Method for determining occurrence frequency of system maintenance types of hybrid converter station

Abstract

The invention provides a hybrid converter station system maintenance type occurrence frequency determination method. The method comprises the steps that S101, the initial operation life of each element in a system is acquired; s102, determining an initial life matrix based on the initial operation life of each element; s103, determining a residual life matrix based on the initial life matrix; s104, based on the residual life matrix, determining the comprehensive residual life of the converter system; s105, determining the maintenance type of the system in the current operation period based on the comprehensive residual life of the converter system; and S106, based on the maintenance type of the system in the current operation period, determining the occurrence frequency of each maintenance type in the simulation iteration period of the system. The prediction precision of the maintenance frequency model is improved through multiple simulation iterations, and a more accurate quantitative theoretical basis is provided for formulating an optimal maintenance strategy on the premise of ensuring reliable operation of the system.

Description

Technical Field

[0001] The present application relates to the field of power systems, and in particular to a method for determining the number of occurrences of maintenance types in a hybrid converter station system. Background Art

[0002] The installed capacity of renewable energy sources, represented by wind power and photovoltaics, continues to grow rapidly. This has led to increasing technical challenges such as insufficient grid strength and transient overvoltages, placing higher demands on high-voltage, large-capacity, and long-distance DC transmission technologies. Currently, the mainstream DC transmission technologies are based on two topologies: line-commutated converters (LCCs) and modular multilevel converters (MMCs). While LCCs offer high capacity and low losses, they are susceptible to commutation failures. While MMCs offer flexible power regulation and low harmonic content, they are limited by the performance of IGBT devices, which restricts transmission capacity. Therefore, the construction of LCC-MMC hybrid DC transmission systems, which considers the advantages of both commutation topologies, has become a research hotspot. This approach addresses the challenge of a single topology being unable to meet the power transmission needs of diverse renewable energy sources and promotes the diversification of DC transmission topologies.

[0003] While hybrid converter stations meet the various demands of new energy transmission, they also bring about complex power system design and operation requirements. To ensure the long-term operation of the converter station, not only does it pose a challenge to the electrical performance of the converter station itself, but it also places higher demands on the optimization of subsequent operation and maintenance strategies. As a key indicator in the optimization of operation and maintenance strategies, the precise quantitative analysis of the number of maintenance times can provide a scientific decision-making basis for actual projects to optimize strategy costs while ensuring equipment reliability. However, traditional calculations of the number of maintenance times are often based on ideal operating conditions. For example, they ignore the coupling relationship between converter station equipment and the different failure modes that exist in different life cycle stages of the same equipment. This may lead to discrepancies with the actual project maintenance situation, thereby affecting the reliability and cost-effectiveness of the converter station operation. Summary of the Invention

[0004] In order to overcome the above technical deficiencies, the present application provides a method for determining the number of occurrences of maintenance types in a hybrid converter station system. To achieve the above objectives, the present application is implemented according to the following technical solutions: The present application provides a method for determining the number of occurrences of maintenance types in a hybrid converter station system, comprising: Step S101: obtaining the initial operating life of each component in the system; Step S102: determining an initial life matrix based on the initial operating life of each component; Step S103: determining a remaining life matrix based on the initial life matrix, wherein the remaining life matrix is ​​a matrix of components that have been repaired and inspected but have not had their faults replaced during the current operation cycle; Step S104: determining the comprehensive remaining lifetime of the commutation system based on the remaining lifetime matrix; Step S105: determining the maintenance type within the current operation cycle of the system based on the comprehensive remaining life of the commutation system; Step S106: Based on the maintenance types in the current operation cycle of the system, the occurrence frequency of each maintenance type in the system simulation iteration cycle is determined.

[0005] Optionally, the initial operating life of each component in the system is determined as follows: A probability sampling method is used to determine the initial operating life of each component of the system.

[0006] Optionally, determining an initial life matrix based on the initial operating life of each component includes: The initial operating life of each component is classified according to the preset component type and stored in blocks to form an initial life matrix.

[0007] Optionally, determining a remaining life matrix based on the initial life matrix includes: Obtaining the working duration of the current operation cycle and a unit matrix of the same dimension, wherein the working duration of the current operation cycle is the working duration determined in the previous operation cycle; A remaining life matrix is ​​determined based on the initial life matrix, the working duration of the current operation cycle and the identity matrix.

[0008] Optionally, determining the comprehensive remaining lifetime of the commutation system based on the remaining lifetime matrix includes: Dividing the remaining life matrix into blocks according to component categories, and sorting the initial operating lives of the components in each block in ascending order to obtain a sorted block life matrix; Obtaining the redundancy configuration of components within the system topology; Based on the redundant configuration of the components in the system topology and the block lifetime matrix, a comprehensive remaining lifetime of the commutation system is determined.

[0009] Optionally, determining the maintenance type within the current operation cycle of the system based on the comprehensive remaining life of the commutation system includes: Determining whether the comprehensive remaining life of the commutation system is less than a preset maintenance period; If so, it is determined that the maintenance type in the current operation cycle of the system is fault maintenance; If not, it is determined that the maintenance type in the current operation cycle of the system is preventive maintenance.

[0010] Optionally, determining the number of occurrences of each maintenance type within a simulation iteration cycle based on the maintenance type within the current operation cycle of the system includes: Perform breakdown repairs; Determining the working duration of the next operation cycle based on the comprehensive remaining life of the commutation system and the preset maintenance cycle; For the elements in the block life matrix whose working time is less than the working time of the current operation cycle, sampling and replacing are performed, and the block life matrix after sampling and replacing is used as the initial life matrix of the next operation cycle; Determine whether the total running time of the current system reaches a first preset duration; If so, determine the number of occurrences of each maintenance type within the total operating time of the current system; Determine whether the current number of simulation iterations reaches a first preset number of iterations; If so, determine the number of occurrences of each maintenance type within the simulation iteration cycle; If not, execute steps S101-S106 to perform the next simulation iteration calculation.

[0011] Optionally, when the result of determining whether the total running time of the current system reaches the first preset duration is no, the subsequent steps are: Execute steps S103-S105.

[0012] Optionally, the determining the number of occurrences of each maintenance type within a simulation iteration cycle based on the maintenance type within the current operation cycle of the system further includes: Perform preventive maintenance; Determining the working duration of the next operation cycle based on the comprehensive remaining life of the commutation system and the preset maintenance cycle; For the elements in the block life matrix whose working time is less than the working time of the current operation cycle, sampling and replacing are performed, and the block life matrix after sampling and replacing is used as the initial life matrix of the next operation cycle; Determine whether the total running time of the current system reaches a first preset duration; If so, determine the number of occurrences of each maintenance type within the total operating time of the current system; Determine whether the current number of simulation iterations reaches a first preset number of iterations; If so, determine the number of occurrences of each maintenance type within the simulation iteration cycle; If not, execute steps S101-S106 to perform the next simulation iteration calculation.

[0013] Optionally, when the result of determining whether the total running time of the current system has reached the first preset duration is no, the subsequent steps are: Execute steps S103-S105.

[0014] This application has the following beneficial effects: The method proposed in this application targets the impact of dynamic factors such as equipment aging and the mutual influence mechanism between modules on the operation and maintenance process, introduces the converter station reliability index to predict the required failure rate in the sampling process, and ensures the credibility of the life prediction results. It also updates the initial life of the operating cycle by locating and replacing faulty components to reflect the "local life update" characteristics in actual engineering, and realizes accurate analytical calculation of the number of various maintenance occurrences in the hybrid converter station. At the same time, through multiple simulation iterations, the prediction accuracy of the maintenance number model is improved, providing a more accurate quantitative theoretical basis for formulating the optimal maintenance strategy under the premise of ensuring reliable system operation.

[0015] In addition to the above-described purposes, features and advantages, the present application also has other purposes, features and advantages. The present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings: Figure 1 This is a flow chart of a method for determining the number of occurrences of maintenance types of a hybrid converter station system provided by an embodiment of the present application; Figure 2 This is a schematic diagram of the main circuit of a modular multilevel converter provided in an embodiment of the present application; Figure 3 This is a schematic diagram of the main circuit of the grid phase-commutation commutation system provided in an embodiment of the present application; Figure 4 This is a schematic diagram of the relationship between the maintenance trigger mechanism and the preset cycle provided in the embodiment of the present application. Figure 4 (a) is a schematic diagram of the batch replacement strategy, Figure 4 (b) is a schematic diagram of the age replacement strategy. DETAILED DESCRIPTION

[0017] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in many different ways as defined and covered by the claims.

[0018] Therefore, in order to solve the above problems, Figure 1 As shown, the present application proposes a method for determining the number of occurrences of maintenance types of a hybrid converter station system, comprising: Step S101: obtaining the initial operating life of each component in the system; The hybrid converter station system of this application mainly includes a modular multi-level converter and a grid-commutated converter system, such as Figure 2 As shown in Figure 1, the main circuit of the modular multilevel converter consists of six bridge arms, with the upper and lower bridge arms forming a phase unit. Each bridge arm consists of a bridge arm reactor and k submodules connected in series. Here, the same number of half-bridge and full-bridge submodules are used. To improve the reliability of the MMC, each bridge arm is equipped with nk submodules as redundant modules (where n is the total number of bridge arm submodules). Figure 3 As shown in FIG, the main circuit of the grid-commutated commutation system consists of two groups of 6-pulse commutation bridges, which achieve a 30° phase difference through star- and delta-connected transformers. Each bridge group contains 6 thyristor valve arms, and each valve arm consists of multiple series-connected thyristors.

[0019] It can be seen that the converter station contains multiple components. This application is based on the relationship between the system operating life and reliability, that is, Figure 2 and Figure 3 The calculation expression of the system operating life and reliability shown in the converter station can also be understood as the calculation expression of the life before the converter station maintenance, that is: (1) in, t For the system operating life, R For reliability, λ is the system failure rate.

[0020] To quantify the mutual influence between modules in the sampling process system, the failure rate should be predicted based on the reliability index of the hybrid system. Therefore, probability sampling (uniformly distributed random number sampling) is used to determine the initial operating life of each component: (2) in, is the initial operating life of the component, is a random number that obeys the standard uniform distribution, EENS is the expected value of energy shortage, T is the downtime when the equipment fails. P For power shortage.

[0021] Step S102: determining an initial life matrix based on the initial operating life of each component; The initial operating life of each component calculated in step S101 can be understood as the random life of all components in the converter station. Then, the initial operating life of each component is classified according to the preset component type and stored in blocks to form an initial life matrix. A m-1 ,The preset component types generally include sub-modules, thyristors, and reactors.

[0022] Step S103: determining a remaining life matrix based on the initial life matrix, wherein the remaining life matrix is ​​a matrix of components that have been repaired and inspected but have not had their faulty components replaced; Due to the characteristics of "partial life update" of the system in engineering practice, maintenance operations can only restore partial performance of the component rather than completely reset the life. Then obtain the working time of the current operation cycle T U_m-1 , combined with the unit matrix of the same dimension as the correction matrix to determine the remaining life matrix , the remaining life matrix is ​​the matrix of the faulty components that have been repaired and inspected but not replaced during the current operating cycle: (3) in, J is the identity matrix of the same dimension as the lifetime matrix, and n is the dimension of the identity matrix.

[0023] It should be noted that the working time of the current operation cycle is the working time determined in the previous operation cycle. The specific calculation method will be explained in detail later and will not be mentioned here.

[0024] Step S104: determining the comprehensive remaining lifetime of the commutation system based on the remaining lifetime matrix; First, the remaining life matrix is ​​divided into blocks according to the component category, and then the initial operating life of the components in each block is sorted in ascending order to obtain the sorted block life matrix, and then the analysis is carried out. Figure 1 、 Figure 2 The redundant configuration of components (submodules, thyristors) within the system topology is used to determine the system operating status based on the minimum redundancy constraints for stable operation. The specific determination method will be described in detail later and will not be elaborated here.

[0025] Due to different redundancy designs for converter stations, the minimum redundancy constraints vary in system operating states. MMC relies on submodule redundancy to support online replacement of faulty modules, while LCC relies on system-level redundancy. Maintenance typically requires partial or complete shutdown, and unlike MMC, it cannot simply bypass the faulty submodule to maintain operation. Therefore, the overall remaining life of the converter system can be determined based on the redundant configuration of components within the system topology and the block life matrix: (4) Where, is the comprehensive remaining life of the MMC commutation system, is the comprehensive remaining life of the LCC commutation system, is the block lifespan matrix after sorting; i 、 j They represent the number of bridge arms and components of the system respectively, and s and p represent the series and parallel relationships of the system.

[0026] Step S105: determining the maintenance type within the current operation cycle of the system based on the comprehensive remaining life of the commutation system; Set the system maintenance cycle, then analyze and determine the relationship between the comprehensive remaining life of the commutation system and the preset maintenance cycle, and record the number of maintenance times after the fault N f and preventive maintenance times N p .

[0027] Figure 4 This is a diagram showing the relationship between the two maintenance trigger mechanisms, preventive maintenance and fault maintenance, and the preset cycle. Among them, preventive maintenance strictly follows the preset cycle for maintenance. T It is a fixed cycle; while fault maintenance depends on the real-time operation status assessment results and is triggered when the equipment is confirmed to be faulty.

[0028] Determine whether the remaining service life of the commutation system is less than the preset maintenance period. τ s_m Less than the preset maintenance period T p When the judgment result is , it can be determined that the maintenance type in the current operation cycle of the system is fault maintenance. When the judgment result is no, it is determined that the maintenance type in the current operation cycle of the system is preventive maintenance, as shown in the following formula: (5) Where: N f For fault repairs, N p For preventive maintenance.

[0029] Step S106: determining the number of occurrences of each maintenance type within a system simulation iteration cycle based on the maintenance type within the current operation cycle of the system; After determining the maintenance type, the corresponding maintenance can be carried out according to the corresponding maintenance type. That is, if the maintenance type is a fault type, fault repair can be carried out. Then, the working time of the next operation cycle can be determined based on the comprehensive remaining life of the commutation system and the preset maintenance cycle, as shown in the following formula: (6) During maintenance, due to the system's "local life update" feature, the system will only update the repaired and replaced parts. To ensure that the system can complete its work smoothly within the current operating cycle, the components in the block life matrix that are less than the current operating cycle working time are sampled and replaced. The initial operating life of the replaced components can be determined, that is: (7) Where: is the initial operating life of the replaced component, is the repair rate, is a random number that follows a standard uniform distribution.

[0030] After replacing a component, the initial operating lifespan corresponding to the replaced component is determined. The sampled block lifespan matrix after replacement is then used as the initial lifespan matrix for the next operating cycle. Since a system's total operating time includes multiple operating cycles, the next step is to determine whether the current system's total operating time has reached a first preset duration. If so, the number of occurrences of each maintenance type within the current system's total operating time is determined, namely, the number of occurrences of fault repairs and preventive maintenance. If the result of this determination does not reach the first preset duration, steps S103 through S105 are executed to calculate and iterate for the next operating cycle.

[0031] In order to improve the prediction accuracy of the maintenance frequency model, multiple simulations are required. Therefore, after determining the number of occurrences of fault maintenance and preventive maintenance, it is necessary to determine whether the current number of simulation iterations has reached the first preset number. If so, the number of occurrences of each maintenance type within the simulation iteration cycle is determined. If it has not reached the first preset number, steps S101-S106 are repeated to perform the next simulation iteration calculation.

[0032] After determining that the fault type is preventive maintenance, you can perform preventive maintenance. Since the processing after maintenance and after performing fault maintenance is similar, only a brief description of the subsequent processing flow is given here, and the specific processing is not detailed again: After performing preventive maintenance, the operating time of the next operating cycle is determined based on the comprehensive remaining life of the converter station system. The elements in the block life matrix that are less than the operating time of the current operating cycle are then sampled and replaced. The block life matrix after sampling and replacement is used as the initial life matrix for the next operating cycle. It is then determined whether the total operating time of the current system has reached a first preset time. If so, the number of occurrences of each maintenance type within the total operating time of the current system is determined. If not, steps S103-S105 are executed to calculate and iterate the next operating cycle. When the first preset time is reached, it is determined whether the current number of simulation iterations has reached the first preset number of iterations. If so, the number of occurrences of each maintenance type within the simulation iteration cycle is determined. If not, steps S101-106 are executed to perform the next simulation iteration calculation.

[0033] It should be noted that the first preset duration and the first preset number of iterations can be set according to actual needs and will not be described in detail here.

[0034] After reaching the first preset number of iterations, the number of occurrences of each maintenance type within the system simulation iteration cycle is counted, and then the number of occurrences of each maintenance type can be divided by the first preset number of iterations to determine the average number of occurrences of each maintenance type.

[0035] In summary, the method proposed in this application targets the impact of dynamic factors such as equipment aging and the mutual influence mechanism between modules on the operation and maintenance process, introduces the converter station reliability index to predict the required failure rate in the sampling process, and ensures the credibility of the life prediction results. It also updates the initial life of the operating cycle by locating and replacing faulty components to reflect the "local life update" characteristics in actual engineering, and realizes accurate analytical calculation of the number of various maintenance occurrences in the hybrid converter station. At the same time, through multiple simulation iterations, the prediction accuracy of the maintenance number model is improved, providing a more accurate quantitative theoretical basis for formulating the optimal maintenance strategy while ensuring the reliable operation of the system.

[0036] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for determining the number of occurrences of maintenance types in a hybrid converter station system, characterized in that: include: Step S101: obtaining the initial operating life of each component in the system; Step S102: determining an initial life matrix based on the initial operating life of each component; Step S103: determining a remaining life matrix based on the initial life matrix, wherein the remaining life matrix is ​​a matrix of components that have been repaired and inspected but have not had their faults replaced during the current operation cycle; Step S104: determining the comprehensive remaining lifetime of the commutation system based on the remaining lifetime matrix; Step S105: determining the maintenance type within the current operation cycle of the system based on the comprehensive remaining life of the commutation system; Step S106: Based on the maintenance types in the current operation cycle of the system, the occurrence frequency of each maintenance type in the system simulation iteration cycle is determined.

2. The method according to claim 1, characterized in that The initial operating life of each component in the system is determined as follows: A probability sampling method is used to determine the initial operating life of each component of the system.

3. The method according to claim 1, characterized in that Determining an initial life matrix based on the initial operating life of each component includes: The initial operating life of each component is classified according to the preset component type and stored in blocks to form an initial life matrix.

4. The method according to claim 3, characterized in that The determining of the remaining life matrix based on the initial life matrix includes: Obtaining the working duration of the current operation cycle and a unit matrix of the same dimension, wherein the working duration of the current operation cycle is the working duration determined in the previous operation cycle; A remaining life matrix is ​​determined based on the initial life matrix, the working duration of the current operation cycle and the identity matrix.

5. The method according to claim 4, characterized in that The determining of the comprehensive remaining lifetime of the commutation system based on the remaining lifetime matrix includes: Dividing the remaining life matrix into blocks according to component categories, and sorting the initial operating lives of the components in each block in ascending order to obtain a sorted block life matrix; Obtaining the redundancy configuration of components within the system topology; Based on the redundant configuration of the components in the system topology and the block lifetime matrix, a comprehensive remaining lifetime of the commutation system is determined.

6. The method according to claim 1 or 5, characterized in that The determining of the maintenance type within the current operation cycle of the system based on the comprehensive remaining life of the commutation system includes: Determining whether the comprehensive remaining life of the commutation system is less than a preset maintenance period; If so, it is determined that the maintenance type in the current operation cycle of the system is fault maintenance; If not, it is determined that the maintenance type in the current operation cycle of the system is preventive maintenance.

7. The method according to claim 6, characterized in that The determining, based on the maintenance type in the current operation cycle of the system, the number of occurrences of each maintenance type in the simulation iteration cycle includes: Perform breakdown repairs; Determining the working duration of the next operation cycle based on the comprehensive remaining life of the commutation system and the preset maintenance cycle; For the elements in the block life matrix whose working time is less than the working time of the current operation cycle, sampling and replacing are performed, and the block life matrix after sampling and replacing is used as the initial life matrix of the next operation cycle; Determine whether the total running time of the current system reaches a first preset duration; If so, determine the number of occurrences of each maintenance type within the total operating time of the current system; Determine whether the current number of simulation iterations reaches a first preset number of iterations; If so, determine the number of occurrences of each maintenance type within the simulation iteration cycle; If not, execute steps S101-S106 to perform the next simulation iteration calculation.

8. The method according to claim 7, characterized in that When the result of determining whether the total running time of the current system has reached the first preset duration is no, the subsequent steps are: Execute steps S103-S105.

9. The method according to claim 6, characterized in that The determining, based on the maintenance types in the current operation cycle of the system, the number of occurrences of each maintenance type in a simulation iteration cycle further includes: Perform preventive maintenance; Determining the working duration of the next operation cycle based on the comprehensive remaining life of the commutation system and the preset maintenance cycle; For the elements in the block life matrix whose working time is less than the working time of the current operation cycle, sampling and replacing are performed, and the block life matrix after sampling and replacing is used as the initial life matrix of the next operation cycle; Determine whether the total running time of the current system reaches a first preset duration; If so, determine the number of occurrences of each maintenance type within the total operating time of the current system; Determine whether the current number of simulation iterations reaches a first preset number of iterations; If so, determine the number of occurrences of each maintenance type within the simulation iteration cycle; If not, execute steps S101-S106 to perform the next simulation iteration calculation.

10. The method according to claim 8, characterized in that When the result of determining whether the total running time of the current system has reached the first preset duration is no, the subsequent steps are: Execute steps S103-S105.

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