A method and device for simulating the equivalent inertia of a power grid

Abstract

The present invention discloses a method and device for simulating the equivalent inertia of a power grid, belonging to the technical field of new energy grid connection. Aiming at the problem that existing power grid simulation devices cannot verify the interaction characteristics between new energy units and the power grid under different equivalent inertia levels, the present invention realizes the simulation of the equivalent inertia of the power grid by establishing a frequency response model that takes into account the frequency response characteristics of thermal power units, hydropower units and new energy power generation equipment. The method includes: determining the proportion coefficient of each power source and the frequency response power, and constructing a frequency response model; calculating the active and reactive power of new energy based on the measured voltage and current; deriving the per-unit value of the reference angular frequency by combining the frequency response model with the active power, and determining the reference voltage through the reactive power; generating a modulation command by using a double closed-loop control of voltage and current to drive the inverter link to simulate the dynamic characteristics of the power grid. The present invention can simulate power grid scenarios with different inertia levels and verify the adaptability of new energy units to grid-source interaction in a complex power grid environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy grid connection, and particularly relates to a method and device for simulating the equivalent inertia of a power grid. Background Art

[0002] With the development of new energy technology, the power system presents the "dual high" characteristics of high proportion of new energy power generation and high proportion of power electronic devices, and the system inertia level gradually decreases. The access of new energy units without sufficient experimental verification to the power system will pose a huge challenge to the safe and stable operation of the system. The power grid simulation device can provide repeatable power grid disturbances and fault scenarios for new energy units and is the core equipment for new energy units to carry out grid connection test verification.

[0003] Currently, the power grid simulation device mainly simulates typical scenarios such as voltage harmonics / interharmonics, frequency deviation, and voltage faults of the power grid. However, the power grid simulation device does not consider the frequency response dynamics when multiple types of power sources are connected to the power grid. When simulating frequency disturbances, the output frequency shows a "rigid" characteristic and cannot verify the interaction characteristics between new energy units and the power grid under different equivalent inertia levels of the power grid. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and device for simulating the equivalent inertia of a power grid to solve the problem in the prior art that the interaction characteristics between new energy units and the power grid under different equivalent inertia levels of the power grid cannot be verified.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] In the first aspect of the present invention, a method for simulating the equivalent inertia of a power grid is provided. The power grid includes thermal power units, hydroelectric power units, and new energy power generation equipment. The method for simulating the equivalent inertia of the power grid includes:

[0007] Respectively determine the proportion coefficients of the thermal power units, hydroelectric power units, and new energy power generation equipment in the power grid, and the frequency response powers of the thermal power units, hydroelectric power units, and new energy power generation equipment; based on each proportion coefficient and each frequency response power, determine the frequency response model of the new energy power generation equipment accessing the power grid;

[0008] Based on the three-phase voltage and three-phase current at the inverter side of the machine-side transformer corresponding to the new energy power generation equipment, determine the active power and reactive power output by the new energy power generation equipment;

[0009] Based on the active power output by the new energy power generation equipment and the frequency response model, determine the per-unit value of the reference angular frequency of the power grid simulation device; based on the reactive power output by the new energy power generation equipment, and the virtual equivalent reactive power output by the thermal power units and hydroelectric power units, determine the reference voltage of the power grid simulation device;

[0010] Input the per-unit value of the reference angular frequency and the reference voltage of the power grid simulation device into the voltage closed-loop and current closed-loop control links to obtain the modulation voltage command, and generate the switching signal of the inverter link of the power grid simulation device according to the modulation voltage command.

[0011] Further, in the step of determining the frequency response model of the new energy power generation equipment accessing the power grid based on each proportion coefficient and each frequency response power, the frequency response model is expressed as:

[0012]

[0013] Where, is the system equivalent inertia; s is the complex frequency; is the per-unit value of the reference angular frequency of the power grid simulation device; is the load disturbance amount in the system; is the frequency response power of the thermal power unit; is the frequency response power of the hydropower unit; is the active power output of the new energy power generation equipment; is the initial active power output of the new energy; is the system equivalent damping.

[0014] Further, based on the active power output of the new energy power generation equipment and the frequency response model, determining the per-unit value of the reference angular frequency of the power grid simulation device includes:

[0015]

[0016] Where, is the per-unit value of the reference angular frequency; is the load disturbance amount in the system; is the active power output of the new energy power generation equipment; is the initial active power output of the new energy; is the system equivalent inertia; s is the complex frequency; is the system equivalent damping; is the frequency response transfer function of the hydropower and thermal power units.

[0017] Further, based on the reactive power output of the new energy power generation equipment, and the virtual equivalent reactive power output of the thermal power unit and the hydropower unit, determining the reference voltage of the power grid simulation device includes:

[0018]

[0019] In the formula, is the reference voltage of the power grid simulation device, is the voltage setting value, is the droop coefficient, is the reactive power setpoint, is the virtual equivalent reactive power output by thermal power and hydroelectric generating units, is the reactive power output by new energy power generation.

[0020] Furthermore, the per-unit value of the reference angular frequency and the reference voltage of the power grid simulation device are input into the voltage closed-loop and current closed-loop control links to obtain the modulation voltage command, including:

[0021] Generate the reference three-phase voltage of the power grid simulation device based on the per-unit value of the reference angular frequency of the power grid simulation device and the reference voltage of the power grid simulation device;

[0022] Perform Park transformation on the reference three-phase voltage of the power grid simulation device to generate the d-axis reference voltage and the q-axis reference voltage;

[0023] Generate the d-axis reference current and the q-axis reference current based on the voltage closed-loop control of the d-axis reference voltage and the q-axis reference voltage, and generate the modulation voltage command based on the current closed-loop control of the d-axis reference current and the q-axis reference current.

[0024] Furthermore, performing Park transformation on the reference three-phase voltage of the power grid simulation device to generate the d-axis reference voltage and the q-axis reference voltage includes:

[0025]

[0026] Wherein, 、 、 are respectively the reference three-phase voltage of the power grid simulation device; is the reference voltage of the power grid simulation device; is the rated angular frequency of the power grid; is the per-unit value of the reference angular frequency of the power grid simulation device; t represents time.

[0027] Furthermore, generating the d-axis reference current and the q-axis reference current based on the voltage closed-loop control of the d-axis reference voltage and the q-axis reference voltage, and generating the modulation voltage command based on the current closed-loop control of the d-axis reference current and the q-axis reference current includes:

[0028]

[0029] In the formula, 、 are respectively the modulation voltage commands of the d-axis and the q-axis; are respectively the transfer functions of the current loop and the voltage loop controllers of the power grid simulation device; 、 are respectively the d-axis component and the q-axis component of the voltage on the inverter side of the machine-side transformer; 、 They are respectively the d-axis and q-axis components of the output current of the machine-side transformer on the inverter side; , They are respectively the d-axis reference voltage and the q-axis reference voltage; It is the coupling compensation component.

[0030] In the second aspect of the present invention, a power grid equivalent inertia simulation device is provided. The power grid includes thermal power units, hydropower units, and new energy power generation equipment; the power grid equivalent inertia simulation device includes:

[0031] A model construction module, which is used to respectively determine the proportion coefficients of thermal power units, hydropower units, and new energy power generation equipment in the power grid, as well as the frequency response powers of thermal power units, hydropower units, and new energy power generation equipment; based on each proportion coefficient and each frequency response power, determine the frequency response model of new energy power generation equipment accessing the power grid;

[0032] A first calculation module, which is used to determine the active power and reactive power output by the new energy power generation equipment based on the three-phase voltage and three-phase current of the machine-side transformer corresponding to the new energy power generation equipment on the inverter side;

[0033] A second calculation module, which is used to determine the per-unit value of the reference angular frequency of the power grid simulation device based on the active power output by the new energy power generation equipment and the frequency response model; based on the reactive power output by the new energy power generation equipment, as well as the virtual equivalent reactive power output by thermal power units and hydropower units, determine the reference voltage of the power grid simulation device;

[0034] A third calculation module, which is used to input the per-unit value of the reference angular frequency of the power grid simulation device and the reference voltage of the power grid simulation device into the voltage closed-loop and current closed-loop control links to obtain a modulation voltage command, and generate a switching signal for the inverter link of the power grid simulation device according to the modulation voltage command.

[0035] In the third aspect of the present invention, an electronic device is provided, which includes a processor and a memory. The processor is used to execute a computer program stored in the memory to implement the power grid equivalent inertia simulation method as described above.

[0036] In the fourth aspect of the present invention, a computer-readable storage medium is provided. The computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by a processor, the power grid equivalent inertia simulation method as described above is implemented.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] In response to the grid connection test requirements of new energy power generation equipment, this solution proposes a method for simulating the equivalent inertia of the power grid. This method takes into account the frequency response constraints and can provide conditions for verifying the interaction characteristics between new energy and the power grid. This solution gives the calculation equations for the reference frequency and reference voltage of the control link of the power grid simulation device, and establishes a control strategy for the power grid simulation device to simulate the equivalent inertia of the power grid, providing a new functional technical solution for the power grid simulation device. By introducing a frequency response model, this method depicts the operation scenarios of power grids with different power source ratios, can provide richer test conditions for the new energy power generation equipment under test, verify the operation adaptability of new energy access to power grids with different inertia levels, can meet the test requirements of new energy distributed and centralized transmission systems, and provide technical and equipment support for the development of new energy technologies. A power grid equivalent inertia simulation device, an electronic device, and a computer-readable storage medium provided by the present invention also solve the problems raised in the background art section. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0040] Figure 1 is a structural block diagram of a power grid simulation device in an embodiment of the present invention;

[0041] Figure 2 is a flowchart of a method for simulating the equivalent inertia of a power grid in an embodiment of the present invention;

[0042] Figure 3 is a schematic diagram of a frequency response model in an embodiment of the present invention;

[0043] Figure 4 is a control block diagram of a method for simulating the equivalent inertia of a power grid in an embodiment of the present invention;

[0044] Figure 5 is a structural block diagram of a power grid equivalent inertia simulation device in an embodiment of the present invention;

[0045] Figure 6 is a structural block diagram of an electronic device in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0047] The following detailed descriptions are all exemplary descriptions, aiming to provide further details of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0048] Embodiment 1

[0049] In the present solution, the power grid simulation device referred to is as Figure 1 shown. The system input side of the power grid simulation device is connected to the power grid through switch CB1 and the grid-side transformer. The grid-side transformer is connected to the grid-side filter cabinet, and the grid-side filter cabinet is connected to the rectification link of the power grid simulation device. The rectification link and the inversion link are connected through a DC bus. The rectification link realizes the control of grid-side reactive power and DC bus voltage; the inversion link is connected to the new energy power generation equipment under test through the inversion-side filter cabinet, the machine-side transformer, and switch CB2. Different inertia levels of power grid simulation are realized through the simulation control of the equivalent inertia on the inversion side, and then a test environment is provided for the new energy power generation equipment under test.

[0050] In the present solution, the power grid is composed of the aggregation of synchronous generators such as hydropower and thermal power, and the new energy power generation equipment under test is connected to the power grid.

[0051] As Figure 2 and Figure 4 shown, a power grid equivalent inertia simulation method proposed in the present solution includes the following specific steps:

[0052] S1. Determine the proportion coefficients of thermal power units, hydropower units, and new energy power generation equipment in the power grid respectively, as well as the frequency response powers of thermal power units, hydropower units, and new energy power generation equipment; based on each proportion coefficient and each frequency response power, determine the frequency response model of the new energy power generation equipment connected to the power grid.

[0053] In the present solution, the proportion coefficient of thermal power units in the power grid is d m , the proportion coefficient of hydropower units in the power grid is d h , the proportion coefficient of new energy power generation equipment in the power grid is d w , and the following conditions are satisfied among the proportion coefficients:

[0054] (1)

[0055] Under the system frequency disturbance, considering the primary frequency regulation effect of thermal power units, the frequency response power of thermal power units can be expressed as:

[0056] (2)

[0057] In the formula, is the frequency response power of the thermal power unit, k m is the mechanical power gain coefficient of the thermal power unit, F HP is the work ratio of the high-pressure cylinder of the prime mover of the thermal power unit, T RH is the reheating time constant of the prime mover of the thermal power unit, R m is the droop coefficient of the governor of the thermal power unit, s is the complex frequency, is the change in the system angular frequency.

[0058] Under the system frequency disturbance, considering the primary frequency regulation of the hydropower unit, the frequency response power of the hydropower unit can be expressed as:

[0059] (3)

[0060] In the formula, is the frequency response power of the hydropower unit, T h is the response time constant of the hydropower unit, R h is the droop coefficient of the governor of the hydropower unit.

[0061] The frequency response power of the new energy power generation equipment is introduced:

[0062] (4)

[0063] In the formula, is the frequency response power of the new energy power generation equipment, is the new energy frequency response transfer function.

[0064] When the thermal power unit, hydropower unit and new energy are connected to the power grid, the system equivalent inertia is approximated as follows:

[0065] (5)

[0066] In the formula, H 1, H 2 are the inertia time constants of the thermal power unit and hydropower unit respectively, S 1, S 2 are the apparent capacities of the thermal power unit and hydropower unit respectively.

[0067] The frequency response characteristics of the thermal power unit, hydropower unit and new energy can be described by the following relational expressions:

[0068] (6)

[0069] In the formula, is the system equivalent damping, , are respectively the initial value of the load and the load disturbance amount in the system, , , are respectively the initial active power outputs of thermal power units, hydropower units and new energy.

[0070] Let the initial value of the system load be balanced with the initial active power outputs of hydropower units, thermal power units and new energy, that is , formula (6) can be simplified as follows:

[0071] (7)

[0072] Transform formula (7) to obtain the frequency response model of the new energy power generation equipment connected to the power grid, as Figure 3 shown. The frequency response model is expressed in the following form:

[0073] (8)

[0074] Among them, is the system equivalent inertia; s is the complex frequency; is the per-unit value of the grid angular frequency (i.e., the per-unit value of the reference angular frequency of the grid simulation device), ; is the load disturbance amount in the system; is the frequency response power of the thermal power unit; is the frequency response power of the hydropower unit; is the active power output of the new energy power generation equipment; is the initial active power output of the new energy; is the system equivalent damping.

[0075] S2. Determine the active power and reactive power output by the new energy power generation equipment based on the three-phase voltage and three-phase current on the inverter side of the machine-side transformer corresponding to the new energy power generation equipment.

[0076] It should be noted that the inverter side of the machine-side transformer in this solution refers to the side where the machine-side transformer is connected to the inverter-side filter cabinet.

[0077] Specifically, based on the three-phase voltage and three-phase current on the inverter side of the machine-side transformer corresponding to the new energy power generation equipment, calculate the instantaneous active power output by the new energy and the instantaneous reactive power output by the new energy respectively; to reduce control interference, the active power output by the new energy power generation equipment is obtained by filtering the instantaneous active power output by the new energy; the reactive power Obtained from the instantaneous output reactive power of new energy through filtering;

[0078] That is:

[0079] (9)

[0080] In the formula, is the harmonic angular frequency of the filter, is the quality factor.

[0081] (10)

[0082] S3. Based on the active power output by the new energy power generation equipment and the frequency response model, determine the per-unit value of the reference angular frequency of the power grid simulation device; based on the reactive power output by the new energy power generation equipment and the virtual equivalent reactive power output by the thermal power unit and the hydropower unit, determine the reference voltage of the power grid simulation device.

[0083] In this solution, based on the active power output by the new energy power generation equipment and the frequency response model, determining the per-unit value of the reference angular frequency of the power grid simulation device includes:

[0084] (11)

[0085] Among them, is the per-unit value of the reference angular frequency of the power grid simulation device; is the load disturbance amount in the system; is the active power output by the new energy power generation equipment; is the initial active power output of new energy; is the equivalent inertia of the system; s is the complex frequency; is the equivalent damping of the system; is the frequency response transfer function of the hydropower unit and the thermal power unit.

[0086] (12)

[0087] In this solution, considering the influence of the reactive power output of the synchronous power supply and new energy, based on the reactive power output by the new energy power generation equipment and the virtual equivalent reactive power output by the thermal power unit and the hydropower unit, determine the reference voltage of the power grid simulation device as follows:

[0088] (13)

[0089] In the formula, is the reference voltage of the power grid simulation device, is the voltage setting value, is the droop coefficient, is the reactive power setpoint, is the virtual equivalent reactive power output by the thermal power unit and the hydroelectric power unit, is the reactive power output by the new energy power generation.

[0090] S4. Input the per-unit value of the reference angular frequency of the power grid simulation device and the reference voltage of the power grid simulation device into the voltage-current double closed-loop control link to obtain the modulation voltage command, and generate the switching signal of the inverter link of the power grid simulation device according to the modulation voltage command.

[0091] In this solution, inputting the per-unit value of the reference angular frequency of the power grid simulation device and the reference voltage of the power grid simulation device into the voltage-current double closed-loop control link to obtain the modulation voltage command includes:

[0092] S41. Generate the reference three-phase voltage and reference three-phase current of the power grid simulation device based on the per-unit value of the reference angular frequency of the power grid simulation device and the reference voltage of the power grid simulation device.

[0093] Specifically, the reference three-phase voltage of the power grid simulation device is as follows:

[0094] (14)

[0095] Wherein, , , are the reference three-phase voltages of the power grid simulation device respectively; is the reference voltage of the power grid simulation device; is the rated angular frequency of the power grid; is the per-unit value of the reference angular frequency of the power grid simulation device; t represents time.

[0096] S42. Perform Park transformation on the reference three-phase voltage of the power grid simulation device to generate the d-axis reference voltage and q-axis reference voltage, generate the d-axis reference current and q-axis reference current based on the voltage closed-loop control of the d-axis reference voltage and q-axis reference voltage; generate the modulation voltage command based on the current closed-loop control of the d-axis reference current and q-axis reference current.

[0097] Specifically, in step S42, generating the d-axis reference current and q-axis reference current based on the voltage closed-loop control of the d-axis reference voltage and q-axis reference voltage, and generating the modulation voltage command based on the current closed-loop control of the d-axis reference current and q-axis reference current are shown in the following formula:

[0098] (15)

[0099] In the formula, , are the modulation voltage commands of the d-axis and q-axis respectively; is the transfer function of the current loop controller of the power grid simulation device, is the transfer function of the voltage loop controller of the power grid simulation device; and are the d-axis component and q-axis component of the voltage on the inverter side of the machine-side transformer respectively; and are the d-axis component and q-axis component of the current on the inverter side of the machine-side transformer respectively; The three-phase voltage collected from the inverter side of the machine-side transformer is transformed to obtain and , and the three-phase current collected from the inverter side of the machine-side transformer is transformed to obtain and ; and are the d-axis reference voltage and q-axis reference voltage respectively; is the coupling compensation component.

[0100] Finally, the modulation voltage commands and generate switching signals through the signal modulation link to control the inverter link of the power grid simulation device, and then realize the power grid equivalent inertia simulation control.

[0101] The power grid equivalent inertia simulation method provided by the above solution gives the operation scenarios of multiple types of power sources simulated by the power grid simulation device, introduces the frequency response model, and can realize the simulation of different new energy penetration rates and equivalent inertias by adjusting the frequency response related parameters and their ratios of thermal power and hydroelectric units in the model. Based on the frequency response model, the calculation methods of the reference frequency and reference voltage of the power grid simulation device are given, and through the double closed-loop control of voltage and current, the power grid simulation device realizes the simulation of power grids with different inertia levels, providing conditions for the test verification of new energy power generation equipment.

[0102] Through the setting of the ratio coefficient, this solution gives the operation scenarios of multiple types of power sources simulated by the power grid simulation device, introduces the frequency response model in the control link, and can test the frequency dynamic interaction characteristics of the measured new energy power generation equipment connected to different power grid conditions by adjusting the frequency response related parameters and their ratios of thermal power units and hydroelectric units in the model;

[0103] This solution takes into account the frequency response processes of thermal power units, hydroelectric units and the measured new energy power generation equipment, deduces the system frequency response model, and gives the calculation method of the reference frequency of the power grid simulation device; Considering the system voltage response characteristics under the reactive power output of synchronous units and the measured new energy power generation equipment, the calculation method of the reference voltage of the power grid simulation device is given.

[0104] Based on the above solution content, this solution realizes the simulation of power grids with different inertia levels and gives the equivalent inertia simulation control block diagram of the power grid simulation device.

[0105] Embodiment 2

[0106] As shown Figure 5 in the figure, based on the same inventive concept as the above embodiments, the present invention also provides a power grid equivalent inertia simulation device. The power grid includes thermal power units, hydroelectric power units, and new energy power generation equipment. The power grid equivalent inertia simulation device includes:

[0107] A model construction module, configured to respectively determine the proportion coefficients of the thermal power units, hydroelectric power units, and new energy power generation equipment in the power grid, and the frequency response powers of the thermal power units, hydroelectric power units, and new energy power generation equipment; based on the respective proportion coefficients and respective frequency response powers, determine the frequency response model for the new energy power generation equipment to access the power grid;

[0108] A first calculation module, configured to determine the active power and reactive power output by the new energy power generation equipment based on the three-phase voltage and three-phase current on the inverter side of the machine-side transformer corresponding to the new energy power generation equipment;

[0109] A second calculation module, configured to determine the per-unit value of the reference angular frequency of the power grid simulation device based on the active power output by the new energy power generation equipment and the frequency response model; determine the reference voltage of the power grid simulation device based on the reactive power output by the new energy power generation equipment and the virtual equivalent reactive powers output by the thermal power units and hydroelectric power units;

[0110] A third calculation module, configured to input the per-unit value of the reference angular frequency of the power grid simulation device and the reference voltage of the power grid simulation device into a voltage-current double closed-loop control link to obtain a modulation voltage command, and generate a switching signal for the inverter link of the power grid simulation device according to the modulation voltage command.

[0111] Embodiment 3

[0112] As shown Figure 6 in the figure, the present invention also provides an electronic device 100 for implementing the power grid equivalent inertia simulation method;

[0113] The electronic device 100 includes a memory 101, at least one processor 102, a computer program 103 stored in the memory 101 and executable on the at least one processor 102, and at least one communication bus 104.

[0114] The memory 101 can be used to store the computer program 103. The processor 102 realizes the steps of the power grid equivalent inertia simulation method in Embodiment 1 by running or executing the computer program stored in the memory 101 and calling the data stored in the memory 101.

[0115] The memory 101 may mainly include a program storage area and a data storage area. Among them, the program storage area may store an operating system, application programs required for at least one function (such as a sound playback function, an image playback function, etc.); the data storage area may store data created according to the use of the electronic device 100 (such as audio data, etc.). In addition, the memory 101 may include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage devices.

[0116] At least one processor 102 may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor 102 may be a microprocessor or the processor 102 may also be any conventional processor, etc. The processor 102 is the control center of the electronic device 100 and connects various parts of the entire electronic device 100 through various interfaces and lines.

[0117] The memory 101 in the electronic device 100 stores multiple instructions to implement a method for simulating the equivalent inertia of a power grid. The processor 102 can execute the multiple instructions to implement:

[0118] Respectively determine the proportion coefficients of thermal power units, hydropower units, and new energy power generation equipment in the power grid, and the frequency response power of thermal power units, hydropower units, and new energy power generation equipment; based on each proportion coefficient and each frequency response power, determine the frequency response model of the new energy power generation equipment connected to the power grid;

[0119] Based on the three-phase voltage and three-phase current on the inverter side of the machine-side transformer corresponding to the new energy power generation equipment, determine the active power and reactive power output by the new energy power generation equipment;

[0120] Based on the active power output by the new energy power generation equipment and the frequency response model, determine the per-unit value of the reference angular frequency of the power grid simulation device; based on the reactive power output by the new energy power generation equipment, and the virtual equivalent reactive power output by the thermal power units and hydropower units, determine the reference voltage of the power grid simulation device;

[0121] The per-unit value of the reference angular frequency and the reference voltage of the power grid simulation device are input into the voltage closed-loop and current closed-loop control links to obtain a modulation voltage command, and switching signals for the inverter link of the power grid simulation device are generated according to the modulation voltage command.

[0122] Embodiment 4

[0123] If the modules / units integrated in the electronic device 100 are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, to implement all or part of the processes in the above method embodiments of the present invention, it can also be completed by a computer program instructing relevant hardware. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium can include: any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, and read-only memory (ROM, Read-Only Memory).

[0124] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, system, or computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0125] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of processes and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0126] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in one or more of the flows Figure 1 one or more flows and / or blocks Figure 1 specified in a block or blocks.

[0127] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one or more of the flows Figure 1 one or more flows and / or blocks Figure 1 specified in a block or blocks.

[0128] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific embodiments of the present invention, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for simulating the equivalent inertia of a power grid, where the power grid includes thermal power units, hydroelectric power units, and new energy power generation equipment; characterized in that, The power grid equivalent inertia simulation method includes: Determining the proportion coefficients of thermal power units, hydropower units, and new energy power generation equipment in the power grid respectively, as well as the frequency response powers of thermal power units, hydropower units, and new energy power generation equipment under system frequency disturbances; Determining the frequency response model of new energy power generation equipment connected to the power grid based on each proportion coefficient and each frequency response power; Determining the active power and reactive power output by the new energy power generation equipment based on the three-phase voltage and three-phase current on the inverter side of the machine-side transformer corresponding to the new energy power generation equipment; Determining the per-unit value of the reference angular frequency of the power grid simulation device based on the active power output by the new energy power generation equipment and the frequency response model, including: Among them, is the per-unit value of the reference angular frequency of the power grid simulation device; is the load disturbance amount in the system; is the active power output of the new energy power generation equipment; is the initial active power output of the new energy; s is the complex frequency; is the equivalent damping of the system; is the frequency response transfer function of the hydropower and thermal power units; is the equivalent inertia of the system, expressed as: In the formula, H 1, H S 1, S d w is the proportion coefficient of new energy power generation equipment in the power grid; S S 2 are the apparent capacities of thermal power units and hydropower units respectively; 1, H S 2 are the inertia time constants of thermal power units and hydropower units respectively, Determining the reference voltage of the power grid simulation device based on the reactive power output by the new energy power generation equipment and the virtual equivalent reactive powers output by thermal power units and hydropower units, including: Wherein, is the reference voltage of the power grid simulation device, is the voltage set value, is the droop coefficient, is the reactive power set value, is the virtual equivalent reactive power output by thermal power and hydroelectric generating units, is the reactive power output by new energy power generation; Generating the reference three-phase voltage of the power grid simulation device based on the per-unit value of the reference angular frequency of the power grid simulation device and the reference voltage of the power grid simulation device; converting the reference three-phase voltage of the power grid simulation device through Park transformation to generate the d-axis reference voltage and q-axis reference voltage; generating the d-axis reference current and q-axis reference current based on the voltage closed-loop control of the d-axis reference voltage and q-axis reference voltage, generating the modulation voltage command based on the current closed-loop control of the d-axis reference current and q-axis reference current, and generating the switching signal of the inverter link of the power grid simulation device according to the modulation voltage command; The frequency response model is expressed as: Among them, is the frequency response power of the thermal power unit; is the frequency response power of the hydropower unit.

2. The grid equivalent inertia simulation method according to claim 1, characterized in that Converting the reference three-phase voltage of the power grid simulation device through Park transformation to generate the d-axis reference voltage and q-axis reference voltage, including: Among them, , , are the reference three-phase voltages of the power grid simulation device respectively; is the reference voltage of the power grid simulation device; is the rated angular frequency of the power grid; is the per-unit value of the reference angular frequency of the power grid simulation device; t represents time.

3. The grid equivalent inertia simulation method according to claim 1, characterized in that Generating the d-axis reference current and q-axis reference current based on the voltage closed-loop control of the d-axis reference voltage and q-axis reference voltage, generating the modulation voltage command based on the current closed-loop control of the d-axis reference current and q-axis reference current, including: Wherein, and are the modulation voltage commands for the d-axis and q-axis respectively; are the transfer functions of the current loop and voltage loop controllers of the power grid simulation device respectively; and are the d-axis component and q-axis component of the voltage of the machine-side transformer on the inverter side respectively; and are the dq-axis components of the current of the machine-side transformer on the inverter side respectively; and are the d-axis reference voltage and q-axis reference voltage respectively; is the coupling compensation component.

4. A power grid equivalent inertia simulation device for implementing the method of claim 1, wherein the power grid includes thermal power units, hydroelectric power units, and new energy power generation equipment; characterized in that, The power grid equivalent inertia simulation device includes: A model construction module for respectively determining the proportion coefficients of thermal power units, hydropower units, and new energy power generation equipment in the power grid, as well as the frequency response powers of thermal power units, hydropower units, and new energy power generation equipment; and determining the frequency response model of new energy power generation equipment connected to the power grid based on each proportion coefficient and each frequency response power; A first calculation module for determining the active power and reactive power output by the new energy power generation equipment based on the three-phase voltage and three-phase current on the inverter side of the machine-side transformer corresponding to the new energy power generation equipment; A second calculation module for determining the per-unit value of the reference angular frequency of the power grid simulation device based on the active power output by the new energy power generation equipment and the frequency response model; and determining the reference voltage of the power grid simulation device based on the reactive power output by the new energy power generation equipment and the virtual equivalent reactive powers output by thermal power units and hydropower units; A third calculation module for inputting the per-unit value of the reference angular frequency of the power grid simulation device and the reference voltage of the power grid simulation device into the voltage-current double closed-loop control link to obtain the modulation voltage command, and generating the switching signal of the inverter link of the power grid simulation device according to the modulation voltage command.

5. An electronic device, characterized in that, It includes a processor and a memory, and the processor is used to execute a computer program stored in the memory to implement the power grid equivalent inertia simulation method according to any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by a processor, it implements the power grid equivalent inertia simulation method according to any one of claims 1 to 3.

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