Method and system for obtaining grid-connected impedance equivalent value of new energy stations with network structure preservation

Abstract

The present invention discloses a method and system for obtaining the equivalent value of grid-connected impedance of a new energy station with network structure preservation. Aiming at the complex multi-level radial hybrid network topology in the new energy station, based on the voltage characteristic clustering results of the power generation unit during high voltage ride-through or low voltage ride-through, and taking the equal power loss before and after the equivalent value as the basic principle, a method for calculating the equivalent value of grid-connected impedance of a new energy station with network structure preservation is proposed. The present invention does not rely on real-time operation data, well maintains the structural characteristics of the electrical network in the station, retains the interaction between equivalent subclasses, makes the equivalent value of impedance of complex new energy stations feasible, has a small equivalent error and a high equivalent accuracy, and is conducive to promoting the grid connection and consumption of new energy.

Description

Technical Field

[0001] The present invention belongs to the technical field of simulation modeling of new energy stations, and specifically relates to a method and system for obtaining grid-connected impedance equivalent values ​​of new energy stations with network structure preservation. Background Art

[0002] The scale of new energy installed capacity is growing rapidly. The number of power electronic power generation equipment is huge, the control is complex, and the interaction between equipment is serious. New energy stations and power networks and other stations show multi-time scale coupling characteristics. The dynamic interaction between them is becoming increasingly prominent, and the system presents large time-frequency span oscillation characteristics. One of the important means to analyze and solve these problems is to conduct multi-time scale modeling and simulation of new energy stations. In order to simulate and calculate tens of thousands of power electronic equipment in the system at the same time, the stations must first be equalized.

[0003] However, due to the different geographical environments of new energy stations, for the sake of production economy, the power network within the station is mainly a multi-level radial hybrid structure with obvious differences in impedance distribution characteristics. Therefore, there is an urgent need for a set of station grid-connected impedance equivalence methods that are widely applicable to electromechanical transient modeling and simulation of new energy stations. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for obtaining grid-connected impedance equivalent values ​​of new energy stations with network structure preservation, which solves the problems existing in the prior art.

[0005] The present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for obtaining a grid-connected impedance equivalent value of a new energy station with a network structure maintained, comprising:

[0007] Acquire electrical operation data in the new energy station, where the electrical operation data is data pre-stored in a database or data collected in real time;

[0008] The relationship between the equivalent grid-connected impedance and the original network impedance is obtained, and based on the electrical operation data and the relationship, the grid-connected impedance of the new energy station is obtained.

[0009] Furthermore, the electrical operation data within the new energy station includes the electrical topology structure within the station, the impedance of each line, the impedance of the box transformer, the terminal voltage of the power generation unit and the rated current of the power generation unit.

[0010] Furthermore, the relationship between the equivalent grid-connected impedance and the original network impedance is obtained, including:

[0011] Obtain the steady-state value U of the terminal voltage of each power generation unit when high voltage ride-through or low voltage ride-through is in full power condition of the new energy station i ;

[0012] The clustering algorithm is used to calculate the steady-state voltage value U of each generating unit. i Divide into multiple subclasses and obtain clustering results;

[0013] According to the clustering results, the relative electrical topological relationship between each subclass is obtained;

[0014] Perform impedance equalization on each subclass, and obtain the equivalent impedance of each subclass based on the principle that the power loss before and after equalization is equal;

[0015] According to the equivalent impedance of each subclass and the relative electrical topological relationship between each subclass, the equivalent grid-connected impedance of the new energy station is obtained, and the relationship between the equivalent grid-connected impedance and the original network impedance is constructed.

[0016] Furthermore, the clustering algorithm adopts K-means algorithm.

[0017] Furthermore, according to the principle that the power loss before and after the equalization is equal, the equivalent impedance of each subclass is obtained as follows:

[0018]

[0019] Among them, Z eq_k represents the equivalent impedance corresponding to the k-th subclass; the original network corresponding to the k-th subclass contains K impedances; Z k_j represents the jth impedance in the kth class, which is the line impedance or the sum of the line impedance and the box-type transformer impedance; Indicates flow through Z k_j The current I eq_k Represents the total rated current of the generating units contained in the kth category; I eq_k_in Represents the input current of the kth class.

[0020] Furthermore, according to the equivalent impedance of each subclass and the relative electrical topological relationship between each subclass, the equivalent grid-connected impedance of the new energy station is obtained, including: according to the relative electrical topological relationship between each subclass, the equivalent impedance of each subclass is connected to obtain the equivalent grid-connected impedance of the new energy station.

[0021] In a second aspect, the present invention provides a network structure-maintained new energy station grid-connected impedance equivalent acquisition system, including an operation data module and a grid-connected impedance acquisition module;

[0022] The operation data module is used to obtain the electrical operation data in the new energy station, and the electrical operation data is data pre-stored in the database or data collected in real time;

[0023] The grid-connected impedance acquisition module is used to obtain the relationship between the equivalent grid-connected impedance and the original network impedance, and to obtain the grid-connected impedance of the new energy station based on the electrical operation data and the relationship.

[0024] Further, the grid-connected impedance acquisition module includes a relationship acquisition unit and a grid-connected impedance acquisition unit;

[0025] The relationship acquisition unit is used to obtain the terminal voltage steady-state value U of each power generation unit when the high voltage ride-through or low voltage ride-through is under the condition of full power generation of the new energy station. i ;

[0026] The clustering algorithm is used to calculate the steady-state voltage value U of each generating unit. i Divide into multiple subclasses and obtain clustering results;

[0027] According to the clustering results, the relative electrical topological relationship between each subclass is obtained;

[0028] Perform impedance equalization on each subclass, and obtain the equivalent impedance of each subclass based on the principle that the power loss before and after equalization is equal;

[0029] According to the equivalent impedance of each subclass and the relative electrical topological relationship between each subclass, the equivalent grid-connected impedance of the new energy station is obtained, and the relationship between the equivalent grid-connected impedance and the original network impedance is constructed;

[0030] The grid-connected impedance acquisition unit is used to acquire the grid-connected impedance of the new energy station based on the electrical operation data and the relationship.

[0031] Furthermore, the clustering algorithm adopts K-means algorithm.

[0032] Furthermore, according to the principle that the power loss before and after the equalization is equal, the equivalent impedance of each subclass is obtained as follows:

[0033]

[0034] Among them, Z eq_k represents the equivalent impedance corresponding to the k-th subclass; the original network corresponding to the k-th subclass contains K impedances; Z k_j represents the jth impedance in the kth class, which is the line impedance or the sum of the line impedance and the box-type transformer impedance; Indicates flow through Z k_j The current I eq_k Represents the total rated current of the generating units contained in the kth category; I eq_k_in Represents the input current of the kth class.

[0035] The present invention provides a method and system for obtaining the equivalent value of grid-connected impedance of a new energy station with network structure preservation, which takes into account the voltage feature clustering and the equality of power loss equivalent values ​​before and after during high voltage crossing or low voltage crossing, and does not rely on real-time operation data (such as real-time power and real-time current, etc.), and well maintains the structural characteristics of the electrical network in the station, retains the interaction between equivalent subclasses, and makes the equivalent value of impedance of complex new energy stations feasible, with a small equivalent error and a high equivalent accuracy, which is conducive to promoting the grid connection and consumption of new energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0037] Figure 1 A flowchart of a method for obtaining a grid-connected impedance equivalent value of a new energy station with network structure preservation provided by an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of grid connection and classification of rated output of power generation units through different impedances provided in an embodiment of the present invention.

[0039] Figure 3 This is a schematic diagram of the equivalent value of a new energy station provided in an embodiment of the present invention.

[0040] Figure 4 A schematic diagram of the structure of a system for acquiring grid-connected impedance equivalent values ​​of a new energy station with network structure preservation provided by an embodiment of the present invention;

[0041] Marks and corresponding parts names in the attached drawings:

[0042] Among them, 1-operation data module, 2-grid impedance acquisition module. DETAILED DESCRIPTION

[0043] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0044] Example 1

[0045] like Figure 1 As shown, the present invention provides a method for obtaining a grid-connected impedance equivalent value of a new energy station with a network structure maintained, comprising:

[0046] S1. Obtain electrical operation data in a new energy station, where the electrical operation data is data pre-stored in a database or data collected in real time.

[0047] S2. Obtain the relationship between the equivalent grid-connected impedance and the original network impedance, and obtain the grid-connected impedance of the new energy station based on the electrical operation data and the relationship.

[0048] The relationship between the equivalent grid-connected impedance and the original network impedance is determined by an equivalent grid-connected impedance algorithm.

[0049] The equivalent grid-connected impedance algorithm is based on the basic principle that the power loss before and after the equivalent value is equal, and the relative electrical topological relationship between the equivalent parts is kept unchanged.

[0050] In a possible real-time manner, the electrical operation data in the new energy station includes the electrical topology structure in the station, the impedance of each line, the impedance of the box transformer, the terminal voltage of the power generation unit and the rated current of the power generation unit.

[0051] Optionally, the power generation unit refers to a device used for power generation in an energy station, for example, the power generation unit may be a wind turbine and a photovoltaic inverter. It is worth noting that in addition to the above-mentioned power generation equipment, the power generation unit may also be set as other power generation equipment, which will not be described one by one here.

[0052] In a possible real-time manner, the relationship between the equivalent grid impedance and the original network impedance is obtained, including:

[0053] Obtain the steady-state value U of the terminal voltage of each power generation unit when high voltage ride-through or low voltage ride-through is in full power condition of the new energy station i . i=1,2,…,N, where N represents the total number of power generation units.

[0054] The clustering algorithm is used to calculate the steady-state voltage value U of each generating unit. i Divide into multiple subclasses and obtain clustering results.

[0055] In this embodiment, the steady-state value of the terminal voltage U of each power generation unit can be i The data are divided into M categories, and the value range of M can be [1, 4]. It is worth noting that the value range of M here is only an example and is not a limitation to M. M can also be other values.

[0056] According to the clustering results, the relative electrical topological relationship between each subclass is obtained. The electrical operation data includes the electrical topological structure within the station. Therefore, the series and parallel relationship between subclasses can be determined based on the electrical topological structure within the station and the current flow direction of the circuit principle, thereby obtaining the relative electrical topological relationship between each subclass.

[0057] Equalize the kth (k = 1, 2, ..., M) class, and obtain the equivalent impedance Z of each subclass based on the principle that the power loss before and after equalization is equal eq_k .

[0058] According to the equivalent impedance of each subclass and the relative electrical topological relationship between each subclass, the equivalent grid-connected impedance of the new energy station is obtained, and the relationship between the equivalent grid-connected impedance and the original network impedance is constructed.

[0059] In a possible real-time manner, the clustering algorithm adopts K-means algorithm.

[0060] This embodiment takes the connection of multiple power generation units of the same model to the grid in a complex network structure as an example to illustrate the technical solution provided by the present invention.

[0061] like Figure 2 As shown in the figure, by obtaining the steady-state value of the terminal voltage of each power generation unit when high voltage ride-through or low voltage ride-through occurs under the condition of full power generation of the new energy station, and classifying the steady-state value of the terminal voltage of each power generation unit based on the K-means classification algorithm, the power generation units are divided into three categories.

[0062] According to the calculation formula of various equivalent impedances, various equivalent impedances are calculated as follows:

[0063] Category 1:

[0064]

[0065] Category 2:

[0066]

[0067] 3 categories:

[0068]

[0069] In the formula, I1~I 14 is the rated current of each generating unit.

[0070] According to the relative electrical topological relationship between Class 1, Class 2 and Class 3, the equivalent grid-connected impedance of the new energy station is given by Z eq_1 , Z eq_2 and Z eq_3 The specific network topology is as follows: Figure 3 shown.

[0071] In a possible real-time method, based on the principle that the power loss before and after the equalization is equal, the equivalent impedance of each subclass is obtained as follows:

[0072]

[0073] Among them, Z eq_krepresents the equivalent impedance corresponding to the k-th subclass; the original network corresponding to the k-th subclass contains K impedances; Z k_j represents the jth impedance in the kth class, which is the line impedance or the sum of the line impedance and the box-type transformer impedance; Indicates flow through Z k_j The current I eq_k Represents the total rated current of the generating units contained in the kth category; I eq_k_in Represents the input current of the kth category.

[0074] In a possible real-time method, the equivalent grid-connected impedance of the new energy station is obtained according to the equivalent impedance of each subclass and the relative electrical topological relationship between each subclass, including: according to the relative electrical topological relationship between each subclass, the equivalent impedance of each subclass is connected (that is, the equivalent impedance is connected in series and parallel according to the relative electrical topological relationship) to obtain the equivalent grid-connected impedance of the new energy station.

[0075] The present embodiment provides a method for obtaining the equivalent value of the grid-connected impedance of a new energy station with network structure preservation, which takes into account the voltage feature clustering and the equality of the power loss equivalent value before and after during high voltage crossing or low voltage crossing, and does not rely on real-time operation data (such as real-time power and real-time current, etc.), and well preserves the structural characteristics of the electrical network within the station, retains the interaction between equivalent subclasses, and makes the impedance equivalent of complex new energy stations feasible, with a small equivalent error and a high equivalent accuracy, which is conducive to promoting the grid connection and consumption of new energy.

[0076] Example 2

[0077] like Figure 4 As shown, the present invention provides a network structure-maintained new energy station grid-connected impedance equivalent acquisition system, including an operation data module 1 and a grid-connected impedance acquisition module 2.

[0078] The operation data module 1 is used to obtain the electrical operation data in the new energy station, and the electrical operation data is data pre-stored in the database or data collected in real time.

[0079] The grid-connected impedance acquisition module 2 is used to obtain the relationship between the equivalent grid-connected impedance and the original network impedance, and to obtain the grid-connected impedance of the new energy station based on the electrical operation data and the relationship.

[0080] In a possible real-time manner, the grid-connected impedance acquisition module includes a relationship acquisition unit 21 and a grid-connected impedance acquisition unit 22. The relationship acquisition unit 21 includes a voltage steady-state value acquisition subunit, a clustering unit, a topology relationship acquisition subunit, an equivalent impedance acquisition subunit and a relationship construction subunit.

[0081] The voltage steady-state value acquisition subunit is used to obtain the terminal voltage steady-state value U of each generating unit when the new energy station is fully powered and the high voltage ride-through or low voltage ride-through occurs. i .

[0082] The clustering unit is used to use the clustering algorithm to calculate the terminal voltage steady-state value U of each generating unit. i Divide into multiple subclasses and obtain clustering results.

[0083] The topology relationship acquisition subunit is used to acquire the relative electrical topology relationship between each subclass according to the clustering result.

[0084] The equivalent impedance acquisition subunit is used to perform impedance equalization on each subclass, and obtain the equivalent impedance of each subclass based on the principle that the power loss before and after the equalization is equal.

[0085] The relationship building subunit is used to obtain the equivalent grid-connected impedance of the new energy station according to the equivalent impedance of each subclass and the relative electrical topological relationship between each subclass, and complete the construction of the relationship between the equivalent grid-connected impedance and the original network impedance.

[0086] The grid-connected impedance acquisition unit is used to acquire the grid-connected impedance of the new energy station based on the electrical operation data and the relationship.

[0087] In a possible real-time manner, the clustering algorithm adopts K-means algorithm.

[0088] In a possible real-time method, based on the principle that the power loss before and after the equalization is equal, the equivalent impedance of each subclass is obtained as follows:

[0089]

[0090] Among them, Z eq_k represents the equivalent impedance corresponding to the k-th subclass; the original network corresponding to the k-th subclass contains K impedances; Z k_j represents the jth impedance in the kth class, which is the line impedance or the sum of the line impedance and the box-type transformer impedance; Indicates flow through Z k_j The current I eq_k Represents the total rated current of the generating units contained in the kth category; I eq_k_in Represents the input current of the kth class.

[0091] The network structure-maintained new energy station grid-connected impedance equivalent acquisition system provided in this embodiment can execute the method and technical solution described in Example 1, and the beneficial effects produced are similar and will not be repeated here.

[0092] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0093] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes 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, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0094] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0095] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0096] A person of ordinary skill in the art can understand that all or part of the steps in realizing the above-mentioned facts and methods can be completed by instructing the relevant hardware through a program, and the program involved or the program described can be stored in a computer-readable storage medium. When the program is executed, it includes the following steps: At this time, the corresponding method steps are derived, and the storage medium can be ROM / RAM, a disk, an optical disk, etc.

[0097] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for obtaining the equivalent value of grid-connected impedance of a new energy station with network structure preservation, characterized in that: include: Acquire electrical operation data in the new energy station, where the electrical operation data is data pre-stored in a database or data collected in real time; Obtaining the relationship between the equivalent grid-connected impedance and the original network impedance, and obtaining the grid-connected impedance of the new energy station based on the electrical operation data and the relationship; The operation data of the new energy station includes the electrical topology structure of the station, the impedance of each line, the impedance of the box transformer, the terminal voltage of the power generation unit and the rated current of the power generation unit; Obtain the relationship between the equivalent grid-connected impedance and the original network impedance, including: Obtain the steady-state voltage value U of each power generation unit when the new energy station is fully powered at high voltage ride-through or low voltage ride-through i ; The clustering algorithm is used to calculate the steady-state voltage value U of each generating unit. i Divide into multiple subclasses and obtain clustering results; According to the clustering results, the relative electrical topological relationship between each subclass is obtained; the impedance of each subclass is equalized, and according to the principle that the power loss before and after the equalization is equal, the equivalent impedance of each subclass is obtained; According to the equivalent impedance of each subclass and the relative electrical topological relationship between each subclass, the equivalent grid-connected impedance of the new energy station is obtained, and the relationship between the equivalent grid-connected impedance and the original network impedance is constructed; According to the principle that the power loss before and after equalization is equal, the equivalent impedance of each subclass is obtained as follows: Among them, Z eq_k is the equivalent impedance of the kth class; the kth class corresponds to the original network containing K impedances, Z k_j is the jth impedance in the kth class, I k_j For flow through Z k_j The current I eq_k I is the total rated current of the generating units contained in the kth category, which can be determined according to the rated current values ​​of the generating units after classification; eq_k_in is the input current of the kth class.

2. The method for obtaining the equivalent value of the grid-connected impedance of a new energy station maintained by the network structure according to claim 1, characterized in that: The clustering algorithm adopts K-means algorithm.

3. The method for obtaining the equivalent value of the grid-connected impedance of a new energy station maintained by the network structure according to claim 1, characterized in that: According to the equivalent impedance of each subclass and the relative electrical topological relationship between each subclass, the equivalent grid-connected impedance of the new energy site is obtained, including: according to the relative electrical topological relationship between each subclass, the equivalent impedance of each subclass is connected to obtain the equivalent grid-connected impedance of the new energy site.

4. A network structure-maintained new energy station grid-connected impedance equivalent acquisition system, characterized in that: Including operation data module and grid impedance acquisition module; The operation data module is used to obtain the electrical operation data in the new energy station, and the electrical operation data is data pre-stored in the database or data collected in real time; The grid-connected impedance acquisition module is used to obtain the relationship between the equivalent grid-connected impedance and the original network impedance, and to obtain the grid-connected impedance of the new energy station based on the electrical operation data and the relationship; The grid-connected impedance acquisition module includes a relationship acquisition unit and a grid-connected impedance acquisition unit; The relationship acquisition unit is used to obtain the terminal voltage steady-state value U of each power generation unit when the high voltage ride-through or low voltage ride-through is under the condition of full power generation of the new energy station. i ; The clustering algorithm is used to calculate the steady-state voltage value U of each generating unit. i Divide into multiple subclasses and obtain clustering results; According to the clustering results, the relative electrical topological relationship between each subclass is obtained; Perform impedance equalization on each subclass, and obtain the equivalent impedance of each subclass based on the principle that the power loss before and after equalization is equal; According to the equivalent impedance of each subclass and the relative electrical topological relationship between each subclass, the equivalent grid-connected impedance of the new energy station is obtained, and the relationship between the equivalent grid-connected impedance and the original network impedance is constructed; The grid-connected impedance acquisition unit is used to acquire the grid-connected impedance of the new energy station based on the electrical operation data and the relationship; According to the principle that the power loss before and after equalization is equal, the equivalent impedance of each subclass is obtained as follows: Among them, Z eq_k is the equivalent impedance of the kth class; the kth class corresponds to the original network containing K impedances, Z k_j is the jth impedance in the kth class, I k_j For flow through Z k_j The current I eq_k I is the total rated current of the generating units contained in the kth category, which can be determined according to the rated current values ​​of the generating units after classification; eq_k_in is the input current of the kth class.

5. According to the network structure-maintained new energy station grid-connected impedance equivalent acquisition system of claim 4, it is characterized in that: The clustering algorithm adopts K-means algorithm.

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