Method and system for adjusting frequency of power grid through combination of wind and storage

Abstract

The invention relates to the technical field of power system frequency stability analysis, and discloses a method and system for adjusting the frequency of a power grid through wind and storage combination, and the method comprises the steps that a fan carries out the frequency adjustment of the system through comprehensive inertia control, so as to compensate for the lacked power; variable-coefficient rotating speed recovery control is adopted for the fan, so that active power output by the fan is slowly reduced, and the rotating speed of a fan rotor is recovered; the energy storage device is connected with the fan in parallel, if the residual capacity of the energy storage device is higher than the set threshold value, the energy storage device outputs the energy storage power for supplementing the load shedding power of the fan, the technical problem that the system frequency secondary drop is caused by sudden power change is solved, and the technical effect of suppressing the frequency secondary drop is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of power system frequency stability analysis, and in particular to a method and system for wind power generation and storage combined with power grid frequency regulation. Background Art

[0002] The development and utilization of new energy sources have become the focus of people's attention. Wind power has become the most competitive new energy power generation technology due to its advantages such as low cost and mature technology. Large-scale wind power grid connection also brings new challenges to the stability of system frequency. On the one hand, wind turbines are connected to the grid through converters, so that the direct coupling relationship between the wind turbine rotor speed and the system frequency is lost; on the other hand, in order to achieve effective utilization of wind energy, wind turbines usually use maximum power point tracking (MPPT) control, which cannot regulate the system frequency. When the system frequency decreases, the wind turbine releases the rotor kinetic energy for short-term power support. As the rotor kinetic energy is gradually released, when the generator speed drops to the lower limit of the speed, the wind turbine exits the primary frequency modulation and uses MPPT control to recover the speed. In the early stage of the speed recovery stage, the sharp drop in electromagnetic torque causes the active power output of the wind turbine to drop suddenly (power mutation), which will cause a secondary drop in the system frequency. Summary of the invention

[0003] The present application provides a method and system for wind and energy storage combined with power grid frequency regulation, which solves the technical problem of secondary frequency drop of the system caused by power mutation, and achieves the technical effect of suppressing secondary frequency drop.

[0004] In order to achieve the above objectives, the main technical solutions adopted in this application include:

[0005] In a first aspect, an embodiment of the present application provides a method for jointly regulating the frequency of a power grid by wind and energy storage, the method comprising: the wind turbine adopts integrated inertia control to adjust the frequency of the system to compensate for the lack of power; the wind turbine adopts variable coefficient speed recovery control so that the active power output by the wind turbine slowly decreases and the wind turbine rotor recovers the speed; an energy storage device is connected in parallel with the wind turbine, and if the remaining capacity of the energy storage device is higher than a set threshold, the energy storage device outputs the energy storage power to supplement the load shedding power of the wind turbine.

[0006] The method for jointly regulating the grid frequency by wind and energy storage proposed in the embodiment of the present application uses integrated inertia control on the wind turbine to adjust the frequency of the system to compensate for the lack of power. The wind turbine uses variable coefficient speed recovery control to slowly reduce the active power output by the wind turbine, and restore the speed of the wind turbine rotor, thereby suppressing the sudden drop in the active power output by the wind turbine and avoiding a secondary drop in the system frequency. An energy storage device is connected in parallel with the wind turbine. If the remaining capacity of the energy storage device is higher than the set threshold, the energy storage device outputs the stored energy power to supplement the load shedding power of the wind turbine, thereby solving the technical problem of the secondary drop in the system frequency caused by the decrease in the active power output by the wind turbine from the root.

[0007] Optionally, the fan adopts integrated inertia control to adjust the frequency of the system to compensate for the lack of power, wherein the additional power generated by the fan is ΔP, which can be expressed as:

[0008]

[0009] In the above formula, K p , K d They are the proportional coefficient and differential coefficient of comprehensive inertia control respectively, Δf is the system frequency deviation, and df / dt is the system frequency change rate.

[0010] Optionally, the fan adopts variable coefficient speed recovery control, so that the active power output by the fan is slowly reduced, and the fan rotor recovers the speed, wherein the active power output by the fan is P W (t), can be expressed as:

[0011] P w (t) = P MPPT (t)+ΔP(t)-ΔP de (t)

[0012] In the above formula, P MPPT (t) is the maximum power of the wind turbine in the maximum power tracking mode at time t, ΔP(t) is the additional power generated by the wind turbine at time t, and ΔP de (t) is the load reduction power of the fan at time t.

[0013] Optionally, the maximum power of the wind turbine operating in the maximum power tracking mode is P MPPT , which can be expressed as:

[0014] P MPPT =0.5ρπr 5 C p_max ω 3 / λ 3 opt =k max ω 3

[0015] In the above formula, ρ is the air density, r is the radius of the fan blade, C p_max is the maximum utilization coefficient of wind energy, λ opt is the fan tip speed ratio, ω is the fan speed, k max is the maximum power factor.

[0016] Optionally, the load reduction power of the fan at time t is ΔP de (t), can be expressed as:

[0017] ΔP de (t) = k P (ω0-ω r )+k I ∫(ω0-ω r )dt

[0018] In the above formula, k P is the proportional coefficient of comprehensive inertia control, k I is the integral coefficient of comprehensive inertia control, ω0 is the fan rotor speed before disturbance, ω r is the fan rotor speed at time t.

[0019] Optionally, according to the variable coefficient speed recovery control, the proportional coefficient of the comprehensive inertia control and the integral coefficient of the comprehensive inertia control are determined, which can be expressed as:

[0020]

[0021] In the above formula, k P is the proportional coefficient of comprehensive inertia control, k I is the integral coefficient of comprehensive inertia control, t off is the moment of entering speed recovery, ω(t off ) is t off The fan rotor speed at the moment, ω r is the fan rotor speed at time t, a P and a I k P and k I The proportionality factor.

[0022] Optionally, the energy storage device outputs energy storage power P E , which can be expressed as:

[0023] P E =k P (ω0-ω r )+k I ∫(ω0-ω r )dt

[0024] In the above formula, k P is the proportional coefficient of comprehensive inertia control, kI is the integral coefficient of comprehensive inertia control, ω0 is the fan rotor speed before disturbance, ω r is the fan rotor speed at time t.

[0025] The energy storage power output by the energy storage device is equal to the load reduction power of the fan. The energy storage device dynamically adjusts the energy storage power output by the energy storage device according to the changing characteristics of the fan rotor speed to compensate for the load reduction power of the fan, fundamentally solving the technical problem of secondary frequency drop caused by sudden change in the fan output active power.

[0026] Optionally, the method further includes: when the system is disturbed, if the frequency deviation of the system exceeds a first threshold and the fan rotor speed exceeds a second threshold, the fan uses integrated inertia control to adjust the frequency of the system to compensate for the missing power.

[0027] Optionally, the first threshold is 0.03 Hz, and the second threshold is 0.67 pu.

[0028] Optionally, the method further includes: if the fan rotor speed begins to recover, or the fan rotor speed is lower than the second threshold, the fan adopts variable coefficient speed recovery control so that the active power output by the fan slowly decreases.

[0029] In a second aspect, an embodiment of the present application provides a system for jointly regulating the frequency of a power grid by wind and energy storage, including: a control module, for the wind turbine to use integrated inertia control to adjust the frequency of the system to compensate for the lack of power; a variable coefficient speed recovery control for the wind turbine to slowly reduce the active power output by the wind turbine and restore the speed of the wind turbine rotor; an energy storage module, for connecting an energy storage device in parallel with the wind turbine, and if the remaining capacity of the energy storage device is higher than a set threshold, the energy storage device outputs the energy storage power to supplement the load shedding power of the wind turbine.

[0030] In a third aspect, a computer device proposed in an embodiment of the present application includes: a memory and a processor, the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes any one of the above-mentioned methods for jointly regulating grid frequency by wind and energy storage by executing the computer instructions.

[0031] In a fourth aspect, an embodiment of the present application proposes a computer-readable storage medium, on which computer instructions are stored, and the computer instructions are used to enable a computer to execute any of the above-mentioned methods for jointly regulating grid frequency by wind and energy storage.

[0032] In a fifth aspect, a computer program product proposed in an embodiment of the present application includes computer instructions, and the computer instructions are used to enable a computer to execute any of the above-mentioned methods for jointly regulating grid frequency by wind and energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 A schematic diagram of wind turbine output in an application scenario where wind power storage jointly regulates grid frequency;

[0035] Figure 2 A flow chart of a method for wind power storage combined with power grid frequency regulation provided in an embodiment of the present application;

[0036] Figure 3 A specific implementation flow chart of the method for wind power storage combined with power grid frequency regulation provided in the embodiment of the present application;

[0037] Figure 4 A schematic diagram of a system for wind and energy storage combined with power grid frequency regulation is provided for the embodiment of the present application;

[0038] Figure 5 A schematic diagram of the structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0040] In order to improve the frequency stability of the power system under large-scale wind power grid connection, the wind turbine should have the ability to adjust the frequency, which can be achieved through power reserve control and rotor kinetic energy control. Power reserve control needs to be achieved with the help of wind turbine overspeed control or pitch angle control. The wind turbine is operated in load reduction mode to reserve spare capacity for frequency adjustment. However, long-term load reduction mode will reduce the utilization efficiency of wind energy and the economic benefits of the wind farm, or increase the mechanical wear of the wind turbine, which has certain limitations. Rotor kinetic energy control is also called integrated inertia control, which mainly includes virtual inertia control and droop control. Integrated inertia control adjusts the speed of the wind turbine rotor, uses rotor kinetic energy to provide active support, and simulates the inertial response of the synchronous generator, thereby actively participating in frequency regulation. The integrated inertia control method will not affect the effective utilization of wind energy by wind turbines during normal operation, so it has good application prospects. The integrated inertia control unit integrates virtual inertia and droop control technologies. Wind turbines go through two key stages during frequency regulation: frequency support and speed recovery. The virtual inertia control mechanism can intervene quickly when the system frequency drops sharply, providing support for the instantaneous frequency and helping to reduce the frequency fluctuation amplitude, but the effect on long-term steady-state frequency regulation is limited. On the other hand, the droop control implemented by wind turbines actively reduces the load power and cooperates with the primary frequency regulation mechanism of the synchronous generator to enhance the steady-state frequency regulation performance of the system.

[0041] The schematic diagram of wind turbine output using wind energy storage combined with integrated inertia control to adjust grid frequency is shown in the attached figure. Figure 1 shown. Figure 1 In the above equation, ω(t0), ω(t B ),ω(t C ) and ω(t E ) are t0, t B ,t C ,t E The fan rotor speed at points A, B, C and E corresponding to the time; P0, P B , P C and P D are t0 and t B ,t C ,t D The wind turbine capture power at points A, B, C and D corresponding to the time; ΔP deis the load reduction power for DFIG fan speed recovery. Among them, point A indicates that the system is in a steady state. At this time, the fan operates at the maximum power output point. When the load changes and the system is disturbed, the fan releases the rotor kinetic energy to respond to the frequency change, from A to B to C, which represents the frequency support stage. The fan uses comprehensive inertia control to adjust the frequency of the system to compensate for the lack of power. After the fan releases its own kinetic energy to provide frequency support for the system, if the rotor kinetic energy is not replenished in time, it will not only lead to a decrease in wind energy utilization, but may even cause the fan to stall, aggravating the imbalance of the system, and causing serious secondary frequency drops. From C to D to E to A, it represents the speed recovery stage. Related technologies usually use the following Figure 1 The constant power speed recovery strategy shown in Figure 1 The fan is suddenly unloaded from point C to point D, and the fan runs at a constant output power from point D to point E of the MPPT curve, and then the fan rotor speed along the MPPT curve is restored to the initial value of point A. However, the sudden load reduction at point C will aggravate the unbalanced power of the system and may cause a secondary drop in frequency. If it is not controlled, it may even be more serious than the primary drop in frequency.

[0042] like Figure 1 As shown, at the initial stage of speed recovery, i.e., t off At this moment, the fan exits frequency regulation and Figure 1 From point C to point D in the figure, the fan reduces the electromagnetic power to meet the necessary and sufficient conditions for the recovery of the fan rotor speed (the electromagnetic torque is less than the mechanical torque), t off Unbalanced power ΔP in the system at the moment E (t off )for:

[0043] ΔP E (t off )=(P L0 +ΔP L )-P G (t off )-[P W (t off )-ΔP de ] (1)

[0044] In the above formula, P L0 is the initial load value, ΔP L is the load disturbance value, P G (t off ) is t off Active power of the time-synchronous machine, P w (t off ) is t off Active power output of the fan at the moment, ΔP de is the load reduction power of the fan.

[0045] The power generation part of the system includes synchronous machines and wind turbines. When the wind turbine exits the frequency modulation, only the synchronous machine participates in the frequency modulation. During the recovery of the wind turbine rotor speed, the rotor motion equation of the synchronous machine can be expressed as:

[0046]

[0047] In the above formula, T G Represents the time constant of the synchronous machine speed regulator action, K G Represents the unit regulation power of the synchronous machine, ΔP G Represents the additional power of the synchronous machine, ΔP E (t off ) represents t off is the unbalanced power in the system at moment 1, H is the inertia time constant of the conventional synchronous unit, f is the system frequency, and Δf is the system frequency deviation.

[0048] Substituting equation (3) into equation (2), the frequency change equation in the speed recovery stage is:

[0049] 2HT G f″+2Hf′+K G f=K G f off -ΔP E (t off )

[0050] Where f' and f" are the first and second derivatives of the system frequency, respectively. off t off The system frequency at time T G Represents the time constant of the synchronous machine speed regulator action, K G Represents the unit regulation power of the synchronous machine, ΔP E (t off ) represents t off is the unbalanced power in the system at moment 1, H is the inertia time constant of the conventional synchronous unit, and f is the system frequency.

[0051] The initial conditions are as follows:

[0052]

[0053] Substituting equation (5) into equation (4), the time domain expression of the system frequency in the speed recovery stage is:

[0054]

[0055] In the above formula, α, ω2 and θ2 are intermediate variables, and their expressions are:

[0056]

[0057] Further deriving equation (7), we can obtain the maximum deviation Δf of the secondary frequency drop: * max for

[0058]

[0059] In the formula, γ = arctan(ω2 / α).

[0060] From formula (8), we can know that the maximum deviation of the second frequency drop Δf * max and the unbalanced power ΔP in the system E (t off ) and t off The system frequency f off There is a close relationship. In the early stage of speed recovery, the fan exits frequency regulation and the unbalanced power ΔP in the system E (t off ) is mainly composed of the fan load reduction power ΔP de Produced; From formula (1), it can be seen that the unbalanced power ΔP in the system E (t off ) and the fan load reduction power ΔP de Positive correlation. The maximum deviation Δf that affects the secondary drop of frequency * max The main factor is the fan load reduction power ΔP de .

[0061] According to an embodiment of the present application, a method embodiment of wind power storage combined with grid frequency regulation is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0062] Figure 2 This is a flow chart of a method for wind power storage combined with power grid frequency regulation according to an embodiment of the present application, the process includes the following steps:

[0063] Step S1, the fan uses comprehensive inertia control to adjust the system frequency to compensate for the lack of power.

[0064] Among them, the additional power of the wind turbine is determined according to the system frequency deviation and the system frequency change rate to compensate for the missing power and enter the frequency support stage.

[0065] In step S3, the fan adopts variable coefficient speed recovery control so that the active power output by the fan slowly decreases and the fan rotor recovers its speed; the energy storage device is connected in parallel with the fan. If the remaining capacity of the energy storage device is higher than the set threshold, the energy storage device outputs the energy storage power to supplement the load shedding power of the fan.

[0066] The method for jointly regulating the grid frequency by wind and energy storage proposed in the embodiment of the present application uses integrated inertia control on the wind turbine to adjust the frequency of the system to compensate for the lack of power. The wind turbine uses variable coefficient speed recovery control to slowly reduce the active power output by the wind turbine, and restore the speed of the wind turbine rotor, thereby suppressing the sudden drop in the active power output by the wind turbine and avoiding a secondary drop in the system frequency. An energy storage device is connected in parallel with the wind turbine. If the remaining capacity of the energy storage device is higher than the set threshold, the energy storage device outputs the stored energy power to supplement the load shedding power of the wind turbine, thereby solving the technical problem of the secondary drop in the system frequency caused by the decrease in the active power output by the wind turbine from the root.

[0067] like Figure 3 As shown, it is a specific implementation flow chart of the method for wind-storage combined regulation of grid frequency provided by the embodiment of the present application, including: when the system is disturbed, if the frequency deviation of the system exceeds the first threshold value, and the wind turbine rotor speed exceeds the second threshold value, then the frequency support stage is entered, and the wind turbine uses comprehensive inertia control to regulate the frequency of the system to compensate for the lack of power. For example, the first threshold value is set to 0.03 Hz, and the second threshold value is set to 0.67 pu.

[0068] For example, when the load changes and the system is disturbed, causing the system frequency to decrease, if the system frequency fluctuation exceeds the dead zone, that is, if the system frequency deviation exceeds 0.03HZ, and the fan rotor speed exceeds the minimum speed of 0.67pu, it enters the frequency support stage, and the fan releases the rotor kinetic energy to respond to the system frequency change, and uses comprehensive inertia control to adjust the system frequency. In the frequency support stage, the energy storage power output by the energy storage device is zero.

[0069] The additional power of the fan is determined based on the system frequency deviation and the system frequency change rate to compensate for the lack of power. The additional power required by the fan is ΔP, which can be expressed as:

[0070]

[0071] In the above formula, K p , K d They are the proportional coefficient and differential coefficient of comprehensive inertia control respectively, Δf is the system frequency deviation, and df / dt is the system frequency change rate.

[0072] like Figure 3 As shown, the fan rotor speed is obtained. If the fan rotor speed begins to recover, that is, dω r / dt>0,(ωr is the fan rotor speed at time t), or the fan rotor speed is lower than the minimum speed of 0.67pu, it enters the speed recovery stage, and the fan adopts variable coefficient speed recovery control to slowly reduce the active power output of the fan, and the fan begins to reduce load to restore the fan rotor kinetic energy, that is, Figure 1 There is no power mutation between point C and point E (power mutation refers to point C to point D), but it slowly decreases from point C to point E. In addition, the energy storage device is connected in parallel with the wind turbine. When entering the speed recovery stage, if the remaining capacity of the energy storage device, that is, the energy storage charge, is higher than the set threshold, that is, the minimum limit, the energy storage device outputs the energy storage power, performs energy storage auxiliary frequency regulation, compensates for the load reduction power of the wind turbine, and reduces the amplitude of the secondary drop of the system frequency.

[0073] In the speed recovery stage, the active power output of the fan is P W (t), can be expressed as:

[0074] P w (t) = P MPPT (t)+ΔP(t)-ΔP de (t) (10)

[0075] In the above formula, P MPPT (t) is the maximum power of the wind turbine operating in the MPPT maximum power tracking mode at time t, ΔP(t) is the additional power generated by the wind turbine at time t, ΔP de (t) is the load reduction power of the fan at time t.

[0076] The maximum power of the wind turbine in the MPPT maximum power tracking mode is P MPPT , which can be expressed as:

[0077] P MPPT =0.5ρπr 5 C p_max ω 3 / λ 3 opt =k max ω 3 (13)

[0078] In the above formula, ρ is the air density, r is the radius of the fan blade, C p_max is the maximum utilization coefficient of wind energy, λ opt is the fan tip speed ratio, ω is the fan speed, k max is the maximum power factor.

[0079] In the speed recovery stage, the system rotor motion equation and the fan rotor motion equation are:

[0080]

[0081] In the formula, H DFIG is the virtual inertia provided by the fan. From equations (11) and (12), it can be seen that by changing ΔP de (t) can adjust the fan rotor speed recovery and system frequency secondary drop performance. In formula (12), since the fan is in the speed recovery stage, the system frequency approaches the quasi-steady state, resulting in a small change in the additional power ΔP(t) of the fan, and the load reduction power ΔP output by the fan de (t) plays a leading role in the speed recovery process, and a larger ΔP is used de (t) can achieve rapid recovery of the fan rotor speed, but the sudden change in the fan output active power in the early stage of speed recovery will cause unbalanced power ΔP in the system. E Increase, resulting in serious secondary frequency drop, it is difficult to take into account both the suppression of secondary frequency drop and the speed recovery performance.

[0082] In order to solve the technical problem that the active power output of the fan suddenly changes in the early stage of speed recovery, causing the system frequency to drop twice, the embodiment of the present application adopts variable coefficient speed recovery control, so that the active power output of the fan in the speed recovery stage is slowly reduced to avoid the secondary drop of the system frequency. Among them, the load reduction power of the fan at time t is ΔP de (t), can be expressed as:

[0083] ΔP de (t) = k P (ω0-ω r )+k I ∫(ω0-ω r )dt (14)

[0084] In the above formula, k P is the proportional coefficient of comprehensive inertia control, k I is the integral coefficient of comprehensive inertia control, ω0 is the fan rotor speed before disturbance, ω r is the fan rotor speed at time t.

[0085] According to the variable coefficient speed recovery control, the proportional coefficient of the integrated inertia control and the integral coefficient of the integrated inertia control are determined, which can be expressed as:

[0086]

[0087] In the above formula, k P is the proportional coefficient of comprehensive inertia control, k I is the integral coefficient of comprehensive inertia control, t off is the moment of entering the speed recovery phase, ω(t off ) is t off The fan rotor speed at the moment, ω ris the fan rotor speed at time t, a P and a I k P and k I The proportionality factor.

[0088] At the beginning of the speed recovery phase, k P , k I With the speed difference [ω r -ω(t off )] starts to increase from 0, avoiding power mutation and suppressing the secondary frequency drop problem caused by power mutation; k P and k I It increases with the increase of fan rotor speed, and the deviation between fan input power and output power increases, which accelerates the recovery speed of fan rotor speed.

[0089] In some embodiments, the energy storage power output by the energy storage device is equal to the load reduction power of the wind turbine. The energy storage device dynamically adjusts the energy storage power output by the energy storage device according to the changing characteristics of the wind turbine rotor speed to compensate for the load reduction power of the wind turbine, thereby fundamentally solving the problem of secondary frequency drop caused by sudden changes in the wind turbine output active power.

[0090] The energy storage power P output by the energy storage device E It can be expressed as:

[0091] P E =k P (ω0-ω r )+k I ∫(ω0-ω r )dt (16)

[0092] In the above formula, k P is the proportional coefficient of comprehensive inertia control, k I is the integral coefficient of comprehensive inertia control, ω0 is the fan rotor speed before disturbance, ω r is the fan rotor speed at time t.

[0093] When the wind turbine rotor speed gradually recovers to the MPPT maximum power point tracking curve, the energy storage power output by the energy storage device decreases smoothly as the wind turbine rotor speed increases.

[0094] Accordingly, please refer to Figure 4The embodiment of the present application provides a system for jointly regulating the frequency of a power grid by wind and energy storage, including: a control module, which is used for the wind turbine to use comprehensive inertia control to adjust the frequency of the system to compensate for the lack of power; a variable coefficient speed recovery control is used for the wind turbine to slowly reduce the active power output by the wind turbine and restore the speed of the wind turbine rotor; an energy storage module, which is used to connect the energy storage device in parallel with the wind turbine. If the remaining capacity of the energy storage device is higher than a set threshold, the energy storage device outputs the energy storage power to supplement the load shedding power of the wind turbine.

[0095] The further functional description of each of the above modules is the same as that of the above corresponding embodiments and will not be repeated here.

[0096] The system for jointly regulating grid frequency by wind and storage in this embodiment is presented in the form of functional units, where the units refer to ASIC (Application Specific Integrated Circuit) circuits, processors and memories that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0097] See also Figure 5 , Figure 5 is a schematic diagram of the structure of a computer device provided in an embodiment of the present application, such as Figure 5As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. The various components are connected to each other using different buses for communication, and can be installed on a common motherboard or installed in other ways as needed. The processor can process instructions executed in the computer device, including instructions stored in or on the memory to display graphical information of the GUI on an external input / output device (such as a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). The processor 10 can be a central processing unit, a network processor or a combination thereof. Among them, the processor 10 can further include a hardware chip. The above-mentioned hardware chip can be a dedicated integrated circuit, a programmable logic device or a combination thereof. The above-mentioned programmable logic device can be a complex programmable logic device, a field programmable logic gate array, a general array logic or any combination thereof. The memory 20 stores instructions executable by at least one processor 10 so that the at least one processor 10 executes the method shown in the above embodiment. The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required by at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage devices. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof. The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid-state hard disk; the memory 20 may also include a combination of the above-mentioned types of memory. The computer device also includes a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0098] The embodiment of the present application also provides a computer-readable storage medium. The above method according to the embodiment of the present application can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0099] The embodiment of the present application provides a computer program product, which includes computer instructions, which are stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the method of any embodiment of the present application.

[0100] Although the embodiments of the present application are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations are all within the scope defined by the appended claims.

[0101] The systems or modules described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0102] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0103] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0104] The present application is described with reference to the flowcharts and / or block diagrams of the methods, systems, and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0105] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0106] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0107] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0108] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0109] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

[0110] Although the embodiments of the present application have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for jointly regulating grid frequency with wind and energy storage. It is characterized in that The method comprises: The fan uses integrated inertia control to adjust the system frequency to compensate for the lack of power; The fan adopts variable coefficient speed recovery control, so that the active power output of the fan is slowly reduced and the fan rotor recovers its speed; The energy storage device is connected in parallel with the wind turbine. If the remaining capacity of the energy storage device is higher than the set threshold, the energy storage device outputs the stored energy power to supplement the load shedding power of the wind turbine.

2. The method according to claim 1, It is characterized in that The fan adopts comprehensive inertia control to adjust the frequency of the system to compensate for the lack of power, wherein the additional power generated by the fan is ΔP, which can be expressed as: In the above formula, K p , K d They are the proportional coefficient and differential coefficient of comprehensive inertia control respectively, Δf is the system frequency deviation, and df / dt is the system frequency change rate.

3. The method according to claim 1, It is characterized in that The fan adopts variable coefficient speed recovery control, so that the active power output of the fan is slowly reduced, and the fan rotor recovers the speed, wherein the active power output of the fan is P W (t), can be expressed as: P w (t)=P MPPT (t)+ΔP(t)-ΔP de (t) In the above formula, P MPPT (t) is the maximum power of the wind turbine in the maximum power tracking mode at time t, ΔP(t) is the additional power generated by the wind turbine at time t, and ΔP de (t) is the load reduction power of the fan at time t.

4. The method according to claim 3, It is characterized in that The maximum power of the fan in the maximum power tracking mode is P MPPT , which can be expressed as: P MPPT =0.5ρπr 5 C p_max oh 3 / l 3 opt =k max oh 3 In the above formula, ρ is the air density, r is the radius of the fan blade, C p_max is the maximum utilization coefficient of wind energy, λ opt is the fan tip speed ratio, ω is the fan speed, k max is the maximum power factor.

5. The method according to claim 3, It is characterized in that The load reduction power of the fan at time t is ΔP de (t), can be expressed as: ΔP de (t)=k P (oh 0 -oh r )+k I ∫(ω 0 -oh r )dt In the above formula, k P is the proportional coefficient of comprehensive inertia control, k I is the integral coefficient of comprehensive inertia control, ω 0 is the fan rotor speed before disturbance, ω r is the fan rotor speed at time t.

6. The method according to claim 5, It is characterized in that According to the variable coefficient speed recovery control, the proportional coefficient of the comprehensive inertia control and the integral coefficient of the comprehensive inertia control are determined, which can be expressed as: In the above formula, k P is the proportional coefficient of comprehensive inertia control, k I is the integral coefficient of comprehensive inertia control, t off is the moment of entering speed recovery, ω(t off ) is t off The fan rotor speed at the moment, ω r is the fan rotor speed at time t, a P and a I k P and k I The proportionality factor.

7. The method according to claim 1, It is characterized in that The energy storage device outputs energy storage power P E , which can be expressed as: P E =k P (ω 0 -ω r )+k I ∫(ω 0 -ω r )dt In the above formula, k P is the proportional coefficient of comprehensive inertia control, k I is the integral coefficient of comprehensive inertia control, ω 0 is the fan rotor speed before disturbance, ω r is the fan rotor speed at time t.

8. The method according to claim 1, It is characterized in that The method further comprises: When the system is disturbed, if the frequency deviation of the system exceeds a first threshold and the fan rotor speed exceeds a second threshold, the fan uses integrated inertia control to adjust the frequency of the system to compensate for the missing power.

9. The method according to claim 8, It is characterized in that The first threshold is 0.03 Hz, and the second threshold is 0.67 pu.

10. The method according to claim 8, It is characterized in that The method further comprises: If the fan rotor speed begins to recover, or the fan rotor speed is lower than the second threshold, the fan adopts variable coefficient speed recovery control so that the active power output by the fan slowly decreases.

11. A system for wind and energy storage to jointly regulate the frequency of the power grid. It is characterized in that include: Control module, used for fans to adjust the system frequency using integrated inertia control to compensate for the lack of power; Used for variable coefficient speed recovery control of the fan, so that the active power output of the fan is slowly reduced and the fan rotor recovers its speed; The energy storage module is used to connect the energy storage device in parallel with the wind turbine. If the remaining capacity of the energy storage device is higher than the set threshold, the energy storage device outputs the energy storage power to supplement the load shedding power of the wind turbine.

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