Dynamic protection constant value cooperation method for 30-degree phase angle difference non-perception loop closing of power distribution network

Abstract

The invention discloses a power distribution network 30-degree phase angle difference non-perception loop closing dynamic protection constant value cooperation method, and relates to the technical field of power grid automation, and the method comprises the following steps: extracting a protection equipment connection relation based on a power distribution network topology structure, and constructing a topology model containing a hierarchical membership relation; according to the real-time measurement data, generating an interval load distribution model by adopting a periodic entropy weight correction removing algorithm; simulating a load transfer process under a 30-degree phase angle difference based on the topology model and the interval load distribution model, and outputting current change time sequence data of the transfer path protection equipment; according to the hierarchical membership relationship and the current change time sequence data, calculating and checking a protection constant value, and dynamically adjusting the protection constant value by using an impact tolerance coefficient to generate a final protection constant value; and issuing the final protection constant value to the protection equipment, and triggering load transfer operation.

Description

Technical Field

[0001] This invention relates to the field of power grid automation technology, and more specifically, to a dynamic protection setting coordination method for a 30-degree phase angle difference-free loop closure in a distribution network. Background Technology

[0002] In order to improve power supply reliability and flexibility, distribution networks often adopt a dual-power-source "tandem" structure to achieve ring network operation. However, in some areas, due to the different connection groups of transformers in different substations, there is a fixed phase angle difference of 30 degrees on the 10kV side output voltage. Under this structure, if the necessary power flow assessment and protection setting adjustment are not performed during loop closing operation, it is easy to cause serious parallel circulating current, voltage fluctuations, and maloperation or failure of protection devices, directly affecting the operational safety of the distribution network and the continuity of power supply for users.

[0003] For example, the invention patent announcement CN116667296A, entitled "Protection Setting Management Method and System Applicable to Frequent Changes in Network Structure," discloses an automatic protection setting management scheme for changes in distribution network structure. This scheme constructs a protection topology model, updates the changed area using local topology search, identifies protection levels using a breadth-first search algorithm, and sets protection settings for various switches (main lines, branch lines, and users) using a level-based setting reduction rule. Combined with a SCADA system, it achieves automatic setting distribution.

[0004] The above-disclosed technical solutions have at least the following technical problems: While the current solution addresses protection setting management in scenarios with frequent changes in the power grid structure, achieving automatic calculation and remote distribution of settings, its method essentially relies on static topology hierarchy and fixed gradation rules for setting configuration. This fails to handle the actual power flow impact and current surges caused by a 30-degree phase angle difference between power sources. Particularly during loop closing operations, it lacks dynamic simulation and electrical quantity sensing of the load transfer process, cannot identify the actual current changes of each protection device in the switching path, and does not establish a setting transition mechanism for the loop closing point at the moment of load switching. Therefore, it is difficult to guarantee the selectivity and reliability of protection actions. Furthermore, this solution lacks closed-loop control logic linked to the operation sequence and real-time monitoring, failing to support fully automated execution and "zero-awareness" switching on the user side. Therefore, when facing the special, complex, and high-risk application scenario of loop closing in a dual-power system with a 30-degree phase angle difference, the existing solution lacks dynamic response and control coordination capabilities, failing to meet the actual operational requirements of high reliability and high real-time performance.

[0005] To address the above problems, this invention proposes a solution. Summary of the Invention

[0006] To overcome the aforementioned deficiencies of the prior art, embodiments of the present invention provide a dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and no sensing loop closure. This method establishes an interval load allocation model through a de-periodic entropy weight correction algorithm, dynamically calculates protection settings, and adjusts the loop closure point settings in stages. This addresses the problems of insufficient load allocation accuracy, lack of dynamic response and control coordination capabilities, and inability to meet the actual operational requirements of high reliability and high real-time performance in existing schemes.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure includes the following steps: extracting the connection relationships of protection devices based on the distribution network topology and constructing a topology model containing hierarchical membership relationships; generating an interval load distribution model using a de-periodic entropy weight correction algorithm based on real-time measurement data; simulating the load transfer process under a 30-degree phase angle difference based on the topology model and the interval load distribution model, and outputting the current change time series data of the transfer path protection devices; calculating and verifying the protection settings based on the hierarchical membership relationships and the current change time series data, dynamically adjusting the protection settings using the impulse tolerance coefficient, and generating the final protection settings; and issuing the final protection settings to the protection devices to trigger the load transfer operation.

[0008] In a preferred embodiment, the step of extracting the connection relationship of protection equipment based on the distribution network topology and constructing a topology model containing hierarchical membership relationships specifically involves: extracting the switching equipment with protection functions and their connection relationships based on the distribution network topology, and constructing a protection topology model; taking the 10kV bus outlet switch of the substation as the root node, traversing the downstream protection equipment level by level along the protection topology model to generate the hierarchical membership relationships of each protection equipment.

[0009] In a preferred embodiment, the step of generating the interval load allocation model using the de-periodic entropy weight correction algorithm is as follows: Based on the real-time measurement point distribution, the feeder is divided into independent intervals with boundary measurements; the total load of each interval is calculated using the input and output power measurement values ​​at the boundary of each interval; the time-series power consumption data of each load point within the interval is obtained; and the allocation relationship between the total load of the interval and each load point is established using the de-periodic entropy weight correction algorithm to obtain the interval load allocation model.

[0010] In a preferred embodiment, the specific steps for establishing the allocation relationship of the total load of the interval to each load point using the deperiodic entropy weight correction algorithm are as follows: Fourier transform the historical electricity consumption data of each load point within the interval to extract the periodic benchmark electricity consumption pattern; calculate the deviation between the historical electricity consumption data and the benchmark electricity consumption pattern to obtain a deperiodic deviation sequence; calculate the corrected information entropy of each load point based on the deperiodic deviation sequence of each load point, and divide the load points into different electricity consumption behavior pattern categories using an unsupervised clustering algorithm; obtain the entropy-sensitive correction coefficient through a normalization function based on the average entropy value of each cluster category; combine the corrected information entropy and the entropy-sensitive correction coefficient to calculate the allocation weight of each load point, and establish the allocation relationship of the total load of the interval to each load point.

[0011] In a preferred embodiment, the specific steps for acquiring the current change time sequence data are as follows: Based on the protection topology model, identify the tie switch as the closing point and the sectionalizing switch as the unclosing point; through the interval load distribution model, redistribute the load after closing the closing point and opening the unclosing point, and calculate the load current value of each interval after the load transfer; according to the load current value, map it to the protection equipment on the transfer path to generate current change time sequence data.

[0012] In a preferred embodiment, the specific steps for calculating and verifying the protection settings are as follows: based on the hierarchical relationship of the protection devices, calculate the theoretical protection settings of each protection device according to the principle that the protection settings decrease as the level increases; obtain the current protection settings of each protection device, and calculate the verification threshold based on the current protection settings and the preset verification coefficient; compare the current change time series data during the load transfer process with the theoretical protection settings and the verification threshold to generate the verification result.

[0013] In a preferred embodiment, the specific steps for dynamically adjusting the protection setting using the impact tolerance coefficient to generate the final protection setting are as follows: A temporary protection setting before switching is generated by weighting the current operating current value of the loop-breaking switch with the preset impact tolerance coefficient; the temporary protection setting is sent to the loop-breaking switch to perform the switching operation; after the switching is completed, the operating protection setting of the loop-breaking switch is recalculated according to the load distribution and hierarchical relationship, and a replacement temporary setting is sent.

[0014] In a preferred embodiment, the specific steps for issuing the final protection setting to the protection device and triggering the load transfer operation are as follows: the adjusted protection setting is issued to the corresponding protection device through the protection control system; after the setting takes effect, the operation sequence of closing and then opening is executed: first, the tie switch is closed to realize closed-loop operation, and then the unlooping point sectionalizing switch is opened to complete the load transfer.

[0015] In a preferred embodiment, after issuing the final protection setting to the protection device and triggering the load transfer operation, the process further includes dynamically updating the protection topology model and the hierarchical relationship of the protection device. The specific steps are as follows: based on the changes in the state of the distribution network switches, identify and locate the local change area of ​​the topology structure; perform real-time analysis of the feeder connection relationship within the change area and update the protection topology model; and update the hierarchical membership relationship of the protection device on the changed feeder using a graph traversal algorithm.

[0016] The technical effects and advantages of the dynamic protection setting coordination method for a 30-degree phase angle difference in a distribution network without sensing loop closure in this invention are as follows: This invention constructs a protection topology model, establishes an interval load distribution model through a de-periodic entropy weight correction algorithm, and simulates the load transfer process under loop closing scenarios. By combining current change information, it dynamically calculates and verifies protection settings, thereby achieving real-time linkage between protection strategies and operating status. This improves the protection accuracy and system response speed during loop closing operations. By setting temporary and operating settings for the loop breaking point, it helps ensure protection coordination during the transition process, effectively solving the problem that existing solutions lack dynamic response and control coordination capabilities, and cannot meet the actual operating requirements of high reliability and high real-time performance. Attached Figure Description

[0017] Figure 1 A schematic diagram of the dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and no sensing loop closure provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the interval load allocation provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the loop closure and unclosure operation provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the protection setting verification process provided in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1, Figure 1 The present invention provides a dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure, comprising the following steps: S1. Based on the distribution network topology, extract the connection relationship of protection devices and construct a topology model containing hierarchical membership relationships; S2, Based on real-time measurement data, an interval load allocation model is generated using a de-periodic entropy weight correction algorithm; S3, based on the topology model and the interval load distribution model, simulates the load transfer process under a 30-degree phase angle difference and outputs the current change timing data of the transfer path protection equipment. S4. Based on the hierarchical affiliation and current change time series data, calculate and verify the protection setting value, dynamically adjust the protection setting value using the impact tolerance coefficient, and generate the final protection setting value. S5 sends the final protection setting to the protection device, triggering the load transfer operation.

[0020] This embodiment effectively compresses the scale of the distribution network model by constructing a protection topology model, simplifying the complex topology containing a large number of devices into a streamlined model that only retains protection switches, significantly improving computational efficiency. Through the interval load allocation model, it achieves accurate load current allocation based on real-time measurements, providing an accurate electrical parameter basis for switching operations. Real-time verification and dynamic setting adjustment mechanisms ensure the reasonable configuration of the settings of each protection device during the 30-degree phase angle difference loop closing operation, effectively avoiding the risk of protection malfunctions caused by load transfer. Through the standardized operation sequence of closing before opening and real-time monitoring technology, it achieves automated execution and safe and reliable control of switching operations. Ultimately, it successfully realizes the leap from the traditional "short-term power outage" mode to a "zero-perception" continuous power supply mode for distribution network load transfer, significantly improving power supply reliability and user experience, and providing important technical support for the intelligent operation of the distribution network.

[0021] S1. Based on the distribution network topology, extract the connection relationship of protection devices and construct a topology model containing hierarchical membership relationships.

[0022] In this embodiment, the step of extracting the connection relationships of protection devices based on the distribution network topology and constructing a topology model containing hierarchical membership relationships specifically involves: Based on the distribution network topology, we extract the switching equipment with protection functions and their connection relationships to construct a protection topology model. Using the 10kV busbar outlet switch of the substation as the root node, the downstream protection equipment is traversed level by level along the protection topology model to generate the hierarchical relationship of each protection equipment.

[0023] Specifically: A complete topology model of a 10kV distribution network includes a large number of devices and their connections. Since protection devices are closely related to switchgear, from the perspective of protection setting management, a detailed topology model is not required. It is sufficient to establish a simplified model that reflects the upstream and downstream hierarchical relationships of each switch on the feeder.

[0024] First, switchgear equipped with protection devices is selected from the detailed topology model of the distribution network, including 10kV outgoing switches of substations, sectionalizing switches, tie switches, and incoming switches of users. Equipment that does not directly participate in protection coordination, such as isolating switches, distribution transformers, and capacitors, is eliminated, retaining only the electrical connections between these protection switches, resulting in a significantly reduced protection topology model.

[0025] Furthermore, based on the constructed protection topology model, a breadth-first search algorithm is used for hierarchical analysis. Taking the 10kV busbar outlet switch of the substation as the root node, with a level value set to 0, a breadth-first search begins from this root node. For each node at the current level, all its adjacent downstream nodes are traversed, and the level value of these downstream nodes is set to the current level value plus 1. This process is repeated layer by layer downwards until all nodes in the entire protection topology model have been traversed.

[0026] By employing a breadth-first search algorithm, the distance hierarchy of each protection device relative to the power source (10kV busbar of the substation) is obtained. A smaller hierarchy value indicates that the protection device is closer to the power source and is positioned upstream in protection coordination; a larger hierarchy value indicates that the device is farther from the power source and is positioned downstream. This hierarchical relationship directly reflects the upstream and downstream coordination between the protection devices, providing an important basis for subsequent protection setting calculations and coordination.

[0027] For example, a 10kV feeder starts from the substation outlet switch and connects to sectionalizing switch A, sectionalizing switch B, and tie switch C in sequence. After breadth-first search, the outlet switch is at level 0, sectionalizing switch A is at level 1, sectionalizing switch B is at level 2, and tie switch C is at level 3. Based on the principle that protection settings decrease with increasing distance from the power source, the protection settings for each switch should satisfy: outlet switch setting > sectionalizing switch A setting > sectionalizing switch B setting > tie switch C setting, thus ensuring selective coordination of protection.

[0028] S2, based on real-time measurement data, uses a de-periodic entropy weight correction algorithm to generate an interval load distribution model.

[0029] In this embodiment, the specific steps for generating the interval load allocation model using the de-periodic entropy weight correction algorithm are as follows: Based on the real-time measurement point distribution, the feeder is divided into independent intervals with boundary measurements; The total load of each interval is calculated by measuring the input and output power at the boundaries of each interval. The time-series electricity consumption data of each load point within the interval are obtained, and the distribution relationship of the total load of the interval to each load point is established by the de-periodic entropy weight correction algorithm, thus obtaining the interval load distribution model.

[0030] The specific steps for establishing the distribution relationship of the total load of the interval to each load point using the deperiodic entropy weight correction algorithm are as follows: Fourier transform is performed on the historical electricity consumption data of each load point within the interval to extract the periodic reference electricity consumption pattern. The deviation between the historical electricity consumption data and the reference electricity consumption pattern is calculated to obtain the deperiodic deviation sequence. The corrected information entropy of each load point is calculated based on the deperiodic deviation sequence of each load point, and the load points are divided into different electricity consumption behavior pattern categories by an unsupervised clustering algorithm. Based on the average entropy value of each cluster category, the entropy-sensitive correction coefficient is obtained through a normalization function; By combining the corrected information entropy and the entropy sensitivity correction coefficient, the allocation weight of each load point is calculated, and the allocation relationship of the total load of the interval to each load point is established.

[0031] Specifically: In power distribution networks, real-time measurement points are typically located at critical nodes, such as substation outlets, important branch points, and large customer inbound points. These measurement points provide real-time electrical data such as voltage, current, and power. Based on the distribution of these real-time measurement points, the entire feeder is divided into several independent sections, ensuring that each section has a real-time measurement point at its boundary, while there are no real-time measurement points inside the section.

[0032] by Figure 2 Taking the feeder shown as an example, assuming that in , , If a real-time measurement point is located at the position, the feeder can be divided into two independent sections: the first section Depend on , , The second interval is formed by three measurement points. for The subsequent terminal region, The locations are other measurement points used for calculations in other areas. This division method ensures that each section is electrically independent, and that the measurement data at the section boundaries accurately reflects the input and output power of the section.

[0033] For each defined interval, the net power consumption of that interval is calculated based on the power data from the measurement points at the boundaries. Taking the first interval as an example, this interval has three boundary measurement points. , , The total load of that section Equal to the data measured at the three boundary measurement points , , The sum, that is:

[0034] For the terminal interval, since there is only one input measurement point... There is no output, therefore the total load of this interval is directly equal to... The measured value.

[0035] After determining the total load of each interval, this total load needs to be rationally allocated to the various load points within the interval. Traditional methods typically rely on simple proportional allocation based on pseudo-measurement data from load forecasting, but this method is highly subjective and has limited accuracy. This embodiment introduces information entropy theory and employs a de-periodic entropy weight correction algorithm to determine the allocation weight of each load point, achieving a more objective and accurate load allocation. The specific steps are as follows: First, periodic patterns are extracted. Fourier transform analysis is performed on the historical electricity consumption data of each load point over the past 30 days to extract the fundamental frequency components of the 24-hour daily cycle and the 7-day weekly cycle, thus constructing the periodic benchmark electricity consumption patterns for each load point. Here, i represents the load point number, and t represents time. For example, residential load typically exhibits a daily cycle with peak electricity consumption in the morning and evening, while industrial load exhibits a weekly cycle with high consumption on weekdays and low consumption on weekends. Fourier analysis can accurately identify and quantify these periodic patterns.

[0036] Next, de-periodicization is performed. The actual electricity consumption data for each load point is calculated. The deperiodic sequence is obtained by comparing the deviation from its periodic reference pattern: The deperiodic bias sequence eliminates predictable periodic changes while retaining true random fluctuations, making subsequent entropy weight calculations more accurate.

[0037] Then, the corrected information entropy is calculated. The corrected information entropy for each load point is calculated based on the deperiodic deviation sequence of each load point. :

[0038] in This is the probability density function for the deperiodic deviation value. The corrected information entropy accurately reflects the true uncertainty of electricity consumption behavior at a load point; the smaller the entropy value, the smaller the electricity consumption deviation at that load point, and the more stable and reliable it is.

[0039] To further improve allocation accuracy, the algorithm needs to be adaptively adjusted based on load type. Different types of loads exhibit significant differences in electricity consumption behavior. Therefore, this embodiment uses unsupervised clustering to automatically identify load types from electricity consumption patterns and quantify their impact on weight adjustments. Specifically, based on historical electricity consumption data, the DBSCAN clustering algorithm is used to divide load points into several categories, each representing a typical electricity consumption behavior pattern.

[0040] After clustering, the entropy sensitivity coefficient λ(cluster) for each load cluster is obtained by combining the statistical distribution of entropy values ​​of the load points in that cluster. This coefficient is then used to adjust the final weight allocation. Specifically, for each cluster, the set of corrected entropy values ​​for all load points in that cluster is extracted, and the average entropy value for that cluster is calculated. The entropy sensitivity coefficient is generated using the following normalization function:

[0041] in , These are the maximum and minimum average entropy values ​​among all cluster categories, respectively. , The adjustment interval is set to [0.8, 1.2] to define the boundary of the coefficient adjustment interval. This mechanism ensures that categories with smaller average entropy values ​​(i.e., more stable and predictable loads) receive larger correction coefficients, reflecting their high reliability in load allocation.

[0042] The final weight calculation formula is:

[0043] in This is the entropy-sensitive correction coefficient for the cluster category to which load point i belongs. This is the corrected information entropy value for load point i.

[0044] For example, given three load points A, B, and C within a certain interval, cluster analysis is used to divide them into three groups, and the corresponding entropy sensitivity correction coefficients are obtained as λ(A) = 1.1, λ(B) = 0.9, and λ(C) = 0.7, respectively. After deperiodicization, the corrected information entropy of each load point is calculated as follows: =0.3、 =0.5 and =0.7. Using the weighting formula, the assigned weights for load points A, B, and C are calculated as follows: =0.71、 =0.29 and =0, then the actual power allocated to load point A is: ,in This represents the total load of the interval.

[0045] Using the above method, the distribution relationship of the total load of the interval to each load point is established, forming an interval load allocation model. Compared with the traditional simple proportional allocation method based on pseudo-measurement data of load forecast, this embodiment introduces information entropy theory for load allocation. However, directly applying the traditional entropy weight method has two key obstacles: first, the distribution network load data has obvious time periodicity, which will interfere with the accuracy of entropy value calculation; second, the variation characteristics of different types of loads are very different, requiring differentiated processing. To address these obstacles, the designed de-periodic entropy weight correction algorithm effectively solves these problems and achieves more objective and accurate load allocation. This model can allocate the total load of the interval obtained from boundary measurements to each load point within the interval in a reasonable proportion, providing an accurate load data basis for subsequent simulation of current distribution after load transfer. When the operation mode of the distribution network changes, such as during load transfer, the new load distribution of each load point can be quickly calculated based on this model.

[0046] S3, based on the topology model and the interval load distribution model, simulates the load transfer process under a 30-degree phase angle difference and outputs the current change timing data of the transfer path protection device.

[0047] In this embodiment, the specific steps for acquiring the current change timing data are as follows: Based on the protection topology model, the tie switch is identified as the closing point and the sectionalizing switch is identified as the unclosing point. Using the aforementioned interval load distribution model, the load is redistributed after the closing of the loop point and the opening of the loop point, and the load current value of each interval is calculated after the load transfer. Based on the load current value, it is mapped to the protection device on the transfer path to generate current change timing data.

[0048] Specifically: Based on the established protection topology model, the daisy-chain network structure with load transfer conditions in the distribution network is identified. In a daisy-chain network, there is typically a disconnected tie switch, such as... Figure 3 As shown in Figure S, the tie switch connects two different feeders X and Y, forming a potential ring network structure. This tie switch is designated as the closing point, i.e., the starting point for load transfer. Simultaneously, a sectionalizing switch is selected on the source feeder from which the load is about to be transferred as the unclosing point. This sectionalizing switch will open after the load transfer is completed to release the ring network from operation.

[0049] After determining the loop closing and loop closing points, the load transfer process is simulated using a section load distribution model. Assume that feeder X and feeder Y are connected to the two sides of the tie switch, and the load currently carried by feeder X needs to be transferred to feeder Y. First, the load distribution of the two feeders before the transfer is calculated: based on the load distribution model for each section, the current load of each section of feeder X is obtained. , ... and the current load of each section of feeder Y. , .

[0050] When the tie switch is closed, a ring network operation is formed. At this point, the 30-degree phase angle difference constraint needs to be considered. Phase angle measurements confirm that the phase angle difference across the tie switch is within 30 degrees, satisfying the ring-closing condition. A circulating current will be generated at the moment of ring closure; the magnitude of the circulating current is related to factors such as the phase angle difference and system impedance. Under the 30-degree phase angle difference condition, the ring-closing inrush current is relatively small and will not cause serious impact on the system.

[0051] Next, the load redistribution process after the loop-breaking point is activated is simulated. When the sectionalizing switch (loop-breaking point) on feeder X is opened, for example... Figure 3 In The load originally powered by feeder X will be transferred to feeder Y via the tie switch. At this time, feeder Y will need to handle the original load. , ... And the load transferred from feeder X , ... , where k is the number of intervals upstream of the loop point. The load current distribution of each interval after the transfer is recalculated using the interval load distribution model.

[0052] Based on the new load distribution after load transfer, calculate the change in current carried by each protection device along the transfer path. The transfer path refers to all protection devices from the output switch of feeder Y, through the tie switch, to the loop-breaking point. For each protection device along the path, calculate the increment of its current carried based on the change in its downstream load. For example, the current carried by a certain protection device originally... After the transfer, it needs to additionally bear the current generated by the transferred load. Then the total current after the protection device is transferred is .

[0053] The above calculations yielded the time-series data of current changes for each protection device along the load transfer path, including current comparisons before and after load transfer, current increments, and the closing-loop inrush current considering the 30-degree phase angle difference. This current change data provides an accurate electrical parameter basis for the subsequent recalculation and verification of protection settings.

[0054] S4. Based on the hierarchical affiliation and current change time series data, calculate and verify the protection setting value, dynamically adjust the protection setting value using the impact tolerance coefficient, and generate the final protection setting value.

[0055] In this embodiment, the specific steps for calculating and verifying the protection settings are as follows: Based on the hierarchical relationship of protection equipment, the theoretical protection settings of each protection equipment are calculated according to the principle that the protection settings decrease as the level increases; Obtain the current protection settings of each protection device, and calculate the verification threshold based on the current protection settings and preset verification coefficients; The current change time series data during the load transfer process is compared with the theoretical protection setting and the verification threshold to generate the verification result.

[0056] Specifically: The specific process of S4 is as follows: Figure 4 As shown, based on the hierarchical relationship of each protection device obtained in S1, and following the matching principle that the protection setting decreases as the distance from the power source increases, the theoretical protection setting of each protection device on the switching path is calculated. The coordination of protection settings follows the upstream and downstream differential matching principle. The setting of the upstream protection should be greater than that of the downstream protection to ensure that the downstream protection takes priority in the event of a fault, thus achieving protection selectivity.

[0057] The basic overcurrent protection setting of the 10kV outlet switch (level 0) of the substation is set to... The setting is determined based on the system short-circuit current and load characteristics. For protection equipment at level n, the theoretical protection setting calculation formula is:

[0058] Where K is the hierarchy reduction factor, which is usually taken as 0.8-0.9 depending on the specific conditions of the distribution network. The selection of the hierarchy reduction factor needs to take into account factors such as line impedance characteristics, load distribution, and short-circuit current attenuation to ensure that the setpoints between adjacent levels have sufficient differences.

[0059] For example, if the basic setting of a 10kV feeder outlet switch is set to 1200A, and a tiered reduction coefficient K=0.85 is selected, then the theoretical protection settings for each level of protection equipment are: Level 1 sectionalizing switch setting: 1200A × 0.85 1 =1020A; the setting of the 2-level sectionalizing switch is 1200A × 0.85 2 =867A; the 3-level tie switch setting is 1200A × 0.85 3 =737A.

[0060] Furthermore, real-time verification is performed before load transfer. The operating current data of each protection device after the transfer, calculated in S3, is compared and analyzed with its currently set protection settings. A verification coefficient α=0.8 is set. The selection of this coefficient takes into account the operating characteristics and operating margin of the protection devices to ensure that the protection will not malfunction under normal load fluctuations.

[0061] For each protection device on the reversal path, the following verification criterion is applied: if the operating current of the protection device after the reversal... satisfy: If so, the protective device is deemed to have a risk of malfunction. The current protection settings for this protection device. The verification threshold means that when the operating current exceeds 80% of the set value, the protection device may be at risk of malfunction, taking into account factors such as current measurement error and load fluctuation.

[0062] The specific verification process is as follows: First, obtain the current protection settings of all protection devices on the transfer path. These settings may be calculated based on historical operating conditions and may not be suitable for the new operating state after the transfer. Then, compare the current after the transfer of each protection device with the verification criteria. Taking the 2-level sectionalizing switch in the previous example as an example, its theoretical protection setting is 867A. Assuming the current protection setting is 800A, the verification coefficient α = 0.8 is set. According to step S3, the operating current of the switch after the transfer is 700A. Therefore, the verification threshold is: 0.8 × 800A = 640A. Since 700A > 640A, the switch has a risk of maloperation and the setting needs to be adjusted or the transfer path replanned.

[0063] Simultaneously, a comparison with the theoretical setpoint is performed: if the current setpoint of 800A is lower than the theoretical value of 867A, it indicates that the protection setpoint of the device is too low, which may affect the protection coordination between upstream and downstream devices. The system outputs a message indicating "Setpoint too low, risk exists" indicating malfunction and mismatch. If the current setpoint is greater than the theoretical protection setpoint, it means that the current protection setpoint of the protection device is too high, and the system prompts "Setpoint too high, review recommended" to remind the operator to adjust the current setpoint.

[0064] For protection devices that fail verification, the system automatically generates risk warning information, including detailed information such as the specific location of the risky device, current settings, expected operating current, and the extent of the exceedance. Operators can choose response strategies based on the risk warning, such as adjusting protection settings, changing transfer paths, or transferring loads in batches.

[0065] In addition to the standard overcurrent protection verification, other protection functions such as zero-sequence protection and instantaneous overcurrent protection also need to be verified. Zero-sequence protection settings are typically set relatively low, primarily for detecting ground faults, and are relatively less affected by load transfer. Instantaneous overcurrent protection settings are set relatively high, used to quickly clear high-current faults near the load; it is necessary to ensure that its setting is greater than the maximum operating current after load transfer.

[0066] The above verification and analysis ensures that the settings of each protection device are reasonable before the switching operation, avoiding protection malfunctions caused by load transfer and laying the foundation for subsequent safe switching operations. The verification results will serve as an important basis for adjusting protection settings, achieving dynamic optimization of protection settings.

[0067] In this embodiment, the specific steps for dynamically adjusting the protection settings using the impact tolerance coefficient to generate the final protection settings are as follows: The temporary protection setting before the switchover is generated by weighting the current operating current value of the loop-breaking point switch with the preset impact tolerance coefficient. The temporary protection setting is sent to the loop-breaking point switch to perform the reversal operation; After the reversal is completed, the operating protection settings of the loop break point switch are recalculated according to the load distribution and hierarchical relationship, and the replacement temporary settings are issued.

[0068] Specifically: After the protection settings have been verified, they need to be dynamically adjusted to adapt to the special operating conditions during load transfer. The protection setting adjustment is divided into two stages: temporary setting adjustment during the switching operation and normal operation setting reset after the switching is completed. Among them, the setting adjustment of the loop-breaking point switch is the key link in the whole process.

[0069] First, the temporary protection settings of the loop-breaking point switch before its switching operation are calculated. The loop-breaking point switch plays a special role in the switching operation; it needs to remain closed during the loop-closing period to bear the transferred load, and then open at an appropriate time to complete the loop-breaking. During the loop-closing phase, the switch needs to withstand the superposition of the loop-closing inrush current and the transferred load current; therefore, its protection settings need to be specially set to avoid malfunctions.

[0070] The formula for calculating the temporary protection setting of the loop-breaking switch is:

[0071] in This is the normal operating current before the switch reverses. To preset the impact tolerance coefficient, a value of 1.5 is typically chosen based on practical engineering experience and safety margin requirements. The selection of this coefficient needs to comprehensively consider factors such as the amplitude of the closing-loop impact current, the load transfer increment, and measurement errors to ensure that the switch will not malfunction due to instantaneous current impact during the switching process.

[0072] For example, if the normal operating current of a certain loop-breaking switch is 400A before it switches over, and the impulse tolerance factor is taken as 1.5, then its temporary protection setting is: =1.5 × 400A = 600A. This temporary setting can withstand the current surge during the loop closing process while maintaining a rapid response capability to severe faults.

[0073] To ensure the rationality of the temporary setpoint, a redundancy coefficient check is also required. The redundancy coefficient β is set to 1.3, and the check condition is as follows:

[0074] in This is the minimum short-circuit current at that location. This verification step ensures that the temporary setting can reliably detect and isolate various faults while providing operational protection. Taking the above example, if the minimum short-circuit current at this location is 1000A, then the verification condition is: 600A × 1.3 = 780A < 1000A, the verification passes, and the temporary setting is reasonable.

[0075] After determining the temporary protection settings, the settings are sent to the loopback switch via the protection control system. The setting sending process employs an encrypted communication protocol to ensure the security and integrity of data transmission. The system automatically verifies the success of the setting sending, including communication status confirmation, setting write confirmation, and setting effectiveness confirmation. Subsequent reversal operations can only be performed after the temporary settings have been successfully sent and taken effect.

[0076] After the temporary setting takes effect, the standard switching operation sequence is executed: first, the tie switch is closed to form a loop network, and then the loop point switch is deactivated to complete the load transfer. Throughout the switching process, the loop point switch operates safely under the temporary setting protection, avoiding malfunctions caused by current surges and ensuring the smooth completion of the switching operation.

[0077] After the switching operation is completed, the operating protection settings of the loop-breaking point switch need to be recalculated. At this time, the topology of the distribution network has changed, the load distribution has been readjusted, and the operating state of the loop-breaking point switch has changed from closed to open. Its protection settings need to be adjusted accordingly to adapt to the new operating mode.

[0078] Based on the new load distribution after the transition is completed, the location and function of the loop-breaking switch in the network are re-analyzed. Since the loop-breaking switch is now open, its main function changes to a backup tie-line, and its protection settings should be recalculated based on potential backflow loads and short-circuit current levels. Normal operating settings The calculation follows the conventional fixed-value tuning principle, namely:

[0079] in This is the maximum load current that the switch can carry. The reliability coefficient is typically set to 1.2-1.3.

[0080] For example, after the switching is completed, the loop breaker switch acts as a backup switch. Its maximum possible load current is 300A, and its reliability factor is taken as 1.2. Therefore, the normal operating setting is: =1.2×300A=360A.

[0081] Finally, the recalculated normal operating settings are sent to the loop-breaking point switch, replacing the previous temporary settings. The settings replacement process also requires a rigorous verification procedure to ensure the new settings are correctly sent and take effect. The system records a detailed log of the entire settings adjustment process, including adjustment time, comparison of settings before and after adjustment, and personnel involved, providing a basis for subsequent operational analysis and fault tracing.

[0082] Through the aforementioned phased dynamic adjustment strategy for protection settings, precise control and adaptive adjustment of protection settings during the switching operation are achieved. This ensures both the safe execution of the switching operation and the normal and stable operation of the system after the switching, providing an important guarantee for the successful implementation of the 30-degree phase angle difference seamless loop closing technology in the distribution network.

[0083] S5 sends the final protection setting to the protection device, triggering the load transfer operation.

[0084] In this embodiment, the specific steps for sending the final protection setting to the protection device and triggering the load transfer operation are as follows: The adjusted protection settings are sent to the corresponding protection devices through the protection control system. After the set value takes effect, the operation sequence of closing and then opening is executed: first close the tie switch to achieve closed-loop operation, and then open the unclosing point sectionalizing switch to complete the load transfer.

[0085] Specifically: The protection control system distributes the adjusted protection settings from S5 to the corresponding protection devices. The protection control system adopts the IEC 61850 communication standard and supports multiple communication methods, including fiber optic, wireless, and carrier wave communication, ensuring reliable communication with various protection devices. The setting distribution process follows a four-step procedure: "verification – distribution – confirmation – effectiveness".

[0086] During the verification phase, the system performs a final check on the protection settings to be issued, including setting rationality verification (checking whether the settings are within the equipment's rated range), logical consistency verification (checking the coordination relationship between upstream and downstream settings), and permission verification (confirming that the operator has the appropriate permissions). After successful verification, the system generates a setting issuance command, which includes information such as the target device address, setting type, setting value, and checksum.

[0087] The setting distribution adopts a point-to-point confirmation mechanism. Each protection device needs to return confirmation information after receiving the setting, including reception status, setting write status, and setting verification result. The system monitors the setting distribution progress in real time and automatically retryes for devices that fail to distribute the setting. If the number of retries exceeds a preset threshold, an alarm is triggered to the operator. For example, if a switching path involves 5 protection devices that need to adjust their setting, the system sequentially distributes the adjusted setting to the output switch, sectionalizing switch A, sectionalizing switch B, tie switch, and unlooping switch. The system continues to distribute the setting to the next device only after each device confirms receipt.

[0088] After the setting is issued and confirmed, the standard "close first, then open" reverse operation sequence is executed. The first step is to close the tie switch. Before closing, the system automatically checks the closing conditions, including phase angle difference measurement, voltage level matching confirmation, and protection setting issuance status confirmation.

[0089] The closing operation is performed remotely, with the operation command sent to the tie switch control unit via an encrypted channel. Upon receiving the closing command, the tie switch first performs a local safety check, including the switch's mechanical condition, the integrity of the operating circuit, and real-time measurement of the phase angle difference. Once all conditions are confirmed to be met, the switch executes the closing action.

[0090] After the tie switch is successfully closed, the system enters a brief ring network operation state. At this time, the two feeders are connected through the tie switch to form a ring network topology, and the load begins to be redistributed. The system monitors the ring network operation status in real time, including parameters such as changes in current of each switch, voltage quality, and power flow distribution, to ensure stable ring network operation.

[0091] After the ring network has been running stably for approximately 3-5 seconds, the second step is executed: the loop breaker switch is opened. The opening operation is also performed remotely, with the opening command sent to the target sectionalizing switch. Upon receiving the opening command, the switch confirms that the current operating current is within a safe range, typically requiring the opening current to be less than 80% of the switch's rated breaking current, and then executes the opening action. After the opening is completed, the original ring network structure is released, and the load transfer operation is finished.

[0092] It should be noted that the entire switching operation process is monitored in real time, with the system continuously collecting and analyzing key electrical parameters. Monitoring includes: confirmation of switch open / closed status, current changes during load transfer, voltage fluctuations during loop closing, whether protection devices have activated, and the communication connection status of each device.

[0093] Monitoring data is stored in a real-time database and displayed on the monitoring interface in real time. A yellow warning is issued when the monitored parameter exceeds the warning threshold; a red alarm is issued when the parameter exceeds the danger threshold or an abnormal state occurs, and emergency operations can be automatically executed. For example, if excessive circulating current is found after loop closure, the system can automatically disconnect the interconnecting switch and restore the original operating mode.

[0094] After the reversal operation is completed, the system generates a detailed operation report, including operation time nodes, response time of each device, electrical parameter change curves, and abnormal event records, providing complete data support for subsequent operation analysis and experience summarization.

[0095] Furthermore, the step of issuing the final protection settings to the protection equipment and triggering the load transfer operation also includes dynamically updating the protection topology model and the hierarchical relationship of the protection equipment. The specific steps are as follows: Based on changes in the state of distribution network switches, identify and locate localized areas of topological change. The feeder connection relationship within the changing area is analyzed in real time, and the protection topology model is updated accordingly. The hierarchical relationship of protection devices on the changing feeder is updated using a graph traversal algorithm.

[0096] Specifically: After the reversal operation is completed, the distribution network topology changes, requiring timely updates to the protection topology model and the hierarchical relationships of each protection device to ensure the accuracy and timeliness of subsequent protection setting management. Traditional whole-network topology reanalysis methods are inefficient, especially in large-scale distribution networks; therefore, local topology search technology is used for targeted updates.

[0097] The core idea of ​​local topology search technology is to reanalyze only the areas where the operating mode has changed, while keeping the topology model of the unchanged areas unchanged. First, the system automatically identifies the switching equipment whose state has changed, mainly including tie switches and unlooping switches involved in switching operations; the former changes from open to closed, and the latter changes from closed to open. Starting from these state-changed switches, a breadth-first search algorithm is used to expand upstream and downstream to determine the affected topology area.

[0098] The search scope is determined according to the "minimum influence area" principle, meaning it only includes areas where the power supply path has actually changed. The specific search process is as follows: Using the switch whose status has changed as the central node, the search proceeds upstream until the first unaffected branch point or substation outlet is encountered, and downstream until the first unaffected end load point or other branch point is encountered. This defined search area includes all protection devices affected by the switching operation, while avoiding unnecessary full-network analysis.

[0099] For example, during a switching operation, the contact switch Close the feeder and sectionalizing switch The circuit breaker tripping completes the loop break. Local search from... and Initially, the search was conducted upstream. and The exit switch searches downstream to find their respective end users, and the final determined influence domain includes... The switches on the top {outlet switch 01, sectionalizing switch} and , contact switch The switches on F2 are: {Outlet switch 02, Section switch} and }

[0100] After determining the influence domain, the protection topology within that region is remodeled. Connections of already tripped switches in the original model are deleted, new connections of closing switches are added, and the adjacency relationships between each switch node are updated. Simultaneously, it is checked whether any new power supply paths have been formed or existing paths have been interrupted, and the power supply source information for the protection equipment is updated accordingly.

[0101] After the protection topology model is updated, a breadth-first search algorithm is used to recalculate the hierarchical relationship of each protection device within the influence domain. The traversal still starts with the 10kV busbar outlet switch of the substation as the root node, but only the nodes within the influence domain are recalculated hierarchically, while the hierarchical relationship of unaffected areas remains unchanged.

[0102] When recalculating the hierarchical relationship, it is important to note that protection devices that were originally at the same level may be at different levels due to the reversal operation, and protection devices that were originally at different levels may be at the same level due to changes in the power supply path. The algorithm traverses downwards layer by layer, checking all adjacent downstream nodes for each node and setting the level of the downstream node to the current node's level plus 1.

[0103] Taking the aforementioned example, the hierarchical relationship on the F1 feeder before the switchover is: Output switch 01 (hierarchy 0) -> (Level 1) -> (Level 2) -> (Level 3, disconnected); The hierarchy on the feeder is: Output switch 02 (level 0) -> (Level 1) -> (Level 2). After the reversal, due to closing the circuit breaker, After the circuit breaker is deactivated, the new hierarchical relationship becomes: via... The connected load is Power supply hierarchy is as follows: Output switch 01 (Level 0) -> (Level 1) -> (Level 2) -> (Level 3) -> (Level 4); It becomes an isolated switch and is temporarily not involved in power supply.

[0104] After the hierarchical relationship is updated, the system automatically checks the rationality of the new hierarchical relationship, including the continuity of hierarchical increments, the independence of devices at the same level, and the consistency between the level and the actual power supply distance. For any anomalies found during the check, the system generates alarm messages to remind maintenance personnel to conduct manual confirmation.

[0105] Finally, the updated protection topology model and hierarchical relationship information are stored in the system database, and update notifications are pushed to relevant application modules. This information will serve as the foundational data for subsequent functions such as protection setting calculations, fault analysis, and operation mode planning, ensuring that the entire protection management system always operates based on the latest and most accurate network topology information.

[0106] Through the aforementioned dynamic update mechanism, the system can maintain the accuracy of the distribution network topology in real time, providing reliable basic data support for continuous protection setting management and subsequent switching operations, thus realizing the adaptive operation and intelligent management of the distribution network protection system.

[0107] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0108] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0109] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0110] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0111] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0112] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure, characterized in that, Includes the following steps: Based on the distribution network topology, the connection relationship of protection equipment is extracted, and a topology model containing hierarchical membership is constructed. Based on real-time measurement data, an interval load allocation model is generated using a de-periodic entropy weight correction algorithm. Based on the topology model and the interval load distribution model, the load transfer process under a 30-degree phase angle difference is simulated, and the current change time series data of the transfer path protection device is output. Based on hierarchical affiliation and current change time series data, the protection settings are calculated and verified, and the protection settings are dynamically adjusted using the impulse tolerance coefficient to generate the final protection settings. The final protection setting is sent to the protection equipment, triggering the load transfer operation.

2. The dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure as described in claim 1, characterized in that, The specific steps for extracting the connection relationships of protection devices based on the distribution network topology and constructing a topology model containing hierarchical membership relationships are as follows: Based on the distribution network topology, we extract the switching equipment with protection functions and their connection relationships to construct a protection topology model. Using the 10kV busbar outlet switch of the substation as the root node, the downstream protection equipment is traversed level by level along the protection topology model to generate the hierarchical relationship of each protection equipment.

3. The dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure as described in claim 2, is characterized in that... The specific steps for generating the interval load allocation model using the deperiodic entropy weight correction algorithm are as follows: Based on the real-time measurement point distribution, the feeder is divided into independent intervals with boundary measurements; Calculate the total load of each interval by measuring the input and output power at the boundaries of each interval; The time-series electricity consumption data of each load point within the interval are obtained, and the distribution relationship of the total load of the interval to each load point is established by the de-periodic entropy weight correction algorithm, thus obtaining the interval load distribution model.

4. The dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure as described in claim 3, is characterized in that, The specific steps for establishing the distribution relationship of the total load of the interval to each load point using the deperiodic entropy weight correction algorithm are as follows: Fourier transform is performed on the historical electricity consumption data of each load point within the interval to extract the periodic reference electricity consumption pattern. The deviation between the historical electricity consumption data and the reference electricity consumption pattern is calculated to obtain the deperiodic deviation sequence. The corrected information entropy of each load point is calculated based on the deperiodic deviation sequence of each load point, and the load points are divided into different electricity consumption behavior pattern categories by an unsupervised clustering algorithm. Based on the average entropy value of each cluster category, the entropy-sensitive correction coefficient is obtained through a normalization function; By combining the corrected information entropy and the entropy sensitivity correction coefficient, the allocation weight of each load point is calculated, and the allocation relationship of the total load of the interval to each load point is established.

5. The dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure as described in claim 4, is characterized in that... The specific steps for obtaining the current change time-series data are as follows: Based on the protection topology model, the tie switch is identified as the closing point and the sectionalizing switch is identified as the unclosing point. Using the aforementioned interval load distribution model, the load is redistributed after the closing of the loop point and the opening of the loop point, and the load current value of each interval is calculated after the load transfer. Based on the load current value, it is mapped to the protection device on the transfer path to generate current change timing data.

6. The dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure as described in claim 5, is characterized in that... The specific steps for calculating and verifying the protection settings are as follows: Based on the hierarchical relationship of protection equipment, the theoretical protection settings of each protection equipment are calculated according to the principle that the protection settings decrease as the level increases; Obtain the current protection settings of each protection device, and calculate the verification threshold based on the current protection settings and preset verification coefficients; The current change time series data during the load transfer process is compared with the theoretical protection setting and the verification threshold to generate the verification result.

7. The dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure as described in claim 6, is characterized in that... The specific steps for dynamically adjusting the protection settings using the impact tolerance coefficient to generate the final protection settings are as follows: The temporary protection setting before the switchover is generated by weighting the current operating current value of the loop-breaking point switch with the preset impact tolerance coefficient. The temporary protection setting is sent to the loop-breaking point switch to perform the reversal operation; After the reversal is completed, the operating protection settings of the loop break point switch are recalculated according to the load distribution and hierarchical relationship, and the replacement temporary settings are issued.

8. The dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure as described in claim 7, is characterized in that... The specific steps for issuing the final protection setting to the protection device and triggering the load transfer operation are as follows: The adjusted protection settings are sent to the corresponding protection devices through the protection control system. After the set value takes effect, the operation sequence of closing and then opening is executed: first close the tie switch to achieve closed-loop operation, and then open the unclosing point sectionalizing switch to complete the load transfer.

9. The dynamic protection setting coordination method for a distribution network with a 30-degree phase angle difference and seamless loop closure as described in claim 8, is characterized in that, The process of issuing the final protection settings to the protection equipment and triggering the load transfer operation also includes dynamically updating the protection topology model and the hierarchical relationship of the protection equipment. The specific steps are as follows: Based on changes in the state of distribution network switches, identify and locate localized areas of topological change. The feeder connection relationship within the changing area is analyzed in real time, and the protection topology model is updated accordingly. The hierarchical relationship of protection devices on the changing feeder is updated using a graph traversal algorithm.

Images