Methods, devices, equipment and media for quantifying the power acceptance boundary of AC / DC systems

Abstract

This invention relates to the field of power system stability analysis technology, and particularly to a method, apparatus, device, and medium for quantifying the power acceptance boundary of AC / DC systems. The method includes: decomposing and reconstructing the power voltage sensitivity to obtain the equivalent admittance and equivalent power of the external characteristics; constructing a similarity transformation matrix to equivalently transform the system power flow Jacobian matrix into an improved complex Jacobian matrix; using singularity equivalence and Schur transform to reduce the order of the complex Jacobian matrix to construct the admittance ratio matrix, thus obtaining the system's limiting power boundary; estimating the power boundary based on matrix operator norm theory; and determining the critical state of the system approaching its power acceptance limit based on the admittance ratio index. This method comprehensively considers the impact of different control modes of DC and new energy equipment on the power acceptance limit, provides quantitative evaluation indicators, effectively determines whether the system is in a dangerous state or has reached its power acceptance limit, provides intuitive evaluation results, and is highly adaptable, helping to determine whether the system is operating safely and stably and making reasonable decisions.

Description

Technical Field

[0001] This invention relates to the field of power system stability analysis technology, and in particular to a method, apparatus, equipment and medium for quantifying the power acceptance boundary of AC / DC systems. Background Technology

[0002] In recent years, with the rapid development of high-voltage direct current (HVDC) transmission technology and the widespread application of renewable energy sources (such as wind and solar power), the structure and operating characteristics of power systems have undergone profound changes. In particular, with the large-scale application of HVDC projects and the rapid increase in installed capacity of new energy power generation, power systems have not only become more complex but also exhibit more diversified operating characteristics. While this transformation has greatly promoted the optimization of the energy structure and the green and low-carbon transition, it has also brought many challenges, especially system stability issues, thus placing higher demands on the assessment of power acceptance limits.

[0003] In traditional power system analysis, the system's power capacity limits are typically categorized into static power limits, dynamic power limits, and transient power limits. Static power limit analysis is one of the most common methods. Generally, the assessment of static power limits relies on power flow calculation models and the study of their interactions. However, with the continuous development of DC transmission and renewable energy generation, existing analytical models and methods are no longer sufficient to comprehensively and accurately describe the changes in the system's static power limits. In particular, the variable control modes and complex interactions between DC transmission and renewable energy equipment and AC systems further obscure the system's power capacity boundaries.

[0004] While the Jacobian matrix is ​​an important tool for analyzing the static stability of a system and can effectively quantify the power acceptance limit of a system, its calculation is complex. In particular, when dealing with the nonlinear characteristics brought about by DC systems and new energy equipment, the calculation of indicators such as the determinant and eigenvalues ​​of the Jacobian matrix is ​​difficult, making it difficult to assess in real time whether the system is approaching the power acceptance limit.

[0005] Therefore, quickly and effectively determining whether a power system is approaching its power acceptance limit and conducting timely risk assessments have become crucial for improving the static stability of power systems and ensuring their safe operation. Especially under complex operating conditions, the methods for assessing the power acceptance limit of a system urgently need improvement to better address the challenges posed by DC transmission and new energy equipment.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the general background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] This invention provides a method, apparatus, device, and medium for quantifying the power acceptance boundary of AC / DC systems, thereby effectively solving the problems in the background art.

[0008] To achieve the above objectives, the technical solution adopted by this invention is: a method for quantizing the power acceptance boundary of AC / DC systems, comprising the following steps:

[0009] The power voltage sensitivity of DC and new energy equipment under different control modes is decomposed and reconstructed to obtain the equivalent admittance and equivalent power of the external characteristics of each equipment.

[0010] Based on the equivalent admittance and equivalent power of the external characteristics, a similarity transformation matrix is ​​constructed, and the system power flow Jacobian matrix is ​​equivalently transformed to obtain the improved system complex Jacobian matrix.

[0011] The complex Jacobian matrix of the system is reduced in order by using singularity equivalence and Schur transform to construct the admittance ratio matrix, and the limiting power boundary conditions of the system are obtained based on the admittance ratio matrix.

[0012] Based on the matrix operator norm theory, the limiting power boundary is estimated, and the critical state when the system is close to the power acceptance limit is determined based on the preset improved admittance ratio index.

[0013] Furthermore, the model for the equivalent admittance of the external characteristic includes:

[0014] ;

[0015] In the formula, Represents the equivalent admittance phasor of external characteristics; Indicates the external characteristic equivalent conductance; The external characteristic equivalent susceptance is represented by j; j represents the imaginary unit. Indicates the node voltage amplitude. Indicates the phase angle of the node voltage; This indicates the active power emitted by the equipment; This indicates the reactive power emitted by the equipment.

[0016] Furthermore, the model for the equivalent power of the external characteristic includes:

[0017] ;

[0018] In the formula, Indicates the external characteristic equivalent power; This represents the equivalent active power of the external characteristics. Represents the external characteristic equivalent reactive power; j represents the imaginary unit; Indicates the node voltage amplitude. Indicates the phase angle of the node voltage; This indicates the active power emitted by the equipment; This indicates the reactive power emitted by the equipment.

[0019] Furthermore, the similarity transformation matrix includes:

[0020] ;

[0021] In the formula, Represents the similarity transformation matrix; Represents the node voltage phasor; represents the conjugate of the node voltage phasor; j represents the imaginary unit.

[0022] Furthermore, the complex Jacobian matrix of the system is represented by the following equivalent transformation:

[0023] ;

[0024] In the formula, Represents the complex Jacobian matrix of the improved system; Represents the system power flow Jacobian matrix; The Jacobian matrix on the AC side represents the characteristics of the AC network port. The Jacobian matrix on the device side represents the characteristics of the device ports. This represents a submatrix of the reduced-order system admittance matrix after removing the tie nodes. For systems without generator PV nodes, The submatrix obtained by removing the rows and columns related to the equilibrium nodes from the admittance matrix of the reduced-order system; This represents the equivalent admittance of the external characteristics; The matrix represents the similarity transformation matrix; j represents the imaginary unit. Indicates the magnitude of the node voltage; The conjugate of the complex power emitted by the device; Represents the conjugate of the equivalent power phasor of the external characteristic; The phasor exponent form representing the phase angle of the node voltage.

[0025] Furthermore, the complex Jacobian matrix of the system is reduced in order using singularity equivalence and Schur transform, including:

[0026] ;

[0027] In the formula, Represents the complex Jacobian matrix of the improved system; This represents a submatrix representing the reduced-order system admittance matrix after removing the connection nodes; This represents the equivalent admittance of the external characteristics; Represents the admittance ratio matrix; Indicates the magnitude of the node voltage; The conjugate of the complex power emitted by the device; Represents the conjugate of the equivalent power phasor of the external characteristic; The phasor exponent form representing the phase angle of the node voltage.

[0028] Furthermore, the admittance ratio matrix includes:

[0029] ;

[0030] ;

[0031] ;

[0032] In the formula, Represents the admittance ratio matrix; Indicates the magnitude of the node voltage; The conjugate of the complex power emitted by the device; Represents the conjugate of the equivalent power phasor of the external characteristic; The phasor exponent form representing the phase angle of the node voltage; This represents the conjugate of a submatrix of the reduced-order system admittance matrix after removing the connection nodes; It represents the conjugate of the equivalent admittance of the external characteristics.

[0033] Furthermore, the limiting power boundary conditions of the system are obtained based on the admittance ratio matrix, including:

[0034] when The system is operating stably and within the power acceptance boundary;

[0035] when The system reaches its power acceptance limit and becomes critically stable.

[0036] when The system became unstable and was outside the power acceptance boundary.

[0037] Furthermore, the improved admittance ratio includes:

[0038] ;

[0039] In the formula, A conservative criterion for evaluating the system's power acceptance limit; To provide an accurate criterion for assessing the power acceptance limit of a system; For the critical improved admittance ratio This represents the admittance ratio matrix.

[0040] Furthermore, based on a preset improved admittance ratio metric, the critical state at which the system approaches its power acceptance limit is determined, including:

[0041] according to The distance from 1 indicates the distance between the system's current power and its power acceptance limit;

[0042] when The system has not reached its power acceptance limit and remains in stable operation.

[0043] when The system is nearing its power acceptance limit and is in a hazardous operating area.

[0044] when If the system power continues to increase, then a judgment is made. Whether the predetermined threshold is met, accurately determine whether the system has reached its power acceptance limit.

[0045] The present invention also includes a power acceptance boundary quantization device for AC / DC systems, using the method described above, comprising:

[0046] The power voltage sensitivity decomposition and reconstruction unit is used to decompose and reconstruct the power voltage sensitivity of DC and new energy equipment under different control modes to obtain the equivalent admittance and equivalent power of the external characteristics of each equipment.

[0047] The similarity transformation matrix construction unit is used to construct a similarity transformation matrix based on the equivalent admittance and equivalent power of the external characteristics, and to equivalently transform the system power flow Jacobian matrix to obtain an improved system complex Jacobian matrix.

[0048] The order reduction processing unit is used to reduce the order of the complex Jacobian matrix of the system by using singularity equivalence and Schur transform to construct the admittance ratio matrix.

[0049] A power acceptance boundary calculation unit is used to obtain the limiting power boundary conditions of the system based on the admittance ratio matrix.

[0050] The power acceptance limit judgment unit is used to estimate the power limit boundary based on the matrix operator norm theory, and to judge the critical state when the system is close to the power acceptance limit based on the preset improved admittance ratio index.

[0051] The present invention also includes a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the method as described above.

[0052] The present invention also includes a storage medium having a computer program stored thereon, which, when executed by a processor, implements the method as described above.

[0053] The beneficial effects of this invention are as follows:

[0054] This evaluation method comprehensively considers the impact of different control modes of DC and new energy equipment on the system power acceptance limit, and provides quantitative evaluation indicators (improved admittance ratio, critical value). It can effectively determine whether the system is in a dangerous operating state or has reached the power acceptance limit, making the evaluation results more intuitive. The proposed indicators are not limited by equipment type and network topology, have good adaptability, and are conducive to judging whether the system can operate safely and stably, thereby making scientific and reasonable decisions. Attached Figure Description

[0055] 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 some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 A flowchart for a method to quantify the power acceptance boundary of an AC / DC system;

[0057] Figure 2 A flowchart illustrating the implementation of the power acceptance boundary quantization method for AC / DC systems;

[0058] Figure 3 Topology diagram of the improved IEEE 39-node system;

[0059] Figure 4 The graph shows the variation of the minimum eigenvalue of the system Jacobian matrix and the improved admittance ratio with the increase of system load power.

[0060] Figure 5 A graph showing the variation of the improved admittance ratio as system load power increases under different control modes for DC and new energy equipment.

[0061] Figure 6 A schematic diagram of the power acceptance boundary quantization device for AC / DC systems;

[0062] Figure 7 This is a schematic diagram of the structure of a computer device. Detailed Implementation

[0063] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0064] Example 1:

[0065] like Figure 1 , 2As shown: A method for quantizing the power acceptance boundary of an AC / DC system, comprising the following steps:

[0066] S10: Decompose and reconstruct the power voltage sensitivity of DC and new energy equipment under different control modes to obtain the equivalent admittance and equivalent power of each equipment.

[0067] S20: Based on the equivalent admittance and equivalent power of the external characteristics, construct a similarity transformation matrix and perform an equivalent transformation on the system power flow Jacobian matrix to obtain an improved system complex Jacobian matrix;

[0068] S30: The complex Jacobian matrix of the system is reduced in order by using singularity equivalence and Schur transform to construct the admittance ratio matrix, and the limiting power boundary conditions of the system are obtained based on the admittance ratio matrix.

[0069] S40: Based on the matrix operator norm theory, the limiting power boundary is estimated, and the critical state of the system approaching the power acceptance limit is determined based on the preset improved admittance ratio index.

[0070] Therefore, according to the embodiment of the present invention, the AC / DC system power acceptance boundary quantification method based on improved admittance ratio decomposes and reconstructs the power voltage sensitivity of DC and new energy equipment under different control modes into equivalent admittance and equivalent power of external characteristics. The system power flow Jacobian matrix is ​​reduced to equivalent order to construct the admittance ratio matrix, and the system limit power boundary condition based on the admittance ratio matrix is ​​obtained. By defining the improved admittance ratio index, the system can be quickly evaluated to determine whether it is close to the power acceptance limit. The method of the present invention can effectively evaluate the static power limit of AC / DC systems considering different control modes of equipment.

[0071] Compared with existing technologies, the significant advantages of the proposed method for quantifying the power acceptance limit of AC / DC systems based on improved admittance ratio are as follows: This evaluation method comprehensively considers the impact of different control modes of DC and new energy equipment on the system power acceptance limit, and provides quantitative evaluation indicators (improved admittance ratio, critical value). It can effectively determine whether the system is in a dangerous operating state or has reached the power acceptance limit, making the evaluation results more intuitive. The proposed indicators are not limited by equipment type and network topology, have good adaptability, and are conducive to judging whether the system can operate safely and stably, thereby making scientific and reasonable decisions.

[0072] This method provides more accurate system power limit boundary conditions through improved Jacobian matrices, order reduction techniques, and admittance ratio matrices. This means it can more accurately assess the power acceptance capability of AC / DC systems under different control modes, effectively predicting whether the system is approaching its power acceptance limit and avoiding system overload and instability. It comprehensively considers the power voltage sensitivity of DC and new energy equipment under different control modes, a more comprehensive and flexible approach than traditional methods. Applicable to various equipment configurations and control strategies, it has strong adaptability and can better address the impact of different system configurations on the power acceptance limit.

[0073] By performing an equivalent transformation of the system power flow Jacobian matrix and employing order reduction techniques (such as singularity equivalence and Shure transformation), the computational complexity of the system's power limit boundary is significantly reduced. This allows the method to quickly and effectively assess system stability in practical applications, avoiding the cumbersome computational processes of traditional methods. The method introduces an improved admittance ratio index and, through estimation based on matrix operator norm theory, enables rapid assessment of whether the system is approaching its power acceptance limit. In particular, the defined "improved admittance ratio index" allows for real-time monitoring of the system's operating status, timely detection of whether the system has entered a dangerous region, and provides rapid response decision support. Accurate assessment of the power acceptance limit and real-time monitoring effectively prevent system instability due to overload. This contributes to improving the safety and reliability of AC / DC systems, ensuring stable operation in complex operating environments, and reducing the risk of outages.

[0074] This method is not limited by equipment type, control mode, or network topology, and therefore can be widely applied to various power systems, including not only traditional AC grids but also modern AC / DC hybrid systems. Whether it's a high-voltage direct current (HVDC) transmission system or a complex grid structure integrating new energy sources, this method can be used for power acceptance boundary quantification analysis.

[0075] As a preferred embodiment of the above embodiments, in step S10, the model of the external characteristic equivalent admittance includes:

[0076] ;

[0077] In the formula, Represents the equivalent admittance phasor of external characteristics; Indicates the external characteristic equivalent conductance; The external characteristic equivalent susceptance is represented by j; j represents the imaginary unit. Indicates the node voltage amplitude. Indicates the phase angle of the node voltage; This indicates the active power emitted by the equipment; This indicates the reactive power emitted by the equipment; Indicates the active voltage phase angle sensitivity of the equipment; Indicates the reactive voltage phase angle sensitivity of the equipment; Indicates the sensitivity of the device to the active voltage amplitude; This indicates the sensitivity of the equipment to reactive voltage amplitude.

[0078] By introducing an external characteristic equivalent admittance model, the electrical characteristics and power acceptance behavior of the equipment can be simulated more accurately. In particular, considering the active and reactive phase angle sensitivity and voltage sensitivity of the equipment, a more accurate assessment of the power acceptance boundary of the system can be provided.

[0079] In this embodiment, in step S10, the model of the external characteristic equivalent power includes:

[0080] ;

[0081] In the formula, Indicates the external characteristic equivalent power; This represents the equivalent active power of the external characteristics. Represents the external characteristic equivalent reactive power; j represents the imaginary unit; Indicates the node voltage amplitude. Indicates the phase angle of the node voltage; This indicates the active power emitted by the equipment; This indicates the reactive power emitted by the equipment.

[0082] The aforementioned external characteristic equivalent admittance and equivalent power can be applied not only to DC and new energy equipment, but also to power supplies and loads with power voltage sensitivity.

[0083] By introducing an external characteristic equivalent power model, this method can accurately calculate the contribution of each device in an AC / DC system to the power acceptance limit, especially in complex systems (such as AC / DC hybrid systems with renewable energy grid connection). This helps to accurately estimate whether the system is approaching its power acceptance limit.

[0084] In step S20, the similarity transformation matrix includes:

[0085] ;

[0086] In the formula, Represents the similarity transformation matrix; Represents the node voltage phasor. ; represents the conjugate of the node voltage phasor; j represents the imaginary unit.

[0087] By introducing a similarity transformation matrix, this method can more accurately describe the relationships between node voltages in power systems, especially in complex AC / DC hybrid systems. The use of the similarity transformation matrix facilitates a more detailed analysis of device node voltages and power flow, thereby improving the accuracy of power acceptance boundary assessment.

[0088] As a preferred embodiment of the above, in step S20, the system complex Jacobian matrix is ​​represented by the following equivalent transformation:

[0089] ;

[0090] In the formula, Represents the complex Jacobian matrix of the improved system; Represents the system power flow Jacobian matrix; The Jacobian matrix on the AC side represents the characteristics of the AC network port. The Jacobian matrix on the device side represents the characteristics of the device ports. This represents a submatrix of the reduced-order system admittance matrix after removing the tie nodes. For systems without generator PV nodes, The submatrix obtained by removing the rows and columns related to the equilibrium nodes from the reduced-order system admittance matrix is ​​used for systems with generator PV nodes. The submatrix obtained by removing the rows and columns related to the equilibrium nodes and the rows and columns related to the generator PV nodes from the reduced-order system admittance matrix; This represents the equivalent admittance of the external characteristics; The matrix represents the similarity transformation matrix; j represents the imaginary unit. Indicates the magnitude of the node voltage; The conjugate of the complex power emitted by the device; Represents the conjugate of the equivalent power phasor of the external characteristic; The phasor exponent form representing the phase angle of the node voltage. ; , These represent the active and reactive voltage phase angle sensitivity matrices of AC network nodes, respectively. , These represent the active and reactive voltage amplitude sensitivity matrices of AC network nodes, respectively.

[0091] By using an improved system complex Jacobian matrix, the power acceptance limit of AC / DC systems can be evaluated more accurately. The introduction of similarity transformation, order reduction, and external characteristic admittance allows for the consideration of more details and device characteristics when calculating the power acceptance boundary, thus improving evaluation accuracy.

[0092] The use of similarity transformation matrices can reduce computational complexity when dealing with high-dimensional complex systems while maintaining the integrity of system characteristics. This is crucial for analyzing the stability of AC / DC systems, especially in systems with complex equipment and diverse control methods, enabling more accurate capture of the interactions between equipment and networks and improving the system's stability analysis capabilities.

[0093] In this embodiment, in step S30, the complex Jacobian matrix of the system is reduced in order using singularity equivalence and Schur transform, including:

[0094] ;

[0095] In the formula, Represents the complex Jacobian matrix of the improved system; This represents a submatrix representing the reduced-order system admittance matrix after removing the connection nodes; This represents the equivalent admittance of the external characteristics; Represents the admittance ratio matrix; Indicates the magnitude of the node voltage; The conjugate of the complex power emitted by the device; Represents the conjugate of the equivalent power phasor of the external characteristic; The phasor exponent form representing the phase angle of the node voltage. .

[0096] Using singularity equivalence and Shure transformation to reduce the order of the complex Jacobian matrix helps simplify the complexity of large-scale AC / DC power systems, preserves system characteristics, and ensures the accuracy of power acceptance boundary assessment. The reduced admittance matrix and improved complex Jacobian matrix enhance computational accuracy and avoid oversimplification and computational errors inherent in traditional methods.

[0097] In step S30, the admittance ratio matrix includes:

[0098] ;

[0099] ;

[0100] ;

[0101] In the formula, Represents the admittance ratio matrix; Indicates the magnitude of the node voltage; The conjugate of the complex power emitted by the device; Represents the conjugate of the equivalent power phasor of the external characteristic; The phasor exponent form representing the phase angle of the node voltage. ; This represents the conjugate of a submatrix of the reduced-order system admittance matrix after removing the connection nodes; It represents the conjugate of the equivalent admittance of the external characteristics.

[0102] This method, by introducing the admittance ratio matrix, can more accurately assess the power acceptance limit of AC / DC systems. In particular, by introducing parameters such as node voltage magnitude, conjugate of complex power, and conjugate of external characteristic equivalent power, it can more accurately capture the relationship between various devices and the system in the power system, avoiding the accuracy loss in traditional simplified methods.

[0103] As a preferred embodiment of the above, in step S30, obtaining the limiting power boundary condition of the system based on the admittance ratio matrix includes:

[0104] when The system is operating stably and within the power acceptance boundary;

[0105] when The system reaches its power acceptance limit and becomes critically stable.

[0106] when The system becomes unstable and falls outside the power acceptance boundary. The limiting power boundary condition of this system holds exactly for systems without generator PV nodes, and approximately for systems with generator PV nodes.

[0107] Based on the operator norm of the admittance ratio matrix, sufficient conditions for the system not to reach the power acceptance limit include:

[0108] ;

[0109] In the formula, , Let represent the minimum and maximum eigenvalues ​​of the matrix, respectively; Operator norms of matrices; This represents the admittance ratio matrix.

[0110] In this embodiment, in step S40, the improved admittance ratio index includes:

[0111] ;

[0112] In the formula, To improve the admittance ratio; A conservative criterion for evaluating the system's power acceptance limit; To provide an accurate criterion for assessing the power acceptance limit of a system; For the critical improved admittance ratio This represents the admittance ratio matrix.

[0113] Improved admittance ratio ( The metric provides the system with a more accurate tool for assessing power acceptance boundaries. By introducing... (Conservative criteria) and (Accurate Criteria) This method provides a more detailed assessment of power acceptance limits while maintaining system safety. Especially in complex AC / DC systems, this method avoids misjudgments or over-conservatism in traditional methods, thus improving the accuracy of the assessment.

[0114] As a preferred embodiment of the above, in step S40, determining the critical state of the system approaching its power acceptance limit based on a preset improved admittance ratio index includes:

[0115] according to The distance from 1 indicates the distance between the system's current power and its power acceptance limit;

[0116] when The system has not reached its power acceptance limit and remains in stable operation.

[0117] when The system is nearing its power acceptance limit and is in a hazardous operating area.

[0118] when If the system power continues to increase, then a judgment is made. Whether the predetermined threshold is met, accurately determine whether the system has reached its power acceptance limit.

[0119] This method can dynamically monitor the approach to the power acceptance limit as system power increases. When system power continues to increase and Approaching the critical value (e.g.) If the load is close to the power acceptance limit, timely control measures such as scheduling and load regulation can be taken to effectively avoid overload and system instability. The system uses conservative criteria ( ) and accurate criteria ( By progressively assessing power acceptance limits, the system is less likely to enter a dangerous state due to calculation or decision-making errors, thereby enhancing the safety of system operation.

[0120] Example 2:

[0121] Further integration Figures 3 to 5 As shown, based on the implementation of the evaluation method in the above embodiments, the implementation of the AC / DC system power acceptance boundary quantization method of the present invention is further explained.

[0122] like Figure 3The topology diagram of the improved IEEE 39-node system shown is an improvement over the original IEEE 39-node system, which is to change the generator at node 34 to be connected to the LCC DC system and the generator at node 37 to be connected to the new energy unit, while keeping the output power of both the generator and the original generator output power consistent.

[0123] First, the effectiveness of the improved admittance ratio index is verified by globally and synchronously increasing the power of all generators and loads. The changes in the minimum eigenvalue of the system Jacobian matrix and the improved admittance ratio index with the increase of system power are compared. The results are as follows: Figure 4 As shown.

[0124] It can be observed that the minimum eigenvalue of the system's Jacobian matrix changes very little with the increase of global power, only rapidly decreasing to a critical value near the static power limit. This trend makes it difficult to predict in advance whether the system is gradually approaching its power limit, and it is difficult to effectively assess whether the system has reached its power acceptance limit. However, for the improved admittance ratio (IAR1), it decreases significantly and monotonically with the increase of global power, remaining in an approximately linear state globally. This trend can intuitively indicate that the system's operating state is approaching its power limit. Furthermore, the improved admittance ratio crosses the critical value around a load factor of 1.3, differing from the actual power limit by only 10%. This shows that IAR1, as a conservative criterion for the system approaching its power acceptance limit, can effectively assess whether the system is approaching its power acceptance limit. After IAR1 crosses the critical value, IAR2 can be used to determine whether the system has reached its power acceptance limit. It can be seen that when the system reaches its power acceptance limit, IAR2 also reaches the critical value, indicating that IAR2, as an accurate criterion for the system reaching its power acceptance limit, can accurately assess whether the system has reached its power acceptance limit. Furthermore, some jumps in the improved admittance ratio index are caused by the generator PV node reactive power exceeding the limit and then switching to the PQ node.

[0125] The above verifies the effectiveness of the improved admittance ratio index. Further analysis examines the impact of different control modes for DC and renewable energy equipment on the system power acceptance limit. Similarly, the power of all generators and loads is globally and synchronously increased, and the changes in the improved admittance ratio index with system load power growth under different control modes for DC and renewable energy equipment are compared. The results are as follows: Figure 5 As shown, the initial control mode of the LCC DC system is CP-CEA (constant active power, constant arc extinction angle) mode, and the initial control mode of the new energy unit is constant power mode.

[0126] It can be found that the improved admittance ratio index is applicable to both DC and new energy equipment in different control modes, and can effectively assess whether the system has reached its power acceptance limit.

[0127] The present invention also includes a power acceptance boundary quantization device for AC / DC systems, such as... Figure 6As shown, the method described above includes:

[0128] The power voltage sensitivity decomposition and reconstruction unit is used to decompose and reconstruct the power voltage sensitivity of DC and new energy equipment under different control modes to obtain the equivalent admittance and equivalent power of the external characteristics of each equipment.

[0129] The similarity transformation matrix construction unit is used to construct a similarity transformation matrix based on the equivalent admittance and equivalent power of the external characteristics, and to equivalently transform the system power flow Jacobian matrix to obtain an improved system complex Jacobian matrix.

[0130] The order reduction processing unit is used to reduce the order of the complex Jacobian matrix of the system by using singularity equivalence and Schur transform to construct the admittance ratio matrix.

[0131] A power acceptance boundary calculation unit is used to obtain the limiting power boundary conditions of the system based on the admittance ratio matrix.

[0132] The power acceptance limit judgment unit is used to estimate the power limit boundary based on the matrix operator norm theory, and to judge the critical state when the system is close to the power acceptance limit based on the preset improved admittance ratio index.

[0133] See Figure 7 The diagram shows a structural schematic of a computer device provided in an embodiment of this application. An embodiment of this application provides a computer device 400, including a processor 410 and a memory 420. The memory 420 stores a computer program executable by the processor 410. When the computer program is executed by the processor 410, it performs the method described above.

[0134] This application embodiment also provides a storage medium 430, on which a computer program is stored, and the computer program is executed by a processor 410 to perform the above method.

[0135] The storage medium 430 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0136] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. "A plurality of" means two or more, unless otherwise explicitly specified.

[0137] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0138] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, 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.

[0139] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0140] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0141] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0142] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0143] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for quantifying the power acceptance boundary of an AC / DC system, characterized in that, Includes the following steps: The power voltage sensitivity of DC and new energy equipment under different control modes is decomposed and reconstructed to obtain the equivalent admittance and equivalent power of the external characteristics of each equipment. Based on the equivalent admittance and equivalent power of the external characteristics, a similarity transformation matrix is ​​constructed, and the system power flow Jacobian matrix is ​​equivalently transformed to obtain the improved system complex Jacobian matrix. The complex Jacobian matrix of the system is reduced in order by using singularity equivalence and Schur transform to construct the admittance ratio matrix, and the limiting power boundary conditions of the system are obtained based on the admittance ratio matrix. Based on the matrix operator norm theory, the limiting power boundary is estimated, and the critical state when the system approaches the power acceptance limit is determined based on the preset improved admittance ratio index. The improved admittance ratio includes: ； In the formula, A conservative criterion for evaluating the system's power acceptance limit; To provide an accurate criterion for assessing the power acceptance limit of a system; For the critical improved admittance ratio, Represents the admittance ratio matrix; For eigenvalues; The critical state at which the system approaches its power acceptance limit is determined based on a preset improved admittance ratio index, including: according to The distance from 1 indicates the distance between the system's current power and its power acceptance limit; when The system has not reached its power acceptance limit and remains in stable operation. when The system is nearing its power acceptance limit and is in a hazardous operating area. when If the system power continues to increase, then a judgment is made. Whether the predetermined threshold is met, accurately determine whether the system has reached its power acceptance limit; To improve the admittance ratio; A conservative criterion for evaluating the system's power acceptance limit.

2. The AC / DC system power acceptance boundary quantization method according to claim 1, characterized in that, The model of the equivalent admittance of the external characteristics includes: ； In the formula, Represents the equivalent admittance phasor of external characteristics; Indicates the external characteristic equivalent conductance; The external characteristic equivalent susceptance is represented by j; j represents the imaginary unit. Indicates the node voltage amplitude. Indicates the phase angle of the node voltage; This indicates the active power emitted by the equipment; This indicates the reactive power emitted by the equipment.

3. The AC / DC system power acceptance boundary quantization method according to claim 1, characterized in that, The model of the external characteristic equivalent power includes: ； In the formula, Indicates the external characteristic equivalent power; This represents the equivalent active power of the external characteristics. Represents the external characteristic equivalent reactive power; j represents the imaginary unit; Indicates the node voltage amplitude. Indicates the phase angle of the node voltage; This indicates the active power emitted by the equipment; This indicates the reactive power emitted by the equipment.

4. The AC / DC system power acceptance boundary quantization method according to claim 1, characterized in that, The similarity transformation matrix includes: ； In the formula, Represents the similarity transformation matrix; Represents the node voltage phasor; represents the conjugate of the node voltage phasor; j represents the imaginary unit.

5. The AC / DC system power acceptance boundary quantization method according to claim 2, characterized in that, The complex Jacobian matrix of the system is represented by the following equivalent transformation: ； In the formula, Represents the complex Jacobian matrix of the improved system; Represents the system power flow Jacobian matrix; The Jacobian matrix on the AC side represents the characteristics of the AC network port. The Jacobian matrix on the device side represents the characteristics of the device ports. This represents a submatrix of the reduced-order system admittance matrix after removing the tie nodes. For systems without generator PV nodes, The submatrix obtained by removing the rows and columns related to the equilibrium nodes from the admittance matrix of the reduced-order system; This represents the equivalent admittance of the external characteristics; The matrix represents the similarity transformation matrix; j represents the imaginary unit. Indicates the magnitude of the node voltage; The conjugate of the complex power emitted by the device; Represents the conjugate of the equivalent power phasor of the external characteristic; The phasor exponent form representing the phase angle of the node voltage.

6. The AC / DC system power acceptance boundary quantization method according to claim 1, characterized in that, The complex Jacobian matrix of the system is reduced in order using singularity equivalence and Schur transform, including: ； In the formula, Represents the complex Jacobian matrix of the improved system; This represents a submatrix representing the reduced-order system admittance matrix after removing the connection nodes; This represents the equivalent admittance of the external characteristics; Represents the admittance ratio matrix; Indicates the magnitude of the node voltage; The conjugate of the complex power emitted by the device; Represents the conjugate of the equivalent power phasor of the external characteristic; The phasor exponent form representing the phase angle of the node voltage.

7. The AC / DC system power acceptance boundary quantization method according to claim 1, characterized in that, The admittance ratio matrix includes: ； ； ； In the formula, Represents the admittance ratio matrix; Indicates the magnitude of the node voltage; The conjugate of the complex power emitted by the device; Represents the conjugate of the equivalent power phasor of the external characteristic; The phasor exponent form representing the phase angle of the node voltage; This represents the conjugate of a submatrix of the reduced-order system admittance matrix after removing the connection nodes; It represents the conjugate of the equivalent admittance of the external characteristics.

8. The AC / DC system power acceptance boundary quantization method according to claim 6, characterized in that, The limiting power boundary conditions of the system are obtained based on the admittance ratio matrix, including: when The system is operating stably and within the power acceptance boundary; when The system reaches its power acceptance limit and becomes critically stable. when The system became unstable and was outside the power acceptance boundary.

9. A power acceptance boundary quantization device for AC / DC systems, characterized in that, Using the method as described in any one of claims 1 to 8, comprising: The power voltage sensitivity decomposition and reconstruction unit is used to decompose and reconstruct the power voltage sensitivity of DC and new energy equipment under different control modes to obtain the equivalent admittance and equivalent power of the external characteristics of each equipment. The similarity transformation matrix construction unit is used to construct a similarity transformation matrix based on the equivalent admittance and equivalent power of the external characteristics, and to equivalently transform the system power flow Jacobian matrix to obtain an improved system complex Jacobian matrix. The order reduction processing unit is used to reduce the order of the complex Jacobian matrix of the system by using singularity equivalence and Schur transform to construct the admittance ratio matrix. A power acceptance boundary calculation unit is used to obtain the limiting power boundary conditions of the system based on the admittance ratio matrix. The power acceptance limit judgment unit is used to estimate the limit power boundary based on the matrix operator norm theory, and to judge the critical state when the system is close to the power acceptance limit based on the preset improved admittance ratio index.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1-8.

11. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1-8.

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