CN117439124A - Method for improving power grid frequency by adopting energy storage system and related device - Google Patents
Method for improving power grid frequency by adopting energy storage system and related device Download PDFInfo
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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
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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
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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
- H02J3/30—Arrangements for balancing of the load in a network by storage of energy using dynamo-electric machines coupled to flywheels
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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
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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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
- H02J3/38—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
- H02J3/48—Controlling the sharing of the in-phase component
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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
- H02J3/38—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
- H02J3/50—Controlling the sharing of the out-of-phase component
-
- 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
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
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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
- 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
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- 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
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Abstract
The invention provides a method for improving power grid frequency by adopting an energy storage system and a related device. The energy storage system comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier and an inverter, and the method comprises the following steps: and respectively controlling the energy storage converter and the inverter by adopting a VSG control method so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the frequency of the power grid. According to the method, the characteristic that the flywheel energy storage module is a rotating system and the response speed is high is considered, and the defect that the response speed of the photovoltaic energy storage VSG of the non-rotating system is low is compensated through the VSG control of the flywheel energy storage module corresponding to the inverter, so that virtual inertia is provided for a power grid together, and the stability of the frequency of the power grid is improved.
Description
Technical Field
The invention relates to the technical field of energy storage systems, in particular to a method for improving power grid frequency by adopting an energy storage system and a related device.
Background
The synchronous generator provides a large amount of mechanical inertia for the power grid, can be coupled with the power grid in a natural synchronous way, participates in the regulation of the voltage and the frequency of the power grid, and can provide enough rotary spare capacity to compensate the system power loss when the power system fails. The grid-connected proportion of the photovoltaic energy storage system is continuously improved, and the proportion of the synchronous generator in the power system is also reduced.
In order to make up for the deficiency of voltage and frequency regulation capability brought by optical storage grid connection, the prior art generally adopts a VSG (Virtual Synchronous Generator ) to embed algorithms such as a rotor motion equation, reactive droop control and the like of the synchronous generator into an inversion control system, and when a power grid suffers faults or interference, the distributed power generation of the inversion control system is regulated, so that the working characteristics similar to the synchronous generator are realized. Although the optical storage VSG can increase virtual inertia for the power grid, the response speed is low, and the stability of the power system is not improved well.
Disclosure of Invention
The embodiment of the invention provides a method and a related device for improving the frequency of a power grid by adopting an energy storage system, which are used for solving the problem that the stability improvement effect of the existing light storage VSG on the power system is poor.
In a first aspect, an embodiment of the present invention provides a method for improving a grid frequency using an energy storage system, the energy storage system including a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, and an inverter; the target energy storage module is connected with a power grid bus through the energy storage converter, and the flywheel energy storage module is connected with the power grid bus through the rectifier and the inverter in sequence;
the method comprises the following steps:
and respectively controlling the energy storage converter and the inverter by adopting a VSG control method so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the frequency of the power grid.
In a second aspect, an embodiment of the present invention provides an apparatus for improving a grid frequency using an energy storage system, the energy storage system including a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, and an inverter; the target energy storage module is connected with a power grid bus through the energy storage converter, and the flywheel energy storage module is connected with the power grid bus through the rectifier and the inverter in sequence;
the device comprises:
and the VSG control module is used for respectively controlling the energy storage converter and the inverter by adopting a VSG control method so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the power grid frequency.
In a third aspect, an embodiment of the present invention provides a terminal, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor executes the computer program to implement the steps of the method for improving a grid frequency using an energy storage system according to any one of the possible implementations of the first aspect above.
In a fourth aspect, embodiments of the present invention provide a computer readable storage medium storing a computer program which, when executed by a processor, implements the steps of a method of improving grid frequency using an energy storage system as described in any one of the possible implementations of the first aspect above.
In a fifth aspect, embodiments of the present invention provide an energy storage system, which includes a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, an inverter, and a terminal as described in the third aspect above;
the target energy storage module is connected with a power grid bus through the energy storage converter, and the flywheel energy storage module is connected with the power grid bus through the rectifier and the inverter in sequence.
The embodiment of the invention provides a method and a related device for improving the frequency of a power grid by adopting an energy storage system, wherein the energy storage system comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier and an inverter, and the energy storage converter and the inverter are respectively controlled by adopting a VSG control method so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the frequency of the power grid. According to the method, the characteristic that the flywheel energy storage module is a rotating system and the response speed is high is considered, and the defect that the response speed of the photovoltaic energy storage VSG of the non-rotating system is low is compensated through the VSG control of the flywheel energy storage module corresponding to the inverter, so that virtual inertia is provided for a power grid together, and the stability of the frequency of the power grid is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an application scenario diagram of a method for improving grid frequency using an energy storage system according to an embodiment of the present invention;
FIG. 2 is a flowchart of a method for improving grid frequency using an energy storage system according to an embodiment of the present invention;
FIG. 3 is a flow chart of VSG control provided by an embodiment of the present invention;
FIG. 4 is a flowchart of SPWM signal generation provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram of an apparatus for improving grid frequency using an energy storage system according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a terminal according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the following description will be made by way of specific embodiments with reference to the accompanying drawings.
Fig. 1 is an application scenario diagram of a method for improving a grid frequency by using an energy storage system according to an embodiment of the present invention. As shown in fig. 1, the energy storage system includes a target energy storage module BAT, a flywheel energy storage module M (M1, M2,..and MN), an energy storage converter PCS (PCS 1, PCS2,..pcsn), a rectifier AC/DC, and an inverter DC/AC; the target energy storage module BAT is connected with a power grid bus through the energy storage converter PCS, and the flywheel energy storage module M is connected with the power grid bus through the rectifier AC/DC and the inverter DC/AC in sequence.
Specifically, the target energy storage module is an energy storage module except for the flywheel energy storage module, and specifically can comprise a photovoltaic energy storage module, a wind power energy storage module or an energy storage battery. The method provided in the present application will be described in detail below using a photovoltaic energy storage module as an example.
Referring to fig. 2, a flowchart of an implementation of a method for improving a grid frequency by using an energy storage system according to an embodiment of the present invention is shown in detail as follows:
s101: and respectively controlling the energy storage converter and the inverter by adopting a VSG control method so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the frequency of the power grid.
The execution main body of the embodiment is a control main body of the energy storage system, and the control main body is respectively in communication connection with a controller of the energy storage converter and a controller of the inverter, and is used for respectively sending virtual rotor inertia distribution instructions to the controller of the energy storage converter and the controller of the inverter, and the controller of the energy storage converter and the controller of the inverter perform corresponding VSG control on the corresponding circuits based on the respective received virtual rotor inertia distribution instructions, so that the energy storage converter VSG and the inverter VSG respectively output virtual rotor inertia corresponding to the corresponding virtual rotor inertia distribution instructions.
In this embodiment, the virtual synchronous machine technology is a technology that simulates the electromechanical transient characteristics of a synchronous machine set, so that a power supply or a load using a converter has external operation characteristics such as inertia, damping, frequency and voltage adjustment of the synchronous machine set. Because the photovoltaic energy storage system is a non-rotating system, the speed of the corresponding virtual synchronous generator responding to the change of the power grid frequency is slower, and therefore the power grid frequency cannot be adjusted timely when the power grid fluctuation is larger. In the primary frequency modulation control stage, the flywheel energy storage module is connected to the power grid, so that further fluctuation of the power grid is not caused, the defect of low response speed of the photovoltaic energy storage VSG of the non-rotating system can be compensated through VSG control of the flywheel energy storage inverter, and therefore virtual inertia is provided for the power grid by the flywheel energy storage VSG and the photovoltaic energy storage VSG when the fluctuation of the power grid frequency is large, and the power grid frequency is fast stabilized.
In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; the specific implementation flow of S101 includes:
setting the first virtual rotor inertia to a fixed value;
determining a second virtual rotor inertia based on the grid frequency adaptation;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
In one possible implementation, the specific implementation procedure for determining the virtual rotor inertia requirement value includes:
based on the formulaCalculating the second virtual rotor inertia;
wherein J represents the second virtual rotor inertia，J 0 Representing a virtual rotor inertia steady state value; ω represents the virtual rotor angular velocity of the inverter, ω g Represents the angular velocity of the power grid, and ω g ＝2πf g Wherein f g Representing the grid frequency, k representing a constant, and C representing a threshold value for the rate of change of the virtual rotor angular velocity.
Specifically, the magnitude of the virtual rotor inertia is determined by the difference between the virtual angular velocity of the VSG and the grid angular velocity, and the magnitude of the virtual angular velocity, and when the virtual angular velocity of the VSG is greater than the grid angular velocity and the virtual angular velocity of the VSG is greater than zero, the virtual rotor inertia increases, when the virtual angular velocity of the VSG is greater than the grid angular velocity and the virtual angular velocity of the VSG is less than zero, the virtual rotor inertia decreases, and when the virtual angular velocity of the VSG is less than the grid angular velocity and the virtual angular velocity of the VSG is less than zero, the virtual rotor inertia increases, and when the virtual angular velocity of the VSG is less than the grid angular velocity and the virtual angular velocity of the VSG is greater than zero. Based on the principle, the energy storage converter VSG/inverter VSG can adaptively output virtual rotor inertia with corresponding size based on the power grid frequency, so that the frequency response speed of the energy storage system is improved.
Wherein J is 0 Representing a steady state value of virtual rotor inertia, may be determined based on the natural vibration angular velocity of the synchronous generator.
As can be seen from the above embodiments, when the grid system is relatively stable, the present embodiment adopts the original target energy storage module to correspond to the VSG of the inverter to stabilize the grid frequency. When the fluctuation of the power grid frequency is large, the self-adaptive virtual rotor inertia-based method has the advantage of high response speed, and the flywheel energy storage system has the advantage of high response speed as a rotating system, and on the basis of the photovoltaic energy storage VSG, the flywheel energy storage is adopted to provide virtual rotor inertia for fine adjustment of the power grid frequency, so that the advantage of high response speed of the rotating system such as the flywheel energy storage VSG can be fully utilized, and a large-capacity flywheel energy storage module does not need to be configured.
In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; the specific implementation flow of S101 includes:
setting the second virtual rotor inertia to a fixed value;
determining the first virtual rotor inertia based on the grid frequency adaptation;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
According to the embodiment, fixed virtual rotor inertia can be distributed for the flywheel energy storage module corresponding to the inverter VSG, and the target energy storage module is enabled to provide virtual rotor inertia adaptive to power grid frequency change, so that the response speed of the flywheel energy storage module and the target energy storage module corresponding to the VSG is improved, and the power grid frequency stability is further improved.
Specifically, when the first virtual rotor inertia is adaptively determined based on the grid frequency, the formulaω is the virtual rotor angular velocity of the energy storage converter.
In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia;
the specific implementation flow of S101 includes:
acquiring second virtual rotor inertia corresponding to the inverter based on power grid frequency self-adaption;
if the second virtual rotor inertia is smaller than the maximum value of the first rotor inertia, setting the first virtual rotor inertia to be zero;
if the second virtual rotor inertia is equal to the maximum value of the first rotor inertia, the first virtual rotor inertia corresponding to the energy storage converter is obtained based on power grid frequency self-adaption;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
In particular, the present embodiment may preferentially use the virtual rotor inertia provided by the inverter VSG to provide support for the grid frequency, so as to improve the response speed. When the inverter VSG is insufficient to support the grid frequency, the energy storage converter is re-enabled to provide a virtual rotor inertia of the adaptive grid frequency. The magnitude of the virtual rotor angular velocity is positively correlated with the magnitude of the input power of the inverter, so that the maximum value of the first rotor inertia corresponding to the inverter is the virtual rotor inertia output when the maximum overload capacity of the inverter is reached.
In this embodiment, when the control host monitors that the second virtual rotor inertia is equal to the maximum value of the first rotor inertia within the duration of the first preset time period, or the number of sampling moments of the second virtual rotor inertia equal to the maximum value of the first rotor inertia within the second preset time period is equal to a preset percentage of the total number of sampling moments of the whole second preset time period, it is determined that the inverter cannot output virtual inertia enough to support the grid frequency, and then the first virtual rotor inertia corresponding to the energy storage converter is obtained based on the grid frequency in a self-adaptive manner.
Wherein, the preset percentage can be 60-80%.
In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; the specific implementation flow of S101 includes:
acquiring first virtual rotor inertia corresponding to the energy storage converter based on power grid frequency self-adaption;
if the first virtual rotor inertia is smaller than a second rotor inertia maximum value, setting the second virtual rotor inertia to zero;
if the first virtual rotor inertia is equal to the maximum value of the second rotor inertia, the second virtual rotor inertia corresponding to the energy storage converter is obtained based on power grid frequency self-adaption;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
Specifically, the embodiment can preferentially adopt the virtual rotor inertia provided by the energy storage converter to provide support for the power grid frequency, and when the energy storage converter VSG is insufficient to support the power grid frequency, the inverter is started to provide the virtual rotor inertia of the self-adaptive power grid frequency, so that the stability of the power grid frequency can be realized without configuring a large-capacity flywheel energy storage module. The magnitude of the virtual rotor angular velocity is positively correlated with the magnitude of the input power of the energy storage converter, so that the maximum value of the second rotor inertia corresponding to the energy storage converter is the virtual rotor inertia output when the energy storage converter has the maximum overload capacity.
In this embodiment, when the control host monitors that the first virtual rotor inertia continues for a first preset time period to be equal to the maximum value of the second rotor inertia, or that the number of control periods of the first virtual rotor inertia equal to the maximum value of the second rotor inertia in the second preset time period is a preset percentage of the total number of control periods of the whole second preset time period, it is determined that the energy storage converter cannot output virtual inertia enough to support the grid frequency, and then the second virtual rotor inertia corresponding to the inverter is obtained based on the grid frequency in a self-adaptive manner.
In one possible implementation manner, fig. 3 shows a control flow chart of the energy storage converter, and as shown in fig. 3, a specific implementation flow of VSG control of the energy storage converter by using the first virtual rotor inertia includes:
s201: the input voltage actual value U of the energy storage converter o Input reactive-voltage regulation loop, output given energy storage converter VSG voltage amplitude e a ,e b ,e c ；
S202: the input active power P of the energy storage converter is input into an active-frequency regulating loop, and the phase of VSG is outputWherein the first virtual rotor inertia is a parameter value in the active-frequency adjustment loop;
s203: based on a given energy storage converter VSG voltage amplitude e a ,e b ,e c And the phase of VSGAnd obtaining the three-phase given voltage of the energy storage converter VSG.
Specifically, the specific implementation flow of S201 includes:
obtaining an actual value U of an input voltage of the energy storage converter o ；
Rated value U of input voltage ref Subtracting the actual value of the input voltage U o Obtaining an input voltage error;
will give reactive power Q ref Subtracting the output reactive power Q of the energy storage converter after amplitude limiting to obtain a reactive power error;
input voltage error and voltage adjustment coefficient k v Multiplying to obtain a first control quantity; the reactive power error and the reactive power adjustment coefficient k q Multiplying to obtain a second control quantity;
the first control quantity, the second control quantity and the no-load electromotive force E of the energy storage converter VSG 0 Adding to obtain a given voltage amplitude e of the energy storage converter VSG a ,e b ,e c ；
Specifically, as shown in fig. 3, the specific implementation procedure of S202 includes:
will give active power P ref Subtracting the input active power P of the energy storage converter to obtain an active power difference value;
based on the formulaCalculating the virtual rotor angular velocity omega of the VSG; integrating the virtual rotor angular velocity omega of the VSG to obtain the phase +.>
Wherein omega 0 Represents the synchronous angular speed of the power grid, D represents the damping coefficient corresponding to the damping torque, T d Damping torque from mechanical friction, stator losses, excitation and damping windings.
In one possible implementation, the specific implementation procedure of S203 includes:
based on the formula
Calculating a three-phase given voltage of the energy storage converter VSG;
in the formula (1), e a Represents a given voltage of phase a, e b Represents a given voltage of phase b, e c Represents a given voltage of phase c, E p Representing the amplitude of the phase voltages, E represents the amplitude of the voltage of a given energy storage converter VSG,represents the phase of the VSG and ω represents the virtual rotor angular velocity.
In one possible implementation, fig. 4 shows a block diagram of the generation of an SPWM (Sinusoidal Pulse Width Modulation ) signal that controls an energy storage converter. As shown in fig. 4, after the three-phase given voltage of the energy storage converter is obtained, the three-phase given voltage is input into the control loop shown in fig. 4, and the SPWM signal is generated. In FIG. 4, i ref Representing nominal grid-tie current, i a 、i b And i c Respectively representing three-phase output currents; i.e e Representing the output current deviation; PR is a proportional resonant regulator (Proportional resonant regulator), L represents inductance, R represents local resistance, u m Representing the voltage amplitude of the modulated signal.
In this embodiment, after the sinusoidal pulse width modulation signal is obtained, each switching tube of the energy storage converter is controlled by adopting the sinusoidal pulse width modulation signal, so that the energy storage converter outputs a corresponding virtual rotor inertia.
Similarly, the VSG control and sinusoidal pulse width modulation signal generation of the inverter may also be implemented by using the control block diagrams shown in fig. 3 and 4, which are not described herein.
It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not limit the implementation process of the embodiment of the present invention.
The following are device embodiments of the invention, for details not described in detail therein, reference may be made to the corresponding method embodiments described above.
Fig. 5 is a schematic structural diagram of an apparatus for improving a grid frequency by using an energy storage system according to an embodiment of the present invention, and for convenience of explanation, only a portion related to the embodiment of the present invention is shown, which is described in detail below:
as shown in fig. 5, an apparatus 100 for improving a grid frequency using an energy storage system includes:
the VSG control module 110 is configured to control the energy storage converter and the inverter by using a VSG control method, so that the energy storage converter and the inverter together provide a virtual rotor inertia to maintain the stability of the grid frequency.
In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; the VSG control module 110 includes:
a first virtual rotor inertia obtaining unit configured to set the first virtual rotor inertia to a fixed value;
the second virtual rotor inertia obtaining unit is used for adaptively determining second virtual rotor inertia based on the power grid frequency;
and the VSG control unit is used for performing VSG control on the energy storage converter by adopting the first virtual rotor inertia and performing VSG control on the inverter by adopting the second virtual rotor inertia.
In one possible implementation manner, the second virtual rotor inertia obtaining unit includes:
based on the formulaCalculating the second virtual rotor inertia;
wherein J represents a second virtual rotor inertia, J 0 Representing a virtual rotor inertia steady state value; ω represents the virtual rotor angular velocity of the inverter, ω g Represents the angular velocity of the power grid, and ω g ＝2πf g Wherein f g Representing the grid frequency, k representing a constant, and C representing a threshold value for the rate of change of the virtual rotor angular velocity.
In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; the VSG control module 110 includes:
setting the second virtual rotor inertia to a fixed value;
determining the first virtual rotor inertia based on the grid frequency adaptation;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; the VSG control module 110 includes:
acquiring second virtual rotor inertia corresponding to the inverter based on power grid frequency self-adaption;
if the second virtual rotor inertia is smaller than the maximum value of the first rotor inertia, setting the first virtual rotor inertia to be zero;
if the second virtual rotor inertia is equal to the maximum value of the first rotor inertia, the first virtual rotor inertia corresponding to the energy storage converter is obtained based on power grid frequency self-adaption;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; the VSG control module 110 includes:
acquiring first virtual rotor inertia corresponding to the energy storage converter based on power grid frequency self-adaption;
if the first virtual rotor inertia is smaller than a second rotor inertia maximum value, setting the second virtual rotor inertia to zero;
if the first virtual rotor inertia is equal to the maximum value of the second rotor inertia, the second virtual rotor inertia corresponding to the energy storage converter is obtained based on power grid frequency self-adaption;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
According to the embodiment, the characteristics of high response speed of the flywheel energy storage module which is a rotating system are considered, and the disadvantage of low response speed of the photovoltaic energy storage of the non-rotating system is compensated by the VSG control of the flywheel energy storage module corresponding to the inverter, so that virtual inertia is provided for a power grid together, and the stability of the frequency of the power grid is improved.
Fig. 6 is a schematic diagram of a terminal according to an embodiment of the present invention. As shown in fig. 6, the terminal 6 of this embodiment includes: a processor 60 and a memory 61. The memory 61 is configured to store a computer program 62, and the processor 60 is configured to invoke and execute the computer program 62 stored in the memory 61, to perform the steps of the method embodiments described above for improving the grid frequency using an energy storage system, such as step 101 shown in fig. 2. Alternatively, the processor 60 is configured to invoke and run the computer program 62 stored in the memory 61 to implement the functions of the modules/units in the above-described device embodiments, such as the functions of the module 110 shown in fig. 5.
Illustratively, the computer program 62 may be partitioned into one or more modules/units that are stored in the memory 61 and executed by the processor 60 to complete the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing the specified functions, which instruction segments are used for describing the execution of the computer program 62 in the terminal 6.
The terminal 6 may be a computing device such as a desktop computer, a notebook computer, a palm computer, a cloud server, etc. The terminal 6 may include, but is not limited to, a processor 60, a memory 61. It will be appreciated by those skilled in the art that fig. 6 is merely an example of terminal 6 and is not intended to limit terminal 6, and may include more or fewer components than shown, or may combine certain components, or different components, e.g., the terminal may further include an input-output device, a network access device, a bus, etc.
The processor 60 may be a central processing unit (Central Processing Unit, CPU), other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), field-programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 61 may be an internal storage unit of the terminal 6, such as a hard disk or a memory of the terminal 6. The memory 61 may also be an external storage device of the terminal 6, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash Card (Flash Card) or the like, which are provided on the terminal 6. Further, the memory 61 may also include both an internal storage unit and an external storage device of the terminal 6. The memory 61 is used for storing the computer program and other programs and data required by the terminal. The memory 61 may also be used for temporarily storing data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working process of the units and modules in the above system may refer to the corresponding process in the foregoing method embodiment, which is not described herein again.
The embodiment of the invention provides an energy storage system, which comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, an inverter and a terminal as described above;
the target energy storage module is connected with a power grid bus through the energy storage converter, and the flywheel energy storage module is connected with the power grid bus through the rectifier and the inverter in sequence.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal and method may be implemented in other manners. For example, the apparatus/terminal embodiments described above are merely illustrative, e.g., the division of the modules or units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via interfaces, devices or units, which may be in electrical, mechanical or other forms.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated modules/units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present invention may also be implemented by implementing all or part of the above-described embodiment method, or by implementing the relevant hardware by a computer program, where the computer program may be stored in a computer readable storage medium, and the computer program may be executed by a processor, where the steps of each of the above-described embodiment method for improving the grid frequency by using an energy storage system are implemented. Wherein the computer program comprises computer program code which may be in source code form, object code form, executable file or some intermediate form etc. The computer readable medium may include: any entity or device capable of carrying the computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth. It should be noted that the computer readable medium may include content that is subject to appropriate increases and decreases as required by jurisdictions in which such content is subject to legislation and patent practice, such as in certain jurisdictions in which such content is not included as electrical carrier signals and telecommunication signals.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.
Claims (10)
1. A method for improving the frequency of a power grid by adopting an energy storage system, which is characterized in that the energy storage system comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier and an inverter; the target energy storage module is connected with a power grid bus through the energy storage converter, and the flywheel energy storage module is connected with the power grid bus through the rectifier and the inverter in sequence;
the method comprises the following steps:
and respectively controlling the energy storage converter and the inverter by adopting a VSG control method so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the frequency of the power grid.
2. The method of improving grid frequency with an energy storage system of claim 1, wherein the virtual rotor inertia comprises a first virtual rotor inertia and a second virtual rotor inertia;
the adoption of the VSG control method to respectively control the energy storage converter and the inverter so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the power grid frequency comprises the following steps:
setting the first virtual rotor inertia to a fixed value;
determining a second virtual rotor inertia based on the grid frequency adaptation;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
3. The method of improving grid frequency with an energy storage system of claim 2, wherein said adaptively determining a second virtual rotor inertia based on the grid frequency comprises:
based on the formulaCalculating the second virtual rotor inertia;
wherein J represents a second virtual rotor inertia, J 0 Representing a virtual rotor inertia steady state value; ω represents the virtual rotor angular velocity of the inverter, ω g Represents the angular velocity of the power grid, and ω g ＝2πf g Wherein f g Representing the grid frequency, k representing a constant, and C representing a threshold value for the rate of change of the virtual rotor angular velocity.
4. The method of improving grid frequency with an energy storage system of claim 1, wherein the virtual rotor inertia comprises a first virtual rotor inertia and a second virtual rotor inertia;
the adoption of the VSG control method to respectively control the energy storage converter and the inverter so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the power grid frequency comprises the following steps:
setting the second virtual rotor inertia to a fixed value;
determining the first virtual rotor inertia based on the grid frequency adaptation;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
5. The method of improving grid frequency with an energy storage system of claim 1, wherein the virtual rotor inertia comprises a first virtual rotor inertia and a second virtual rotor inertia;
the adoption of the VSG control method to respectively control the energy storage converter and the inverter so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the power grid frequency comprises the following steps:
acquiring second virtual rotor inertia corresponding to the inverter based on power grid frequency self-adaption;
if the second virtual rotor inertia is smaller than the maximum value of the first rotor inertia, setting the first virtual rotor inertia to be zero;
if the second virtual rotor inertia is equal to the maximum value of the first rotor inertia, the first virtual rotor inertia corresponding to the energy storage converter is obtained based on power grid frequency self-adaption;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
6. The method of improving grid frequency with an energy storage system of claim 5, wherein the virtual rotor inertia comprises a first virtual rotor inertia and a second virtual rotor inertia;
the adoption of the VSG control method to respectively control the energy storage converter and the inverter so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the power grid frequency comprises the following steps:
acquiring first virtual rotor inertia corresponding to the energy storage converter based on power grid frequency self-adaption;
if the first virtual rotor inertia is smaller than a second rotor inertia maximum value, setting the second virtual rotor inertia to zero;
if the first virtual rotor inertia is equal to the maximum value of the second rotor inertia, the second virtual rotor inertia corresponding to the energy storage converter is obtained based on power grid frequency self-adaption;
and performing VSG control on the energy storage converter by adopting the first virtual rotor inertia, and performing VSG control on the inverter by adopting the second virtual rotor inertia.
7. An apparatus for improving grid frequency using an energy storage system, comprising: the energy storage system comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier and an inverter; the target energy storage module is connected with a power grid bus through the energy storage converter, and the flywheel energy storage module is connected with the power grid bus through the rectifier and the inverter in sequence;
the device comprises:
and the VSG control module is used for respectively controlling the energy storage converter and the inverter by adopting a VSG control method so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the power grid frequency.
8. A terminal comprising a processor and a memory for storing a computer program, the processor for invoking and running the computer program stored in the memory to perform the method of improving grid frequency with an energy storage system according to any of claims 1 to 6.
9. A computer-readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the steps of the method for improving grid frequency with an energy storage system according to any one of the preceding claims 1 to 6.
10. An energy storage system comprising a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, an inverter, and the terminal of claim 8;
the target energy storage module is connected with a power grid bus through the energy storage converter, and the flywheel energy storage module is connected with the power grid bus through the rectifier and the inverter in sequence.
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