Active power distribution network secondary system planning method

Abstract

The invention discloses an active power distribution network secondary system planning method, and relates to the technical field of power system planning, and the planning method comprises the following steps: regional characteristic deep analysis, differential fault processing configuration scheme making, medium and low voltage terminal function extension and optimization path exploration, and differential power distribution terminal partition deployment strategy. And formulating a primary and secondary system overall planning technical principle, and scientifically formulating a power distribution network secondary system planning design technical principle oriented to the differentiated primary network frame. According to the invention, through careful analysis of the influence of new energy access, a targeted protection logic and a cooperative control strategy are designed, a fault area can be accurately identified and rapidly isolated under loads of different positions and types, the power failure time of users in a non-fault area is reduced, and through implementation of a differentiated partition deployment strategy, the power failure rate of the users in the non-fault area is improved. And each power supply area can obtain power distribution terminal configuration most suitable for self requirements, so that the fault processing capability is further enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of power system planning, and in particular to a secondary system planning method for an active distribution network. Background Art

[0002] With the transformation of energy structure and the advancement of sustainable development, the penetration rate of new energy in the power system continues to increase. As an important part of the power system, the active distribution network must not only accept the electricity of traditional energy, but also adapt to the access of new energy, such as wind energy, solar energy and other distributed energy. This high penetration rate of new energy access has brought new challenges to the operation and control of the distribution network, especially in the planning and management of the secondary system. The secondary system of the distribution network covers key technologies such as protection, control, automation, and communication, which are crucial to ensuring the safe, stable and economical operation of the power grid.

[0003] However, the existing distribution network secondary system planning method fails to fully consider the characteristics of different power supply areas, such as differences in key parameters such as short-circuit capacity, power supply radius, load rate, new energy access points and access capacity. This makes it difficult for fault handling configuration solutions to accurately adapt to the needs of each region and it is impossible to achieve refined management of fault handling strategies. In terms of differentiated deployment, the existing technology ignores the differentiated needs of different power supply areas for distribution terminals and fails to carry out reasonable zoning deployment in combination with regional development plans, resulting in unreasonable resource allocation, over-investment in some areas, and insufficient equipment in other areas with higher demand, affecting power supply reliability and service quality.

[0004] In summary, the existing distribution network secondary system planning methods have obvious defects in differentiation and differentiated deployment, and cannot meet the development needs of high-penetration active distribution networks. Therefore, there is an urgent need for an innovative secondary system planning method that can deeply analyze the characteristics of each power supply area and formulate targeted differentiated fault handling configuration plans and zoning deployment strategies. Summary of the invention

[0005] The purpose of the present invention is to make up for the shortcomings of the prior art and provide a secondary system planning method for an active distribution network. It can optimize the timing coordination relationship of distribution network protection, safety automatic devices, new energy control and distribution automation through a coordinated coordination scheme for fault handling, and more finely control the fault handling process through a coordinated coordination scheme of staged overcurrent protection and main transformer gap protection, reduce interference with power grid operation, and improve the adaptability of the power grid to the volatility of new energy.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a secondary system planning method for an active power distribution network, the planning method comprising the following steps:

[0007] S100, in-depth analysis of regional characteristics: in-depth analysis of key parameters such as short-circuit capacity, power supply radius, load rate, new energy access points and access capacity of each power supply area, forming a detailed regional characteristics database, evaluating the differentiated needs of each region for fault handling capabilities, and providing basic data support for subsequent differentiated configuration solutions;

[0008] S200, formulation of differentiated fault handling configuration schemes: Analyze the electrical parameters of different power supply areas, evaluate the impact of new energy access points and their capacity, and design customized fault handling configuration schemes for different power supply areas;

[0009] S300, Exploration of the function expansion and optimization path of medium and low voltage terminals: Based on differentiated configuration schemes, clarify the functional requirements of low and medium voltage terminals in each region, develop terminal function expansions that adapt to the characteristics of different regions, and formulate differentiated step-by-step deployment strategies based on the theory of full life cycle management to synchronize terminals with regional development needs;

[0010] S400, differentiated distribution terminal zoning deployment strategy: Combined with regional development planning, the differentiated configuration scheme is refined into specific zoning deployment strategies so that each region can obtain the most suitable distribution terminal configuration. Before implementation, economic benefit evaluation is carried out and the possibility of future expansion is considered;

[0011] S500, formulation of technical principles for coordinated planning of primary and secondary systems: comprehensive integration of professional technical solutions such as power grid control, fault handling, data collection, communication networking and safety protection, and scientific formulation of technical principles for planning and design of distribution network secondary systems for differentiated primary grids.

[0012] Furthermore, the specific steps of the S100 regional characteristics in-depth analysis for the impact assessment of new energy access and protection strategy design are as follows:

[0013] Analysis of new energy access characteristics: Analyze the impact of new energy wind power and photovoltaic access on the fault characteristics of the distribution network, focusing on the changes in fault current and the diversity of fault types;

[0014] Risk assessment and protection logic design: Assess the vulnerable points and risk areas of the distribution network after the integration of new energy, and design corresponding overcurrent protection and grounding protection logic;

[0015] Sequential logic and coordinated control: Design the sequential logic between protection and backup automatic switching and reclosing safety automatic devices, integrate the coordinated action strategy of new energy control devices and distribution automation systems, including anti-islanding protection strategy;

[0016] The collaborative strategy design includes:

[0017] Staged overcurrent protection: Design a multi-level protection strategy to ensure that the fault area can be quickly and accurately identified and isolated under different locations and types of loads and faults;

[0018] Main transformer gap protection: Design special protection logic for internal faults of the main transformer to prevent the fault from expanding and causing damage;

[0019] Reclosing optimization solution: When the instantaneous fault is eliminated, the circuit breaker is automatically reclosed to restore power supply;

[0020] Automatic backup, that is, the backup power supply is automatically put into use: when the main power supply fails, it automatically switches to the backup power supply to ensure the continuous power supply of important loads;

[0021] New energy anti-islanding protection: prevents the distributed energy system from continuing to supply power to the grid when a grid failure occurs, causing electric shock hazards to maintenance personnel and difficulties in grid restoration;

[0022] Feeder automation device: Utilizes intelligent terminals and communication networks to automatically detect, locate and isolate faults, and quickly restore power supply to non-faulty areas.

[0023] Furthermore, the S100 also includes a quantitative calculation of the fault handling capability of each region: defining a differentiated resilience index R D To evaluate the fault handling capability of each region, the formula is as follows:

[0024]

[0025] Where: k = 1, 2, .., N, N is the number of sampled scenes; i = 1, 2, .., T, T is the simulation duration; ΔT is the simulation step length; L i,k is the system load holding amount in the i-th simulation step under the k-th sampling scenario; L z is the total system load; L s,min,k is the minimum reserve of important loads in the kth sampling scenario; L s,z is the total amount of important load of the system; R re,k is the recovery speed index under the kth scenario; α is the weight of the recovery speed; using a coefficient of 0.5 can keep the resilience assessment result within a range;

[0026] R re,k Calculated by the following formula:

[0027]

[0028] Where f(t) is the recovery rate function at time t. Assuming that the power grid has different recovery rates at different recovery stages, f(t) is estimated using a piecewise linear model. The formula is as follows:

[0029]

[0030] where c1, c2…c n are different recovery rates at different recovery stages, c1, c2…c n It can be obtained by measurement;

[0031] The weight α can be adjusted according to the risk preferences and strategies of the grid operator.

[0032] Furthermore, the S200 differentiated fault handling configuration scheme is formulated based on the differences in the main distribution network, and an overall configuration scheme and a differentiated design scheme for active distribution network fault handling are proposed to meet the specific needs of different power supply areas. The specific steps are as follows:

[0033] S201, power supply area characteristics analysis: collect and analyze in detail the electrical parameters of different power supply areas and new energy access points and their capacities, and determine the key performance indicators of each power supply area;

[0034] S202, fault handling configuration analysis: based on the collected data, analyzing the fault characteristics of different power supply areas, including fault type, frequency and duration;

[0035] S203, formulation of differentiated configuration schemes: design specific fault handling configuration schemes according to the characteristics of the power supply area, including adjusting protection settings, optimizing equipment layout and adding intelligent control units, evaluating the economic and feasibility of different configuration schemes, and formulating emergency response plans, including fault early warning, rapid isolation and automatic recovery strategies;

[0036] S204, solution implementation and verification: Implement differentiated fault handling configuration solutions in the power supply area, and conduct simulation tests and field trials.

[0037] Furthermore, the specific steps of S300 are:

[0038] S301, Current Status Analysis and Functional Evaluation: Detailed analysis of the functions of existing medium and low voltage terminals and edge IoT agents, including basic functions of data collection, status monitoring, remote control and fault diagnosis, and evaluation of terminal performance indicators, including data transmission rate, power consumption, storage capacity, and computing power;

[0039] S302, Demand forecasting and scenario construction: Based on the grid development plan and future demand forecast, different usage scenarios are constructed, including: high-density residential areas, industrial areas, commercial areas, rural areas, and load management, distributed energy access, and electric vehicle charging facility support;

[0040] S303, cluster analysis and functional requirement matching: use clustering technology to classify medium and low voltage terminals, and classify the terminals into different categories according to their functional characteristics and application scenarios;

[0041] S304, function expansion path planning: based on the results of cluster analysis, plan the optimal path for function expansion, which involves hardware upgrades, software updates, and development of new function modules;

[0042] S305, Economic Benefit Analysis: Estimate the cost of each functional expansion plan, including direct and indirect costs, and evaluate the economic benefits that the expanded terminal can bring, including reducing operation and maintenance costs, improving service quality, and increasing user satisfaction.

[0043] Furthermore, the active power distribution secondary system is used to implement all technologies and equipment for power grid monitoring, control, protection and automation functions, including components:

[0044] Distribution network protection device: used to detect grid faults and quickly act to isolate the faulty area;

[0045] Safety automatic device: Automation equipment used to automatically implement safety measures, i.e. automatic reclosing of circuit breakers;

[0046] New energy control system: manage and control new energy resources connected to the power grid to ensure their stable integration into the grid;

[0047] Distribution Automation System (DAS): An integrated automation system that monitors and controls the operation of the distribution network, improving response speed and efficiency;

[0048] Communication systems: including communication technology, data transmission and information exchange between systems;

[0049] Data acquisition system: collects power grid operation data to provide support for analysis and decision-making;

[0050] Security protection system: Cybersecurity and physical security of the power grid to prevent malicious attacks and unauthorized access.

[0051] Furthermore, according to the requirements of fault handling and dispatching control, medium and low voltage lines should be equipped with circuit breakers, power grid terminals and other equipment at locations such as cable line trunk line inlet and outlet, overhead line trunk line segmentation and branching, user boundary, reactive power compensation, etc. Overhead lines should promote the application of primary and secondary fusion pole switches. The S303 clustering analysis and functional requirement matching use clustering technology to explore the functional expansion and optimization path of medium and low voltage terminals. The medium and low voltage terminals include trunk line terminals, protection configuration terminals, branch terminals and user terminals. For the medium and low voltage terminal T, that is, T={t1,t2,…,t n}, where each terminal t i Represented as a feature vector Xi =x i1 ,x i2 ,…,x im ], m is the number of features, for the set of application scenarios S = {s1, s2, ..., s k}, each scene s j There is a corresponding weight W j , define terminal t i and scenes j The distance between D ij It is the terminal i and scenes j The distance between jl It's scenes j The weight of feature l, μ jl It's scenes j The average value of feature l in , based on the distance metric, the objective function of the clustering problem is defined as Find C={C1,C2,…,C k}, so that j is the smallest, where C j Belongs to scenes j After clustering, the functional expansion direction and priority of each category are determined based on the common functional characteristics of the terminals in each category.

[0052] Furthermore, the specific steps of S400 are:

[0053] S401, demand collection and analysis: collect detailed information on different power supply areas, including geographical distribution, load characteristics, network structure, and new energy access, and analyze the specific needs of these areas for distribution terminals, including data collection frequency, communication bandwidth, and real-time control capabilities;

[0054] S402, regional classification: classify the power supply areas according to their similarities, and the classification basis includes but is not limited to power supply radius, load type, user density, and new energy penetration rate;

[0055] S403, Strategy formulation: Design a specific distribution terminal deployment strategy for each type of power supply area. The strategy takes into account the type, quantity, location of the terminal and the design of the communication network. For commercial areas with high load density, higher performance terminals and stronger communication capabilities are used. For remote agricultural areas, more attention is paid to the reliability and low maintenance requirements of the terminal.

[0056] S404, Economic Benefit Assessment: Conduct a cost-benefit analysis for each deployment strategy, including terminal procurement cost, installation cost, operation and maintenance cost, and potential savings, i.e., total cost including reduced fault recovery time and reduced energy waste. The long-term economic benefits of each strategy are obtained through the life cycle cost assessment model LCC.

[0057] S405, strategy optimization and adjustment: Based on the results of the economic benefit evaluation, the initially formulated strategy is optimized and adjusted, and repeated iterations are performed to find the deployment solution with the highest cost-effectiveness ratio;

[0058] S406, implementation and monitoring: execute the finalized differentiated partition deployment strategy. During the implementation process, establish a monitoring mechanism, regularly collect terminal operation data, and evaluate the actual effect of the strategy so as to make timely adjustments and optimizations.

[0059] Furthermore, the S401 economic benefit evaluation is used to analyze and optimize the functional expansion and deployment strategies of medium and low voltage terminals, identify the solution that minimizes the total cost, and consider the economic benefits and return on investment, including the total cost C, the total income B, and the economic benefit E. C includes terminal purchase cost C p 、Installation cost C i , Operation and maintenance cost C o , B includes the potential savings brought by terminal deployment, that is, reducing the failure recovery time B f , reduce energy waste B e , the specific cost and benefit are: C = C p +C i +C o , B=B f +B e , introduce the profit increase ratio indicator I brought by unit cost, R j is the potential revenue of the jth region, S j is the power supply importance weight of the jth region, which can be determined based on factors such as load density and user satisfaction. j is the deployment cost of the jth region. Combined with the profit increase ratio index I, its economic benefit evaluation is E innovative =I×E, through calculation, the cost of each functional expansion plan is accurately estimated, including direct costs such as hardware procurement and software development, as well as indirect costs such as training and maintenance, and the economic benefits that the expanded terminal can bring are comprehensively evaluated to determine the most ideal expansion strategy.

[0060] Furthermore, the system also studies the transient characteristics of fault traveling waves when different types of faults occur, the generation, propagation and attenuation characteristics of traveling waves in the distribution network, collects traveling wave signal data under different fault conditions, including parameters of waveform, frequency and amplitude, analyzes and processes traveling wave signals to extract key information required for fault detection, designs distribution terminal devices for real-time collection and processing of traveling wave signals, integrates fault detection into the distribution terminal devices, and tests them in actual distribution network environments, evaluates the fault detection speed, accuracy and reliability of the devices, optimizes them based on the test results, and formulates deployment strategies for distribution terminal devices, including the number, location and maintenance plans of the devices.

[0061] Compared with the prior art, this active distribution network secondary system planning method has the following beneficial effects:

[0062] 1. Through a detailed analysis of the impact of new energy access, the present invention designs targeted protection logic and collaborative control strategies, which can accurately identify and quickly isolate fault areas under different locations and types of loads, avoid fault spread, and reduce power outage time for users in non-fault areas;

[0063] Second, the present invention clarifies the functional requirements of the terminal according to the functional expansion and optimization path of the distribution terminal, develops terminal functional expansion solutions that adapt to the characteristics of different regions, synchronizes the terminal with the regional development needs, improves the flexibility and adaptability of the terminal, and through the implementation of differentiated zoning deployment strategies, each power supply area can obtain the distribution terminal configuration that best suits its own needs, further enhancing the fault handling capability;

[0064] 3. The present invention defines differentiated resilience indicators to quantify and calculate the fault handling capacity of each region, making the evaluation results more objective and accurate, and being able to analyze the specific conditions of each region in more detail. In the calculation, multiple factors including system load holdings, minimum holdings of important loads, and recovery speed are comprehensively considered, and the weight of recovery speed is introduced to increase the flexibility and accuracy of the evaluation. The evaluation results can guide the optimal allocation of resources in different regions, improve the resilience and reliability of the overall system, better prepare for and respond to possible emergencies, and reduce the impact of failures on the system.

[0065] Fourth, the present invention accurately evaluates the demand for fault handling capabilities in each power supply area through detailed in-depth analysis of regional characteristics, and accordingly formulates differentiated fault handling configuration schemes. This method avoids the one-size-fits-all configuration method in all areas, but flexibly adjusts the protection setting value and optimizes the equipment layout according to the characteristics of different areas, ensuring the effective use of resources;

[0066] 5. The present invention comprehensively considers multiple dimensions such as terminal procurement cost, installation cost, operation and maintenance cost, and potential savings, and accurately calculates the long-term economic benefits of each deployment strategy, which helps to select the solution with the highest cost-effectiveness ratio, improves resource utilization efficiency, reduces overall costs, and increases the economic benefits of power companies, while also providing users with more cost-effective services.

[0067] Other advantages, objectives and features of the present invention will be set forth in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0069] Figure 1 The operational flow chart of an active distribution network secondary system planning method is shown in FIG.

[0070] Figure 2 Develop a method step flow chart for the S200 differentiated fault handling configuration solution. DETAILED DESCRIPTION

[0071] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0072] Example 1

[0073] A secondary system planning method for an active distribution network, the method comprising the following steps: fault handling coordination plan, differentiated fault handling configuration plan formulation, medium and low voltage terminal function expansion and optimization path exploration, differentiated distribution terminal zoning deployment strategy, fault traveling wave transient characteristics, and primary and secondary system overall planning technical principles formulation.

[0074] First, enter the fault handling coordination plan stage (S100), analyze the impact of new energy access (such as wind power, photovoltaic) on the fault characteristics of the distribution network, including fault current changes and fault type diversity, evaluate the vulnerability and risk areas after high penetration of new energy access, and design the timing logic between the distribution network protection device and the safety automatic device to quickly isolate the fault and restore power supply, including:

[0075] Staged overcurrent protection: Design a multi-level protection strategy to ensure fast and accurate identification and isolation of the fault area;

[0076] Main transformer gap protection: Design protection logic for the internal faults of the main transformer to prevent the fault from expanding;

[0077] Reclosing optimization: Automatically recloses the circuit breaker to restore power to transient faults;

[0078] Backup automatic switch strategy: automatically switch to the backup power supply to ensure the power supply of important loads;

[0079] New energy anti-islanding protection: prevents distributed energy systems from continuing to supply power when the power grid fails, avoiding safety hazards;

[0080] Feeder automation device: Uses intelligent terminals and communication networks to automatically detect, locate and isolate faults, and quickly restore power supply to non-faulty areas.

[0081] Then, enter the differentiated fault handling configuration plan formulation stage (S200), comprehensively collect characteristic data such as short-circuit capacity, power supply radius, load rate, new energy access points and access capacity of different power supply areas, and carry out detailed and in-depth analysis. Based on the collected data, deeply analyze the fault characteristics of different power supply areas, covering aspects such as fault type, occurrence frequency and duration. At the same time, deeply explore the performance bottleneck and adaptability of existing fault handling equipment. According to the unique characteristics of the power supply area, innovatively design exclusive fault handling configuration plans, such as flexibly adjusting protection settings, scientifically optimizing equipment layout and reasonably increasing intelligent control units, etc., comprehensively evaluate the economic efficiency and feasibility of different configuration plans, and carefully formulate a complete emergency response plan, which includes accurate fault warning. , efficient and rapid isolation, and intelligent automatic recovery strategies, steadily implement differentiated fault handling configuration plans in the selected power supply areas, carry out rigorous simulation tests and field tests, comprehensively verify the effectiveness and safety of the plans, accurately adjust the plans according to the test results, and ensure that various complex fault conditions can be calmly dealt with in actual operation. Develop meticulous implementation details, covering equipment configuration, parameter setting, operating procedures, and maintenance guidelines, to effectively ensure that differentiated design plans can be efficiently implemented. For areas with higher load rates, the configuration of backup power supply equipment can be increased, and the protection settings can be optimized to increase the response speed. Simulation tests can simulate a variety of extreme fault conditions, such as multiple faults occurring at the same time or large fluctuations in new energy output, to verify the reliability of the plan.

[0082] Next, we enter the stage of exploring the path of expanding and optimizing the functions of medium and low voltage terminals (S300), and conduct a detailed analysis of the functions of existing medium and low voltage terminals and edge IoT agents, covering basic functions such as data collection, status monitoring, remote control and fault diagnosis, as well as value-added functions such as advanced analysis and predictive maintenance. We comprehensively evaluate the performance indicators of the terminals, such as data transmission rate, power consumption, storage capacity, and computing power. Based on the long-term development plan of the power grid and the accurate prediction of future needs, we carefully construct a variety of usage scenarios, such as high-density residential areas, industrial areas, commercial areas, and rural areas, and fully consider the specific needs of each scenario, such as Load management, distributed energy access, and support for electric vehicle charging facilities. Detailed classification of medium and low voltage terminals. Classification of terminals into different categories based on their functional characteristics and application scenarios. Clarification of the direction and priority of functional expansion for the specific needs of each category. Scientific planning of the optimal path for functional expansion based on the results of cluster analysis, involving hardware upgrades, software updates, and careful development of new functional modules. Accurate estimation of the cost of each functional expansion solution, including direct costs such as hardware procurement and software development, as well as indirect costs such as training and maintenance, etc., to comprehensively evaluate the economic benefits that the expanded terminals can bring.

[0083] Subsequently, the differentiated distribution terminal zoning deployment strategy stage (S400) is entered. Combined with the regional development plan, the differentiated configuration plan is further refined into a specific zoning deployment strategy. Before implementation, a comprehensive economic benefit evaluation is conducted on the strategy, and the possibility of future expansion is fully considered to ensure that each region can obtain the most suitable distribution terminal configuration.

[0084] Finally, enter the fault traveling wave transient characteristics stage (S500), comprehensively integrate professional technical solutions such as power grid control, fault handling, data acquisition, communication networking and safety protection, and scientifically formulate technical principles for the planning and design of the secondary system of the distribution network for differentiated primary grids to ensure efficient and stable operation of the entire system. Collect traveling wave signal data under different fault conditions, including waveform, frequency and amplitude parameters, extract key information, design distribution terminal devices for real-time collection and processing of traveling wave signals, test the devices in the actual distribution network environment, evaluate the fault detection speed, accuracy and reliability, and formulate technical principles for the planning and design of the secondary system of the distribution network for differentiated primary grids.

[0085] This embodiment covers all aspects of the secondary system planning of the active distribution network, from coordinated fault handling to terminal function expansion and deployment strategy formulation, ensuring the efficient and stable operation of the distribution network. Through careful analysis, testing and evaluation, this method can effectively respond to the challenges brought by the high penetration rate of new energy, improve the system response speed and processing efficiency, and maximize economic benefits.

[0086] Example 2

[0087] This embodiment aims to describe in detail a secondary system planning method for an active distribution network, realize the refined management of fault handling strategies through cluster analysis of the characteristics of different power supply areas, quickly and accurately identify and isolate power grid faults, and optimize resource allocation by using economic benefit evaluation to improve the economy and reliability of power grid operation.

[0088] In the specific implementation, first, we analyze the impact of new energy access on the fault characteristics of the distribution network, including aspects such as fault current changes and fault type diversity, comprehensively evaluate the vulnerable points and risk areas of the power grid after the access of new energy, and carefully design the timing logic between the distribution network protection device and the safety automatic device to ensure that the fault can be quickly isolated and power supply can be restored. At the same time, we conduct characteristic analysis of different power supply areas, covering key parameters such as short-circuit capacity and power supply radius, formulate differentiated fault handling configuration plans based on regional characteristics, and optimize protection settings and equipment layout.

[0089] Taking the typical grid structure of overhead lines of medium-voltage distribution network as an example, the substation outlet intervals CX1 and CX2 are usually equipped with complete protection functions and primary equipment, that is, integrated protection and measurement devices, and no upgrading and reconstruction work is required; the trunk line segment intervals include FD1, FD2, FD, FD3, and FD4, and primary and secondary fusion pole switches (including FTU, circuit breakers, voltage transformers, current transformers, etc.) should be installed according to the protection configuration requirements. If there is no protection configuration requirement, the status quo can be maintained; the branch intervals include branch 2, branch 3, branch 6, sub-branch 1, sub-branch 2, and sub-branch 3. Primary and secondary fusion pole switches should be installed according to the protection configuration requirements. If there is no protection configuration requirement, the status quo can be maintained; user boundary intervals, including PB1, PB4, PB5, PB2, PB3, and PB6, should all be equipped with primary and secondary fusion pole switches; parallel reactive compensation intervals should all be equipped with primary and secondary fusion pole switches; fault indicators should be installed at appropriate locations in combination with the requirements for accurate fault location;

[0090] Urban cable lines mainly use ring main units to realize cable inlet and outlet connections, that is, the outgoing cable line of the substation is connected to the branch switch of the ring main unit, and all user load cable lines are connected from the branch switch of the ring main unit. The outgoing cable line and the user load cable line are gathered to the busbar of the ring main unit, and the ring main units are connected through the outgoing cable line (communication line). Taking this grid structure as an example, the substation outlet intervals CX1 and CX2 are usually equipped with complete protection functions and primary equipment, and no upgrading or renovation is required; the main line incoming intervals include HW11, HW12, HW21, HW22, HW31, and HW32. Circuit breakers and DTUs (with protection functions) should be installed according to the protection configuration requirements. If there is no protection configuration requirement, the status quo can be maintained; the outgoing line intervals include hw11, hw12, hw13, hw21, hw22, hw23, hw31, hw32, and hw33. Circuit breakers and DTUs (with protection functions) should be installed according to the protection configuration requirements. If there is no protection configuration requirement, the status quo can be maintained; the user boundary intervals should be equipped with primary and secondary fusion pole switches.

[0091] Then, the functions of existing medium and low voltage terminals and IoT agents are deeply analyzed, their performance indicators are evaluated, and cluster analysis is performed based on the full life cycle theory. The relevant data of medium and low voltage terminals are collected, including computing power, deployment cost, communication requirements, maintainability and other characteristics. Feature vectors are selected and constructed to accurately represent the key attributes of the terminal. For medium and low voltage terminals T, that is, T = {t1, t2, …, t n}, where each terminal t i Represented as a feature vector X i =[x i1 ,x i2 ,…,x im], m is the number of features, for the set of application scenarios S = {s1, s2, ..., s k}, each scene s j There is a corresponding weight W j , define terminal t i and scenes j The distance between D ij It is the terminal i and scenes j The distance between jl It's scenes j The weight of feature l, μ jl It's scenes j The average value of feature l in , based on the distance metric, the objective function of the clustering problem is defined as Find C={C1,C2,…,C k}, so that j is the smallest, where C j Belongs to scenes j The terminal set is clustered, the clustering results are evaluated, and whether the expected clustering effect is met. According to the clustering results, the function expansion path of the terminal is adjusted, and hardware upgrades and software development are planned to achieve effective expansion of terminal functions.

[0092] Then, we comprehensively collect and analyze the differentiated needs of different power supply areas, formulate and evaluate the economic benefits of the regional deployment strategy, and consider the economic benefits and return on investment, including total cost C, total income B, and economic benefit E. C includes terminal purchase cost C p 、Installation cost C i , Operation and maintenance cost C o , B includes the potential savings brought by terminal deployment, that is, reducing the failure recovery time B f , reduce energy waste B e , the specific cost and benefit are: C = C p +C i +C o , B=B f +B e , introduce the profit increase ratio index I brought by unit cost, R j is the potential revenue of the jth region, S j is the power supply importance weight of the jth region, which can be determined based on factors such as load density and user satisfaction. j is the deployment cost of the jth region. Combined with the profit increase ratio index I, its economic benefit evaluation is E innovative=I×E, by comparing the profit increase ratio index I of different solutions, the most cost-effective option is screened out, the deployment of medium and low voltage terminals is optimized, the reliability and economy of the distribution network secondary system are ensured, the strategy is continuously optimized and adjusted, and differentiated zoning deployment is implemented.

[0093] Finally, formulate technical principles for planning and designing the secondary system of distribution networks for differentiated primary grids, and comprehensively integrate professional technical solutions such as grid control, fault handling, data collection, communication networking and safety protection.

[0094] Example 3

[0095] In specific implementation, the following methods can be used to analyze the characteristics of different power supply areas:

[0096] Defining the Differentiated Resilience Index R D The fault handling capability of each area is evaluated by quantitative calculation of the fault handling capability of each area. The formula is as follows:

[0097]

[0098] Where: k = 1, 2, .., N, N is the number of sampled scenes; i = 1, 2, .., T, T is the simulation duration; ΔT is the simulation step length; L i,k is the system load holding amount in the i-th simulation step under the k-th sampling scenario; L z is the total load of the system; L s,min,k is the minimum reserve of important loads in the kth sampling scenario; L s,z is the total amount of important load of the system; R re,k is the recovery speed index under the kth scenario; α is the weight of the recovery speed; using a coefficient of 0.5 can keep the resilience assessment result within a range;

[0099] R re,k Calculated by the following formula:

[0100]

[0101] Where f(t) is the recovery rate function at time t. Assuming that the power grid has different recovery rates at different recovery stages, f(t) is estimated using a piecewise linear model. The formula is as follows:

[0102]

[0103] where c1, c2…c n are different recovery rates at different recovery stages, c1, c2…c n It can be obtained by measurement;

[0104] The weight α can be adjusted according to the risk preferences and strategies of the grid operator.

[0105] Example 4

[0106] The formulation of technical principles includes the following aspects: the design of the secondary system of the distribution network should be based on existing mature technologies and actual on-site conditions, and should be appropriately advanced in view of future technological development trends, follow the principles of reliability, adaptability, and economy, and optimize the secondary system design and technical solutions. In terms of reliability, the design solution of the secondary system of the distribution network is required to have reliable information collection methods, information data channels, and control implementation methods; in terms of adaptability, the design solution of the secondary system of the distribution network is required to be compatible with the existing equipment and implementation conditions of the distribution system, and to minimize the impact on the operation of the existing distribution system and make full use of existing distribution equipment and other resources to avoid waste of resources caused by large-scale replacement; in terms of economy, the design of the secondary system of the distribution network is required to select economical configurations and implementation plans as much as possible on the premise of meeting reliability and adaptability, to avoid repeated investment or excessive communication operation costs;

[0107] Information flow: Under the premise of meeting the information bandwidth, measurement and control information use the same data channel for data exchange. The data flow is designed according to the communication method, and should meet the requirements of cloud-edge-end communication and end-end communication. It can meet the requirements of edge-edge communication. The information flow is designed according to the requirements of different information and different time scales to meet different business needs such as operation, monitoring, and measurement;

[0108] Control flow: The control flow design of the secondary system of the distribution station area should adopt the design principle of hierarchical control according to the different control time scales, and adopt the cloud, edge and end hierarchical control method. The control with a large time scale is carried out by the "cloud" side of the four-area master station, and the control with a smaller time scale is controlled by the lower-level "edge" (integrated terminal) or "end" (on-site controller) side. The real-time control with a small time scale is controlled by the "end" side equipment. Under the premise of meeting the information bandwidth, the measurement and control information should use the same data channel for data exchange. The data flow of the secondary system of the distribution station area should be designed according to the communication method, and should meet the requirements of cloud-edge-end communication and end-to-end communication. It can meet the requirements of edge-to-edge communication. The information flow should be designed according to the different time scale requirements of different information to meet different business needs such as operation, monitoring, and metering.

[0109] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for planning a secondary system of an active distribution network, characterized in that: The planning approach includes the following steps: S100, in-depth analysis of regional characteristics: in-depth analysis of key parameters such as short-circuit capacity, power supply radius, load rate, new energy access points and access capacity of each power supply area, forming a detailed regional characteristics database, evaluating the differentiated needs of each region for fault handling capabilities, and providing basic data support for subsequent differentiated configuration solutions; S200, formulation of differentiated fault handling configuration schemes: Analyze the electrical parameters of different power supply areas, evaluate the impact of new energy access points and their capacity, and design customized fault handling configuration schemes for different power supply areas; S300, Exploration of the function expansion and optimization path of medium and low voltage terminals: Based on the formulated differentiated configuration plan, clarify the functional requirements of low and medium voltage terminals in each region, develop terminal function expansions that adapt to the characteristics of different regions, and formulate differentiated step-by-step deployment strategies based on the full life cycle management theory to synchronize the terminals with regional development needs; S400, differentiated distribution terminal zoning deployment strategy: Combined with regional development planning, the differentiated configuration scheme is refined into specific zoning deployment strategies so that each region can obtain the most suitable distribution terminal configuration. Before implementation, economic benefit evaluation is carried out and the possibility of future expansion is considered; S500, formulation of technical principles for coordinated planning of primary and secondary systems: comprehensive integration of professional technical solutions such as power grid control, fault handling, data collection, communication networking and safety protection, and scientific formulation of technical principles for planning and design of distribution network secondary systems for differentiated primary grids.

2. According to claim 1, a method for planning a secondary system of an active distribution network is characterized in that: The specific steps of the S100 regional characteristics in-depth analysis for the impact assessment of new energy access and protection strategy design are as follows: Analysis of new energy access characteristics: Analyze the impact of new energy wind power and photovoltaic access on the fault characteristics of the distribution network, focusing on the changes in fault current and the diversity of fault types; Risk assessment and protection logic design: Assess the vulnerable points and risk areas of the distribution network after the integration of new energy, and design corresponding overcurrent protection and grounding protection logic; Timing logic and coordinated control: Design the timing logic between protection and backup automatic switching and reclosing safety automatic devices, and integrate the coordinated action strategy of new energy control devices and distribution automation systems, including anti-islanding protection strategy. The collaborative strategy design includes: Staged overcurrent protection: Design a multi-level protection strategy to ensure that the fault area can be quickly and accurately identified and isolated under different locations and types of loads and faults; Main transformer gap protection: Design special protection logic for internal faults of the main transformer to prevent the fault from expanding and causing damage; Reclosing optimization solution: When the instantaneous fault is eliminated, the circuit breaker is automatically reclosed to restore power supply; Automatic backup, that is, the backup power supply is automatically put into use: when the main power supply fails, it automatically switches to the backup power supply to ensure the continuous power supply of important loads; New energy anti-islanding protection: prevents the distributed energy system from continuing to supply power to the grid when a grid failure occurs, causing electric shock hazards to maintenance personnel and difficulties in grid restoration; Feeder automation device: Utilizes intelligent terminals and communication networks to automatically detect, locate and isolate faults, and quickly restore power supply to non-faulty areas.

3. According to claim 1, a method for planning a secondary system of an active distribution network is characterized in that: The S100 also includes a quantitative calculation of the fault handling capability of each region: defining the differentiated resilience index R D To evaluate the fault handling capability of each region, the formula is as follows: Where: k = 1, 2, .., N, N is the number of sampled scenes; i = 1, 2, .., T, T is the simulation duration; ΔT is the simulation step length; L i,k is the system load holding amount in the i-th simulation step under the k-th sampling scenario; L z is the total system load; L s,min,k is the minimum reserve of important loads in the kth sampling scenario; L s,z is the total amount of important load of the system; R re,k is the recovery speed index under the kth scenario; α is the weight of the recovery speed; using a coefficient of 0.5 can keep the resilience assessment result within a range; R re,k Calculated by the following formula: Where f(t) is the recovery rate function at time t. Assuming that the power grid has different recovery rates at different recovery stages, f(t) is estimated using a piecewise linear model. The formula is as follows: where c1, c2…c n are different recovery rates at different recovery stages, c1, c2…c n It can be obtained by measurement; The weight α can be adjusted according to the risk preferences and strategies of the grid operator.

4. The method for planning the secondary system of an active distribution network according to claim 1, characterized in that: The S200 differentiated fault handling configuration scheme is formulated based on the differences in the main distribution network, and an overall configuration scheme and a differentiated design scheme for active distribution network fault handling are proposed to meet the specific needs of different power supply areas. The specific steps are as follows: S201, power supply area characteristics analysis: collect and analyze in detail the electrical parameters of different power supply areas and new energy access points and their capacities, and determine the key performance indicators of each power supply area; S202, fault handling configuration analysis: based on the collected data, analyzing the fault characteristics of different power supply areas, including fault type, frequency and duration; S203, formulation of differentiated configuration schemes: design specific fault handling configuration schemes according to the characteristics of the power supply area, including adjusting protection settings, optimizing equipment layout and adding intelligent control units, evaluating the economic and feasibility of different configuration schemes, and formulating emergency response plans, including fault early warning, rapid isolation and automatic recovery strategies; S204, solution implementation and verification: Implement differentiated fault handling configuration solutions in the power supply area, and conduct simulation tests and field trials.

5. The method for planning the secondary system of an active distribution network according to claim 1, characterized in that: The specific steps of S300 are: S301, Current Status Analysis and Functional Evaluation: Detailed analysis of the functions of existing medium and low voltage terminals and edge IoT agents, including basic functions of data collection, status monitoring, remote control and fault diagnosis, and evaluation of terminal performance indicators, including data transmission rate, power consumption, storage capacity, and computing power; S302, Demand forecasting and scenario construction: Based on the grid development plan and future demand forecast, different usage scenarios are constructed, including: high-density residential areas, industrial areas, commercial areas, rural areas, and load management, distributed energy access, and electric vehicle charging facility support; S303, cluster analysis and functional requirement matching: use clustering technology to classify medium and low voltage terminals, and classify the terminals into different categories according to their functional characteristics and application scenarios; S304, function expansion path planning: based on the results of cluster analysis, plan the optimal path for function expansion, which involves hardware upgrades, software updates, and development of new function modules; S305, Economic Benefit Analysis: Estimate the cost of each functional expansion plan, including direct and indirect costs, and evaluate the economic benefits that the expanded terminal can bring, including reducing operation and maintenance costs, improving service quality, and increasing user satisfaction.

6. The method for planning the secondary system of an active distribution network according to claim 1, characterized in that: The active power distribution secondary system is used to implement all technologies and equipment for power grid monitoring, control, protection and automation functions, including components: Distribution network protection device: used to detect grid faults and quickly act to isolate the faulty area; Safety automatic device: Automation equipment used to automatically implement safety measures, i.e. automatic reclosing of circuit breakers; New energy control system: manage and control new energy resources connected to the power grid to ensure their stable integration into the grid; Distribution Automation System (DAS): An integrated automation system that monitors and controls the operation of the distribution network, improving response speed and efficiency; Communication systems: including communication technology, data transmission and information exchange between systems; Data acquisition system: collects power grid operation data to provide support for analysis and decision-making; Security protection system: Cybersecurity and physical security of the power grid to prevent malicious attacks and unauthorized access.

7. The method for planning the secondary system of an active distribution network according to claim 5, characterized in that: The cluster analysis and function requirement matching in S303 utilizes clustering technology to explore the function expansion and optimization paths of medium and low voltage terminals. The medium and low voltage terminals include trunk line terminals, protection configuration terminals, branch terminals and user terminals. For the medium and low voltage terminal T, that is, T = (t1, t2, ..., t n }, where each terminal t i Represented as a feature vector X i =[x i1 , x i2 , ..., x im ], m is the number of features, for the set of application scenarios S = {s1, s2, ..., s k }, each scene s j There is a corresponding weight W j , define terminal t i and scenes j The distance between D ij It is the terminal i and scenes j The distance between jl It's scenes j The weight of feature l, μ jl It's scenes j The average value of feature l in , based on the distance metric, the objective function of the clustering problem is defined as Find C = {C1, C2, ..., C k }, so that j is the smallest, where C j Belongs to scenes j After clustering, the functional expansion direction and priority of each category are determined based on the common functional characteristics of the terminals in each category.

8. The method for planning the secondary system of an active distribution network according to claim 1, characterized in that: The specific steps of S400 are: S401, demand collection and analysis: collect detailed information on different power supply areas, including geographical distribution, load characteristics, network structure, and new energy access, and analyze the specific needs of these areas for distribution terminals, including data collection frequency, communication bandwidth, and real-time control capabilities; S402, regional classification: classify the power supply areas according to their similarities, and the classification basis includes but is not limited to power supply radius, load type, user density, and new energy penetration rate; S403, Strategy formulation: Design a specific distribution terminal deployment strategy for each type of power supply area. The strategy takes into account the type, quantity, location of the terminal and the design of the communication network. For commercial areas with high load density, higher performance terminals and stronger communication capabilities are used. For remote agricultural areas, more attention is paid to the reliability and low maintenance requirements of the terminal. S404, Economic Benefit Assessment: Conduct a cost-benefit analysis for each deployment strategy, including terminal procurement cost, installation cost, operation and maintenance cost, and potential savings, i.e., total cost including reduced fault recovery time and reduced energy waste. The long-term economic benefits of each strategy are obtained through the life cycle cost assessment model LCC. S405, strategy optimization and adjustment: Based on the results of the economic benefit evaluation, the initially formulated strategy is optimized and adjusted, and repeated iterations are performed to find the deployment solution with the highest cost-effectiveness ratio; S406, implementation and monitoring: execute the finalized differentiated partition deployment strategy. During the implementation process, establish a monitoring mechanism, regularly collect terminal operation data, and evaluate the actual effect of the strategy so as to make timely adjustments and optimizations.

9. The method for planning the secondary system of an active power distribution network according to claim 8, characterized in that: The S401 economic benefit evaluation is used to analyze and optimize the functional expansion and deployment strategies of medium and low voltage terminals, identify the solution that minimizes the total cost, and consider the economic benefits and return on investment, including the total cost C, the total income B, and the economic benefit E. C includes terminal purchase cost C p 、Installation cost C i , Operation and maintenance cost C o , B includes the potential savings brought by terminal deployment, that is, reducing the failure recovery time B f , reduce energy waste B e , the specific cost and benefit are: C = C p +C i +C o , B=B f +B e , introduce the profit increase ratio indicator I brought by unit cost, R j is the potential revenue of the jth region, S j is the power supply importance weight of the jth region, which can be determined based on factors such as load density and user satisfaction. j is the deployment cost of the jth region. Combined with the profit increase ratio index I, its economic benefit evaluation is E innovative =I×E, through calculation, the cost of each functional expansion plan is accurately estimated, including direct costs such as hardware procurement and software development, as well as indirect costs such as training and maintenance, and the economic benefits that the expanded terminal can bring are comprehensively evaluated to determine the most ideal expansion strategy.

10. The method for planning a secondary system of an active power distribution network according to claim 1, characterized in that: The system also studies the transient characteristics of fault traveling waves when different types of faults occur, the generation, propagation and attenuation characteristics of traveling waves in the distribution network, collects traveling wave signal data under different fault conditions, including parameters of waveform, frequency and amplitude, analyzes and processes traveling wave signals to extract key information required for fault detection, designs distribution terminal devices for real-time collection and processing of traveling wave signals, integrates fault detection into the distribution terminal devices, and tests them in actual distribution network environments, evaluates the fault detection speed, accuracy and reliability of the devices, optimizes them based on the test results, and formulates deployment strategies for distribution terminal devices, including the number, location and maintenance plans of the devices.

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