Power control stability discrimination method and device for grid-connected system of new energy station

Abstract

This invention discloses a method and apparatus for determining the power control stability of a renewable energy power plant grid-connected system. The method includes: establishing a Thevenin equivalent circuit based on electrical quantity information of the renewable energy power plant grid-connected system obtained from a typical structural diagram of the system; determining the grid connection point voltage formula, active power output expression, and reactive power output expression of the renewable energy power plant grid-connected system based on the power flow equations and KVL equations, and according to the Thevenin equivalent circuit; decomposing the grid connection point output current of the renewable energy power plant grid-connected system in the VSC rotating coordinate system to obtain the d-axis and q-axis current components of the output current, and substituting these components into the aforementioned expressions to determine the active power control stability criterion and reactive power control stability criterion of the renewable energy power plant grid-connected system; and determining the power control stability of the renewable energy power plant grid-connected system based on the active power control stability criterion and reactive power control stability criterion.

Description

Technical Field

[0001] This invention relates to the field of new energy grid-connected system technology, and more specifically, to a method and apparatus for determining the power control stability of a new energy power plant grid-connected system. Background Technology

[0002] With the continuous advancement of new power system construction, the trend of large-scale renewable energy grid connection is evident, and a large number of power electronic devices are widely used, resulting in significant changes to the operating characteristics of the power system. Timely assessment of the stability of renewable energy grid-connected systems can provide valuable reference for the planning of new power systems with renewable energy as the mainstay, and is of great significance for ensuring the safe and stable operation of the system and solving the problem of limited transmission capacity of renewable energy weak grids.

[0003] New energy power generation units use voltage source converters (VSCs) as their grid connection interface. Their control system mainly consists of three parts: a power outer loop, a current inner loop, and a phase-locked loop (PLL). The VSC outer loop control structure essentially controls the dq-axis current reference value. Since the VSC inner loop control speed is much faster than the outer loop, it can be reasonably assumed that the inner loop current output value is always consistent with the current reference value. Furthermore, when the system is in steady state, the PLL can be considered to be operating in an ideal state. Therefore, under conditions of strong grid support, the grid connection point voltage is approximately constant, and the active and reactive power outputs of the new energy power plant are proportional to the d-axis and q-axis currents, respectively, in the rotating coordinate system, achieving the goal of decoupling active and reactive power control. However, when grid support is weak, the power output of the new energy power plant affects each other through the grid connection point voltage. The coupling between active power and q-axis current, reactive power, and d-axis current deepens, causing the original control target to deviate, disrupting the coordination of the outer loop control, and ultimately leading to instability of the new energy grid-connected system. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and apparatus for determining the power control stability of a new energy power plant grid-connected system.

[0005] According to one aspect of the present invention, a method for determining the power control stability of a new energy power plant grid-connected system is provided, comprising:

[0006] By using the typical structural diagram of the grid-connected system of the new energy power station, the electrical quantity information of the grid-connected system of the new energy power station is obtained, and the Thevenin equivalent circuit is established based on the electrical quantity information.

[0007] Based on the power flow equations and KVL equations of the power system, and according to the Thevenin equivalent circuit, the grid connection point voltage formula, active power output expression and reactive power output expression of the grid-connected system of the new energy power station are determined.

[0008] The grid connection point output current of the new energy power station grid connection system is decomposed in the VSC rotating coordinate system to obtain the d-axis current component and q-axis current component of the grid connection point output current.

[0009] Substitute the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression and the reactive power output expression to determine the active power control stability criterion and the reactive power control stability criterion of the grid connection system of the new energy power station.

[0010] The power control stability of the grid-connected system of new energy power plants is determined based on the active power control stability criteria and the reactive power control stability criteria.

[0011] Optionally, the operation of substituting the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression, and the reactive power output expression to determine the active power control stability criterion and the reactive power control stability criterion of the new energy power plant grid-connected system includes:

[0012] Substitute the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression, and the reactive power output expression to determine the active power relationship and reactive power relationship related to the d-axis current component and the q-axis current component.

[0013] Based on the active power relationship and the reactive power relationship, the active power control stability criteria and the reactive power control stability criteria of the grid-connected system of new energy power plants are determined.

[0014] Optionally, based on the active power relationship and the reactive power relationship, the operation of constructing the active power control stability criterion and the reactive power control stability criterion of the new energy power plant grid-connected system includes:

[0015] Linearize the active power relationship and reactive power relationship by taking the d-axis current component and q-axis current component as independent variables, and determine the active power equation and reactive power equation with the small signal of the d-axis current component and the small signal of the q-axis current component.

[0016] Extract the coefficients of the small-signal d-axis current component and the small-signal q-axis current component from the active power equation and the reactive power equation to determine the active power control stability criterion and the reactive power control stability criterion.

[0017] Optionally, the operation of determining the stability of the renewable energy power plant grid-connected system based on the active power control stability criterion and the reactive power control stability criterion includes:

[0018] When R P and R Q When the value exceeds the first threshold, the power control stability of the grid-connected system of the new energy power station is at risk.

[0019] When R P and R Q When the power control of the grid-connected system of the new energy power station is less than the first threshold and greater than the second threshold, there is a risk of instability.

[0020] When R P and R Q When the value is less than the second threshold, the power control of the new energy power station grid-connected system remains stable, where R P As the active control stability criterion, R Q This serves as a criterion for reactive power control stability.

[0021] According to another aspect of the present invention, a power control stability discrimination device for a new energy power station grid-connected system is provided, comprising:

[0022] A module is established to obtain electrical quantity information of the grid-connected system of a new energy power station through a typical structural diagram of the grid-connected system, and to establish the Thevenin equivalent circuit based on the electrical quantity information.

[0023] The first determining module is used to determine the grid connection point voltage formula, active power output expression and reactive power output expression of the new energy power station grid connection system based on the power flow equation and KVL equation and according to the Thevenin equivalent circuit.

[0024] The decomposition module is used to decompose the grid connection point output current of the new energy power station grid connection system in the VSC rotating coordinate system to obtain the d-axis current component and q-axis current component of the grid connection point output current.

[0025] The second determining module is used to substitute the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression and the reactive power output expression to determine the active power control stability criterion and the reactive power control stability criterion of the grid connection system of the new energy power station.

[0026] The third determination module is used to determine the power control stability of the grid-connected system of the new energy power station based on the active power control stability criterion and the reactive power control stability criterion.

[0027] According to another aspect of the present invention, a computer-readable storage medium is provided, the storage medium storing a computer program for performing the methods described in any of the above aspects of the present invention.

[0028] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising: a processor; a memory for storing executable instructions of the processor; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the method described in any of the preceding aspects of the present invention.

[0029] Therefore, based on the Thevenin equivalent circuit of a renewable energy power plant grid-connected system, this application derives the mathematical relationships between key electrical quantities and performs sensitivity analysis on output power and dq-axis current. By comparing the relative magnitudes of these sensitivities, a novel method for determining the stability of power control in renewable energy grid-connected systems is proposed. Addressing the issue of increased coupling between active and reactive power outputs under weak grid conditions, the method calculates the magnitudes of output power and dq-axis current sensitivity to determine whether the control system can achieve its original control objectives. This method is used to assess the stability of power control in renewable energy grid-connected systems. Attached Figure Description

[0030] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0031] Figure 1 This is a flowchart illustrating a power control stability determination method for a new energy power station grid-connected system provided in an exemplary embodiment of the present invention.

[0032] Figure 2 This is another flowchart illustrating the power control stability determination method for a new energy power station grid-connected system provided in an exemplary embodiment of the present invention;

[0033] Figure 3 This is a typical structural diagram of a new energy grid-connected system provided by an exemplary embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the Thevenin equivalent circuit of a new energy grid-connected system provided in an exemplary embodiment of the present invention;

[0035] Figure 5 This is an exemplary embodiment of the present invention. P R Q A schematic diagram of the amplitude curves at different operating points;

[0036] Figure 6 This is a schematic diagram of the power control stability discrimination device for a new energy power station grid connection system provided in an exemplary embodiment of the present invention;

[0037] Figure 7 This is the structure of an electronic device provided in an exemplary embodiment of the present invention. Detailed Implementation

[0038] Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0039] It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0040] Those skilled in the art will understand that the terms "first," "second," etc., in the embodiments of the present invention are only used to distinguish different steps, devices, or modules, and do not represent any specific technical meaning, nor do they indicate a necessary logical order between them.

[0041] It should also be understood that in the embodiments of the present invention, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0042] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more unless explicitly defined or given contrary instructions in the context.

[0043] Furthermore, the term "and / or" in this invention is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this invention generally indicates that the preceding and following related objects have an "or" relationship.

[0044] It should also be understood that the description of the various embodiments in this invention emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0045] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0046] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0047] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0048] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0049] The embodiments of this invention can be applied to electronic devices such as terminal devices, computer systems, and servers, and can operate together with a wide range of other general-purpose or special-purpose computing system environments or configurations. Well-known examples of terminal devices, computing systems, environments, and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, and servers include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputer systems, mainframe computer systems, and distributed cloud computing environments including any of the above systems, etc.

[0050] Electronic devices such as terminal devices, computer systems, and servers can be described in the general context of computer system executable instructions (such as program modules) executed by a computer system. Typically, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in distributed cloud computing environments, where tasks are executed by remote processing devices linked through communication networks. In distributed cloud computing environments, program modules can reside on local or remote computing system storage media, including storage devices.

[0051] Exemplary methods

[0052] Figure 1 This is a flowchart illustrating a power control stability determination method for a new energy power station grid-connected system, provided in an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as... Figure 1 As shown, the power control stability judgment method 100 for a new energy power station grid-connected system includes the following steps:

[0053] Step 101: Obtain the electrical quantity information of the new energy power station grid connection system through the typical structural diagram of the new energy power station grid connection system, and establish the Thevenin equivalent circuit based on the electrical quantity information.

[0054] Step 102: Based on the power flow equations and KVL equations of the power system, and according to the Thevenin equivalent circuit, determine the grid connection point voltage formula, active power output expression and reactive power output expression of the grid-connected system of the new energy power station.

[0055] Step 103: Decompose the grid connection point output current of the new energy power station grid connection system in the VSC rotating coordinate system to obtain the d-axis current component and q-axis current component of the grid connection point output current.

[0056] Step 104: Substitute the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression, and the reactive power output expression to determine the active power control stability criterion and the reactive power control stability criterion of the new energy power station grid connection system.

[0057] Step 105: Determine the power control stability of the new energy power plant grid-connected system based on the active power control stability criterion and the reactive power control stability criterion.

[0058] Optionally, the operation of substituting the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression, and the reactive power output expression to determine the active power control stability criterion and the reactive power control stability criterion of the new energy power plant grid-connected system includes:

[0059] Substitute the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression, and the reactive power output expression to determine the active power relationship and reactive power relationship related to the d-axis current component and the q-axis current component.

[0060] Based on the active power relationship and the reactive power relationship, the active power control stability criteria and the reactive power control stability criteria of the grid-connected system of new energy power plants are determined.

[0061] Optionally, based on the active power relationship and the reactive power relationship, the operation of constructing the active power control stability criterion and the reactive power control stability criterion of the new energy power plant grid-connected system includes:

[0062] Linearize the active power relationship and reactive power relationship by taking the d-axis current component and q-axis current component as independent variables, and determine the active power equation and reactive power equation with the small signal of the d-axis current component and the small signal of the q-axis current component.

[0063] Extract the coefficients of the small-signal d-axis current component and the small-signal q-axis current component from the active power equation and the reactive power equation to determine the active power control stability criterion and the reactive power control stability criterion.

[0064] Optionally, the operation of determining the stability of the renewable energy power plant grid-connected system based on the active power control stability criterion and the reactive power control stability criterion includes:

[0065] When R P and R Q When the value exceeds the first threshold, the power control stability of the grid-connected system of the new energy power station is at risk.

[0066] When R P and R QWhen the power control of the grid-connected system of the new energy power station is less than the first threshold and greater than the second threshold, there is a risk of instability.

[0067] When R P and R Q When the value is less than the second threshold, the power control of the new energy power station grid-connected system remains stable, where R P As the active control stability criterion, R Q This serves as a criterion for reactive power control stability.

[0068] Specifically, such as Figure 1 and Figure 2 As shown, the method includes the following steps:

[0069] A. Through analysis of the appendix Figure 3 A typical grid-connected structure diagram of China's new energy sources is provided. Relevant electrical quantities are obtained, and its Thevenin equivalent circuit is established, as shown in the attached diagram. Figure 4 As shown;

[0070] B. Based on the appendix Figure 4 Ignoring line resistance, calculate the output expressions for grid connection point voltage, active power, and reactive power;

[0071] C. Assuming that the VSC phase-locked loop accurately tracks the grid connection point voltage, express the output current in the form of dq components in the VSC rotating coordinate system and substitute it into the expression in B.

[0072] D. Perform sensitivity analysis on the d-axis current and q-axis current using the expression in C, respectively, and establish a power control stability discrimination index R. P and R Q When R P and R Q If the value exceeds the first threshold (the first threshold can be, but is not limited to, 10), it is considered that the original control target of VSC has deviated, and the independent control of active and reactive power cannot be achieved, and the stability of the grid-connected system of the new energy power station is at risk.

[0073] In step A, by analyzing the appendix Figure 1 The grid connection structure diagram of China's new energy sources is attached. Relevant electrical quantities are obtained, and its Thevenin equivalent circuit is established. Figure 4 As shown, it mainly includes: monitoring the voltage at the grid connection point and the amplitude of the AC grid voltage, the phase of the phase-locked loop output, and the active and reactive power output at the grid connection point;

[0074] In step B, based on the attached Figure 4 Ignoring line resistance, the expressions for calculating the grid connection point voltage, active power, and reactive power output mainly include:

[0075] (1) When the grid-connected system of the new energy power station is in a stable operating state, based on the power flow equation and KVL equation, the expressions for its grid connection point voltage and power output are as shown in equations (1)-(3):

[0076]

[0077]

[0078]

[0079] In the formula, U t U s These are the grid connection point voltage and the AC grid voltage, respectively; I s θ is the output current at the grid connection point; θ is the phase of the phase-locked loop output; X s The line reactance is P; P and Q represent the output active power and reactive power, respectively.

[0080] In step C, assuming the VSC phase-locked loop accurately tracks the grid connection point voltage, the output current is expressed in the form of dq components in the VSC rotating coordinate system. Substituting this into the expression in B, the main components include:

[0081] (1) By decomposing the grid-connected output current in the VSC rotating coordinate system, the magnitude of the current under the quadrature and direct axes can be obtained, and the corresponding expression is shown in equation (4):

[0082]

[0083] In the formula, i sd i sq These are the d-axis and q-axis components of the output current at the grid connection point, respectively.

[0084] (2) Substituting equation (4) into equation (1), we can obtain the relationship between voltage Ut and isd and isq:

[0085] U t ∠θ=U s +jX s (i sd +ji sq )e jθ (5)

[0086] (3) Substituting the current and voltage expressions from equations (4) and (5) into the active and reactive expressions from equations (2) and (3), we can obtain the relationship between active and reactive power and the dq-axis current:

[0087]

[0088]

[0089] In step D, the expression in C is used to perform sensitivity analysis on the d-axis current and q-axis current respectively, and a power control stability discrimination index R is established. P and R QWhen R P and R Q A value greater than 10 indicates a deviation from the original control objective of VSC, making independent control of active and reactive power impossible. This poses a risk to the stability of the renewable energy power plant grid connection system, primarily including:

[0090] (1) In equations (6) and (7), P and Q are respectively represented by i sd i sq Taking the partial derivatives for the independent variable, we can obtain...

[0091]

[0092]

[0093] In the formula:

[0094] (2) Based on equations (8) and (9), the active power control stability criterion R of new energy power plants can be constructed. P Reactive power control stability criterion R Q :

[0095]

[0096]

[0097] (3) When R P and R Q When R is greater than 10, it can be considered that the original control target of the grid-connected converter of the new energy power station has deviated, and independent control of active and reactive power cannot be achieved, posing a risk to the power control stability of the grid-connected system of the new energy power station; when R P and R Q When the values ​​are less than 10 and greater than 0.1 (i.e., the second threshold can be, but is not limited to, 0.1), it can be considered that the power output of the grid-connected converter in the new energy power station is simultaneously affected by the dq-axis current, and the system power control has an instability risk; when RP and RQ are less than 0.1, it can be considered that the power output of the grid-connected converter in the new energy power station is dominated by the original control target, and the power control remains stable. Figure 5 As shown, R P R Q Amplitude curves at different operating points.

[0098] Therefore, based on the Thevenin equivalent circuit of a renewable energy power plant grid-connected system, this application derives the mathematical relationships between key electrical quantities and performs sensitivity analysis on output power and dq-axis current. By comparing the relative magnitudes of these sensitivities, a novel method for determining the stability of power control in renewable energy grid-connected systems is proposed. Addressing the issue of increased coupling between active and reactive power outputs under weak grid conditions, the method calculates the magnitudes of output power and dq-axis current sensitivity to determine whether the control system can achieve its original control objectives. This method is used to assess the stability of power control in renewable energy grid-connected systems.

[0099] Exemplary device

[0100] Figure 6 This is a schematic diagram of the power control stability discrimination device for a new energy power station grid-connected system provided in an exemplary embodiment of the present invention. Figure 6 As shown, the device 600 includes:

[0101] Module 610 is established to obtain electrical quantity information of the new energy power station grid connection system through the typical structural diagram of the new energy power station grid connection system, and to establish the Thevenin equivalent circuit based on the electrical quantity information.

[0102] The first determining module 620 is used to determine the grid connection point voltage formula, active power output expression and reactive power output expression of the new energy power station grid connection system based on the power flow equation and KVL equation and according to the Thevenin equivalent circuit.

[0103] The decomposition module 630 is used to decompose the grid connection point output current of the new energy power station grid connection system in the VSC rotating coordinate system to obtain the d-axis current component and q-axis current component of the grid connection point output current.

[0104] The second determining module 640 is used to substitute the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression and the reactive power output expression to determine the active power control stability criterion and the reactive power control stability criterion of the grid connection system of the new energy power station.

[0105] The third determining module 650 is used to determine the power control stability of the grid-connected system of the new energy power station based on the active power control stability criterion and the reactive power control stability criterion.

[0106] Optionally, the second determining module 640 includes:

[0107] The first determining submodule is used to substitute the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression and the reactive power output expression to determine the active power relationship and reactive power relationship related to the d-axis current component and the q-axis current component.

[0108] The second determination submodule is used to determine the active power control stability criteria and the reactive power control stability criteria of the grid-connected system of the new energy power station based on the active power relationship and the reactive power relationship.

[0109] Optionally, the second determining submodule includes:

[0110] The first determining unit is used to linearize the active power relationship and the reactive power relationship by taking the d-axis current component and the q-axis current component as independent variables, and to determine the active power equation and the reactive power equation with the small signal of the d-axis current component and the small signal of the q-axis current component.

[0111] The second determining unit is used to extract the coefficients of the small signals of the d-axis current component and the small signal of the q-axis current component in the active power equation and the reactive power equation, and to determine the active power control stability criterion and the reactive power control stability criterion.

[0112] Optionally, the third determining module 650 includes:

[0113] The first decision submodule is used when R... P and R Q When the value exceeds the first threshold, the power control stability of the grid-connected system of the new energy power station is at risk.

[0114] The second decision submodule is used when R P and R Q When the power control of the grid-connected system of the new energy power station is less than the first threshold and greater than the second threshold, there is a risk of instability.

[0115] The third decision submodule is used when R P and R Q When the value is less than the second threshold, the power control of the new energy power station grid-connected system remains stable, where R P As the active control stability criterion, R Q This serves as a criterion for reactive power control stability.

[0116] Exemplary electronic devices

[0117] Figure 7 This is the structure of an electronic device provided in an exemplary embodiment of the present invention. For example... Figure 7 As shown, the electronic device 70 includes one or more processors 71 and a memory 72.

[0118] The processor 71 may be a central processing unit (CPU) or other form of processing unit with data processing and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0119] The memory 72 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 71 may execute the program instructions to implement the methods of the software programs in the various embodiments of the present invention described above, and / or other desired functions. In one example, the electronic device may further include an input device 73 and an output device 74, these components being interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0120] In addition, the input device 73 may also include, for example, a keyboard, a mouse, etc.

[0121] The output device 74 can output various information to the outside. The output device 74 may include, for example, a display, a speaker, a printer, and a communication network and its connected remote output devices, etc.

[0122] Of course, for the sake of simplicity, Figure 7 Only some of the components of the electronic device relevant to the present invention are shown, omitting components such as buses, input / output interfaces, etc. In addition, the electronic device may include any other suitable components depending on the specific application.

[0123] Exemplary computer program products and computer-readable storage media

[0124] In addition to the methods and apparatus described above, embodiments of the present invention may also be computer program products, which include computer program instructions that, when executed by a processor, cause the processor to perform the steps in the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0125] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of the present invention. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0126] Furthermore, embodiments of the present invention may also be computer-readable storage media storing computer program instructions thereon, which, when executed by a processor, cause the processor to perform the steps of the methods for information mining of historical change records according to various embodiments of the present invention as described in the "Exemplary Methods" section above.

[0127] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.

[0128] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0129] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0130] The block diagrams of devices, systems, devices, and systems involved in this invention are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, systems, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0131] The methods and systems of the present invention may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of the present invention are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, the present invention may also be implemented as a program recorded on a recording medium, the program comprising machine-readable instructions for implementing the methods according to the present invention. Thus, the present invention also covers recording media storing programs for performing the methods according to the present invention.

[0132] It should also be noted that in the systems, apparatus, and methods of the present invention, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered equivalents of the present invention. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the invention. Therefore, the invention is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0133] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A method for determining the power control stability of a new energy power plant grid-connected system, characterized in that, include: By using a typical structural diagram of a new energy power station grid connection system, electrical quantity information of the new energy power station grid connection system is obtained, and a Thevenin equivalent circuit is established based on the electrical quantity information. Based on the power flow equations and KVL equations of the power system, and according to the Thevenin equivalent circuit, the grid connection point voltage formula, active power output expression and reactive power output expression of the new energy power station grid connection system are determined. The grid-connection point output current of the new energy power station grid-connection system is decomposed in the VSC rotating coordinate system to obtain the d-axis current component of the grid-connection point output current. i sd and q-axis current component i sq ; Substitute the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression, and the reactive power output expression to determine the active power control stability criterion and the reactive power control stability criterion of the new energy power station grid connection system. The power control stability of the new energy power station grid-connected system is determined based on the active power control stability criterion and the reactive power control stability criterion. The operation of substituting the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression, and the reactive power output expression to determine the active power control stability criterion and reactive power control stability criterion of the new energy power station grid connection system includes: Substitute the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression, and the reactive power output expression to determine the active power and reactive power relationships related to the d-axis current component and the q-axis current component. The active power relationship is shown in Equation (6) and the reactive power relationship is shown in Equation (7): （6） （7） In the formula, P Active power Q Reactive power U s AC mains voltage; X s For the reactance of the transmission line; In formulas (6) and (7), P , Q respectively i sd , i sq Taking the partial derivatives for the independent variable, we get: （8） （9） In the formula: intermediate variables ; Based on formulas (8) and (9), a criterion for active power control stability of new energy power plants is constructed. R P Reactive power control stability criterion R Q : （10） （11） The operation of determining the stability of the renewable energy power plant grid-connected system based on the active power control stability criterion and the reactive power control stability criterion includes: when R P and R Q When the value exceeds the first threshold, the power control stability of the new energy power station grid-connected system is at risk. when R P and R Q When the power is less than the first threshold and greater than the second threshold, the power control of the new energy power station grid connection system is at risk of instability. when R P and R Q When the power is less than the second threshold, the power control of the new energy power station grid-connected system remains stable, wherein R P As a criterion for effective control and stability, R Q This serves as a criterion for reactive power control stability.

2. A power control stability discrimination device for a new energy power station grid-connected system, used to implement the method described in claim 1, characterized in that, include: A module is established to obtain the electrical quantity information of the new energy power station grid connection system through a typical structural diagram of the new energy power station grid connection system, and to establish the Thevenin equivalent circuit based on the electrical quantity information. The first determining module is used to determine the grid connection point voltage formula, active power output expression, and reactive power output expression of the new energy power station grid connection system based on the power flow equation and KVL equation, and according to the Thevenin equivalent circuit. The decomposition module is used to decompose the grid connection point output current of the new energy power station grid connection system in the VSC rotating coordinate system to obtain the d-axis current component and q-axis current component of the grid connection point output current. The second determining module is used to substitute the d-axis current component and the q-axis current component into the grid connection point voltage formula, the active power output expression and the reactive power output expression to determine the active power control stability criterion and the reactive power control stability criterion of the new energy power station grid connection system. The third determining module is used to determine the power control stability of the new energy power station grid-connected system based on the active power control stability criterion and the reactive power control stability criterion.

3. A computer-readable storage medium, characterized in that, The storage medium stores a computer program for executing the method described in claim 1.

4. An electronic device, characterized in that, The electronic device includes: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method of claim 1.

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