Sectional transmission capability evaluation method and system considering transient power angle stability constraint

Abstract

The disclosure provides a section power transmission capacity evaluation method and system considering transient power angle stability constraints, relating to the technical field of section power transmission capacity evaluation, comprising: based on the basic operation mode of the power grid, introducing a filtering condition based on the geographical-electric dual belonging relationship, constructing a three-dimensional comprehensive index, using the three-dimensional comprehensive index to screen and aggregate the power grid lines, and identifying the key power transmission section; taking the maximization of the transmission power of the key power transmission section as the target, and taking the transient power angle stability between the sending end power grid and the receiving end power grid as the core constraint, constructing a power transmission capacity evaluation optimization model; designing a decoupled fast stability discrimination criterion of "inter-provincial-intra-provincial", fusing parallel computing and variable step simulation mechanism, and based on the standby capacity redistribution and the operation mode of the new energy proportion keeping, automatically generating and adjusting the strategy to solve the power transmission capacity evaluation optimization model, and the disclosure finally can realize high-precision and high-efficiency evaluation and closed-loop improvement of the key section power transmission capacity.

Description

Technical Field

[0001] This disclosure relates to the field of cross-sectional power transmission capacity assessment technology, specifically to a cross-sectional power transmission capacity assessment method and system that considers transient power angle stability constraints. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] With the continuous expansion of cross-regional power grid interconnection, accurately assessing and improving the ultimate transmission power of key sections is one of the core requirements of power grid planning and dispatching departments. The transmission capacity of a section is constrained by a variety of factors, among which the transient power angle stability problem between the sending and receiving end units after a large disturbance is often a key bottleneck limiting the transmission capacity of a section.

[0004] Currently, the assessment methods for cross-sectional transmission capacity are mainly divided into two categories: one is the repetitive power flow method and the continuous power flow method based on static security constraints; the other is the time-domain simulation method based on time-domain simulation, which determines the limiting power by gradually increasing the cross-sectional transmission power and repeatedly performing time-domain simulations until the system becomes unstable. However, existing technical solutions still have the following limitations: (1) Existing time-domain simulation-based evaluation methods typically require monitoring the relative power angles between all generators in the entire network, resulting in a large computational load. Especially when analyzing inter-provincial transmission sections, the number of generators in the sending and receiving end grids is large, but the internal units often remain synchronized, and the actual instability mode is mainly manifested as the relative oscillation between the sending and receiving end groups. However, existing methods lack targeted simplification criteria, leading to a waste of computational resources and difficulty in embedding them into optimization models for explicit constraints; (2) The simulation computation is inefficient. It often requires dozens or even hundreds of full-time domain simulations, each of which uses a fixed small step size for integration, resulting in extremely long computation time. Although some studies use parallel computing technology to accelerate the process, the parallel granularity is relatively coarse, and it fails to achieve fine-grained acceleration from within a single simulation, resulting in limited overall efficiency improvement. (3) The generation and adjustment strategies for operating modes are too simplistic. Traditional methods typically adjust the output or load of all generators proportionally when changing the transmission power of a section, failing to consider the actual distribution of the reserve capacity of thermal power units. This results in operating modes that are not feasible in actual power grids or cannot be calculated through power flow calculations. Furthermore, existing studies on the impact of changes in the proportion of new energy sources on transmission capacity mostly adopt an enumeration approach of "changing scenarios and recalculating," lacking a systematic method for scenario generation and sensitivity analysis.

[0005] (4) The fault scenario configuration is not typical enough. In actual power grids, critical sections are often composed of multiple circuits, and there are often severe situations where one circuit fails after the N-1 maintenance and both circuits are disconnected at the same time. Existing assessment methods are not capable of automating the configuration of such typical severe faults, which leads to the assessment results being too optimistic.

[0006] (5) Lack of closed-loop over-limit adjustment strategy. Most methods stop at providing the limit transmission capacity. When the current operating power has exceeded the limit, there is a lack of specific and operable adjustment steps on how to quickly and smoothly reduce the cross-sectional power, which makes it difficult to provide dispatchers with direct auxiliary decision-making. Summary of the Invention

[0007] To address the aforementioned issues, this disclosure proposes a method and system for evaluating cross-sectional transmission capacity that considers transient power angle stability constraints. By constructing an optimization model with the goal of maximizing cross-sectional transmission power and constrained by the transient power angle difference between sending and receiving units, a fast stability discrimination criterion for "inter-province-intra-province" decoupling is designed. Parallel computing and variable step-size simulation technology are integrated, and an automatic generation and adjustment strategy for operating modes based on reserve capacity reallocation and maintaining the proportion of new energy sources is proposed. Ultimately, this achieves high-precision, high-efficiency evaluation and closed-loop improvement of key cross-sectional transmission capacity.

[0008] According to some embodiments, the present disclosure adopts the following technical solutions: A method for assessing the cross-sectional transmission capacity considering transient power angle stability constraints includes: Given a power grid topology, obtain the basic operating mode of the power grid; Based on the basic operation mode of the power grid, a filtering condition based on the dual regional-electrical affiliation relationship is introduced to construct a three-dimensional comprehensive index. The three-dimensional comprehensive index is used to screen and aggregate power grid lines and identify key transmission sections. With the goal of maximizing the transmission power of the key transmission sections, and with the transient power angle stability between the sending-end grid and the receiving-end grid as the core constraint, a transmission capacity assessment and optimization model is constructed. The design incorporates a fast and stable discrimination criterion for "inter-province-intra-province" decoupling, integrates parallel computing and variable step-size simulation mechanisms, and automatically generates and adjusts strategies based on the operation mode of reserve capacity redistribution and maintaining the proportion of new energy to solve the transmission capacity assessment optimization model. Ultimately, this achieves high-precision and high-efficiency assessment and closed-loop improvement of transmission capacity at key sections.

[0009] As one embodiment, based on the basic operation mode of the power grid, filtering conditions based on the dual regional-electrical affiliation relationship are introduced to construct a three-dimensional comprehensive index. This three-dimensional comprehensive index is then used to screen and aggregate power grid lines, identifying key transmission sections, including: By introducing filtering conditions based on the dual regional and electrical affiliation, the identified sections not only undertake important inter-provincial power transmission tasks electrically, but also clearly belong to specific sending and receiving provinces in terms of power grid zoning, thus avoiding misidentification of strong interconnected lines within the same province as key inter-provincial sections. A three-dimensional comprehensive index integrating electrical betweenness, power flow transfer factor and provincial affiliation conditions is constructed, and the line electrical betweenness and power flow transfer factor are calculated respectively; By constructing provincial attribution conditions and comprehensive vulnerability indicators and aggregating cross sections, key transmission sections are obtained.

[0010] As one embodiment, the method of constructing a transmission capacity assessment and optimization model with the goal of maximizing the transmission power of the key transmission section and the transient power angle stability between the sending-end and receiving-end power grids as the core constraint includes: Construct an objective function to maximize the active power transmission power of the target key transmission section; The transient power angle stability between the sending-end grid and the receiving-end grid is taken as the core constraint to ensure that, after the expected fault occurs, the maximum relative power angle difference between any generator in the sending-end grid and any generator in the receiving-end grid is less than the preset stability threshold. In addition to the core constraints, static safety constraints are constructed, including node power balance constraints, upper and lower limits of generator active power output, upper and lower limits of generator reactive power output, node voltage amplitude constraints, and line thermal stability limit constraints.

[0011] As one embodiment, the fast and stable discrimination criterion for "inter-province-intra-province" decoupling includes: The rapid stability discrimination criterion includes a two-level discrimination strategy. The first level uses isometry aggregation for rapid prediction. The second level performs detailed verification of all inter-provincial generator pairs for cases where the prediction result is stable, ignoring the relative sway of generators within each province. A stable threshold is set for the second-level discrimination process, and the power angle difference of all cross-regional pairs is calculated. If there exists any pair at any time... t If the power angle difference is greater than the stability threshold, the system is determined to be in transient power angle instability; otherwise, it is determined to be stable.

[0012] As one embodiment, the parallel computing and variable step size simulation mechanism integrates parallel acceleration and variable step size integration. In response to the characteristics of transient power angle stability assessment, which is drastic during the fault period and gradually decays after the fault, a step size dynamic adjustment strategy based on the maximum angular acceleration is designed to significantly reduce the number of integration steps while ensuring the accuracy of power angle simulation, thereby achieving synergistic acceleration in two dimensions. In terms of coarse-grained parallelism, the set of combinations of operating modes and fault locations to be evaluated is split into multiple independent subsets and distributed to multiple computing nodes for parallel execution; each node independently completes its assigned time-domain simulation task, and the overall computation time is determined by the slowest node. For fine-grained variable-step integration, the fourth-order Runge-Kutta method with variable step size is used for numerical integration within a single simulation task.

[0013] As one embodiment, the automatic generation and adjustment strategy for the operation mode based on reserve capacity reallocation and maintaining the proportion of new energy includes two parts: automatic generation of the operation mode for reserve capacity reallocation and generation of scenarios affecting different proportions of new energy. The automatic generation of the operation mode for reserve capacity reallocation includes: Set a power increment target; The output of thermal power units in the sending-end power grid is redistributed; If a unit exceeds the upper or lower limit after adjustment, the upper or lower limit will be taken and the excess or deficiency will be redistributed to other units. The scenarios generated by the impact of different proportions of new energy sources include: Set a target for the proportion of new energy sources; Adjust the output of new energy sources proportionally; Then the thermal power output will be redistributed; Finally, the relationship between power transmission capacity and the proportion of new energy sources is analyzed.

[0014] According to some embodiments, the present disclosure adopts the following technical solutions: A cross-sectional transmission capacity assessment system considering transient power angle stability constraints includes: The initialization module is used to obtain the basic operating mode of the power grid given the power grid topology; The critical section identification module is used to construct a three-dimensional comprehensive index based on the basic operation mode of the power grid, introduce filtering conditions based on the dual regional and electrical affiliation relationship, and use the three-dimensional comprehensive index to screen and aggregate power grid lines to identify critical transmission sections. The optimization model construction module is used to construct an optimization model for power transmission capacity assessment with the goal of maximizing the transmission power of the key transmission section and with the transient power angle stability between the sending-end grid and the receiving-end grid as the core constraint. The assessment and configuration enhancement module is used to design a fast and stable discrimination criterion for "inter-province-intra-province" decoupling. It integrates parallel computing and variable step size simulation mechanism, and automatically generates and adjusts strategies based on the operation mode of reserve capacity redistribution and maintaining the proportion of new energy to solve the transmission capacity assessment optimization model. Ultimately, it achieves high-precision and high-efficiency assessment and closed-loop enhancement of transmission capacity in key sections.

[0015] According to some embodiments, the present disclosure adopts the following technical solutions: A computer program product includes a computer program that, when executed by a processor, implements the cross-sectional transmission capacity assessment method considering transient power angle stability constraints.

[0016] According to some embodiments, the present disclosure adopts the following technical solutions: A non-transitory computer-readable storage medium is provided for storing computer instructions, which, when executed by a processor, implement the cross-sectional transmission capacity assessment method considering transient power angle stability constraints.

[0017] According to some embodiments, the present disclosure adopts the following technical solutions: An electronic device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to perform the method for evaluating cross-sectional transmission capacity considering transient power angle stability constraints.

[0018] Compared with the prior art, the beneficial effects of this disclosure are as follows: This disclosure presents a method for assessing the transmission capacity of power transmission sections considering transient power angle stability constraints. Addressing the unique characteristics of inter-provincial transmission sections, it proposes a three-dimensional comprehensive index integrating electrical betweenness, power flow transfer factor, and provincial affiliation conditions. This index filters and aggregates power grid lines, automatically identifying critical inter-provincial transmission sections. Compared to existing methods, this disclosure introduces a filtering condition based on a dual regional-electrical affiliation relationship into the comprehensive index. This ensures that the identified sections not only undertake important inter-provincial power transmission tasks electrically, but also clearly belong to a specific sending-end province and receiving-end province in terms of power grid zoning, thereby avoiding misidentification of strongly interconnected lines within the same province as critical inter-provincial sections.

[0019] This disclosure presents a method for assessing the cross-sectional transmission capacity considering transient power angle stability constraints. It proposes a hybrid acceleration strategy of "coarse-grained parallelism + fine-grained variable step size" specifically designed for transient power angle stability assessment scenarios. Existing research either employs parallel acceleration alone or variable step size integration alone. This disclosure organically integrates both methods and, considering the unique characteristics of transient power angle stability assessment—intense dynamics during faults and gradual decay after faults—designs a dynamic step size adjustment strategy based on maximum angular acceleration. This significantly reduces the number of integration steps while maintaining the accuracy of power angle simulation, achieving synergistic acceleration across both dimensions.

[0020] This disclosure presents a method for assessing the cross-sectional transmission capacity considering transient power angle stability constraints. Using a 2030 grid transmission capacity of 20041MW as a benchmark, when the actual power at a cross-section reaches 21080MW (exceeding the limit by approximately 5.2%), the output of the sending-end thermal power units is reduced according to the proportion of reserve capacity reduction. After two rounds of iterative adjustments, the cross-sectional power is reduced to 19950MW, meeting safety constraints. The adjustment process is smooth and power flow converges. This disclosure provides clear and quantifiable steps for handling exceeding limits. It has significant beneficial effects in terms of assessment accuracy, adaptability to new energy sources, mechanism disclosure, and practical adjustment, and can provide effective technical support for the planning, operation, and control of the sending and receiving end power grids. Attached Figure Description

[0021] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure.

[0022] Figure 1 This is a flowchart of a method for evaluating the cross-sectional transmission capacity considering transient power angle stability constraints according to an embodiment of this disclosure; Figure 2 A flowchart generated for the operation mode of the embodiments of this disclosure; Figure 3 The power response curve of the transmission channel under a stable scenario according to the embodiments of this disclosure; Figure 4 The power response curve of the transmission channel under the instability scenario of this disclosure embodiment is shown. Detailed Implementation

[0023] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0024] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] Example 1 One embodiment of this disclosure provides a method for evaluating the cross-sectional transmission capacity considering transient power angle stability constraints. The method includes the following steps: Step 1: Given the power grid topology, obtain the basic operating mode of the power grid; Step 2: Based on the basic operation mode of the power grid, introduce filtering conditions based on the dual regional-electrical affiliation relationship, construct a three-dimensional comprehensive index, and use the three-dimensional comprehensive index to screen and aggregate power grid lines to identify key transmission sections; Step 3: With the goal of maximizing the transmission power of the key transmission sections, and with the transient power angle stability between the sending-end grid and the receiving-end grid as the core constraint, construct a transmission capacity assessment and optimization model; Step 4: Design a fast and stable discrimination criterion for "inter-province-intra-province" decoupling, integrate parallel computing and variable step size simulation mechanism, and automatically generate and adjust strategies based on the operation mode of reserve capacity redistribution and maintaining the proportion of new energy to solve the transmission capacity assessment optimization model, so as to finally achieve high-precision and high-efficiency assessment and closed-loop improvement of transmission capacity of key sections.

[0027] As an example, this disclosure presents a method for assessing the cross-sectional transmission capacity considering transient power angle stability constraints. This addresses the problems of existing inter-provincial transmission cross-sectional limit transmission power assessment methods, such as difficulty in accurately considering transient power angle stability constraints, low simulation efficiency, a single operational mode generation strategy, lack of adaptability to changes in the proportion of renewable energy, and lack of closed-loop over-limit adjustment strategies. This disclosure proposes a method for assessing the cross-sectional transmission capacity considering transient power angle stability constraints. This method constructs an optimization model with the goal of maximizing cross-sectional transmission power and constrained by the transient power angle difference between the sending and receiving units. It designs a fast stability discrimination criterion for "inter-provincial-intra-provincial" decoupling, integrates parallel computing and variable step-size simulation technology, and proposes an automatic generation and adjustment strategy for operational modes based on reserve capacity reallocation and renewable energy ratio maintenance. Ultimately, it achieves high-precision, high-efficiency assessment and closed-loop improvement of the transmission capacity of key cross-sections. The specific implementation process is as follows: Step 1: Automatically identify and select key transmission sections.

[0028] The selection of key transmission sections is a prerequisite for assessing inter-provincial transmission capacity. Considering the unique characteristics of inter-provincial transmission sections, this disclosure proposes a three-dimensional comprehensive index integrating electrical betweenness, power flow transfer factor, and provincial affiliation conditions to screen and aggregate power grid lines, thereby automatically identifying key inter-provincial transmission sections. Compared with existing methods, this disclosure introduces a filtering condition based on a dual geographical-electrical affiliation relationship into the comprehensive index, ensuring that the identified sections not only undertake important inter-provincial power transmission tasks electrically, but also clearly belong to a specific sending-end province and receiving-end province in terms of power grid partitioning. This avoids misidentifying strongly connected lines within the same province as key inter-provincial transmission sections.

[0029] (1) Calculate the electrical betweenness of the line. For a given power grid topology, define the line... electrical dielectric for:

[0030] in, For the set of generator nodes, For the set of load nodes; , Generators and load The weight (can be taken as rated power); In the "generator-load" pair When a unit current is injected between the lines The current generated on; In the "generator-load" pair When a unit current is injected between the lines The current generated on; This represents the set of all lines. The electrical betweenness reflects the importance of a line in the overall power transmission of the network.

[0031] (2) Calculate the power flow transfer factor. For a anticipated fault such as the interruption of a certain line, calculate the power flow transfer factor on other lines. For each line... When the line After the interruption, its power flow transfer factor Defined as:

[0032] in, circuit in the ground state active power, For the line After the line is disconnected The active power.

[0033] (3) Construct provincial affiliation conditions and comprehensive vulnerability indicators, and perform cross-sectional aggregation. First, define the route. l Comprehensive vulnerability index:

[0034] in, For the adaptive weighting coefficient of power transmission direction between provinces, Let m be the electrical dielectric constant of line m. For inter-provincial transmission sections, when the power flow direction of the section is consistent with the main outward transmission direction, a larger value (0.65 in this disclosure) is used to highlight the contribution of the electrical dielectric constant; when the section is in an operation mode where the receiving end is mainly absorbed, a smaller value (0.55 in this disclosure) is used to increase the weight of the power flow transfer factor, thereby dynamically reflecting the importance of the section under different operating modes. A threshold is set. Filter out A set of lines. For any two lines in this set, if the electrical distance between them... ( If both lines simultaneously meet the provincial affiliation criteria (i.e., the two busbars belong to the sending and receiving provinces respectively), they are aggregated into the same inter-provincial key transmission section. This filtering step ensures that strong intra-provincial transmission lines are not mistakenly identified as critical inter-provincial sections, improving the targeting of section identification. The identified critical transmission sections will be the specific targets for subsequent evaluation.

[0035] Step 2: Construct an optimization model for power transmission capacity assessment that considers the transient power angle stability constraints between provinces.

[0036] This disclosure constructs an optimization model with the objective of maximizing the transmission power at the critical section and the transient power angle stability between the sending-end and receiving-end power grids as the core constraint.

[0037] Specifically, the objective function is to maximize the active power transmission at the target cross section. P :

[0038] in, This refers to the set of key transmission line sections to be evaluated. For the line The active power transmitted uplink.

[0039] Furthermore, the core constraint is the inter-provincial transient power angle stability constraint. This ensures that, after a anticipated fault occurs, the maximum relative power angle difference between any generator in the sending-end grid and any generator in the receiving-end grid is less than a preset stability threshold.

[0040] in, and These are the generator sets of the sending-end power grid and the receiving-end power grid, respectively. and For generator and generator exist The angle of attack at any moment; As a preset power angle stability threshold, this disclosure takes ; The time when the fault occurred. This is the end time of the simulation.

[0041] Furthermore, static safety constraints are constructed in addition to the core constraints. These static safety constraints include node power balance constraints, generator active power output upper and lower limit constraints, generator reactive power output upper and lower limit constraints, node voltage amplitude constraints, and line thermal stability limit constraints. Specifically: (1) Node power balance constraints (power flow equations):

[0042]

[0043] (2) Upper and lower limits of generator active power output constraints:

[0044] (3) Upper and lower limits of generator reactive power output constraints:

[0045] (4) Node voltage amplitude constraints:

[0046] (5) Line thermal stability limit constraints:

[0047] in, G This is the collection of all generators in the power grid. D For the set of all loads, N The set of all nodes. This refers to the set of key transmission line sections to be evaluated. , They are nodes i Voltage amplitude and phase angle; For nodes i and nodes j The voltage phase angle difference between them; , The first node in the admittance matrix is ​​the... i Line number j The conductivity and susceptance components of the column elements; , They are nodes i The active and reactive power output of the generator. , They are nodes i Active and reactive power under load; Generators i Minimum and maximum technical limits for active and passive power output; For generator i Minimum technical limit for reactive power output; For generator i The maximum technical limit for reactive power output; They are nodes i Permissible minimum and maximum voltage; For the line l Active power transmitted upstream; For the line The maximum active power that can be transmitted.

[0048] Step 3: Design a fast and stable discrimination criterion for "inter-province-intra-province" decoupling, integrate parallel computing and variable step size simulation mechanism, and automatically generate and adjust strategies based on the operation mode of reserve capacity redistribution and new energy ratio maintenance to solve the transmission capacity assessment optimization model, and finally achieve high-precision and high-efficiency assessment and closed-loop improvement of transmission capacity of key sections.

[0049] Step 31: To reduce the computational complexity of transient stability assessment while ensuring the accuracy of the discrimination results, this disclosure proposes a fast stability discrimination criterion of "inter-provincial-intra-provincial" decoupling. The fast stability discrimination criterion includes a two-level discrimination strategy: the first level uses isometry aggregation for rapid prediction, and the second level further verifies all inter-provincial generator pairs in detail for cases where the prediction result is stable, while ignoring the relative sway of generators within each province.

[0050] First, all generators in the sending-end power grid are weighted according to their moment of inertia or capacity and aggregated into a single equivalent generator. (Sending-end equivalent generator power angle) Defined as:

[0051] in, For generator The inertial time constant. Similarly, the power angle of the receiving end isomechanical unit. for:

[0052] Define the inter-provincial work angle difference , This is the power angle stability threshold. It is calculated in real-time during the time-domain simulation. If at any time satisfy:

[0053] If this is determined to be a transient power angle instability, the simulation example is immediately terminated, and the process moves to the next anticipated fault or operating mode assessment; since the equivalent machine aggregation calculation only requires The number of addition and multiplication operations is much smaller than the number of cross-region traversals. This fast prediction can terminate most unstable cases in advance, significantly reducing the computational burden.

[0054] As one example, if in the first-level discrimination If the condition is consistently true, then proceed to the second level of detailed verification. At this point, monitor each generator pair between the sending and receiving ends, i.e., all... and The combination of [various elements]. For each inter-regional generator pair, its relative power angle difference is defined as: Set a stability threshold for the second-level discrimination. (This disclosure is taken) ). Calculate the power angle difference for all cross-zone pairs. If any pair exists... At any time t satisfy:

[0055] If the system is unstable due to transient power angle, it is determined to be stable; otherwise, it is determined to be stable.

[0056] Traditional transient stability assessment methods require monitoring all generator pairs from the start of the simulation, including those within the sending end, receiving end, and cross-regional pairs. The total number of generator pairs that need to be monitored is approximately:

[0057] The two-level discrimination strategy adopted in this disclosure, in the worst case, requires first completing the isometry aggregation calculation (complexity...). Then complete the cross-region traversal (complexity) This eliminates the need for monitoring within the region. In the instability case, the first stage can be terminated early, requiring only a fraction of the computational cost. This saves a lot of time compared to traditional methods.

[0058] Research and practice show that when a severe fault occurs near the power limit of an inter-provincial transmission section, the instability mode mainly manifests as the overall loss of synchronization between the sending-end generator group and the receiving-end generator group. However, generators within the same province, due to their close electrical distance and interconnectedness, typically exhibit smaller relative power angle swings and do not experience instability prior to inter-provincial instability. Therefore, ignoring the relative swing of generators within a province is an engineeringly acceptable simplification.

[0059] Step 32: To overcome the bottleneck of long computation time in traditional time-domain simulation, this disclosure proposes a hybrid acceleration strategy of "coarse-grained parallelism + fine-grained variable step size" specifically for transient power angle stability assessment scenarios. Existing research either uses parallel acceleration alone or variable step size integration alone. This disclosure organically integrates the two and designs a dynamic step size adjustment strategy based on maximum angular acceleration to address the special characteristics of transient power angle stability assessment—intense dynamics during faults and gradual decay after faults. This significantly reduces the number of integration steps while ensuring the accuracy of power angle simulation, achieving synergistic acceleration in both dimensions.

[0060] Specifically, in terms of coarse-grained parallelism, the combination set of "operation mode + fault location" to be evaluated is used. Split into A subset of each other Distributed to Execution is performed in parallel on each computing node. Each node independently completes its assigned time-domain simulation task. The overall computation time is determined by the slowest node, and the speedup is theoretically close to [missing information - likely a specific value]. .

[0061] For fine-grained variable-step integration, a fourth-order Runge-Kutta method with variable step size is used for numerical integration within a single simulation task. The step size is adjusted based on the estimated local truncation error. :

[0062] in, The current step size, This is a preset error tolerance. Simultaneously, monitoring indicators for the dynamic intensity of the system are introduced. .when At that time, the step size is forcibly limited to (e.g., 0.001s); when At that time, the step size is allowed to increase to (e.g., 0.02s). By dynamically adjusting the step size, the total number of integration steps can be reduced while maintaining accuracy.

[0063] Let the original fixed step size integration steps for a single simulation be... After changing the step size, the average step size increases to The number of steps is reduced to Combining The roads run in parallel, and the total acceleration ratio is approximately .

[0064] Step 33: To comprehensively assess the cross-sectional transmission capacity, a series of operating modes reflecting different power exchange levels need to be generated. This disclosure proposes an automatic generation and adjustment strategy for operating modes based on reserve capacity reallocation and the maintenance of the proportion of renewable energy, including two parts: automatic generation of operating modes for reserve capacity reallocation and scenario generation based on the impact of different renewable energy proportions. Figure 2 This is a schematic diagram of a method for generating an operation mode based on the redistribution of generator reserve capacity while maintaining a constant proportion of new energy output.

[0065] The automatic generation of the operation mode for the redistribution of reserve capacity includes: (1) First, set the power increment target. Let the current cross-sectional transmission power be... The target increase is After one adjustment, the target power of the cross-section is... .

[0066] Then, the output of thermal power units in the sending-end power grid is redistributed. The current output of all thermal power units in the sending-end power grid is obtained. and maximum output Calculate the increase in reserve capacity:

[0067] Total increase in reserve capacity is The power increment is allocated according to the reserve capacity ratio of each unit. (Considering network loss coefficient) , ):

[0068] when season Calculate the reduced reserve capacity of thermal power units:

[0069] Total reduction in reserve capacity is The power generation capacity that needs to be reduced at the sending end is: Allocation based on the percentage of reserve capacity reduced for each generating unit:

[0070] If a unit exceeds the upper or lower limit after adjustment, the upper / lower limit will be taken and the excess / insufficiency will be redistributed to other units.

[0071] The output of renewable energy at the sending end remains unchanged. The output of all wind farms and photovoltaic power plants within the sending-end grid remains unchanged proportionally to their installed capacity. Let the... The installed capacity of each wind farm is Current output is Then the output coefficient Adjusted output constant.

[0072] The load on the receiving-end power grid increases proportionally. To absorb the increased power, the active power load within the receiving-end power grid is increased proportionally to the original power ratio of each load node:

[0073] In the formula, The initial total load of the receiving-end power grid, For nodes The initial load.

[0074] By iteratively calling the function, a small increment is added each time. By performing power flow calculations and transient stability checks, a series of operating modes from the ground state to the limiting state can be obtained.

[0075] Furthermore, the process of generating scenarios influenced by different proportions of new energy sources includes: This disclosure supports the analysis of the impact of renewable energy penetration rate on cross-sectional power transmission capacity.

[0076] First, set a target for the proportion of renewable energy. Separately set target values ​​for the proportion of total renewable energy output to total power generation in both the sending-end and receiving-end power grids, denoted as [value missing]. and :

[0077] Then, the output of new energy sources is adjusted proportionally. Under the basic operating mode, the total power generation output of both the sending and receiving grids remains constant, while the output of all new energy units is adjusted proportionally to achieve the target proportion. Let the total output of new energy sources at the sending end under the basic mode be... The target total output is Then the adjustment coefficient is:

[0078] The new output of each wind farm / solar power plant is set as follows: .

[0079] Next, the thermal power output will be redistributed. After adjusting the output of new energy sources, the total power generation output of the sending-end grid will change. To maintain a constant cross-sectional power level, the thermal power output needs to be readjusted. The new total thermal power output is:

[0080] Then, in accordance with the proposed method for redistributing reserve capacity, the new total thermal power output task will be allocated to each thermal power unit.

[0081] Finally, the relationship between power transmission capacity and the proportion of new energy sources is analyzed. (In several different...) In combination, the complete cross-sectional transmission capacity assessment process is executed separately to obtain the corresponding limit transmission power. Through analysis Follow The change curve can quantitatively reveal the impact of new energy penetration rate on power transmission capacity.

[0082] Step 4: Achieve high-precision, high-efficiency assessment and closed-loop improvement of power transmission capacity at key cross sections.

[0083] Step 41: To evaluate the transient stability of the cross section under extreme operating conditions, this disclosure defines a typical severe fault scenario and implements automated configuration.

[0084] (1) First, perform initial state configuration. Configure the key transmission sections to be evaluated. One of the circuits in an AC double-circuit line (e.g., line 1) Set the line to "maintenance shutdown" status. The specific operation is as follows: set the on / off status of this line to shutdown, simulating N-1 operating conditions. At this time, the set of remaining lines in the section is... .

[0085] (2) Then perform fault triggering and clearing settings. On the remaining running single-circuit line (e.g.) A three-phase metallic short-circuit fault is installed at either the sending or receiving busbar of the circuit. The time of fault occurrence is recorded as _____. The fault duration is set to... Second, The value is determined by the actual operating time setting value of the line protection device, and is usually taken as... or Fault clearing is achieved by the protection device activating and simultaneously disconnecting the faulty circuit. And another line .

[0086] The automated configuration parameters for fault scenarios include: troubleshooting route traversal, fault location, and fault duration. The network topology after fault clearing. This fault configuration method simulates one of the most extreme scenarios in power grid operation and can effectively test the transient power angle stability of the cross section.

[0087] Step 42: When the ultimate transmission capacity of the critical section is calculated... Subsequently, if the actual transmission power of the section under the current operating mode is monitored in real time... Exceed This disclosure proposes a closed-loop adjustment method, including: (1) First, determine if the power exceeds the limit. Collect data from key sections. The sum of real-time power of all lines:

[0088] like If so, the adjustment process will be triggered.

[0089] (2) Then set the power reduction target. Set the safe power target value:

[0090] In the formula, For the reserved power margin (this disclosure takes) (That is, a 5% margin). The amount of power that needs to be reduced is:

[0091] (3) Next, implement the strategy of reducing generator output in the sending-end power grid. Within the sending-end power grid, prioritize reducing the output of thermal power units with lower peak-shaving capacity. Let the first... The current output of the Taiwan thermal power unit is Minimum technical output is Then its reserve capacity will be reduced to Total reserve capacity reduced by The reduction amount is allocated according to the reserve capacity ratio of each unit:

[0092] (4) The updated output is If a certain unit's adjusted value is lower than... Then take The difference will then be redistributed to other units.

[0093] (5) Perform iterative adjustments and power flow verification. After one round of output adjustment, recalculate the power flow. If the power flow does not converge or the cross-sectional power... Still greater than If the condition is met, proceed to the next iteration until the requirement is satisfied. The iteration termination condition is:

[0094] in The allowable deviation threshold (e.g., 10MW).

[0095] (6) Finally, optional load adjustment at the receiving end can be implemented. If system power imbalance occurs after the sending end reduces its output, a portion of the interruptible load of the receiving end grid can be reduced synchronously and proportionally according to dispatch requirements. The load reduction should match the reduction in sending end output. The adjusted operating mode can be issued as a dispatch instruction to the power plant and load side. Through the above closed-loop adjustment method, a clear and executable over-limit handling strategy can be provided for grid dispatchers, ensuring that the cross-sectional power always operates within the safe boundary.

[0096] Simulation verification Using a real-world system where a sending-end power grid transmits power to a receiving-end power grid via AC / DC transmission channels as a specific application scenario, this study verifies the effectiveness of the proposed method for assessing and improving cross-sectional transmission capacity, considering inter-provincial transient power angle stability constraints. The example system includes a sending-end power grid, a receiving-end power grid, multiple 1000kV AC transmission channels (denoted as channels A1 / A2, B1 / B2, and C1 / C2), and one ±800kV DC transmission channel. Under different renewable energy outputs, the proposed cross-sectional transmission capacity assessment method is used to gradually reduce the sending-end load, effectively increasing the transmitted power. Three-phase short-circuit faults are applied to each channel at different power levels. Time-domain simulation is used to determine the system's transient power angle stability, thereby determining the cross-sectional transmission capacity.

[0097] The method disclosed herein was used to evaluate the power grid in 2025. As the sending-end load gradually decreased, the cross-sectional power gradually increased, and the system first became unstable after a fault in channel B1 / B2. The calculated cross-sectional transmission capacity of the power grid in 2025 was 14720MW, and the first instability fault point was a fault in the double-circuit channel B1 / B2. The same method was used to evaluate the power grid in 2030 (with the newly added double-circuit channel A1 / A2), and the cross-sectional transmission capacity was found to be 20041MW, an increase of 36.1% compared to 2025. The first instability fault point was still the double-circuit channel B1 / B2. The cross-sectional transmission capacity and the first instability fault point of the power grid under each year are summarized in Table 1.

[0098] Table 1. Transmission capacity of cross sections under different grid levels.

[0099] To visually demonstrate the difference in power response under transient power angle stability and instability conditions, two typical operating modes in the 2030 grid structure were selected, and the power response curves of three transmission channels (A1 / A2, B1 / B2, C1 / C2) under stable scenarios were presented. Figure 3 The total cross-sectional power is 20041MW. After a three-phase short-circuit fault is applied to channel B1 / B2, the system remains transiently stable, and the power response curves are shown in the unstable scenario. Figure 4 The power response curves of the system exhibiting transient power angle instability after the same fault is applied, with a total cross-sectional power of 20435MW, slightly higher than the limit value.

[0100] Depend on Figure 3 As can be seen, the power of each channel briefly drops during the fault, but recovers rapidly after the fault is cleared, undergoes slight decaying oscillations, and eventually converges to a new steady-state value, maintaining transient stability of the system. Instability scenarios include... Figure 4 As shown, the power of channels B1 / B2 oscillated briefly after the fault, then dropped sharply and oscillated significantly. The relative power angle between the sending and receiving end units continued to widen, eventually exceeding the 180° stability boundary, and the system lost synchronization.

[0101] To reveal the impact of renewable energy share on cross-sectional transmission capacity, this paper applies the renewable energy share scenario generation method proposed in this disclosure. Under the 2030 grid framework, while keeping boundary conditions such as DC power transmission and AC tie-line power constant, the output ratio of renewable energy and thermal power is systematically changed to obtain cross-sectional transmission capacity under different renewable energy penetration rates. Table 2 shows the comparative results for some typical operating conditions. When the renewable energy share increases from 33% to 61%, the cross-sectional transmission capacity increases from 20041MW to 20548MW; when the renewable energy share further increases to 70%, the transmission capacity decreases to 20445MW, and the system again reaches a stable boundary. The above results show that the method of this disclosure can accurately capture the nonlinear relationship between renewable energy share and transmission capacity, find the optimal ratio range, and provide a scientific basis for renewable energy planning.

[0102] Table 2. Transmission Capacity of Power Grid Sections under Different Renewable Energy Proportions by 2030

[0103] Based on the "inter-province-intra-province" decoupled transient power angle stability discrimination method proposed in this disclosure, and combined with the extended equal area rule, the acceleration and deceleration areas of the two typical operating modes in Table 4 were quantitatively analyzed. The calculation results show that the acceleration area of ​​operating mode 2 is smaller than that of operating mode 1, while the deceleration area is larger, and the transient stability margin changes from negative to positive. Operating mode 2 has higher renewable energy output, and during the fault period, the active power drop is greater due to low voltage ride-through, resulting in a decrease in equivalent mechanical power and slower rotor acceleration during the fault period. The power angle is smaller at the time of fault clearing, and the acceleration area is smaller. Simultaneously, the power of channels C1 / C2 is lower in operating mode 2, the voltage recovery is faster after the fault, and the amplitude of the power angle curve is larger, resulting in an increased deceleration area.

[0104] Based on the closed-loop adjustment method for exceeding power limits proposed in this disclosure, using the grid transmission capacity of 20041MW in 2030 as a benchmark, when the actual power of the cross-section reaches 21080MW (exceeding the limit by approximately 5.2%), the output of the sending-end thermal power units is reduced according to the proportion of reserve capacity reduction. After two rounds of iterative adjustments, the cross-section power is reduced to 19950MW, meeting safety constraints. The adjustment process is smooth and the power flow converges. This method provides clear and quantifiable steps for handling exceeding limits.

[0105] In summary, the cross-sectional transmission capacity assessment and improvement method proposed in this disclosure, which considers the transient power angle stability constraints between provinces, has significant beneficial effects in terms of assessment accuracy, adaptability to new energy sources, mechanism revelation, and practical adjustment. It can provide effective technical support for the planning, operation, and control of the sending and receiving end power grids.

[0106] Example 2 One embodiment of this disclosure provides a cross-sectional transmission capacity assessment system considering transient power angle stability constraints, comprising: The initialization module is used to obtain the basic operating mode of the power grid given the power grid topology; The critical section identification module is used to construct a three-dimensional comprehensive index based on the basic operation mode of the power grid, introduce filtering conditions based on the dual regional and electrical affiliation relationship, and use the three-dimensional comprehensive index to screen and aggregate power grid lines to identify critical transmission sections. The optimization model construction module is used to construct an optimization model for power transmission capacity assessment with the goal of maximizing the transmission power of the key transmission section and with the transient power angle stability between the sending-end grid and the receiving-end grid as the core constraint. The assessment and configuration enhancement module is used to design a fast and stable discrimination criterion for "inter-province-intra-province" decoupling. It integrates parallel computing and variable step size simulation mechanism, and automatically generates and adjusts strategies based on the operation mode of reserve capacity redistribution and maintaining the proportion of new energy to solve the transmission capacity assessment optimization model. Ultimately, it achieves high-precision and high-efficiency assessment and closed-loop enhancement of transmission capacity in key sections.

[0107] Example 3 One embodiment of this disclosure provides a computer program product, including a computer program that, when executed by a processor, implements the method for evaluating cross-sectional transmission capacity considering transient power angle stability constraints.

[0108] Example 4 One embodiment of this disclosure provides a non-transitory computer-readable storage medium for storing computer instructions. When executed by a processor, the computer instructions implement the cross-sectional transmission capacity assessment method considering transient power angle stability constraints.

[0109] Example 5 One embodiment of this disclosure provides an electronic device, including a processor, a memory, and a computer program; wherein the processor is connected to the memory, and the computer program is stored in the memory. When the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to perform the cross-sectional transmission capacity assessment method considering transient power angle stability constraints.

[0110] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0111] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0112] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. A method for evaluating the transmission capability of a section considering the transient power angle stability constraint, characterized in that, The application relates to a method for evaluating and improving the transmission capacity of a power grid, and belongs to the field of power grid operation and control. The method comprises the following steps: obtaining a basic operation mode of a power grid given a power grid topology; based on the basic operation mode of the power grid, introducing a filtering condition based on a geographical-electric dual belonging relationship, constructing a three-dimensional comprehensive index, using the three-dimensional comprehensive index to screen and aggregate the power grid lines, and identifying a key power transmission section; taking the maximization of the transmission power of the key power transmission section as a target, and taking the transient power angle stability between the sending end power grid and the receiving end power grid as a core constraint, constructing a transmission capacity evaluation optimization model; 2. The method for assessing the transmission capability of a section considering transient power angle stability constraints according to claim 1, wherein, designing a fast stability discrimination criterion decoupled from the "inter-provincial-intra-provincial" relationship, fusing a parallel computing and variable step simulation mechanism, and solving the transmission capacity evaluation optimization model based on a standby capacity redistribution and an operation mode automatic generation and adjustment strategy based on a new energy proportion keeping, and finally realizing high-precision and high-efficiency evaluation and closed-loop improvement of the transmission capacity of the key section. The method for identifying the key power transmission section based on the basic operation mode of the power grid, introducing the filtering condition based on the geographical-electric dual belonging relationship, constructing the three-dimensional comprehensive index, and using the three-dimensional comprehensive index to screen and aggregate the power grid lines comprises the following steps: the filtering condition based on the geographical-electric dual belonging relationship is introduced, so that the identified section not only electrically undertakes an important inter-provincial power transmission task, but also is clearly attributed to a specific sending end province and a receiving end province in the power grid partition, and misidentification of a strong connection line in the same provincial area as an inter-provincial key section is avoided; a three-dimensional comprehensive index fusing an electric intermediate number, a power flow transfer factor and a provincial attribution condition is constructed, and the electric intermediate number and the power flow transfer factor of the line are calculated respectively; 3. The method for assessing the transient angle stability constraint considered cross-sectional power transfer capability according to claim 1, wherein, a provincial attribution condition and a comprehensive vulnerability index are constructed, and the sections are aggregated to obtain the key power transmission section. The method for constructing the transmission capacity evaluation optimization model taking the maximization of the transmission power of the key power transmission section as a target and taking the transient power angle stability between the sending end power grid and the receiving end power gridas a core constraint comprises the following steps: a target function of the maximization of the active transmission power of the target key power transmission section is constructed; the transient power angle stability between the sending end power grid and the receiving end power grid is taken as a core constraint, so that the maximum relative power angle difference between any generator in the sending end power grid and any generator in the receiving end power grid is less than a preset stability threshold after a contingency occurs; 4. The method for assessing the transient angle stability constraint considered cross-sectional power transfer capability according to claim 1, wherein, static security constraints other than the core constraint are constructed, and the static security constraints include a node power balance constraint, an upper and lower limit constraint of the active power output of a generator, an upper and lower limit constraint of the reactive power output of the generator, a node voltage amplitude constraint and a line thermal stability limit constraint. The method for designing the fast stability discrimination criterion decoupled from the "inter-provincial-intra-provincial" relationship comprises the following steps: A stable threshold is set for the second level discrimination process, the power angle difference of all cross-zone pairs is calculated, if there is any pair at any time t satisfies the power angle difference greater than the stable threshold, it is determined that the system transient power angle is unstable; otherwise, it is determined to be stable.

5. The method for assessing the transient angle stability constraint considered cross-sectional power transfer capability according to claim 1, wherein, The fast stability discrimination criterion comprises a two-stage discrimination strategy, the first stage adopts equivalent machine aggregation for fast pre-judgment, and the second stage carries out detailed verification of all inter-provincial generator pairs for the case that the pre-judgment result is stable, and ignores the relative swing of the generators in each province; The parallel computing and variable step simulation mechanism fuses parallel acceleration and variable step integration, and is designed based on a maximum angle acceleration step dynamic adjustment strategy according to the characteristics that the dynamic is intense during the fault period and gradually decays after the fault of the transient power angle stability evaluation, significantly reduces the integral step number on the premise of ensuring the power angle simulation precision, and realizes two-dimensional collaborative acceleration. In terms of coarse-grained parallelism, the combination set of operating modes and fault locations to be evaluated is split into multiple independent subsets, distributed to multiple computing nodes and executed in parallel; each node independently completes its assigned time-domain simulation task, and the overall computation time is determined by the slowest node; In terms of fine-grained variable-step integration, within a single simulation task, a variable-step fourth-order Runge-Kutta method is used for numerical integration.

6. The method for assessing the transient angle stability constraint considered cross-sectional power transfer capability according to claim 1, wherein, The operating mode automatic generation and adjustment strategy based on backup capacity redistribution and new energy proportion retention includes operating mode automatic generation of backup capacity redistribution and scenario generation of different new energy proportion impacts, and the operating mode automatic generation of backup capacity redistribution includes: Setting a power increment target; Redistributing the output of thermal power units in the sending-end power grid; If a unit exceeds the upper limit or lower limit after adjustment, the upper limit or lower limit is taken, and the excess or insufficient part is redistributed to other units; The scenario generation of different new energy proportion impacts includes: Setting a new energy proportion target; Adjusting the new energy output in equal proportion; Redistributing the thermal power output again; Finally, analyze the relationship between the power transmission capacity and the new energy proportion.

7. A system for evaluating the transmission capability of a section of a power grid taking into account transient power angle stability constraints, characterized in that, It includes: An initialization module for giving a power grid topology and obtaining a basic operating mode of the power grid; A key section identification module for introducing a filtering condition based on regional-electric dual attribution relationship based on the basic operating mode of the power grid, constructing a three-dimensional comprehensive index, screening and aggregating the power grid lines using the three-dimensional comprehensive index, and identifying the key power transmission section; An optimization model construction module for maximizing the transmission power of the key power transmission section as the target and taking the transient angle stability between the sending-end power grid and the receiving-end power grid as the core constraint to construct a power transmission capacity evaluation optimization model; An evaluation and configuration improvement module for designing a decoupled fast stability criterion between provinces and within a province, integrating parallel computing and variable-step simulation mechanisms, and solving the power transmission capacity evaluation optimization model based on the operating mode automatic generation and adjustment strategy of backup capacity redistribution and new energy proportion retention to finally realize high-precision and high-efficiency evaluation and closed-loop improvement of the key section power transmission capacity.

8. A computer program product comprising a computer program, characterized in that, The computer program is executed by the processor to realize the section power transmission capacity evaluation method considering transient angle stability constraints according to any one of claims 1-6.

9. A non-transitory computer-readable storage medium, comprising: The non-transitory computer readable storage medium is used to store computer instructions, which are executed by the processor to realize the section power transmission capacity evaluation method considering transient angle stability constraints according to any one of claims 1-6.

10. An electronic device, comprising: It includes: A processor, a memory and a computer program; wherein the processor is connected with the memory, and the computer program is stored in the memory; when the electronic device is running, the processor executes the computer program stored in the memory to make the electronic device execute the section power transmission capacity evaluation method considering transient angle stability constraints according to any one of claims 1-6.

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