Direct current transmission operation and maintenance analysis method and system based on knowledge graph analysis

Abstract

The invention discloses a direct-current power transmission operation and maintenance analysis method and system based on knowledge graph analysis, and relates to the technical field of power transmission operation and maintenance analysis. The direct-current power transmission operation and maintenance analysis method based on knowledge graph analysis comprises the following steps of performing operation and maintenance analysis on a controller; transformer operation and maintenance analysis; and power transmission line operation and maintenance analysis. The controller operation and maintenance analysis is carried out through the first operation and maintenance data in the power transmission line knowledge graph, whether transformer operation and maintenance analysis is carried out is judged, if the transformer operation and maintenance analysis is carried out, whether power transmission line operation and maintenance analysis is carried out is judged based on the result of the transformer operation and maintenance analysis, and if the power transmission line operation and maintenance analysis is carried out, power transmission line operation and maintenance analysis is carried out. And if yes, judging whether the operation and maintenance analysis of the power transmission line is completed based on the result of the operation and maintenance analysis of the power transmission line, thereby achieving the effect of improving the reliability of the operation and maintenance analysis of the direct-current power transmission line and solving the problem of relevance between the operation and maintenance analysis of the direct-current power transmission line and the power transmission line knowledge graph in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission operation and maintenance analysis, and in particular to a direct current transmission operation and maintenance analysis method and system based on knowledge graph analysis. Background Art

[0002] As the main player in West-to-East Power Transmission, the Ultra-High Voltage Company (EHVCC) has been deeply engaged in the field of DC transmission for many years. From a company with "no technology, no standards, and no experience," it has mastered core DC operation and maintenance technologies, promoted the upgrading of DC transmission technology, and initially established a full lifecycle management system for DC equipment, supported by management specifications, technical specifications, and operational standards. However, with the continuous development of society and the economy, the power load continues to grow, placing increasing demands on transmission systems. Knowledge graphs are a structured knowledge representation method that can efficiently store, manage, and query large amounts of knowledge data. Applying knowledge graph technology to DC transmission operation and maintenance analysis, by combining the emergent capabilities of large models with the interpretability and reliability of knowledge graphs, can improve the diversity and accuracy of decision-making information generated for intelligent DC system status assessment, risk prediction, fault diagnosis, and operation and maintenance analysis, thereby enabling comprehensive equipment analysis and fault warning.

[0003] In the existing technology, by constructing a knowledge graph of the DC transmission system, the entities, attributes and relationships in the acquired operation and maintenance data are structured and represented, and then the knowledge graph analysis technology is used for deep mining and intelligent reasoning to realize the intelligent operation and maintenance of the DC transmission system.

[0004] For example, the patent announcement with announcement number: CN112701711B discloses a method for detecting and evaluating the operation and maintenance safety of important lines in an AC / DC combined converter station, including: establishing a local system equivalent model for the target line to obtain the line impedance index and the through-current safety margin index; performing commutation failure sensitivity and line power transfer detection analysis on the target line to obtain the commutation failure sensitivity index and the line power transfer index; performing overload rate and overload margin, line power deviation, branch sensitivity and line temperature rise detection analysis on the target line to obtain the overload rate and overload margin index, line power deviation index, branch sensitivity index and line temperature rise index; using a fuzzy multi-objective decision-making method to comprehensively consider all the above-mentioned indicators to select the optimal evaluation index at different times to evaluate the importance of the line.

[0005] For example, the invention patent announcement with announcement number: CN113381432B discloses a method for evaluating the impact of synchronous condenser faults on ultra-high voltage direct current transmission, including: establishing a mathematical model of the synchronous condenser; establishing a mathematical model of the ultra-high voltage direct current transmission system; setting a synchronous condenser rotor grounding short-circuit fault; setting a synchronous condenser outlet short-circuit fault; setting a synchronous condenser tripping due to an auxiliary system fault; evaluating the probability of a synchronous condenser commutation failure caused by a rotor grounding short-circuit fault at different degrees, random occurrence times, and different operating conditions; evaluating the probability of a synchronous condenser commutation failure caused by multiple outlet short-circuit faults at different degrees, random occurrence times, and different operating conditions; and evaluating the probability of a synchronous condenser commutation failure caused by a circuit breaker fault between the high-voltage side of the step-up transformer and the busbar.

[0006] However, in the process of implementing the technical solutions of the invention in the embodiments of the present application, the present application found that the above technology has at least the following technical problems:

[0007] In the existing technology, the update of knowledge graphs often fails to fully consider the comprehensiveness of DC transmission line equipment in the operation and maintenance analysis process. For example, the knowledge graph may rely mainly on structured data and ignore key information in unstructured data (such as early signs of equipment aging or the influence of environmental factors). Secondly, static knowledge graphs cannot reflect the dynamic changes of DC transmission status in real time, such as real-time current, temperature or transient data at the time of fault. This will cause delays in fault location on DC transmission lines, leading to incorrect misjudgments. There is a problem of insufficient consideration of the correlation between the operation and maintenance analysis of DC transmission lines and the knowledge graph of transmission lines. Summary of the Invention

[0008] The embodiments of the present application provide a method and system for DC transmission operation and maintenance analysis based on knowledge graph analysis, thereby solving the problem of correlation between the operation and maintenance analysis of DC transmission lines and the knowledge graph of transmission lines in the prior art, and improving the reliability of the operation and maintenance analysis of DC transmission lines.

[0009] An embodiment of the present application provides a direct current transmission operation and maintenance analysis method based on knowledge graph analysis, comprising the following steps: step 1, performing controller operation and maintenance analysis based on first operation and maintenance data in a transmission line knowledge graph, and determining whether to perform transformer operation and maintenance analysis; step 2, if transformer operation and maintenance analysis is performed, determining whether to perform transmission line operation and maintenance analysis based on the result of the transformer operation and maintenance analysis; step 3, if transmission line operation and maintenance analysis is performed, determining whether the transmission line operation and maintenance analysis is completed based on the result of the transmission line operation and maintenance analysis.

[0010] The embodiment of the present application provides a direct current transmission operation and maintenance analysis system based on knowledge graph analysis, including: a controller operation and maintenance analysis module, a transformer operation and maintenance analysis module and a transmission line operation and maintenance analysis module; wherein the controller operation and maintenance analysis module is used to perform controller operation and maintenance analysis based on first operation and maintenance data in the transmission line knowledge graph, and determine whether to perform transformer operation and maintenance analysis; the transformer operation and maintenance analysis module is used to determine whether to perform transmission line operation and maintenance analysis based on the result of the transformer operation and maintenance analysis if the transformer operation and maintenance analysis is performed; the transmission line operation and maintenance analysis module is used to determine whether the transmission line operation and maintenance analysis is completed based on the result of the transmission line operation and maintenance analysis if the transmission line operation and maintenance analysis is performed

[0011] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0012] 1. Perform controller operation and maintenance analysis through the first operation and maintenance data in the transmission line knowledge graph to determine whether to perform transformer operation and maintenance analysis. If transformer operation and maintenance analysis is performed, determine whether to perform transmission line operation and maintenance analysis based on the results of the transformer operation and maintenance analysis. If transmission line operation and maintenance analysis is performed, determine whether the transmission line operation and maintenance analysis is completed based on the results of the transmission line operation and maintenance analysis. This achieves more real-time and effective operation and maintenance analysis of the DC transmission line, thereby improving the reliability of the DC transmission line operation and maintenance analysis, and effectively solves the problem of correlation between the operation and maintenance analysis of the DC transmission line and the transmission line knowledge graph in the existing technology.

[0013] 2. The communication delay weight factor is used to correct the differences between the first and second communication delay times and the communication delay time setting values in the database to obtain the communication delay time impact score. At the same time, the obtained operating temperature impact score, communication delay time impact score, superimposed AC harmonic impact score and DC output voltage impact score are coupled to obtain the controller operation and maintenance analysis index, thereby improving the accuracy of obtaining the controller operation and maintenance analysis index. This will help promote the intelligent and automated level of operation and maintenance management and provide a strong guarantee for the safe and stable operation of the power system.

[0014] 3. The difference between the obtained insulator surface resistivity and the reference insulator surface resistivity in the database is corrected by the insulator surface resistivity weight factor to obtain the insulator surface resistivity influence score. At the same time, the obtained insulator surface resistivity influence coefficient, insulator temperature influence score and first geomagnetic induction current influence score are coupled to obtain the transformer operation and maintenance analysis index, thereby improving the accuracy of transformer operation and maintenance analysis index acquisition, and further realizing the refinement, intelligence and efficiency of transformer operation and maintenance management, thereby improving the reliability and quality of power supply on DC transmission lines.

[0015] 4. By comprehensively considering the controllers, transformers and third-party operation and maintenance data on the DC transmission line that directly reflect the line status, and through weight factor and ratio weighting processing, the impact of various factors on the stability of the DC transmission line is quantitatively evaluated, achieving a comprehensive, accurate and dynamic evaluation of the operation and maintenance status of the DC transmission line, providing strong support for improving operation and maintenance reliability and ensuring stable operation of the line. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A flow chart of a DC transmission operation and maintenance analysis method based on knowledge graph analysis provided in an embodiment of the present application;

[0017] Figure 2 A schematic diagram of the structure of a DC transmission operation and maintenance analysis system based on knowledge graph analysis provided in an embodiment of the present application. DETAILED DESCRIPTION

[0018] The embodiments of the present application solve the problem of correlation between the operation and maintenance analysis of DC transmission lines and the knowledge graph of transmission lines in the prior art by providing a method and system for DC transmission operation and maintenance analysis based on knowledge graph analysis. The method performs controller operation and maintenance analysis through the first operation and maintenance data in the transmission line knowledge graph to obtain controller operation and maintenance analysis indicators, and then determines whether to perform transformer operation and maintenance analysis based on the obtained controller operation and maintenance analysis indicators. If so, the dynamic power distribution state of the transformer is analyzed based on the obtained second operation and maintenance data to obtain transformer operation and maintenance analysis indicators. Finally, based on the obtained transformer operation and maintenance analysis indicators, it is determined whether to perform transmission line operation and maintenance analysis. If so, the method determines whether the transmission line operation and maintenance analysis is completed based on the obtained third operation and maintenance data and in combination with the results of the controller operation and maintenance analysis and the transmission line operation and maintenance analysis, thereby improving the reliability of DC transmission line operation and maintenance analysis.

[0019] The technical solution in the embodiments of the present application is to solve the problem of correlation between the operation and maintenance analysis of the DC transmission line and the transmission line knowledge graph. The overall idea is as follows:

[0020] The controller operation and maintenance analysis is performed through the first operation and maintenance data in the transmission line knowledge graph to determine whether to perform transformer operation and maintenance analysis. If transformer operation and maintenance analysis is performed, whether to perform transmission line operation and maintenance analysis is determined based on the results of the transformer operation and maintenance analysis. If transmission line operation and maintenance analysis is performed, whether the transmission line operation and maintenance analysis is completed is determined based on the results of the transmission line operation and maintenance analysis, thereby achieving the effect of improving the reliability of DC transmission line operation and maintenance analysis.

[0021] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0022] like Figure 1 As shown, it is a flow chart of a DC transmission operation and maintenance analysis method based on knowledge graph analysis provided in an embodiment of the present application. The DC transmission operation and maintenance analysis method based on knowledge graph analysis provided in an embodiment of the present application includes the following steps: step 1, performing controller operation and maintenance analysis based on the first operation and maintenance data in the transmission line knowledge graph to determine whether to perform transformer operation and maintenance analysis; step 2, if transformer operation and maintenance analysis is performed, determining whether to perform transmission line operation and maintenance analysis based on the result of the transformer operation and maintenance analysis; step 3, if transmission line operation and maintenance analysis is performed, determining whether the transmission line operation and maintenance analysis is completed based on the result of the transmission line operation and maintenance analysis.

[0023] In this embodiment, the transmission line knowledge graph is a multi-dimensional, reasonable knowledge network constructed for DC transmission systems. Its core is a heterogeneous graph system formed by device entities as nodes and operation and maintenance relationships as edges. Since direct line operation and maintenance analysis may obscure the true source of the fault, for example, in a ±660kV DC blocking event, initial detection revealed malfunction of the DC transmission line's traveling wave protection. However, tracing back the transmission line knowledge graph revealed that the root cause was a failure in the controller's optoelectronic conversion module, resulting in a loss of trigger pulses, rather than a defect in the line itself. Therefore, this method automatically associates the fault chain of abnormal controller trigger angle, insufficient transformer reactive power compensation, and line harmonic amplification through the knowledge graph. This breaks the information silos between various systems and equipment in traditional operation and maintenance analysis, improves the integrity and comprehensiveness of operation and maintenance analysis, and effectively solves the existing problem of correlation between DC transmission line operation and maintenance analysis and transmission line knowledge graphs. It achieves accurate matching and analysis of operation and maintenance data, providing a strong guarantee for the safe and stable operation of the DC transmission system.

[0024] Furthermore, the specific steps for performing controller operation and maintenance analysis based on the first operation and maintenance data in the transmission line knowledge graph are as follows: A1, obtaining the operating temperature of the DC controller at the current operation and maintenance analysis moment from the constructed transmission line knowledge graph, when the obtained operating temperature is not greater than the operating temperature setting value in the database, executing A2, otherwise prompting the operation and maintenance personnel to increase the cooling fan speed by a preset amplitude; A2, obtaining the superimposed AC harmonics of the DC controller at the corresponding current operation and maintenance analysis moment from the constructed transmission line knowledge graph, when the obtained superimposed AC harmonics are not greater than the superimposed AC harmonics in the database, executing A3, otherwise sending a harmonic suppression instruction, the harmonic suppression instruction including the trigger angle shift instruction and the filter switching number reduction instruction; A3, obtaining the first communication delay time and the second communication delay time of the DC controller at the corresponding current operation and maintenance analysis moment from the constructed transmission line knowledge graph, when the obtained first communication delay time and the second communication delay time When both communication delay times are no greater than the communication delay time setting value in the database, execute A4; otherwise, the operation and maintenance personnel are prompted to inspect the DC controller; A4, obtains the DC output voltage of the DC controller at the current operation and maintenance analysis moment from the constructed transmission line knowledge graph; when the obtained DC output voltage is no greater than the DC output voltage setting value in the database, execute A5; otherwise, send a trigger power reduction instruction; A5, obtains the first operation and maintenance data of the DC controller at the current operation and maintenance analysis moment from the constructed transmission line knowledge graph, and analyzes the interactive control state of the DC controller based on the obtained first operation and maintenance data to obtain the controller operation and maintenance analysis index, the first operation and maintenance data includes operating temperature, superimposed AC harmonics, first communication delay time, second communication delay time and DC output voltage, and the controller operation and maintenance analysis index represents the quantitative data of the influence of the first operation and maintenance data on the interactive control stability of the DC controller.

[0025] In this embodiment, interactive control of the DC controller is the core control mechanism in the DC transmission line, which generally includes two levels: pole control (i.e., pole control level) and valve control (valve group control level). Interactive control enables data exchange and collaborative work between them. The pole control sends control instructions to the valve control, and the valve control generates trigger pulses based on the received control instructions to control the conduction and shutdown of the converter valve. At the same time, the valve control can also feed back the first operation and maintenance data of the DC controller to the pole control, so that the pole control can perform more precise control operations and harmonic suppression.

[0026] The DC controller receives the harmonic suppression instruction and automatically shifts the trigger angle by a preset amplitude, while reducing the number of filter switching times by one. After the preset amplitude trigger angle is shifted back once and the filter switching times are reduced once, the superimposed AC harmonics of the DC controller are reacquired until the reacquired superimposed AC harmonics are no greater than the superimposed AC harmonics in the database. The preset amplitude is usually set to 30°, and the trigger angle is usually between 15° and 165°. Assuming that the interactive control time of the DC controller is set to one hour, the number of filter switching times is usually no more than 5 times within one hour.

[0027] Compared with traditional fixed-trigger-angle control, the harmonic suppression mechanism provided in this example can reduce harmonic distortion by 40%-60%, while reducing filter reactive loss by approximately 35% and improving the DC transmission power factor by 0.8-1.2 percentage points. Through multi-dimensional collaborative optimization, this control strategy achieves a balance between control accuracy and equipment life while ensuring grid power quality. It is particularly suitable for the dynamic harmonic management needs in new energy access scenarios.

[0028] Furthermore, the controller operation and maintenance analysis index is obtained by the following method: the degree of difference between the obtained first communication delay time and the second communication delay time and the communication delay time setting value in the database is corrected by the communication delay time weight factor to obtain the communication delay time impact score; the degree of difference between the obtained operating temperature and the operating temperature setting value in the database is corrected by the operating temperature weight factor to obtain the operating temperature impact score, and the superimposed AC harmonic impact score and the DC output voltage impact score are obtained at the same time; the obtained operating temperature impact score, communication delay time impact score, superimposed AC harmonic impact score and DC output voltage impact score are coupled to obtain the controller operation and maintenance analysis index; the superimposed AC harmonic impact score represents the result of the superimposed AC harmonic weight factor correcting the degree of difference between the obtained superimposed AC harmonic and the superimposed AC harmonic setting value in the database; the DC output voltage impact score represents the result of the DC output voltage weight factor correcting the degree of difference between the obtained DC output voltage and the DC output voltage setting value in the database.

[0029] Among them, the specific restriction expression of the controller operation and maintenance analysis index is:

[0030] YI=YI(1)+YI(2)+YI(3)+YI(4);

[0031] Where YI represents the controller operation and maintenance analysis index of the DC controller at the current operation and maintenance analysis time, YI(1) represents the operating temperature impact score of the DC controller at the current operation and maintenance analysis time, YI(2) represents the communication delay duration impact score of the DC controller at the current operation and maintenance analysis time, YI(3) represents the superimposed AC harmonic impact score of the DC controller at the current operation and maintenance analysis time, and YI(4) represents the DC output voltage impact score of the DC controller at the current operation and maintenance analysis time.

[0032] The specific limiting expression of the operating temperature impact fraction YI(1) is: Where a1 represents the operating temperature weight factor, U1 represents the operating temperature of the DC controller at the current operation and maintenance analysis time, and U0 represents the operating temperature set value.

[0033] The specific limiting expression of the communication delay duration impact fraction YI(2) is: Where a2 represents the communication delay weight factor, H1 represents the first communication delay of the DC controller at the current operation and maintenance analysis time, H2 represents the second communication delay of the DC controller at the current operation and maintenance analysis time, and H0 represents the communication delay setting value.

[0034] The specific limiting expression of the superimposed AC harmonic influence fraction YI(3) is: Where a3 represents the superimposed AC harmonic weight factor, P1 represents the superimposed AC harmonic of the DC controller at the current operation and maintenance analysis time, and P0 represents the superimposed AC harmonic set value.

[0035] The specific limiting expression of the superimposed AC harmonic influence fraction YI(4) is: Where a4 represents the DC output voltage weight factor, Q1 represents the DC output voltage of the DC controller at the current operation and maintenance analysis moment, and Q0 represents the DC output voltage set value.

[0036] In this embodiment, the input devices of the DC controller include but are not limited to a temperature sensor, a timer, a harmonic detection device, and a voltage sensor, wherein the operating temperature is monitored by the temperature sensor, the first communication delay time and the second communication delay time are monitored by the timer, the superimposed AC harmonics are monitored by the harmonic detection device, and the DC output voltage is monitored by the voltage sensor; the first communication delay time represents the communication delay time caused by electromagnetic interference when the valve control of the DC controller receives the phase shift instruction sent by the pole control, and the second communication delay time represents the communication delay time caused by electromagnetic interference when the valve control of the DC controller receives the backup power switching instruction sent by the pole control.

[0037] Among them, the unit of the operating temperature is the same as that of the operating temperature setting value, both are degrees Celsius (℃); the unit of the first communication delay time, the second communication delay time and the communication delay time setting value are the same as that of seconds (s); the unit of the superimposed AC harmonics is the same as that of the superimposed AC harmonics setting value, both are effective values of amperes (A); the unit of the DC output voltage is the same as that of the DC output voltage setting value, both are volts (V).

[0038] The operating temperature set value, communication delay time set value, superimposed AC harmonics set value, and DC output voltage set value are respectively represented by the sum and average of the historical operating temperature, historical communication delay time, historical superimposed AC harmonics, and historical DC output voltage of the DC controller at the time of historical operation and maintenance analysis in the database.

[0039] The database stores preset weight factors that are closely related to the controller operation and maintenance analysis indicators. A pre-defined mapping relationship is established between these weight factors and the corresponding operating temperature impact score, communication delay time impact score, superimposed AC harmonic impact score, and DC output voltage impact score. It is worth noting that this mapping is not set arbitrarily. It can be one-to-one or many-to-one. For example, in practical applications, when it is necessary to evaluate the interactive control stability of the DC controller on the DC transmission line in the knowledge graph, the real-time operating temperature impact score, communication delay time impact score, superimposed AC harmonic impact score, and DC output voltage impact score can be directly input into this preset mapping relationship, so that the communication delay time weight factor, operating temperature weight factor, superimposed AC harmonic weight factor, and DC output voltage weight factor that match the operating temperature impact score, communication delay time impact score, superimposed AC harmonic impact score, and DC output voltage impact score can be obtained quickly and accurately.

[0040] Importantly, to ensure consistency and comparability of the evaluation, the communication delay weighting factor, operating temperature weighting factor, superimposed AC harmonic weighting factor, and DC output voltage weighting factor in this example are all limited to values between 0 and 1, and the sum of the four is 1.

[0041] The aforementioned database is a database for storing various types of setting data established before the design of the DC transmission operation and maintenance analysis method based on knowledge graph analysis. The database includes but is not limited to preset controller operation and maintenance analysis indicators, preset transformer operation and maintenance analysis indicators, preset transmission line operation and maintenance analysis indicators and current operation and maintenance analysis moments. Various numerical values therein are directly set by technical personnel. Among them, the setting basis of the preset controller operation and maintenance analysis indicators can be determined according to the actual application scenario of the DC controller on the DC transmission line. For example, the preset controller operation and maintenance analysis indicators are represented by the sum and average of the historical controller operation and maintenance analysis indicators of the DC controller in the knowledge graph in the database at the historical operation and maintenance analysis moments. In addition, various numerical values in the database can be set and fine-tuned by technical personnel according to actual debugging.

[0042] It should be understood that the controller operation and maintenance analysis indicators increase with the increase of operating temperature, first communication delay time, second communication delay time, superimposed AC harmonics and DC output voltage. Among them, when the first communication delay increases, the standard deviation of the arrival time distribution of the control instruction may increase, forcing the second communication delay to add additional buffer time to maintain system stability; when the superimposed AC harmonics increase, the probability of the DC controller failing to commutate or shift phases increases, which causes voltage ripples in the converter trigger angle, thereby increasing the DC voltage fluctuation amplitude.

[0043] By considering the above-mentioned influencing mechanisms, it is helpful to transform the discrete operation and maintenance data in the transmission line knowledge graph into a physically meaningful association network, effectively solving the "data island" and "mechanism loss" problems existing in traditional methods, and shifting the operation and maintenance analysis of the DC transmission system from experience-driven to knowledge-driven, thereby improving the reliability of the DC transmission line operation and maintenance analysis.

[0044] Furthermore, the specific process for determining whether to perform transformer operation and maintenance analysis is as follows: when the obtained controller operation and maintenance analysis index is not greater than the controller operation and maintenance analysis index preset in the database, the controller operation and maintenance analysis is completed and the transformer operation and maintenance analysis instruction is sent, otherwise harmonic interference correction is performed; harmonic interference correction is used to trigger the pulse phase adjustment mechanism of the DC controller and inject the reverse harmonic current of the mapping deviation into the control circuit of the DC controller; the mapping deviation represents the result of mapping the obtained controller operation and maintenance analysis index deviation with the harmonic current deviation in the database; the reverse harmonic current represents a current that is opposite in direction and equal in magnitude to the harmonic current of the control circuit in the DC controller at the current operation and maintenance analysis moment.

[0045] In this embodiment, the controller operation and maintenance analysis indicator deviation represents the difference between the preset controller operation and maintenance analysis indicator and the obtained controller operation and maintenance analysis indicator. Harmonic interference correction can be automatically performed through the pulse phase adjustment module built into the DC controller and the active harmonic compensation device. This not only solves the problem of real-time control of harmonic interference, but also promotes the paradigm shift of DC transmission operation and maintenance from "periodic maintenance" to "predictive maintenance", which is of significant value in improving the resilience of the power grid in new energy grid-connected scenarios.

[0046] Furthermore, the specific steps of transformer operation and maintenance analysis are as follows: B1, real-time monitoring of the dynamic power distribution process of the transformer through the constructed transmission line knowledge graph, and at the same time judging the memory overflow value of the edge node algorithm in the transmission line knowledge graph at the current operation and maintenance analysis moment. When the obtained memory overflow value is not greater than the reference memory overflow value in the database, B2 is executed, otherwise the operation and maintenance personnel are prompted to optimize the program memory corresponding to the edge node algorithm in the transmission line knowledge graph (such as partitioning or slicing the corresponding program memory to reduce the memory pressure of a single node in the transmission line knowledge graph); B2, obtaining the second operation and maintenance data of the transformer corresponding to the current operation and maintenance analysis moment, the second operation and maintenance data including ambient humidity, insulator surface resistivity, insulator temperature and the first geomagnetic induction current, the first geomagnetic induction current is used to reflect the degree of electromagnetic interference of the transformer at the current operation and maintenance analysis moment; B3, analyzing the dynamic power distribution state of the transformer based on the obtained second operation and maintenance data, and obtaining the transformer operation and maintenance analysis index, the transformer operation and maintenance analysis index represents the quantitative data of the influence of the second operation and maintenance data on the insulation performance of the transformer.

[0047] In this embodiment, the memory usage data of the edge node algorithm (including memory overflow values) is collected in real time through a distributed memory monitoring component (such as Prometheus+Grafana) integrated in the transmission line knowledge graph. The ambient humidity is monitored by a capacitive humidity sensor, the surface resistivity of the insulator is monitored by a four-probe high resistance meter, the insulator temperature is monitored by an infrared thermal imager, and the geomagnetic induction current (including the first geomagnetic induction current and the second geomagnetic induction current) is monitored by a fluxgate sensor. This realizes a complete closed loop from the collection of the second operation and maintenance data to intelligent decision-making, thereby improving the accuracy and reliability of the transformer insulation performance evaluation on the DC transmission line.

[0048] Furthermore, the transformer operation and maintenance analysis index is obtained by the following method: the degree of difference between the obtained insulator surface resistivity and the reference insulator surface resistivity in the database is corrected by the insulator surface resistivity weight factor to obtain the insulator surface resistivity influence score; the degree of influence of the obtained ambient humidity on the insulator surface resistivity at the current operation and maintenance analysis moment is analyzed to obtain the insulator surface resistivity influence coefficient, and the insulator surface resistivity influence coefficient is used to quantify the degree of influence of the ambient humidity on the insulator surface resistivity of the transformer at the current operation and maintenance analysis moment; the degree of difference between the obtained insulator temperature and the insulator temperature setting value in the database is corrected by the insulator temperature weight factor to obtain the insulator temperature influence score; the degree of difference between the obtained first geomagnetic induction current and the first geomagnetic induction current setting value in the database is corrected by the first geomagnetic induction current weight factor to obtain the first geomagnetic induction current influence score; the obtained insulator surface resistivity influence coefficient, the insulator temperature influence score and the first geomagnetic induction current influence score are coupled to obtain the transformer operation and maintenance analysis index.

[0049] The insulator surface resistivity influence coefficient represents the result of correlation processing between the obtained environmental humidity coefficient and the insulator surface resistivity influence score, and the environmental humidity coefficient represents the ratio of the obtained environmental humidity to the environmental humidity set value in the database.

[0050] When the obtained controller operation and maintenance analysis index is not greater than the controller operation and maintenance analysis index preset in the database, the specific restriction expression of the transformer operation and maintenance analysis index is:

[0051] ER=ER(1)+ER(2)+ER(3),N1≤N0;

[0052] Wherein, ER represents the transformer operation and maintenance analysis index at the current operation and maintenance analysis moment, ER(1) represents the insulator surface resistivity influence coefficient of the transformer at the current operation and maintenance analysis moment, ER(2) represents the insulator temperature influence score of the transformer at the corresponding current operation and maintenance analysis moment, ER(3) represents the first geomagnetic induction current influence score of the transformer at the corresponding current operation and maintenance analysis moment, N1 represents the memory overflow value of the edge node algorithm in the transmission line knowledge graph at the current operation and maintenance analysis moment, and N0 represents the reference memory overflow value.

[0053] The specific limiting expression of the insulator surface resistivity influence coefficient ER(1) is: ER(1) = S*Z, Where S represents the ambient humidity coefficient of the transformer at the current operation and maintenance analysis time, Z represents the insulator surface resistivity impact score of the transformer at the current operation and maintenance analysis time, S1 represents the ambient humidity of the transformer at the current operation and maintenance analysis time, S0 represents the ambient humidity setting value, b1 represents the insulator surface resistivity weight factor, Z1 represents the insulator surface resistivity of the transformer at the current operation and maintenance analysis time, and Z0 represents the insulator surface resistivity setting value.

[0054] The specific limiting expression of the insulator temperature influence fraction ER(2) is: Where R1 represents the insulator temperature of the transformer at the current operation and maintenance analysis time, R0 represents the insulator temperature setting value, and b2 represents the insulator temperature weight factor.

[0055] The specific limiting expression of the first geomagnetic induction current influence fraction ER(3) is: Wherein, V1 represents the first geomagnetic induction current of the transformer at the current operation and maintenance analysis moment, V0 represents the set value of the first geomagnetic induction current, and b3 represents the weight factor of the first geomagnetic induction current.

[0056] In this embodiment, the units of ambient humidity and the ambient humidity setting value are the same, both are relative humidity percentage (%RH), the units of the insulator surface resistivity and the insulator surface resistivity setting value are the same, both are megaohm·cm (MΩ·cm), the units of the insulator temperature and the insulator temperature setting value are the same, both are degrees Celsius (°C), and the units of the geomagnetic induced current and the geomagnetic induced current setting value (including the first geomagnetic induced current setting value and the second geomagnetic induced current setting value) are the same, both are amperes (A); the ambient humidity setting value, the insulator surface resistivity setting value, the insulator temperature setting value, and the first geomagnetic induced current setting value are respectively represented by the sum and average of the historical ambient humidity, historical insulator surface resistivity, historical insulator temperature, and historical first geomagnetic induced current of the transformer at the time of historical operation and maintenance analysis in the database.

[0057] The insulator surface resistivity weight factor, the insulator temperature weight factor, and the first geomagnetic induction current weight factor are respectively the influence of the insulator surface resistivity, the insulator temperature, and the first geomagnetic induction current, which are preset in the database, on the transformer operation and maintenance analysis process. Specifically, the database stores preset weight factors corresponding to the insulator surface resistivity, the insulator temperature, and the first geomagnetic induction current. There is a pre-set mapping relationship between these weight factors and the insulator surface resistivity, the insulator temperature, and the first geomagnetic induction current. This mapping relationship can be one-to-one or many-to-one. For example, in actual applications, the real-time insulator surface resistivity, the insulator temperature, and the first geomagnetic induction current can be input into this mapping relationship to quickly obtain the corresponding weight factors.

[0058] In this example, the insulator surface resistivity weighting factor, the insulator temperature weighting factor, and the first geomagnetic induction current weighting factor generally range from 0 to 1, and the sum of the three is 1.

[0059] It should be understood that the transformer operation and maintenance analysis indicators increase with the increase of ambient humidity, insulator temperature and the first geomagnetic induced current, and the transformer operation and maintenance analysis indicators decrease with the increase of the insulator surface resistivity. Among them, the decrease in resistivity may lead to an increase in leakage current, thereby generating more heat and increasing the temperature. The temperature change may affect the conductivity of the insulator material, forming a feedback loop. In addition, the change in resistivity may affect the geomagnetic induced current, because the change in the conductivity of the insulator material will affect the distribution of the electromagnetic field, and thus affect the magnitude of the induced current.

[0060] By considering the above-mentioned influencing mechanisms, it is helpful to analyze the multi-dimensional influencing paths of the surface resistivity of transformer insulators, optimize the power distribution of transformers, effectively solve the technical problem of insufficient multi-parameter coupling analysis in traditional operation and maintenance, and thus achieve improved reliability of DC transmission line operation and maintenance analysis.

[0061] Furthermore, the specific process for determining whether to conduct transmission line operation and maintenance analysis is as follows: determining whether the obtained transformer operation and maintenance analysis index is not greater than the transformer operation and maintenance analysis index preset in the database: if the obtained transformer operation and maintenance analysis index is not greater than the transformer operation and maintenance analysis index preset in the database, then completing the transformer operation and maintenance analysis and sending the transmission line operation and maintenance analysis instruction, and at the same time, based on the obtained transformer operation and maintenance analysis index, performing local reconstruction of the transformer nodes whose states have changed in the transmission line knowledge graph; if the obtained transformer operation and maintenance analysis index is greater than the transformer operation and maintenance analysis index preset in the database, then updating the pollution level threshold of the corresponding insulator of the transformer based on the obtained transformer operation and maintenance analysis index deviation.

[0062] In this embodiment, the transformer operation and maintenance analysis indicator deviation represents the difference between the preset transformer operation and maintenance analysis indicator and the obtained transformer operation and maintenance analysis indicator. The preset transformer operation and maintenance analysis indicator is represented by the sum and average of the historical transformer operation and maintenance analysis indicators of the transformers in the database at the historical operation and maintenance analysis moments. The local reconstruction is automatically performed through a program preset in the transmission line knowledge graph. The contamination level threshold is used to reflect the degree of contamination of the transformer insulator, thereby realizing closed-loop management of transformer operation and maintenance.

[0063] Furthermore, the specific process of judging whether the transmission line operation and maintenance analysis is completed based on the results of the transmission line operation and maintenance analysis is as follows: when the obtained transmission line operation and maintenance analysis index is not greater than the transmission line operation and maintenance analysis index preset in the database, the transmission line operation and maintenance analysis is completed and a fault location instruction is sent. At the same time, the operation and maintenance strategy is formulated and optimized based on the results of the fault location. Otherwise, the DC power setting value of the transformer is adjusted based on the deviation of the obtained transmission line operation and maintenance analysis index; the DC power setting value is used to adjust the operating status of the DC transmission line where the transformer is located.

[0064] In this embodiment, the DC power setting value is the initial setting value of the transformer, which is set by a preset personnel. The adjustment range of the DC power setting value is obtained by mapping the obtained transmission line operation and maintenance analysis indicator deviation in the database. The transmission line operation and maintenance analysis indicator deviation represents the difference between the preset transmission line operation and maintenance analysis indicator and the obtained transmission line operation and maintenance analysis indicator. The preset transmission line operation and maintenance analysis indicator is represented by the sum and average of the historical transmission line operation and maintenance analysis indicators of the DC transmission lines in the database at the historical operation and maintenance analysis moments. When the obtained transmission line operation and maintenance analysis indicator is not greater than the transmission line operation and maintenance analysis indicator preset in the database, it indicates that the DC transmission line at the corresponding operation and maintenance analysis moment is operating stably. At this time, the subsequent steps of the subsequent transmission line knowledge graph (such as fault location) can be executed, thereby realizing closed-loop management of the DC transmission line operation and maintenance analysis.

[0065] Furthermore, the transmission line operation and maintenance analysis index is obtained by the following method: the obtained controller operation and maintenance analysis index is corrected by the controller operation and maintenance analysis index weight factor to obtain the controller operation and maintenance analysis index influence score, and the obtained transformer operation and maintenance analysis index is corrected by the transformer operation and maintenance analysis index weight factor to obtain the transformer operation and maintenance analysis index influence score; the obtained first operation and maintenance data and the second operation and maintenance data are input into the transmission line knowledge graph, and the third operation and maintenance data of the DC transmission line at the current operation and maintenance analysis moment is obtained, and the obtained third operation and maintenance data are respectively weighted by the corresponding third operation and maintenance data set value in the database to obtain the conductor vibration amplitude influence score, the conductor transmission temperature influence score and the second geomagnetic induction current influence score; the obtained conductor vibration amplitude influence score, the conductor transmission temperature influence score and the second geomagnetic induction current influence score are coupled to obtain the transmission line operation and maintenance analysis index influence score, and the obtained controller operation and maintenance analysis index influence score, the transformer operation and maintenance analysis index influence score and the transmission line operation and maintenance analysis index influence score are coupled to obtain the transmission line operation and maintenance analysis index.

[0066] Among them, the third operation and maintenance data includes the conductor vibration amplitude, the conductor transmission temperature and the second geomagnetic induction current; the conductor vibration amplitude influence score represents the result of the conductor vibration amplitude weight factor correcting the difference between the obtained conductor vibration amplitude and the conductor vibration amplitude set value in the database; the conductor transmission temperature influence score represents the result of the conductor transmission temperature weight factor correcting the difference between the obtained conductor transmission temperature and the conductor transmission temperature set value in the database; the second geomagnetic induction current influence score represents the result of the second geomagnetic induction current weight factor correcting the difference between the obtained second geomagnetic induction current and the second geomagnetic induction current set value in the database; the transmission line operation and maintenance analysis index influence score represents the quantitative data of the influence of the third operation and maintenance data on the stability of the DC transmission line; the transmission line operation and maintenance analysis index represents the quantitative data of the influence of the controller operation and maintenance analysis index, the transformer operation and maintenance analysis index and the third operation and maintenance data on the stability of the DC transmission line.

[0067] Specifically, when the obtained transformer operation and maintenance analysis index is not greater than the transformer operation and maintenance analysis index preset in the database, the specific restriction expression of the transmission line operation and maintenance analysis index is:

[0068] SAN=SAN(1)+SAN(2)+SAN(3);

[0069] Where SAN represents the transmission line operation and maintenance analysis index of the DC transmission line at the current operation and maintenance analysis moment, SAN(1) represents the influence score of the controller operation and maintenance analysis index of the DC transmission line at the current operation and maintenance analysis moment, SAN(2) represents the influence score of the transformer operation and maintenance analysis index of the DC transmission line at the corresponding current operation and maintenance analysis moment, and SAN(3) represents the influence score of the transmission line operation and maintenance analysis index of the DC transmission line at the corresponding current operation and maintenance analysis moment.

[0070] The specific restricted expression of the controller operation and maintenance analysis index influence score SAN(1) is: SAN(1) = d1*YI, where d1 represents the controller operation and maintenance analysis index weight factor, and YI represents the controller operation and maintenance analysis index of the DC controller at the current operation and maintenance analysis moment.

[0071] The specific restricted expression of the transformer operation and maintenance analysis index influence score SAN(2) is: SAN(2) = d2*ER, where d2 represents the transformer operation and maintenance analysis index weight factor, and ER represents the transformer operation and maintenance analysis index of the transformer at the current operation and maintenance analysis moment.

[0072] The specific restricted expression of the transmission line operation and maintenance analysis index impact score SAN(3) is: SAN(3) = L1 + L2 + L3, Wherein, L1 represents the influence score of the conductor vibration amplitude of the DC transmission line at the current operation and maintenance analysis time, L2 represents the influence score of the conductor transmission temperature of the DC transmission line at the current operation and maintenance analysis time, L3 represents the influence score of the second geomagnetic induction current of the DC transmission line at the current operation and maintenance analysis time, d3 represents the conductor vibration amplitude weighting factor, L11 represents the conductor vibration amplitude of the DC transmission line at the current operation and maintenance analysis time, L10 represents the conductor vibration amplitude setting value, d4 represents the conductor transmission temperature weighting factor, L22 represents the conductor transmission temperature of the DC transmission line at the current operation and maintenance analysis time, L20 represents the conductor transmission temperature setting value, d5 represents the second geomagnetic induction current weighting factor, L33 represents the second geomagnetic induction current of the DC transmission line at the current operation and maintenance analysis time, and L30 represents the second geomagnetic induction current setting value.

[0073] In this embodiment, the units of the conductor vibration amplitude and the conductor vibration amplitude setting value are the same, both in millimeters (mm); the units of the conductor transmission temperature and the conductor transmission temperature setting value are the same, both in degrees Celsius (°C); the conductor vibration amplitude is obtained by monitoring an accelerometer, and the conductor transmission temperature is obtained by monitoring an infrared thermal imager; the conductor vibration amplitude setting value, the conductor transmission temperature setting value, and the second geomagnetic induction current setting value are respectively represented by the sum and average of historical transmission line operation and maintenance analysis indicators of the direct current transmission lines in the database at the time of historical operation and maintenance analysis.

[0074] The controller operation and maintenance analysis indicator weight factor, transformer operation and maintenance analysis indicator weight factor, conductor vibration amplitude weight factor, conductor transmission temperature weight factor, and second geomagnetic induction current weight factor are respectively the influence degrees of the controller operation and maintenance analysis indicator, transformer operation and maintenance analysis indicator, conductor vibration amplitude, conductor transmission temperature, and second geomagnetic induction current, which are preset in the database, on the operation and maintenance analysis process of the DC transmission line. Specifically, the database stores preset weight factors corresponding to the controller operation and maintenance analysis indicator, transformer operation and maintenance analysis indicator, conductor vibration amplitude, conductor transmission temperature, and second geomagnetic induction current. There is a pre-set mapping relationship between these weight factors and the controller operation and maintenance analysis indicator, transformer operation and maintenance analysis indicator, conductor vibration amplitude, conductor transmission temperature, and second geomagnetic induction current. This mapping relationship can be one-to-one or many-to-one. For example, in actual applications, the real-time controller operation and maintenance analysis indicator, transformer operation and maintenance analysis indicator, conductor vibration amplitude, conductor transmission temperature, and second geomagnetic induction current can be input into this mapping relationship to quickly obtain the corresponding weight factors.

[0075] In this example, the controller operation and maintenance analysis index weight factor, transformer operation and maintenance analysis index weight factor, conductor vibration amplitude weight factor, conductor transmission temperature weight factor, and second geomagnetic induction current weight factor typically range from 0 to 1, and the sum of the five is 1.

[0076] It should be understood that the transmission line operation and maintenance analysis index increases with the increase of the controller operation and maintenance analysis index influence score, the transformer operation and maintenance analysis index influence score and the transmission line operation and maintenance analysis index influence score. Among them, the transmission line operation and maintenance analysis index influence score increases with the increase of the conductor vibration amplitude, the conductor transmission temperature and the second geomagnetic induction current.

[0077] When the controller operation and maintenance analysis index increases, the corresponding controller performance decreases. At this time, the control accuracy of the converter valve trigger angle decreases, which increases the DC voltage fluctuation, thereby causing the harmonic content of the transmission line to increase and the risk of DC transmission line overload.

[0078] When the transformer operation and maintenance analysis index increases, the corresponding transformer DC bias magnetization occurs. At this time, the excitation current is distorted, which increases the reactive power consumption of the converter station, thereby causing a decrease in the voltage stability of the transmission line, the hot spot temperature of the transformer winding, and the power supply reliability of the DC transmission line.

[0079] When the second geomagnetic induction current increases, the corresponding wire temperature rises. At this time, the difference in thermal expansion coefficient causes the wire tension to change, which in turn leads to an increase in the fluctuation degree of the electromagnetic force of the wire and the coupling of the vibration frequency.

[0080] By considering the above-mentioned influencing mechanisms, the problems of isolated indicators and lack of correlation in traditional methods are effectively solved, providing theoretical support and technical implementation paths for improving the reliability of DC transmission systems, thereby achieving improved reliability in DC transmission line operation and maintenance analysis.

[0081] like Figure 2 As shown, it is a structural schematic diagram of a DC transmission operation and maintenance analysis system based on knowledge graph analysis provided in an embodiment of the present application. The DC transmission operation and maintenance analysis system based on knowledge graph analysis provided in an embodiment of the present application includes: a controller operation and maintenance analysis module, a transformer operation and maintenance analysis module and a transmission line operation and maintenance analysis module; wherein, the controller operation and maintenance analysis module is used to perform controller operation and maintenance analysis based on the first operation and maintenance data in the transmission line knowledge graph, and determine whether to perform transformer operation and maintenance analysis; the transformer operation and maintenance analysis module is used to determine whether to perform transmission line operation and maintenance analysis based on the result of the transformer operation and maintenance analysis if the transformer operation and maintenance analysis is performed; the transmission line operation and maintenance analysis module is used to determine whether the transmission line operation and maintenance analysis is completed based on the result of the transmission line operation and maintenance analysis if the transmission line operation and maintenance analysis is performed.

[0082] In this embodiment, a progressive analysis process from controller to transformer to transmission line is implemented, as well as collaborative work among the controller operation and maintenance analysis module, transformer operation and maintenance analysis module, and transmission line operation and maintenance analysis module to dynamically track the fault impact path. For example, when the controller trigger angle is abnormal, the system automatically associates it with the transformer reactive power compensation status and predicts the risk of excessive line harmonics. This not only improves the reliability of the DC transmission system, but also provides key technical support for building an autonomous operation and maintenance system for the smart grid.

[0083] To summarize, the embodiment of the present application performs controller operation and maintenance analysis through the first operation and maintenance data in the transmission line knowledge graph to determine whether to perform transformer operation and maintenance analysis. If transformer operation and maintenance analysis is performed, whether to perform transmission line operation and maintenance analysis is determined based on the results of the transformer operation and maintenance analysis. If transmission line operation and maintenance analysis is performed, whether the transmission line operation and maintenance analysis is completed is determined based on the results of the transmission line operation and maintenance analysis, thereby achieving more real-time and more effective operation and maintenance analysis of the DC transmission line, and further improving the reliability of the DC transmission line operation and maintenance analysis, effectively solving the problem of correlation between the operation and maintenance analysis of the DC transmission line and the transmission line knowledge graph in the prior art.

[0084] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0085] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts 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, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0086] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0087] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0088] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0089] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A DC transmission operation and maintenance analysis method based on knowledge graph analysis, characterized in that: The following steps are involved: Step 1: Perform controller operation and maintenance analysis based on the first operation and maintenance data in the transmission line knowledge graph to determine whether to perform transformer operation and maintenance analysis; Step 2: If transformer operation and maintenance analysis is performed, determine whether to perform transmission line operation and maintenance analysis based on the results of the transformer operation and maintenance analysis; Step three: if the transmission line operation and maintenance analysis is performed, whether the transmission line operation and maintenance analysis is completed is determined based on the result of the transmission line operation and maintenance analysis.

2. The method for DC transmission operation and maintenance analysis based on knowledge graph analysis according to claim 1, characterized in that: The specific steps of performing controller operation and maintenance analysis based on the first operation and maintenance data in the transmission line knowledge graph are: A1: Obtain the operating temperature of the DC controller at the current operation and maintenance analysis time from the constructed transmission line knowledge graph. If the obtained operating temperature is not greater than the operating temperature setting value in the database, execute A2; otherwise, prompt the operation and maintenance personnel to increase the cooling fan speed by a preset range. A2: Obtain the superimposed AC harmonics of the DC controller at the current operation and maintenance analysis time from the constructed transmission line knowledge graph. If the superimposed AC harmonics obtained are not greater than the superimposed AC harmonics in the database, execute A3; otherwise, send a harmonic suppression instruction, which includes a trigger angle shift instruction and a filter switching frequency reduction instruction. A3: Obtain the first communication delay and second communication delay of the DC controller at the current operation and maintenance analysis time from the constructed transmission line knowledge graph. If both the obtained first communication delay and second communication delay are not greater than the communication delay setting value in the database, execute A4; otherwise, prompt the operation and maintenance personnel to inspect the DC controller. A4: Obtain the DC output voltage of the DC controller at the current operation and maintenance analysis time from the constructed transmission line knowledge graph. If the obtained DC output voltage is not greater than the DC output voltage set value in the database, execute A5; otherwise, send a trigger power reduction instruction; A5. Obtain first operation and maintenance data of the DC controller at the current operation and maintenance analysis moment from the constructed transmission line knowledge graph. Simultaneously, analyze the interactive control state of the DC controller based on the obtained first operation and maintenance data to obtain a controller operation and maintenance analysis indicator. The first operation and maintenance data includes operating temperature, superimposed AC harmonics, first communication delay duration, second communication delay duration, and DC output voltage. The controller operation and maintenance analysis indicator represents quantitative data of the degree of influence of the first operation and maintenance data on the interactive control stability of the DC controller.

3. The method for DC transmission operation and maintenance analysis based on knowledge graph analysis according to claim 2, characterized in that: The controller operation and maintenance analysis indicators are obtained by the following method: Correcting the differences between the first and second communication delay times and the communication delay time setting values in the database using a communication delay time weight factor to obtain a communication delay time impact score; The difference between the obtained operating temperature and the operating temperature set value in the database is corrected by the operating temperature weight factor to obtain the operating temperature impact score, and the superimposed AC harmonic impact score and the DC output voltage impact score are also obtained; The obtained operating temperature impact score, communication delay impact score, superimposed AC harmonic impact score, and DC output voltage impact score are coupled to obtain the controller operation and maintenance analysis index; The superimposed AC harmonics influence score represents the result of the superimposed AC harmonics weight factor correcting the difference between the acquired superimposed AC harmonics and the superimposed AC harmonics set value in the database; The DC output voltage impact score represents a result of the DC output voltage weight factor correcting the degree of difference between the acquired DC output voltage and the DC output voltage set value in the database.

4. The method for DC transmission operation and maintenance analysis based on knowledge graph analysis according to claim 2, characterized in that: The specific process of determining whether to perform transformer operation and maintenance analysis is as follows: When the obtained controller operation and maintenance analysis index is not greater than the controller operation and maintenance analysis index preset in the database, the controller operation and maintenance analysis is completed and the transformer operation and maintenance analysis instruction is sent; otherwise, harmonic interference correction is performed; The harmonic interference correction is used to trigger the pulse phase adjustment mechanism of the DC controller and inject the reverse harmonic current of the mapping deviation into the control circuit of the DC controller; The mapping deviation represents the result of mapping the obtained controller operation and maintenance analysis indicator deviation with the harmonic current deviation in the database; The reverse harmonic current represents a current having a direction opposite to and a magnitude equal to the harmonic current of the control circuit in the DC controller at the current operation and maintenance analysis moment.

5. The method for DC transmission operation and maintenance analysis based on knowledge graph analysis according to claim 1, characterized in that: The specific steps of the transformer operation and maintenance analysis are: B1: Monitor the dynamic power distribution process of the transformer in real time through the constructed transmission line knowledge graph. If the obtained memory overflow value is not greater than the reference memory overflow value in the database, execute B2. Otherwise, prompt the operation and maintenance personnel to optimize the program memory corresponding to the edge node algorithm in the transmission line knowledge graph. B2, obtaining second operation and maintenance data of the transformer corresponding to the current operation and maintenance analysis time, where the second operation and maintenance data includes ambient humidity, insulator surface resistivity, insulator temperature, and a first geomagnetic induction current, where the first geomagnetic induction current is used to reflect the degree of electromagnetic interference of the transformer at the current operation and maintenance analysis time; B3. Analyze the dynamic power distribution state of the transformer based on the acquired second operation and maintenance data to obtain a transformer operation and maintenance analysis index, where the transformer operation and maintenance analysis index represents quantitative data of the degree of influence of the second operation and maintenance data on the insulation performance of the transformer.

6. A method for DC transmission operation and maintenance analysis based on knowledge graph analysis as claimed in claim 5, characterized in that: The transformer operation and maintenance analysis indicators are obtained by the following method: The difference between the obtained insulator surface resistivity and the reference insulator surface resistivity in the database is corrected by using the insulator surface resistivity weight factor to obtain the insulator surface resistivity influence score; Analyze the influence of the acquired ambient humidity on the surface resistivity of the insulator at the current operation and maintenance analysis time to obtain an insulator surface resistivity influence coefficient, wherein the insulator surface resistivity influence coefficient is used to quantify the influence of the ambient humidity on the surface resistivity of the transformer insulator at the current operation and maintenance analysis time; The difference between the obtained insulator temperature and the insulator temperature setting value in the database is corrected by the insulator temperature weight factor to obtain the insulator temperature impact score; Correcting the difference between the acquired first geomagnetic induction current and the first geomagnetic induction current set value in the database using the first geomagnetic induction current weight factor to obtain a first geomagnetic induction current influence score; The obtained insulator surface resistivity influence coefficient, insulator temperature influence score and first geomagnetic induction current influence score are coupled to obtain the transformer operation and maintenance analysis index.

7. The method for DC transmission operation and maintenance analysis based on knowledge graph analysis according to claim 5, characterized in that: The specific process of determining whether to perform transmission line operation and maintenance analysis is as follows: If the obtained transformer operation and maintenance analysis index is not greater than the transformer operation and maintenance analysis index preset in the database, the transformer operation and maintenance analysis is completed and the transmission line operation and maintenance analysis instruction is sent. At the same time, based on the obtained transformer operation and maintenance analysis index, the transformer nodes with state changes in the transmission line knowledge graph are partially reconstructed; If the obtained transformer operation and maintenance analysis index is greater than the transformer operation and maintenance analysis index preset in the database, the pollution level threshold of the corresponding insulator of the transformer is updated based on the obtained transformer operation and maintenance analysis index deviation.

8. The method for DC transmission operation and maintenance analysis based on knowledge graph analysis according to claim 1, characterized in that: The specific process of judging whether the transmission line operation and maintenance analysis is completed based on the results of the transmission line operation and maintenance analysis is as follows: When the obtained transmission line operation and maintenance analysis index is not greater than the transmission line operation and maintenance analysis index preset in the database, the transmission line operation and maintenance analysis is completed and a fault location instruction is sent. At the same time, the operation and maintenance strategy is formulated and optimized based on the result of the fault location. Otherwise, the DC power setting value of the transformer is adjusted based on the deviation of the obtained transmission line operation and maintenance analysis index; The DC power setting value is used to adjust the operating state of the DC transmission line where the transformer is located.

9. The method for DC transmission operation and maintenance analysis based on knowledge graph analysis according to claim 8, characterized in that: The transmission line operation and maintenance analysis indicators are obtained by the following method: The obtained controller operation and maintenance analysis indicator is corrected by the controller operation and maintenance analysis indicator weight factor to obtain the controller operation and maintenance analysis indicator influence score. At the same time, the obtained transformer operation and maintenance analysis indicator is corrected by the transformer operation and maintenance analysis indicator weight factor to obtain the transformer operation and maintenance analysis indicator influence score. Input the acquired first and second operation and maintenance data into the transmission line knowledge graph, and simultaneously acquire the third operation and maintenance data of the DC transmission line at the current operation and maintenance analysis moment. Perform ratio weighting processing on the acquired third operation and maintenance data and the corresponding third operation and maintenance data set value in the database to obtain the conductor vibration amplitude influence score, the conductor transmission temperature influence score, and the second geomagnetic induction current influence score; The obtained conductor vibration amplitude influence score, conductor transmission temperature influence score and second geomagnetic induction current influence score are coupled to obtain the transmission line operation and maintenance analysis index influence score. At the same time, the obtained controller operation and maintenance analysis index influence score, transformer operation and maintenance analysis index influence score and transmission line operation and maintenance analysis index influence score are coupled to obtain the transmission line operation and maintenance analysis index. The third operation and maintenance data includes the conductor vibration amplitude, the conductor transmission temperature, and the second geomagnetic induction current; The conductor vibration amplitude influence score represents the result of the conductor vibration amplitude weight factor correcting the difference between the obtained conductor vibration amplitude and the conductor vibration amplitude set value in the database; The conductor transmission temperature influence score represents the result of the conductor transmission temperature weight factor correcting the difference between the acquired conductor transmission temperature and the conductor transmission temperature setting value in the database; The second geomagnetic induction current influence score represents a result of correcting the difference between the acquired second geomagnetic induction current and the second geomagnetic induction current set value in the database by the second geomagnetic induction current weight factor; The transmission line operation and maintenance analysis index impact score represents quantitative data of the impact degree of the third operation and maintenance data on the stability of the DC transmission line; The transmission line operation and maintenance analysis index represents quantitative data of the degree of influence of the controller operation and maintenance analysis index, the transformer operation and maintenance analysis index and the third operation and maintenance data on the stability of the direct current transmission line.

10. A DC transmission operation and maintenance analysis system based on knowledge graph analysis, characterized in that: include: Controller operation and maintenance analysis module, transformer operation and maintenance analysis module, and transmission line operation and maintenance analysis module; The controller operation and maintenance analysis module is used to perform controller operation and maintenance analysis based on the first operation and maintenance data in the transmission line knowledge graph to determine whether to perform transformer operation and maintenance analysis; The transformer operation and maintenance analysis module is used to determine whether to perform transmission line operation and maintenance analysis based on the results of the transformer operation and maintenance analysis if the transformer operation and maintenance analysis is performed; The transmission line operation and maintenance analysis module is used to determine whether the transmission line operation and maintenance analysis is completed based on the results of the transmission line operation and maintenance analysis if the transmission line operation and maintenance analysis is performed.

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