An overload protection device and method for a ring main unit

Abstract

The present invention discloses an overload protection device and method for a ring main unit, and relates to the technical field of power system protection. The method comprises: a distributed power grid-connected topology construction module establishes a power grid-connected topology of a target ring main unit; an effective power data determination module samples real-time power grid data, decomposes signal frequency bands, and screens effective power data; a circuit equivalent processing module performs circuit equivalent processing on the grid-connected topology based on effective power data to form an equivalent topology; an adaptive setting calculation module performs adaptive calculation based on the equivalent topology and the overload protection module to generate an overload protection strategy; an overload protection management module performs load cutover and switch management on the ring main unit based on the protection strategy to ensure safe operation of the power grid. The invention solves the technical problem that the overload protection parameters cannot be dynamically adjusted according to the real-time power grid status in the prior art, resulting in untimely and inaccurate overload protection response, and achieves the technical effect of real-time monitoring of the power grid status and dynamic adjustment of the overload protection parameters.

Description

Technical Field

[0001] The present application relates to the technical field of power system protection, and in particular to an overload protection device and method for a ring main unit. Background Art

[0002] As the requirements for stability and reliability of power systems continue to increase, traditional overload protection devices often rely on preset static parameters to respond to changes in grid load. However, the dynamic fluctuations and sudden failures of grid loads make it impossible for this traditional protection method to respond to changes in grid status in a timely and accurate manner, resulting in insufficient sensitivity and accuracy of overload protection, which in turn affects the stability and safety of the system. Especially in the context of distributed power access and grid intelligence, traditional overload protection cannot adapt to load changes in real time, nor can it accurately predict overload conditions. For this reason, there is an urgent need for a new type of overload protection technology that can dynamically adjust protection parameters based on real-time grid data and accurately predict overload conditions, so as to improve the operating efficiency of the grid, reduce equipment losses and failures, and enhance the stability and reliability of the grid.

[0003] At present, there is a technical problem in the relevant technologies that the overload protection parameters cannot be dynamically adjusted according to the real-time power grid status, resulting in untimely and inaccurate overload protection response. Summary of the invention

[0004] The present application provides an overload protection device and method for a ring main unit, thereby solving the technical problem in the prior art that overload protection parameters cannot be dynamically adjusted according to the real-time power grid status, resulting in untimely and inaccurate overload protection response.

[0005] The present application provides an overload protection device for a ring main unit, comprising:

[0006] A distributed power grid-connected topology construction module, which is used to establish a distributed power grid-connected topology for the connected load terminal of the target ring network cabinet; an effective power data determination module, which is used to determine the grid-connected power data based on real-time grid-connected power data sampling and decompose it based on the signal frequency band to determine the effective power data, wherein the frequency band decomposition of noise and useful signals is used as the standard; a circuit equivalent processing module, which is used to perform circuit equivalent processing on the distributed power grid-connected topology based on the effective power data to determine the equivalent grid-connected topology, wherein the equivalent processing method includes effective circuit equivalence and temperature rise conversion equivalence; an adaptive setting calculation module, which is used to identify the equivalent grid-connected topology, and perform adaptive setting calculation in combination with the overload protection module to determine the overcurrent protection action constant and generate an overload protection strategy; an overload protection management module, which is used to perform overload protection management on the target ring network cabinet based on the overload protection strategy, wherein the overload protection management includes load cutover management and multi-thread switch management under closed-loop operation.

[0007] The present application also provides an overload protection method for a ring main unit, comprising:

[0008] A distributed power grid-connected topology is established for the connected load terminals of the target ring main unit; based on real-time grid-connected power data sampling, the grid-connected power data is determined and decomposed based on the signal frequency band to determine the effective power data, wherein the frequency band decomposition of noise and useful signals is used as a standard; based on the effective power data, the distributed power grid-connected topology is subjected to circuit equivalent processing to determine the equivalent grid-connected topology, wherein the equivalent processing method includes effective circuit equivalent and temperature rise conversion equivalent; the equivalent grid-connected topology is identified, and in combination with the overload protection module, an adaptive setting calculation is performed to determine the overcurrent protection action constant and generate an overload protection strategy; based on the overload protection strategy, overload protection management is performed on the target ring main unit, wherein the overload protection management includes load cutover management and multi-thread switch management under closed-loop operation.

[0009] An overload protection device and method for a ring main unit proposed in this application are as follows: first, a distributed power grid-connected topology construction module establishes a power grid-connected topology of a target ring main unit; an effective electrical data determination module samples real-time power grid data, decomposes signal frequency bands, and filters effective electrical data; a circuit equivalent processing module performs circuit equivalent processing on the grid-connected topology based on effective electrical data to form an equivalent topology; an adaptive setting calculation module performs adaptive calculation according to the equivalent topology and the overload protection module to generate an overload protection strategy; an overload protection management module performs load shedding and switch management on the ring main unit based on the protection strategy to ensure safe operation of the power grid, thereby achieving the technical effect of real-time monitoring of the power grid status and dynamically adjusting the overload protection parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the accompanying drawings of the embodiment of the present invention will be briefly introduced below. A flow chart is used in the present application to illustrate the operations performed by the system according to the embodiment of the present application. It should be understood that the preceding or following operations are not necessarily performed accurately in order. On the contrary, various steps can be processed in reverse order or simultaneously as needed. At the same time, other operations can also be added to these processes, or one or more operations can be removed from these processes.

[0011] Figure 1 A schematic structural diagram of an overload protection device for a ring main unit provided in an embodiment of the present application.

[0012] Figure 2 A flow chart of an overload protection method for a ring main unit provided in an embodiment of the present application.

[0013] Explanation of the reference numerals: distributed power grid-connected topology building module 10 , effective power data determination module 20 , circuit equivalent processing module 30 , adaptive setting calculation module 40 , overload protection management module 50 . DETAILED DESCRIPTION

[0014] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below.

[0015] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0016] In the following description, reference is made to "some embodiments", which describe a subset of all possible embodiments, but it is understood that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict, and the terms "first\second" involved are merely to distinguish similar objects and do not represent a specific ordering of objects. The terms "including" and "having" and any variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products, or devices. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by technicians in the technical field of this application. The terms used herein are for the purpose of describing the embodiments of the present application only.

[0017] The present application embodiment provides an overload protection device for a ring main unit, such as Figure 1 As shown, the device comprises:

[0018] A distributed power grid-connected topology construction module 10, the distributed power grid-connected topology construction module 10 is used to establish a distributed power grid-connected topology for the connected load terminals of the target ring network cabinet. Specifically, the distributed power grid-connected topology construction module 10 first traverses and queries the connected load terminals of the target ring network cabinet, collects information such as load type, rated power, voltage level, current characteristics and operation time rules and organizes them into a library, analyzes the type of distributed power supply, rated power output capacity, voltage output range and stability, output current characteristics, etc. and integrates them, and then draws the topology structure in a graphical manner based on the load terminal information and the distributed power supply characteristic information, marks the power supply output, ring network cabinet and load connection nodes, considers the optimization of the electrical parameters of the transmission line, arranges the connection order according to the importance and characteristics of the load, and sets the energy storage device or control strategy node for the intermittent and volatile distributed power supply, thereby constructing a complete and optimized distributed power grid-connected topology structure.

[0019] The effective electric data determination module 20 is used to determine the grid-connected electric data according to the real-time grid-connected electric data sampling, and decompose it based on the signal frequency band to determine the effective electric data, wherein the frequency band decomposition of noise and useful signals is used as the standard. Specifically, the effective electric data determination module 20 deploys current transformers, voltage transformers, and power sensors at key positions of the target ring network cabinet to collect real-time grid-connected electric data, analyzes historical sampling data, and uses spectrum analysis and other technologies to find out the frequency band intervals of noise (such as 10kHz-100kHz high frequency bands) and useful signals (such as 50Hz or 60Hz power frequency and its nearby frequency bands) to determine the decomposition standard, uses Fourier transform to convert the grid-connected electric data to the frequency domain, and filters out the noise frequency band components according to the frequency band interval, and then inversely transforms it back to the time domain and performs rationality checks and optimization processing, and finally determines the effective electric data to provide reliable data support for subsequent work.

[0020] In a possible implementation, the effective electric data determination module 20 further includes: an electric data frequency feature determination unit, which is used to interact with historical sampling data, and mine noise frequency band intervals and useful signal frequency band intervals as electric data frequency features. Specifically, the electric data frequency feature determination unit interacts with historical sampling data. Data is retrieved from a database storing a large amount of past grid-connected electric data, and the historical sampling data covers the electrical parameter information of the ring network cabinet in different operating periods, different load conditions and different external environments. The historical data is analyzed by using signal analysis algorithms, such as spectrum analysis, time-frequency analysis and other technical means. During the analysis process, the frequency distribution of the signal is focused on, and the noise frequency band interval is determined by statistical analysis of different frequency components. For example, after analyzing a large amount of data, it is found that in some high-frequency bands (such as 20kHz-80kHz), the signal shows irregular fluctuations and the energy distribution is relatively dispersed, which is inconsistent with the electric energy signal characteristics of the normal operation of the ring network cabinet, and the frequency band is determined to be a noise frequency band interval. At the same time, the useful signal frequency band is determined. For conventional power systems, the power frequency (50Hz or 60Hz) and the signals within a certain bandwidth nearby are the main useful signal carrying frequency bands, because they contain the key information of power transmission required for the normal operation of the ring network cabinet. The mined noise frequency band and useful signal frequency band are recorded as the frequency characteristics of electrical data, providing a basic basis for the subsequent construction of the intrinsic mode function.

[0021] An intrinsic mode function construction unit, the intrinsic mode function construction unit is used to construct an intrinsic mode function based on the frequency characteristics of the electrical data, wherein the intrinsic mode function characterizes the sub-mode of signal decomposition. Specifically, the intrinsic mode function construction unit constructs the intrinsic mode function based on the determined frequency characteristics of the electrical data. First, the boundary conditions of the function are determined according to the noise frequency band interval and the useful signal frequency band interval. For example, the attenuation characteristics of the function in the noise frequency band interval are set so that it can effectively suppress the signal components in the frequency band. For the useful signal frequency band interval, the design function has good fidelity in the interval and can accurately decompose and extract the signal sub-modes in the frequency band. Then, the intrinsic mode function is constructed using the relevant principles of the empirical mode decomposition (EMD) algorithm. The EMD algorithm decomposes the signal based on the local extreme points and envelope of the signal. On this basis, the intrinsic mode function, combined with the determined frequency band characteristics, constructs a function form that can decompose the grid-connected electrical data into multiple sub-modes through iterative calculation. For example, for a grid-connected power data sample containing noise and useful signals, the intrinsic mode function can decompose it into sub-modes corresponding to different frequency ranges, such as low-frequency useful signal sub-mode, high-frequency noise sub-mode, etc. Each sub-mode has relatively independent frequency characteristics, thus providing an accurate decomposition tool for subsequent signal processing.

[0022] A signal decomposition and reconstruction unit, the signal decomposition and reconstruction unit is used to construct a signal processing unit based on the intrinsic mode function, perform signal decomposition screening and signal reconstruction on the grid-connected power data, and determine the effective power data, wherein the signal processing unit includes a bidirectional signal decomposition branch. Specifically, the signal decomposition and reconstruction unit constructs a signal processing unit based on the intrinsic mode function, and the unit includes a bidirectional signal decomposition and reconstruction branch. In the signal decomposition branch, after the grid-connected power data is input into the signal processing unit, it is decomposed using the intrinsic mode function. According to the rules set by the intrinsic mode function, the grid-connected power data is decomposed into multiple sub-modal signals. For example, a complex grid-connected power data may be decomposed into several sub-modal signals in different frequency ranges, such as sub-modal signals in the useful signal frequency band and sub-modal signals in the noise frequency band. Then, in the signal screening link, according to the previously determined noise frequency band interval, the sub-modal signals in the noise frequency band are eliminated, and only the sub-modal signals in the useful signal frequency band are retained. In the signal reconstruction branch, the useful sub-modal signals after screening are reconstructed. By using reconstruction algorithms such as weighted summation, the retained useful sub-modal signals are combined according to their importance or energy proportion in the original signal to restore effective electrical data. Through this two-way signal processing process, the noise interference in the grid-connected electrical data is effectively removed, and effective electrical data that can accurately reflect the operating status of the ring main unit is obtained, providing a reliable data basis for subsequent circuit equivalent processing and other links.

[0023] In a possible implementation, the signal decomposition and reconstruction unit further includes: a frequency band interval identification subunit, and the frequency band interval identification subunit is used to identify and decompose the grid-connected power data based on the frequency band interval according to the intrinsic mode function, and determine N decomposition signals. Specifically, the frequency band interval identification subunit carries out frequency band interval identification and decomposition work on the grid-connected power data according to the intrinsic mode function. The intrinsic mode function is constructed based on the previous analysis of the frequency characteristics of the power data, and decomposes the complex signal according to specific frequency band rules. When the grid-connected power data is input, the intrinsic mode function gradually decomposes the grid-connected power data into multiple sub-signals by analyzing the local characteristics of the signal and the preset frequency band decomposition rules. For example, for a grid-connected power data containing multiple frequency components, the intrinsic mode function may decompose it into sub-signals of different frequency band ranges according to the characteristics such as the high and low frequencies and the periodicity of the signal, and the sub-signals together constitute the N decomposition signals. During the decomposition process, the boundary conditions of the previously determined noise frequency band interval and the useful signal frequency band interval will be fully considered, so that the decomposed signal can be clearly divided into the corresponding frequency band category, providing convenience for subsequent screening work.

[0024] The decomposed signal screening subunit is used to traverse the N decomposed signals, screen out the decomposed signals in the noise frequency band interval, and determine the useful decomposed signals. Specifically, the decomposed signal screening subunit performs a traversal operation on the obtained N decomposed signals. During the traversal process, focus on the frequency band interval in which each decomposed signal is located. For the decomposed signals in the noise frequency band interval, according to the noise frequency band range previously determined by historical data mining and analysis, high frequency bands such as 10kHz-100kHz are determined to be noise frequency bands, and the decomposed signals in the noise frequency band are screened out. Through screening, the noise interference components in the grid-connected power data can be effectively removed, and what is retained is the decomposed signal located in the useful signal frequency band interval, that is, the useful decomposed signal is determined. The useful decomposed signal can more accurately reflect the electrical signal information related to the actual operating status of the ring network cabinet, laying the foundation for the determination of the final effective electrical data.

[0025] The signal reconstruction processing subunit is used to perform signal reconstruction processing on the useful decomposition signal to determine the effective electrical data. Specifically, the signal reconstruction processing subunit performs signal reconstruction processing on the useful decomposition signal obtained by screening. The characteristics of the useful decomposition signal are analyzed, including key parameters such as the amplitude, phase, and frequency of the signal. Then, a suitable reconstruction algorithm is adopted according to the parameters, such as a signal reconstruction algorithm based on the least squares method or a reconstruction algorithm based on Fourier series expansion. Taking the least squares method as an example, by constructing an error function, the error between the reconstructed signal and the useful decomposition signal is minimized, thereby determining the coefficients and expressions of the reconstructed signal. After being processed by the reconstruction algorithm, the useful decomposition signal is recombined into a complete signal, and the signal is the effective electrical data that removes noise interference and can truly reflect the operating status of the ring network cabinet. The effective electrical data will be used in subsequent important links such as circuit equivalent processing and adaptive setting calculation, providing reliable data support for the overload protection system of the entire ring network cabinet, ensuring that the system can accurately judge the operating status of the ring network cabinet and take effective protection measures in time.

[0026] The circuit equivalent processing module 30 is used to perform circuit equivalent processing on the distributed power grid-connected topology based on the effective electrical data, and determine the equivalent grid-connected topology, wherein the equivalent processing method includes effective circuit equivalent and temperature rise conversion equivalent. Specifically, the circuit equivalent processing module 30 analyzes the electrical data variables in the effective electrical data to locate the nodes of the distributed power grid-connected topology, determines the position according to the change mode and mutual correlation of electrical parameters such as current and voltage at the node, and then retains the node to perform an equivalent processing on the topology, simplifies the circuit according to Kirchhoff's law, merges or equates the components that have little impact on the overall performance, and constructs an effective equivalent circuit. Then, based on the current information in the electrical data variables combined with thermal principles, the heat generation and accumulation of different nodes are calculated according to Joule's law, and the temperature rise equivalent circuit is constructed using equivalent thermal resistance and heat capacitance components. Finally, the distributed power grid-connected topology, the effective equivalent circuit, and the temperature rise equivalent circuit are mapped and integrated to determine the equivalent grid-connected topology that can fully reflect the actual operating status, providing a basis for subsequent work.

[0027] In a possible implementation, the circuit equivalent processing module 30 further includes: a grid-connected topology node positioning unit, which is used to traverse the effective electrical data and locate the grid-connected topology node with an electrical data variable, wherein the electrical data variable represents the load change of the upper monitoring node and the real-time monitoring node. Specifically, the grid-connected topology node positioning unit first traverses the effective electrical data. The effective electrical data contains rich electrical parameter information, such as current, voltage, power, etc., and the data exists in the form of a time series or other data structure. During the traversal process, the electrical data variable is focused on, which represents the load change of the upper monitoring node and the real-time monitoring node. By analyzing the electrical parameter changes of the nodes at different time points, such as the situation where the current of the upper monitoring node gradually increases and the voltage of the real-time monitoring node fluctuates and decreases, combined with the circuit principle and topological structure knowledge, the node position corresponding to the change is determined. Due to the different connection relationships and functions of different nodes in the circuit, their load changes will show specific laws and correlations in the effective electrical data. Accurately locate each node in a complex distributed power grid-connected topology, laying the foundation for the subsequent equivalent circuit construction.

[0028] An effective equivalent circuit determination unit, the effective equivalent circuit determination unit is used to retain the grid-connected topology node, perform an equivalent process on the distributed power grid-connected topology, and determine an effective equivalent circuit. Specifically, after obtaining the located grid-connected topology node, the effective equivalent circuit determination unit performs an equivalent process on the distributed power grid-connected topology. First, the previously determined grid-connected topology node is completely retained, because the node is the key connection point and information convergence point of the circuit. Then, according to the basic theory of the circuit, such as Kirchhoff's current law and voltage law, the components and branches in the original topology are simplified. For some components such as resistors and capacitors that have little effect on the electrical performance of the overall circuit, they are merged or replaced by equivalent. For example, multiple small resistors with similar resistance values ​​in parallel are equivalent to one resistor, or small capacitors in series are equivalent to one capacitor. In this way, without changing the main electrical characteristics of the circuit, the complexity of the circuit is reduced, and an effective equivalent circuit is constructed. Such an effective equivalent circuit is more convenient for subsequent analysis and calculation and fusion processing with other equivalent circuits.

[0029] The temperature rise equivalent circuit determination unit is used to perform secondary equivalent processing on the effective equivalent circuit based on the electrical data variable, and determine the temperature rise equivalent circuit based on heat accumulation, wherein the temperature rise equivalent circuit is identified by a linear relationship of node temperature rise, and protection prediction is performed based on the linear relationship of temperature rise. Specifically, the temperature rise equivalent circuit determination unit performs secondary equivalent processing on the effective equivalent circuit based on the electrical data variable. Since the current passing through the component will generate heat when the circuit is running, the heat accumulation will affect the circuit performance. The current information in the electrical data variable is used in combination with thermal principles, such as Joule's law (Q=I²Rt), to calculate the heat generation of the components at different nodes. Considering the heat dissipation characteristics of the component, such as thermal resistance, thermal capacitance and other parameters, the temperature rise of the node is determined. A temperature rise equivalent circuit based on heat accumulation is constructed, in which equivalent thermal resistance, thermal capacitance and other components are used to reflect the heat accumulation effect. In addition, the temperature rise equivalent circuit identifier has a linear relationship of node temperature rise, that is, considering that the node has a certain temperature rise trend during normal operation, when the load changes, its temperature rise condition will change according to a certain rule based on the original trend. Through the analysis of historical data and theoretical calculations, the temperature change curve after the load change is determined. Based on this linear relationship of temperature rise, protection prediction can be carried out, and the overload risk caused by temperature rise can be evaluated in advance, so that protection measures can be taken in time.

[0030] An equivalent grid-connected topology determination unit, the equivalent grid-connected topology determination unit is used to map the distributed power grid-connected topology-effective equivalent circuit-temperature rise equivalent circuit as the equivalent grid-connected topology. Specifically, the equivalent grid-connected topology determination unit maps and integrates the distributed power grid-connected topology, the effective equivalent circuit, and the temperature rise equivalent circuit to determine the equivalent grid-connected topology. The electrical connection structure of the original distributed power grid-connected topology, the simplified electrical characteristics of the effective equivalent circuit, and the thermal characteristics of the temperature rise equivalent circuit are organically combined. In the equivalent grid-connected topology, it is possible to clearly see the transmission path of electric energy and the equivalent relationship of electrical components, and to understand the heat accumulation and temperature rise trend at different nodes. The equivalent grid-connected topology reflects the actual operating state of the ring network cabinet after the distributed power supply is connected to the grid, and provides a comprehensive and accurate circuit model basis for subsequent adaptive setting calculations, overload protection strategy formulation, etc., which helps to improve the operating safety and reliability of the entire ring network cabinet system.

[0031] The adaptive setting calculation module 40 is used to identify the equivalent grid-connected topology, and in combination with the overload protection module, perform adaptive setting calculation, determine the overcurrent protection action constant, and generate an overload protection strategy. Specifically, the adaptive setting calculation module 40 identifies the equivalent grid-connected topology, analyzes its structure and electrical thermal state, and determines an overload protection mechanism including multi-thread switch protection and load cutover protection under closed-loop operation. Subsequently, based on the data of the equivalent grid-connected topology, the overload key position is determined in the temperature rise equivalent circuit according to the linear relationship between heat accumulation and node temperature rise, and is converted into setting protection data including grid-connected topology nodes and setting quantities through equivalent mapping. Subsequently, based on this data and the equivalent mapping, a load cutover decision is made under the first adaptive protection mode, and the cutover load quantity and the corresponding branch and protection action setting are calculated to determine the first overload protection strategy. It is then determined whether it satisfies the setting protection data. If not, the second adaptive protection mode is activated, and the overload thread is located by analyzing the current distribution and the switch tube shutdown parameters are determined to form a second overload protection strategy. Finally, the two strategies are integrated to generate an overload protection strategy that can automatically adapt to the overload degree and working conditions, thereby ensuring the safe and reliable operation of the ring network cabinet.

[0032] In a possible implementation, the adaptive setting calculation module 40 further includes: an overload protection mechanism determination unit, the overload protection mechanism determination unit is used to determine the overload protection mechanism, wherein the overload protection mechanism includes multi-thread switch protection under closed-loop operation and load cutover protection. Specifically, the overload protection mechanism determination unit analyzes the closed-loop operation condition of the ring network cabinet. During closed-loop operation, the power network structure of the ring network cabinet is more complex, multiple power lines are interconnected, and electric energy flows between different paths. In this case, in order to effectively deal with the overload risk, an overload protection mechanism is determined. Among them, the multi-thread switch protection mechanism is a key component. The multi-thread switches are distributed on different circuit branches of the ring network cabinet, and can monitor the electrical parameters such as current and voltage of the branches in real time. When an overload occurs in a circuit branch, that is, the current exceeds the preset safety threshold, the corresponding multi-thread switch can respond quickly, and decide whether to cut off the branch circuit according to the preset logic and control strategy to prevent the overload current from causing further damage to the entire ring network cabinet system. At the same time, load cutover protection is also an important protection means. By monitoring and analyzing the operating status of each load end of the ring main unit, when an overload occurs, part of the load will be transferred from the overloaded circuit branch to a relatively idle branch or a branch that can withstand additional load, based on the importance of the load, the operating characteristics and the load conditions of other branches, thereby balancing the loads of each branch and maintaining the stable operation of the ring main unit.

[0033] An overload protection strategy determination unit, the overload protection strategy determination unit is used to use the load cutover protection as the first adaptive protection mode, the multi-thread switch protection as the second adaptive protection mode, and coordinate the first adaptive protection mode and the second adaptive protection mode to determine the overload protection strategy. Specifically, the overload protection strategy determination unit evaluates the load distribution of the ring network cabinet. Collect information such as the power demand, operating time, and importance level of each load terminal to build a detailed load information database. When an overload signal is detected, an analysis is performed based on the database to determine the load range and target circuit branch that can be cutover. For example, for some non-critical and adjustable loads, such as spare equipment loads in some industrial production or non-peak loads in commercial places, through an intelligent control device, it is switched from the overloaded main circuit branch to the spare circuit branch or other branches with lighter loads. In this process, it is necessary to accurately calculate the load amount to be cutover to ensure that the overload pressure can be effectively alleviated without causing excessive impact on the normal operation of the cutover load. At the same time, the corresponding protection action setting is determined, such as the current and voltage fluctuation range limit and the switching time control during the load cutover process, so as to form the core content of the first overload protection strategy. With multi-threaded switch protection as the second adaptive protection mode, after the first overload protection strategy is implemented, its effect is monitored and evaluated in real time. If it is found through the monitoring of electrical parameters such as current and voltage that the first overload protection strategy fails to control the overload situation within a safe range, that is, the overload degree still exceeds the preset threshold or has a trend of further deterioration, the second adaptive protection mode is started at this time. By conducting a detailed analysis of the current distribution of each circuit branch of the ring network cabinet, the monitoring data and intelligent control algorithm of the multi-threaded switch are used to quickly locate the overload thread, that is, determine the circuit branch through which the overload current mainly flows. Then, according to the preset switch tube shutdown logic, the switch tubes that need to be shut down and their shutdown sequence and time interval and other parameters are determined. For example, in some complex ring network cabinet networks, it may be necessary to shut down the switch tubes close to the power supply end first to avoid problems such as current backflow, and then shut down other related switch tubes in turn to ensure that the overload circuit can be safely and quickly cut off. The first overload protection strategy and the second overload protection strategy are integrated in a coordinated manner. According to different overload degrees and working conditions, detailed strategy switching rules and collaborative working methods are formulated to form a complete overload protection strategy. For example, in the case of slight overload, the load cutover protection strategy is used first for load allocation; when there is moderate overload and the load cutover effect is not good, the multi-threaded switch protection strategy is gradually introduced for assistance; in the case of severe overload, the multi-threaded switch protection strategy is quickly started to decisively cut off the overload circuit, and the subsequent load is redistributed and adjusted in combination with the load cutover protection strategy, so as to comprehensively guarantee the safe and stable operation of the ring network cabinet during the closed-loop operation process.

[0034] In a possible implementation, the overload protection strategy determination unit further includes: a setting protection data determination subunit, the setting protection data determination subunit is used to identify the equivalent grid-connected topology, perform over-protection positioning and equivalent mapping under the temperature rise equivalent circuit, and determine the setting protection data, wherein the setting protection data includes the grid-connected topology node and the setting value. Specifically, the setting protection data determination subunit traverses and identifies the equivalent grid-connected topology. The structure of the equivalent grid-connected topology is analyzed, including the connection relationship of each node, the equivalent parameters of the components, and the thermal characteristics reflected by the temperature rise equivalent circuit. On the basis of the temperature rise equivalent circuit, over-protection positioning is performed according to the heat accumulation and the linear relationship between the node temperature rise. By calculating the heat generated by the current passing through the component in the circuit and combining the heat dissipation characteristics of the component, the key position that is prone to overheating or overcurrent risk under overload conditions is determined, and the position is usually the node or component where the current is large and the heat dissipation condition is relatively poor. Then, equivalent mapping is performed to convert the key position information into the grid-connected topology node information, and the setting value related thereto is determined, such as the current threshold of overcurrent protection, the temperature threshold of temperature rise protection, etc. The grid-connected topology nodes and the setting quantities together constitute the setting protection data, which provides a specific data basis for the subsequent formulation of protection strategies.

[0035] The first overload protection strategy determination subunit is used to make a load cutover decision under the first adaptive protection mode based on the setting protection data and the equivalent mapping, and determine the first overload protection strategy, wherein the first overload protection strategy identifies the cutover circuit branch and the protection action setting value. Specifically, the first overload protection strategy determination subunit makes a load cutover decision under the first adaptive protection mode based on the setting protection data and the equivalent mapping relationship. First, according to the load information and the equivalent mapping relationship in the setting protection data, a detailed analysis is performed on the load conditions of each circuit branch of the ring network cabinet. Determine which branches are in an overload state and which branches have remaining load carrying capacity. Then, calculate the load amount to be cutover and the corresponding cutover circuit branch. For example, if the current of a main circuit branch exceeds the overcurrent threshold in the setting protection data, and it is found through analysis that a spare circuit branch has sufficient load carrying margin, it is determined to transfer part of the load of the main circuit branch to the spare circuit branch. In this process, it is also necessary to determine the protection action constant, that is, to clarify the load transfer amount during the load cutover process, such as determining to transfer 30% of the load in the main circuit branch to the backup circuit branch. At the same time, it is also necessary to set parameters such as the current and voltage fluctuation range allowed during the transfer process, so as to determine the first overload protection strategy, which clearly identifies the cutover circuit branch and the protection action constant.

[0036] The second overload protection strategy determination subunit is used to determine whether the first overload protection strategy satisfies the setting protection data. If not, based on the second adaptive protection mode, the overload thread is located and the switch tube is shut down to determine the second overload protection strategy. Specifically, the second overload protection strategy determination subunit first determines whether the first overload protection strategy satisfies the setting protection data. By monitoring the electrical parameters of the ring network cabinet after the implementation of the first overload protection strategy, such as checking whether the current, voltage, temperature, etc. are within the safety range specified by the setting protection data. If not, that is, the overload situation has not been effectively alleviated, the protection action is started based on the second adaptive protection mode. By performing a detailed analysis of the current distribution in the equivalent grid-connected topology, the overload thread is located using current sensors and other equipment, that is, the circuit branch path through which the overload current mainly flows is determined. Then, according to the preset multi-threaded switch control logic, the switch tubes that need to be shut down and their shutdown sequence and time interval and other parameters are determined. For example, in a complex ring main unit network, the upstream switch tube close to the overload source is turned off first to quickly cut off the main source of the overload current. Then, according to the circuit topology and the operation of other branches, the relevant downstream switch tubes are gradually turned off to ensure that the overload circuit can be cut off safely and orderly, thereby determining the second overload protection strategy.

[0037] An overload protection strategy generation subunit, the overload protection strategy generation subunit is used to coordinate the first overload protection strategy with the second overload protection strategy to generate the overload protection strategy. Specifically, the overload protection strategy generation subunit integrates the first overload protection strategy with the second overload protection strategy. According to different overload degrees and working conditions, detailed strategy switching rules and collaborative working methods are formulated. In the case of slight overload, the first overload protection strategy is preferentially adopted for load allocation to achieve optimal utilization of resources and minimize the impact on user power supply. When the overload degree increases and the first overload protection strategy cannot be effectively controlled, the second overload protection strategy is introduced in time to quickly cut off the overload circuit through multi-threaded switch protection to ensure the safety of the ring network cabinet. At the same time, after the second overload protection strategy is implemented, according to the new operating state of the ring network cabinet, the first overload protection strategy is started again to redistribute and adjust the load to maintain the ring network cabinet in a safe and stable state, and finally a complete overload protection strategy is generated to enable it to adapt to the overload protection requirements of the ring network cabinet under various complex operating conditions.

[0038] An overload protection management module 50 is used to perform overload protection management on the target ring main unit based on the overload protection strategy, wherein the overload protection management includes load cutover management and multi-thread switch management under closed-loop operation. Specifically, the overload protection management module 50 first implements protection on the target ring main unit according to the overload protection strategy, synchronously samples the response electrical data when executing load cutover management and multi-thread switch management, operates the switch equipment according to the strategy regulations and monitors the changes in electrical parameters to determine the response topology, then determines the setting amount and setting trend of the response topology, compares the actual electrical parameter value with the strategy setting amount and analyzes the change trend, and generates a feedback protection strategy based on the determination result if the strategy does not meet expectations, such as adjusting the load cutover amount, optimizing the switch control logic or enabling backup measures, etc. Finally, feedback management is implemented based on the feedback strategy, adjustment measures are taken and continuously monitored, and the determination and strategy generation steps are repeated according to the effect to optimize management and ensure the safe and stable operation of the ring main unit and the power system.

[0039] In a possible implementation, the overload protection management module 50 further includes: a response topology determination unit, which is used to execute the overload protection strategy, perform response electrical data sampling, and determine the response topology. Specifically, the response topology determination unit executes the overload protection strategy. In terms of executing load cutover management, the relevant electrical equipment is precisely controlled according to the cutover circuit branches and protection action settings specified in the strategy. For example, when the strategy indicates that a specific load of a heavy-load circuit branch is transferred to another relatively idle branch, the load transfer operation is gradually completed through the intelligent switching device according to the set time sequence and current control parameters. In the execution process of multi-threaded switch management, the switch tube shutdown sequence and time interval specified by the strategy are strictly followed to isolate or reconfigure the overload circuit. At the same time, response electrical data sampling is performed. Using high-precision current transformers, voltage transformers and other sensors, the current, voltage and other electrical parameters of each key node of the ring network cabinet are collected in real time. These sampled data cover the changes in electrical parameters before, during and after the protection strategy is executed. By organizing and analyzing the data, an electrical data model of the actual operating state of the ring main unit under the current protection strategy can be constructed to determine the response topology. The response topology reflects the actual connection state of the internal circuit of the ring main unit, the load distribution of each branch, and the topological structure of the overall electrical operating parameters after the overload protection strategy is implemented, providing basic data support for subsequent response determination.

[0040] A feedback protection strategy generation unit, wherein the feedback protection strategy generation unit is used to make a response judgment on the response topology and generate a feedback protection strategy, wherein the response judgment includes a setting value judgment and a setting trend judgment. Specifically, the feedback protection strategy generation unit first makes a setting value judgment. The setting value judgment is to accurately compare the actual electrical parameter value obtained by sampling the response electrical data with the setting value in the overload protection strategy. For example, for overcurrent protection, check whether the actual current value is within the preset safety current threshold range; for load cutover management, check whether the actual load of each branch is consistent with the target load specified in the strategy. If there is a deviation between the actual electrical parameter value and the setting value, further analyze the degree and nature of the deviation. Make a setting trend judgment. Observe the change trend of the electrical parameters by analyzing the time series of the response electrical data. For example, after the load cutover, monitor the change curve of the current of each branch over time. If the current shows a trend of gradually stabilizing and approaching the reasonable range expected by the strategy, even if the current setting value has not yet fully reached the standard, it can be preliminarily determined to be normal. On the contrary, if the setting quantity temporarily meets the standard, but the trend of the change of the electrical parameters is developing in a direction that is not conducive to stable operation, such as the current fluctuation increases and the load distribution gradually becomes unbalanced, it is determined that feedback is needed. The results of the setting quantity determination and the setting trend determination are combined to generate a feedback protection strategy. The feedback protection strategy includes parameter adjustments to the existing overload protection strategy, such as modifying the ratio of load cutover and optimizing the action time of multi-threaded switches; it involves suggestions for adjusting the status of electrical equipment inside the ring network cabinet, such as fine-tuning the parameters of certain capacitors and inductors to improve the overall electrical performance of the ring network cabinet and ensure its stable operation.

[0041] A feedback management unit, the feedback management unit is used to perform feedback management of overload protection on the target ring main unit based on the feedback protection strategy. Specifically, the feedback management unit performs feedback management of overload protection on the target ring main unit based on the feedback protection strategy. First, the various adjustment measures in the feedback protection strategy are accurately applied to the operation management of the ring main unit. During the implementation process, the operation status of the ring main unit is continuously monitored, and the implementation effect of the feedback strategy is observed through the same electrical data sampling and analysis method as before. If it is found that after the implementation of the feedback strategy, the operation status of the ring main unit gradually stabilizes, the electrical parameters meet the safety requirements and the change trend is good, the current protection strategy and monitoring intensity are continued. However, if there are still problems, such as the setting quantity continues to be substandard or the setting trend is abnormal, the feedback management unit will restart the workflow of the feedback protection strategy generation unit, re-respond and determine and generate a new feedback protection strategy, so that the cycle is repeated, and the overload protection management of the ring main unit is continuously optimized until the ring main unit can operate stably and safely under various working conditions, effectively respond to overload risks, and ensure the reliability and continuity of the entire power system.

[0042] The embodiment of the present application adopts a distributed power grid-connected topology construction module to establish the power grid-connected topology of the target ring main unit; the effective power data determination module samples the real-time power grid data, decomposes the signal frequency band, and filters the effective power data; the circuit equivalent processing module performs circuit equivalent processing on the grid-connected topology based on the effective power data to form an equivalent topology; the adaptive setting calculation module performs adaptive calculation according to the equivalent topology and the overload protection module to generate an overload protection strategy; the overload protection management module performs load cutover and switch management on the ring main unit based on the protection strategy to ensure the safe operation of the power grid, thereby achieving the technical effect of real-time monitoring of the power grid status and dynamically adjusting the overload protection parameters.

[0043] In the above, refer to Figure 1 The present invention describes in detail an overload protection device of a ring main unit according to an embodiment of the present invention. Figure 2 An overload protection method for a ring main unit according to an embodiment of the present invention is described.

[0044] An overload protection method for a ring main unit, such as Figure 2 As shown, the method includes:

[0045] A distributed power grid-connected topology is established for the connected load terminals of the target ring main unit; based on real-time grid-connected power data sampling, the grid-connected power data is determined and decomposed based on the signal frequency band to determine the effective power data, wherein the frequency band decomposition of noise and useful signals is used as a standard; based on the effective power data, the distributed power grid-connected topology is subjected to circuit equivalent processing to determine the equivalent grid-connected topology, wherein the equivalent processing method includes effective circuit equivalent and temperature rise conversion equivalent; the equivalent grid-connected topology is identified, and in combination with the overload protection module, an adaptive setting calculation is performed to determine the overcurrent protection action constant and generate an overload protection strategy; based on the overload protection strategy, overload protection management is performed on the target ring main unit, wherein the overload protection management includes load cutover management and multi-thread switch management under closed-loop operation.

[0046] In a possible implementation, the overload protection method of a ring main unit also includes: traversing the effective electrical data and locating the grid-connected topology node with the electrical data variable, wherein the electrical data variable represents the load changes of the upper monitoring node and the real-time monitoring node; retaining the grid-connected topology node, performing a primary equivalent processing on the distributed power grid-connected topology, and determining an effective equivalent circuit; based on the electrical data variable, performing a secondary equivalent processing on the effective equivalent circuit, and determining a temperature rise equivalent circuit based on heat accumulation, wherein the temperature rise equivalent circuit is marked with a linear relationship of node temperature rise, and protection prediction is performed based on the temperature rise linear relationship; mapping the distributed power grid-connected topology-effective equivalent circuit-temperature rise equivalent circuit as the equivalent grid-connected topology.

[0047] In a possible implementation, the overload protection method of a ring main unit also includes: interacting with historical sampling data, mining noise frequency band intervals and useful signal frequency band intervals as electrical data frequency characteristics; constructing an intrinsic mode function based on the electrical data frequency characteristics, wherein the intrinsic mode function characterizes the sub-mode of signal decomposition; constructing a signal processing unit based on the intrinsic mode function, performing signal decomposition screening and signal reconstruction on the grid-connected electrical data, and determining the effective electrical data, wherein the signal processing unit includes a bidirectional signal decomposition branch.

[0048] In a possible implementation, the overload protection method of a ring main unit further includes: according to the intrinsic mode function, identifying and decomposing the grid-connected power data based on the frequency band interval to determine N decomposition signals; traversing the N decomposition signals, screening out the decomposition signals in the noise frequency band interval to determine the useful decomposition signal; performing signal reconstruction processing on the useful decomposition signal to determine the effective power data.

[0049] In a possible implementation, the overload protection method of a ring network cabinet also includes: determining an overload protection mechanism, wherein the overload protection mechanism includes multi-threaded switch protection and load cutover protection under closed-loop operation; using the load cutover protection as a first adaptive protection method, and using the multi-threaded switch protection as a second adaptive protection method, and coordinating the first adaptive protection method and the second adaptive protection method to determine the overload protection strategy.

[0050] In a possible implementation, the overload protection method of a ring main unit also includes: identifying the equivalent grid-connected topology, performing over-protection positioning and equivalent mapping under the temperature rise equivalent circuit, and determining the set protection data, wherein the set protection data includes the grid-connected topology node and the setting value; based on the set protection data, using the equivalent mapping, making a load cutover decision under the first adaptive protection mode, and determining a first overload protection strategy, wherein the first overload protection strategy is identified with a cutover circuit branch and a protection action constant; determining whether the first overload protection strategy satisfies the set protection data, and if not, locating the overload thread and performing switch tube shutdown processing based on the second adaptive protection mode to determine the second overload protection strategy; and coordinating the first overload protection strategy with the second overload protection strategy to generate the overload protection strategy.

[0051] In a possible implementation, the overload protection method of a ring main unit also includes: executing the overload protection strategy, and sampling the response electrical data to determine the response topology; performing a response judgment on the response topology to generate a feedback protection strategy, wherein the response judgment includes a setting amount judgment and a setting trend judgment; based on the feedback protection strategy, performing feedback management of overload protection on the target ring main unit.

[0052] An overload protection device for a ring main unit provided in an embodiment of the present invention can execute an overload protection method for a ring main unit provided in any embodiment of the present invention, and has functional modules and beneficial effects corresponding to the execution method.

[0053] Although the present application makes various references to certain modules in the device according to the embodiments of the present application, any number of different modules may be used and run on the user terminal and / or server, and the various units and modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the functional units are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0054] The above specific implementation manner does not constitute a limitation to the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application. In some cases, the actions or steps recorded in the present application can be performed in an order different from that in the embodiment and can still achieve the desired results. In addition, the process depicted in the accompanying drawings does not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. An overload protection device for a ring main unit, characterized in that: The device comprises: A distributed power grid-connected topology building module, wherein the distributed power grid-connected topology building module is used to establish a distributed power grid-connected topology for a connected load terminal of a target ring main unit; An effective electric data determination module, the effective electric data determination module is used to determine the grid-connected electric data according to the real-time grid-connected electric data sampling and decompose it based on the signal frequency band to determine the effective electric data, wherein the frequency band decomposition of noise and useful signal is used as the standard; A circuit equivalent processing module, the circuit equivalent processing module is used to perform circuit equivalent processing on the distributed power grid-connected topology based on the effective electrical data, and determine an equivalent grid-connected topology, wherein the equivalent processing method includes effective circuit equivalent and temperature rise conversion equivalent; The temperature rise conversion equivalent is based on the current information in the electrical data variables of the effective electrical data combined with thermal principles, and the heat generation and accumulation of different nodes are calculated according to Joule's law. The temperature rise equivalent circuit is constructed with equivalent thermal resistance and thermal capacitance elements, and finally the distributed power grid-connected topology, effective equivalent circuit, and temperature rise equivalent circuit are mapped and integrated to determine the equivalent grid-connected topology that can fully reflect the actual operating status; An adaptive setting calculation module, which is used to identify the equivalent grid-connected topology, perform adaptive setting calculation in combination with the overload protection module, determine the overcurrent protection action setting value, and generate an overload protection strategy; An overload protection management module, wherein the overload protection management module is used to perform overload protection management on the target ring network cabinet based on the overload protection strategy, wherein the overload protection management includes load cutover management and multi-thread switch management under closed-ring operation.

2. The overload protection device of a ring main unit according to claim 1, characterized in that: The circuit equivalent processing module comprises: A grid-connected topology node locating unit, the grid-connected topology node locating unit is used to traverse the effective electrical data and locate the grid-connected topology node with electrical data variables, wherein the electrical data variables represent load changes of the upper monitoring node and the real-time monitoring node; An effective equivalent circuit determination unit, the effective equivalent circuit determination unit is used to retain the grid-connected topology node, perform an equivalent process on the distributed power grid-connected topology, and determine an effective equivalent circuit; A temperature rise equivalent circuit determination unit, the temperature rise equivalent circuit determination unit is used to perform secondary equivalent processing on the effective equivalent circuit based on the electrical data variable, determine a temperature rise equivalent circuit based on heat accumulation, wherein the temperature rise equivalent circuit is identified with a node temperature rise linear relationship, and perform protection prediction based on the temperature rise linear relationship; An equivalent grid-connected topology determining unit is used to map the distributed power grid-connected topology-effective equivalent circuit-temperature rise equivalent circuit as the equivalent grid-connected topology.

3. The overload protection device for a ring main unit according to claim 1, characterized in that: The effective electrical data determination module comprises: An electrical data frequency feature determination unit, the electrical data frequency feature determination unit is used to interact with historical sampling data, mine noise frequency band intervals and useful signal frequency band intervals as electrical data frequency features; An intrinsic mode function construction unit, the intrinsic mode function construction unit is used to construct an intrinsic mode function based on the frequency characteristics of the electrical data, wherein the intrinsic mode function represents a sub-mode of signal decomposition; A signal decomposition and reconstruction unit is used to construct a signal processing unit based on the intrinsic mode function, perform signal decomposition screening and signal reconstruction on the grid-connected power data, and determine the effective power data, wherein the signal processing unit includes a bidirectional signal decomposition branch.

4. The overload protection device for a ring main unit according to claim 3, characterized in that: The signal decomposition and reconstruction unit comprises: A frequency band interval identification subunit, the frequency band interval identification subunit is used to perform identification and decomposition based on the frequency band interval on the grid-connected power data according to the intrinsic mode function, and determine N decomposition signals; A decomposed signal screening subunit, the decomposed signal screening subunit is used to traverse the N decomposed signals, screen out the decomposed signals in the noise frequency band interval, and determine the useful decomposed signals; A signal reconstruction processing subunit is used to perform signal reconstruction processing on the useful decomposed signal to determine the effective electrical data.

5. The overload protection device for a ring main unit according to claim 1, characterized in that: The adaptive setting calculation module includes: An overload protection mechanism determination unit, the overload protection mechanism determination unit is used to determine an overload protection mechanism, wherein the overload protection mechanism includes multi-thread switch protection under closed-loop operation and load cutover protection; An overload protection strategy determination unit, wherein the overload protection strategy determination unit is used to determine the overload protection strategy by taking the load cutover protection as a first adaptive protection mode and the multi-threaded switch protection as a second adaptive protection mode, and coordinating the first adaptive protection mode and the second adaptive protection mode.

6. The overload protection device for a ring main unit according to claim 5, characterized in that: The overload protection strategy determination unit includes: A setting protection data determination subunit, the setting protection data determination subunit is used to identify the equivalent grid-connected topology, perform over-protection positioning and equivalent mapping under the temperature rise equivalent circuit, and determine the setting protection data, wherein the setting protection data includes the grid-connected topology node and the setting amount; A first overload protection strategy determination subunit, the first overload protection strategy determination subunit is used to make a load cutover decision under the first adaptive protection mode based on the set protection data and the equivalent mapping, and determine a first overload protection strategy, wherein the first overload protection strategy identifies a cutover circuit branch and a protection action setting value; A second overload protection strategy determination subunit, the second overload protection strategy determination subunit is used to determine whether the first overload protection strategy satisfies the setting protection data, if not, based on the second adaptive protection mode, locate the overload thread and perform switch tube shutdown processing to determine the second overload protection strategy; An overload protection strategy generating subunit, wherein the overload protection strategy generating subunit is used to coordinate the first overload protection strategy and the second overload protection strategy to generate the overload protection strategy.

7. The overload protection device for a ring main unit according to claim 1, characterized in that: The overload protection management module includes: A response topology determination unit, the response topology determination unit is used to execute the overload protection strategy, perform response electrical data sampling, and determine a response topology; A feedback protection strategy generating unit, the feedback protection strategy generating unit is used to perform response determination on the response topology and generate a feedback protection strategy, wherein the response determination includes a setting amount determination and a setting trend determination; A feedback management unit, wherein the feedback management unit is used to perform feedback management of overload protection on the target ring main unit based on the feedback protection strategy.

8. A method for overload protection of a ring main unit, characterized in that: The method is applied to an overload protection device of a ring main unit according to any one of claims 1 to 7, and the method comprises: Establish a distributed power grid-connected topology for the connected load terminals of the target ring main unit; According to the real-time grid-connected power data sampling, the grid-connected power data is determined and decomposed based on the signal frequency band to determine the effective power data, wherein the frequency band decomposition of noise and useful signal is used as the standard; Based on the effective electrical data, the distributed power grid-connected topology is subjected to circuit equivalent processing to determine an equivalent grid-connected topology, wherein the equivalent processing method includes effective circuit equivalent and temperature rise conversion equivalent; Identify the equivalent grid-connected topology, combine with the overload protection module, perform adaptive setting calculation, determine the overcurrent protection action setting value, and generate an overload protection strategy; Based on the overload protection strategy, overload protection management is performed on the target ring main unit, wherein the overload protection management includes load cutover management and multi-thread switch management under closed-ring operation.

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