Receiving end power grid operation evaluation method and system based on flexible direct current transmission

Abstract

The invention discloses a receiving-end power grid operation evaluation method and system based on flexible direct current transmission, and the method comprises the steps: dividing a receiving-end power grid into a plurality of independent electrical influence domains based on the real-time operation parameters of the receiving-end power grid by taking the access point of each flexible direct current transmission converter station as a division reference; in each electrical influence domain, presetting an operation control mode of the flexible DC power transmission converter station, and synchronously acquiring electrical quantity dynamic response data of key nodes in the electrical influence domains; automatically extracting core indexes for representing interaction characteristics of the alternating current and direct current system; constructing a risk assessment model for assessing the operation state of each electrical influence domain, calculating the risk contribution degree of each constituent element, and identifying a key risk propagation path in the receiving-end power grid; and judging the overall comprehensive operation state of the receiving-end power grid, and generating coordinated operation control boundary parameters of the flexible direct-current power transmission converter station. By accurately evaluating the operation risk of the receiving-end power grid, an evaluation-regulation closed loop is realized, and the safety and stability of the power grid are ensured.

Description

Technical Field

[0001] This invention relates to the field of smart grid technology, and specifically to a method and system for evaluating the operation of the receiving-end power grid based on flexible DC transmission. Background Technology

[0002] With the rapid development and large-scale grid connection of new energy power generation technologies, the power supply structure and operating characteristics of power systems have undergone profound changes. Flexible DC transmission technology, with its advantages of flexible control, rapid response, and low harmonic pollution, has become one of the core technical means to solve the problems of new energy consumption, cross-regional power transmission, and grid interconnection. As an important receiving end of the flexible DC transmission system, the operating status of the receiving-end grid directly affects the safety, stability, and power supply reliability of the entire AC / DC hybrid grid. Currently, the receiving-end grid often connects to multiple flexible DC converter stations, and the interaction between AC and DC systems is becoming increasingly complex. Risks such as static voltage fluctuations, transient power angle instability, and converter station overload are intertwined and superimposed, placing higher demands on the operation assessment and control of the receiving-end grid. It is urgent to establish a precise operation assessment method adapted to the characteristics of AC / DC hybrid grids to provide technical support for the safe and stable operation of the power grid.

[0003] In existing technologies, research on the operation assessment of the receiving-end power grid is mostly based on the assessment framework of traditional AC power grids, or it involves isolated analysis of single operating indicators of flexible DC transmission systems. Some schemes adopt a holistic power grid assessment model, failing to consider the differences in the local impact of different flexible DC converter stations on the surrounding power grid, and directly conducting a global assessment of the receiving-end power grid. Other schemes collect the converter station's own operating parameters (such as DC voltage and active power) and combine them with indicators such as voltage and frequency of the traditional AC power grid to construct a simple threshold judgment model to achieve preliminary monitoring of the operating status. In addition, existing assessment methods often focus on the identification of single risk types, such as only focusing on the risk of static voltage exceeding limits or the risk of converter station equipment overload, and the control strategy formulation often adopts an independent control mode, with a lack of coordination among the operating control parameters of each converter station.

[0004] However, the most critical shortcoming of existing technologies lies in their failure to construct an integrated technical system of "zonal assessment - precise characterization - risk tracing - coordinated control" adapted to the interactive characteristics of AC / DC systems. This results in insufficient accuracy and coordination in assessment and control. Specifically, existing solutions neither finely zonate the local interactive impact characteristics formed after the flexible DC converter station is connected, nor do they have a dedicated core indicator system that can comprehensively characterize the AC / DC coupling effect. Furthermore, they have not established a risk assessment model that considers the superposition of multiple risk types and the interaction between indicators, making it difficult to accurately identify key risk sources and propagation paths. At the same time, the assessment results are severely disconnected from the converter station control strategy, making it impossible to dynamically optimize the coordinated operation boundary parameters of each converter station based on the assessment conclusions. This makes it difficult to form a closed-loop mechanism of "assessment guiding control, and control ensuring safety," ultimately resulting in the inability to effectively predict and prevent operational risks of the receiving-end power grid in complex AC / DC interaction scenarios, thus hindering the improvement of the power grid's safe and stable operation level. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method and system for evaluating the operation of the receiving-end power grid based on flexible DC transmission, which aims to solve the above-mentioned problems described in the prior art.

[0006] A first aspect of the present invention is to provide a method for evaluating the operation of a receiving-end power grid based on flexible DC transmission, the method comprising: Based on the real-time operating parameters of the receiving-end power grid, and taking the access point of each flexible DC transmission converter station as the dividing benchmark, the receiving-end power grid is divided into several independent electrical influence domains. Within each of the aforementioned electrical influence domains, a preset operation control mode for the flexible DC transmission converter station is established, and dynamic response data of electrical quantities of key nodes within the electrical influence domain are collected synchronously. Based on the dynamic response data of electrical quantities, core indicators for characterizing the interaction characteristics of AC / DC systems are automatically extracted. Based on the extracted core indicators, a risk assessment model is constructed to evaluate the operating status of each electrical influence domain, and the risk contribution of each component is calculated based on the risk assessment model to identify the key risk propagation paths within the receiving-end power grid. Based on the assessment results of each of the electrical influence domains, the overall integrated operation status of the receiving-end power grid is determined, and the coordinated operation control boundary parameters of the flexible DC transmission converter station are generated.

[0007] According to one aspect of the above technical solution, the step of automatically extracting core indicators for characterizing the interaction characteristics of AC / DC systems based on the electrical quantity dynamic response data specifically includes: The collected dynamic response data of electrical quantities are processed in a time-series segmentation manner to filter out the effective data during periods of intense AC / DC power interaction, and simultaneously remove steady-state redundant data and abnormal disturbance noise. Based on the filtered valid data, three core indicators were extracted from the converter station outlet: AC / DC voltage amplitude ratio, frequency response lag time, and reactive power interaction coupling coefficient. These were used to construct a set of interactive characteristic indicators corresponding to the AC / DC system.

[0008] According to one aspect of the above technical solution, the step of extracting three core indicators—AC / DC voltage amplitude ratio, frequency response lag time, and reactive power interaction coupling coefficient—from the filtered effective data to construct a set of interaction characteristic indicators corresponding to the AC / DC system specifically includes: For the AC / DC voltage amplitude ratio index at the converter station outlet, the effective value of AC voltage and the average value of DC voltage at the same time node are extracted from the filtered data, the ratio of the two is calculated and abnormal extreme values ​​are removed, and the time-series average value is taken as the final determined value of the index. The time difference between the issuance of the frequency command at the converter station and the time when the frequency of the key node at the receiving end reaches a stable state is extracted and used as the frequency response lag time. The reactive power interaction coupling coefficient is calculated by analyzing the time-series correlation between active power and reactive power. The three core indicators are standardized and normalized to eliminate the differences in the dimensions of each indicator and integrate them into a unified set of interactive feature indicators corresponding to AC and DC systems.

[0009] According to one aspect of the above technical solution, based on the extracted core indicators, a risk assessment model is constructed to evaluate the operating status of each of the aforementioned electrical influence domains. Based on the risk assessment model, the risk contribution of each component is calculated, and key risk propagation paths within the receiving-end power grid are identified. The steps include: Based on the aforementioned core indicators, individual risk indicators corresponding to static voltage over-limit risk, transient power angle instability risk, and converter station overload risk are calculated respectively. Each individual risk indicator is compared with a preset corresponding risk threshold, and a comprehensive risk assessment value for the electrical influence domain is generated through weighted fusion processing. Based on the determination result that the comprehensive risk assessment value exceeds the preset alarm threshold, the contribution of each core indicator to the comprehensive risk assessment value is calculated. The physical links corresponding to the core indicators with the highest contribution are identified as key risk sources within the current electrical influence domain. Based on the power grid topology, the electrical connection paths strongly correlated with the risk sources are traced to identify the key risk propagation paths within the receiving-end power grid.

[0010] According to one aspect of the above technical solution, the step of calculating the contribution of each core indicator to the comprehensive risk assessment value based on the determination result that the comprehensive risk assessment value exceeds the preset alarm threshold includes: Calculate the original contribution value of each core indicator in the single risk indicator, and normalize each original contribution value to obtain the normalized contribution factor corresponding to each core indicator. The normalized contribution factor is multiplied by the weight coefficient of the corresponding individual risk indicator to calculate the direct contribution of each core indicator to the comprehensive risk assessment value. Based on the correlation between the core indicators, the indirect contribution caused by their interaction is calculated, and the sum of the direct contribution and the indirect contribution is taken as the final contribution of the core indicators to the comprehensive risk assessment value.

[0011] According to one aspect of the above technical solution, based on the determination result that the comprehensive risk assessment value exceeds the preset alarm threshold, the calculation expression for the contribution of each core indicator to the comprehensive risk assessment value is as follows: ; In the formula, C i Core indicators i The final contribution, where n is the total number of core indicators. α i Core indicators i The corresponding normalized contribution factor, w i Core indicators i The corresponding weighting coefficients, λ As an indirect contribution adjustment coefficient, ρ ik Core indicators i With core indicators k The correlation coefficient between them α k Core indicators k The corresponding normalized contribution factor.

[0012] According to one aspect of the above technical solution, the steps of determining the overall integrated operating status of the receiving-end power grid and generating the coordinated operation control boundary parameters of the flexible DC transmission converter station, based on the evaluation results of each of the aforementioned electrical influence domains, include: Based on the comprehensive risk assessment value of each electrical influence domain and the identified key risk propagation paths, the overall comprehensive operating status score of the receiving-end power grid is calculated using a weighted aggregation method. The overall integrated operation status score is compared with the preset safe operation threshold. When the score is lower than the safe operation threshold, the power and voltage control command boundary parameters of each flexible DC transmission converter station are optimized in reverse according to the degree of influence of each converter station on the key risk propagation path, so as to form a coordinated operation control boundary.

[0013] A second aspect of the present invention is to provide a receiving-end power grid operation evaluation system based on flexible DC transmission, applied to the method described in the above-mentioned technical solution, the system comprising: The electrical zone division module is used to divide the receiving-end power grid into several independent electrical influence domains based on the real-time operating parameters of the receiving-end power grid and the access point of each flexible DC transmission converter station. The response data acquisition module is used to preset the operation control mode of the flexible DC transmission converter station in each of the electrical influence domains and synchronously acquire the dynamic response data of electrical quantities of key nodes in the electrical influence domains. The core indicator extraction module is used to automatically extract core indicators that characterize the interaction characteristics of AC / DC systems based on the dynamic response data of electrical quantities. The risk path identification module is used to construct a risk assessment model for evaluating the operating status of each electrical influence domain based on the extracted core indicators, and to calculate the risk contribution of each component based on the risk assessment model, thereby identifying the key risk propagation paths within the receiving-end power grid. The boundary parameter generation module is used to integrate the evaluation results of each of the electrical influence domains, determine the overall integrated operation status of the receiving-end power grid, and generate the coordinated operation control boundary parameters of the flexible DC transmission converter station.

[0014] A third aspect of the present invention is to provide a readable storage medium having computer instructions stored thereon, which, when executed by a processor, implement the steps of the method described in the above-described technical solution.

[0015] A fourth aspect of the present invention is to provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the method described in the above technical solutions.

[0016] Compared with existing technologies, the advantages of using the receiving-end power grid operation evaluation method and system based on flexible DC transmission as shown in this invention are as follows: This invention constructs an integrated system for evaluating and regulating the operation of the receiving-end power grid, adapted to the characteristics of AC / DC hybrid interconnection, effectively addressing the core shortcomings of existing technologies. By dividing independent electrical influence domains based on the flexible DC converter station access point, it achieves refined zonal evaluation of the power grid's operating status, accurately matching the localized characteristics of AC / DC interaction. Based on dynamic response data of electrical quantities, it extracts specific core indicators and constructs a standardized indicator set, comprehensively and accurately characterizing the interactive characteristics of the AC / DC system. Utilizing a risk assessment model that covers multiple risk types and considers both the direct and indirect contributions of indicators, it significantly improves the accuracy of identifying key risk sources and propagation paths. Finally, by comprehensively evaluating the results of each region, it determines the overall state of the power grid and reverse-optimizes the generation of control boundary parameters for the coordinated operation of converter stations, forming a closed-loop linkage mechanism of "evaluation-regulation." This scheme significantly improves the accuracy and efficiency of receiving-end power grid operation evaluation, effectively enhances the ability to predict and prevent key risks, ensures the safe and stable operation of AC / DC hybrid power grids in scenarios with multiple converter stations, and provides reliable technical support for large-scale consumption of new energy and cross-regional power transmission. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 A flowchart illustrating the receiving-end power grid operation evaluation method based on flexible DC transmission provided in an embodiment of the present invention; Figure 2 This is a structural block diagram of a receiving-end power grid operation evaluation system based on flexible DC transmission, provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0019] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0020] Unless otherwise defined, 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Example 1 Please see Figure 1 The first embodiment of the present invention provides a method for evaluating the operation of a receiving-end power grid based on flexible DC transmission, the method comprising steps S10-S50: Step S10: Based on the real-time operating parameters of the receiving-end power grid, and taking the access point of each flexible DC transmission converter station as the dividing benchmark, the receiving-end power grid is divided into several independent electrical influence domains.

[0022] It should be noted that the receiving-end power grid is the core area for receiving flexible DC transmission power. The connection of each flexible DC converter station will form a specific local electrical radiation range. The operating characteristics of different converter stations (such as power regulation capability and control strategy) have significant differences in their impact on the surrounding power grid. If the entire power grid is evaluated in a unified manner, the evaluation results will be distorted due to the superposition of electrical characteristics in different areas.

[0023] In this embodiment, real-time operating parameters of the receiving-end power grid are acquired, including instantaneous data such as voltage amplitude, current magnitude, power flow, and frequency stability at each node of the power grid. This data accurately reflects the current operating conditions of the power grid, ensuring a high degree of match between the classification results and actual operating conditions. Specifically, based on the converter station access point, each converter station and its directly affected surrounding power grid are defined as an independent electrical influence domain. This allows subsequent assessments to focus on the interaction between a single converter station and the corresponding regional power grid, avoiding the impact of cross-regional electrical interference on the accuracy of the assessment.

[0024] Step S20: Within each of the electrical influence domains, a preset operation control mode for the flexible DC transmission converter station is established, and dynamic response data of electrical quantities of key nodes within the electrical influence domain are collected synchronously.

[0025] It should be noted that common control modes for flexible DC converter stations include constant power control, constant voltage control, and constant frequency control. Presetting a fixed control mode can ensure that data acquisition is carried out in a controllable and uniform experimental environment, avoiding data fluctuations caused by frequent switching of control modes, and ensuring the comparability and validity of the data.

[0026] In this embodiment, when synchronously collecting dynamic response data of electrical quantities at key nodes within the electrical influence domain, the selection of key nodes has a clear engineering orientation, typically including converter station outlet nodes, important load center nodes within the region, and inter-regional tie line nodes. The changes in electrical quantities at these nodes can centrally reflect the core characteristics of the AC / DC system interaction process. Furthermore, the dynamic response data of electrical quantities differs from static data, covering complete curves of parameters such as voltage, current, power, and frequency changing over time. It can comprehensively capture the interactive behavior of the AC / DC system in transient and dynamic processes, such as the voltage response during power surges and the dynamic process of frequency regulation, providing raw data support for subsequent processing.

[0027] Step S30: Based on the electrical quantity dynamic response data, automatically extract the core indicators used to characterize the interaction characteristics of the AC / DC system.

[0028] It should be noted that the interaction process of AC / DC systems involves dynamic coupling of multiple dimensions such as voltage, frequency, and power. The original data is large and messy, and direct analysis makes it difficult to intuitively judge the quality of the operating status. Therefore, it is necessary to extract core indicators for dimensionality reduction.

[0029] Automatic extraction avoids the subjectivity, inefficiency, and human error inherent in manual extraction, ensuring the consistency and accuracy of extracted indicators. Specifically, the extracted core indicators must accurately reflect the key characteristics of AC / DC system interaction, such as voltage matching degree, frequency response speed, and power coupling strength.

[0030] Step S40: Based on the extracted core indicators, a risk assessment model is constructed to evaluate the operating status of each electrical influence domain, and the risk contribution of each component is calculated based on the risk assessment model to identify the key risk propagation paths within the receiving-end power grid.

[0031] In this embodiment, a risk assessment model is constructed based on the extracted core indicators. This model uses the core indicators as input variables and combines them with constraints such as power grid safety operation standards and equipment rated parameters to quantitatively assess the operational risks existing in the electrical influence domain.

[0032] The calculation of the risk contribution of each component, i.e., the corresponding core indicator, involves quantifying the weight of each indicator's impact on the overall risk, identifying which indicators are the main factors causing the risk. For example, if the risk contribution of a certain core indicator accounts for more than 80%, then the physical link corresponding to that indicator is determined to be the key target for risk control. Identifying key risk propagation paths involves, based on locating key risk sources, combining the power grid topology, such as line connection relationships and node correlation, to trace the main electrical channels through which the risk spreads from the source to the surrounding power grid, providing clear targets for subsequent regulation.

[0033] Step S50: Based on the evaluation results of each of the electrical influence domains, determine the overall integrated operation status of the receiving-end power grid, and generate the coordinated operation control boundary parameters of the flexible DC transmission converter station.

[0034] It should be noted that the assessment results of each electrical influence domain are not simply an summation of results. Instead, it is necessary to consider factors such as the importance of each influence domain (e.g., the weight of load-dense areas and core hub areas is higher), risk level, and correlation of risk propagation paths to comprehensively determine the overall operating status of the receiving-end power grid.

[0035] Specifically, the final output of the evaluation method shown in this embodiment is to generate the coordinated operation control boundary parameters of the flexible DC transmission converter station. These parameters include the power regulation range, voltage control limit, frequency response threshold, etc. of the converter station. Its core function is to provide clear constraints for the operation of the converter station.

[0036] In summary, by generating coordinated control boundary parameters, it is possible to ensure that each converter station can achieve coordinated optimization at the whole network level while taking into account the safe operation of its own region. This avoids the adverse effects of independent control of a single converter station on the power grid in other regions, and ultimately improves the overall safety, stability and operating efficiency of the receiving-end power grid.

[0037] In summary, compared with existing technologies, the receiving-end power grid operation evaluation method based on flexible DC transmission shown in this embodiment has the following advantages: This embodiment constructs an integrated system for receiving-end power grid operation assessment and control adapted to the characteristics of AC / DC hybrid interconnection, effectively addressing the core shortcomings of existing technologies. By dividing independent electrical influence domains based on the flexible DC converter station access point, it achieves refined zonal assessment of power grid operation status, accurately matching the localized characteristics of AC / DC interaction. Based on dynamic response data of electrical quantities, it extracts specific core indicators and constructs a standardized indicator set, comprehensively and accurately characterizing the interaction characteristics of the AC / DC system. Utilizing a risk assessment model covering multiple risk types and considering both direct and indirect contributions of indicators, it significantly improves the accuracy of identifying key risk sources and propagation paths. Finally, by comprehensively assessing the results of each region, it determines the overall state of the power grid and reverse-optimizes the generation of converter station coordinated operation control boundary parameters, forming a closed-loop linkage mechanism of "assessment-control". This scheme significantly improves the accuracy and efficiency of receiving-end power grid operation assessment, effectively enhances the ability to predict and prevent key risks, ensures the safe and stable operation of AC / DC hybrid power grids in multi-converter station access scenarios, and provides reliable technical support for large-scale consumption of new energy and cross-regional power transmission.

[0038] Example 2 The second embodiment of the present invention also provides a method for evaluating the operation of the receiving-end power grid based on flexible DC transmission, which is basically similar to the method shown in the first embodiment, except that: In this embodiment, the step of automatically extracting core indicators for characterizing the interaction characteristics of the AC / DC system based on the dynamic response data of the electrical quantities specifically includes: The collected dynamic response data of electrical quantities are processed in a time-series segmentation manner to filter out the effective data during periods of intense AC / DC power interaction, and simultaneously remove steady-state redundant data and abnormal disturbance noise. Based on the filtered valid data, three core indicators were extracted from the converter station outlet: AC / DC voltage amplitude ratio, frequency response lag time, and reactive power interaction coupling coefficient. These were used to construct a set of interactive characteristic indicators corresponding to the AC / DC system.

[0039] Specifically, the dynamic response data of electrical quantities contains a large amount of redundant information and noise. For example, when the power grid is in steady-state operation, the changes in electrical quantities are gradual, making it difficult to reflect the interaction characteristics of the AC / DC system. This type of data belongs to steady-state redundant data. Furthermore, abnormal disturbance noise caused by measurement equipment errors and transient electromagnetic interference can seriously interfere with the accuracy of core indicators. In this embodiment, through time-series segmentation processing, the original data is divided into several time periods according to the time dimension. By analyzing the power change intensity of each time period, the periods with intense AC / DC power interaction are selected. These periods represent the stages where the interaction characteristics of the AC / DC system are most concentrated and significant, and the corresponding electrical quantity data can truly reflect the dynamic coupling relationship of the system. Simultaneously, steady-state redundant data and abnormal disturbance noise are removed, effectively purifying the data and ensuring that subsequent indicator extraction is based on high-quality, highly relevant, and effective data, thus avoiding evaluation bias caused by data distortion from the source.

[0040] Among them, the three indicators at the converter station outlet—AC / DC voltage amplitude ratio, frequency response lag time, and reactive power interaction coupling coefficient—correspond to three key dimensions of AC / DC system interaction. For example, the AC / DC voltage amplitude ratio directly reflects the degree of voltage matching between the AC and DC sides, and voltage matching is the foundation for the stable operation of the AC / DC system. A ratio that is too large or too small will lead to problems such as decreased converter efficiency and increased voltage fluctuations. The frequency response lag time reflects the timeliness of the converter station's frequency control commands in adjusting the frequency of the receiving-end power grid; an excessively long lag time will lead to decreased frequency stability and difficulty in quickly responding to frequency disturbances. The reactive power interaction coupling coefficient reflects the degree of mutual influence of reactive power in the AC / DC system; excessive reactive power coupling can easily cause risks such as voltage oscillations and reduced stability. In this embodiment, the above three types of indicators are integrated into a set of interaction characteristic indicators corresponding to the AC / DC system, which can more comprehensively and systematically cover the core characteristics of AC / DC system interaction, avoiding the one-sidedness of a single indicator, and providing comprehensive quantitative input for subsequent risk assessment models.

[0041] In this embodiment, the step of extracting three core indicators—AC / DC voltage amplitude ratio, frequency response lag time, and reactive power interaction coupling coefficient—from the filtered valid data to construct a set of interaction characteristic indicators corresponding to the AC / DC system specifically includes: For the AC / DC voltage amplitude ratio index at the converter station outlet, the effective value of AC voltage and the average value of DC voltage at the same time node are extracted from the filtered data, the ratio of the two is calculated and abnormal extreme values ​​are removed, and the time-series average value is taken as the final determined value of the index. The time difference between the issuance of the frequency command at the converter station and the time when the frequency of the key node at the receiving end reaches a stable state is extracted and used as the frequency response lag time. The reactive power interaction coupling coefficient is calculated by analyzing the time-series correlation between active power and reactive power. The three core indicators are standardized and normalized to eliminate the differences in the dimensions of each indicator and integrate them into a unified set of interactive feature indicators corresponding to AC and DC systems.

[0042] It should be noted that when extracting the AC voltage RMS value and DC voltage average value at the same time point from the filtered data, the same time point is a key prerequisite. This ensures that the selected AC voltage and DC voltage data correspond to the same time point, avoiding distortion of the ratio due to time misalignment. The AC voltage RMS value is the standard representation of AC voltage, reflecting the actual work capacity of AC voltage, while the DC voltage average value accurately reflects the stability level of DC voltage. The ratio of the two can objectively reflect the matching relationship between AC and DC voltages.

[0043] In this embodiment, regarding the frequency response lag time, after the converter station issues a frequency control command, the frequency of the key nodes of the receiving-end power grid will not stabilize immediately, and there is a certain response delay. Extracting the time difference between the time when the command is issued and the time when the frequency reaches a stable state can directly quantify the timeliness of frequency regulation. The smaller the value, the faster the frequency control response speed and the stronger the system frequency stability.

[0044] As for the reactive power interaction coupling coefficient, the degree of synchronization between active power and reactive power over time is calculated by analyzing the time-series correlation between them. The stronger the correlation, the tighter the reactive power interaction coupling, and the higher the risk of mutual interference between AC and DC systems during power regulation. This index can accurately quantify the coupling strength of power interaction.

[0045] In this embodiment, the steps of constructing a risk assessment model for evaluating the operating status of each electrical influence domain based on the extracted core indicators, calculating the risk contribution of each component based on the risk assessment model, and identifying the key risk propagation paths within the receiving-end power grid include: Based on the aforementioned core indicators, individual risk indicators corresponding to static voltage over-limit risk, transient power angle instability risk, and converter station overload risk are calculated respectively. Each individual risk indicator is compared with a preset corresponding risk threshold, and a comprehensive risk assessment value for the electrical influence domain is generated through weighted fusion processing. Based on the determination result that the comprehensive risk assessment value exceeds the preset alarm threshold, the contribution of each core indicator to the comprehensive risk assessment value is calculated. The physical links corresponding to the core indicators with the highest contribution are identified as key risk sources within the current electrical influence domain. Based on the power grid topology, the electrical connection paths strongly correlated with the risk sources are traced to identify the key risk propagation paths within the receiving-end power grid.

[0046] It should be noted that the three most common risks during the interaction between flexible DC transmission and the receiving-end power grid include: static voltage exceeding the limit risk (long-term voltage deviation from the rated range will affect the normal operation of electrical equipment and may even cause equipment damage), transient power angle instability risk (after a grid fault, the generator power angle cannot recover to stability, which may lead to system disconnection and large-scale power outages), and converter station overload risk (the converter station's operating power exceeds its rated capacity, which will accelerate equipment aging and may even cause converter valve failure). Based on the core indicators extracted above, a dedicated quantitative calculation model is established for each type of risk. For example, the static voltage exceeding the limit risk is calculated using the voltage amplitude ratio index, and the transient power angle instability risk is calculated using the frequency response lag time, which enables accurate quantification of various risks.

[0047] The preset risk thresholds represent the safety boundaries for various risks, determined comprehensively by power grid safety operation procedures, equipment rated parameters, and engineering experience. When a single risk indicator exceeds the threshold, it indicates that the risk has reached a level requiring attention. In this embodiment, weighted fusion processing assigns different weight coefficients based on the degree of impact of various risks on power grid safety. For example, transient power angle instability risk, which may lead to large-scale power outages, has a higher weight coefficient than static voltage exceeding the limit risk; converter station overload risk directly threatens the safety of core equipment, and its weight coefficient also needs to be carefully considered. Through weighted calculation, a quantitative value of the overall risk level of the electrical influence domain can be obtained, which comprehensively reflects the safety status of the regional power grid.

[0048] In this embodiment, the calculation of the risk contribution of core indicators is essentially a quantification of the impact weight of each core indicator on the comprehensive risk assessment value. For example, if the contribution of a certain core indicator accounts for 80%, it means that the physical link corresponding to the indicator is the main reason for the regional power grid risk exceeding the standard, and subsequent regulation should prioritize targeting this link.

[0049] Finally, the physical components corresponding to the core indicators with the highest contribution are identified as key risk sources. These physical components may be the voltage control module or frequency regulation system of the converter station, or a key line of the power grid. Identifying key risk sources can provide specific operational targets for subsequent regulation.

[0050] Since the power grid topology reflects the interconnections of nodes and lines, analyzing the electrical correlation strength between risk sources and surrounding nodes (such as power flow magnitude and voltage coupling degree) can identify the channels through which risks are most easily spread, i.e., key risk propagation paths. After identifying key risk propagation paths, risk propagation can be blocked by strengthening equipment monitoring along the path and optimizing power flow distribution, thereby achieving the risk management goals of precise prevention and control and source governance.

[0051] In this embodiment, the step of calculating the contribution of each core indicator to the comprehensive risk assessment value based on the determination result that the comprehensive risk assessment value exceeds the preset alarm threshold includes: Calculate the original contribution value of each core indicator in the single risk indicator, and normalize each original contribution value to obtain the normalized contribution factor corresponding to each core indicator. The normalized contribution factor is multiplied by the weight coefficient of the corresponding individual risk indicator to calculate the direct contribution of each core indicator to the comprehensive risk assessment value. Based on the correlation between the core indicators, the indirect contribution caused by their interaction is calculated, and the sum of the direct contribution and the indirect contribution is taken as the final contribution of the core indicators to the comprehensive risk assessment value.

[0052] It should be noted that the original contribution value of each core indicator in the individual risk indicator is a quantitative value obtained by analyzing the correlation between the core indicator and the individual risk indicator (for example, the higher the correlation coefficient between a core indicator and the static voltage limit risk indicator, the greater its original contribution value). Since the magnitude of the original contribution values ​​of different core indicators differs, direct comparison or calculation will lead to distorted results. Therefore, normalization processing is required (mapping the original contribution value to the [0,1] interval) to obtain the normalized contribution factor.

[0053] The aforementioned direct contribution refers to the direct effect of the core indicators themselves on overall risk. It is calculated as the normalized contribution factor multiplied by the weight coefficient of the corresponding individual risk indicator. The normalized contribution factor reflects the degree of influence of the indicator on a single risk, while the weight coefficient of the individual risk reflects the importance of that type of risk in the overall risk. Multiplying the two together accurately quantifies the direct impact of the core indicators on overall risk through specific individual risks.

[0054] For example, if the normalized contribution factor of a certain core indicator to the risk of static voltage exceeding the limit is 0.8, and the weighting coefficient of the risk of static voltage exceeding the limit is 0.3, then the direct contribution of this indicator is 0.8 × 0.3 = 0.24, which intuitively reflects its direct impact.

[0055] Furthermore, in AC / DC systems, core indicators are not independent but exhibit significant correlations. This embodiment calculates indirect contribution based on the correlation between core indicators. Specifically, by analyzing the correlation coefficients between indicators, it quantifies the indirect impact of a particular indicator on overall risk through its influence on other indicators. The final contribution is the sum of direct and indirect contributions, comprehensively and objectively reflecting the overall impact of core indicators on overall risk. This avoids distortion in contribution calculation due to neglecting the coupling relationships between indicators, leading to more accurate identification of key risk sources.

[0056] Specifically, based on the determination that the comprehensive risk assessment value exceeds the preset alarm threshold, the calculation expression for the contribution of each core indicator to the comprehensive risk assessment value is as follows: ; In the formula, C i Core indicators i The final contribution, where n is the total number of core indicators. α i Core indicators i The corresponding normalized contribution factor, w i Core indicators i The corresponding weighting coefficients, λ As an indirect contribution adjustment coefficient, ρ ik Core indicators i With core indicators k The correlation coefficient between them α k Core indicators k The corresponding normalized contribution factor.

[0057] In this embodiment, the steps of determining the overall integrated operating status of the receiving-end power grid and generating the coordinated operation control boundary parameters of the flexible DC transmission converter station by comprehensively considering the evaluation results of each of the electrical influence domains include: Based on the comprehensive risk assessment value of each electrical influence domain and the identified key risk propagation paths, the overall comprehensive operating status score of the receiving-end power grid is calculated using a weighted aggregation method. The overall integrated operation status score is compared with the preset safe operation threshold. When the score is lower than the safe operation threshold, the power and voltage control command boundary parameters of each flexible DC transmission converter station are optimized in reverse according to the degree of influence of each converter station on the key risk propagation path, so as to form a coordinated operation control boundary.

[0058] The comprehensive risk assessment value of each electrical influence domain reflects the risk level of a local area, while the identified key risk propagation paths reflect the potential for risk diffusion. Combining these two aspects provides a more comprehensive representation of the impact of each region on the overall network security. The weight allocation in the weighted aggregation method shown in this embodiment needs to comprehensively consider multiple factors, including: the load density of the electrical influence domain (the denser the load, the higher the weight), the importance level (e.g., hub areas and important user power supply areas have higher weights than ordinary areas), and the correlation of risk propagation paths (the more intersections with risk paths in other areas, the higher the weight). Through weighted aggregation calculation (e.g., overall score = Σ(comprehensive risk assessment value of a region × region weight + path risk level × path weight)), the overall comprehensive operating status score of the receiving-end power grid can be calculated. This score is the core quantitative basis for determining the overall network security level, intuitively reflecting whether the current operating status of the power grid is safe.

[0059] Among them, the preset safe operation threshold is the minimum standard for the safe and stable operation of the power grid. This is usually determined by the power grid planning and design standards, safe operation procedures, etc. When the overall comprehensive operation status score is lower than this threshold, it indicates that there is a global safety risk in the power grid, and control measures need to be initiated immediately.

[0060] Furthermore, based on the degree of influence of each converter station on the critical risk propagation path, that is, by analyzing the impact of each converter station's operating parameters (such as power output and voltage regulation) on the power flow distribution and voltage stability of the critical risk propagation path, the control priority of each converter station is determined (the higher the degree of influence, the higher the control priority). Reverse optimization, on the other hand, aims to reduce the overall risk of the entire network and restore the safe operation of the power grid. It uses optimization algorithms such as genetic algorithms to deduce the operating constraint parameters of the converter stations, ultimately forming the boundary parameters for power and voltage control commands, thus clarifying the operating limits of the converter stations.

[0061] The above parameters constitute the coordinated operation control boundary, which can ensure that each converter station operates within a safe range. At the same time, through mutual coordination, control conflicts are avoided, and ultimately, the risk of the entire network is effectively managed, improving the safety, stability and economic operation of the receiving-end power grid.

[0062] Example 3 Please see Figure 2 The third embodiment of the present invention provides a receiving-end power grid operation evaluation system based on flexible DC transmission, applied to the method described in any of the above embodiments, the system comprising: The electrical zone division module 10 is used to divide the receiving-end power grid into several independent electrical influence domains based on the real-time operating parameters of the receiving-end power grid and the access point of each flexible DC transmission converter station as the division benchmark. The response data acquisition module 20 is used to preset the operation control mode of the flexible DC transmission converter station in each of the electrical influence domains and synchronously acquire the dynamic response data of electrical quantities of key nodes in the electrical influence domains. The core indicator extraction module 30 is used to automatically extract core indicators that characterize the interaction characteristics of AC / DC systems based on the electrical quantity dynamic response data. The risk path identification module 40 is used to construct a risk assessment model for evaluating the operating status of each electrical influence domain based on the extracted core indicators, and to calculate the risk contribution of each component based on the risk assessment model, thereby identifying the key risk propagation path within the receiving-end power grid. The boundary parameter generation module 50 is used to integrate the evaluation results of each of the electrical influence domains, determine the overall integrated operation status of the receiving-end power grid, and generate the coordinated operation control boundary parameters of the flexible DC transmission converter station.

[0063] Compared with existing technologies, the advantages of using the receiving-end power grid operation evaluation system based on flexible DC transmission shown in this embodiment are as follows: This embodiment constructs an integrated system for receiving-end power grid operation assessment and control adapted to the characteristics of AC / DC hybrid interconnection, effectively addressing the core shortcomings of existing technologies. By dividing independent electrical influence domains based on the flexible DC converter station access point, it achieves refined zonal assessment of power grid operation status, accurately matching the localized characteristics of AC / DC interaction. Based on dynamic response data of electrical quantities, it extracts specific core indicators and constructs a standardized indicator set, comprehensively and accurately characterizing the interaction characteristics of the AC / DC system. Utilizing a risk assessment model covering multiple risk types and considering both direct and indirect contributions of indicators, it significantly improves the accuracy of identifying key risk sources and propagation paths. Finally, by comprehensively assessing the results of each region, it determines the overall state of the power grid and reverse-optimizes the generation of converter station coordinated operation control boundary parameters, forming a closed-loop linkage mechanism of "assessment-control". This scheme significantly improves the accuracy and efficiency of receiving-end power grid operation assessment, effectively enhances the ability to predict and prevent key risks, ensures the safe and stable operation of AC / DC hybrid power grids in multi-converter station access scenarios, and provides reliable technical support for large-scale consumption of new energy and cross-regional power transmission.

[0064] Example 4 A fourth embodiment of the present invention provides a readable storage medium having computer instructions stored thereon, which, when executed by a processor, implement the steps of the methods described in the above embodiments.

[0065] Example 5 A fifth embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the methods described in the above embodiments.

[0066] In the description of this specification, 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 invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for evaluating the operation of the receiving-end power grid based on flexible DC transmission, characterized in that, The method includes: Based on the real-time operating parameters of the receiving-end power grid, and taking the access point of each flexible DC transmission converter station as the dividing benchmark, the receiving-end power grid is divided into several independent electrical influence domains. Within each of the aforementioned electrical influence domains, a preset operation control mode for the flexible DC transmission converter station is established, and dynamic response data of electrical quantities of key nodes within the electrical influence domain are collected synchronously. Based on the dynamic response data of electrical quantities, core indicators for characterizing the interaction characteristics of AC / DC systems are automatically extracted. Based on the extracted core indicators, a risk assessment model is constructed to evaluate the operating status of each electrical influence domain, and the risk contribution of each component is calculated based on the risk assessment model to identify the key risk propagation paths within the receiving-end power grid. Based on the assessment results of each of the electrical influence domains, the overall integrated operation status of the receiving-end power grid is determined, and the coordinated operation control boundary parameters of the flexible DC transmission converter station are generated.

2. The method for evaluating the operation of the receiving-end power grid based on flexible DC transmission according to claim 1, characterized in that, The step of automatically extracting core indicators characterizing the interaction characteristics of AC / DC systems based on the dynamic response data of electrical quantities specifically includes: The collected dynamic response data of electrical quantities are processed in a time-series segmentation manner to filter out the effective data during periods of intense AC / DC power interaction, and simultaneously remove steady-state redundant data and abnormal disturbance noise. Based on the filtered valid data, three core indicators were extracted from the converter station outlet: AC / DC voltage amplitude ratio, frequency response lag time, and reactive power interaction coupling coefficient. These were used to construct a set of interactive characteristic indicators for the AC / DC system.

3. The method for evaluating the operation of the receiving-end power grid based on flexible DC transmission according to claim 2, characterized in that, The step of extracting three core indicators—AC / DC voltage amplitude ratio, frequency response lag time, and reactive power interaction coupling coefficient—from the filtered valid data to construct a set of interaction characteristic indicators for the AC / DC system specifically includes: For the AC / DC voltage amplitude ratio index at the converter station outlet, the effective value of AC voltage and the average value of DC voltage at the same time node are extracted from the filtered data, the ratio of the two is calculated and abnormal extreme values ​​are removed, and the time-series average value is taken as the final determined value of the index. The time difference between the issuance of the frequency command at the converter station and the time when the frequency of the key node at the receiving end reaches a stable state is extracted and used as the frequency response lag time. The reactive power interaction coupling coefficient is calculated by analyzing the time-series correlation between active power and reactive power. The three core indicators are standardized and normalized to eliminate the differences in the dimensions of each indicator and integrate them into a unified set of interactive feature indicators corresponding to AC and DC systems.

4. The method for evaluating the operation of the receiving-end power grid based on flexible DC transmission according to claim 1, characterized in that, Based on the extracted core indicators, a risk assessment model is constructed to evaluate the operational status of each electrical influence domain. The steps for calculating the risk contribution of each component based on the risk assessment model and identifying key risk propagation paths within the receiving-end power grid include: Based on the aforementioned core indicators, individual risk indicators corresponding to static voltage over-limit risk, transient power angle instability risk, and converter station overload risk are calculated respectively. Each individual risk indicator is compared with a preset corresponding risk threshold, and a comprehensive risk assessment value for the electrical influence domain is generated through weighted fusion processing. Based on the determination result that the comprehensive risk assessment value exceeds the preset alarm threshold, the contribution of each core indicator to the comprehensive risk assessment value is calculated. The physical links corresponding to the core indicators with the highest contribution are identified as key risk sources within the current electrical influence domain. Based on the power grid topology, the electrical connection paths strongly correlated with the risk sources are traced to identify the key risk propagation paths within the receiving-end power grid.

5. The method for evaluating the operation of the receiving-end power grid based on flexible DC transmission according to claim 4, characterized in that, The steps for calculating the contribution of each core indicator to the comprehensive risk assessment value, based on the determination that the comprehensive risk assessment value exceeds a preset alarm threshold, include: Calculate the original contribution value of each core indicator in the single risk indicator, and normalize each original contribution value to obtain the normalized contribution factor corresponding to each core indicator. The normalized contribution factor is multiplied by the weight coefficient of the corresponding individual risk indicator to calculate the direct contribution of each core indicator to the comprehensive risk assessment value. Based on the correlation between the core indicators, the indirect contribution caused by their interaction is calculated, and the sum of the direct contribution and the indirect contribution is taken as the final contribution of the core indicators to the comprehensive risk assessment value.

6. The method for evaluating the operation of the receiving-end power grid based on flexible DC transmission according to claim 5, characterized in that, Based on the determination that the comprehensive risk assessment value exceeds the preset alarm threshold, the calculation expression for the contribution of each core indicator to the comprehensive risk assessment value is as follows: ； In the formula, C i Core indicators i The final contribution, where n is the total number of core indicators. α i Core indicators i The corresponding normalized contribution factor, w i Core indicators i The corresponding weighting coefficients, λ As an indirect contribution adjustment coefficient, ρ ik Core indicators i With core indicators k The correlation coefficient between them α k Core indicators k The corresponding normalized contribution factor.

7. The method for evaluating the operation of the receiving-end power grid based on flexible DC transmission according to any one of claims 1-6, characterized in that, The steps of determining the overall integrated operating status of the receiving-end power grid based on the assessment results of each of the aforementioned electrical influence domains, and generating the coordinated operation control boundary parameters for the flexible DC transmission converter station, include: Based on the comprehensive risk assessment value of each electrical influence domain and the identified key risk propagation paths, the overall comprehensive operating status score of the receiving-end power grid is calculated using a weighted aggregation method. The overall integrated operation status score is compared with the preset safe operation threshold. When the score is lower than the safe operation threshold, the power and voltage control command boundary parameters of each flexible DC transmission converter station are optimized in reverse according to the degree of influence of each converter station on the key risk propagation path, so as to form a coordinated operation control boundary.

8. A receiving-end power grid operation evaluation system based on flexible DC transmission, characterized in that, The system, applicable to the method of any one of claims 1-7, comprises: The electrical zone division module is used to divide the receiving-end power grid into several independent electrical influence domains based on the real-time operating parameters of the receiving-end power grid and the access point of each flexible DC transmission converter station. The response data acquisition module is used to preset the operation control mode of the flexible DC transmission converter station in each of the electrical influence domains and synchronously acquire the dynamic response data of electrical quantities of key nodes in the electrical influence domains. The core indicator extraction module is used to automatically extract core indicators that characterize the interaction characteristics of AC / DC systems based on the dynamic response data of electrical quantities. The risk path identification module is used to construct a risk assessment model for evaluating the operating status of each electrical influence domain based on the extracted core indicators, and to calculate the risk contribution of each component based on the risk assessment model, thereby identifying the key risk propagation paths within the receiving-end power grid. The boundary parameter generation module is used to integrate the evaluation results of each of the electrical influence domains, determine the overall integrated operation status of the receiving-end power grid, and generate the coordinated operation control boundary parameters of the flexible DC transmission converter station.

9. A readable storage medium having computer instructions stored thereon, characterized in that, When executed by the processor, this instruction implements the steps of the method as described in any one of claims 1-7.

10. An electronic 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 program, it implements the steps of the method as described in any one of claims 1-7.

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