A method for secondary system planning of an active distribution network

Abstract

The present invention discloses a method for planning the secondary system of an active distribution network, which relates to the technical field of power system planning. The planning method includes the following steps: in-depth analysis of regional characteristics, formulation of a differential fault handling configuration scheme, exploration of the expansion and optimization path of the functions of medium and low voltage terminals, differential distribution terminal zoning deployment strategy, formulation of the overall planning technical principle for the primary and secondary systems, and scientifically formulating the planning and design technical principle for the secondary system of the distribution network facing the differential primary grid. Through the careful analysis of the impact of new energy access, the present invention designs targeted protection logic and cooperative control strategies, which can accurately identify and quickly isolate the fault area under different positions and types of loads, reduce the power outage time of users in the non-fault area, and through the implementation of the differential zoning deployment strategy, each power supply area can obtain the distribution terminal configuration most suitable for its own needs, further enhancing the fault handling ability.

Description

Technical Field

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

[0002] With the transformation of the energy structure and the promotion of sustainable development, the penetration rate of new energy in the power system is continuously increasing. As an important part of the power system, the active distribution network not only needs to accept the electric energy of traditional energy sources but also adapt to the access of new energy sources, such as distributed energy sources like wind energy and solar energy. This high-penetration access of new energy poses 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 for ensuring the safe, stable, and economic operation of the power grid.

[0003] However, the existing methods for planning the secondary system of the distribution network fail to fully consider the characteristics of different power supply areas, such as the differences in key parameters like short-circuit capacity, power supply radius, load rate, new energy access points, and access capacity. This results in the difficulty of accurately adapting the fault handling configuration scheme to the needs of each area and the inability to achieve refined management of the fault handling strategy. In terms of differential deployment, the existing technologies ignore the differential requirements of different power supply areas for distribution terminals and fail to carry out reasonable zonal deployment in combination with the regional development plan, leading to unreasonable resource allocation, over-investment in some areas, and insufficient equipment in other areas with higher demands, affecting power supply reliability and service quality.

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

[0005] The purpose of the present invention is to make up for the deficiencies of the existing technology and provide a method for planning the secondary system of 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 fault handling coordination cooperation scheme, and more precisely control the fault handling process through the coordination cooperation scheme of stage overcurrent protection and main transformer gap protection, reduce the interference to the power grid operation, and improve the adaptability of the power grid to the volatility of new energy.

[0006] To solve the above technical problems, the present invention provides the following technical solution: A method for planning the secondary system of an active distribution network, the planning method includes the following steps:

[0007] S100, In-depth analysis of regional characteristics: Deeply analyze the key parameters of short-circuit capacity, power supply radius, load rate, new energy access points and access capacity in each power supply area, form a detailed regional characteristics database, evaluate the different requirements of each area for fault handling capabilities, and provide basic data support for subsequent differential configuration schemes;

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

[0009] S300, Exploration of function expansion and optimization paths for medium- and low-voltage terminals: Based on the differential configuration scheme, clarify the function requirements of medium- and low-voltage terminals in each area, develop terminal function expansions adapted to different regional characteristics, and formulate differential step-by-step deployment strategies based on the theory of full life cycle management to synchronize the terminals with the development needs of the area;

[0010] S400, Differential distribution terminal zoning deployment strategy: Combine the regional development plan, refine the differential configuration scheme into specific zoning deployment strategies, enable each area to obtain the most suitable distribution terminal configuration, conduct economic benefit evaluation before implementation, and consider the possibility of future expansion;

[0011] S500, Formulation of technical principles for overall planning of primary and secondary systems: Comprehensively integrate professional technical solutions such as power grid regulation, fault handling, data acquisition, communication networking, and security protection, and scientifically formulate technical principles for the planning and design of the secondary system of the distribution network for the differential primary grid.

[0012] Furthermore, the specific steps of the S100 in-depth analysis of regional characteristics for the evaluation of the impact of new energy access and the design of protection strategies 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, and focus on studying the changes in fault current and the diversity of fault types;

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

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

[0016] The design of the coordinated cooperation strategy plan includes:

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

[0018] Main transformer gap protection: For internal faults occurring in the main transformer, design a dedicated protection logic to prevent damage caused by the expansion of the fault;

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

[0020] BATS, that is, backup power automatic input strategy: When the main power supply fails, it automatically switches to the backup power supply to ensure continuous power supply for important loads;

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

[0022] Feeder automation device: Utilize intelligent terminals and communication networks to achieve automatic detection, location, and isolation of faults, and quickly restore power supply to non-fault areas.

[0023] Furthermore, the S100 also includes a quantitative calculation of the fault handling capabilities of each region: Define a differential resilience index R D to evaluate the fault handling capabilities of each region. The formula is as follows:

[0024]

[0025] where: k = 1, 2,.., N, N is the number of sampling scenarios; i = 1, 2,.., T, T is the simulation duration; ΔT is the simulation step size; L i,k is the system load retention 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 retention of important loads under the k-th sampling scenario; L s,z is the total amount of important loads in the system; R re,k is the recovery speed index under the k-th scenario; α is the weight of the recovery speed; Using a coefficient of 0.5 can control the resilience evaluation results within a certain range;

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

[0027]

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

[0029]

[0030] Among them, c1, c2... c n are different recovery rates at different recovery stages, and c1, c2... c n can be obtained through measurement;

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

[0032] Furthermore, the formulation of the S200 differential fault handling configuration scheme proposes an overall configuration scheme and a differential design scheme for active distribution network fault handling according to the differences between the main and distribution networks to meet the specific needs of different power supply areas. The specific steps are as follows:

[0033] S201, Analysis of power supply area characteristics: Collect and analyze in detail the electrical parameters of different power supply areas, as well as the 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, analyze the fault characteristics of different power supply areas, including fault types, frequencies, and durations;

[0035] S203, Formulation of differential configuration scheme: According to the characteristics of the power supply area, design a specific fault handling configuration scheme, including adjusting protection settings, optimizing equipment layout, and adding intelligent control units, evaluate the economy and feasibility of different configuration schemes, and formulate an emergency response plan, including fault warning, rapid isolation, and automatic recovery strategies;

[0036] S204, Scheme implementation and verification: Implement the differential fault handling configuration scheme in the power supply area and conduct simulation tests and on-site trials.

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

[0038] S301, Current situation analysis and function evaluation: Conduct a detailed analysis of the functions of existing medium and low voltage terminals and edge IoT agents, including the basic functions of data acquisition, status monitoring, remote control, and fault diagnosis, and evaluate the terminal performance indicators, including data transmission rate, power consumption, storage capacity, and computing power;

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

[0040] S303, Cluster Analysis and Function Requirement Matching: Use clustering techniques 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 upgrade, software update, and the development of new function modules;

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

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

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

[0045] Safety automatic device: An automated device used to automatically execute safety measures, that is, the automatic reclosing of circuit breakers;

[0046] New energy control system: Manage and control new energy resources connected to the 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 to improve response speed and efficiency;

[0048] Communication system: Includes communication technologies, data transmission, and information exchange between systems;

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

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

[0051] Furthermore, medium- and low-voltage lines should be equipped with circuit breakers, grid terminals and other equipment at the cable line main trunk line inlets and outlets, overhead line main trunk line sections and branches, user demarcation points, reactive power compensation and other positions according to the requirements of fault handling and dispatching control. The application of integrated primary and secondary pole-mounted switches is promoted for overhead lines. The S303 cluster analysis and function requirement matching uses clustering techniques for the function expansion and optimization path exploration of medium- and low-voltage terminals. The medium- and low-voltage terminals include main 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 is represented as a feature vector Xi = x i1 , x i2 , …, x im , where m is the number of features. For the set of application scenarios S = {s1, s2, …, s k}, each scenario s j has a corresponding weight W j . Define the distance i between the terminal t j and the scenario s D ij as the distance between the terminal t i and the scenario s j . Let w jl be the weight of the scenario s j for the feature l, and μ jl be the average value of the feature l in the scenario s j . Based on the distance metric, the objective function of the clustering problem is defined as Find C = {C1, C2, …, C k} such that j is minimized, where C j is the set of terminals belonging to the scenario s j . After completing the clustering, determine the function expansion direction and priority of each category according to the functional characteristics shared by the terminals in each category.

[0052] Further, the specific steps of S400 are as follows:

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

[0054] S402, Region classification: Classify the power supply areas according to their similarity, 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 specific distribution terminal deployment strategies for each category of power supply areas. The strategies consider the type, quantity, location of the terminals and the design of the communication network. For commercial areas with high load density, use higher-performance terminals and stronger communication capabilities. For remote agricultural areas, pay more attention to the reliability of the terminals and low maintenance requirements;

[0056] S404, Economic benefit evaluation: Conduct a cost-benefit analysis for each deployment strategy. The evaluation includes the total cost of terminal procurement cost, installation cost, operation and maintenance cost, and potential savings, that is, the total cost including reducing the fault recovery time and reducing energy waste. Through the life cycle cost evaluation model LCC, obtain the long-term economic benefits of each strategy;

[0057] S405, Strategy Optimization and Adjustment: According to the results of economic benefit evaluation, optimize and adjust the initially formulated strategy, iterate repeatedly to find the deployment plan with the highest cost-benefit ratio;

[0058] S406, Implementation and Monitoring: Implement the finally determined differential zoning deployment strategy. During the implementation process, establish a monitoring mechanism, regularly collect terminal operation data, and evaluate the actual effect of the strategy to facilitate timely adjustment and optimization.

[0059] Furthermore, the S401 economic benefit evaluation is used to analyze and optimize the function expansion and deployment strategy of medium and low voltage terminals, identify the plan that minimizes the total cost, and consider economic benefits and return on investment. Including the total cost C, total revenue B, and economic benefit E, then C includes the terminal procurement cost C p and the installation cost C i and the operation and maintenance cost C o ; B includes the potential savings brought by terminal deployment, that is, reducing the fault recovery time B f and reducing energy waste B e , the specific costs and revenues are: C = C p + C i + C o , B = B f + B e . Introduce the index I of the increased revenue ratio brought by unit cost. R j is the potential revenue of the j-th area, S j is the power supply importance weight of the j-th area, which can be determined according to factors such as load density and user satisfaction. C j is the deployment cost of the j-th area. Combining with the increased revenue ratio index I, its economic benefit evaluation is E innovative = I × E. Accurately estimate the cost of each function expansion plan through calculation, including direct costs such as hardware procurement and software development, and indirect costs such as training and maintenance. Comprehensively evaluate the economic benefits that the expanded terminal can bring, so as 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 such as waveform, frequency, and amplitude, analyzes and processes the traveling wave signals to extract the key information required for fault detection, designs a distribution terminal device for real-time acquisition and processing of traveling wave signals, integrates fault detection into the distribution terminal device, and conducts tests in the actual distribution network environment to evaluate the fault detection speed, accuracy, and reliability of the device, and optimizes according to the test results, formulates a deployment strategy for the distribution terminal device, including the number, location, and maintenance plan of the device.

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

[0062] First, through a detailed analysis of the impact of new energy access, the present invention designs targeted protection logics and coordinated control strategies, which can accurately identify and quickly isolate the fault area under different positions and types of loads, avoid the spread of faults, and reduce the power outage time of users in non-fault areas;

[0063] Second, according to the functional expansion and optimization path of the distribution terminal, the present invention clarifies the functional requirements of the terminal, develops a terminal functional expansion scheme suitable for different regional characteristics, synchronizes the terminal with the regional development needs, improves the flexibility and adaptability of the terminal, and through the implementation of a differential zoning deployment strategy, each power supply area can obtain the distribution terminal configuration most suitable for its own needs, further enhancing the fault handling ability;

[0064] Third, by defining differential resilience indicators to quantitatively calculate the fault handling capabilities of each region, the evaluation results are more objective and accurate, can analyze the specific conditions of each region in more detail, and comprehensively consider multiple factors such as system load retention, minimum retention of important loads, and restoration speed during calculation, introduce the weight of the restoration speed, increase the flexibility and accuracy of the evaluation, and can guide the optimal allocation of resources in different regions through the evaluation results, improve the resilience and reliability of the overall system, better prepare for and respond to possible emergencies, and reduce the impact of faults on the system;

[0065] Fourth, through a detailed in-depth analysis of regional characteristics, the present invention accurately evaluates the requirements of each power supply area for fault handling capabilities, and accordingly formulates a differential fault handling configuration plan. This method avoids the one-size-fits-all configuration method in all regions, but flexibly adjusts the protection settings and optimizes the equipment layout according to the characteristics of different regions, ensuring the effective utilization of resources;

[0066] V. The present invention comprehensively considers multiple dimensions such as the terminal procurement cost, installation cost, operation and maintenance cost, and potential savings, accurately calculates the long-term economic benefits of each deployment strategy, helps to select the plan with the highest cost-effectiveness ratio, improves the resource utilization efficiency, reduces the overall cost, increases the economic benefits of the power company, and at the same time provides more cost-effective services for users.

[0067] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0069] Figure 1 It is an operation flowchart of a method for planning the secondary system of an active distribution network.

[0070] Figure 2 It is a flowchart of the steps of a method for formulating a S200 differential fault handling configuration plan. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0072] Embodiment 1

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

[0074] First, enter the stage of the fault handling coordination plan (S100), analyze the impact of new energy access (such as wind power, photovoltaic) on the fault characteristics of the distribution network, including the change of fault current and the diversity of fault types, evaluate the vulnerable points and risk areas after high-penetration 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, specifically including:

[0075] Step-overcurrent protection: Design a multi-stage protection strategy to ensure the quick and accurate identification and isolation of the fault area;

[0076] Main transformer gap protection: Design a protection logic for internal faults of the main transformer to prevent the expansion of faults;

[0077] Reclosing optimization: Automatically reclosing the circuit breaker to restore power supply for instantaneous faults;

[0078] Standby power supply automatic switching strategy: Automatically switch to the standby power supply to ensure the power supply of important loads;

[0079] New energy anti-islanding protection: Prevent the distributed energy system from continuing to supply power during grid faults and avoid potential safety hazards;

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

[0081] Then, enter the stage of formulating a differential fault handling configuration plan (S200). Comprehensively collect characteristic data such as short-circuit capacity, power supply radius, load rate, new energy access points and access capacity in different power supply areas, and conduct 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 types, occurrence frequencies, and durations. At the same time, deeply explore the performance bottlenecks and adaptability of existing fault handling equipment. According to the unique characteristics of the power supply area, creatively design exclusive fault handling configuration plans, such as flexibly adjusting protection settings, scientifically optimizing equipment layouts, and reasonably adding intelligent control units. Comprehensively evaluate the economic efficiency and feasibility of different configuration plans, and carefully formulate a complete emergency response plan, including accurate fault early warning, efficient rapid isolation, and intelligent automatic recovery strategies. Steadily implement the differential fault handling configuration plan in the selected power supply area, conduct rigorous simulation tests and on-site experiments, and comprehensively verify the effectiveness and safety of the plan. Precisely adjust the plan according to the test results to effectively ensure the ability to handle various complex fault situations in actual operation. Develop detailed implementation rules, covering aspects such as equipment configuration, parameter setting, operation procedures, and maintenance guidelines, to effectively ensure the efficient implementation of the differential design plan. For areas with a high load rate, the configuration of standby power supply equipment can be increased, and protection settings can be optimized to improve the response speed. Simulation tests can simulate various extreme fault situations, such as the occurrence of multiple faults simultaneously or the situation when the new energy output fluctuates greatly, to test the reliability of the plan.

[0082] Next, enter the stage of exploring the path for expanding and optimizing the functions of medium- and low-voltage terminals (S300). 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. 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, carefully construct diverse usage scenarios, such as high-density residential areas, industrial areas, commercial areas, and rural areas. Fully consider the specific needs in each scenario, such as load management, distributed energy access, and support for electric vehicle charging facilities. Conduct a detailed classification of medium- and low-voltage terminals, and classify the terminals into different categories according to their functional characteristics and application scenarios. For the specific needs of each category, clarify the direction and priority of function expansion. Based on the results of cluster analysis, scientifically plan the optimal path for function expansion, involving hardware upgrading and transformation, software update, and careful development of new function modules. Accurately estimate the cost of each function expansion plan, including direct costs such as hardware procurement and software development, as well as indirect costs such as training and maintenance. Comprehensively evaluate the economic benefits that can be brought by the expanded terminals.

[0083] Subsequently, enter the stage of differentiated distribution terminal zoning deployment strategy (S400). Combining with the regional development plan, further refine the differentiated configuration plan into specific zoning deployment strategies. Before implementation, conduct a comprehensive economic benefit assessment of this strategy, fully considering the possibility of future expansion to ensure that each region can obtain the most suitable distribution terminal configuration.

[0084] Finally, enter the stage of fault traveling wave transient characteristics (S500). Integrate professional technical solutions such as power grid regulation and control, fault handling, data acquisition, communication networking, and security protection. Scientifically formulate technical principles for the secondary system planning and design of the distribution network facing the differentiated primary grid framework to ensure the 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 a distribution terminal device for real-time acquisition and processing of traveling wave signals, test the device in the actual distribution network environment, evaluate the fault detection speed, accuracy, and reliability, and formulate technical principles for the secondary system planning and design of the distribution network facing the differentiated primary grid framework.

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

[0086] Embodiment 2

[0087] This embodiment aims to describe in detail a method for secondary system planning of an active distribution network. By clustering and analyzing the characteristics of different power supply areas, achieve refined management of fault handling strategies, quickly and accurately identify and isolate power grid faults, and use economic benefit assessment to optimize resource allocation, improving the economy and reliability of power grid operation.

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

[0089] Taking the typical grid structure of medium-voltage distribution network overhead lines as an example, the substation outlet intervals CX1 and CX2 are usually equipped with perfect protection functions and primary equipment, that is, integrated protection and measurement devices, and no upgrade and transformation work is required; the main line section intervals include FD1, FD2, FD, FD3, FD4, and integrated primary and secondary pole-mounted switches (including FTU, circuit breaker, voltage transformer, current transformer, 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, Sub-branch 3, and integrated primary and secondary pole-mounted switches should be installed according to the protection configuration requirements. If there is no protection configuration requirement, the status quo can be maintained; for the user demarcation intervals, including PB1, PB4, PB5, PB2, PB3, PB6, integrated primary and secondary pole-mounted switches should be configured and installed; for the shunt-type reactive power compensation intervals, integrated primary and secondary pole-mounted switches should be configured and installed; the fault indicators should be selected and installed at appropriate positions in combination with the requirements of accurate fault location;

[0090] Urban cable lines mainly use ring main units to realize the connection of cable inlets and outlets, that is, the substation outgoing cable line 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 converge to the busbar of the ring main unit, and the ring main units are connected through the outgoing cable line (liaison line). Taking this grid structure as an example, the substation outlet intervals CX1 and CX2 are usually equipped with perfect protection functions and primary equipment, and no upgrade and transformation work is required; the main line incoming intervals include HW11, HW12, HW21, HW22, HW31, HW32, and 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 intervals include hw11, hw12, hw13, hw21, hw22, hw23, hw31, hw32, hw33, and 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; for the user demarcation intervals, integrated primary and secondary pole-mounted switches should be configured and installed.

[0091] Then, deeply analyze the functions of existing medium and low-voltage terminals and IoT agents, evaluate their performance indicators, and based on the whole life cycle theory, conduct cluster analysis, collect relevant data of medium and low-voltage terminals, including characteristics such as computing power, deployment cost, communication requirements, and maintainability, select and construct feature vectors to accurately represent the key attributes of the terminals. For the medium and low-voltage terminal T, that is, T = {t1, t2, …, t n}, where each terminal t i is represented as a feature vector X i = [x i1 , x i2 , …, x im, where m is the number of features. For the set of application scenarios S = {s1, s2, …, s k}, each scenario s j has a corresponding weight W j . Define the distance i between the terminal t j and the scenario s as D ij . D i is the distance between the terminal t j and the scenario s jl . w j is the weight of the scenario s jl for the feature l, μ j is the average value of the feature l in the scenario s . Find C = {C1, C2, …, C k} such that j is minimized, where C j is the set of terminals belonging to the scenario s j . Evaluate the clustering result, determine whether the expected clustering effect is satisfied, and adjust the functional expansion path of the terminal according to the clustering result, plan the hardware upgrade and software development to achieve the effective expansion of the terminal function.

[0092] Subsequently, comprehensively collect and analyze the differentiated requirements of different power supply areas, formulate and evaluate the economic benefits of the zoning deployment strategy, and consider the economic benefits and return on investment, including the total cost C, the total revenue B, and the economic benefit E. Then C includes the terminal procurement cost C p , the installation cost C i , and the operation and maintenance cost C o . B includes the potential savings brought by the terminal deployment, that is, reducing the fault recovery time B f and reducing energy waste B e . The specific costs and revenues are: C = C p + C i + C o , B = B f + B e . Introduce the index I of the increase ratio of the revenue brought by the unit cost. R j is the potential revenue of the j-th area, S j is the power supply importance weight of the j-th area, which can be determined according to factors such as load density and user satisfaction. C j is the deployment cost of the j-th area. Combining the index I of the increase ratio of the revenue, its economic benefit evaluation is E innovative= I × E. By comparing the income increase ratio index I of different solutions, the most cost-effective option is selected to optimize the deployment of medium and low voltage terminals, ensure the reliability and economy of the secondary system of the distribution network, continuously optimize and adjust the strategy, and implement differential zoning deployment.

[0093] Finally, formulate the technical principles for the planning and design of the secondary system of the distribution network for the differential primary grid framework, and comprehensively integrate professional technical solutions such as power grid regulation, fault handling, data acquisition, communication networking, and security protection.

[0094] Example 3

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

[0096] Define the differential resilience index R D Quantitatively calculate the fault handling capabilities of each area to evaluate the fault handling capabilities of each area. The formula is as follows:

[0097]

[0098] Where: k = 1, 2,.., N, N is the number of sampling scenarios; i = 1, 2,.., T, T is the simulation duration; ΔT is the simulation step size; L i,k is the system load retention 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 retention of important loads under the k-th sampling scenario; L s,z is the total amount of important loads in the system; R re,k is the recovery speed index in the k-th scenario; α is the weight of the recovery speed; Using the coefficient 0.5 can control the resilience evaluation result within a range;

[0099] R re,k It is calculated by the following formula:

[0100]

[0101] Where f(t) is the recovery rate function of time t. Assuming that the power grid has different recovery rates in 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 the different recovery rates in different recovery stages, c1, c2…c n can be obtained by measurement;

[0104] This weight α can be adjusted according to the risk preference and strategy of the power 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 secondary system planning of an active distribution network, characterized in that The planning method includes the following steps: S100, in-depth analysis of regional characteristics: Deeply analyze the key parameters of short-circuit capacity, power supply radius, load rate, new energy access points and access capacity in each power supply area, form a detailed regional characteristics database, evaluate the differentiated requirements of each area for fault handling capabilities, and provide basic data support for subsequent differentiated configuration schemes; 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 capacities, and design customized fault handling configuration schemes for different power supply areas; S300, exploration of the path for function expansion and optimization of medium- and low-voltage terminals: Based on the formulated differentiated configuration scheme, clarify the function requirements of medium- and low-voltage terminals in each area, develop terminal function expansions adapted to different regional characteristics, and formulate a differentiated step-by-step deployment strategy based on the theory of full life cycle management to synchronize the terminals with the regional development requirements; S400, differentiated distribution terminal zoning deployment strategy: Combine the regional development plan, refine the differentiated configuration scheme into a specific zoning deployment strategy, so that each area can obtain the most suitable distribution terminal configuration, conduct an economic benefit assessment before implementation, and consider the possibility of future expansion; S500, formulation of technical principles for overall planning of primary and secondary systems: Comprehensively integrate professional technical solutions such as power grid regulation, fault handling, data acquisition, communication networking, and security protection, and scientifically formulate technical principles for the secondary system planning and design of the distribution network facing the differentiated primary grid framework; The S100 also includes a quantitative calculation of the fault handling capabilities of each region: Define a differential resilience index R D to evaluate the fault handling capabilities of each region. The formula is as follows: Where: k = 1, 2,.., N, N is the number of sampling scenarios; i = 1, 2,.., T, T is the simulation duration; ΔT is the simulation step size; L i,k is the system load retention during the i-th simulation step in the k-th sampling scenario; L z is the total system load; L s,min,k is the minimum retention of important loads in the k-th sampling scenario; L s,z is the total amount of important loads in the system; R re,k is the recovery speed index in the k-th scenario; α is the weight of the recovery speed; Using the coefficient 0.5 can control the resilience assessment results within a range; R re,k Calculated by the following formula: Where f(t) is the recovery rate function of time t. Assuming that the power grid has different recovery rates in different recovery stages, f(t) is estimated using a piecewise linear model, and the formula is as follows: where c1, c2... c n are different recovery rates for different recovery stages, and c1, c2... c n can be obtained by measurement; This weight α can be adjusted according to the risk preference and strategy of the grid operator.

2. The method for planning the secondary system of an active distribution network according to claim 1, wherein The specific steps of the in-depth analysis of regional characteristics in S100 for the impact assessment of new energy access and the design of protection strategies 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, and focus on studying the changes in fault current and the diversity of fault types; Risk assessment and protection logic design: Evaluate the vulnerable points and risk areas of the distribution network after new energy access, and design corresponding overcurrent protection and grounding protection logics; Sequential logic and coordinated control: Design the sequential logic between protection, standby power automatic input, and reclosing safety automatic devices, and integrate the coordinated action strategies of new energy control devices and distribution automation systems, including anti-islanding protection strategies; The design of the coordinated cooperation strategy plan includes: Staged overcurrent protection: Design a multi-level protection strategy to ensure that fault areas can be quickly and accurately identified and isolated under different positions, types of loads and faults; Main transformer gap protection: Design a special protection logic for internal faults occurring in the main transformer to prevent damage caused by the expansion of faults; Reclosing optimization scheme: When instantaneous faults are eliminated, automatically reclose the circuit breaker to restore power supply; Standby power automatic input, that is, the standby power automatic input strategy: When the main power supply fails, automatically switch to the standby power supply to ensure continuous power supply for important loads; New energy anti-islanding protection: prevent the distributed energy system from continuing to supply power to the grid during grid faults, causing electric shock hazards to maintenance personnel and difficulties in grid restoration; Feeder automation device: utilize intelligent terminals and communication networks to achieve automatic detection, location, and isolation of faults, and quickly restore power supply to non-fault areas.

3. The method for planning the secondary system of an active distribution network according to claim 1, wherein The formulation of the S200 differential fault handling configuration scheme is based on the differences between the main and distribution networks, and proposes an overall configuration scheme and a differential design scheme for active distribution network fault handling to meet the specific requirements of different power supply areas. The specific steps are as follows: S201, Analysis of power supply area characteristics: collect and analyze in detail the electrical parameters of different power supply areas, as well as the new energy access points and their capacities, and determine the key performance indicators of each power supply area; S202, Analysis of fault handling configuration: based on the collected data, analyze the fault characteristics of different power supply areas, including fault types, frequencies, and durations; S203, Formulation of differential configuration scheme: according to the characteristics of the power supply area, design specific fault handling configuration schemes, including adjusting protection settings, optimizing equipment layout, and adding intelligent control units, evaluate the economy and feasibility of different configuration schemes, and formulate an emergency response plan, including fault warning, rapid isolation, and automatic restoration strategies; S204, Scheme implementation and verification: implement the differential fault handling configuration scheme in the power supply area and conduct simulation tests and on-site experiments.

4. The method for planning the secondary system of an active distribution network according to claim 1, wherein The specific steps of S300 are as follows: S301, Current situation analysis and function evaluation: conduct a detailed analysis of the functions of existing medium and low voltage terminals and edge IoT agents, including basic functions such as data collection, status monitoring, remote control, and fault diagnosis, and evaluate the terminal performance indicators, including data transmission rate, power consumption, storage capacity, and computing power; S302, Demand prediction and scenario construction: based on the grid development plan and future demand prediction, construct different usage scenarios, including high-density residential areas, industrial areas, commercial areas, and rural areas, and support load management, distributed energy access, and electric vehicle charging facilities; S303, Cluster analysis and function requirement matching: use clustering technology to classify medium and low voltage terminals, and classify the terminals into different categories according to their function characteristics and application scenarios; S304, Function expansion path planning: based on the results of cluster analysis, plan the optimal path for function expansion, involving hardware upgrades, software updates, and the development of new function modules; S305, Economic benefit analysis: estimate the costs of each function expansion scheme, including direct costs and indirect costs, and evaluate the economic benefits that can be brought by the expanded terminals, including reducing operation and maintenance costs, improving service quality, and increasing user satisfaction.

5. The method for planning the secondary system of an active distribution network according to claim 1, wherein The active distribution secondary system is used for all technologies and equipment to achieve grid monitoring, control, protection, and automation functions, and includes the following components: Distribution network protection device: used to detect grid faults and quickly act to isolate the fault area; Safety automatic device: an automatic device used to automatically execute safety measures, that is, the automatic reclosing of circuit breakers; New energy control system: manage and control new energy resources connected to the 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, enhancing response speed and efficiency; Communication System: Includes communication technologies, data transmission, and information exchange between systems; Data Acquisition System: Collects power grid operation data to support analysis and decision-making; Security Protection System: Ensures the network security and physical security of the power grid, preventing malicious attacks and unauthorized access.

6. The method for planning a secondary system of an active distribution network according to claim 4, characterized in that, The S303 clustering analysis and function requirement matching uses clustering technology to explore the function expansion and optimization path for medium and low voltage terminals. The medium and low voltage terminals include main 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 is 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 scenario s j has a corresponding weight W j . Define the distance i between the terminal t j and the scenario s D ij is the distance between the terminal t i and the scenario s j . w jl is the weight of the scenario s j for the feature l, and μ jl is the average value of the feature l in the scenario s j . Based on the distance metric, the objective function of the clustering problem is defined as Find C = {C1, C2, …, C k} such that j is minimized, where C j is the set of terminals belonging to the scenario s j . After completing the clustering, determine the function expansion direction and priority of each category according to the common functional characteristics of the terminals in each category.

7. The method for planning the secondary system of an active distribution network according to claim 1, wherein The specific steps of S400 are as follows: S401, Requirement Collection and Analysis: Collect detailed information on different power supply areas, including geographical distribution, load characteristics, network structure, and new energy access conditions. Analyze the specific requirements for distribution terminals in these areas, including data acquisition frequency, communication bandwidth, and real-time control capabilities; S402, Area Classification: Classify power supply areas according to their similarities. The classification criteria include but are not limited to power supply radius, load type, user density, and new energy penetration rate; S403, Strategy Formulation: Design specific distribution terminal deployment strategies for each type of power supply area. The strategies consider the type, quantity, location of the terminals, and the design of the communication network. For commercial areas with high load density, use higher-performance terminals and stronger communication capabilities. For remote agricultural areas, pay more attention to the reliability of the terminals and low maintenance requirements; S404, Economic Benefit Evaluation: Conduct a cost-benefit analysis of each deployment strategy. The evaluation includes the total cost of terminal procurement cost, installation cost, operation and maintenance cost, and potential savings, i.e., the total cost including reducing fault recovery time and energy waste. Through the Life Cycle Cost (LCC) evaluation model, obtain the long-term economic benefits of each strategy; S405, Strategy Optimization and Adjustment: According to the results of the economic benefit evaluation, optimize and adjust the initially formulated strategies, and conduct repeated iterations to find the deployment plan with the highest cost-benefit ratio; S406, Implementation and Monitoring: Implement the finally determined differential zoning deployment strategy. During the implementation process, establish a monitoring mechanism, regularly collect terminal operation data, and evaluate the actual effect of the strategy to facilitate timely adjustment and optimization.

8. The method for planning the secondary system of an active distribution network according to claim 7, wherein, The S401 economic benefit assessment is used to analyze and optimize the function expansion and deployment strategies of medium and low voltage terminals, identify the solutions that minimize the total cost, and consider economic benefits and return on investment, including the total cost C, total revenue B, and economic benefit E. Then C includes the terminal procurement 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 fault recovery time B f , reducing energy waste B e , the specific costs and revenues are: C = C p + C i + C o , B = B f + B e , introduce the index I of the increase ratio of revenue brought by unit cost. R j is the potential revenue of the j-th area, S j is the power supply importance weight of the j-th area, which can be determined according to factors such as load density and user satisfaction, C j is the deployment cost of the j-th area. Combining with the index I of the increase ratio of revenue, its economic benefit assessment is E innovative = I × E. By calculating, accurately estimate the costs of each function expansion solution, including direct costs such as hardware procurement and software development, and indirect costs such as training and maintenance, and comprehensively evaluate the economic benefits that the expanded terminal can bring, so as to determine the most ideal expansion strategy.

9. The method for planning a secondary system of an active distribution network according to claim 1, wherein 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 such as waveform, frequency, and amplitude, analyzes and processes the traveling wave signals to extract key information required for fault detection, designs a distribution terminal device for real-time acquisition and processing of traveling wave signals, integrates fault detection into the distribution terminal device, and conducts tests in the actual distribution network environment, evaluates the fault detection speed, accuracy, and reliability of the device, and optimizes according to the test results, formulates the deployment strategy of the distribution terminal device, including the quantity, location, and maintenance plan of the device.

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