Medium and low voltage collaborative self-healing method and system for rapid power restoration of global users

Abstract

The invention relates to the technical field of medium and low voltage distribution network cooperative self-healing, and provides a medium and low voltage cooperative self-healing method and system for rapid power restoration of global users. Comprising the steps that medium-voltage permanent fault information is received, medium-voltage self-healing is started, fault positioning is carried out, a fault area is remotely controlled and isolated, and remote power recovery is carried out on a medium-voltage non-fault area; the real-time temperature of a distribution transformer low-voltage side wire, the voltage sag duration of a distribution transformer low-voltage bus, the power utilization priority of a user carried by a distribution transformer, the topological distance between a distribution transformer to be subjected to low-voltage transfer and a target transfer distribution transformer and the actual load current of the distribution transformer to be subjected to low-voltage transfer are collected, and dynamic bearing checking of distribution transformer low-voltage transfer is achieved; based on medium-voltage fault information and the acquired parameters, rapid self-healing power restoration of global users under the fault condition is realized through linkage cooperation of medium-voltage self-healing and low-voltage self-healing, and meanwhile, overload tripping of low-voltage transfer can be effectively reduced and power restoration efficiency and power supply stability of the global users can be improved by realizing dynamic bearing checking of distribution transformer low-voltage transfer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medium and low voltage distribution network cooperative self-healing, and particularly relates to a medium and low voltage cooperative self-healing method and system for global user fast power recovery. BACKGROUND

[0002] Distribution network self-healing is a core technology to improve power supply reliability. Current mainstream solutions focus on medium voltage side fault handling, and through locating and isolating the fault area, the power supply in the non-fault area is restored. However, there are significant technical shortcomings: the low voltage distribution transformer users in the medium voltage fault area cannot be recovered by medium voltage self-healing, forming a "medium voltage self-healing recovery dead zone". Such users need to rely on manual on-site operation to recover, and the power outage time is as long as several hours, which seriously affects the global recovery efficiency.

[0003] At the same time, a few solutions involving low voltage transfer supply use the static rated current of the distribution transformer low voltage side as the safety check basis, without combining dynamic parameters such as real-time temperature of the conductor, voltage sag duration of the low voltage bus, etc. In extreme environments, the conductor carrying capacity fluctuates greatly, and the deviation between the static limit value and the actual carrying capacity is significant, which easily leads to overload trip after transfer supply, further prolonging the recovery time.

[0004] Therefore, the existing technology cannot cover the recovery demand of low voltage users in the fault area, and the low voltage check method has safety risks. It is urgent to extend the self-healing capability to the low voltage side and build a medium and low voltage cooperative self-healing solution. Through the cooperative linkage of medium voltage self-healing and low voltage self-healing, the problems of medium voltage fault area recovery dead zone and low voltage transfer supply dynamic bearing check are solved, and the global user fast recovery is realized. SUMMARY

[0005] The purpose of the present application is to provide a medium and low voltage cooperative self-healing method for global user fast recovery, comprising: S1, receiving medium voltage permanent fault information, locating the fault on the medium voltage side and remotely isolating the fault area, and remotely recovering the power supply in the medium voltage non-fault area; S2, collecting real-time temperature of the low voltage side conductor, voltage sag duration of the low voltage bus, user electricity priority of the distribution transformer, topology distance between the to-be-transferred distribution transformer and the target transferred distribution transformer, and actual load current of the to-be-transferred distribution transformer, and realizing dynamic bearing check of the distribution transformer low voltage transfer supply; S3, based on the medium voltage permanent fault information and the above-mentioned collected parameters, for the fault area, determining the set of voltage loss distribution transformers, performing low voltage self-healing start boundary check of the voltage loss distribution transformers, and determining the set of to-be-low-voltage-self-healing distribution transformers; S4, performing low voltage topology analysis on the set of to-be-low-voltage-self-healing distribution transformers to identify the distribution transformer groups connected to each other, and searching for a low voltage direct transfer power recovery scheme in units of distribution transformer groups; S5, priority ranking and power flow checking are performed on the direct transfer scheme, and low-voltage automatic transfer is realized for low-voltage distribution transformers in the loss of voltage area through low-voltage self-healing to restore power supply to low-voltage users in the fault area; S6, the transfer scheme is executed according to the rule of parallel sequence between distribution transformer groups and descending priority within the distribution transformer group, if the switch remote control fails, the above-mentioned parameters are re-collected and the low-voltage transfer scheme is updated until the power supply to all users is restored.

[0006] Preferably, S2 specifically comprises: the real-time temperature of the conductor is obtained through a temperature sensor, the duration of the low-voltage bus voltage sag is obtained through a power quality monitoring terminal, the user power consumption priority is obtained from a power marketing system, the topological distance is obtained from a distribution network GIS system, and the actual load current is obtained through a low-voltage automation terminal; the parameter collection process is started synchronously with the fault isolation step on the medium-voltage side, and the collection frequency is set to 1 time per second to ensure the timeliness of the parameters; after collection, the parameters are standardized and processed in format, and are converted into a numerical format recognizable by the system for subsequent distribution transformer set analysis.

[0007] Further preferably, S3 specifically comprises: analyzing the list of non-restored distribution transformers contained in the medium-voltage fault information, extracting the distribution transformer number, the distribution transformer to which it belongs, and the load type information, and forming the loss of voltage distribution transformer set; selecting distribution transformers with low-voltage automation terminals, available low-voltage tie switches, and normal communication channels from the loss of voltage distribution transformer set, excluding distribution transformers without low-voltage transfer conditions, and forming the low-voltage self-healing distribution transformer set; pre-checking each low-voltage self-healing distribution transformer, the pre-checking content including whether the distribution transformer is in a locked state, whether the low-voltage main switch is in a closed position, whether there is a fault signal in the low-voltage main switch, and whether the dynamic load capacity of the distribution transformer meets the basic load requirement, and all pre-checking conditions are met. The distribution transformer is included in the low-voltage self-healing distribution transformer set.

[0008] Further preferably, in S4, the step of searching for a low-voltage direct transfer scheme comprises: calling a low-voltage topology database of the distribution network, obtaining the low-voltage tie switch connection relationship, conductor type, and power supply radius information of all distribution transformers in the low-voltage self-healing distribution transformer set; based on the tie switch connection relationship, dividing the distribution transformers with direct low-voltage tie paths into the same distribution transformer group; searching for a direct transfer scheme in each distribution transformer group, the search conditions including that the low-voltage tie switch is in an open position, the low-voltage main switch of the opposite side distribution transformer is in a closed position, the three-phase voltage of the low-voltage bus of the opposite side distribution transformer meets the voltage standard, and the sum of the actual load current of the distribution transformer to be transferred and the current load current of the opposite side distribution transformer does not exceed the initial threshold of the dynamic maximum allowable current of the opposite side distribution transformer; searching for at least two direct transfer schemes for each low-voltage transfer distribution transformer to form a candidate scheme library.

[0009] Further preferably, the dynamic maximum allowable current is calculated by the following formula: ; In the formula, the dynamic maximum allowable current of the opposite side distribution transformer, the low-voltage side rated current of the opposite side distribution transformer, the temperature coefficient of the low-voltage line conductor material, the real-time temperature of the conductor, the reference temperature of the conductor, the line loss correction coefficient of the low-voltage line, the actual load current of the to-be-switched distribution transformer, the voltage sag duration of the low-voltage bus, the rated voltage of the low-voltage bus, the apparent capacity of the opposite side distribution transformer, the natural constant.

[0010] Further preferably, in S5, the priority ranking includes calculating priority coefficients and ranking the priority coefficients, the priority coefficients being calculated by the following formula: ; In the formula, is the switching scheme priority coefficient, is the electricity use priority weight of the user served by the to-be-switched distribution transformer, is the load rate of the to-be-switched distribution transformer, and , the dynamic maximum allowable current of the opposite side distribution transformer, the actual load current of the to-be-switched distribution transformer, the topological distance between the to-be-switched distribution transformer and the opposite side distribution transformer, the number of high-priority users served by the to-be-switched distribution transformer, the total number of users served by the to-be-switched distribution transformer; the direct switching switching scheme in the candidate scheme library is ranked in descending order of priority coefficients, and the scheme at the top of the ranking is selected as the target switching scheme.

[0011] Further preferably, in S5, the power flow check is calculated by the following formula: ; In the formula, is the total equivalent load current of the to-be-switched distribution transformer, is the actual load current of the nth to-be-switched distribution transformer, is the adaptive adjustment coefficient of the nth to-be-switched distribution transformer, and , is the switching delay time of the nth to-be-switched distribution transformer, is the dynamic maximum allowable current of the target switching distribution transformer; if the total equivalent load current exceeds , , , If the priority coefficient is low to high, the to-be-transformed power distribution transformer is removed until the checking condition is met.

[0012] A medium and low voltage collaborative self-healing system for global user fast power recovery is applied to the medium and low voltage collaborative self-healing method for global user fast power recovery, comprising a medium voltage self-healing interactive module, a multi-dimensional parameter acquisition module, a power distribution transformer analysis module, a low voltage transfer decision module and an execution control module; the medium voltage self-healing interactive module is used for receiving medium voltage permanent fault information and medium voltage self-healing action results, and outputting medium voltage fault information to the power distribution transformer analysis module; the multi-dimensional parameter acquisition module is electrically connected with the medium voltage self-healing interactive module, acquires low voltage side parameters, and outputs the parameters to the power distribution transformer analysis module after standardization processing; the power distribution transformer analysis module is electrically connected with the multi-dimensional parameter acquisition module, outputs a low voltage self-healing power distribution transformer set to the low voltage transfer decision module after completing power distribution transformer set analysis; the low voltage transfer decision module is electrically connected with the power distribution transformer analysis module, and outputs a transfer scheme to the execution control module after generating the transfer scheme; the execution control module is electrically connected with the low voltage transfer decision module, executes the transfer scheme, and triggers parameter reacquisition when switch failure occurs.

[0013] Further preferably, the multi-dimensional parameter acquisition module comprises a temperature acquisition unit, a power quality monitoring unit, a user information interactive unit and a topology data acquisition unit; the temperature acquisition unit acquires conductor temperature, the power quality monitoring unit acquires voltage sag duration, the user information interactive unit acquires user power consumption priority, and the topology data acquisition unit acquires topology distance; each unit is electrically connected with the power distribution transformer analysis module, synchronously transmits parameters by using a unified data transmission protocol, and ensures data real-time performance and consistency; the temperature acquisition unit supports multi-measuring point data uploading, and the power quality monitoring unit can generate a power quality analysis report.

[0014] Further preferably, the low voltage transfer decision module comprises a topology analysis unit, a scheme sorting unit and a checking unit; the topology analysis unit identifies power distribution transformer groups and outputs to the scheme sorting unit; the scheme sorting unit sorts transfer schemes by calling a priority coefficient model and outputs to the checking unit; the checking unit calculates total equivalent load current by calling a power flow checking model, removes power distribution transformers that do not meet the condition, and generates a final low voltage transfer scheme; the topology analysis unit, the scheme sorting unit and the checking unit are sequentially electrically connected, transmit data in real time through internal interfaces, and ensure that the scheme meets safety and power recovery priority requirements.

[0015] Compared with the prior art, the application has the following beneficial effects: The application realizes extension of self-healing technology to low-voltage user side, realizes medium-voltage self-healing and low-voltage self-healing cooperative linkage, can realize quick power recovery of low-voltage users of fault area voltage loss distribution transformer, solves the problem of power recovery dead zone of medium-voltage self-healing fault area, and meets the demand of global user quick self-healing power recovery. In addition, the conventional idea of existing static current limit value is broken through, dynamic parameter collection such as low-voltage side conductor real-time temperature and low-voltage bus voltage sag duration is introduced, distribution transformer set screening, transfer supply scheme searching and checking are completed in combination with medium-voltage fault information, and the parameter updating scheme is re-collected and updated when the switch remote control fails, forming a closed loop control. This technical point accurately solves the core problem that the static current limit value in the background technology is not combined with the low-voltage side dynamic parameters, leading to line overload trip after transfer supply, avoids the deviation of static limit value and actual bearing capacity in extreme environment, effectively reduces overload trip, and improves the power recovery efficiency and power supply stability of global users. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only exemplary, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0017] Fig. 1 The flow chart of the medium-low voltage cooperative self-healing method for global user quick power recovery of the present application; Fig. 2 The connection block diagram of the medium-low voltage cooperative self-healing system for global user quick power recovery of the present application; Fig. 3 The typical wiring diagram of the distribution transformer group of the present application. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0019] The concepts involved in the present application will be described below in combination with the drawings. It should be pointed out here that the following descriptions of the concepts are only to make the content of the present application easier to understand, and do not mean the limitation of the protection scope of the present application; meanwhile, the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0020] The existing low-voltage collaborative self-healing method does not integrate low-voltage conductor temperature, voltage sag duration, user power priority and other multi-dimensional parameters, the transfer scheme adopts static current limit and has no switch failure retry mechanism, which leads to overload trip during power recovery, high-priority user power recovery delay and low self-healing efficiency.

[0021] Based on this, please refer to Figs. 1-3 The embodiment provides a kind of low-voltage collaborative self-healing method for global user fast power recovery, comprising: S1: receiving medium voltage permanent fault information, fault positioning is carried out on the medium voltage side, and the fault area is remotely controlled and isolated, and the medium voltage non-fault area is remotely controlled and powered on; S2: collecting low-voltage conductor real-time temperature, low-voltage bus voltage sag duration, user power priority of distribution transformer, topology distance of standby transfer distribution transformer and target transfer distribution transformer, and actual load current of standby transfer distribution transformer, to realize dynamic bearing check of distribution transformer low-voltage transfer; S3: based on the medium voltage permanent fault information and the above-mentioned collection parameters, for the fault area, determine the loss of pressure distribution transformer set, carry out low-voltage self-healing start boundary check of loss of pressure distribution transformer, and determine the low-voltage self-healing distribution transformer set; S4: low-voltage topology analysis is carried out on the start low-voltage self-healing distribution transformer set to identify the connected distribution transformer group, and low-voltage direct transfer power supply scheme is searched in the unit of distribution transformer group; S5: priority sorting and power flow check are carried out on the direct transfer power supply scheme, and low-voltage automatic transfer of loss of pressure distribution transformer is realized by low-voltage self-healing, to restore the power supply of low-voltage user in the fault area; S6: transfer scheme is executed according to the order of distribution transformer group and the priority descending order in distribution transformer group, if switch remote control fails, the above-mentioned parameters are re-collected and low-voltage transfer scheme is updated, until global user power recovery is completed.

[0022] The method constructs a complete process around the medium and low voltage cooperative self-healing, and the core necessary technical features cover multi-parameter acquisition, distribution transformer set screening, topology analysis, scheme optimization and dynamic retry. After receiving the permanent fault information, the medium voltage side processing link determines the fault point through fault location technology, remotely controls the medium voltage switch to isolate the fault area, and remotely controls the power restoration of the medium voltage line in the non-fault area to restore the basic power supply on the medium voltage side. The multi-parameter acquisition on the low voltage side is the key premise, and the real-time temperature of the conductor, the voltage sag duration of the low voltage bus, the user power priority, the topology distance and the actual load current are collected to provide comprehensive data support for subsequent analysis. Based on the medium voltage fault information analysis, the list of non-restored distribution transformers is formed, the distribution transformers with low voltage automation terminal, available tie switch and normal communication channel are screened, the low voltage self-healing distribution transformer set is determined through pre-checking, and invalid distribution transformers are excluded. In the topology analysis link, the low voltage topology database of the distribution network is called, and the distribution transformers with direct tie path are divided into distribution transformer groups based on the connection relationship of the tie switch to ensure that the distribution transformers in the group can be transferred to each other; the direct transfer power restoration scheme is searched in units of distribution transformer groups to avoid invalid search across groups.

[0023] The scheme sorting and checking link sorts the schemes through the priority model and ensures safety through power flow calculation; the execution link executes in parallel between distribution transformer groups and in descending order of priority within the group, and if the switch remote control fails, the parameters are immediately re-collected to update the scheme, avoiding secondary failure due to outdated parameters, and forming a closed loop control.

[0024] The technical effects of the above embodiment include: realizing multi-parameter cooperative self-healing of medium and low voltage, avoiding overload and delay of high-priority users caused by static schemes, solving the problem of power restoration interruption after switch failure, and improving the power restoration efficiency and power supply reliability of the whole area.

[0025] The existing low voltage parameter acquisition has no clear equipment source and data processing standard, the acquisition process is not synchronized with the medium voltage fault processing, the parameter timeliness is poor, and the format is not compatible, which leads to low accuracy of subsequent distribution transformer set analysis and scheme generation.

[0026] Based on this, in S2, in the step of collecting low voltage side parameters, the conductor real-time temperature is obtained through a temperature sensor, the low voltage bus voltage sag duration is obtained through a power quality monitoring terminal, the user power priority is obtained from a power marketing system, the topology distance is obtained from a distribution network GIS system, and the actual load current is obtained through a low voltage automation terminal; the parameter acquisition process is started synchronously with the medium voltage side fault isolation step, the acquisition frequency is set to 1 per second to ensure the parameter timeliness; after acquisition, the parameters are standardized and converted into a numerical format recognizable by the system for subsequent distribution transformer set analysis.

[0027] The scheme clearly specifies the device source, timing control and data processing standard of parameter collection, solves the ambiguity and timeliness problem of the collection link. In terms of device source, the real-time temperature of the conductor is obtained through a distributed optical fiber temperature sensor or a wireless temperature sensor. The distributed optical fiber sensor is laid along the low-voltage line, which can realize continuous monitoring of each 500-meter measuring point with an accuracy of ±0.5°C. The wireless temperature sensor is installed at the conductor joint to avoid complex wiring. Both of them can capture the temperature change of the conductor in real time. The duration of voltage sag of the low-voltage bus is collected by a power quality monitoring terminal. The terminal integrates a voltage collection chip with a sampling rate of 10 kHz, which can accurately record the start time and end time of voltage sag, calculate the duration, and monitor voltage amplitude, frequency and other parameters to assist in judging voltage stability. The user's electricity priority is obtained from the power marketing system, which stores user profiles and labels user load levels according to industry standards. Through the power dispatching data network, the priority classification of users served by the transformer is obtained in real time. The topological distance is obtained from the distribution network GIS system, which stores spatial data such as the geographical location of the transformer and the line direction. The shortest path distance between the standby supply transformer and the target transformer is extracted through the API interface with an accuracy of ±10 meters. The actual load current is collected by a low-voltage automation terminal (such as DTU, FTU), which has a built-in current transformer with a sampling accuracy of 0.2 level and uploads the three-phase current at the low-voltage side of the transformer in real time. In terms of timing control, parameter collection and medium-voltage side fault isolation are started simultaneously. After receiving the fault information, the medium-voltage side triggers the isolation operation, and the low-voltage side starts working to avoid the problem that the parameters cannot reflect the real-time state due to collection lag. The collection frequency of once per second balances the real-time performance and device power consumption, which can capture dynamic changes such as voltage sag and current fluctuation in time, and will not increase the hardware burden due to high-frequency collection. In terms of data processing, the formats output by different devices are standardized, such as converting the analog signal (4-20mA) output by the temperature sensor into a numerical value and extracting the voltage sag duration field from the JSON format data output by the power quality monitoring terminal to ensure that the subsequent transformer set analysis module can be directly called and avoid data loss or incorrect analysis due to format incompatibility.

[0028] The technical effects of the above embodiments include: clearly specifying the device, timing and processing standard of parameter collection, ensuring reliable parameter source, strong real-time performance and format compatibility, providing high-quality data for transformer set analysis and scheme generation, and improving the accuracy of subsequent links.

[0029] The existing transformer set determination has no clear screening logic and pre-checking link, which may include transformers without transfer supply conditions or with safety risks in the analysis, resulting in redundant self-healing process, low efficiency and safety hazards.

[0030] Based on this, the step of determining the set of distribution transformers includes: analyzing the list of distribution transformers without power restoration contained in the medium voltage fault information, extracting the distribution transformer number, the distribution transformer to which it belongs, and the load type information, forming the set of distribution transformers without voltage; selecting the distribution transformers with low voltage automation terminal, available low voltage tie switch and normal communication channel from the set of distribution transformers without voltage, excluding the distribution transformers without low voltage transfer condition, forming the set of low voltage self-healing distribution transformers; pre-checking each low voltage self-healing distribution transformer, the pre-checking content including whether the distribution transformer is in the locked state, whether the low voltage main switch is in the closed position, whether the low voltage main switch has fault signal, and whether the dynamic load capacity of the distribution transformer meets the basic load requirement, and the distribution transformer meeting all pre-checking conditions is included in the set of low voltage self-healing distribution transformers.

[0031] The scheme determines the flow of the set of distribution transformers through three-level screening logic, the core of which is to gradually exclude distribution transformers without transfer condition and risk, ensuring the effectiveness of subsequent analysis objects. In the set of distribution transformers without voltage, the list of distribution transformers without power restoration is contained in the medium voltage fault information, and the distribution transformer number, the distribution transformer to which it belongs, and the load type are extracted when analyzing the list, forming the set of distribution transformers without voltage, and clearly defining the initial analysis range. In the set of low voltage self-healing distribution transformers, the focus is on the basic conditions for transfer. The low voltage automation terminal is the core hardware, which needs to have data acquisition and remote control functions, and without the terminal, remote operation cannot be realized. The available low voltage tie switch needs to be in the open position and have no mechanical failure or electrical failure, and the closing capacity is normal, which is the physical channel for transfer. The normal communication channel ensures the transmission of instructions and data feedback between the terminal and the master station, and communication interruption cannot be controlled. If any of the three is missing, it is determined that there is no transfer condition, and it is directly excluded from the set of distribution transformers without voltage, greatly reducing the subsequent analysis range. In the pre-checking link of the set of low voltage self-healing distribution transformers, safety and feasibility are considered. The distribution transformer locking state needs to be unlocked, and the locking state prohibits operation to avoid misoperation. The low voltage main switch needs to be in the closed position to ensure that the fault distribution transformer can be isolated by opening operation to prevent fault propagation. The low voltage main switch has no fault signal to ensure that the switch can operate normally. The dynamic load capacity of the distribution transformer needs to meet the basic load requirement to avoid overload before transfer. Only when all four conditions are met can the distribution transformer be included in the set of low voltage self-healing distribution transformers, ensuring that each distribution transformer has the prerequisite for safe self-healing.

[0032] The technical effects of the above embodiments include: through three-level screening and pre-checking, distribution transformers without transfer condition and with safety risk are excluded, invalid analysis processes are reduced, the accuracy of the set of distribution transformers is improved, and a reliable foundation is laid for subsequent self-healing scheme generation.

[0033] The existing transfer scheme does not search for distribution transformer group identification, the search range has no boundary, and the number of alternative schemes is insufficient, which easily causes problems such as the scheme not meeting the topological condition or no alternative options after a single scheme fails, affecting the reliability of power restoration.

[0034] Based on this, the step of searching for a low-voltage direct transfer power supply scheme includes: calling a low-voltage topology database of a distribution network, obtaining low-voltage tie switch connection relationships, conductor types and power supply radius information of all distribution transformers in a starting self-healing distribution transformer set; based on the tie switch connection relationships, dividing distribution transformers with direct low-voltage tie paths into the same distribution transformer group; searching for a direct transfer power supply scheme in each distribution transformer group, and the search conditions include that the low-voltage tie switch is in an open position, a low-voltage main switch of a side distribution transformer is in a closed position, three-phase voltages of a low-voltage bus of the side distribution transformer meet a voltage standard, and a sum of actual load currents of the to-be-transferred distribution transformer and a current of the side distribution transformer does not exceed an initial threshold of a dynamic maximum allowable current of the side distribution transformer; searching for at least two direct transfer power supply schemes for each to-be-transferred distribution transformer to form an alternative scheme library.

[0035] The scheme defines a search range through distribution transformer group identification, clearly defines scheme search conditions and alternative quantities, and improves the rationality and reliability of the transfer scheme. The topology data calling link is the foundation, and the low-voltage topology database of the distribution network stores core topology information of all distribution transformers in the starting self-healing distribution transformer set. The low-voltage tie switch connection relationship records whether the distribution transformers are directly connected through the tie switch, which is the key to distribution transformer group identification. The conductor type determines the temperature coefficient and current-carrying capacity of the conductor, providing a basis for subsequent dynamic current calculation. The power supply radius is used to determine whether the transfer path exceeds a reasonable range to avoid excessive line loss leading to a decrease in power supply quality. The distribution transformer group identification link is based on the tie switch connection relationship, and uses a connectivity analysis algorithm to divide distribution transformers with direct low-voltage tie paths into the same distribution transformer group. For example, distribution transformers A and B have a tie, distribution transformers B and C have a tie, and distribution transformers A, B and C belong to the same distribution transformer group. The distribution transformers in the same distribution transformer group have physical transfer conditions, and the cross-group distribution transformers do not have direct ties and do not need to be searched, which greatly reduces the search range and improves efficiency. The scheme search conditions ensure the feasibility and safety of the scheme. The low-voltage tie switch is in an open position to enable transfer through closing. If it is in a closed position, a new transfer path cannot be established. The low-voltage main switch of the side distribution transformer is in a closed position to ensure that the side distribution transformer has restored low-voltage power supply and can provide power for the to-be-transferred distribution transformer. The three-phase voltages of the low-voltage bus of the side distribution transformer meet the voltage standard to ensure that the power supply quality meets the standard after transfer. The sum of the currents of the to-be-transferred and side distribution transformers does not exceed the initial threshold of the dynamic maximum allowable current of the side distribution transformer to initially avoid overload. The alternative scheme library construction link requires at least two direct transfer power supply schemes for each to-be-transferred distribution transformer to form an alternative library to prevent a single scheme from failing due to switch failure, load fluctuation and other problems, and to avoid the interruption of power restoration due to the lack of alternative schemes.

[0036] The technical effects of the above embodiments include: reducing the search range through distribution transformer group identification, ensuring the feasibility of the scheme through clear conditions, avoiding single failure risks through multiple alternative schemes, and improving the search efficiency and power restoration reliability of the transfer scheme.

[0037] The existing transfer current limit uses the static rated current of the distribution transformer, without considering dynamic parameters such as conductor temperature and voltage sag, resulting in a limit that does not match the actual carrying capacity of the line, and easily causing overload tripping after transfer.

[0038] Based on this, the dynamic maximum allowable current is calculated by the following formula: ; In the formula, is the dynamic maximum allowable current of the opposite distribution transformer, is the low-voltage side rated current of the opposite distribution transformer, is the temperature coefficient of the conductor material of the low-voltage line, is the real-time temperature of the conductor, is the reference temperature of the conductor, is the line loss correction coefficient of the low-voltage line, is the actual load current of the distribution transformer to be transferred, is the voltage sag duration of the low-voltage bus, is the rated voltage of the low-voltage bus, is the apparent capacity of the opposite distribution transformer, is a natural constant.

[0039] This scheme builds a dynamic current limit model through an original formula, integrating multiple parameters such as temperature, voltage sag, and load, ensuring that the limit matches the actual carrying capacity of the line, and the definition, dimension, and logical correlation of each parameter in the formula are clear. is the core output, in amperes (A), reflecting the maximum current that the low-voltage side of the opposite distribution transformer can carry in real time, and is the key basis for checking the transfer scheme. is the low-voltage side rated current of the opposite distribution transformer, in A, from the distribution transformer nameplate, and is the basic reference value for dynamic limits. is the temperature coefficient of the conductor material, in 1 / ℃ (resistance change rate per degree Celsius), copper conductor is 0.003931 / ℃, and aluminum conductor is 0.004291 / ℃, used to correct the impact of temperature on conductor resistance - as temperature rises, resistance increases, and current-carrying capacity decreases, so the term in the formula decreases as increases, reducing . is the reference temperature of the conductor, in ℃, defaulting to 25℃, which is the reference temperature corresponding to the rated resistance of the conductor, ensuring uniformity in temperature correction. is the line loss correction coefficient, dimensionless, positively related to the cross-sectional area of the conductor, such as 120mm² conductor is 0.85, and 70mm² conductor is 0.92, used to correct the line loss differences of different conductors; is the actual load current of the distribution transformer to be transferred, in A, reflecting the size of the load to be transferred; is the duration of voltage sag in low-voltage bus, in seconds (s), which is the duration of voltage below 198 V, affecting line loss and switch reliability; is the rated voltage of low-voltage bus, in volts (V), which is 220 V by default; is the apparent capacity of the opposite transformer, in kilovolt-ampere (kVA), reflecting the overall capacity of the transformer; The item modifies the influence of line loss and voltage sag on carrying capacity, or When it increases, this item decreases, further reducing . is a natural constant (about 2.718), The item is an additional correction of voltage sag on switch reliability, When it is extended, the switch action reliability is reduced, and it needs to be further reduced to reserve a safety margin to ensure that even if the switch action is delayed, the line will not be overloaded.

[0040] The technical effects of the above embodiments include: dynamically adjusting the current limit value, solving the problem that the static rated current does not match the actual carrying capacity, avoiding overload trip caused by temperature rise and voltage sag after transfer, and improving the safety of transfer.

[0041] The existing transfer scheme priority is only sorted by single dimension of transformer load rate, without considering user electricity priority, topology distance and other factors, resulting in delay of power restoration of high-priority users, which does not meet the power supply principle of "important load priority recovery".

[0042] Therefore, the priority coefficient is calculated by the following formula: ; In the formula, is the transfer scheme priority coefficient, is the electricity priority weight of the users served by the transformer to be transferred, is the load rate of the transformer to be transferred, and , is the dynamic maximum allowable current of the opposite transformer, is the actual load current of the transformer to be transferred, is the topology distance between the transformer to be transferred and the opposite transformer, is the number of high-priority users served by the transformer to be transferred, is the total number of users served by the transformer to be transferred; the direct transfer transfer scheme in the candidate scheme library is sorted in descending order of priority coefficient, and the scheme with the highest priority is selected as the target transfer scheme.

[0043] The scheme realizes reasonable sorting of the transfer scheme through the priority formula of multi-factor coupling, and the core is to balance the user importance, load safety and transfer efficiency. The definition, dimension and logical association of each parameter in the formula are clear. It is a priority coefficient, dimensionless, with a value range of 0-1.2, and the larger the value, the higher the priority of the scheme, which is the direct basis for sorting. It is a user electricity priority weight, dimensionless, set according to load level - first-level load, hospital, emergency command center =1.0, second-level load, commercial center, important industry =0.7, third-level load, ordinary residents =0.3, directly reflects the importance of users, and ensures that high-priority users have priority. It is the load rate of the transfer supply distribution transformer, dimensionless, calculated from (the actual load current of the transfer supply distribution transformer, unit A) and (the rated current of the transfer supply distribution transformer, unit A), It reflects the remaining load capacity of the transfer supply distribution transformer, and the stronger the remaining capacity, the larger the value, and the higher the priority of the scheme, avoiding selecting a load-full distribution transformer for transfer. It is the dynamic maximum allowable current of the opposite side distribution transformer (unit A), It is the actual load current of the transfer supply distribution transformer (unit A), Dimensionless, the larger the ratio, the more sufficient the capacity of the opposite side distribution transformer to carry the load of the transfer supply, and the square term strengthens the influence of this factor, ensuring the selection of a safe scheme. It is the topological distance between the transfer supply distribution transformer and the opposite side distribution transformer, unit: kilometer (km), Dimensionless, the closer the distance, the larger the value, and the higher the priority of the scheme, reducing the transfer line loss and power restoration time, the farther the distance, the larger the line loss, and the longer the power restoration time. It is the number of high-priority users carried by the transfer supply distribution transformer (unit: households), It is the total number of users carried by the transfer supply distribution transformer (unit: households), It is the proportion of high-priority users, dimensionless, and 0.08 is the weight coefficient of this factor, further strengthening the priority of the scheme with a high-priority user concentrated distribution transformer, avoiding missing the group demand due to a single weight. When calculating, first determine the values of each parameter, and then substitute them into the formula to get Sort the schemes in the candidate scheme library in descending order of The first scheme is the target transfer scheme, ensuring that the sorting logic fits the actual power supply demand.

[0044] ​The technical effects of the above embodiments include: realizing multi-dimensional priority sorting of transfer schemes, ensuring that schemes with high priority, sufficient load and short distance are preferentially executed, solving the problem of delay in power restoration of high-priority users, and improving the quality of power supply services.

[0045] In the existing multi-to-one mode, the power flow check only directly sums the actual load currents of the to-be-transferred distribution transformers, without considering the load fluctuation caused by transfer delay, which may easily cause the total equivalent load to exceed the dynamic limit value of the opposite distribution transformer, resulting in overload.

[0046] Therefore, in the multi-to-one mode, the power flow check is calculated by the following formula: ; In the formula, is the total equivalent load current of the to-be-transferred distribution transformer, is the actual load current of the nth to-be-transferred distribution transformer, is the adaptive adjustment coefficient of the nth to-be-transferred distribution transformer, and is the transfer delay time of the nth to-be-transferred distribution transformer, is the dynamic maximum allowable current of the target distribution transformer; if the total equivalent load current exceeds , the to-be-transferred distribution transformers are excluded in priority order from low to high until the check condition is met.

[0047] The scheme realizes accurate verification of the load in the multi-to-one mode by introducing a check formula with an adaptive adjustment coefficient. The core is to correct the load fluctuation caused by transfer delay. The definitions, dimensions, and check logic of the parameters in the formula are clear. is the total equivalent load current of the nth to-be-transferred distribution transformer, unit: ampere (A), which is the core calculation value of the check and reflects the actual equivalent load that the target distribution transformer needs to bear after transfer. is the actual load current of the nth to-be-transferred distribution transformer, unit: A, which is collected by the low-voltage automation terminal and is the basic data for load calculation. is the adaptive adjustment coefficient of the nth to-be-transferred distribution transformer, which is dimensionless and is used to correct the load change caused by transfer delay. During the transfer delay period, the load of the to-be-transferred distribution transformer may fluctuate due to user electricity consumption behavior (such as motor starting and equipment switching). The longer the delay, the higher the risk of fluctuation, so is calculated by is the transfer delay time of the nth to-be-transferred distribution transformer, unit: second (s), which is the time from the issuance of the transfer instruction to the closing of the tie-in switch. ​​​​​​​​​​The longer, The smaller, the corresponding equivalent load is reduced, and the fluctuation safety margin is reserved; It is a natural constant (about 2.718), 0.05 is the delay influence coefficient, which is determined through a large number of experiments, and ensures that the correction amplitude conforms to the actual load fluctuation rule. It is the dynamic maximum allowable current of the target transfer distribution transformer, unit A, which is the maximum current that the target distribution transformer can bear in real time, and provides a safety threshold for the checking process. In terms of checking process, first, the The standby transfer distribution transformer With , calculate the of each; then calculate the of each, and sum up to get the total equivalent load current; compare the total equivalent load current with If the total equivalent load current is less than or equal to , the scheme meets the safety requirements; if the total equivalent load current is greater than , according to (priority coefficient) from low to high, the standby transfer distribution transformer is removed, and the total equivalent load current is recalculated every time a standby transfer distribution transformer is removed, until the total equivalent load current is less than or equal to , to ensure that the target distribution transformer will not be overloaded after transfer.

[0048] The technical effects of the above embodiment include: accurately checking the total equivalent load in the multi-transfer-one mode, correcting the load fluctuation caused by transfer delay, avoiding the total load exceeding the dynamic limit value, solving the overload problem caused by traditional direct summation, and improving the transfer safety.

[0049] The medium and low voltage cooperative self-healing system module is missing, the interaction between the modules is unclear, and the multi-parameter cooperative self-healing cannot be realized, resulting in low system power recovery efficiency and poor reliability.

[0050] Therefore, the medium and low voltage cooperative self-healing system module is missing, the interaction between the modules is unclear, and the multi-parameter cooperative self-healing cannot be realized, resulting in low system power recovery efficiency and poor reliability.

[0051] The system builds a complete hardware architecture of medium and low voltage collaborative self-healing by clarifying the functions and electrical connection relationship of the five core modules, and realizes closed-loop control of data acquisition, analysis, decision-making, and execution. The medium voltage self-healing interaction module is the interface module of the system and the medium voltage side, which integrates a communication interface on the hardware, and is used to receive permanent fault information and medium voltage self-healing action results sent by the medium voltage protection device and the measurement and control device. The module analyzes and filters the received information, extracts the medium voltage fault information related to low voltage self-healing, and transmits it to the distribution transformer analysis module through an electrical connection line, to provide basic data of the medium voltage side for low voltage distribution transformer set analysis and avoid blind analysis of the low voltage side. The multi-dimensional parameter acquisition module is the data source of the low voltage side, which is electrically connected with the medium voltage self-healing interaction module, integrates a sensor interface, a system interface, and a data processing unit on the hardware, obtains user power consumption priority and topological distance through the system interface, and transmits the standardized data to the distribution transformer analysis module through an electrical connection, to provide comprehensive and compatible low voltage parameters for subsequent analysis. The distribution transformer analysis module is the core of distribution transformer set screening, which is electrically connected with the multi-dimensional parameter acquisition module and integrates a processor and a memory on the hardware. After receiving the medium voltage fault information and low voltage parameters, the module executes the logic of loss of voltage distribution transformer set analysis, self-healing distribution transformer set screening, and start-up of self-healing distribution transformer set pre-checking, generates a start-up self-healing distribution transformer set, and transmits it to the low voltage transfer decision-making module through an electrical connection to exclude invalid distribution transformers. The low voltage transfer decision-making module is the core of scheme generation, which is electrically connected with the distribution transformer analysis module and integrates a high-performance processor on the hardware. After receiving the start-up self-healing distribution transformer set, the module executes the logic of topological analysis, transfer scheme search, scheme priority sorting, and power flow checking, generates a final transfer scheme, and transmits it to the execution control module through an electrical connection to ensure the safety and priority of the scheme. The execution control module is the core of scheme execution and dynamic adjustment, which is electrically connected with the low voltage transfer decision-making module and integrates a remote control unit and a feedback unit on the hardware. After receiving the transfer scheme, the module sends a remote control instruction to control the action of the low voltage tie switch and the main switch, and receives the feedback signal of the switch action at the same time. If the feedback switch fails, the module triggers the multi-dimensional parameter acquisition module to re-acquire parameters through an electrical connection, drives the low voltage transfer decision-making module to update the scheme, realizes closed-loop control, and avoids interruption during power restoration.

[0052] The technical effects of the above embodiments include building a complete medium and low voltage collaborative self-healing hardware architecture, clarifying the functions and interactions of the modules, realizing multi-parameter collaboration and dynamic adjustment, solving the problem of low power restoration efficiency caused by module absence and unclear interactions, and improving the reliability of the system.

[0053] The existing multi-dimensional parameter acquisition module does not have a subdivision function unit, and the parameter acquisition device and data transmission protocol are not clear, which leads to incomplete parameter acquisition, asynchronous data transmission, and affects the accuracy of subsequent module analysis.

[0054] Based on this, the multi-dimensional parameter acquisition module includes a temperature acquisition unit, an electric energy quality monitoring unit, a user information interaction unit, and a topology data acquisition unit; the temperature acquisition unit acquires conductor temperature, the electric energy quality monitoring unit acquires voltage sag duration, the user information interaction unit acquires user electricity priority, and the topology data acquisition unit acquires topology distance; each unit is electrically connected with the distribution transformer analysis module, adopts a unified data transmission protocol to synchronously transmit parameters, and ensures data real-time performance and consistency; the temperature acquisition unit supports multi-measuring-point data uploading, and the electric energy quality monitoring unit can generate an electric energy quality analysis report.

[0055] The module is subdivided into four functional units, the collection content of each unit, transmission standard and additional function are clear, and the parameter collection is comprehensive and the transmission is reliable. The temperature collection unit is the source of conductor temperature data, and a distributed optical fiber temperature sensor or a wireless temperature sensor is used on the hardware. The distributed optical fiber sensor is laid along the low-voltage line throughout the whole process, and the continuous temperature monitoring of each 500-meter measuring point is realized through the optical time domain reflection technology. The measurement range is-50~150℃, the accuracy is ±0.5℃, the multi-measuring-point data parallel upload is supported, the temperature change of different sections of the line can be fully captured, the wireless temperature sensor adopts ZigBee or LoRa protocol, and is installed at key positions such as conductor joints and branches to avoid complex wiring. Both of them process and collect signals through a signal conditioning circuit to ensure the accuracy of temperature data. The unit transmits temperature data to the distribution transformer analysis module through electrical connection to provide temperature parameters for dynamic current calculation. The power quality monitoring unit is the source of voltage sag data, and integrates voltage collection chips and data processing chips on the hardware. The three-phase voltage of the low-voltage bus can be collected in real time, the voltage amplitude is used to judge and record the start time and end time of the sag, the duration is calculated, and parameters such as voltage effective value, frequency and harmonic content are monitored. The unit can generate a power quality analysis report, and transmits the sag duration and the analysis report to the distribution transformer analysis module through electrical connection to provide a basis for switch reliability evaluation and dynamic current correction. The user information interaction unit is the source of user priority data, and integrates an Ethernet interface or a 4G module on the hardware. The power dispatching data network is connected with the power marketing system to obtain the load level (first / second / third), user name and power consumption address of the users connected to the distribution transformer, to ensure that the priority data is consistent with the marketing system and to avoid manual input errors. The unit transmits the user power consumption priority to the distribution transformer analysis module through electrical connection to provide user importance parameters for distribution transformer set screening and scheme sorting. The topology data acquisition unit is the source of topology distance data, and integrates a standard API interface on the hardware. The geographic position coordinates of the to-be-supplied distribution transformer and the target distribution transformer are extracted from the distribution network GIS system, the shortest path distance between the two is calculated through a distance calculation formula, and the accuracy is ±10 meters. The unit transmits the topology distance to the distribution transformer analysis module through electrical connection to provide distance parameters for distribution transformer set identification and scheme sorting. Each unit is electrically connected with the distribution transformer analysis module, a unified IEC61850-9-2 data transmission protocol is used, the data transmission delay is less than 1 second, the time stamps of all parameters are unified, the data is not out of sync due to different protocols or time stamp differences, and the accuracy of subsequent analysis is ensured.

[0056] The technical effects of the above embodiments include subdividing the parameter collection unit, clearly defining the function and transmission standard of each unit, realizing comprehensive parameter collection and synchronous transmission, solving the problems of incomplete collection and asynchronous data, and providing high-quality data support for subsequent modules.

[0057] The existing low-voltage transfer decision module has no subdivision function unit, the topology analysis, scheme sorting and power flow checking logic are fuzzy, and the data transmission between modules has no clear interface, resulting in low efficiency and poor accuracy of the transfer scheme generation, which cannot meet the safety and priority requirements.

[0058] Therefore, the low-voltage transfer decision module includes a topology analysis unit, a scheme sorting unit and a checking unit. The topology analysis unit identifies the transformer group and outputs to the scheme sorting unit. The scheme sorting unit sorts the transfer scheme by calling the priority coefficient model and outputs to the checking unit. The checking unit calculates the total equivalent load current by calling the power flow checking model, eliminates the transformers that do not meet the conditions, and generates the final transfer scheme. The topology analysis unit, the scheme sorting unit and the checking unit are electrically connected in sequence, and data is transmitted in real time through internal interfaces to ensure that the scheme meets the safety and power restoration priority requirements.

[0059] The module subdivides three major functional units, clearly defines the logic and data transmission relationship of each unit, and realizes efficient and accurate generation of the transfer scheme. The core is to complete the topology definition, scheme optimization and safety verification in steps. The topology analysis unit is the core of transformer group identification. The processor and topology database are integrated on the hardware, and the connectivity analysis algorithm based on depth-first search is built-in. After receiving the start self-healing transformer set transmitted by the transformer analysis module, the unit loads the connection relationship of the tie switch in the low-voltage topology database of the distribution network, such as transformer A-tie switch 1-transformer B. Through the algorithm, all tie paths of the transformer are traversed, and the transformers with direct tie paths are divided into the same transformer group, for example, transformers A and B have a tie, and B and C have a tie. Then A, B and C are classified into a group. At the same time, the available tie switches and conductor types of each transformer in the group are marked to form the transformer group information. The unit transmits the transformer group information to the scheme sorting unit in real time through the internal high-speed electrical interface to define the range for scheme search. The scheme sorting unit is the core of scheme optimization. The FPGA chip is integrated on the hardware, and the priority coefficient calculation model is built-in. After receiving the transformer group information, the unit searches for the direct transfer power scheme that meets the conditions for each transformer to be transferred in the group, forming an alternative scheme library. At the same time, the user power priority ( ), topology distance ( ), actual load current ( ), dynamic maximum allowable current of the opposite transformer ( ) are obtained from the multi-dimensional parameter acquisition module, and the (priority coefficient) of each alternative scheme is calculated. The alternative schemes are sorted in descending order according to to form a sorted scheme list (including scheme details, The unit transmits the sorting scheme list to the verification unit in real time through an internal interface, ensuring that high-priority schemes enter the verification process first. The verification unit is the core of scheme security verification, integrating a high-performance processor (such as Intel Xeon) and a built-in power flow verification model. After receiving the sorting scheme list, this unit extracts the actual load current of each transformer to be transferred for the "multiple-to-one" mode scheme. ) and transfer delay time ( (Based on historical data from the execution control module), calculate the adaptive adjustment coefficient for each unit ( ) and total equivalent load current ( ); Obtain the dynamic maximum allowable current of the target power supply transformer ( ), compare the total equivalent load current with If the total equivalent load current is ≤ If the total equivalent load current is greater than 100%, then the solution meets the safety requirements and is determined as the final power transfer solution; if the total equivalent load current is greater than 100%, then the solution meets the safety requirements and is determined as the final power transfer solution. Then sort the list according to the sorting scheme. The system eliminates power transfer transformers from low to high load, recalculating the total equivalent load current for each removed transformer until safety requirements are met. Simultaneously, a verification report is generated, and the final power transfer scheme and report are transmitted to the execution control module via an internal interface. The three units are electrically connected sequentially, using a high-speed serial bus for data transmission at a rate ≥100Mbps. This ensures a seamless scheme generation process, with the total time from topology analysis to final scheme output being <5 seconds, and each step prioritizing power restoration. ) and safety ( ), to avoid neglecting one aspect for another.

[0060] The technical effects of the above embodiments include: subdividing the power transfer decision-making units, clarifying the logic and data transmission of each unit, realizing efficient sorting and security verification of the solutions, solving the problems of low efficiency and poor accuracy in solution generation, and ensuring that the solutions meet the requirements of security and power restoration priority.

[0061] The embodiments and / or implementation methods described above are merely preferred embodiments and / or implementation methods for implementing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any way. Any person skilled in the art can make some modifications or alterations to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as the technology or embodiments that are substantially the same as the present invention.

[0062] The principles and implementation manners of the present application are described herein by using specific examples, and the above example descriptions are only used to help understand the method of the present application and its core idea. The above descriptions are only preferred embodiments of the present application, and it should be pointed out that, due to the limited nature of the language expression, there are objectively infinite specific structures, and for ordinary skilled persons in the technical field, some improvements, refinements or changes can be made without departing from the principles of the present application, and the above technical features can also be combined in an appropriate manner; these improvements, refinements, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, shall be regarded as the protection scope of the present application.

Claims

1. A method for medium and low voltage collaborative self-healing for fast power restoration for global users, characterized in that, The method comprises the following steps: S1, receiving medium voltage permanent fault information, performing fault positioning on the medium voltage side, remotely controlling the isolation of the fault area, and remotely controlling the power restoration of the non-fault area on the medium voltage side; S2, collecting the real-time temperature of the low-voltage conductor, the voltage sag duration of the low-voltage bus, the user power priority of the distribution transformer, the topology distance between the standby distribution transformer and the target distribution transformer, and the actual load current of the standby distribution transformer, and realizing dynamic load checking of the low-voltage power supply of the distribution transformer; S3, based on the medium voltage permanent fault information and the above-mentioned collected parameters, for the fault area, determining the set of voltage loss distribution transformers, performing low-voltage self-healing start boundary checking of the voltage loss distribution transformers, and determining the set of low-voltage self-healing distribution transformers; S4, performing low-voltage topology analysis on the set of low-voltage self-healing distribution transformers to identify the connected distribution transformer groups, searching for low-voltage direct transfer power supply schemes in units of distribution transformer groups; S5, performing priority sorting and power flow checking on the direct transfer power supply scheme, and realizing low-voltage automatic transfer of the voltage loss distribution transformers through low-voltage self-healing to restore the power supply of the low-voltage users in the distribution transformers in the fault area; S6, executing the transfer scheme according to the order of the distribution transformer groups and the priority descending order of the distribution transformer groups, if the switch remote control fails, re-collecting the above-mentioned parameters and updating the low-voltage transfer scheme until the power supply of all users is restored.

2. The method of claim 1, wherein the method further comprises: S2 specifically includes: the real-time temperature of the conductor is obtained by a temperature sensor, the voltage sag duration of the low-voltage bus is obtained by a power quality monitoring terminal, the user power priority is obtained from a power marketing system, the topology distance is obtained from a distribution network GIS system, and the actual load current is obtained by a low-voltage automation terminal; the parameter collection process is started synchronously with the fault isolation step on the medium voltage side, and the collection frequency is set to 1 per second to ensure the timeliness of the parameters; after collection, the parameters are standardized and converted into a numerical format that can be recognized by the system for subsequent distribution transformer set analysis.

3. The method of claim 2, wherein the method further comprises: S3 specifically includes: analyzing the list of non-restored distribution transformers contained in the medium voltage fault information, extracting the distribution transformer number, the distribution transformer it belongs to, and the load type information to form the set of voltage loss distribution transformers; selecting distribution transformers with low-voltage automation terminals, available low-voltage tie switches, and normal communication channels from the set of voltage loss distribution transformers, excluding distribution transformers without low-voltage transfer conditions to form the set of low-voltage self-healing distribution transformers; pre-checking each low-voltage self-healing distribution transformer, which includes whether the distribution transformer is in a locked state, whether the low-voltage main switch is in a closed position, whether there is a fault signal in the low-voltage main switch, and whether the dynamic load capacity of the distribution transformer meets the basic load requirement, and all pre-checked distribution transformers are included in the set of low-voltage self-healing distribution transformers.

4. The method of claim 3, wherein the method further comprises: In S4, the step of searching for a low-voltage direct transfer power supply scheme includes: calling a low-voltage topology database of network distribution, obtaining connection relationship of low-voltage tie switches, wire type and power supply radius information of all distribution transformers in the starting self-healing distribution transformer set; based on the connection relationship of the tie switches, the distribution transformers with direct low-voltage tie paths are divided into the same distribution transformer group; searching for a direct transfer power supply scheme in each distribution transformer group, and the search conditions include that the low-voltage tie switch is in the open position, the low-voltage main switch of the opposite side distribution transformer is in the closed position, the three-phase voltage of the low-voltage bus of the opposite side distribution transformer meets the voltage standard, and the sum of the actual load current of the to-be-converted distribution transformer and the current load current of the opposite side distribution transformer is less than the initial threshold of the dynamic maximum allowable current of the opposite side distribution transformer; at least two direct transfer power supply schemes are searched for each low-voltage to-be-converted distribution transformer, and a candidate scheme library is formed.

5. The method of claim 4, wherein, The dynamic maximum allowable current is calculated by the following formula: ； In the formula, is the dynamic maximum allowable current of the opposite transformer, is the low-voltage side rated current of the opposite transformer, is the temperature coefficient of the low-voltage line conductor material, is the real-time temperature of the conductor, is the reference temperature of the conductor, is the line loss correction coefficient of the low-voltage line, is the actual load current of the transformer to be switched, is the duration of the low-voltage bus voltage sag, is the rated voltage of the low-voltage bus, is the apparent capacity of the opposite transformer, is the natural constant.

6. The method of claim 1, wherein the method further comprises: In S5, the priority sorting includes calculating a priority coefficient, and sorting the priority coefficient, the priority coefficient is calculated by the following formula: ； In the formula, is the priority coefficient of the transfer solution, is the power consumption priority weight of the users of the to-be-transferred power supply and distribution transformer, is the load rate of the to-be-transferred power supply and distribution transformer, and , is the dynamic maximum allowable current of the opposite power supply and distribution transformer, is the actual load current of the to-be-transferred power supply and distribution transformer, is the topological distance between the to-be-transferred power supply and distribution transformer and the opposite power supply and distribution transformer, is the number of high-priority users of the to-be-transferred power supply and distribution transformer, is the total number of users of the to-be-transferred power supply and distribution transformer; the direct transfer solution in the candidate solution library is sorted according to the priority coefficient from large to small, and the solution at the top of the sorting is selected as the target transfer solution.

7. The method of claim 6, wherein the method further comprises: In S5, the power flow check is calculated by the following formula: ； In the formula, is the total equivalent load current of the standby power supply and distribution transformer, is the first the actual load current of the standby power supply and distribution transformer, is the first the adaptive adjustment coefficient of the standby power supply and distribution transformer, and , is the first the transfer delay time of the standby power supply and distribution transformer, is the dynamic maximum allowable current of the target power supply and distribution transformer; if the total equivalent load current exceeds , the standby power supply and distribution transformer is removed according to the priority coefficient from low to high until the check condition is met.

8. A medium and low voltage collaborative self-healing system for global user fast power restoration, applied to the medium and low voltage collaborative self-healing method for global user fast power restoration according to any one of claims 1-7, characterized in that, The medium-voltage self-healing interaction module is used for receiving medium-voltage permanent fault information and medium-voltage self-healing action results, and outputting medium-voltage fault information to the distribution transformer analysis module; the multi-dimensional parameter acquisition module is electrically connected with the medium-voltage self-healing interaction module, acquires low-voltage side parameters, and outputs the low-voltage side parameters to the distribution transformer analysis module after standardized processing; the distribution transformer analysis module is electrically connected with the multi-dimensional parameter acquisition module, outputs a starting low-voltage self-healing distribution transformer set to the low-voltage transfer decision module after completing distribution transformer set analysis; the low-voltage transfer decision module is electrically connected with the distribution transformer analysis module, outputs a transfer scheme to the execution control module after generating the transfer scheme; and the execution control module is electrically connected with the low-voltage transfer decision module, executes the transfer scheme and triggers parameter reacquisition when switch failure occurs.

9. The medium and low voltage collaborative self-healing system for fast power recovery of global users according to claim 8, characterized in that, The multi-dimensional parameter acquisition module includes a temperature acquisition unit, a power quality monitoring unit, a user information interaction unit and a topology data acquisition unit; the temperature acquisition unit acquires wire temperature, the power quality monitoring unit acquires voltage sag duration, the user information interaction unit acquires user power consumption priority, and the topology data acquisition unit acquires topology distance; each unit is electrically connected with the distribution transformer analysis module, adopts a unified data transmission protocol to synchronously transmit parameters, and ensures data real-time performance and consistency; the temperature acquisition unit supports multi-measurement-point data uploading, and the power quality monitoring unit can generate a power quality analysis report.

10. The medium and low voltage collaborative self-healing system for fast power recovery of global users according to claim 9, characterized in that, The low-voltage transfer decision module includes a topology analysis unit, a scheme sorting unit and a checking unit; the topology analysis unit identifies distribution transformer groups and outputs the distribution transformer groups to the scheme sorting unit; the scheme sorting unit sorts the transfer scheme by calling a priority coefficient model and outputs the transfer scheme to the checking unit; the checking unit calculates total equivalent load current by calling a power flow checking model, eliminates distribution transformers that do not meet the conditions, and generates a final transfer scheme; the topology analysis unit, the scheme sorting unit and the checking unit are sequentially electrically connected, transmit data in real time through internal interfaces, and ensure that the scheme meets safety and power restoration priority requirements.

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