A photovoltaic power station single machine equivalent model parameter identification method and device

Abstract

The application discloses a photovoltaic power station single-machine equivalent model parameter identification method, which is based on a traditional single-machine equivalent model and performs optimization identification on control parameters of a converter, constructs an electromagnetic transient model of the photovoltaic power station according to electrical equipment parameters and an operation scene of the photovoltaic power station, performs parameter identification of the single-machine equivalent model based on the electromagnetic transient model, and determines key parameters to be identified, including equivalent machine parameters, equivalent transformer parameters, equivalent power collection line parameters and equivalent machine control parameters, wherein the equivalent machine control parameters consider the relationship between voltage and current limiting, and the operation state difference of the photovoltaic unit, can effectively solve the equivalent process of photovoltaic units with different types, improve the simulation accuracy of the photovoltaic power station connected to the power grid, and thus provide certain reference significance for the photovoltaic power station connected to the power system.

Description

Technical Field

[0001] This invention pertains to power system station modeling technology, and particularly relates to a method and apparatus for identifying parameters of a single-unit equivalent model of a photovoltaic power station. Background Technology

[0002] Photovoltaic power plants have seen rapid growth in installed capacity in recent years due to their ability to utilize solar energy on a large scale and efficiently, demonstrating promising development prospects. However, large-scale photovoltaic power plants contain numerous photovoltaic power generation units, and establishing detailed models to study their grid-connected characteristics when integrated into the power system presents challenges such as large simulation scale and long simulation times. Furthermore, the single-unit multiplication model commonly used in system-level analysis often leads to misjudgments in system safety and stability analysis results because it cannot accurately simulate the differences in operating states between individual units. Therefore, there is an urgent need to balance accuracy and computational complexity, and to develop a practical and improved method for identifying single-unit equivalent parameters of the electromechanical transient model of photovoltaic power plants using minimal equivalent machines and simple calculation methods. This has become one of the key issues that need to be addressed in power system operation.

[0003] Currently, there are several solutions for electromagnetic transient equivalent modeling of photovoltaic power plants, such as:

[0004] 1. Liu Xingjie et al. published “Equivalent Method of Photovoltaic Power Generation System Model Based on Electrical External Characteristics”, Journal of Electrical Engineering, 2014, 29(10): 231-238. This article converts the dynamic model into a controlled voltage source model with second-order dynamic circuit characteristics based on the analysis of the steady-state and transient external characteristics of the photovoltaic power generation system. It only needs to use the light intensity, temperature and fault information as input to obtain the steady-state output current before and after the fault. After determining the relevant parameters of its dynamic circuit, the entire model is established, thus completing the equivalent method of photovoltaic power generation system model based on electrical external characteristics.

[0005] 2. Yan Kai et al. published “Transient Modeling and Equivalent Value of Photovoltaic Power Generation System” Power System Protection and Control, 2015, 43(1): 1-8. This article introduces the common forms of photovoltaic power station grid connection, establishes a photovoltaic power generation unit model connected to the grid through a single-stage inverter, and uses the electromagnetic transient simulation model of photovoltaic power generation system built on PSCAD / EMTDC. Based on this, an equivalent calculation model of photovoltaic power station composed of photovoltaic power generation units is given.

[0006] 3. Cui Xiaodan et al. published "Online Dynamic Equivalent Method for Large Photovoltaic Power Plants Applicable to Electromechanical Transient Simulation" Electric Power System Automation, 2015, 39(12): 21-26. This article proposes an online dynamic equivalent method for large photovoltaic power plants applicable to electromechanical transient simulation by calculating the inverter cluster index online and performing cluster equivalence, and forming an equivalent scheme based on the cluster index threshold value.

[0007] In summary, most current methods for equivalence of photovoltaic (PV) power plants employ either traditional single-unit equivalence methods or clustering strategies for multi-unit equivalence. However, for equivalence involving PV units of different models, traditional single-unit equivalence methods, due to their inherent limitations, are forced to cluster PV units of the same model within each cluster and perform single-unit equivalence for each group. Multi-unit equivalence methods also typically require finding clustering points based on model division, resulting in cumbersome calculations and poor method versatility. Therefore, there is an urgent need for a practical and improved single-unit equivalence parameter identification method for electromagnetic transient models of PV power plants that balances computational complexity and equivalence accuracy. Summary of the Invention

[0008] Based on this, the present invention aims to propose a method and device for parameter identification of a single-unit equivalent model of a photovoltaic power station. The method performs single-unit equivalent modeling on a photovoltaic power station containing photovoltaic units of different models, and uses the parameters of the photovoltaic power station before the equivalent modeling to identify the parameters of the equivalent model, so that the established single-unit equivalent model can accurately reflect the response characteristics of the actual photovoltaic power station system.

[0009] In a first aspect, the present invention provides a method for identifying parameters of a single-unit equivalent model of a photovoltaic power plant, comprising:

[0010] An electromagnetic transient model of a photovoltaic power station is constructed based on the electrical equipment parameters and operating scenarios of the photovoltaic power station.

[0011] The equivalent parameters of a single machine are identified using an electromagnetic transient model. These equivalent parameters include equivalent machine parameters, equivalent transformer parameters, equivalent collector line parameters, and equivalent machine control parameters.

[0012] The process of identifying the control parameters of the isostat includes:

[0013] A relationship model between voltage and current limiting is established using the converter control parameters of the equivalent photovoltaic power station, and the equivalent machine control parameters are calculated based on the relationship model.

[0014] Furthermore, a relationship model between voltage and current limiting is established using the converter control parameters of the equivalent photovoltaic power station. Based on this relationship model, the equivalent machine control parameters are calculated, including:

[0015] The equivalent control parameters include active current control parameters and reactive current control parameters;

[0016] Obtain the control parameters of the converter in the photovoltaic power station;

[0017] Establish a model relating the low voltage ride-through threshold to the converter voltage, solve the model to determine the relationship between the current limit and the converter voltage, and calculate the active current of the equivalent machine when the current limit is applied.

[0018] Calculate the active current control parameters based on the active current of the equivalent machine.

[0019] Furthermore, the relational model is represented as follows:

[0020]

[0021] in, This represents the active current control parameters. This indicates the reactive current control parameters. Indicates the converter voltage. express, This indicates the low voltage ride-through threshold.

[0022] Furthermore, solving the relational model to determine the relationship between current limiting and converter voltage includes:

[0023] The relational model is converted into an expression for the converter voltage as follows:

[0024] ,

[0025] Solve for the root of the expression for converter voltage, and determine the converter voltage under current limiting based on the root of the expression.

[0026] Furthermore, the equivalent box-type transformer parameters include:

[0027] ,

[0028] in, This indicates the rated capacity of the equivalent transformer. This represents the equivalent impedance of the transformer. This is the equivalent admittance of the transformer. This represents the capacity of the i-th transformer before the equivalent value is reached.

[0029] Furthermore, the equivalent collector line parameters include:

[0030] ,

[0031] in, The electromagnetic current generated by the i-th photovoltaic unit before the equivalent value is given. It is an equivalent electromagnetic pressure. This refers to the low-voltage side voltage of the main transformer in a photovoltaic power station. This is the equivalent collector line impedance. This indicates the rated capacity of the equivalent machine, and the subscript "eq" represents the equivalent machine.

[0032] Furthermore, the equivalent collector circuit parameters also include equivalent positive-sequence resistance and equivalent positive-sequence inductive reactance, and the identification process includes:

[0033] ,

[0034] in, This represents the equivalent positive sequence resistance of the equivalent collector circuit. This represents the equivalent positive sequence inductive reactance of the equivalent collector circuit.

[0035] Furthermore, the oscillator parameters include basic oscillator parameters and oscillator operating parameters. Identification of the oscillator operating parameters includes:

[0036] ,

[0037] Where n represents the number of photovoltaic units of the same model before the equivalent value is reached. For the output of the i-th generator (i=1,2,…,n), This refers to the rated power of a single generator. This refers to the rated capacity of a single generator. The subscript "eq" indicates the equivalent capacity of a photovoltaic unit of the same model.

[0038] Furthermore, the basic parameters of the equivalent machine adopt the basic parameters of the same model of photovoltaic unit before equivalence, including the basic parameters of photovoltaic cells, the basic parameters of converter, the control parameters during voltage ride-through, and the control parameters for voltage recovery.

[0039] Furthermore, the operating scenario adopts a uniform power distribution scenario, represented as follows: , Let i represent the output of the i-th generator (i=1,2,…,n). This represents the total power of the system.

[0040] Secondly, this invention proposes a parameter identification device for a single-unit equivalent model of a photovoltaic power station, comprising:

[0041] The transient modeling module is used to construct an electromagnetic transient model of a photovoltaic power station based on the electrical equipment parameters and operating scenarios of the photovoltaic power station.

[0042] The parameter identification module is used to identify the equivalent parameters of a single machine using an electromagnetic transient model. The equivalent parameters of a single machine include equivalent machine parameters, equivalent transformer parameters, equivalent collector line parameters, and equivalent machine control parameters.

[0043] The process of identifying the control parameters of the isostat includes:

[0044] A relationship model between voltage and current limiting is established using the converter control parameters of the equivalent photovoltaic power station, and the equivalent machine control parameters are calculated based on the relationship model.

[0045] Thirdly, the present invention provides an electronic device including a memory storing computer-executable instructions and a processor, wherein when the computer-executable instructions are executed by the processor, the device performs the various steps of the photovoltaic power plant single-unit equivalent model parameter identification method provided in the first aspect.

[0046] Fourthly, the present invention provides a readable storage medium storing a computer-executable program, which, when executed, can implement the various steps of the photovoltaic power plant single-unit equivalent model parameter identification method provided in the first aspect.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] This invention proposes a parameter identification method for the equivalent model of a single photovoltaic (PV) power plant. Based on the traditional single-unit equivalent model, it optimizes and identifies the control parameters of the converter. An electromagnetic transient model of the PV power plant is constructed according to the electrical equipment parameters and operating scenarios. Based on this electromagnetic transient model, the parameters of the single-unit equivalent model are identified. The key parameters to be identified include equivalent machine parameters, equivalent transformer parameters, equivalent collector line parameters, and equivalent machine control parameters. The equivalent machine control parameters consider the relationship between voltage and current limiting and take into account the differences in the operating states of the PV units. Further embodiments specifically propose methods for identifying these parameters. The parameter identification method proposed in this invention can effectively solve the equivalent process involving different types of PV power generation units, improve the simulation accuracy of PV power plant grid connection, and thus provide a certain reference value for PV power plant grid connection. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0050] Figure 1 This is a flowchart illustrating the implementation of the photovoltaic power plant single-unit equivalent model parameter identification method provided in this embodiment of the invention.

[0051] Figure 2 This is a general structural diagram of the photovoltaic power generation system provided in the embodiments of the present invention;

[0052] Figure 3 This is an electromagnetic transient model architecture diagram of a photovoltaic power station provided in an embodiment of the present invention;

[0053] Figure 4 This is an equivalent model architecture diagram of a single photovoltaic power station provided in an embodiment of the present invention;

[0054] Figure 5 This is a structural diagram of the photovoltaic power plant single-unit equivalent model parameter identification device provided in an embodiment of the present invention;

[0055] Figure 6 This is an electronic device architecture diagram provided for an embodiment of the present invention. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] See Figure 1 An embodiment of the present invention provides a method for identifying parameters of a single-unit equivalent model of a photovoltaic power plant, comprising the following steps:

[0058] Step S110. Construct an electromagnetic transient model of the photovoltaic power station based on the electrical equipment parameters and operating scenarios of the photovoltaic power station.

[0059] The electrical equipment parameters of the photovoltaic power station obtained in this step include the basic parameters of the photovoltaic power station before equivalence, the operating parameters of the photovoltaic power station, the parameters of the transformer substation, the parameters of the main transformer, and the topology and parameters of the power collection network. An electromagnetic transient model of the photovoltaic power station is established using electromagnetic simulation software. Specifically, mathematical models are established for each electrical device in the photovoltaic power station, and the mathematical descriptions of individual devices are coupled into the overall model to form a comprehensive electromagnetic transient model that reflects the dynamic response of the wind farm.

[0060] For example, Figure 2 This diagram illustrates a general structure for a photovoltaic power generation system, which mainly includes a photovoltaic array, a voltage regulator circuit, a converter, and its controller. Figure 3 The diagram illustrates the electromagnetic transient model obtained by modeling a photovoltaic power station.

[0061] Step S120. Use the electromagnetic transient model to identify the equivalent parameters of a single machine, wherein the equivalent parameters of a single machine include equivalent machine parameters, equivalent transformer parameters, equivalent collector line parameters and equivalent machine control parameters;

[0062] The process of identifying the control parameters of the isostat includes:

[0063] A relationship model between voltage and current limiting is established using the converter control parameters of the equivalent photovoltaic power station, and the equivalent machine control parameters are calculated based on the relationship model.

[0064] Specifically, the equivalent machine parameters mainly describe the inertial, damping, and excitation characteristics exhibited by the photovoltaic unit as a power generation device during electromagnetic transient processes. These include basic equivalent machine parameters and operating parameters. The basic equivalent machine parameters are those of the same model of photovoltaic generator before equivalence, including basic parameters of the photovoltaic cells, basic parameters of the converter, control parameters during voltage ride-through, voltage recovery control parameters, and other necessary parameters. Further implementation methods, to maximize modeling accuracy, should use refined modeling parameters of the corresponding photovoltaic generator model, rather than the default parameters provided by the electromagnetic simulation software.

[0065] In a further embodiment, the identification of the equivalent machine operating parameters includes:

[0066] ,

[0067] Where n represents the number of photovoltaic units of the same model before the equivalent value is reached. For the output of the i-th generator (i=1,2,…,n), This refers to the rated power of a single generator. This refers to the rated capacity of a single generator. The subscript "eq" indicates the equivalent capacity of a photovoltaic unit of the same model.

[0068] The equivalent box transformer parameters include:

[0069] ,

[0070] in, This indicates the rated capacity of the equivalent transformer. This represents the equivalent impedance of the transformer. This is the equivalent admittance of the transformer. This represents the capacity of the i-th transformer before the equivalent value is reached.

[0071] Equivalent collector line parameters include:

[0072] ,

[0073] in, The electromagnetic current generated by the i-th photovoltaic unit before the equivalent value is given. It is an equivalent electromagnetic pressure. This refers to the low-voltage side voltage of the main transformer in a photovoltaic power station. This is the equivalent collector line impedance. This indicates the rated capacity of the equivalent machine, and the subscript "eq" represents the equivalent machine.

[0074] Furthermore, the equivalent collector circuit parameters also include equivalent positive-sequence resistance and equivalent positive-sequence inductive reactance, and the identification process includes:

[0075] ,

[0076] in, This represents the equivalent positive sequence resistance of the equivalent collector circuit. This represents the equivalent positive sequence inductive reactance of the equivalent collector circuit.

[0077] Furthermore, embodiments of the present invention also provide identification of equivalent machine control parameters, which mainly include active and reactive power regulation coefficients, voltage regulation and low-voltage ride-through parameters, and parameters describing dynamic response characteristics (such as damping coefficients and virtual inertia). These parameters respectively reflect the dynamic behavior of the photovoltaic power station as an equivalent machine in the power grid in terms of power output balance, voltage regulation response, and when encountering grid faults (such as low-voltage ride-through). Among them, the active and reactive power control parameters describe how the photovoltaic power station adjusts its output active and reactive power under different operating conditions to maintain system power balance and stability.

[0078] The equivalent control parameters include active current control parameters and reactive current control parameters, and their identification process includes:

[0079] Obtain the control parameters of the converter in the photovoltaic power station;

[0080] Establish a model relating the low voltage ride-through threshold to the converter voltage, solve the model to determine the relationship between the current limit and the converter voltage, and calculate the active current of the equivalent machine when the current limit is applied.

[0081] Calculate the active current control parameters based on the active current of the equivalent machine.

[0082] According to the low voltage ride-through mechanism, the converter will operate when the grid voltage drops to a predetermined threshold. When the current limit is applied, the system will enter a protection state, triggering current limiting measures. Modeling this system requires considering the low-voltage ride-through trigger condition, the controller's response characteristics, and the current limiting strategy. By describing the relationship between converter voltage and current limiting using mathematical equations, and leveraging the converter's dynamic characteristics and control algorithm, a mapping relationship is established using the low-voltage ride-through threshold as the trigger point. This illustrates how the magnitude and behavior of the current limiting change under different voltages.

[0083] Specifically, in the electromagnetic transient model, when the active current of the converter reaches the limit, the following relationship exists:

[0084]

[0085] in, This represents the active current control parameters. This indicates the reactive current control parameters. Indicates the converter voltage. This indicates the maximum allowable current of the converter during a fault. This indicates the low voltage ride-through threshold.

[0086] Convert the above formula to a formula relating voltage The expression is as follows:

[0087]

[0088] Using the discriminant of a quadratic equation, when the above equation has two distinct roots, i.e., Δ>0, then we have:

[0089]

[0090] Simplified to:

[0091]

[0092] If there exist two unequal roots, then the above statement regarding voltage applies between the two roots. If the expression is less than 0, the fault control uses an unlimited specified current. If the equation is greater than 0 outside the two roots, the fault control switches to limit control.

[0093] Using Vieta's formulas for quadratic equations, we have the following expression:

[0094]

[0095]

[0096] It can be seen that if the equation has roots, there must be one root greater than 0. That is, under the specified control parameters of active current and reactive current, it is possible to directly determine whether there is a voltage drop that causes the wind turbine to switch between limited and unlimited voltage.

[0097] The solution to the above equation is:

[0098]

[0099] It can be seen that, based on the known control parameters of the photovoltaic unit, the voltage threshold in the current limiting stage can be calculated.

[0100] Once the voltage threshold is known, the voltage values ​​at the outlet of all wind turbine units can be calculated using the collector network. After identifying the photovoltaic units under limiting conditions, the active current of the photovoltaic units in the single-unit equivalent model is calculated as follows:

[0101]

[0102] in, This represents the active current value in the single-machine equivalent model. This indicates that the active current limit has not been reached. Indicates the unit that reaches the active current limit.

[0103] Therefore, the active current control parameters in the single-machine equivalent model can be calculated as follows:

[0104]

[0105] Where, Indicates the equivalent converter voltage.

[0106] In a further embodiment, when the wind farm does not provide an operating scenario, a uniform power distribution scenario is adopted, denoted as , Indicates the output of the i-th generator, (i = 1, 2,..., n), Indicates the total power of the system.

[0107] Furthermore, after completing the parameter identification, the single-machine equivalent model constructed can be verified through the following steps, specifically including:

[0108] (1) Verification under different light intensity scenarios: Set the power generated by all photovoltaic power generation units in the photovoltaic power station to be high power (P > 0.7Pn), medium power (0.4Pn < P < 0.7Pn), low power (0.2Pn < P < 0.4Pn), and full power (0.2Pn < P < 0.9Pn) scenarios respectively. The fault duration is set according to the voltage dip conditions in the low voltage ride-through detection report of the corresponding model photovoltaic power generation unit. Verify the voltage, current, active power, and reactive power response curves at the outlet of the photovoltaic power station for the detailed model, traditional single-machine equivalent model, and the single-machine equivalent model established in the embodiment of the present invention.

[0109] (2) Verification under different voltage dip scenarios: Set the voltage dip degree at the grid connection point to be 0.2 p.u., 0.35 p.u., 0.5 p.u., 0.75 p.u., and 0.9 p.u. The fault duration is set according to the voltage dip conditions in the low voltage ride-through detection report of the corresponding model photovoltaic power generation unit. Verify the voltage, current, active power, and reactive power response curves at the outlet of the photovoltaic power station for the detailed model, traditional single-machine equivalent model, and the single-machine equivalent model established in the embodiment of the present invention.

[0110] Exemplarily, Figure 4 Schematically shows the single-machine equivalent model of the photovoltaic power station established by using the method provided in the embodiment of the present invention.

[0111] The above embodiments provide a method for parameter identification of the equivalent model of a single photovoltaic power plant unit. Based on the traditional single-unit equivalent model, the method optimizes and identifies the control parameters of the converter. An electromagnetic transient model of the photovoltaic power plant is constructed according to the electrical equipment parameters and operating scenarios. Based on the electromagnetic transient model, the parameters of the single-unit equivalent model are identified. The key parameters to be identified include equivalent machine parameters, equivalent transformer parameters, equivalent collector line parameters, and equivalent machine control parameters. The equivalent machine control parameters consider the relationship between voltage and current limiting and take into account the differences in the operating states of the photovoltaic units. Further embodiments specifically propose methods for identifying these parameters. The parameter identification method proposed in this invention can effectively solve the equivalent process involving photovoltaic power generation units of different models, improve the simulation accuracy of photovoltaic power plant grid connection, and thus provide a certain reference value for photovoltaic power plant grid connection.

[0112] The disclosed method can be implemented using various types of devices. Therefore, the present invention also discloses a parameter identification device corresponding to the above method. Specific embodiments are given below for detailed description.

[0113] like Figure 5 As shown, one embodiment of the present invention provides a parameter identification device for a single-unit equivalent model of a photovoltaic power station, comprising:

[0114] Transient modeling module 502 is used to construct an electromagnetic transient model of a photovoltaic power station based on the electrical equipment parameters and operating scenarios of the photovoltaic power station.

[0115] The parameter identification module 504 is used to identify the equivalent parameters of a single machine using an electromagnetic transient model. The equivalent parameters of a single machine include equivalent machine parameters, equivalent transformer parameters, equivalent collector line parameters, and equivalent machine control parameters.

[0116] The process of identifying the control parameters of the isostat includes:

[0117] A relationship model between voltage and current limiting is established using the converter control parameters of the equivalent photovoltaic power station, and the equivalent machine control parameters are calculated based on the relationship model.

[0118] The device provided in this application embodiment has the same implementation principle and technical effect as the aforementioned method embodiment. For the sake of brevity, any parts not mentioned in the device embodiment can be referred to the corresponding content in the aforementioned method embodiment.

[0119] The methods and related apparatuses mentioned in the above embodiments are described with reference to the method flowcharts and / or structural diagrams provided in the embodiments of this application. Specifically, each block of the method flowchart and / or structural diagram, as well as combinations of blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, generate instructions for implementing the process. Figure 1 A schematic diagram of one or more processes and / or structures. Figure 1 The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 A schematic diagram of one or more processes and / or structures. Figure 1 The functions specified in one or more boxes. These computer program instructions may 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, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 A process or multiple processes and / or structures illustrate the steps of the functions specified in one or more boxes.

[0120] The following embodiments illustrate the application of this method to a computer device. It is understood that the computer device can be any device with computing and processing capabilities, including but not limited to servers or personal laptops. In one embodiment, the computer device can be an application server, which can be a server used to run the application under test.

[0121] See Figure 6 This document illustrates a hardware block diagram of an electronic device intended to represent various forms of digital computers, such as laptops, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframes, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the present application described and / or claimed herein.

[0122] like Figure 6As shown, the electronic device includes: at least one processor 1, at least one communication interface 2, at least one memory 3, and at least one communication bus 4;

[0123] In this embodiment of the application, the number of processor 1, communication interface 2, memory 3, and communication bus 4 is at least one, and processor 1, communication interface 2, and memory 3 communicate with each other through communication bus 4;

[0124] Processor 1 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention.

[0125] Memory 3 may include high-speed RAM, and may also include non-volatile memory, such as at least one disk storage device;

[0126] The memory stores a program, and the processor can call the program stored in the memory. The program is used to implement the various processing steps of the aforementioned photovoltaic power station single-unit equivalent model parameter identification scheme.

[0127] This invention also provides a readable storage medium storing a computer program thereon. When the computer program is executed by a processor, it implements various processing flows of the photovoltaic power plant single-unit equivalent model parameter identification scheme provided in any possible implementation of the above embodiments and / or in combination with the embodiments.

[0128] The invention has been described in particular detail above with respect to possible scenarios, and those skilled in the art will recognize that the invention can be practiced through other embodiments. Specific naming of components, capitalization of terms, attributes, data structures, or any other programming or structural aspects are not mandatory or important, and the mechanisms or features of implementing the invention may have different names, forms, or procedures. The system can be implemented through a combination of hardware and software (as described), entirely through hardware elements, or entirely through software elements. The specific division of functions among the various system components described herein is merely exemplary and not mandatory; rather, the functions performed by a single system component can be performed by multiple components, or the functions performed by multiple components can be performed by a single component.

[0129] Those skilled in the art should understand that the various steps of the disclosed methods can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using device-executable program code, which can then be stored in a storage device for execution by the computing device. Alternatively, they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Therefore, the embodiments disclosed in this invention are not limited to any specific hardware and software combination.

[0130] The programs (also referred to as programs, software, software applications, or code) executable by these computing devices include machine instructions of a programmable processor and can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. As used herein, the terms “machine-readable medium” and “computer-readable medium” refer to any computer program product, device, and / or apparatus (e.g., disk, optical disk, memory, programmable logic device (PLD)) used to provide machine instructions and / or data to a programmable processor, including machine-readable media that receive machine instructions as machine-readable signals. The term “machine-readable signal” refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0131] Certain aspects of this invention include the process steps and instructions described herein in algorithmic form. It should be noted that the process steps and instructions of this invention can be implemented in software, firmware, and / or hardware, and when implemented in software, they can be downloaded, stored on various operating systems and operated from said platforms.

[0132] Those skilled in the art will understand that the structures shown in the figures are merely block diagrams of some structures related to the present application and do not constitute a limitation on the terminal device to which the present application is applied. Specific terminal devices may include more or fewer components than those shown in the figures, or combine certain components, or have different component arrangements.

[0133] In the description of this specification, the use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "possible design," etc., refers to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0134] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for identifying parameters of a single-unit equivalent model of a photovoltaic power plant, characterized in that, include: An electromagnetic transient model of a photovoltaic power station is constructed based on the electrical equipment parameters and operating scenarios of the photovoltaic power station. The electromagnetic transient model is used to identify the equivalent parameters of a single machine, which include equivalent machine parameters, equivalent transformer parameters, equivalent collector line parameters, and equivalent machine control parameters. The identification process of the equivalent machine control parameters includes: The equivalent control parameters include active current control parameters and reactive current control parameters. Using the converter control parameters of the photovoltaic power station before the equivalent control, the following relationship model between voltage and current limiting is established: ； in, This represents the active current control parameters. This indicates the reactive current control parameters. Indicates the converter voltage. This indicates the maximum allowable current during a converter fault. Indicates the low voltage ride-through threshold; The relationship model is converted into the following relationship with respect to voltage. Solve the quadratic equation in one variable: ； The roots of the quadratic equation in one variable can be found using Vieta's formulas as follows: ； Based on the roots of the quadratic equation, and given the control parameters of the photovoltaic units, the converter voltage threshold in the current limiting stage can be calculated. Once the known converter voltage threshold is determined, the voltage values ​​at the outlets of all units can be calculated using the collector network. After identifying the photovoltaic units under current limiting, the active current of the equivalent machine is calculated as follows: ； in, This represents the active current value in the single-machine equivalent model. These are the active current control parameters during a fault. Let be the port voltage of the i-th unit. Let j be the maximum allowable current value for the j-th generating unit. Let be the reactive current value of the j-th generating unit during the fault period. This indicates that the active current limit has not been reached. This indicates the generator unit that has reached the active current limit; The active current control parameters are calculated based on the active current of the equivalent machine as follows: ； in, This represents the active current control parameters of the single-machine equivalent model. This represents the equivalent converter voltage.

2. The method according to claim 1, characterized in that, The equivalent box-type transformer parameters include: ， in, This indicates the rated capacity of the equivalent transformer. This represents the equivalent impedance of the transformer. This represents the impedance of the i-th transformer before the equivalent value is obtained. This is the equivalent admittance of the transformer. Let represent the admittance of the i-th transformer before the equivalent value. This represents the capacity of the i-th transformer before the equivalent value is reached.

3. The method according to claim 1, characterized in that, The equivalent collector line parameters include: ， in, The electromagnetic current generated by the i-th photovoltaic unit before the equivalent value is given. It is an equivalent electromagnetic pressure. This refers to the low-voltage side voltage of the main transformer in a photovoltaic power station. This is the equivalent collector line impedance. This indicates the rated capacity of the equivalent machine, and the subscript "eq" represents the equivalent machine.

4. The method according to claim 3, characterized in that, The equivalent collector circuit parameters also include equivalent positive-sequence resistance and equivalent positive-sequence inductive reactance, and the identification process includes: ， in, This represents the equivalent positive sequence resistance of the equivalent collector circuit. This represents the equivalent positive sequence inductive reactance of the equivalent collector circuit.

5. The method according to claim 1, characterized in that, The grading machine parameters include basic grading machine parameters and grading machine operating parameters. Identification of the grading machine operating parameters includes: ， Where n represents the number of photovoltaic units of the same model before the equivalent value is reached. For the output of the i-th generator, i=1,2,…,n, This refers to the rated power of a single generator. This refers to the rated capacity of a single generator. The subscript "eq" indicates the equivalent capacity of a photovoltaic unit of the same model. This indicates the output of the equalization machine. This indicates the rated power of the equalization machine. This indicates the rated capacity of the equalization machine.

6. A parameter identification device for a single-unit equivalent model of a photovoltaic power station, characterized in that, include: The transient modeling module is used to construct an electromagnetic transient model of a photovoltaic power station based on the electrical equipment parameters and operating scenarios of the photovoltaic power station. The parameter identification module is used to identify the equivalent parameters of a single machine using an electromagnetic transient model. The equivalent parameters of a single machine include equivalent machine parameters, equivalent transformer parameters, equivalent collector line parameters, and equivalent machine control parameters. The identification process of the equivalent machine control parameters includes: The equivalent control parameters include active current control parameters and reactive current control parameters. Using the converter control parameters of the photovoltaic power station before the equivalent control, the following relationship model between voltage and current limiting is established: ； in, This represents the active current control parameters. This indicates the reactive current control parameters. Indicates the converter voltage. This indicates the maximum allowable current during a converter fault. Indicates the low voltage ride-through threshold; The relationship model is converted into the following relationship with respect to voltage. Solve the quadratic equation in one variable: ； The roots of the quadratic equation in one variable can be found using Vieta's formulas as follows: ； Based on the roots of the quadratic equation, and given the control parameters of the photovoltaic units, the converter voltage threshold in the current limiting stage can be calculated. Once the known converter voltage threshold is determined, the voltage values ​​at the outlets of all units can be calculated using the collector network. After identifying the photovoltaic units under current limiting, the active current of the equivalent machine is calculated as follows: ； in, This represents the active current value in the single-machine equivalent model. These are the active current control parameters during a fault. Let be the port voltage of the i-th unit. Let j be the maximum allowable current value for the j-th generating unit. Let be the reactive current value of the j-th generating unit during the fault period. This indicates that the active current limit has not been reached. This indicates the generator unit that has reached the active current limit; The active current control parameters are calculated based on the active current of the equivalent machine as follows: ； in, This represents the active current control parameters of the single-machine equivalent model. This represents the equivalent converter voltage.

7. An electronic device, characterized in that, It includes a memory storing computer-executable instructions and a processor, which, when executed by the processor, causes the device to perform the photovoltaic power plant single-unit equivalent model parameter identification method as described in any one of claims 1 to 5.

8. A readable storage medium, characterized in that, It stores a computer-executable program, which, when executed, can implement the method for identifying parameters of a single-unit equivalent model of a photovoltaic power station as described in any one of claims 1 to 5.

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