this invention provides a wind turbine frequency regulation control method based on inertia requirements, aiming at virtual inertia control and primary frequency regulation control of the wind turbine. The technical solution adopted by this invention to achieve the above objectives is as follows:

[0004] The frequency regulation control method for wind turbines based on inertia demand includes the following steps: A. Analyze the main factors affecting the frequency response characteristics of the system;

[0005] B. Based on the analysis results, the rate of change of frequency is used as a constraint to evaluate the minimum inertia requirement of the system;

[0006] C. Based on the analysis results, the maximum frequency offset is used as a constraint to evaluate the minimum inertia requirement of the system;

[0007] D. Use the maximum value of the above two constraints as the minimum inertia requirement of the system to ensure sufficient inertia and improve the frequency stability of the system; using the maximum value of the above two constraints as the minimum inertia requirement of the system means using the maximum value of the frequency change rate and the maximum frequency offset constraints in steps B and C as the minimum inertia requirement of the system, as expressed below:

[0008] (1);

[0009] E. Based on the above results, construct an objective function to obtain the output power of the wind turbine, which will then participate in system frequency regulation; further, the output power of the wind turbine, obtained in step E, is expressed as follows:

[0010] (2);

[0011] In the formula, k p The output power coefficient is as follows:

[0012] (3);

[0013] Where, ω off This refers to the fan speed when frequency regulation is discontinued;

[0014] In the formula, P 0 This represents the initial output power of the wind turbine. P m This represents the maximum output power of the wind turbine. ω 0 represents the initial speed of the wind turbine, t off To exit FM time, P f For frequency modulation power, P off To exit FM power, It can be described as t off Approximate linear function, i.e.

[0015] P off =P f +k f (t) off -t on (4);

[0016] in, t on This is the start time of frequency regulation for the wind turbine.

[0017] (5); In the formula, K f This is the frequency modulation power withdrawal coefficient. K MPPT The maximum power point tracking coefficient, Hw Let be the inertial constant of the wind turbine.

[0018] Furthermore, by analyzing the main factors affecting the system's frequency response characteristics as described in step A, the system's frequency dynamic equation can be obtained, as shown in the following expression:

[0019] (6);

[0020] In the formula, Δf is the system frequency deviation, t is time, and Δ P G Δ represents the change in output power of the synchronous generator set. P W Δ represents the change in the output power of the wind turbine. P L S is the load power change, S is the system inertia, Hs is the system inertia constant, ΔP is the disturbance power, Hs is a named value, and the rest are per-unit values.

[0021] Furthermore, step B involves using the rate of change of frequency as a constraint to assess the minimum inertia requirement of the system, expressed as follows:

[0022] (7);

[0023] In the formula, t0 is the initial time of the disturbance, and H min Let F be the minimum inertia of the system, ΔP be the disturbance power, and F be the inertia of the system. max This represents the maximum rate of change of the system frequency.

[0024] Furthermore, the H min To determine the minimum inertia of the system, when considering the influence of induced loads, the disturbance power needs to be corrected to remove the static voltage equivalent inertia of the induced load. The expression is as follows:

[0025] (8);

[0026] In the formula, ΔP U It can be represented as:

[0027] (9);

[0028] In the formula, Δ Pu This is the correction amount for the disturbance power in response to the static voltage response of the induced load. P L0 Let U be the total active load of the system before the disturbance, U0 be the initial voltage before the disturbance, U be the voltage at the moment of the disturbance, and k be the voltage at the moment of the disturbance. z k is the proportional coefficient for constant impedance loads. i k is the proportional coefficient for constant current loads. p This is the proportional coefficient for constant power load.

[0029] Furthermore, the H min The minimum inertia of the system, considering the occurrence of AC line disconnection or synchronous motor tripping accidents, is expressed as follows:

[0030] (10);

[0031] In the formula, ΔH G This refers to the change in inertia caused by the disconnection of a synchronous generator or a short circuit in the AC line.

[0032] Furthermore, step C involves using the maximum frequency offset as a constraint to evaluate the system's minimum inertia requirement, expressed as follows:

[0033] (11);

[0034] In the formula, t 1 The time it takes for the frequency to reach its maximum offset. K L R is the load frequency regulation effect coefficient. W R is the primary frequency regulation rate of the wind turbine rotor kinetic energy. S Δf3 represents the primary frequency regulation rate of the thermal power unit, and Δf3 represents the maximum frequency offset.

[0035] A computer device includes a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, wherein the processor executes the computer program to implement the steps of a wind turbine frequency regulation control method based on inertia requirements.

[0036] A computer storage medium storing a computer program, wherein when the computer program is executed by a processor, the steps of a wind turbine frequency regulation control method based on inertia requirements are implemented.

[0037] Compared with existing technologies, its advantages are as follows:

[0038] 1. To address the shortcomings of current integrated inertia simulation synchronous machine control and the incomplete consideration of factors in the minimum inertia assessment of the system, this paper proposes a wind turbine rotor kinetic energy optimal frequency output power control scheme based on the minimum inertia requirement of the system, so as to give full play to the flexibility and adaptability of the wind turbine converter control output power.

[0039] 2. Starting from the entire system, and comprehensively considering the frequency response characteristics of the load and synchronous generator, a calculation model for the minimum inertia requirement of the system is established. Based on the evaluation results of the minimum inertia requirement of the system, and combined with the optimization model of the wind turbine frequency regulation process, an improved genetic algorithm is used to solve for the optimal output power of the wind turbine to assist the system frequency regulation, including frequency regulation output power and speed recovery control.

[0040] 3. To provide the system with a certain amount of inertia support quickly, reduce the rate of change and frequency offset under system power imbalance, allow sufficient adjustment time for the first frequency regulation of the system, avoid triggering the third line of defense for the safe and stable operation of my country's power system, and enhance the frequency stability of the power system.

[0041] 4. Considering the advantages of fast frequency response and strong flexibility of the wind turbine rotor kinetic energy control system, an optimal rotor kinetic energy control is proposed, which takes into account the minimum system frequency and the system frequency change rate constraint. By quickly providing inertia support, it actively responds to system frequency fluctuations and improves the system's frequency response capability. Attached Figure Description

[0042] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0043] Figure 1 This is a schematic diagram of the DFIG system structure;

[0044] Figure 2 This is a schematic diagram of the rotor kinetic energy control principle.

[0045] Figure 3 This is a graph showing the rotor kinetic energy control operation curve.

[0046] Figure 4 System inertia output diagram;

[0047] Figure 5 This refers to the system's frequency response process.

[0048] Figure 6 This is a diagram illustrating the process of wind turbines exiting frequency regulation.

[0049] Figure 7 This is a structural diagram of the inertia control principle of a wind farm. Detailed Implementation

[0050] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0051] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0052] Example 1

[0053] Wiring diagram for grid-connected operation of doubly-fed wind turbine generator sets Figure 1 As shown, it includes wind turbines, gearboxes, doubly-fed induction generators (DFIGs), turbine-side converters, and grid-side converters. The turbine-side converter is directly connected to the DFIG and mainly controls the maximum power output of the wind turbine. The grid-side converter is connected to the power grid on one side and to the stator side of the DFIG on the other side, and mainly maintains a constant DC voltage.

[0054] Example 2

[0055] like Figure 2 As shown, frequency regulation considers the inertia characteristics of synchronous generators, the primary frequency regulation characteristics of synchronous generators, the load frequency response characteristics, and the additional frequency response characteristics of wind turbines in the power system. Wherein, ΔP W ΔP represents the change in the output power of the wind turbine. L ΔP represents the change in power absorbed by the load. G Let ΔP be the change in mechanical power of the synchronous generator, and ΔP be the disturbance power. D K represents the system power imbalance. L Where Ts is the load frequency regulation efficiency coefficient, K is the synchronous generator inertial time constant, and K is the load frequency regulation efficiency coefficient. G T is the static characteristic coefficient of the synchronous generator at the frequency. G For the primary frequency regulation time constant of the synchronous generator, the wind turbine speed protection module ω i The minimum operating speed for exiting frequency regulation needs to be determined based on the wind turbine's operating conditions and the power system's minimum inertia requirements, which will be analyzed in detail later. To prevent wind turbines from excessively participating in frequency regulation and causing shutdowns, when the speed is below the minimum limit ω... i When the speed protection module sets the enable signal R to zero, the wind turbine will exit the frequency regulation mode.

[0056] Example 3

[0057] like Figure 3 As shown, the auxiliary frequency control is mainly used to determine the additional active power generated when the wind turbine starts frequency regulation, and to superimpose it with the power value of the maximum power point tracking (MPPT) during normal operation and input it into the converter control module to adjust the output power of the wind turbine and achieve primary frequency regulation.

[0058] Example 4

[0059] The main indicators for evaluating the frequency response characteristics of a system include the maximum frequency drop rate, the maximum frequency offset, and the steady-state frequency. Inertia control based on rotor kinetic energy provides an energy source for electromagnetic power but does not provide unbalanced power to the system; it only buffers unbalanced power. However, it plays a crucial role in maintaining the balance between active power supply and demand, mitigating frequency fluctuations, and buying time for primary frequency regulation. It is an indispensable part of maintaining frequency stability and resists frequency changes.

[0060] The system inertia described in terms of energy can be expressed as:

[0061] E=E SG +E NE +E IM +E L (12);

[0062] In the formula, E SG E represents the inertia of the synchronous generator. NE For the virtual inertia of new energy, E IM E represents the inertia of the asynchronous motor. L This represents the equivalent inertia of a static load. Synchronous generators and loads can provide inertia support without delay. New energy virtual inertia mainly includes two control methods: rotor kinetic energy control and virtual synchronous machine control. However, rotor kinetic energy control has a certain delay, approximately 100ms. Due to slip, asynchronous motors initially provide very little inertia due to frequency fluctuations, but subsequently, the rotational inertia fully responds to frequency changes. A schematic diagram of the supporting power during the system's inertia response process is shown below. Figure 4 As shown.

[0063] The system's inertial constant is:

[0064] (13);

[0065] In the formula, S represents the system capacity.

[0066] The system frequency dynamic equation can be obtained as follows:

[0067] (6);

[0068] In the formula, Hs is a named value, and the rest are per-unit values.

[0069] As can be seen from the above expressions, the main factors affecting the rate of frequency change and the maximum frequency offset are system inertia, generator primary frequency regulation, load frequency characteristics, and wind turbine inertia.

[0070] Example 5

[0071] If the frequency change rate is at its maximum, then this value will be used as a constraint to assess the system's minimum inertia requirement. Since the system frequency is initially unbiased during the disturbance, the synchronous generator and load cannot respond to the system's frequency regulation effect at this point; their frequency change is only related to the system inertia and the disturbance power, as expressed below:

[0072] (14);

[0073] The minimum inertia of the system under the constraint of the rate of change of frequency is:

[0074] (7);

[0075] The above expression shows that when a disturbance power ΔP occurs in the system, in order to ensure that the system frequency change rate does not exceed the maximum value F... max The inertia of the system output after the disturbance must not be less than H. minThe larger the disturbance power ΔP, the larger the minimum inertia required by the system, and vice versa.

[0076] The influence of induced load should also be considered during power disturbances, requiring a correction to the disturbance power. The static voltage equivalent inertia of the induced load should be removed, as expressed below:

[0077] (8);

[0078] In the formula, ΔP U It can be represented as:

[0079] (9);

[0080] In the formula, U0 is the initial voltage before the disturbance, U is the voltage at the instant of the disturbance, and k z k is the proportional coefficient for constant impedance loads. i k is the proportional coefficient for constant current loads. p This is the proportional coefficient for constant power load.

[0081] The above expression does not consider how the disturbance power ΔP occurs. Generally, power disturbances causing system frequency stability problems are usually large generator trips or power differences in tie lines. Different types of disturbances have different effects on the system's inertia level. For example, a DC blocking fault only generates disturbance power ΔP and does not affect the overall system inertia level. If an AC line break or synchronous machine trip occurs, it not only causes system disturbance power ΔP but also reduces system inertia, further deteriorating the system frequency. Therefore, the minimum system inertia in this case is expressed as follows:

[0082] (10);

[0083] In the formula, ΔH G This refers to the change in inertia caused by the disconnection of a synchronous generator or a short circuit in the AC line.

[0084] Regarding the rate of frequency change, my country's power grid has not made explicit requirements, only specifying the maximum frequency deviation. In the UK power grid, the anti-islanding protection setting for distributed generation equipment is set at 0.125 Hz / s, but a major blackout resulted in nearly 350 MW of distributed generation power sources being disconnected from the grid because the system frequency change rate exceeded this setting. Therefore, as the degree of power electronics integration in the power system gradually deepens, the rate of frequency change cannot be ignored.

[0085] Example 6

[0086] To prevent power outages caused by low-frequency load shedding due to power shortage disturbances, the lowest frequency point of the system after a fault should not be lower than the first action value of the low-frequency load shedding of the third line of defense. The maximum offset of this frequency is used as a constraint to evaluate the minimum inertia requirement of the system.

[0087] After the disturbance occurs, the system frequency begins to deviate from its normal value. Initially, due to the small frequency deviation and the dead zones of the frequency regulation devices, none of them operate, and only the load participates in the system frequency response. Because wind turbines have a faster frequency response speed and the frequency response capability of rotor kinetic energy is not sustained, the primary frequency regulation control of the wind turbines begins to operate, and the overall system imbalance gradually decreases. Subsequently, the primary frequency regulation control of the thermal power units begins to take effect. When the output power of the primary frequency regulation control equals the initial imbalance power, the system frequency will reach its limit value. Therefore, the system frequency response occurs in three processes. For this reason, a piecewise linearization method is used to simulate the system's frequency response process, specifically as follows: Figure 5 As shown.

[0088] Figure 5 In the diagram, t1 corresponds to Δf1, t2 to Δf2, and t3 to Δf3. t1 represents the time corresponding to the dead zone of the system's frequency response; t2 represents the time corresponding to the end of frequency regulation for the wind turbine rotor kinetic energy control; and t3 represents the time corresponding to the end of system frequency regulation. During this period, the primary frequency regulation of the thermal power unit mainly bears the system power deficit. For ease of analysis, the system power required for the wind turbine to resume control is also considered during this period. The system frequency response participates throughout the entire process until the power deficit ΔP = 0. Δf3 is the maximum frequency offset, and this frequency deviation is used to assess the system's minimum inertia requirement.

[0089] From the time of the fault occurrence 0 to the time when the system frequency deviation reaches its extreme value t3, the piecewise linearization method is used to integrate and solve equation (1), as follows:

[0090] (15);

[0091] Where, ΔP L =K L Δf, then equation (16) can be expressed as:

[0092] (16);

[0093] In formula (16), The integration should be performed piecewise, as follows:

[0094] During the 0-t1 phase, all frequency control devices are activated, and the system's active power imbalance ΔP remains constant.

[0095] (17);

[0096] During the t1-t2 phase, the wind turbine rotor kinetic energy-assisted frequency control is started. At this time,

[0097] (18);

[0098] In the formula, R W The primary frequency regulation rate of the wind turbine rotor kinetic energy is as follows:

[0099] (19);

[0100] During the t2-t3 phase, the thermal power unit starts with primary frequency regulation. (20); In the formula, R S The primary frequency regulation rate of the thermal power unit is as follows:

[0101] (twenty one);

[0102] Since the power absorbed by the wind turbine recovery control is considered in the t2-t3 stage, the actual frequency regulation power provided by the generator is, then

[0103] (twenty two).

[0104] Example 7

[0105] From the expressions in combined embodiments 5 and 6, it can be seen that the minimum inertia required by the system is:

[0106] (11);

[0107] According to the low-frequency load shedding setting method and scheme of the power system, the frequency setting value for the first round of load shedding in low-frequency load shedding is 49Hz, therefore, Δf3 is 1Hz. Since the system is simultaneously constrained by the rate of frequency change and the maximum frequency offset, its minimum inertia requirement should be the maximum value under both constraints to ensure sufficient system inertia and improve system frequency stability, as detailed below:

[0108] (1).

[0109] Example 8

[0110] The wind turbine provides inertial support to the system through its releasable rotor kinetic energy. The rotor kinetic energy equation of the wind turbine is as follows:

[0111] (twenty three);

[0112] In the formula, H W Let P be the moment of inertia of the wind turbine, ω be the rotor speed of the wind turbine, and P be the moment of inertia of the wind turbine. We P represents the electromagnetic power of the wind turbine. Wm This refers to the mechanical power of the wind turbine.

[0113] During rotor kinetic energy control, the rotor speed of the wind turbine is constrained by a minimum speed limit as it decreases. Therefore, the maximum inertia provided by the wind turbine is:

[0114] (twenty four);

[0115] In the formula, E N The rated speed ω of the wind turbine N The corresponding rotor kinetic energy, E0 is the kinetic energy corresponding to the rotor speed protection lower limit value ω0; P N This refers to the rated power of the wind turbine. Therefore, at the rated speed ω... N The moment of inertia corresponding to any speed ω between the speed protection lower limit ω0 and the speed is:

[0116] (25);

[0117] In the formula, E ω Let ω be the kinetic energy corresponding to the rotor speed ω.

[0118] To quantify the inertia that a wind turbine can provide to a system, an inertia factor k can be defined for wind turbine units. H :

[0119] (26);

[0120] In this invention, ω = 0.7ω N Then equation (3) can be expressed as:

[0121] (27);

[0122] In the formula, ω* is the per-unit value; when ω* is 1, k H =1, when ω* is 0.7, k H =0, therefore, .

[0123] The rotor kinetic energy control of wind turbines provides inertia, which essentially provides power support for the system. The output power is mainly constrained by the upper and lower limits of the converter's power. During rotor kinetic energy control, the electromagnetic power output by the wind turbine is limited by the converter's capacity. The specific constraint equation is as follows:

[0124] (28);

[0125] Rotor kinetic energy control causes changes in the wind turbine speed, which in turn causes changes in the output mechanical power of the wind turbine, i.e., the power variation in formula (6) is changing. According to the literature, the output mechanical power P of the wind turbine is... Wm The relationship between rotational speed and rotational speed can be described as follows:

[0126] (29);

[0127] Because the operating conditions of each wind turbine in the wind farm are different, the output inertia of the wind turbines are different. The output inertia of the entire wind farm is:

[0128] (30);

[0129] In the formula, P Ni Let k be the rated power of the i-th wind turbine. Hi H is the available inertia factor for the i-th wind turbine. maxi Let be the maximum inertia of the i-th wind turbine.

[0130] (31);

[0131] Increasing the primary frequency regulation rate and reducing the settling time of the frequency regulation device can reduce the system's inertia requirements, which is beneficial for the system's primary frequency regulation. For thermal power units, the frequency regulation rate is usually relatively fixed due to the unit's own physical characteristics and stability constraints, and cannot be increased. As for the settling time, advanced communication technology can be used to adopt fault-driven active control, which can shorten the settling time and improve the system's frequency response capability.

[0132] Example 9

[0133] Wind turbine primary frequency regulation based on converter-controlled output power has control parameters that are not physically constrained. Output power can be designed according to actual system requirements, enabling rapid response to system frequency and output of active power, which is equivalent to increasing the frequency regulation rate and reducing the settling time. By using rotor kinetic energy control, the minimum inertia requirement of the system can be effectively reduced, improving the system's frequency regulation capability. The objective of rotor kinetic energy control is to reduce the minimum inertia requirement of the system; the specific objective function is:

[0134] min (H) min (32);

[0135] Based on the mathematical model established above, and then according to the constructed objective function, the output power of the wind farm is solved, and it actively participates in the primary frequency regulation of the system.

[0136] Example 10

[0137] The output power process of wind turbine units is as follows Figure 6 As shown, when the wind turbine speed reaches the lower limit, it exits the frequency regulation mode and enters the speed recovery phase. To prevent secondary frequency drop accidents, the timing of the wind turbine's exit from frequency regulation and the frequency regulation power need to be considered comprehensively, and it needs to be coordinated with the primary frequency regulation of thermal power units to achieve a smooth exit of the wind turbine from frequency regulation and restore the speed to the state before frequency regulation.

[0138] Figure 6 In the middle, t on t is the start time of frequency regulation of the wind turbine. off t is the time when the wind turbine exits frequency regulation. end The end time of wind turbine speed recovery control, P0 is the initial power value of the wind turbine, P f For frequency modulation power, P off To exit FM power.

[0139] During the speed recovery process, the change in rotor speed is still determined by the rotor motion equation of the wind turbine. By integrating both sides of equation (23), the output power P of the wind turbine rotor speed recovery control can be obtained. e (t).

[0140] This invention proposes an approximate solution using a piecewise linearization approach. Assuming a single piece of linearization is used for description, the expression for the output power is:

[0141] (2);

[0142] In the formula, k p The output power coefficient is as follows:

[0143] (3);

[0144] Where, ω off This refers to the fan speed when frequency regulation is discontinued.

[0145] In the formula, It can be described as t off Approximate linear function, i.e.

[0146] P off =P f +k f (t) off -t on (4);

[0147] in,

[0148] (5);

[0149] The same method can be used to obtain multi-segment linearized output power curves, enabling wind turbine speed recovery control. Speed ​​recovery control primarily depends on the frequency regulation exit time t. off and frequency modulation power P f And the power P of frequency modulation is withdrawn off And P f and P off It is determined by the real-time inertia of the wind turbine.

[0150] Meanwhile, in order to ensure the normal operation of the wind turbine's speed recovery, the speed change rate needs to be set, specifically:

[0151] (33);

[0152] Based on the frequency regulation characteristics of thermal power units and loads, and according to the established auxiliary frequency regulation equations for wind turbine units, the solution is obtained according to the optimization objective function.

[0153] Example 11

[0154] Based on the same inventive concept, embodiments of the present invention also provide a computer device, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor. When the processor executes the computer program, it implements the steps of the wind turbine frequency regulation control method based on inertia requirements described in Embodiment 1.

[0155] Example 12

[0156] Based on the same inventive concept, this embodiment of the invention also provides a computer storage medium storing a computer program, which, when executed by a processor, implements the steps of the wind turbine frequency regulation control method based on inertia requirements described in Embodiment 1.

[0157] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0158] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0159] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0160] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0161] In the description of this specification, the terms "one embodiment," "some embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A frequency regulation control method for wind turbine units based on inertia requirements, characterized in that, The steps include: A. Analyzing the main factors affecting the system's frequency response characteristics; B. Based on the analysis results, the rate of change of frequency is used as a constraint to evaluate the minimum inertia requirement of the system; C. Based on the analysis results, the maximum frequency offset is used as a constraint to evaluate the minimum inertia requirement of the system; D. Use the maximum value of the above two constraints as the minimum inertia requirement of the system to ensure sufficient inertia and improve the frequency stability of the system; using the maximum value of the above two constraints as the minimum inertia requirement of the system means using the maximum value of the frequency change rate and the maximum frequency offset constraints in steps B and C as the minimum inertia requirement of the system, as expressed below: （1）; E. Based on the above results, construct an objective function to obtain the output power of the wind turbine, which will then participate in system frequency regulation; the expression for obtaining the output power of the wind turbine is as follows: （2）； In the formula, k p The output power coefficient is as follows: （3）； Where, ω off This refers to the fan speed when frequency regulation is discontinued; In the formula, P 0 This represents the initial output power of the wind turbine. P m This represents the maximum output power of the wind turbine. ω 0 represents the initial speed of the wind turbine, t off To exit FM time, P f For frequency modulation power, P off To exit FM power, It can be described as t off Approximate linear function, i.e. P off =P f +k f (t off -t on ) (4); in, t on This is the start time of frequency regulation for the wind turbine. （5）； In the formula, K f This is the frequency modulation power withdrawal coefficient. K MPPT The maximum power point tracking coefficient, Hw Let be the inertial constant of the wind turbine.

2. The wind turbine frequency regulation control method based on inertia demand according to claim 1, characterized in that, Step A describes the analysis of the main factors affecting the system's frequency response characteristics, which yields the system's frequency dynamic equation, expressed as follows: （6）； In the formula: Δf is the system frequency deviation, t is time, and Δ P G Δ represents the change in output power of the synchronous generator set. P W Δ represents the change in the output power of the wind turbine. P L This represents the change in load power. S Here, Hs is the system inertia, ΔP is the disturbance power, and Hs is a named value; the rest are per-unit values.

3. The wind turbine frequency regulation control method based on inertia demand according to claim 1, characterized in that, Step B involves using the rate of change of frequency as a constraint to assess the minimum inertia requirement of the system, and its expression is as follows: （7）； In the formula, t0 is the initial time of the disturbance; H min Let F be the minimum inertia of the system, ΔP be the disturbance power, and F be the inertia of the system. max This represents the maximum rate of change of the system frequency.

4. The wind turbine frequency regulation control method based on inertia demand according to claim 3, characterized in that, The H min To determine the minimum inertia of the system, when considering the influence of induced loads, the disturbance power needs to be corrected to remove the static voltage equivalent inertia of the induced load. The expression is as follows: （8）； In the formula, ΔP U It can be represented as: （9）； In the formula, Δ Pu This is the correction amount for the disturbance power in response to the static voltage response of the induced load. P L0 Let U be the total active load of the system before the disturbance, U0 be the initial voltage before the disturbance, U be the voltage at the moment of the disturbance, and k be the voltage at the moment of the disturbance. z k is the proportional coefficient for constant impedance loads. i k is the proportional coefficient for constant current loads. p This is the proportional coefficient for constant power load.

5. The wind turbine frequency regulation control method based on inertia requirement according to claim 3, characterized in that, The H min The minimum inertia of the system, considering the occurrence of AC line disconnection or synchronous motor tripping accidents, is expressed as follows: （10）； In the formula, ΔH G This refers to the change in inertia caused by the disconnection of a synchronous generator or a short circuit in the AC line.

6. The wind turbine frequency regulation control method based on inertia demand according to claim 1, characterized in that, Step C describes using the maximum frequency offset as a constraint to evaluate the system's minimum inertia requirement, expressed as follows: （11）； In the formula, t 1 The time it takes for the frequency to reach its maximum offset. K L R is the load frequency regulation effect coefficient. W R is the primary frequency regulation rate of the wind turbine rotor kinetic energy. S Δf3 represents the primary frequency regulation rate of the thermal power unit, and Δf3 represents the maximum frequency offset.

7. A computer device, comprising a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the frequency regulation control method for wind turbine generators based on inertia requirements as described in any one of claims 1-6.

8. A computer storage medium, characterized in that, The computer storage medium contains a computer program, which, when executed by a processor, implements the steps of the wind turbine frequency regulation control method based on inertia requirements as described in any one of claims 1-6.

Images