CN111900742B - Frequency modulation method of wind storage system based on double-layer cooperative control - Google Patents

Frequency modulation method of wind storage system based on double-layer cooperative control Download PDF

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CN111900742B
CN111900742B CN202010633145.0A CN202010633145A CN111900742B CN 111900742 B CN111900742 B CN 111900742B CN 202010633145 A CN202010633145 A CN 202010633145A CN 111900742 B CN111900742 B CN 111900742B
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frequency
wind
power
inertia
cooperative control
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CN111900742A (en
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彭晓涛
梁恺
秦世耀
王靖然
张政
李华取
陈人杰
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Wuhan University WHU
State Grid Jibei Electric Power Co Ltd
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State Grid Jibei Electric Power Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/30—Arrangements for balancing of the load in a network by storage of energy using dynamo-electric machines coupled to flywheels
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/466—Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/16—Mechanical energy storage, e.g. flywheels or pressurised fluids
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

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Abstract

The invention relates to a frequency modulation method of a wind storage system based on double-layer cooperative control, and provides a two-layer cooperative control scheme for a flywheel energy storage cooperative MPPT operation wind turbine generator set to provide frequency modulation response based on a cooperative control theory from the aspect of optimizing the frequency response dynamic characteristic of the wind storage system. The frequency deviation and the virtual electrical inertia of the wind turbine generator are linearly combined to form a macro variable, and a variable ratio coefficient speed regulation strategy for realizing the cooperative provision of frequency support by the wind turbine generators with different wind speeds is designed. And further forming a macro variable based on the linear combination of the frequency deviation, the energy storage frequency modulation power instruction and the virtual inertia of the wind generation set, and designing an additional frequency modulation active power regulation strategy for supporting the frequency, quickly recovering the MPPT operation of the wind generation set and avoiding the secondary disturbance of the frequency by cooperating the flywheel energy storage with the wind generation set. The invention has good robustness, simple control structure and easy engineering realization, can realize the frequency modulation response function of the wind storage system to the power grid, and reduces the active power regulation speed requirement of the synchronous generator participating in frequency modulation.

Description

Frequency modulation method of wind storage system based on double-layer cooperative control
Technical Field
The invention relates to a frequency modulation control method of a wind storage system, in particular to a control method for cooperative cooperation of a plurality of fans in a wind power plant in a frequency change process and a frequency supporting effect of the stored energy and the fans in the process.
Background
When the wind turbine generator is operated by utilizing a power electronic device in a grid-connected mode, the kinetic energy of a rotor of the wind turbine generator is decoupled from the frequency of a power grid in a Maximum Power Point Tracking (MPPT) operation mode, and a rotary inertia support cannot be provided for frequency change when the frequency of the power grid is disturbed. With the increase of the wind power grid-connected scale, the system rotational inertia can also continuously decrease, so that the research on friendly frequency support control of the wind turbine generator has important significance for improving the frequency dynamic stability of the wind power grid-connected system.
The existing control method for the wind turbine generator to participate in frequency support control mainly has two modes: the method comprises a frequency modulation control strategy based on the load shedding operation of the wind turbine generator and a frequency support control strategy based on the kinetic energy adjustment of a rotor of the wind turbine generator. The load reduction operation of the fan comprises two modes of overspeed load reduction and variable pitch load reduction, although the load reduction operation can enable the wind turbine generator to have the inertia and frequency modulation response capability at the same time, and the output power is not lower than the initial value before response in the frequency modulation period, the method enables the wind turbine generator to abandon the maximum power tracking operation mode when the frequency is normal, and the wind turbine resource cannot be fully utilized. The adjustment of the rotor kinetic energy of the wind turbine generator to the frequency support control is based on the adjustment of the generator control strategy, the rotor kinetic energy implied by the adjustment is utilized to respond to the frequency change of the system, the disturbance support effect of the wind turbine generator on the system frequency is realized from the excavation of the self frequency modulation capability of the wind turbine generator, and the operation economy is better. Common frequency support methods based on rotor kinetic energy of a wind turbine generator mainly include virtual inertia control, droop control, pitch angle control and the like.
In recent years, the energy storage technology is rapidly developed, and a research for improving the wind power digestion capability by utilizing energy storage is also developed by considering the random fluctuation of the wind power output power, the quick response capability and the high-power handling characteristic of the energy storage device. The energy storage device has a rapid power response characteristic, so that the frequency stability of the wind power access system can be effectively improved by utilizing the energy storage device to assist the wind power plant frequency support control, and the method has a good application prospect. At present, frequency modulation response research based on a wind storage system is also paid more attention at home and abroad.
The existing wind storage system frequency modulation response control research generally equates a wind power plant to a single fan, and frequency support coordination among wind power plants with different wind speeds is not considered. The wind power plant is often composed of dozens of wind power generation sets or even hundreds of wind power generation sets, the wind power generation sets are inconsistent in operation condition and strong in dynamic coupling, the wind power generation sets are mutually influenced in the inertia response process, and the inertia response of the wind power plant is a coordination control problem of a distributed multi-wind power generation set. Although the frequency disturbance of all wind turbines in the wind power plant is the same, the operation states of the turbines are different, and the kinetic energy of the rotor for inertia compensation is different. And the power instruction of the energy storage frequency modulation is only related to the system frequency and the change rate thereof, and because the change of the frequency supporting power of the wind turbine generator can influence the frequency recovery and even possibly cause the secondary drop of the frequency, a method for providing frequency modulation control by the cooperative coordination of a plurality of wind turbines and the energy storage in the wind power plant needs to be further researched in the energy storage frequency modulation process.
On the basis of analyzing feasibility of maximum power tracking operation wind turbine generator speed regulation by using variable scale coefficients and realizing frequency support of flywheel energy storage based on power regulation, a two-layer cooperative control scheme for providing frequency modulation response by running the wind turbine generator with the flywheel energy storage in cooperation with MPPT is provided on the basis of optimizing dynamic frequency response characteristics of a wind storage system and a cooperative control theory. The method comprises the steps that a macro variable is formed by linearly combining frequency deviation and virtual electrical inertia of a wind generation set responding to frequency disturbance, and a variable ratio coefficient control strategy for realizing cooperative frequency support of the wind generation sets with different wind speeds is designed by utilizing a manifold with the macro variable equal to zero and zero input response of the manifold. The method is characterized in that a linear combination energy storage frequency modulation power instruction and a wind turbine generator are adopted to realize a macro variable of cooperative frequency support and the same macro variable control flow, and an additional frequency modulation control strategy for providing frequency support, rapidly recovering MPPT operation of the wind turbine generator and avoiding secondary frequency disturbance by the energy storage cooperative wind turbine generator is designed. And finally, verifying the effectiveness of the provided cooperative control by using the load frequency disturbance of the wind power grid-connected system, wherein the result shows that the strategy is beneficial to improving the synchronous stable dynamic characteristic of the system and reducing the requirement on the frequency modulation power change speed of the synchronous generator.
Disclosure of Invention
The technical problem of the invention is mainly solved by the following technical scheme:
a frequency modulation method of a wind storage system based on double-layer cooperative control is characterized in that cooperation among different fans in a wind farm and cooperation between stored energy and the wind farm are achieved by respectively controlling a wind turbine generator and the stored energy, specifically speaking, the frequency modulation method is based on double-layer cooperative control
An inner layer cooperative control strategy for fan speed regulation based on variable scale coefficients: multiplying a proportional coefficient by a rotating speed reference instruction curve for realizing the maximum power tracking of the fan, and correcting the rotating speed reference instruction of the wind turbine generator through the cooperative control of the proportional coefficient to adjust the rotating speed when the system frequency is disturbed and changed, so as to realize providing frequency inertia support for the system based on the rotor kinetic energy adjustment; defining a wind field with n in total1Firstly, determining the ratio of the virtual electrical inertia of the wind turbine generator to the mechanical inertia of a shaft system at the current moment by adopting a formula I,
Figure BDA0002566572790000031
in the formula I, alphaiIs the ratio of the current virtual electrical inertia of the ith wind turbine in the wind power plant to the inherent mechanical inertia of the shafting, omegaeIs the synchronous electrical angular frequency, Δ ω, of the grideIs the deviation of the synchronous electrical angular frequency from its nominal value, n1Is the number of the fans in the wind field,
Figure BDA0002566572790000032
is the rate of change, P, of deviation of the synchronous electrical angular frequency from its nominal valuewm,iAnd Pws,iInput mechanical power and stator output electromagnetic power of the ith fan, Jw,iAnd Jw,lThe inherent mechanical inertia of shafting, omega, of the ith fan and the ith fan respectivelyr,lIs the rotor speed, t, of the first fan0Is the initial moment of the disturbance,
Figure BDA0002566572790000033
is t0The rotor speed of the first fan at the moment,
Figure BDA0002566572790000034
is t0The system synchronous electrical angular frequency at the moment, beta and T are all cooperative control parameters, wherein beta is a weight coefficient of a synchronous electrical angular frequency deviation amount in a macro variable designed according to a cooperative principle, and T is a time constant for the macro variable to converge from an initial state to a control manifold;
according to the ratio of the virtual electrical inertia to the shafting mechanical inertia determined by the formula I, the formula II is adopted to carry out variable ratio coefficient speed regulation control of the frequency inertia support provided by the wind turbine generator,
Figure BDA0002566572790000041
in the second formula, the first and second groups are,
Figure BDA0002566572790000042
and
Figure BDA0002566572790000043
respectively, the disturbance initial time t0K is a proportionality coefficient for adjusting a maximum power tracking curve;
the outer layer cooperative control method of flywheel energy storage frequency modulation response comprises the following steps: the three-mode type flywheel energy storage frequency support cooperative control is adopted,
Figure BDA0002566572790000044
in the formula III,. DELTA.PESSAnd
Figure BDA0002566572790000045
respectively the stored energy frequency-modulated power and its rate of change, omegaeAnd
Figure BDA0002566572790000046
respectively a system synchronous electrical angleFrequency and rate of change thereof, Δ ωeIs the deviation of the current synchronous electrical angular frequency from its nominal value, n1Is the number of fans in the wind field, alphaiIs the ratio of the virtual electric inertia to the inherent mechanical inertia of the ith fan calculated by the formula I, Pwm,iAnd Pws,iInput mechanical power and stator output electromagnetic power of the ith fan, Jw,iIs the inherent mechanical inertia of the axis of the i-th fan, beta1The parameter is a cooperative control parameter and represents a weight coefficient of the energy storage power variation in the macro variable, and the meanings of the beta parameter and the T parameter are the same as the formula I;
the control method specifically comprises the following steps:
step 1, detecting power grid frequency disturbance, and detecting the frequency disturbance of a grid-connected power system of a wind storage system;
step 2, when frequency disturbance occurs to a power grid, acquiring system frequency at the current moment, input mechanical power of each fan and output electromagnetic power value of a stator, calculating a ratio alpha of virtual electrical inertia and mechanical inertia of each wind generation set represented by a formula I according to known initial electrical synchronization angular frequency and inherent mechanical inertia of the fans, and further calculating a variable ratio coefficient k of wind generation set speed regulation according to a formula II; meanwhile, the power instruction value of the energy storage of the flywheel is calculated according to the formula III;
step 3, the rotating speed controller of the wind turbine generator adjusts the maximum power tracking curve according to k, so that the reference value omega of the rotating speed of the rotorrefChanging the kinetic energy of the fan rotor into k times when the control is not added;
step 4, the flywheel energy storage adjusts the rotation speed of the flywheel according to the formula IV according to the power instruction value, so that the flywheel energy storage releases or absorbs corresponding power when the frequency changes, and a frequency supporting effect is achieved;
Figure BDA0002566572790000051
wherein, ω isf0Indicating flywheel speed, P, at the moment of initiation of the disturbancerefAnd (4) obtaining the flywheel energy storage power reference value in the step (2).
In the frequency modulation method based on double-layer cooperative control for the wind storage system, in the inner-layer cooperative control strategy of the variable-scale-coefficient-based speed regulation of the fans, the inner-layer cooperative control is used for controlling the fans in the wind field according to the P of each fanwm,iAnd Pws,iDetermining alpha of each wind turbine generator by utilizing cooperative controliSo that the maximum power tracking operation unit at different operation wind speeds realizes cooperative frequency inertia support based on rotor kinetic energy adjustment by using a variable scale coefficient k; the formula I is formed by setting the theory of cooperative control
Figure BDA0002566572790000052
Macro variable of (1), solving
Figure BDA0002566572790000053
Wherein β represents a weight coefficient of the deviation amount of the synchronous electrical angular frequency, and T represents a convergence time constant of the macro variable from an initial state toward the control manifold; when the frequency deviation is constant, the larger the beta value is, the larger the deviation amount delta omega of the synchronous electrical angular frequencyeIn macro variables
Figure BDA0002566572790000061
The larger the occupied proportion is, the larger the virtual electric inertia of the fan is forced to be generated by cooperative control, so that more rotor kinetic energy is released to provide frequency inertia support, and therefore the value of beta is larger when parameters are selected; the T parameter determines the time for the macro variable to converge to the manifold, and the value of the T parameter is far shorter than the dynamic response time of the controlled system.
In the frequency modulation method based on double-layer cooperative control of the wind energy storage system, the outer layer cooperative control strategy of the energy storage participating in frequency modulation shown in the formula III, the outer layer cooperative control is realized by determining an additional frequency modulation power instruction delta P of flywheel energy storageESSTherefore, the frequency modulation response of the flywheel energy storage device based on real-time active power regulation is realized, and the maximum power tracking operation of each wind turbine generator is rapidly recovered after the wind power plant is supported by the frequency; the formula III is formed by setting the theory of cooperative control
Figure BDA0002566572790000062
Macro variable of (1), solving
Figure BDA0002566572790000063
Is derived from the control manifold, beta1Reflects the regulating capacity of the energy storage power to the frequency change, beta1The smaller the active power released or absorbed by the stored energy upon a change in frequency for the frequency-modulated response, and therefore beta1Should take a reasonably small value; in the energy storage frequency modulation control strategy, the additional frequency modulation power is not only related to the system frequency, but also related to the virtual electrical inertia and the output power of each fan in the wind field; therefore, in the frequency recovery process, although the output power of the wind generation sets is reduced and the maximum power tracking operation is recovered, the extra requirement of frequency modulation active power can be added to the power grid, the outer layer cooperative control can correspondingly adjust the energy storage output power according to the change of the output power of the wind power plant, and the maximum power tracking operation of each wind generation set is rapidly recovered while the frequency response dynamic characteristic is improved.
Therefore, the invention has the following advantages: the method for realizing the frequency support of the wind turbine generator based on variable ratio coefficient speed regulation has the advantages of control robustness, simple control structure and easy engineering realization. The wind turbine generator set at different wind speeds can generate different virtual inertias according to the kinetic energy of the rotor of the wind turbine generator set, and the purpose of supporting the multiple fans in a cooperative frequency mode is achieved. The energy storage can coordinate with the fan, and the wind turbine generator system provides frequency support in coordination, through the control to energy storage output, can resume wind turbine generator system MPPT operation more fast, avoids frequency secondary disturbance. Meanwhile, the strategy is beneficial to improving the synchronous stable dynamic characteristic of the system and reducing the requirement on the change of the frequency modulation power of the synchronous generator.
Drawings
FIG. 1 shows a frequency support control scheme of MPPT operation wind turbine generator system based on variable ratio coefficient speed regulation.
Fig. 2 is a frequency response control schematic diagram of flywheel energy storage.
Fig. 3 is a double-layer cooperative control scheme of the frequency response of the wind storage system.
FIG. 4 is a topological structure diagram of an improved IEEE-9 node wind storage system.
FIG. 5a is a fuzzy membership function with frequency deviation as input based on FFC and L-F control.
FIG. 5b is a fuzzy membership function with wind speed as input based on FFC and L-F control.
FIG. 5c is a fuzzy membership function based on FFC and L-F control outputs.
Fig. 6 is a schematic diagram of an energy storage power control strategy based on FFC and L-F control.
FIG. 7 is the response of the system frequency to sudden load change under different frequency support control of the wind storage system.
FIG. 8 shows wind turbine generator set output power under different frequency support control of the wind storage system.
FIG. 9 is a rotation speed response of a wind turbine under different frequency support control.
Fig. 10 shows the output power of the wind energy storage system under different frequency support control.
FIG. 11 shows the rotation speed of flywheel energy storage under different frequency support control of the wind energy storage system.
FIG. 12 shows the output response of the synchronous generator under different frequency modulation control of the wind storage system.
Detailed Description
The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.
The theoretical basis and method to which the present invention relates will be described in turn.
1. And detecting the frequency disturbance of the power grid, and detecting the frequency disturbance of the grid-connected power system of the doubly-fed wind turbine generator.
The grid frequency disturbance is detected according to the inequality shown below.
|fs,t-fe|≥ε2 (1)
Figure BDA0002566572790000081
fs,tRepresenting the grid frequency at time t; f. ofeRepresenting the rated frequency of the power grid; epsilon1And ε2Is a comparison threshold of grid frequency increment and rate of frequency change for initiating frequency support control. Considering that the allowable frequency deviation is +/-0.2 Hz for systems with the capacity of 3000MW and above in China and +/-0.5 Hz for systems with the capacity of below 3000MW, in order to avoid the frequency fluctuation from triggering the inertia control by mistake, when the per unit value is adopted for control calculation, the threshold value epsilon is set1＝ε2And 0.01, namely when the change rate of the grid frequency is larger than 0.5Hz/s or the change amount of the grid frequency is larger than 0.5Hz (the default grid rated frequency is 50Hz), the wind generation set and the energy storage set start the frequency support control. In addition, the time scale of the system frequency modulation control is considered to be in the second order.
2. Feasibility analysis for realizing frequency support of wind turbine generator based on rotation speed regulation
The doubly-fed wind turbine generator system utilizes a doubly-fed induction generator (DFIG) rotor side back-to-back voltage source type converter to input captured wind energy into a power grid. In order to fully utilize wind energy resources, a Maximum Power Point Tracking (MPPT) operation mode is generally adopted. Fig. 1 illustrates the speed control principle of MPPT operating doubly-fed wind turbine. In the figure, feIs the grid frequency rating. ρ represents the air density. Cp(lambda, beta) is the wind energy utilization coefficient, and is determined by the fan speed omegarAnd determining parameters such as wind speed v, blade pitch angle beta and impeller radius R. PwmAnd TmRespectively representing the mechanical power and the torque of the shafting of the wind turbine generator. PwsAnd TeRepresenting the stator active and electromagnetic torque of the doubly fed induction generator, respectively. D and HwRespectively representing the mechanical damping coefficient and the inertia time constant of the rotor shafting. OmegarminAnd ωrmaxAnd respectively representing the lowest rotating speed and the highest rotating speed of the grid-connected operation of the wind turbine generator. Omegaref、TrefAnd PrefAnd respectively representing the rotating speed, the electromagnetic torque and the reference value of the active work of the stator of the wind turbine generator. Omegaref＝aPs 2+bPs+ c is MPPT curve function, and coefficients a, b and c can utilize maximum P of different wind speedssAnd corresponds to omegarDetermined by fitting. The state variable X in the state equation is d and q axis currents of the stator and the rotor, i.e. isq，isd，irqAnd ird(ii) a The control inputs being selectable for the d and q-axis voltages of the stator and rotor of the generator, i.e. usq，usd，urqAnd urdThe coefficient matrices a and B are determined in accordance with the motor and control parameters.
As can be seen, the MPPT rotation speed control is to utilize P under the condition of unchanging the pitch anglewsTo PrefIs tracked to make omegarTends to let Cp(λ, β) reaches the maximum corresponding rotational speed. When the torque damping term of the fan shafting is neglected, the torque damping term is integrated with the shafting torque motion equation in the delta t period, and the torque damping term can be obtained,
Figure BDA0002566572790000091
in the formula, HwAnd representing the inertia time constant of the rotor shafting of the wind turbine generator. Δ ωrIndicating that the rotating speed of the wind turbine generator is at the regulation starting moment t0And an end time t1The amount of change in (c). The following formulas (1) and (2) are combined: when Δ PLWhen > 0, will be omega r,t0 is reduced by delta omega from the MPPT speed at the initial momentrIf, if
Figure BDA0002566572790000092
(ΔωrLess than or equal to 0), P will be added to the wind turbinewsTherefore, the frequency of the power grid can be reduced in cooperation with the damping of the synchronous generator; when Δ PLLess than 0, due to the increase of the fan speed to make HwΔωr(2ωr,t0+Δωr)＞0(Δωr> 0), the wind turbine will decrease PwsThereby being capable of cooperating with the frequency rise of the damping system of the synchronous generator. Based on the above analysis, the present document proposes a speed control strategy for dynamically adjusting a scaling coefficient k by a wind turbine generator according to a frequency deviation. By utilizing the strategy, when the high-proportion wind power grid-connected system generates frequency disturbance, the supporting effect of utilizing the kinetic energy of the fan rotor to damp frequency change is realized by adjusting the rotating speed instruction value of the wind turbine generator.
3. Flywheel energy storage real-time power regulation based frequency modulation response
The working principle of flywheel energy storage is to combine the rotor of the motor with the flywheel, to drive the flywheel to rotate at high speed by the motor, to convert the electric energy into mechanical energy for storage, when the electric energy is needed, the flywheel decelerates and drives the motor, the motor operates as a generator, to convert the kinetic energy of the flywheel into electric energy. A permanent magnet Brushless DC motor (BLDCM) is usually selected as a motor connected to a flywheel because it has the characteristics of convenient speed regulation, simple structure and high power density. FIG. 2 is a schematic diagram of a dual closed-loop PWM control system using BLDCM for flywheel energy storage.
As shown, the outer loop speed regulator regulates the power command P based on the stored energyfrefDetermining a reference value omega for the rotational speed of a flywheelfrefAnd using it as BLDCM armature current control inner ring iBLThereby generating a reference input u for the armature voltageBLrefThe reference input is compared with a carrier signal of pulse width modulation, and the reference input is used for generating a pulse width modulation signal of a motor stator side converter to control the on-off of a power electronic switch, and the armature voltage of the motor is modulated through the converter, so that the closed-loop control of the motor speed is realized. And considering the control time scale of the FESS participating in frequency modulation, the control of the back-to-back converter also adopts an average value model of the double-fed wind turbine generator.
The speed of the flywheel is increased and decreased to determine the storage and release of electric energy, so that the output power of the flywheel energy storage can be indirectly controlled by controlling the rotating speed of the rotating flywheel. Energy storage t with flywheel0The rotational speed at the moment is ωf0To t, for1Flywheel energy storage energy E can be obtained by integrating output power at momentfIn order to realize the purpose,
Figure BDA0002566572790000101
in the formula, JfIs the moment of inertia of the flywheel. Incorporating expressions of kinetic energy stored in high-speed flywheel
Figure BDA0002566572790000102
The relation between the rotational speed and the regulation active reference value can be obtained as follows,
Figure BDA0002566572790000103
in the formula, ωfmaxAnd ωfminRespectively, the upper and lower limit values of the flywheel rotational speed. The formula (5) shows that the reference value of the rotating speed can be adjusted from the initial time omega of the speed regulationf0And the integral of the active power reference value at the ending moment is determined together, so that the flywheel energy storage output power can be adjusted to reach a specified value by controlling the rotating speed reference value. Based on this, Δ P in the figures is presented hereinESSModifying P by adding the control component based on the control scheme of the frequency deviationfrefThe flywheel can release or absorb power when the frequency changes, active power shortage of the system is reduced, and the flywheel and the wind turbine generator jointly realize frequency supporting effect.
4. Cooperative control strategy for wind storage system
4.1 cooperative control of variable ratio coefficient speed regulation of wind turbine generator
When mechanical loss of the rotor shaft system of the wind turbine generator is neglected, the motion equation of the rotor shaft system of the wind turbine generator can be expressed as
Figure BDA0002566572790000104
In the formula, JwIs the rotational inertia of a rotor shaft system of the wind turbine generator and is equal to 2Hw. Suppose the virtual inertia of the electrical angular frequency of the wind turbine controlled by the additional inertia support shown in FIG. 2 is JeThen, as can be seen from the conservation of energy in the same time,
Figure BDA0002566572790000111
in the formula, t represents the current time. Then JeAnd omegarAnd ωeThe relationship of (a) is that,
Figure BDA0002566572790000112
let Je/Jwα, then from equation (8) it can be determined that the scaling factor k in fig. 2 is,
Figure BDA0002566572790000113
the formula (9) shows that the wind turbine generator can provide frequency support by adjusting the rotating speed through the dynamic electrical inertia coefficient alpha. Considering that each fan may be in different operation wind speeds in the frequency supporting process, the kinetic energy stored by the rotor is different, so that when the frequency changes, each fan releases corresponding kinetic energy according to the working condition of the fan to provide cooperative frequency support. In consideration of the characteristic that a wind power plant is composed of a plurality of fans, the electric virtual inertia and frequency deviation linear combination of the wind generation sets is used as a macro variable, and an inner layer cooperative control strategy for variable-proportion-coefficient speed regulation of the fans is designed by applying a cooperative control theory. Therefore, each wind turbine generator can release kinetic energy according to the magnitude of the kinetic energy, and the situation that the rotating speed is not deeply adjusted is avoided, the kinetic energy of the rotor is released in a coordinated mode, and the change amplitude of the frequency is damped.
Cooperative control is a state space control method developed based on synergetics and self-organization theory. Let there be a non-linear system dx/dt ═ f (x, u, t), where x is the state variable, u is the control input, and t is time. The method is implemented by defining macro variables
Figure BDA0002566572790000114
By making use of
Figure BDA0002566572790000115
Operating with zero manifold as control target under control, and based on
Figure BDA0002566572790000116
Constraining
Figure BDA0002566572790000117
Dynamic processes that tend to be popular, substituting macrovariate differential expressions in homogeneous differential equations for constraints, respectively
Figure BDA0002566572790000118
And a system state equation to solve the control law of u. In the above control, the macro-variables of the manifold
Figure BDA0002566572790000119
It is generally possible to set a linear combination of state variables, i.e.
Figure BDA00025665727900001110
Wherein beta isiRepresenting a macro variable
Figure BDA00025665727900001111
The directions of the components of the target position are approached on the manifold.
If the wind field has n1And (3) constructing the macro variable shown in the formula (10) by the typhoon generator set according to the cooperative control theory.
Figure BDA0002566572790000121
Where the greater β, the greater the virtual electrical inertia that the wind farm will provide as the frequency changes.
Derivation and substitution of macrovariables
Figure BDA0002566572790000122
It is possible to obtain,
Figure BDA0002566572790000123
obtainable according to the formulae (6) and (7),
Figure BDA0002566572790000124
further, J can be obtainedeThe derivative(s) of the signal(s),
Figure BDA0002566572790000125
the (13) is brought into (11) to obtain each fan alphaiThe control law of (1) is as follows:
Figure BDA0002566572790000126
the expression (14) comprises two expressions, wherein the former expression represents the total virtual inertia provided by the wind power plant, the latter expression represents the sum of the virtual inertia of the wind power generation sets except the ith wind power generation set, and the two expressions are subtracted and divided by the mechanical inertia of the ith wind power generation set to obtain alphaiThe control law of (2). Since Δ ω is at the beginning of the frequency decreaseeAnd
Figure BDA0002566572790000127
larger and wind turbine generator output power PwsGreater than input power P at rotor kinetic energy releasewmTherefore, as can be seen from the previous expression, the virtual inertia of the wind power plant is large, so that the unit can quickly release a large amount of kinetic energy. And in the frequency recovery phase, with the value of delta omegaeAnd
Figure BDA0002566572790000128
decrease of PwsGradually decreases and approaches PwmThe virtual inertia will also decrease. The adjusting characteristic enables the wind turbine generator to adjust the virtual electric inertia in a self-adaptive mode according to the change of the frequency deviation. The latter item shows that the second item control component of the low-speed unit is larger because the rotating speed adjusting range of the unit with higher rotating speed is larger during frequency supporting, so that the alpha of the low-speed unit is reduced. And different alpha enables the rotating speed of the wind turbine generator set to change differently in the frequency supporting process, so that the wind turbine generator sets with different wind speeds can provide cooperative virtual inertia support based on different rotor kinetic energies.
4.2 cooperative control of flywheel energy storage frequency modulation response
The dynamic process analysis of frequency support provided for the wind turbine generator is known, and the relation between the requirement of the wind turbine generator for additional active frequency modulation of the power grid and the adjustment of the input wind power and the rotor kinetic energy of the wind turbine generator can be described by an equation (15).
Figure BDA0002566572790000131
In the formula,. DELTA.PfgIndicating the extra fm active demand of the grid. Because the wind energy utilization coefficient can be reduced along with the deviation of the rotating speed of the fan from the MPPT optimal rotating speed, in the rotating speed adjusting process, when the input wind energy descending amplitude is larger than the kinetic energy released by the rotor, the output power of the unit is reduced to be smaller than the disturbance initial moment value, and therefore the requirement of power grid frequency modulation active is increased. Meanwhile, the unit can absorb active power from the power grid along with frequency recovery under speed regulation control to recover the MPPT operation rotating speed of the unit, so that the requirement of power grid frequency modulation active power is increased. When the synchronous generator cannot make delta P due to the limitation of active regulation speedfgWhen the equality constraint is satisfied, the synchronous generator will be forced to release its rotor kinetic energy to satisfy the equality constraint, which in turn results in a second order disturbance of the system frequency.
Starting from the aspects of utilizing energy storage rapid power regulation to respond to the wind turbine generator output active power change so as to provide frequency support, rapidly recovering the MPPT operation mode of the wind turbine generator and avoiding frequency secondary disturbance, respectively considering each wind turbine generator and energy storage as subsystems of a wind storage system, and utilizing FESS additional frequency modulation active power delta PESSThe virtual inertia and system frequency deviation of each wind turbine generator are linearly combined to construct a macro variable shown in an equation (16),
Figure BDA0002566572790000132
the macrovariable is derived and substituted into a homogeneous differential equation for constraining manifold dynamics to obtain,
Figure BDA0002566572790000133
the (13) is carried into the (17), the cooperative control rule of the stored energy additional frequency modulation power instruction can be obtained,
Figure BDA0002566572790000134
the energy storage device adjusts the power reference direction to set the input as positive and the output as negative. Equation (18) shows that the additional modulated frequency power is related not only to the system frequency, but also to the virtual inertia and output power of each wind turbine in the wind farm. Therefore, in the frequency recovery process, although the wind turbine generator output power is reduced and the MPPT operation mode is recovered, the extra requirement of frequency modulation active power can be added to the power grid, the outer layer cooperative control can correspondingly adjust the energy storage output power according to the change of the wind power plant output power, and the MPPT operation mode of each wind turbine generator is rapidly recovered while the frequency response dynamic characteristic is improved.
4. Simulation verification of wind power system based on IEEE-9 node
And (3) establishing an improved IEEE-9 node model of the wind storage grid-connected network shown in the figure 4 by utilizing Matlab/Simulink. In the model, each wind turbine of the wind field is subjected to equivalent wind turbine modeling by adopting a single-machine characterization method according to the same wind speed, and is respectively equivalent to three wind turbines with the wind speeds of 11m/s, 10m/s and 9 m/s. The three loads L1, L2, and L3 were 0.5+ j0.15pu, 0.3+ j0.1pu, and 0.4+ j0.2pu, respectively (reference capacity of 100 MVA). In the simulation, the wind turbine is set to be in MPPT operation, and because wind power is easier to reduce than wind power to increase, the load frequency disturbance for simulation is increased by 0.2p.u. active load at L3 by 5.0s to simulate the frequency reduction condition.
In order to verify the effectiveness of the double-layer cooperative control of the frequency response of the researched wind storage system, the comparative simulation research of the system frequency disturbance is carried out on the basis of three conditions of no frequency response of the wind storage system, double-layer cooperative control, variable ratio coefficient speed regulation of the wind turbine generator and load-frequency (L-F) control (wind storage frequency modulation control based on FFC and L-F for short) respectively. In simulation, FFC control input delta f of wind turbine generatorsThe argument of (1) is { -0.2, -0.167, -0.133, -0.1, -0.067, -0.033, 0}, the argument of controlling the input wind speed is {8.5, 9, 9.5, 10, 10.5, 11, 11.5}, and the control output is alpha }iHas a domain of {0, 2, 4, 6, 8, 10, 12}, and adopts a gravity center method to controlAnd (5) output de-fuzzification. The fuzzy membership function of input and output is shown in figure 5, the fuzzy inference rule is shown in table 1, and the schematic diagram of energy storage L-F control is shown in figure 6.
TABLE 1 fuzzy logic inference table
Figure BDA0002566572790000141
Figure BDA0002566572790000151
Figure 7 shows the comparison of the dynamic response of the frequency under the control of three frequency modulations of the wind storage system. The result shows that the wind storage system can provide better frequency support for power grid frequency disturbance by adopting frequency modulation control, and the double-layer cooperative control can more effectively increase the lowest point of frequency drop from 49.87Hz to about 49.88Hz compared with FFC and L-F-based frequency modulation control. Also, under the action of cooperative control, the frequency recovery stabilizing process has better dynamic characteristics.
The comparison simulation results of fig. 8 and fig. 9 show that compared with FFC and L-F based wind storage frequency modulation control, the double-layer cooperative control can provide virtual inertia support by adjusting the kinetic energy of the rotor of the wind turbine more quickly at the initial stage of frequency disturbance. In the frequency recovery stage, compared with the rotating speed recovery time of the wind turbine generator set under the action of two frequency response control shown in the figure 9, the rotor kinetic energy regulation state of the wind turbine generator set can be switched more quickly through cooperative control, so that the requirement of the rotor kinetic energy of the wind turbine generator set for virtual inertia support is reduced, and the wind turbine generator set has the characteristics of quickly storing the rotor kinetic energy and recovering the initial MPPT operation by reducing the output power more greatly under the support of the energy storage additional frequency modulation power and the synchronous generator frequency modulation power. Meanwhile, simulation results also show that the variable ratio coefficient speed regulation can realize that wind turbines with different wind speeds can provide corresponding frequency support according to the kinetic energy of the wind turbines.
The simulation comparison of fig. 10 and fig. 11 shows that compared with the frequency modulation control based on the FFC and the L-F, the double-layer cooperative control enables the energy storage cooperative wind power plant virtual inertia to output larger frequency modulation power at the initial frequency disturbance, and gradually reduces the output power as the wind power plant virtual inertia support is enhanced. In the frequency recovery stage, the output frequency modulation active power can be increased again to help the wind power plant to recover the MPPT operation, the extra active power requirement for the power grid frequency modulation caused by the rotating speed recovery of the wind turbine generator is reduced, and when the frequency is prevented from generating secondary disturbance, the synchronous generator is assisted to rapidly recover the frequency stability.
Fig. 12 compares the fm output responses of the synchronous generators G1 and G2 under two wind storage fm controls. As can be seen, in the virtual inertia supporting stage of the two frequency modulation controls, the output power of the wind storage system is increased, so that the increased frequency modulation output power of G1 and G2 is obviously reduced compared with the control without frequency response. As can be seen from fig. 10 and fig. 11, the double-layer cooperative control enables the stored energy to output larger frequency modulation power in the frequency recovery stage, so that the MPPT operation of the wind turbine generator can be recovered more quickly, and the variation range of the frequency modulation output power of G1 and G2 is smaller than that of the frequency modulation control based on the FFC and L-F. And the comparison of the dynamic changes of the power angle difference between G1 and G2 also shows that the double-layer cooperative control has the characteristic of improving the synchronous stable dynamic characteristic of the system.
The specific embodiments described in this application are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims (3)

1. A frequency modulation method of a wind storage system based on double-layer cooperative control is characterized in that cooperation among different fans in a wind farm and cooperation between stored energy and the wind farm are achieved by respectively controlling a wind turbine generator and the stored energy, specifically speaking, the frequency modulation method is based on double-layer cooperative control
An inner layer cooperative control strategy for fan speed regulation based on variable scale coefficients: the method is characterized in that a proportional coefficient is multiplied by a rotating speed reference instruction curve for realizing the maximum power tracking of the fan, and when the frequency of the system is disturbed and changed, the rotating speed reference instruction of the wind turbine generator is corrected through the cooperative control of the proportional coefficient to adjust the rotating speed reference instructionSpeed, so that the purpose of providing frequency inertia support for the system based on rotor kinetic energy adjustment is achieved; defining a wind field with n in total1Firstly, determining the ratio of the virtual electrical inertia of the wind turbine generator to the mechanical inertia of a shaft system at the current moment by adopting a formula I,
Figure FDA0003394516560000011
in the formula I, alphaiIs the ratio of the current virtual electrical inertia of the ith wind turbine in the wind power plant to the inherent mechanical inertia of the shafting, omegaeIs the synchronous electrical angular frequency, Δ ω, of the grideIs the deviation of the synchronous electrical angular frequency from its nominal value, n1Is the number of the fans in the wind field,
Figure FDA0003394516560000012
is the rate of change, P, of deviation of the synchronous electrical angular frequency from its nominal valuewm,iAnd Pws,iInput mechanical power and stator output electromagnetic power of the ith fan, Jw,iAnd Jw,lThe inherent mechanical inertia of shafting, omega, of the ith fan and the ith fan respectivelyr,lIs the rotor speed, t, of the first fan0Is the initial moment of the disturbance,
Figure FDA0003394516560000013
is t0The rotor speed of the first fan at the moment,
Figure FDA0003394516560000014
is t0The system synchronous electrical angular frequency at the moment, beta and T are all cooperative control parameters, wherein beta is a weight coefficient of a synchronous electrical angular frequency deviation amount in a macro variable designed according to a cooperative principle, and T is a time constant for the macro variable to converge from an initial state to a control manifold;
according to the ratio of the virtual electrical inertia to the shafting mechanical inertia determined by the formula I, the formula II is adopted to carry out variable ratio coefficient speed regulation control of the frequency inertia support provided by the wind turbine generator,
Figure FDA0003394516560000015
in the second formula, the first and second groups are,
Figure FDA0003394516560000016
and
Figure FDA0003394516560000017
respectively, the disturbance initial time t0K is a proportionality coefficient for adjusting a maximum power tracking curve;
the outer layer cooperative control method of flywheel energy storage frequency modulation response comprises the following steps: the three-mode type flywheel energy storage frequency support cooperative control is adopted,
Figure FDA0003394516560000021
in the formula III,. DELTA.PESSAnd
Figure FDA0003394516560000022
respectively the stored energy frequency-modulated power and its rate of change, omegaeAnd
Figure FDA0003394516560000023
respectively, the system synchronous electrical angular frequency and its rate of change, Δ ωeIs the deviation of the current synchronous electrical angular frequency from its nominal value, n1Is the number of fans in the wind field, alphaiIs the ratio of the virtual electric inertia to the inherent mechanical inertia of the ith fan calculated by the formula I, Pwm,iAnd Pws,iInput mechanical power and stator output electromagnetic power of the ith fan, Jw,iIs the inherent mechanical inertia of the axis of the i-th fan, beta1The parameter is a cooperative control parameter and represents a weight coefficient of the energy storage power variation in the macro variable, and the meanings of the beta parameter and the T parameter are the same as the formula I;
the control method specifically comprises the following steps:
step 1, detecting power grid frequency disturbance, and detecting the frequency disturbance of a grid-connected power system of a wind storage system;
step 2, when frequency disturbance occurs to the power grid, acquiring the system frequency at the current moment, the input mechanical power of each fan and the output electromagnetic power value of the stator, and calculating the ratio alpha of the virtual electrical inertia to the mechanical inertia of each wind turbine expressed by the formula I according to the known initial electrical synchronization angular frequency and the inherent mechanical inertia of the faniFurther, a variable ratio coefficient k of the wind turbine generator speed regulation is obtained according to the formula II; meanwhile, the power instruction value of the energy storage of the flywheel is calculated according to the formula III;
step 3, the rotating speed controller of the wind turbine generator adjusts the maximum power tracking curve according to k, so that the reference value omega of the rotating speed of the rotorrefChanging the kinetic energy of the fan rotor into k times when the control is not added;
step 4, the flywheel energy storage adjusts the rotation speed of the flywheel according to the formula IV according to the power instruction value, so that the flywheel energy storage releases or absorbs corresponding power when the frequency changes, and a frequency supporting effect is achieved;
Figure FDA0003394516560000024
wherein, ω isf0Indicating flywheel speed, P, at the moment of initiation of the disturbancerefAnd (4) obtaining the flywheel energy storage power reference value in the step (2).
2. The double-layer cooperative control-based frequency modulation method for the wind storage system according to claim 1, wherein in an inner-layer cooperative control strategy for speed regulation of the fans based on variable scale coefficients, the inner-layer cooperative control is used for controlling the fans in the wind field according to P of the fanswm,iAnd Pws,iDetermining alpha of each wind turbine generator by utilizing cooperative controliSo that the maximum power tracking operation unit at different operation wind speeds realizes cooperative frequency inertia support based on rotor kinetic energy adjustment by using a variable scale coefficient k; formula one is determined by the cooperative control theoryIs shaped like
Figure FDA0003394516560000031
Macro variable of (1), solving
Figure FDA0003394516560000032
Wherein β represents a weight coefficient of the deviation amount of the synchronous electrical angular frequency, and T represents a convergence time constant of the macro variable from an initial state toward the control manifold; when the frequency deviation is constant, the larger the beta value is, the larger the deviation amount delta omega of the synchronous electrical angular frequencyeIn macro variables
Figure FDA0003394516560000033
The larger the occupied proportion is, the larger the virtual electric inertia of the fan is forced to be generated by cooperative control, so that more rotor kinetic energy is released to provide frequency inertia support, and therefore the value of beta is larger when parameters are selected; the T parameter determines the time for the macro variable to converge to the manifold, and the value of the T parameter is less than the dynamic response time of the controlled system.
3. The frequency modulation method of the wind energy storage system based on the double-layer cooperative control as claimed in claim 1, wherein in the outer layer cooperative control strategy of the energy storage participation frequency modulation shown in formula III, the outer layer cooperative control is realized by determining an additional frequency modulation power command Δ P of the flywheel energy storageESSTherefore, the frequency modulation response of the flywheel energy storage device based on real-time active power regulation is realized, and the maximum power tracking operation of each wind turbine generator is rapidly recovered after the wind power plant is supported by the frequency; the formula III is formed by setting the theory of cooperative control
Figure FDA0003394516560000034
Macro variable of (1), solving
Figure FDA0003394516560000035
Is derived from the control manifold, beta1Reflects the regulating capacity of the energy storage power to the frequency change, beta1The smaller the energy is stored at the frequencyThe greater the active power released or absorbed for the frequency modulated response at a rate change, and therefore beta1Should take a reasonably small value; in the energy storage frequency modulation control strategy, the additional frequency modulation power is not only related to the system frequency, but also related to the virtual electrical inertia and the output power of each fan in the wind field; therefore, in the frequency recovery process, although the output power of the wind generation sets is reduced and the maximum power tracking operation is recovered, the extra requirement of frequency modulation active power can be added to the power grid, the outer layer cooperative control can correspondingly adjust the energy storage output power according to the change of the output power of the wind power plant, and the maximum power tracking operation of each wind generation set is rapidly recovered while the frequency response dynamic characteristic is improved.
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