Fault positioning method for power distribution network containing distributed power supply
By using the forward pushback generation calculation method based on node stratification and technical means such as particle swarm and ant swarm algorithm in the distribution network, a fault segment positioning model including direction coding, dynamic switching function and fault tolerance fitness function is established, and the problem of inaccurate positioning in traditional methods in distributed power distribution networks is solved, and rapid and accurate fault positioning and intelligent development of the distribution network are achieved.
Patent Information
- Application Number
- CN202411773748.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-05
- Publication Date
- 2025-03-14
AI Technical Summary
The traditional distribution network fault positioning method fails to consider the access of distributed power supplies, resulting in inaccurate positioning in the distribution network containing distributed power supplies, and information distortion or uncertainty problems.
The forward pushback generation calculation method based on node hierarchy is used to perform trend calculations, and the impact of distributed power access on fault segment positioning is analyzed, and a fault segment positioning model including direction encoding, dynamic switching function and fault tolerance fitness function is established, and the particle swarm algorithm and ant swarm algorithm are solved.
It improves the accuracy and robustness of fault positioning, adapts to the dynamic characteristics of distributed power supplies, accelerates the fault positioning process, optimizes the operation and maintenance of the distribution network, and promotes the development of intelligent distribution networks.
Smart Images
Figure CN119619724A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of distribution network fault location, and in particular to a distribution network fault location method containing distributed power sources. Background Art
[0002] The access of distributed power sources has brought new challenges to the operation, control, protection and fault handling of traditional distribution networks. In order to ensure the stable operation of the power system, effective measures need to be taken to improve the fault handling capability of the distribution network, especially in a complex distribution network environment containing distributed power sources, which requires more accurate and rapid fault location and recovery strategies.
[0003] Traditional fault location methods for distribution network fault sections fail to take into account the access of distributed power sources, resulting in failure in distribution networks containing distributed power sources. Traditional fault location methods do not consider changes in the direction of fault current and the number of distributed power sources, which may lead to inaccurate positioning. In actual operation, the distribution network may encounter information distortion or uncertainty problems, which will affect the accuracy of fault location.
[0004] To this end, we propose a fault location method for distribution networks containing distributed generation to solve the existing problems. Summary of the invention
[0005] The purpose of the present invention is to address the problems existing in the background technology and to propose a method for locating faults in a distribution network containing distributed power sources.
[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a method for locating faults in a distribution network containing distributed power sources, comprising a power flow calculation module, a fault section location model module and an algorithm solution module, wherein the power flow calculation module adopts a forward-backward calculation method based on node stratification to perform power flow calculation on the distribution network containing distributed power sources, so as to analyze the impact of the access of distributed power sources on the location of the fault section of the distribution network, and then establish the fault section location model to improve the efficiency and accuracy of fault handling, and finally solve the fault section location model through the algorithm solution module to achieve fast and accurate fault section location.
[0007] Preferably, the fault section location model includes direction coding, dynamic switching function and fault-tolerant fitness function. The direction coding can reflect the direction of the fault current. The fault-tolerant mechanism is introduced into the fitness function to solve the information distortion fault, thereby reducing the influence of information distortion on the fault section location and improving the positioning reliability. The dynamic switching function and the fault-tolerant fitness function use a particle swarm algorithm to solve single-point faults and quickly converge to the fault point to achieve precise positioning. The dynamic switching function and the fault-tolerant fitness function use an ant colony algorithm to solve multi-point faults, find the correlation between the fault sections, and achieve accurate positioning of multi-point faults.
[0008] Preferably, the specific steps of the particle swarm algorithm include determining the size of the particle swarm, initializing the particle position, initializing the particle speed, and judging whether the termination condition is met, wherein in each iteration cycle or under specific conditions, the algorithm parameters are adjusted according to the dynamic switch function to adapt to the changes in the solution space or improve the search efficiency, and when abnormal data is detected, the fitness of the particles is re-evaluated using the fault-tolerant fitness function, or the abnormal situation is processed to avoid algorithm crash.
[0009] Preferably, the specific steps of the ant colony algorithm include setting parameters, defining a dynamic switching function, defining a fault-tolerant fitness function, and recording the optimal solution, wherein in each iteration cycle or under specific conditions, the algorithm parameters are adjusted according to the dynamic switching function to adapt to the dynamic changes of the problem, and when abnormal data is detected, the fault-tolerant fitness function is used to re-evaluate the fitness of the path, or handle the abnormal situation.
[0010] Preferably, the fault-tolerant mechanism includes defining a fault-tolerant range, designing a fault-tolerant fitness function, error processing, weight distribution, multiple hypothesis testing, robust optimization and dynamic adjustment, so as to realize adaptive adjustment of the fitness function to adapt to different operating conditions and fault conditions.
[0011] Preferably, the definition of the fault tolerance range includes determining an acceptable degree of information distortion, for example, setting an error range for current and voltage measurement values, and determining a reasonable fault tolerance threshold based on the actual situation of the distribution network and historical data analysis.
[0012] Preferably, the flow calculation module includes data preparation and establishing a mathematical model. The mathematical model includes establishing a node voltage equation for each node in the distribution network, establishing a branch current equation for each branch, considering the access of distributed power sources, and establishing a corresponding injection power equation. The specific calculation steps of the flow calculation module include: initializing injection power, forward process, back substitution process, iterative calculation and verification and adjustment. Through the above detailed steps, the flow of the distribution network containing distributed power sources can be calculated more accurately, providing reliable basic data for subsequent fault section positioning.
[0013] Preferably, the data preparation includes collecting topological data of the distribution network, including parameters of all lines, transformers, distributed power sources (such as photovoltaic, wind power, energy storage systems) and loads, and determining the type, capacity, access location and operating mode (such as grid-connected or off-grid) of the distributed power sources.
[0014] Compared with the prior art, the present invention has the following beneficial effects:
[0015] The method for locating a fault in a distribution network containing a distributed power source of the present invention improves the accuracy of fault location during use: by analyzing the influence of the access of the distributed power source and introducing a mechanism reflecting the direction of the fault current and the number of the distributed power sources, the accuracy of locating the fault section is improved;
[0016] Enhanced model robustness: The fitness function of the fault-tolerant mechanism can handle information distortion and uncertainty, which enhances the robustness of the fault section location model;
[0017] Adapts to the dynamic characteristics of distributed power sources: The method can dynamically reflect the number of connected distributed power sources and adapt to the intermittent and uncertain nature of distributed power sources;
[0018] Accelerate the fault location process: Introduce artificial intelligence algorithms (particle swarm algorithm and ant colony algorithm) to solve the fault section location model, which greatly speeds up the speed of fault location;
[0019] Optimized the operation and maintenance of the distribution network: Fast and accurate fault location helps reduce power outage time, improve the operation efficiency of the distribution network, and reduce maintenance costs;
[0020] Promoted the development of intelligent distribution network: The application of artificial intelligence algorithms has promoted the development of distribution network towards intelligence and automation, and improved the technical level of distribution network;
[0021] Improved system reliability: Accurate fault location helps to eliminate faults in a timely manner, reduce power grid accidents caused by faults, and improve the reliability of the entire distribution network system;
[0022] In summary, it ensures that the distribution network containing distributed power sources can locate the fault section more effectively, ensures the safe and stable operation of the power grid, and at the same time promotes the advancement of distribution network technology and the integration of new energy. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a schematic diagram of the process structure of the present invention; DETAILED DESCRIPTION
[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.
[0025] Embodiment 1
[0026] like Figure 1As shown, the present invention proposes a method for locating faults in a distribution network containing distributed power sources, including a power flow calculation module, a fault section location model module and an algorithm solution module. The power flow calculation module adopts a forward-backward calculation method based on node stratification to perform power flow calculation on the distribution network containing distributed power sources to analyze the impact of the access of distributed power sources on the location of the fault section of the distribution network, and then establishes a fault section location model to improve the efficiency and accuracy of fault processing. Finally, the fault section location model is solved by the algorithm solution module to achieve fast and accurate fault section location.
[0027] Embodiment 2
[0028] like Figure 1 As shown, the present invention proposes a method for locating a fault in a distribution network containing a distributed power source. Compared with the first embodiment, this embodiment further includes:
[0029] The fault section location model includes direction coding, dynamic switching function and fault tolerance fitness function. Direction coding can reflect the direction of fault current. The specific expression of direction coding is:
[0030] Assume we have a system where current can flow in both directions, and we define a reference direction (e.g., from node A to node B is the positive direction). We can use a 2-bit binary code to represent the direction of the current:
[0031] The first bit (high bit) indicates whether the current is flowing in the reference direction.
[0032] The second bit (low bit) indicates whether there is a fault current.
[0033] The encoding rules are as follows:
[0034]
[0035] Here I represents the actual value of the current, a positive number represents that the current flows in the reference direction, and a negative number represents that the current flows in the opposite direction of the reference direction.
[0036] Specific expression:
[0037] “01”: No fault current, the system is normal.
[0038] "10": There is a fault current and the current direction is consistent with the reference direction.
[0039] "11": There is a fault current and the current direction is opposite to the reference direction.
[0040] This coding method is simple and clear, and the direction of current flow can be easily determined by the monitoring system.
[0041] A fault-tolerant mechanism is introduced into the fitness function to solve the information distortion fault, thereby reducing the impact of information distortion on the fault section location and improving the location reliability. The specific expression of the fitness function is:
[0042] Assume we have the following parameters and conditions:
[0043] F i : The reading of the i-th fault indicator (can be current, voltage, impedance, etc.).
[0044] T i : The threshold of the i-th fault indicator.
[0045] N: The total number of fault indicators in the system.
[0046] δ i : The reliability coefficient of the i-th fault indicator, used to indicate the credibility of the indicator.
[0047] L j : The length of the jth fault segment.
[0048] α: Attenuation coefficient between the fault indicator reading and the distance to the fault section.
[0049] D ij : The distance between the i-th fault indicator and the j-th fault section.
[0050] The fitness function F can be designed as:
[0051]
[0052] in:
[0053] M is the total number of failed segments.
[0054] sgn(x) is the sign function, which returns 1 when x>0, 0 when x=0, and -1 when x<0.
[0055] The specific explanation of the fitness function is as follows:
[0056] The part represents the influence of the distance between fault indicator i and fault section j on the location of the fault section. This expression increases with D ij Close to L j An increase means that the fault indicator is more likely to indicate this section.
[0057] The Fault Indicator is active. i >T i , then the fault indicator i is activated, indicating that there may be a fault. Reliability coefficient δ iUsed to adjust the reliability of the fault indicator, δ i The value of is between 0 and 1.
[0058] It means that the readings of all fault indicators are multiplied, so that the fitness of a section is high only when all relevant fault indicators indicate that a section may have a fault.
[0059] It means that the fitness of all faulty sections is summed up to finally obtain the fitness of the entire system.
[0060] The dynamic switch function can dynamically reflect the number of distributed power sources connected to adapt to the fault section location in different scenarios. Its specific expression is:
[0061] Assume we have the following parameters:
[0062] N: The number of distributed power sources currently connected.
[0063] N min : The minimum number of distributed power sources for the system to operate normally.
[0064] N max : The maximum number of distributed power sources that the system can withstand.
[0065] S: The output of the switch function, indicating the operating status or control command of the system.
[0066] The switching function f(N) can be expressed as:
[0067]
[0068] The specific meaning of this function is as follows:
[0069] When the number of connected distributed generation sources N is less than the minimum number N min When the system is not functioning properly, the output is 0, indicating that emergency measures or backup power supply are required.
[0070] When the number of connected distributed generation is N min and N max When the system is in normal working condition, the output is 1.
[0071] When the number of connected distributed generation reaches or exceeds the maximum number N max When the system is at risk of overload, the output is 2, indicating that measures need to be taken to reduce the number of connected power sources or to enhance the system's carrying capacity.
[0072] The fault-tolerant mechanism includes defining the fault-tolerant range and designing the fault-tolerant fitness function. The refinement of the fault-tolerant mechanism includes error processing: for errors in the measurement data, filtering or smoothing techniques (such as Kalman filtering) are used to reduce the impact of noise. For errors in the measurement data, filtering or smoothing techniques (such as Kalman filtering) are used to reduce the impact of noise.
[0073] Weight assignment: For errors in the measured data, filtering or smoothing techniques (such as Kalman filtering) are used to reduce the impact of noise. For errors in the measured data, filtering or smoothing techniques (such as Kalman filtering) are used to reduce the impact of noise.
[0074] Multi-hypothesis testing: Establish multiple hypothetical scenarios, each of which considers different information distortion situations, locate the fault section for each hypothetical scenario, and compare their fitness function values.
[0075] Robust optimization: Robustness indicators are added to the fitness function, such as minimizing the maximum error, to ensure the stability of the positioning results under uncertain conditions, and robust optimization algorithms are used to solve the fault section location problem, such as robust linear programming or robust quadratic programming.
[0076] Dynamic adjustment: According to the real-time operating status of the distribution network and the dynamic changes of the measurement data, the fault-tolerant parameters and the fitness function are adjusted in real time, thereby realizing adaptive adjustment of the fitness function to adapt to different operating conditions and fault conditions. Defining the fault-tolerant range includes determining the acceptable degree of information distortion, for example, setting the error range of the current and voltage measurement values, and determining a reasonable fault-tolerant threshold based on the actual situation of the distribution network and historical data analysis.
[0077] Embodiment 3
[0078] like Figure 1 As shown, the present invention proposes a method for locating a fault in a distribution network containing a distributed power source. Compared with the first embodiment, this embodiment further includes:
[0079] The specific steps of the particle swarm algorithm include determining the size of the particle swarm, initializing the particle position, initializing the particle speed, and judging whether the termination condition is met. In each iteration cycle or under specific conditions, the algorithm parameters are adjusted according to the dynamic switch function to adapt to the changes in the solution space or improve the search efficiency. When abnormal data is detected, the fitness of the particles is re-evaluated using the fault-tolerant fitness function, or the abnormal situation is processed to avoid algorithm crash. The specific steps of the ant colony algorithm include setting parameters, defining dynamic switch functions, defining fault-tolerant fitness functions, and recording the optimal solution. In each iteration cycle or under specific conditions, the algorithm parameters are adjusted according to the dynamic switch function to adapt to the changes in the solution space or improve the search efficiency. When abnormal data is detected, the fitness of the particles is re-evaluated using the fault-tolerant fitness function, or the abnormal situation is processed to avoid algorithm crash. The function adjusts the algorithm parameters to adapt to the dynamic changes of the problem. When abnormal data is detected, the fault-tolerant fitness function is used to re-evaluate the fitness of the path, or to handle the abnormal situation. The fault section location model is solved by the above algorithm. The dynamic switch function and the fault-tolerant fitness function use the particle swarm algorithm to solve single-point faults, and quickly converge to the fault point to achieve accurate positioning. The dynamic switch function and the fault-tolerant fitness function use the ant colony algorithm to solve multi-point faults, find the association between the fault sections, and achieve accurate positioning of multi-point faults. According to different fault types, the algorithm parameters are adjusted to achieve fast and accurate fault section positioning.
[0080] Embodiment 4
[0081] like Figure 1 As shown, the present invention proposes a method for locating a fault in a distribution network containing a distributed power source. Compared with the first embodiment, this embodiment further includes:
[0082] The power flow calculation module includes data preparation and mathematical model building. Data preparation includes collecting topological data of the distribution network, including parameters of all lines, transformers, distributed power sources (such as photovoltaic, wind power, energy storage system) and loads, and determining the type, capacity, access location and operation mode (such as grid-connected or off-grid) of distributed power sources.
[0083] The mathematical model includes establishing a node voltage equation for each node in the distribution network, establishing a branch current equation for each branch, considering the access of distributed power sources, and establishing the corresponding injection power equation.
[0084] The specific calculation steps of the power flow calculation module are as follows: Initialize the initial voltage value of all nodes, usually assumed to be 1.0 pu (per unit value). For distributed power nodes, set the initial injection power according to their operating mode;
[0085] Forward process: Starting from the power node, the voltage of each node and the current of each branch are calculated according to the node voltage equation and the branch current equation, with special attention paid to the impact of power injection of distributed power nodes on voltage and current;
[0086] Back-substitution process: Starting from the load node, the node voltage value is corrected according to the branch current equation and the node voltage equation, taking into account the voltage regulation capability of the distributed generation access point. Multiple iterations may be required to achieve convergence.
[0087] Iterative calculation: Repeat the forward and backward process until the changes in voltage and branch current of all nodes are less than the preset convergence threshold. During the iterative process, the injected power of the distributed generation needs to be continuously adjusted to adapt to the voltage and frequency changes of the power grid;
[0088] Verification and adjustment: Check whether the calculation results satisfy the power balance equation of all nodes. If there is an imbalance, adjust the output of distributed power sources or take other measures. Through the above detailed steps, the power flow of the distribution network containing distributed power sources can be calculated more accurately, providing reliable basic data for the subsequent fault section positioning.
[0089] The above-mentioned specific embodiments are only several preferred embodiments of the present invention. Based on the technical solutions of the present invention and the relevant inspirations of the above-mentioned embodiments, those skilled in the art can make various alternative improvements and combinations to the above-mentioned specific embodiments.
[0090] 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 locating faults in a distribution network containing distributed power sources, comprising a power flow calculation module, a fault section location model module and an algorithm solution module, characterized in that: The power flow calculation module adopts a forward-backward calculation method based on node stratification to perform power flow calculation on the distribution network containing distributed power sources, so as to analyze the impact of the access of distributed power sources on the fault section location of the distribution network, and then establish the fault section location model to improve the efficiency and accuracy of fault handling. Finally, the fault section location model is solved by the algorithm solution module to achieve fast and accurate fault section location.
2. A method for locating faults in a distribution network containing distributed power sources according to claim 1, characterized in that: The fault section location model includes direction coding, dynamic switching function and fault-tolerant fitness function. The direction coding can reflect the direction of the fault current. The fault-tolerant mechanism is introduced into the fitness function to solve the information distortion fault, thereby reducing the influence of information distortion on the fault section location and improving the positioning reliability. The dynamic switching function and the fault-tolerant fitness function use the particle swarm algorithm to solve the single-point fault, quickly converge to the fault point to achieve accurate positioning. The dynamic switching function and the fault-tolerant fitness function use the ant colony algorithm to solve the multi-point fault, find the association between the fault sections, and achieve accurate positioning of the multi-point fault.
3. A method for locating faults in a distribution network containing distributed power sources according to claim 2, characterized in that: The specific steps of the particle swarm algorithm include determining the size of the particle swarm, initializing the particle position, initializing the particle speed, and judging whether the termination condition is met. In each iteration cycle or under specific conditions, the algorithm parameters are adjusted according to the dynamic switch function to adapt to the changes in the solution space or improve the search efficiency. When abnormal data is detected, the fitness of the particles is re-evaluated using the fault-tolerant fitness function, or the abnormal situation is processed to avoid algorithm crash.
4. A method for locating faults in a distribution network containing distributed power sources according to claim 2, characterized in that: The specific steps of the ant colony algorithm include setting parameters, defining a dynamic switch function, defining a fault-tolerant fitness function, and recording the optimal solution. In each iteration cycle or under specific conditions, the algorithm parameters are adjusted according to the dynamic switch function to adapt to the dynamic changes of the problem. When abnormal data is detected, the fault-tolerant fitness function is used to re-evaluate the fitness of the path, or the abnormal situation is handled.
5. A method for locating faults in a distribution network containing distributed power sources according to claim 2, characterized in that: The fault-tolerant mechanism includes defining the fault-tolerant range, designing the fault-tolerant fitness function, error processing, weight distribution, multiple hypothesis testing, robust optimization and dynamic adjustment, and realizes adaptive adjustment of the fitness function to adapt to different operating conditions and fault conditions.
6. A method for locating faults in a distribution network containing distributed power sources according to claim 5, characterized in that: Defining the fault tolerance range includes determining an acceptable degree of information distortion, for example, setting an error range for current and voltage measurements, and determining a reasonable fault tolerance threshold based on the actual situation of the distribution network and historical data analysis.
7. A method for locating faults in a distribution network containing distributed power sources according to claim 1, characterized in that: The flow calculation module includes data preparation and establishment of a mathematical model. The mathematical model includes establishing a node voltage equation for each node in the distribution network, establishing a branch current equation for each branch, considering the access of distributed power sources, and establishing a corresponding injection power equation. The specific calculation steps of the flow calculation module include: initialization of injection power, forward process, back substitution process, iterative calculation and verification and adjustment. Through the above detailed steps, the distribution network flow containing distributed power sources can be calculated more accurately, providing reliable basic data for subsequent fault section positioning.
8. A method for locating faults in a distribution network containing distributed power sources according to claim 7, characterized in that: The data preparation includes collecting topological data of the distribution network, including parameters of all lines, transformers, distributed power sources (such as photovoltaic, wind power, energy storage system) and loads, and determining the type, capacity, access location and operation mode (such as grid-connected or off-grid) of distributed power sources.