CN115313443A - Frequency modulation state transfer control method based on energy storage virtual inertia requirement - Google Patents

Frequency modulation state transfer control method based on energy storage virtual inertia requirement Download PDF

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CN115313443A
CN115313443A CN202211026832.1A CN202211026832A CN115313443A CN 115313443 A CN115313443 A CN 115313443A CN 202211026832 A CN202211026832 A CN 202211026832A CN 115313443 A CN115313443 A CN 115313443A
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energy storage
inertia
frequency modulation
capacity
time constant
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付媛
万怿
张祥宇
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North China Electric Power University
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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
    • H02J3/28—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
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • 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
    • 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
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • 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

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Abstract

The invention discloses a frequency modulation state transfer control method based on energy storage virtual inertia requirements, which comprises the following steps: when the stored energy participates in the frequency modulation of the power system through additional inertia control, calculating the virtual inertia time constant of the stored energy in the frequency conversion extreme value time of the system; calculating the percentage of the capacity of the energy storage to be configured to the capacity of the fan according to the minimum inertia requirement of the system; providing state transfer control of energy storage, enabling the output force to be stably transited to the synchronous machine side after the support of the energy storage inertia is finished, and ensuring that sufficient charge state is reserved in the energy storage to participate in next frequency modulation; and the size of the control parameter of the frequency modulation state transfer is designed, so that the energy storage exit effect is ensured to be optimal. The frequency modulation state transfer control method based on the energy storage virtual inertia requirement provided by the invention can ensure stable exit after the energy storage inertia support is finished and ensure the stability of the system frequency.

Description

Frequency modulation state transfer control method based on energy storage virtual inertia requirement
Technical Field
The invention relates to the technical field of power generation system control, in particular to a frequency modulation state transfer control method based on energy storage virtual inertia requirements.
Background
The new energy has intermittence due to self power, and is suitable for being used as an auxiliary power supply for maintaining the stability of a system. Under the condition of high wind and light penetration, energy storage must be added to ensure the stability maintaining capability of the system after the conventional unit is replaced. In a new power system, the grid-connected active support function of the energy storage device has been paid much attention at present. Because the energy storage equipment is not only flexibly controlled, but also has long-time (2-3 hours of discharge) energy storage, the energy storage equipment completely has the capability of quickly supporting the system frequency for a long time, and therefore, a frequency modulation state transfer control method based on the energy storage virtual inertia requirement is urgently needed, a new control mode for exerting the energy storage grid-connected support characteristic is formed, the inertia and primary frequency modulation control mode of a fan and a synchronous machine is further broken through, and a technical support is provided for remarkably improving the operation stability of new energy power generation.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention aims to provide a frequency modulation state transfer control method based on energy storage virtual inertia requirements, which calculates the configuration requirement of energy storage under the condition of meeting the minimum inertia requirement of a system by calculating the virtual inertia of energy storage within frequency conversion extreme value time; by providing frequency modulation state transfer control, the output of the energy storage is gradually transited to the synchronous machine side by withdrawing the energy storage in a grading way, reasonable dereferencing of frequency modulation state transfer control parameters is ensured to maintain the system frequency within a frequency safety range, and meanwhile, sufficient charge state is reserved for the energy storage so that the energy storage can participate in the next frequency modulation process of the system.
In order to achieve the technical purpose, the invention provides a frequency modulation state transfer control method based on energy storage virtual inertia requirements, which comprises the following steps:
acquiring a virtual inertia time constant of an energy storage system, wherein the energy storage system is applied to a wind power generation system, and the wind power generation system also comprises a fan and a synchronous machine;
acquiring the percentage of the capacity of the configured energy storage system in the capacity of the fan based on the minimum inertia requirement of the power system;
and performing frequency modulation state transfer control on the energy storage system according to the virtual inertia time constant and the percentage, wherein the frequency modulation state transfer control is used for stably transitioning the output of the energy storage system to the side of the synchronous machine after the energy storage inertia supporting is finished, and ensuring that the energy storage system has a charge state participating in the next frequency modulation.
Preferably, in the process of acquiring the virtual inertia time constant of the energy storage system, when the energy storage system participates in frequency modulation of the power system through additional inertia control, the virtual inertia time constant is calculated within the frequency conversion extremum time of the power system.
Preferably, in the process of calculating the virtual inertia time constant, the power system frequency conversion extreme value time t fm Expressed as:
Figure BDA0003815909750000021
in the formula, each parameter can be represented as:
Figure BDA0003815909750000022
Figure BDA0003815909750000023
Figure BDA0003815909750000024
wherein H S Is the system inertial time constant; d is a system damping coefficient; k is L Adjusting the coefficient for the system load; sigma is a synchronous machine adjustment coefficient; t is g Is the turbine equivalent time constant of inertia; a is a turbine characteristic coefficient; k is a radical of 1 Is the wind power permeability.
Preferably, in calculating the virtual inertia time constant, the virtual inertia time constant H B Expressed as:
Figure BDA0003815909750000031
in the formula,. DELTA.P B Supporting power for energy storage inertia, and configuring capacity k with maximum value of energy storage 1 k 2 Wherein k is 1 Wind power permeability; k is a radical of 2 The ratio of the energy storage capacity to the fan capacity, ω 0 And ω 1 Respectively, initial angular frequency and t fm The angular frequency corresponding to the time instant.
Preferably, in the process of obtaining the ratio of the capacity of the energy storage system to the capacity of the fan, when the energy storage system participates in the frequency modulation of the power system through additional inertia control, an inertia time constant of the power system is obtained;
acquiring the percentage of the capacity of the energy storage system in the capacity of the fan based on the minimum inertia requirement of the power system;
preferably, in the process of acquiring the inertia time constant, the inertia time constant is expressed as:
Figure BDA0003815909750000032
wherein H G And H w Inertia time constants of the synchronous machine and the fan are respectively; s G And S w Respectively the installed capacities of the synchronous machine and the fan; s. the N Is the total installed capacity of the system.
Preferably, under the condition based on the minimum inertia requirement of the power system, the percentage of the capacity of the energy storage system in the capacity of the fan is obtained as follows:
Figure BDA0003815909750000033
preferably, in the process of performing frequency modulation state transfer control on the energy storage system, a transfer function for frequency modulation state transfer control is set;
according to the transfer function, acquiring an image function of unit step response of the energy storage system, and performing inverse Laplace transformation, wherein the expression for frequency modulation state transition control is acquired as follows:
Figure BDA0003815909750000041
wherein-e -t/T Is a transient component.
Preferably, in the process of acquiring the transfer function and the image function, the transfer function is expressed as:
Figure BDA0003815909750000042
the objective function is expressed as:
Figure BDA0003815909750000043
wherein T is the time constant of the frequency modulation state transition control, and s is a complex variable.
Preferably, the fm state transition control system for implementing the fm state transition control method includes:
the virtual inertia time constant generation module is used for acquiring a virtual inertia time constant of an energy storage system, wherein the energy storage system is applied to a wind power generation system, and the wind power generation system further comprises a fan and a synchronous fan;
the energy storage capacity ratio module is used for acquiring the percentage of the capacity of the configured energy storage system in the capacity of the fan based on the minimum inertia requirement of the power system;
and the frequency modulation state control module is used for performing frequency modulation state transfer control on the energy storage system according to the virtual inertia time constant and the percentage, and is used for stably transitioning the output of the energy storage system to the side of the synchronous machine after the energy storage inertia supporting is finished, so that the energy storage system is ensured to have a charge state participating in the next frequency modulation.
The invention discloses the following technical effects:
compared with the traditional control method, the invention breaks through the inertia and primary frequency modulation control modes of the fan and the synchronous machine, and researches a new control mode suitable for exerting the energy storage grid-connected support characteristic. Under the currently generally adopted virtual inertia control, the new energy power can play a role in quickly supporting in the initial stage of disturbance, and after the frequency drop amplitude reaches the maximum, the supporting capacity is lost, and instead, the power support is requested from the system in the frequency recovery period. Calculating the virtual inertia of energy storage within the time of the frequency conversion extreme value, and calculating the configuration requirement of energy storage under the condition of meeting the minimum inertia requirement of a system; and (3) providing frequency modulation state transfer control, wherein the output force is gradually transited to the synchronous machine side by the energy storage through graded exit, and reasonable value of frequency modulation state transfer control parameters ensures that the system frequency is maintained in a frequency safety range, and simultaneously, sufficient charge state is reserved for the energy storage to participate in the next frequency modulation process of the system.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a method for controlling frequency modulation state transition based on energy storage virtual inertia requirements according to the present invention;
FIG. 2 is a diagram of a frequency response model of the system according to the present invention;
FIG. 3 is a block diagram of state transition control according to the present invention;
FIG. 4 is a unit step response curve for the FM state transition control of the present invention;
FIG. 5 is a schematic diagram of the energy storage staging exit process according to the present invention;
FIG. 6 is a diagram of a 3-machine 9-node system simulation topology according to the present invention;
FIG. 7 is a graph comparing the frequency change of the first and second exits controlled by the energy storage state transition according to the present invention;
fig. 8 is a comparison graph of different values and effects of the transfer control parameters of the energy storage state transfer control frequency modulation state according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.
As shown in fig. 1 to 8, the present invention obtains the configuration requirement of energy storage by calculating the virtual inertia of energy storage within the time of frequency conversion extremum, and under the condition of satisfying the minimum inertia requirement of the system; and then, frequency modulation state transfer control is provided, the output force is gradually transited to the synchronous machine side by the energy storage through graded quitting, the reasonable value of the frequency modulation state transfer control parameter ensures that the system frequency is maintained in a frequency safety range, and meanwhile, sufficient charge state is reserved for the energy storage to participate in the next frequency modulation process of the system.
As shown in fig. 1, the frequency modulation state transition control method based on the energy storage virtual inertia requirement, provided by the invention, comprises the following steps:
step 1: when the stored energy participates in the frequency modulation of the power system through additional inertia control, calculating the virtual inertia time constant of the stored energy in the frequency conversion extreme value time of the system;
step 2: calculating the percentage of the capacity of the energy storage to be configured to the capacity of the fan according to the minimum inertia requirement of the system;
and 3, step 3: providing state transfer control of energy storage, enabling the output force to be stably transited to the synchronous machine side after the support of the energy storage inertia is finished, and ensuring that sufficient charge state is reserved in the energy storage to participate in next frequency modulation;
and 4, step 4: and the size of a frequency modulation state transfer control parameter is designed to ensure that the energy storage exit effect is optimal.
Fig. 2 is a diagram of a frequency response model of the system according to the present invention.
The frequency response dynamic equation of the grid-connected system with wind storage can be expressed as
Figure BDA0003815909750000071
In the formula,. DELTA.P m A power response for the synchronizer; delta P B Responding to the stored energy power; delta P L Is a load power response; h s Is the system inertia time constant.
Calculating the system frequency variation, expressed as
Figure BDA0003815909750000072
The inverse Laplace transform and derivation can obtain the frequency fall time of the system as follows:
Figure BDA0003815909750000081
wherein each parameter can be expressed as
Figure BDA0003815909750000082
Figure BDA0003815909750000083
Figure BDA0003815909750000084
Wherein H S Is the system inertia time constant; d is a system damping coefficient; k is L Adjusting the coefficient for the system load; sigma is a synchronous machine adjustment coefficient; t is g Is the turbine equivalent time constant of inertia; a is a turbine characteristicA coefficient; k is a radical of 1 Is the wind power permeability.
Defining the system frequency falling time t fm Is the frequency conversion extreme value time.
The data values in the table 1 are substituted into the above formula to calculate the frequency conversion extreme value time t fm The size of (2).
TABLE 1
Figure BDA0003815909750000085
Substituting data to obtain frequency conversion extreme value time t fm ＝2.3s。
When the stored energy participates in the frequency modulation of the power system through the additional inertia control, in this mode, the stored energy dynamic equation with virtual inertia can be expressed as:
Figure BDA0003815909750000086
in the formula, T m And T e The energy storage is virtualized to be mechanical torque and electromagnetic torque after the synchronous machine.
Multiplying both sides of the equation by the angular frequency ω at the same time and in [0,t fm ]And integrating in a time period to obtain the virtual inertia provided by the stored energy for the system, wherein the virtual inertia is as follows:
Figure BDA0003815909750000091
in the formula,. DELTA.P B Supporting power for energy storage inertia, and configuring capacity k with maximum value of energy storage 1 k 2 Wherein k is 1 Wind power permeability; k is a radical of 2 The ratio of the energy storage capacity to the fan capacity is adopted.
According to the national power quality standard, the lower limit of the frequency allowable short-time operation of the power system is 48Hz. Within the range, the variation range of the angular frequency omega per unit value of the virtual synchronous machine is 0.96-1. The virtual inertia of the energy storage device after the energy storage additional inertia control can be evaluated by using the above formula, and the scheme is favorable for solving the problem of inertia dynamic evaluation which can be finished only by monitoring the energy storage charge state and the system frequency change in real time under differential control.
The installed capacity of the Fujian province network is taken as an example to calculate the size of the energy storage inertia time constant, and the installed capacity of each unit is shown in Table 2.
TABLE 2
Figure BDA0003815909750000092
Assuming that a fan is configured with 10% energy storage, S B =735MW, the energy storage capacity is about 1% of the total installed capacity, and the inertia support H provided by the system by the energy storage can be obtained by substituting the energy storage inertia time constant calculation formula B ＝0.29s。
When the wind reservoir participates in the frequency modulation of the power system through additional inertia control, the inertia time constant of the power system can be expressed as:
Figure BDA0003815909750000101
in the formula, H G And H w Inertia time constants of the synchronous machine and the fan are respectively; s. the G And S w Respectively the installed capacities of the synchronous machine and the fan; s N Is the total installed capacity of the system.
Substituting the magnitude of the virtual inertia time constant of the stored energy into the above equation can obtain:
Figure BDA0003815909750000102
as can be seen from the above formula, along with the increase of the proportion of the fan installation, the inertia of the system is reduced, and the frequency has instability risks. It is generally considered that the minimum inertia requirement H of the system S_min And 5s, when the inertia of the system is lower than 5s, the inertia of the system is considered to be insufficient, and energy storage is needed to provide inertia support for the system.
In order to further calculate the configuration requirements of the energy storage capacity under different wind power permeabilities, the configuration requirements can be obtained by deforming a system inertia magnitude calculation formula, and the condition that the assembly proportional relation of the energy storage and the wind power needs to meet the requirement is
Figure BDA0003815909750000103
The energy storage capacity required to be configured under different fan permeability can be calculated by the formula on the premise of ensuring that the system meets the minimum inertia requirement, so that the synchronous machine and the energy storage jointly provide enough inertia support for the system, the frequency stability of the system is ensured, and the calculation result is shown in table 3.
TABLE 3
Figure BDA0003815909750000104
The wind and storage capacity configuration must meet the minimum inertia requirement of the system. The inertia time constant of a conventional synchronous generator is typically 5-10 s. At present, the energy storage allocation principle of each provincial company is about 10% -15% of the installed capacity of the fan.
Fig. 3 is a state transition control block diagram. A state transition judgment link and a first-order inertia controller are added in the energy storage frequency modulation controller. And judging whether a state transition link needs to be entered or not according to whether the frequency recovers a steady state or not. The frequency modulation state transfer link is divided into a first-level exit and a second-level exit, and the judgment is carried out according to whether the size of the energy storage allowed exit capacity exceeds the configuration capacity of the energy storage. The first-order inertia link is used for delaying the exit speed of stored energy, and the system frequency is prevented from rapidly changing and greatly falling or lifting.
Fig. 4 is a unit step response curve for frequency modulated state transition control.
The transfer function of the additional FM state transition control is expressed as
Figure BDA0003815909750000111
In the formula, T is referred to as a time constant of the fm state transition control.
The performance index of the FM state transition control time response is closely related to T. When the input is unit step response, namely R (t) =1 (t), R(s) =1/s, so the image function of the unit step response of the system is
Figure BDA0003815909750000112
By performing an inverse Ralski transformation on F(s), then
Figure BDA0003815909750000113
In the formula, -e -t/T Is a transient component.
During the energy storage exit process, the expression of the frequency modulation state transfer control is defined as
Figure BDA0003815909750000114
Fig. 5 is a schematic diagram of an energy storage stage exit process, and whether the energy storage first-stage exit or second-stage exit is determined according to whether the size of the energy storage allowable exit capacity exceeds the configuration capacity of the energy storage, where the specific determination method is as follows:
under the constraint of the maximum frequency change rate of the system, the maximum power change when the stored energy exits is as follows:
Figure BDA0003815909750000121
the maximum frequency change rate of the system is 0.5Hz/s; when the permeability is 60%, the energy storage configuration capacity k 1 k 2 And =0.06pu, as can be seen from the above equation, the maximum value of the power change when the energy storage exits is 0.048pu, and the maximum value of the power change when the energy storage exits is smaller than the configured capacity of the energy storage, so that the energy storage needs to take a secondary exit, otherwise, the frequency change rate exceeds the system allowable value. During the frequency modulation state transition, when the maximum allowable energy storage power change value exceeds the configured capacity of the energy storage,the stored energy can also be directly withdrawn.
As shown in FIG. 6, the invention is a 3-machine 9-node system simulation topology structure diagram, the system comprises a wind farm DFIG (300 2MW doubly-fed wind power generator sets) and corresponding energy storage (60 MW), and three thermal power plants (G) with capacities of 600MW, 500MW and 300MW respectively 1 、G 2 And G 3 ). The load L capacity is 300MW. The wind power generation permeability is 30%, and the wind power permeability can be changed by adjusting the capacities of the thermal power generating unit and the fan.
As shown in FIG. 6, the invention builds an IEEE 3 machine 9 node simulation system incorporated in a wind farm based on DIGSILENT/Power Factory simulation platform, the system comprises a wind farm DFIG (300 doubly-fed wind generating sets of 2 MW) and corresponding energy storage (60 MW), and three thermal Power plants (G) with capacities of 600MW, 500MW and 300MW respectively 1 、G 2 And G 3 ). The load L capacity is 300MW. The wind power generation permeability is 30%, and the wind power permeability can be changed by adjusting the capacities of the thermal power generating unit and the fan.
The control effect of the frequency modulation state transfer control method based on the energy storage virtual inertia requirement is verified by setting the following two control schemes, which shows that the invention can quit the output condition of the energy storage in stages through the frequency modulation state transfer control after the energy storage gives full play to the inertia supporting capability through a new control method, and the system frequency can not fluctuate too much in the energy storage state transfer process through the setting of the frequency modulation state transfer control parameters.
Scheme 1: when the energy storage adopts the state transfer control, the first-stage exit and the second-stage exit are respectively adopted to respectively observe the response condition of the system frequency, and the simulation result is shown in fig. 7;
scheme 2: when the energy storage adopts the state transfer control, the response conditions of the system frequency are respectively observed by setting different values of the frequency modulation state transfer control parameters, the frequency modulation state transfer control time parameters T are respectively set to be 0.1, 0.5 and 1, and the simulation result is shown in fig. 8.
And setting 10% of sudden load power increase as unbalanced power disturbance, respectively verifying the system frequency response conditions of the first scheme and the second scheme under the condition that the fan is configured with 10% of stored energy, and verifying the reasonability and effectiveness of the proposed state transfer control strategy.
FIG. 7 is a graph comparing the frequency change of the primary exit and the secondary exit under the control of the energy storage state transition proposed by the present invention. As shown in fig. 7, when the wind power permeability is 60%, if the stored energy is completely exited once, the frequency change rate of the system reaches 0.55Hz/s, and it is not guaranteed that the frequency is stabilized within 0.5Hz/s, which will cause adverse effects on the system. Therefore, energy storage staging exits are required in the case of high wind power permeability. When the energy storage is withdrawn in two stages, the maximum frequency change rate of the system is reduced to 0.29Hz/s when the energy storage is withdrawn in each stage, the fluctuation range of the system frequency is met, and the necessity of system state transition and energy storage stage withdrawal is verified.
Fig. 8 is a comparison graph of different values and effects of the transfer control parameters of the energy storage state transfer control frequency modulation state according to the present invention.
After a first-order inertia link is added in the frequency modulation state transfer process, when the time reaches 4T, the energy storage completes a quitting process. If the energy storage multi-level exit is carried out under the condition that the frequency is not stable within the frequency conversion extreme value time, the frequency change rate of the system is easily caused to exceed a critical value, so the action time of frequency modulation state transfer control is not less than the frequency conversion extreme value time. However, if the tuning of the fm state transition control time parameter is too large, the energy storage exit process will be slow, causing long-term frequency fluctuation, and not conducive to fast frequency recovery. Therefore, the action time of the frequency modulation state transition control is set to be the frequency conversion extreme value time, namely T = T fm /4。
In the first step, the time of the frequency conversion extreme value is calculated to be t fm And =2.3s, i.e. T =0.575 is an optimal value. As can be seen from fig. 8: when the frequency modulation state transition control parameter T =0.1, the maximum frequency change rate of the system reaches 0.56Hz/s and exceeds the maximum frequency change rate limit; when T =1s, the frequency change rate of the system is reduced to 0.22Hz/s, but the energy storage exit process is slow due to the fact that T is large in value, the frequency recovery process of the system is prolonged, and the frequency offset time is close to 20s. When T =0.5s, the frequency change rate of the system is 0.37Hz/s, the frequency offset time is about 10s, the frequency change rate can be ensured to meet the system requirement,but also can ensure the quick recovery of the frequency and verify the rationality of the parameter values. .
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

Claims (10)

1. A frequency modulation state transfer control method based on energy storage virtual inertia requirements is characterized by comprising the following steps:
acquiring a virtual inertia time constant of an energy storage system, wherein the energy storage system is applied to a wind power generation system, and the wind power generation system further comprises a fan and a synchronous machine;
acquiring the percentage of the capacity of the energy storage system in the capacity of the fan based on the minimum inertia requirement of the power system;
and performing frequency modulation state transfer control on the energy storage system according to the virtual inertia time constant and the percentage, and enabling the output of the energy storage system after the support of the energy storage inertia is finished to be stably transited to the synchronous machine side, so that the energy storage system is ensured to have a charge state participating in the next frequency modulation.
2. A frequency modulation state transition control method based on energy storage virtual inertia demand according to claim 1, characterized in that:
in the process of obtaining the virtual inertia time constant of the energy storage system, when the energy storage system participates in the frequency modulation of the power system through additional inertia control, the virtual inertia time constant is calculated within the frequency conversion extreme value time of the power system.
3. A frequency modulation state transition control method based on energy storage virtual inertia demand according to claim 2, characterized in that:
in the process of calculating the virtual inertia time constant, the power system frequency conversion extreme value time t fm Expressed as:
Figure FDA0003815909740000011
in the formula, each parameter can be represented as:
Figure FDA0003815909740000021
Figure FDA0003815909740000022
Figure FDA0003815909740000023
wherein H S Is the system inertia time constant; d is a system damping coefficient; k L Adjusting the coefficient for the system load; sigma is a synchronous machine adjustment coefficient; t is g Is the turbine equivalent time constant of inertia; a is a turbine characteristic coefficient; k is a radical of 1 Is the wind power permeability.
4. A frequency modulation state transition control method based on energy storage virtual inertia demand according to claim 3, characterized in that:
in calculating the virtual inertia time constant, the virtual inertia time constant H B Expressed as:
Figure FDA0003815909740000024
in the formula,. DELTA.P B Supporting power for energy storage inertia, and configuring capacity k with maximum value of energy storage 1 k 2 Wherein k is 1 The wind power permeability is adopted; k is a radical of 2 The ratio of the energy storage capacity to the fan capacity, omega 0 And ω 1 Angular frequency of the initial time and t, respectively fm The angular frequency corresponding to the time instant.
5. A frequency modulation state transition control method based on an energy storage virtual inertia demand according to claim 4, characterized in that:
in the process of acquiring the ratio of the capacity of the energy storage system to the capacity of the fan, acquiring an inertia time constant of the power system when the energy storage system participates in the frequency modulation of the power system through additional inertia control;
and acquiring the percentage of the capacity of the energy storage system in the capacity of the fan based on the minimum inertia requirement of the power system.
6. A frequency modulation state transition control method based on an energy storage virtual inertia demand according to claim 5, characterized in that:
in obtaining the inertia time constant, the inertia time constant is expressed as:
Figure FDA0003815909740000031
wherein H G And H w Inertia time constants of the synchronous machine and the fan are respectively; s G And S w Respectively the installed capacities of the synchronous machine and the fan; s N Is the total installed capacity of the system.
7. A frequency modulation state transition control method based on an energy storage virtual inertia demand according to claim 6, characterized in that:
under the condition based on the minimum inertia requirement of the power system, acquiring the percentage of the capacity of the energy storage system in the fan capacity as follows:
Figure FDA0003815909740000032
8. a frequency modulation state transition control method based on energy storage virtual inertia demand according to claim 7, characterized in that:
in the process of carrying out frequency modulation state transfer control on the energy storage system, setting a transfer function for the frequency modulation state transfer control;
according to the transfer function, acquiring an image function of unit step response of the energy storage system, and performing inverse Laplace transformation, wherein the expression for frequency modulation state transition control is acquired as follows:
Figure FDA0003815909740000033
wherein-e -t/T Is a transient component.
9. A frequency modulation state transition control method based on energy storage virtual inertia demand according to claim 8, characterized in that:
in the process of acquiring the transfer function and the image function, the transfer function is expressed as:
Figure FDA0003815909740000041
the image function is represented as:
Figure FDA0003815909740000042
wherein T is the time constant of the frequency modulation state transfer control, and s is a complex variable.
10. A frequency modulation state transition control method based on energy storage virtual inertia demand according to claim 9, characterized in that:
a FM state transition control system for implementing a FM state transition control method, comprising:
the virtual inertia time constant generating module is used for acquiring a virtual inertia time constant of an energy storage system, wherein the energy storage system is applied to a wind power generation system, and the wind power generation system further comprises a fan and a synchronous machine;
the energy storage capacity ratio module is used for acquiring the percentage of the capacity of the configured energy storage system in the capacity of the fan based on the minimum inertia requirement of the power system;
and the frequency modulation state control module is used for carrying out frequency modulation state transfer control on the energy storage system according to the virtual inertia time constant and the percentage, and is used for stably transitioning the output magnitude of the energy storage system after the energy storage inertia supporting is finished to the synchronous machine side, so that the energy storage system is ensured to have a charge state participating in the next frequency modulation.
CN202211026832.1A 2022-08-25 2022-08-25 Frequency modulation state transfer control method based on energy storage virtual inertia requirement Pending CN115313443A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116706944A (en) * 2023-08-07 2023-09-05 昆明理工大学 Method for determining new energy permeability under frequency safety constraint
CN117477605A (en) * 2023-12-27 2024-01-30 山东大学 New energy hysteresis inertia control method cooperated with primary frequency modulation response of synchronous machine

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116706944A (en) * 2023-08-07 2023-09-05 昆明理工大学 Method for determining new energy permeability under frequency safety constraint
CN116706944B (en) * 2023-08-07 2023-10-27 昆明理工大学 Method for determining new energy permeability under frequency safety constraint
CN117477605A (en) * 2023-12-27 2024-01-30 山东大学 New energy hysteresis inertia control method cooperated with primary frequency modulation response of synchronous machine
CN117477605B (en) * 2023-12-27 2024-04-02 山东大学 New energy hysteresis inertia control method cooperated with primary frequency modulation response of synchronous machine

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