Frequency modulation control method for improving frequency intensity of grid-forming type energy storage converter

Abstract

The invention discloses a frequency modulation control method of a network-building type energy storage converter for improving frequency intensity, and the method comprises the steps: building a frequency deviation maximum value expression based on a frequency response model of the network-building type energy storage converter; when the frequency modulation of the network construction type energy storage converter is not considered, calculating a power grid system frequency intensity coefficient according to a given power grid system frequency deviation maximum value and a frequency deviation maximum value expression; when the frequency intensity coefficient of the power grid system is smaller than a preset threshold value, calculating a control parameter of the network-forming type energy storage converter; and performing frequency modulation control on the power grid system according to the control parameters and a pre-constructed adaptive inertia and damping parameter optimization control strategy.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage converter control, and more specifically, to a frequency modulation control method for a grid-type energy storage converter for improving frequency intensity. Background Art

[0002] In recent years, large-scale wind power, photovoltaic and other new energy sources have been decoupled from the system frequency through power electronic equipment, and are unable to provide synchronous inertia support to the system. At the same time, the impact of active power on the system is increasing. Faults such as large-capacity DC interlocking and chain disconnection of new energy clusters will deteriorate various frequency indicators, seriously threatening the safety and stability of system frequency under large disturbances, and the risk of triggering the third line of defense to cause machine / load shedding is gradually increasing. Energy storage is used in the active power support of high-proportion new energy systems due to its control flexibility and rapid response characteristics. The energy storage converter serves as the interface between the system and the device, and its control method and active output characteristics of energy storage play a key role.

[0003] Energy storage participating in frequency support and regulation is divided into grid-following type and grid-building type. Among them, grid-building energy storage has the characteristics of a voltage source, and its support characteristics are far superior to those of the grid-following type. It is currently a hot topic of research. The frequency support capability of grid-building energy storage depends on the functional energy reserve and control method on the source side. In order to avoid the problem of secondary frequency drop of the system caused by the recovery process after the power electronic power supply participates in the frequency regulation, the engineering practice is to try not to use power electronic power supply to participate in frequency regulation when the synchronous machine frequency regulation resources are sufficient. Therefore, it is of great practical significance to improve the frequency support strength of grid-building energy storage during transient periods. It is necessary to evaluate the system frequency response capability in real time, adopt grid-building energy storage frequency control when the frequency exceeds the limit, and adopt different control strategies at different frequency change stages to achieve the purpose of suppressing rapid frequency drop and accelerating frequency recovery speed. Therefore, how to improve the frequency support capability of energy storage converters has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a frequency modulation control method for a grid-type energy storage inverter with improved frequency intensity.

[0005] According to one aspect of the present invention, a frequency modulation control method for a grid-type energy storage converter for improving frequency strength is provided, comprising:

[0006] Based on the frequency response model of the grid-type energy storage converter, the maximum frequency deviation expression is constructed;

[0007] When the frequency modulation of the grid-type energy storage converter is not considered, the frequency intensity coefficient of the power grid system is calculated according to the maximum frequency deviation of the given power grid system and the maximum frequency deviation expression;

[0008] When the frequency intensity coefficient of the power grid system is less than a preset threshold, the control parameters of the grid-connected energy storage converter are calculated;

[0009] The power grid system is frequency-controlled according to the control parameters and the pre-built adaptive inertia and damping parameter optimization control strategy.

[0010] Optionally, based on the frequency response model of the energy storage converter, an expression for the maximum frequency deviation is constructed, including:

[0011] Derivative the frequency response expression of the frequency response model to obtain the expression of the maximum frequency deviation occurrence time;

[0012] Substitute the maximum frequency deviation occurrence time expression into the frequency response expression to obtain the maximum frequency deviation expression.

[0013] Optionally, the maximum frequency deviation Δf max The expression is:

[0014]

[0015] in,

[0016]

[0017] In the formula, R, T R 、F H They are the governor speed gain, reheater time constant, high pressure cylinder power ratio, △P sys is the system disturbance power, H sys is the equivalent inertia time constant, H sys =(K ns *H n +K ms *H m ) / (K ns +K ms ), D sys is the load frequency regulation characteristic, K ms is the proportion of conventional installed capacity, K ns is the proportion of installed capacity of new energy generators, K W is the grid-type droop control coefficient, K VD is the transient damping control coefficient, K n is the proportion of renewable energy units participating in frequency regulation, H m is the inertia of the synchronous machine, H n is the virtual inertia of new energy, t m is the maximum frequency deviation occurrence time, α is the frequency gain, ξ is the damping ratio, ω n is the rated angular frequency.

[0018] Optionally, when the frequency modulation of the grid-type energy storage converter is not considered, the frequency intensity coefficient of the power grid system is calculated according to the given maximum frequency deviation of the system and the maximum frequency deviation expression, including:

[0019] When the frequency modulation of the grid-type energy storage converter is not considered, the maximum frequency deviation of the given system is substituted into the maximum frequency deviation expression to obtain the maximum disturbance power that the system can withstand.

[0020] The frequency intensity coefficient of the power grid system is calculated based on the maximum disturbance power and the system disturbance power.

[0021] Optionally, the control parameters include internal potential and virtual internal potential phase angle,

[0022] Calculate the control parameters of the grid-connected energy storage converter, including:

[0023] A constant voltage control method is used to generate a frequency-modulated controlled internal potential;

[0024] Simulate the governor characteristics of the synchronous generator set prime mover to obtain the power reference value addition;

[0025] The synchronous generator rotor motion equation is simulated, and according to the power reference value addition, inertia and damping links are introduced into the control to enhance the flexible grid-connected characteristics of the converter and obtain the virtual internal potential phase angle for frequency control.

[0026] Optionally, the calculation formula of the internal potential E is:

[0027]

[0028] In the formula, k vp is the proportionality factor of the voltage controller, k vi is the integral coefficient of the voltage controller, U t * is the reference value of the AC voltage amplitude at the grid connection point, U t is the AC voltage amplitude at the grid connection point.

[0029] Optionally, the power reference value additional amount ΔP freq The calculation formula is:

[0030] ΔP freq =K W (f * -f)|f * -f|≥f deadzone

[0031] In the formula, f * Set the reference value for frequency, f deadzone is the speed regulator control dead zone, f is the measured frequency value, K W is the grid-type sag control coefficient.

[0032] Optionally, the synchronous generator rotor motion equation is simulated, and according to the power reference value addition, inertia and damping links are introduced into the control to enhance the flexible grid-connected characteristics of the converter and obtain the virtual internal potential phase angle of frequency control, including:

[0033] The sum of the power reference value addition and the active reference instruction is used as the virtual mechanical power of the grid-type energy storage converter, and the actual output active power of the converter is used as the virtual electromagnetic power;

[0034] The virtual speed of the grid-type energy storage converter is obtained by passing the difference between the virtual mechanical power and the virtual electromagnetic power through the virtual inertia and damping control links;

[0035] The virtual rotation speed is integrated to obtain the virtual internal potential phase angle.

[0036] Optionally, the virtual inertia and damping control link is controlled by a transient damping control coefficient and a grid-type droop control coefficient, where:

[0037] The expression of transient damping control coefficient is:

[0038]

[0039] Where, T w , T3, T4 are the time constants of the damping regulator, K D is the transient damping control proportional coefficient; s is the Laplace operator, D p is the damping coefficient of the virtual synchronous machine.

[0040] The grid-type droop control coefficient is obtained by solving the maximum frequency deviation expression. The calculation formula of the grid-type droop control coefficient is:

[0041]

[0042] Where Δf max is the maximum frequency deviation, α is the frequency gain, ξ is the damping ratio, ω n is the rated angular frequency, △P sys is the system disturbance power, D sys is the load frequency regulation characteristic, R is the speed regulator gain after the conventional unit is equal, K n is the proportion of renewable energy units participating in frequency regulation, Δf max is the maximum frequency deviation, t m is the time when the maximum frequency deviation occurs.

[0043] According to another aspect of the present invention, a frequency modulation control device for a grid-type energy storage converter for improving frequency intensity is provided, comprising:

[0044] A construction module, used to construct a maximum frequency deviation expression based on a frequency response model of a grid-type energy storage converter;

[0045] The first calculation module is used to calculate the frequency intensity coefficient of the power grid system according to the maximum frequency deviation of the given power grid system and the maximum frequency deviation expression when the frequency modulation of the grid-type energy storage converter is not considered;

[0046] The second calculation module is used to calculate the control parameters of the grid-type energy storage converter when the frequency intensity coefficient of the power grid system is less than a preset threshold;

[0047] The control module is used to perform frequency control on the power grid system according to the control parameters and the pre-built adaptive inertia and damping parameter optimization control strategy.

[0048] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and the computer program is used to execute the method described in any one of the above aspects of the present invention.

[0049] According to another aspect of the present invention, an electronic device is provided, comprising: a processor; a memory for storing instructions executable by the processor; the processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of the above aspects of the present invention.

[0050] Therefore, the present invention provides a frequency modulation control method for a grid-type energy storage converter that improves frequency strength. Based on the frequency response model of the grid-type energy storage converter, an expression for the maximum frequency deviation is constructed; when the frequency modulation of the grid-type energy storage converter is not considered, the frequency strength coefficient of the grid system is calculated according to the maximum frequency deviation of the given grid system and the expression for the maximum frequency deviation; when the frequency strength coefficient of the grid system is less than a preset threshold, the control parameters of the grid-type energy storage converter are calculated; the grid system is frequency-modulated and controlled according to the control parameters and the pre-constructed adaptive inertia and damping parameter optimization control strategy. It can participate in frequency modulation and inertia support during transient periods, and can improve the frequency stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0052] Figure 1 It is a flow chart of a frequency modulation control method of a grid-type energy storage converter for improving frequency intensity provided by an exemplary embodiment of the present invention;

[0053] Figure 2 is a schematic diagram of frequency control and system structure provided by an exemplary embodiment of the present invention;

[0054] Figure 3 It is a simulation diagram comparing the frequency support strength of a grid-type energy storage provided by an exemplary embodiment of the present invention;

[0055] Figure 4 It is a structural schematic diagram of a frequency modulation control device of a grid-type energy storage converter for improving frequency intensity provided by an exemplary embodiment of the present invention;

[0056] Figure 5 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0057] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described here.

[0058] It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0059] Those skilled in the art can understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, etc., and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0060] It should also be understood that, in the embodiments of the present invention, “plurality” may refer to two or more than two, and “at least one” may refer to one, two or more than two.

[0061] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0062] In addition, the term "and / or" in the present invention is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects before and after are in an "or" relationship.

[0063] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced to each other, and for the sake of brevity, they will not be described one by one.

[0064] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0065] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0066] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0067] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0068] Embodiments of the present invention can be applied to electronic devices such as terminal devices, computer systems, servers, etc., which can operate with many other general or special computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, servers, etc. include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, small computer systems, large computer systems, and distributed cloud computing technology environments including any of the above systems, etc.

[0069] Electronic devices such as terminal devices, computer systems, servers, etc. can be described in the general context of computer system executable instructions (such as program modules) executed by computer systems. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in a distributed cloud computing environment, where tasks are performed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media including storage devices.

[0070] Exemplary Methods

[0071] Figure 1 FIG. 1 is a flow chart of a frequency modulation control method of a grid-type energy storage converter for improving frequency intensity provided by an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as Figure 1 As shown, the frequency modulation control method 100 of the grid-type energy storage converter for improving the frequency strength includes the following steps:

[0072] Step 101, constructing a maximum frequency deviation expression based on a frequency response model of a grid-connected energy storage converter;

[0073] Step 102, when the frequency modulation of the grid-type energy storage converter is not considered, the frequency intensity coefficient of the grid system is calculated according to the maximum frequency deviation of the given grid system and the maximum frequency deviation expression;

[0074] Step 103, when the frequency intensity coefficient of the power grid system is less than a preset threshold, calculating the control parameters of the grid-connected energy storage converter;

[0075] Step 104 , frequency modulation control is performed on the power grid system according to the control parameters and the pre-built adaptive inertia and damping parameter optimization control strategy.

[0076] Specifically, the present invention proposes a grid-type energy storage converter control device for improving frequency strength, which can effectively improve the frequency support capability of the system during transient periods, thereby improving the frequency strength of the system. The specific implementation process of the method is as follows:

[0077] Step 1: Derive the maximum frequency deviation expression based on the frequency response model:

[0078] Considering the frequency modulation of new energy and the role of inertia support, assuming that the disturbance is a step function, the frequency response expression is obtained:

[0079]

[0080] Where: R.T R 、F H They are the governor speed gain, reheater time constant, high pressure cylinder power ratio, △P sys is the system disturbance power, H sys is the equivalent inertia time constant, and H sys =(K ns *H n +K ms *H m ) / (K ns +K ms ), D sys is the load frequency regulation characteristic, K ms is the proportion of conventional installed capacity, K ns is the proportion of installed capacity of new energy generators, K W is the grid-type droop control coefficient, K VD is the transient damping control coefficient, K n is the proportion of renewable energy units participating in frequency regulation, H m is the inertia of the synchronous machine, H n It is the virtual inertia of new energy;

[0081] Derivative equation (1) and set its derivative value to 0 to obtain the maximum frequency deviation occurrence time:

[0082]

[0083] Substituting equation (2) into the time domain expression (1), we can obtain the maximum frequency deviation:

[0084]

[0085] Step 2: When grid-type frequency regulation is not considered, calculate the frequency intensity coefficient of the power grid system (defined by the tolerable disturbance power)

[0086] Given the maximum value of the system frequency deviation that the system can withstand, the inverse solution is used to obtain the maximum disturbance power that the system can withstand, which is used as the maximum strength when the system needs the grid-type to provide frequency support. When the grid-type energy storage converter does not participate in primary frequency modulation and inertia control, the maximum disturbance power that the system can withstand is:

[0087]

[0088] Define the frequency intensity coefficient of the power grid system:

[0089]

[0090] When the disturbance △P sys >△P max , that is, the intensity coefficient η is less than 1, then the grid-type energy storage converter needs to be started for frequency support, otherwise the frequency is considered stable.

[0091] Step 3: Design of network control parameters

[0092] A network control strategy including virtual frequency modulation control, virtual inertia control and damping control is proposed. Figure 2 shown.

[0093] The internal potential E is generated by constant voltage control, and its expression is:

[0094]

[0095] In the formula, k vp is the proportional coefficient of the voltage controller, k vi is the integral coefficient of the voltage controller, U t * is the reference value of the AC voltage amplitude at the grid connection point, U t is the AC voltage amplitude at the grid connection point.

[0096] The speed governor characteristics of the synchronous generator prime mover are simulated and its Pf characteristics are simplified. The converter detects the actual frequency of the power grid and compares it with the reference frequency. After passing through the dead zone control module, if the frequency deviation exceeds the set dead zone width, the actual deviation is output; otherwise, the output is 0. The output frequency deviation is multiplied by the droop coefficient to obtain the power reference value addition △P freq .

[0097] ΔP freq =K W (f * -f) |f * -f|≥f deadzone (6)

[0098] In the formula, f * Set the reference value for frequency, f deadzone is the speed regulator control dead zone, and f is the measured frequency value.

[0099] The synchronous generator rotor motion equation is simulated, and inertia and damping links are introduced in the control to enhance the flexible grid-connected characteristics of the converter. The sum of the additional reference power obtained in the virtual frequency modulation control link and the active reference command is used as the virtual mechanical power of the converter, and the actual output active power of the converter is used as the virtual electromagnetic power. The difference between the two is passed through the inertia and damping control link to obtain the virtual speed of the energy storage converter, and the virtual internal potential phase angle can be obtained by integration.

[0100] To enhance the virtual damping control capability, the transient damping control coefficient consists of two parts in parallel.

[0101]

[0102] Where, T w , T3, T4 are the time constants of the damping regulator, K D is the transient damping control proportional coefficient.

[0103] According to the formula The solution is that the grid-type droop coefficient required is:

[0104]

[0105] Step 4: Adaptive inertia and damping parameter optimization control

[0106] When the frequency reaches the lowest point, in order to reduce the maximum frequency deviation, the inertia should be increased as much as possible and the damping coefficient should be kept unchanged; after reaching the maximum deviation, in the process of recovering to the steady-state frequency, the damping coefficient should be increased as much as possible and the inertia should be kept unchanged. Therefore, an adaptive inertia and droop parameter optimization control is proposed.

[0107] The inertia and damping parameters are optimized and controlled at different stages:

[0108]

[0109] Where, J is the system equivalent inertia time constant, K L is the system equivalent damping coefficient, k d is the damping proportional coefficient, k j is the inertia proportional coefficient.

[0110] To prevent oscillation or steady-state deviation from causing frequent adaptive parameter control actions, set J and K L The frequency change rate of the parameters start dead zone are: M j and M d .

[0111] The present invention proposes a grid-type energy storage converter control device for improving frequency strength, which can participate in frequency modulation and inertia support during transient periods and improve the frequency stability of the system. Figure 2 The system structure of the simulation experiment was carried out. When t=1s, a power shortage disturbance occurred. The grid-type control did not participate in the frequency modulation, the 20% grid-type control and the 60% grid-type control participated in the frequency modulation. Figure 3 It can be seen that the grid-type participating in frequency modulation can effectively reduce the maximum frequency deviation and the steady-state frequency deviation. Therefore, in the transient process, the frequency stability strength of the system is increased. The simulation results verify the effectiveness of the grid-type energy storage converter control device that improves the frequency strength.

[0112] Therefore, the present invention provides a frequency modulation control method for a grid-type energy storage converter for improving frequency strength. Based on the frequency response model of the grid-type energy storage converter, an expression for the maximum frequency deviation is constructed; when the frequency modulation of the grid-type energy storage converter is not considered, the frequency strength coefficient of the grid system is calculated according to the maximum frequency deviation of the given grid system and the expression for the maximum frequency deviation; when the frequency strength coefficient of the grid system is less than a preset threshold, the control parameters of the grid-type energy storage converter are calculated; and the grid system is frequency-modulated and controlled according to the control parameters and the pre-constructed adaptive inertia and damping parameter optimization control strategy. It can participate in frequency modulation and inertia support during transient periods, and can improve the frequency stability of the system.

[0113] Exemplary Devices

[0114] Figure 4 FIG. 1 is a schematic diagram of a frequency modulation control device for a grid-type energy storage converter for improving frequency intensity provided by an exemplary embodiment of the present invention. Figure 4 As shown, the device 400 includes:

[0115] A construction module 410 is used to construct a maximum frequency deviation expression based on a frequency response model of a grid-type energy storage converter;

[0116] The first calculation module 420 is used to calculate the frequency intensity coefficient of the power grid system according to the maximum frequency deviation of the given power grid system and the maximum frequency deviation expression when the frequency modulation of the grid-type energy storage converter is not considered;

[0117] The second calculation module 430 is used to calculate the control parameters of the grid-type energy storage converter when the frequency intensity coefficient of the power grid system is less than a preset threshold value;

[0118] The control module 440 is used to perform frequency control on the power grid system according to the control parameters and the pre-built adaptive inertia and damping parameter optimization control strategy.

[0119] Optionally, the construction module 410 includes:

[0120] The first acquisition submodule is used to derive the frequency response expression of the frequency response model to obtain the maximum frequency deviation occurrence time expression;

[0121] The second acquisition submodule is used to bring the maximum frequency deviation occurrence time expression into the frequency response expression to obtain the maximum frequency deviation expression.

[0122] Optionally, the maximum frequency deviation Δf max The expression is:

[0123]

[0124] in,

[0125]

[0126] In the formula, R, T R 、F H They are the governor speed gain, reheater time constant, high pressure cylinder power ratio, △P sys is the system disturbance power, H sys is the equivalent inertia time constant, H sys =(K ns *H n +K ms *H m ) / (K ns +K ms ), D sys is the load frequency regulation characteristic, K ms is the proportion of conventional installed capacity, K ns is the proportion of installed capacity of new energy generators, K W is the grid-type droop control coefficient, K VD is the transient damping control coefficient, K n is the proportion of renewable energy units participating in frequency regulation, Hm is the inertia of the synchronous machine, H n is the virtual inertia of new energy, t m is the maximum frequency deviation occurrence time, α is the frequency gain, ξ is the damping ratio, ω n is the rated angular frequency.

[0127] Optionally, the first calculation module 420 includes:

[0128] A solving submodule is used to bring the maximum value of the given system frequency deviation into the maximum value expression of the frequency deviation to solve and obtain the maximum disturbance power that the system can withstand when the frequency modulation of the grid-type energy storage converter is not considered;

[0129] The calculation submodule is used to calculate the frequency intensity coefficient of the power grid system according to the maximum disturbance power and the system disturbance power.

[0130] Optionally, the control parameters include internal potential and virtual internal potential phase angle,

[0131] The second calculation module 430 includes:

[0132] A generating submodule, for generating an internal potential for frequency modulation control by adopting a constant voltage control method;

[0133] The third acquisition submodule is used to simulate the governor characteristics of the prime mover of the synchronous generator set and obtain the power reference value addition;

[0134] The fourth acquisition submodule is used to simulate the synchronous generator rotor motion equation, introduce inertia and damping links in the control according to the power reference value addition, enhance the flexible grid-connected characteristics of the converter, and obtain the virtual internal potential phase angle of frequency control.

[0135] Optionally, the calculation formula of the internal potential E is:

[0136]

[0137] In the formula, k vp is the proportionality factor of the voltage controller, k vi is the integral coefficient of the voltage controller, U t * is the reference value of the AC voltage amplitude at the grid connection point, U t is the AC voltage amplitude at the grid connection point.

[0138] Optionally, the power reference value additional amount ΔP freq The calculation formula is:

[0139] ΔP freq =K W (f * -f)|f * -f|≥fdeadzone

[0140] In the formula, f * Set the reference value for frequency, f deadzone is the speed regulator control dead zone, f is the measured frequency value, K W is the grid-type sag control coefficient.

[0141] Optionally, the fourth acquisition submodule includes:

[0142] As a unit, it is used to take the sum of the power reference value addition and the active reference instruction as the virtual mechanical power of the grid-type energy storage converter, and take the actual output active power of the converter as the virtual electromagnetic power;

[0143] An obtaining unit is used to obtain a virtual speed of the grid-type energy storage converter by passing the difference between the virtual mechanical power and the virtual electromagnetic power through a virtual inertia and damping control link;

[0144] The integration unit is used to integrate the virtual rotation speed to obtain the virtual internal potential phase angle.

[0145] Optionally, the virtual inertia and damping control link is controlled by a transient damping control coefficient and a grid-type droop control coefficient, where:

[0146] The expression of transient damping control coefficient is:

[0147]

[0148] Where, T w , T3, T4 are the time constants of the damping regulator, K D is the transient damping control proportional coefficient; s is the Laplace operator, D p is the damping coefficient of the virtual synchronous machine.

[0149] The grid-type droop control coefficient is obtained by solving the maximum frequency deviation expression. The calculation formula of the grid-type droop control coefficient is:

[0150]

[0151] Where Δf max is the maximum frequency deviation, α is the frequency gain, ξ is the damping ratio, ω n is the rated angular frequency, △P sys is the system disturbance power, D sys is the load frequency regulation characteristic, R is the speed regulator gain after the conventional unit is equal, K n is the proportion of renewable energy units participating in frequency regulation, Δf max is the maximum frequency deviation, t m is the time when the maximum frequency deviation occurs.

[0152] Exemplary Electronic Devices

[0153] Figure 5 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. Figure 5 As shown, the electronic device 50 includes one or more processors 51 and a memory 52 .

[0154] The processor 51 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0155] The memory 52 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 51 may run the program instructions to implement the methods of the software programs of the various embodiments of the present invention described above and / or other desired functions. In one example, the electronic device may also include: an input device 53 and an output device 54, which are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0156] In addition, the input device 53 may also include, for example, a keyboard, a mouse, etc.

[0157] The output device 54 can output various information to the outside. The output device 54 can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0158] Of course, to simplify, Figure 5 Only some of the components related to the present invention in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, the electronic device may further include any other appropriate components according to specific application conditions.

[0159] Exemplary computer program products and computer-readable storage media

[0160] In addition to the above-mentioned methods and devices, an embodiment of the present invention may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above-mentioned "Exemplary Method" section of this specification.

[0161] The computer program product may be written in any combination of one or more programming languages ​​to write program code for performing the operations of the embodiments of the present invention, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0162] In addition, an embodiment of the present invention may also be a computer-readable storage medium having computer program instructions stored thereon, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above “Exemplary Method” section of this specification.

[0163] The computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can include, for example, but is not limited to, a system, system or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0164] The basic principle of the present invention is described above in conjunction with specific embodiments. However, it should be pointed out that the advantages, strengths, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. must be possessed by each embodiment of the present invention. In addition, the specific details disclosed above are only for the purpose of illustration and facilitation of understanding, rather than limitation, and the above details do not limit the present invention to being implemented by adopting the above specific details.

[0165] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system embodiment, since it basically corresponds to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0166] The block diagrams of the devices, systems, equipment, and systems involved in the present invention are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, systems, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The word "such as" used here refers to the phrase "such as but not limited to", and can be used interchangeably with it.

[0167] The method and system of the present invention may be implemented in many ways. For example, the method and system of the present invention may be implemented by software, hardware, firmware or any combination of software, hardware, firmware. The above order of steps for the method is only for illustration, and the steps of the method of the present invention are not limited to the order specifically described above, unless otherwise specifically stated. In addition, in some embodiments, the present invention may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present invention. Thus, the present invention also covers a recording medium storing a program for executing the method according to the present invention.

[0168] It should also be noted that in the system, device and method of the present invention, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present invention. The above description of the disclosed aspects is provided to enable any technician in the field to make or use the present invention. Various modifications to these aspects are very obvious to those skilled in the art, and the general principles defined here can be applied to other aspects without departing from the scope of the present invention. Therefore, the present invention is not intended to be limited to the aspects shown here, but in accordance with the widest range consistent with the principles and novel features disclosed here.

[0169] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A frequency modulation control method for a grid-type energy storage converter for improving frequency intensity, characterized in that: include: Based on the frequency response model of the grid-type energy storage converter, the maximum frequency deviation expression is constructed; When the frequency modulation of the grid-type energy storage converter is not considered, the frequency intensity coefficient of the grid system is calculated according to the maximum frequency deviation value of the given grid system and the expression of the maximum frequency deviation value; When the frequency intensity coefficient of the power grid system is less than a preset threshold, calculating the control parameters of the grid-type energy storage converter; The power grid system is frequency-controlled according to the control parameters and a pre-built adaptive inertia and damping parameter optimization control strategy.

2. The method according to claim 1, characterized in that Based on the frequency response model of the energy storage converter, the maximum frequency deviation expression is constructed, including: Derivative the frequency response expression of the frequency response model to obtain the maximum frequency deviation occurrence time expression; Substitute the maximum frequency deviation occurrence time expression into the frequency response expression to obtain the maximum frequency deviation expression.

3. The method according to claim 2, characterized in that The maximum frequency deviation The expression is: in, In the formula, R, T R 、F H They are the governor speed gain, reheater time constant, high pressure cylinder power ratio, △P sys is the system disturbance power, H sys is the equivalent inertia time constant, H sys =(K ns *H n +K ms *H m ) / (K ns +K ms ), D sys is the load frequency regulation characteristic, K ms is the proportion of conventional installed capacity, K ns is the proportion of installed capacity of new energy generators, K W is the grid-type droop control coefficient, K VD is the transient damping control coefficient, K n is the proportion of renewable energy units participating in frequency regulation, H m is the inertia of the synchronous machine, H n is the virtual inertia of new energy, t m is the maximum frequency deviation occurrence time, α is the frequency gain, ξ is the damping ratio, ω n is the rated angular frequency.

4. The method according to claim 1, characterized in that: When the frequency modulation of the grid-type energy storage converter is not considered, the frequency intensity coefficient of the power grid system is calculated according to the given maximum value of the system frequency deviation and the expression of the maximum value of the frequency deviation, including: When the frequency modulation of the grid-type energy storage converter is not considered, the maximum value of the given system frequency deviation is brought into the maximum value expression of the frequency deviation to solve and obtain the maximum disturbance power that the system can withstand; The power grid system frequency intensity coefficient is calculated according to the maximum disturbance power and the system disturbance power.

5. The method according to claim 1, characterized in that The control parameters include internal potential and virtual internal potential phase angle, Calculating the control parameters of the grid-connected energy storage converter includes: A constant voltage control method is used to generate a frequency-modulated controlled internal potential; Simulate the governor characteristics of the synchronous generator set prime mover to obtain the power reference value addition; The synchronous generator rotor motion equation is simulated, and according to the power reference value addition, inertia and damping links are introduced into the control to enhance the flexible grid-connected characteristics of the converter and obtain the virtual internal potential phase angle of frequency control.

6. The method according to claim 5, characterized in that The calculation formula of the internal potential E is: In the formula, k vp is the proportionality factor of the voltage controller, k vi is the integral coefficient of the voltage controller, U t * is the reference value of the AC voltage amplitude at the grid connection point, U t is the AC voltage amplitude at the grid connection point.

7. The method according to claim 5, characterized in that The power reference value additional amount ΔP freq The calculation formula is: ΔP freq =K W (f * -f)|f * -f|≥f deadzone In the formula, f * Set the reference value for frequency, f deadzone is the speed regulator control dead zone, f is the measured frequency value, K W is the grid-type sag control coefficient.

8. The method according to claim 5, characterized in that Simulate the synchronous generator rotor motion equation, introduce inertia and damping links in the control according to the power reference value addition, enhance the flexible grid-connected characteristics of the converter, and obtain the virtual internal potential phase angle of frequency control, including: The sum of the power reference value addition and the active reference instruction is used as the virtual mechanical power of the grid-type energy storage converter, and the actual output active power of the converter is used as the virtual electromagnetic power; The virtual speed of the grid-type energy storage converter is obtained by passing the difference between the virtual mechanical power and the virtual electromagnetic power through the virtual inertia and damping control links; The virtual rotation speed is integrated to obtain the frequency-controlled virtual internal potential phase angle.

9. The method according to claim 8, characterized in that The virtual inertia and damping control link is controlled by the transient damping control coefficient and the grid-type droop control coefficient, where: The expression of the transient damping control coefficient is: Where, T w , T3, T4 are the time constants of the damping regulator, K D is the transient damping control proportional coefficient; s is the Laplace operator, D p is the damping coefficient of the virtual synchronous machine. The grid-type droop control coefficient is obtained by solving the maximum frequency deviation expression. The calculation formula of the grid-type droop control coefficient is: Where Δf max is the maximum frequency deviation, α is the frequency gain, ξ is the damping ratio, ω n is the rated angular frequency, △P sys is the system disturbance power, D sys is the load frequency regulation characteristic, R is the speed regulator gain after the conventional unit is equal, K n is the proportion of renewable energy units participating in frequency regulation, Δf max is the maximum frequency deviation, t m is the time when the maximum frequency deviation occurs.

10. The method according to claim 1, characterized in that The adaptive inertia and damping parameter optimization control strategy is: Where J is the system equivalent inertia time constant, K L is the system equivalent damping coefficient, k d is the damping proportional coefficient, k j is the inertia proportional coefficient, J1 is the inertia coefficient of the virtual synchronous machine; set J and K L The frequency change rate of the parameters starts the dead zone respectively: M j and M d , △f is the actual frequency change.

11. A frequency modulation control device for a grid-type energy storage converter for improving frequency intensity, characterized in that: include: A construction module, used to construct a maximum frequency deviation expression based on a frequency response model of a grid-type energy storage converter; The first calculation module is used to calculate the frequency intensity coefficient of the power grid system according to the maximum frequency deviation of the given power grid system and the maximum frequency deviation expression when the frequency modulation of the grid-type energy storage converter is not considered; A second calculation module is used to calculate the control parameters of the grid-type energy storage converter when the frequency intensity coefficient of the power grid system is less than a preset threshold; The control module is used to perform frequency modulation control on the power grid system according to the control parameters and the pre-built adaptive inertia and damping parameter optimization control strategy.

12. The device according to claim 11, characterized in that Building blocks, including: A first acquisition submodule is used to derive the frequency response expression of the frequency response model to obtain the maximum frequency deviation occurrence time expression; The second acquisition submodule is used to substitute the maximum frequency deviation occurrence time expression into the frequency response expression to obtain the maximum frequency deviation value expression.

13. The device according to claim 12, characterized in that The maximum frequency deviation Δf max The expression is: in, In the formula, R, T R 、F H They are the governor speed gain, reheater time constant, high pressure cylinder power ratio, △P sys is the system disturbance power, H sys is the equivalent inertia time constant, H sys =(K ns *H n +K ms *H m ) / (K ns +K ms ), D sys is the load frequency regulation characteristic, K ms is the proportion of conventional installed capacity, K ns is the proportion of installed capacity of new energy generators, K W is the grid-type droop control coefficient, K VD is the transient damping control coefficient, K n is the proportion of renewable energy units participating in frequency regulation, H m is the inertia of the synchronous machine, H n is the virtual inertia of new energy, t m is the maximum frequency deviation occurrence time, α is the frequency gain, ξ is the damping ratio, ω n is the rated angular frequency.

14. The device according to claim 11, characterized in that The first computing module includes: A solving submodule, for, when the frequency modulation of the grid-type energy storage converter is not considered, bringing the given system frequency deviation maximum value into the frequency deviation maximum value expression to solve and obtain the maximum disturbance power that the system can withstand; The calculation submodule is used to calculate the frequency intensity coefficient of the power grid system according to the maximum disturbance power and the system disturbance power.

15. The device according to claim 11, characterized in that The control parameters include internal potential and virtual internal potential phase angle, The second calculation module calculates the control parameters of the grid-type energy storage converter, including: A generating submodule, for generating an internal potential for frequency modulation control by adopting a constant voltage control method; The third acquisition submodule is used to simulate the governor characteristics of the prime mover of the synchronous generator set and obtain the power reference value addition; The fourth acquisition submodule is used to simulate the synchronous generator rotor motion equation, introduce inertia and damping links in the control according to the power reference value addition, enhance the flexible grid-connected characteristics of the converter, and obtain the virtual internal potential phase angle of frequency control.

16. The device according to claim 15, characterized in that The calculation formula of the internal potential E is: In the formula, k vp is the proportionality factor of the voltage controller, k vi is the integral coefficient of the voltage controller, U t * is the reference value of the AC voltage amplitude at the grid connection point, U t is the AC voltage amplitude at the grid connection point.

17. The device according to claim 15, characterized in that The power reference value additional amount ΔP freq The calculation formula is: ΔP freq =K W (f * -f)|f * -f|≥f deadzone In the formula, f * Set the reference value for frequency, f deadzone is the speed regulator control dead zone, f is the measured frequency value, K W is the grid-type sag control coefficient.

18. The device according to claim 15, characterized in that The fourth acquisition submodule includes: As a unit, it is used to use the sum of the power reference value addition and the active reference instruction as the virtual mechanical power of the grid-type energy storage converter, and the actual output active power of the converter as the virtual electromagnetic power; An obtaining unit, used for obtaining a virtual rotation speed of the grid-type energy storage converter by passing the difference between the virtual mechanical power and the virtual electromagnetic power through a virtual inertia and damping control link; The integration unit is used to integrate the virtual rotation speed to obtain the virtual internal potential phase angle controlled by the frequency.

19. The device according to claim 18, characterized in that The virtual inertia and damping control link is controlled by the transient damping control coefficient and the grid-type droop control coefficient, where: The expression of the transient damping control coefficient is: Where, T w , T3, T4 are the time constants of the damping regulator, K D is the transient damping control proportional coefficient; s is the Laplace operator, D p is the damping coefficient of the virtual synchronous machine. The grid-type droop control coefficient is obtained by solving the maximum frequency deviation expression. The calculation formula of the grid-type droop control coefficient is: Where Δf max is the maximum frequency deviation, α is the frequency gain, ξ is the damping ratio, ω n is the rated angular frequency, △P sys is the system disturbance power, D sys is the load frequency regulation characteristic, R is the speed regulator gain after the conventional unit is equal, K n is the proportion of renewable energy units participating in frequency regulation, Δf max is the maximum frequency deviation, t m is the time when the maximum frequency deviation occurs.

20. The device according to claim 11, characterized in that The adaptive inertia and damping parameter optimization control strategy is: Where J is the system equivalent inertia time constant, K L is the system equivalent damping coefficient, k d is the damping proportional coefficient, k j is the inertia proportional coefficient, J1 is the inertia coefficient of the virtual synchronous machine; set J and K L The frequency change rate of the parameters starts the dead zone respectively: M j and M d , △f is the actual frequency change.

21. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 10.

22. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is used to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 1-10.

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