A method for fast fault isolation of protection and measurement and control integration of box-type substation

Abstract

The application discloses a kind of box-type substation protection and integrated fault rapid isolation method of measurement and control, specifically relates to distribution network fault isolation technical field, for solving the problem that existing box-type substation is not complete in protection action information, there is disturbance in measurement and when primary wiring relationship is complex, it is difficult to determine fault section in time accurately, isolation range is large and important user supply is insufficient, and fault disposal process lacks traceable evidence chain.Proceeding with the division of section in box-type substation according to primary switch and cable joint, establishing unified time section level topology model and fault evidence fingerprint bound with protection configuration, scoring operation slice based on section fault assumption and theoretical event mode, and obtaining minimum isolation switch set under isolation constraint, so that in the case of incomplete protection action, measurement disturbance and complex wiring, fault section can still be locked and isolation scheme considering user supply and electrical safety boundary can be generated, to improve fault isolation correctness and rapidity.

Description

Technical Field

[0001] This invention relates to the field of power distribution network fault isolation technology, specifically to a rapid fault isolation method integrating protection and measurement and control in a prefabricated substation. Background Technology

[0002] In existing technologies, urban power distribution networks widely adopt the prefabricated substation form, which centrally arranges high-voltage incoming lines, distribution transformers, and low-voltage feeders in a limited space. Fault detection and handling are jointly completed by local protection devices, monitoring and control devices, and upper-level dispatching and distribution automation systems. Common practices often rely on the overcurrent, instantaneous trip, and grounding settings of individual devices such as incoming line protection, feeder protection, and transformer protection. The fault is determined by "which line trips to determine which line is faulty" and "the fault range is roughly determined by the current magnitude and switch position," supplemented by a few fixed operation tickets or preset interconnection schemes for sectionalizing switches and tie switches to achieve basic fault isolation and partial load transfer. Although some distribution automation systems have introduced feeder automation, fault indicator information, and simple topology analysis, they are mostly based on logical inferences at the line or bay level, mainly based on protection actions and switch states. There is a lack of unified modeling for the fine connection relationships between incoming line sections, busbar sections, transformer sections, and multiple feeder sections within the prefabricated substation, and there is also a lack of collaborative analysis of multi-source measurements between field devices under unified time synchronization conditions.

[0003] In actual operation, the fault modes of prefabricated substations are complex. They may include single-feeder short circuits, as well as overlapping conditions such as grounding, imbalance, and voltage drops. Protection actions are also affected by factors such as setting compromises, switch failures, maloperation, reclosing, and the activation of backup power, rendering simple rules like "whoever trips is the faulty line" unreliable. Under current technology, prefabricated substations typically lack a section-level topology model that corresponds one-to-one with primary wiring and protection configurations. Current, voltage, and protection status data collected during faults are mostly referenced to the local clocks of individual devices, lacking a unified time synchronization support for operational slices. Measurement anomalies and communication jitter also lack systematic organization and version management, making fault location judgment based on protection and measurement information susceptible to amplified single-point errors. For fault isolation, existing technologies are mostly based on experience or fixed logic, cutting off sections of incoming lines, busbars, and feeders in sequence, or relying on pre-configured typical operation tickets. It is difficult to formally constrain conditions such as "faulty sections and non-faulty sections must be electrically isolated, important users must be given priority in power supply, and isolated power islands must not be formed" under complex interconnection structures and important user distribution. Furthermore, there is a lack of mechanisms to automatically converge to the switch combination with the smallest possible power outage range under these constraints.

[0004] Furthermore, existing protection and control devices in prefabricated substations focus more on the tripping action itself in engineering practice. They often lack a unified version locking and recording method for the topology view, measurement and processing rules, judgment logic, and actual switching operations used when a fault occurs. Relevant information is scattered across protection action records, remote signaling change records, and maintenance logs, making it difficult to form a complete and reproducible chain of evidence for fault handling. This not only creates difficulties for post-incident analysis and responsibility determination but also makes it difficult for higher-level dispatching and distribution automation systems to clearly grasp the safety boundaries and compliance levels when integrating local automatic isolation capabilities.

[0005] In summary, the current technology faces the following key technical challenges in the integrated protection and control scenario of prefabricated substations: Under conditions of incomplete protection action information, measurement disturbances, and relatively complex primary wiring relationships, existing technologies lack a systematic mechanism that uses sections as the granularity, under unified time synchronization and clear topology constraints, to reliably identify the faulty section and formally generate a fault isolation scheme that controls the power outage range while ensuring the supply of important users. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a rapid fault isolation method integrating protection and measurement and control in prefabricated substations, thereby solving the problems mentioned in the background section.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a rapid fault isolation method integrating protection and measurement and control in a prefabricated substation, comprising: S1. Divide the substation into sections based on primary switches and cable joints, establish a section-level topology model and configure unified time synchronization. S2. When any section protection device outputs at least one start flag or action flag, collect the protection status, measurement value and switch status of each section within the fault time window, align them according to the time synchronization to form an operation slice, and identify them as fault evidence fingerprints according to the section. S3. Propose fault hypotheses for each section, derive theoretical event modes based on the section-level topology model and protection configuration, compare the theoretical event modes with fault evidence fingerprints, calculate scores, and determine the set of fault sections based on the score results and topology continuity constraints. S4. Based on the set of fault sections, select controllable switches around the fault sections according to the topology model, construct isolation constraints, and solve to obtain the minimum set of isolation switches that satisfy the constraints. S5. Generate a fault isolation operation sequence based on the minimum set of disconnecting switches and the current switch status. After each step is hypothetically executed, update the segment-level topology model and check that the faulty segment is isolated while the power supply to the non-faulty segment is maintained. S6. Control the switch to complete the opening and closing operations according to the fault isolation operation sequence, record the changes in fault current and the recovery status of section voltage, and write the fault section set, the minimum disconnecting switch set and the execution result into the fault handling record.

[0008] Furthermore, S1 includes: Based on the wiring diagram and on-site survey results, the sections are divided with the high-voltage incoming switch, the high-voltage side switch of the transformer, the bus section switch, the low-voltage feeder switch and the cable joint as the electrical boundaries. Each section is identified, and its voltage level, connection relationship, and protection function are registered to form a section-level topology model in the protection and control device. The protection and control device is set as a unified timing node. The time reference is obtained from an external time source and the timing deviation is recorded. When the timing deviation exceeds the timing deviation threshold, the fault section identification step that depends on the time sequence is stopped, and the tripping action is performed according to the existing short circuit protection setting.

[0009] Furthermore, S2 includes: When the protection and control device outputs at least one start flag or action flag in any section of the protection device, the fault time window is determined according to the unified time synchronization. Within the fault time window, the section protection status, current value, voltage value and primary switch status are collected and timestamped. After alignment, the operation slices are divided. Before forming the running slice, the collected values ​​are processed according to the pre-configured sorting rules and the current and voltage values ​​are classified into amplitude level ranges; Within the running slice, the above quantities are aggregated according to the segment identifier to form a fault evidence fingerprint with a version number and written to the fault event record area.

[0010] Furthermore, S3 includes: For each segment in the segment-level topology model, the protection and control device proposes segment fault hypotheses based on the target operation slice after the fault time window ends; Under the premise that this section is assumed to be a fault section, a theoretical event mode is constructed that includes protection start-up status, protection operation status, current level, voltage level and related primary switch status. The theoretical event patterns are compared item by item with the fault evidence fingerprints in the target running slice, and a scoring record containing segment identifiers and scoring levels is generated according to the pre-configured scoring rules.

[0011] Furthermore, the protection and control device sorts the scoring records of all sections according to the scoring level, sets a scoring threshold, removes sections with scores below the scoring threshold, and selects sections with scores above the scoring threshold as candidate fault sections. Topological continuity constraints are applied between candidate fault segments, and the combination of candidate fault segments is determined as a set of fault segments only when the candidate fault segments form a continuous conductive path in the segment-level topology model.

[0012] Furthermore, S4 includes: After obtaining the set of fault sections, the protection and control device selects primary switches that are directly connected to the set of fault sections and connected through adjacent non-fault sections not exceeding the preset maximum number of jumps, based on the section-level topology model, to form a set of controllable switches. Construct isolation constraints to limit the number of controllable switches in the open state on each electrical connection path between faulty and non-faulty sections, keep sections marked as important users on the power supply side, prevent the formation of isolated power supply islands, and ensure that existing protection direction configurations and switch operation procedures are not violated. Under isolation constraints, the combination of controllable switch open and closed states is searched, and the combination with the minimum number of required open switches is selected as the minimum isolation switch set.

[0013] Furthermore, when a backup power supply is available, the protection and control device identifies the interconnecting switches and switching switches associated with the backup power supply from the set of controllable switches; Based on the allowable capacity range of the backup power supply, the upper limit of the load of the non-faulty section powered by the backup power supply is determined. Under the condition that the capacity constraint and the isolation constraint are satisfied at the same time, the combination of controllable switch opening and closing states is searched step by step. The combination with the fewest number of tripped switches under the premise of maintaining power supply to the non-faulty section is selected as the minimum isolation switch set under the participation of the backup power supply.

[0014] Furthermore, S5 includes: After determining the minimum set of disconnecting switches, the protection and control device reads the closing and opening positions, local and remote selection status, and interlocking signals of the controllable switches. The target state and prerequisite conditions of each switch in the fault isolation operation sequence are determined based on the segment-level topology model and the minimum set of disconnecting switches. When the preconditions are met, a fault isolation operation sequence is hypothetically executed within the segment-level topology model, and the switch status and power supply path are updated. After confirming that the faulty segment is in an electrically isolated state and the non-faulty segment is in a power supply state, the fault isolation operation sequence is written into the fault event record area.

[0015] Furthermore, S6 includes: After the fault isolation operation sequence is locked, the protection and control device uses the fault isolation operation sequence as the sole basis for action to gradually perform remote opening and closing operations on the controllable switch. Before each step is executed, if the local / remote selection status of the target switch and the interlocking signal are in an allowed combination state, a control command with a unique sequence number is sent, and the completion status of the step is marked according to the switch position feedback. If the waiting time limit is exceeded and the retransmission reaches the upper limit, the control is marked as incomplete and subsequent automatic isolation is stopped. In the fault handling record, the evidence chain identifier is generated by associating the segment-level topology model version, fault evidence fingerprint version, scoring rule version, and isolation constraint rule version, and is then called by the superior system.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. By dividing the prefabricated substation into sections based on primary switches and cable joints, a section-level topology model with unified time synchronization is established. During the fault process, a fault evidence fingerprint bound to the topology and protection configuration is constructed. The target operating slice is scored according to the section fault assumption and theoretical event mode. Under isolation constraints, the minimum disconnecting switch set is solved. Thus, even under field conditions such as incomplete protection actions, measurement disturbances, and relatively complex primary wiring relationships, the fault section carrying the fault source can still be accurately located, and a fault isolation scheme that takes into account both the power supply protection of important users and the electrical safety boundary can be automatically generated. This improves the correctness, speed, and operational reliability of fault isolation in prefabricated substations under the premise of controlled power outage range.

[0017] 2. After determining the minimum set of disconnecting switches, a fault isolation operation sequence with preconditions is generated by combining local and remote selection states and interlocking signals. Hypothetical execution and connectivity verification are performed step-by-step on the segment-level topology model. During actual execution, operation sequence control, waiting and retransmission mechanisms, monitoring of fault current and voltage recovery processes under unified timing, and fault handling records and evidence chain identifiers locked to model versions, fault evidence fingerprint versions, scoring rule versions, and isolation constraint rule versions are introduced. This ensures that automatic fault isolation actions remain idempotent, orderly, and traceable even under fluctuating communication environments and adjusted operating modes. It facilitates secure access and post-event verification for the dispatch master station and maintenance system, improving the engineering applicability and safety compliance of the integrated protection and control device for prefabricated substations. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating a rapid fault isolation method integrating protection and measurement and control in a prefabricated substation according to the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example: Figure 1 A flowchart illustrating a rapid fault isolation method integrating protection and measurement / control in a prefabricated substation according to the present invention is provided. The method includes: S1. Within the prefabricated substation, sections are divided according to primary switches and cable joints. A section-level topology model is established and a unified time synchronization is configured. The specific implementation is as follows: In a prefabricated substation serving the city's power distribution network, the internal structure of the prefabricated substation and its directly connected incoming and outgoing lines are systematically reviewed based on the substation's planning and design documents and as-built primary wiring diagram, combined with the results of on-site surveys.

[0021] In this manual, urban power distribution network refers to a power supply network that supplies power to urban users via medium-voltage power distribution lines and consists of power distribution lines, power distribution transformers, and related switching equipment; a prefabricated substation refers to a complete set of equipment that centrally installs high-voltage switching equipment, power distribution transformers, and low-voltage power distribution devices in an enclosed metal enclosure, suitable for use in roads, residential areas, and industrial and commercial parks.

[0022] During on-site identification, the high-voltage incoming line switch refers to the switchgear located at the entrance of the medium-voltage feeder to the transformer substation, used to connect or disconnect the power supply from the upstream power grid. The transformer high-voltage side switch refers to the switchgear connected between the transformer high-voltage winding and the high-voltage busbar or incoming line, used to protect and operate the high-voltage side of the transformer. The busbar sectionalizing switch refers to the switchgear that divides the busbar into multiple operating sections on the high-voltage or low-voltage busbar, used to achieve sectional operation or interconnected operation. The low-voltage feeder switch refers to the switchgear that supplies power from the low-voltage side of the transformer or the low-voltage busbar to each low-voltage outgoing line. The cable joint refers to the connection point between the busbar or switch terminal and the external cable conductor.

[0023] Using the aforementioned primary switches and cable joints as electrical boundaries, a segment is formed between each pair of adjacent boundaries. In this specification, a segment refers to an electrical unit that is relatively consistent in voltage level and operating function, consisting of the conductive parts between two adjacent natural boundaries. For example, a conductive path from the outlet end of the high-voltage incoming switch to the bus connection point, a connection from the high-voltage side terminal of the transformer to the high-voltage bus, a connection from the low-voltage side terminal of the transformer to a certain low-voltage feeder switch, and a cable segment between a certain feeder switch and the corresponding cable joint.

[0024] Each incoming line, each busbar section, each high- and low-voltage side connection section of a transformer, and each feeder is divided into sections. Each section is assigned a unique section identifier, and the voltage level of the section, the type and rated parameters of the connected primary switch, the ratio and accuracy class of the configured current transformer and voltage transformer, the type of protection function installed, and the connection relationship with other sections are recorded. The above information is entered into the protection and control device installed in the transformer substation.

[0025] In this specification, the protection and control device refers to an intelligent electronic device that centrally realizes protection, measurement, and remote control functions and has logic operation and storage capabilities. During the data entry process, the device uses sections as basic units and the electrical connections between sections as boundaries to form a section-level topology model. The physical meaning of the section-level topology model is a network description constructed with sections as nodes and conductive connections between sections as edges, which is used to support subsequent fault section identification and fault isolation scheme calculation. Among them, the upstream section refers to the section located on the power supply side in the normal power supply direction, and the downstream section refers to the section located on the load side in the normal power supply direction. The power supply direction is determined based on the direction from the power source to the load and is recorded in the section-level topology model as a unidirectional connection relationship.

[0026] The segment-level topology model is preferably entered by technical personnel with expertise in primary systems and relay protection, based on the primary wiring diagram and on-site verification results. The segment connection relationships are verified through manual checking or trial operation. After verification, a model version number is assigned. The model and version number are preferably stored in the non-volatile storage medium of the protection and control device, and are retained even after the device is powered off. When the segment division or connection relationship needs to be modified due to primary system upgrades or the addition of equipment, a new version can be generated based on the original model. The new version is modified and re-verified, and the old version is set to read-only, thus forming a clear historical version chain, so that subsequent analysis of a certain fault can trace back to the topology view used at that time.

[0027] To ensure that the temporal sequence of relevant quantities in each section can be compared horizontally, the protection and control device is set as the unified time synchronization node of this transformer. In this manual, the unified time synchronization node refers to the functional module that obtains time information through an external time source or a superior system and provides a consistent time reference to all measurement circuits and status acquisition circuits inside the device. The time reference is a reference clock used to mark the time when various current, voltage values ​​and switch states occur.

[0028] The unified time synchronization node preferably obtains time information from the dispatch automation system or the superior substation through the dedicated time synchronization channel of the power system. Alternatively, it can obtain time from satellite signals by installing a satellite time synchronization module. When time information cannot be obtained through the power time synchronization channel, satellite time synchronization can be set as an alternative.

[0029] A unified timing node calibrates the internal clock of the device at a preset cycle. For each time synchronization process, the timing deviation between the local clock and the reference time is recorded. The timing deviation is stored in milliseconds. A timing deviation threshold is set to characterize the range within which the time reference can be considered reliable. The timing deviation threshold can be set to a fraction of the typical short-circuit protection action time limit. For example, when the time setting corresponding to the short-circuit protection setting is in the range of tens to hundreds of milliseconds, the timing deviation threshold is preferably set to a fraction of milliseconds to ensure that within the fault time window used in this method, the time deviation will not affect the judgment of the protection start-up sequence and measurement change trend.

[0030] When a time synchronization deviation exceeding the threshold is detected during continuous time synchronization, or when unified time synchronization is interrupted for an extended period, the device will prominently mark the version relationship between the current segment-level topology model and the time reference in its internal configuration. This will prompt maintenance personnel via the human-machine interface that the unified time may be unreliable, and restrict the subsequent time-sequence-based fault segment identification logic from participating in the current fault handling. Preferably, tripping will only be performed according to existing traditional protection settings such as overcurrent and instantaneous tripping, without adding any additional control actions to the primary system. This ensures that the system continues to operate safely in the conventional manner even when time conditions are not met. In this specification, "clear primary wiring relationship" means that the prefabricated substation has a primary wiring diagram confirmed upon completion and acceptance, the field equipment numbers are consistent with the drawings, segment boundaries can be identified through equipment nameplates and cable routing, and there are no undefined segments or suspended connection records in the segment-level topology model. "Reliable time synchronization conditions" means that the unified time synchronization node can stably control the time synchronization deviation within the time synchronization deviation threshold within the set period.

[0031] In a city prefabricated substation with a rated voltage of 10,000 kV and a single busbar segmented connection, it can form an incoming line section, a busbar section, a transformer section, and several feeder sections. The total number of sections can be set to about ten. The unified time synchronization node synchronizes with the dispatch automation system through a synchronous Ethernet channel. When the above conditions are met, the section division and section-level topology modeling capabilities provided in this step can be implemented on-site in this type of prefabricated substation. Those skilled in the art can arrange specific implementation accordingly.

[0032] S2. When any section protection device outputs at least one start flag or action flag, the protection status, measured values, and switch status of each section are collected within the fault time window, aligned according to the time synchronization to form an operating slice, and identified by section as a fault evidence fingerprint. The specific implementation is as follows: When a protection device configured in any section detects that the current value, voltage value, or derived quantity calculated from three-phase current and three-phase voltage of that section reaches a preset fault discrimination threshold and generates a start-up flag or an action flag, the protection and control device regards this operation as a fault process that needs to be analyzed in detail. Here, the derived quantity refers to zero-sequence quantity, negative-sequence quantity, and other quantities used to characterize unbalanced and ground faults. The fault discrimination threshold refers to the combination of thresholds used to distinguish between normal operation fluctuations and fault states. It is determined by the short-circuit current calculation results, the allowable voltage drop range, and the operating procedures. Preferably, it is set by technical personnel with a relay protection background in combination with the system operation mode. The start-up flag is the status flag output when the protection element detects that the quantity value has reached the action criterion. The action flag is the status flag output when the protection element actually issues a trip or block command.

[0033] When the above conditions are met, the protection and control device, taking the moment when the start-up or action flag first appears as the center, continuously reads the protection status, three-phase current RMS value, three-phase voltage RMS value, and the closing / opening status corresponding to each primary switch within a pre-set fault time window, based on the time reference provided by the unified time synchronization node. The fault time window refers to a time range extending forward and backward by several power frequency cycles around the fault trigger moment, used to cover the steady state before the fault, the fault occurrence process, and the new steady state after the protection action. The length of the time window can be set to span several power frequency cycles, preferably longer than the short-circuit protection action time limit. The duration is several times longer to ensure complete recording of the entire fault process; the protection and control device periodically reads the above values ​​according to the preset acquisition rhythm within the fault time window. The acquisition rhythm refers to the fixed time interval between two consecutive readings, which can be set to a fraction of the power frequency cycle, corresponding to several discrete sampling points within each power frequency cycle, so that the effective values ​​of the three-phase current and the effective values ​​of the three-phase voltage have sufficient density on the time axis. The switch closing and opening status forms a state mark with limited values ​​through the switch auxiliary contacts or intelligent terminals. During each acquisition and recording, the protection and control device uses the time reference provided by the unified time synchronization node as a reference and adds a timestamp to each record.

[0034] After completing the above data collection, the protection and control device performs time alignment on all records within the fault time window based on the timestamp, divides the time window into a series of equally spaced discrete moments, and regards the combination of all section protection status, measurement values ​​and switch status corresponding to each discrete moment as an operation snapshot, called an operation slice. An operation slice is a horizontal description of the electrical behavior of each section in the entire prefabricated substation at a specific moment under unified time synchronization conditions.

[0035] To avoid individual measurement anomalies from adversely affecting subsequent judgments, the protection and control device processes the collected values ​​according to pre-configured processing rules before forming the operation slice. Isolated values ​​that significantly exceed the transformer range and differ significantly from previous and subsequent samples are eliminated or replaced. Single sampling gaps caused by communication interruptions or sampling omissions are filled in. The filling method can be set to use the measured values ​​of the same measuring point at adjacent times or to estimate according to the change trend of the section within the fault time window. The processing rules are bound to the current section-level topology model version for subsequent traceability. At the same time, the protection and control device classifies the current and voltage values ​​into several non-overlapping amplitude level intervals according to the preset amplitude division method. Each interval corresponds to a numerical range, and the measurement error range and interval division version are recorded.

[0036] After completing the above processing, the protection and control device aggregates the protection start-up status, protection action status, voltage level range, current level range, and primary switch position related to the section in each operating slice according to the section identifier. This set of status variables and level information is encoded in a pre-agreed field order to form a comprehensive feature record of the section on the operating slice, which is called the fault evidence fingerprint of the section at that moment. The fault evidence fingerprint is a summary description of the electrical characteristics and protection behavior of a section at a specific moment during a fault under unified timing conditions. The protection and control device assigns a version number to the composition rules, amplitude level range division method, and sorting rules of the fault evidence fingerprint, and establishes a correspondence between the version number and the section-level topology model version, which is called the fault evidence fingerprint version.

[0037] Considering that multiple operating slices will be generated within the fault time window, the protection and control device will statistically analyze the distribution of protection start-up flags and action flags in each section of all operating slices after the fault time window ends. Based on the statistical results, one or more operating slices with the number of protection actions reaching or near the peak value will be selected as target operating slices. The target operating slice refers to the operating slice that can reflect the most obvious fault characteristics and the most concentrated protection behavior, which will be used for subsequent execution of section fault assumptions and scoring. The protection and control device will summarize the fault evidence fingerprints of all sections in the target operating slice according to the section identifier, and store them together with the current fault event number, fault time window identifier, unified time reference information, section-level topology model version number and fault evidence fingerprint version number in the fault event record area reserved inside the device. The fault event record area is a storage area used to store the key measurement information and judgment basis of each fault process for a long time. It is preferably a non-volatile storage medium that will not be lost after the device is powered off.

[0038] In a city prefabricated substation with a rated voltage of 10,000 kV, using a single busbar segmented connection and reliable unified time synchronization, for example, when a short-circuit fault occurs on a low-voltage feeder, the overcurrent protection of the feeder section starts and operates within a short time. The protection and control device can set the fault time window to cover several power frequency cycles before and after the fault, and set the acquisition rhythm to divide each power frequency cycle into several equally spaced sampling times. The effective values ​​of three-phase current, effective values ​​of three-phase voltage, and switch status of all sections within the time window are collected, and operating slices and fault evidence fingerprints are constructed according to the above method. Finally, several operating slices with the most concentrated protection actions are found within the fault time window as target operating slices. The corresponding fault evidence fingerprints are collected in the fault event record area and stored in association with the fault event number and version information. This provides a complete and traceable field observation basis for subsequent fault section hypothesis deduction and scoring based on fault evidence fingerprints. Those skilled in the art can implement this step in the field of a prefabricated substation that meets the aforementioned segment division and unified time synchronization conditions.

[0039] S3. For each section, propose fault hypotheses, derive theoretical event modes based on the section-level topology model and protection configuration, compare the theoretical event modes with fault evidence fingerprints, calculate scores, and determine the set of faulty sections based on the score results and topology continuity constraints. The specific implementation is as follows: After the fault time window ends and the target operating slice has been determined according to the aforementioned rules, the protection and control device, under the current segment-level topology model version, sequentially performs a tentative judgment on the fault situation for each segment registered in the model. Specifically, for a certain segment, the device internally proposes a segment fault hypothesis. The segment fault hypothesis is the term used in this specification to refer to the assumed situation that "a permanent short circuit or ground fault exists within this segment during this fault process, while the remaining segments remain in a non-fault state." A permanent short circuit refers to a fault in which a low-impedance path is formed between the conductors of the segment within the fault time window and disappears on its own without relying on switching operations. A ground fault refers to a fault in which an abnormal conductive path is formed between the conductors of the segment and the ground.

[0040] Under the premise that a certain section is assumed to be a fault section, the protection and control device, in combination with the upstream and downstream section connection relationships recorded in the section-level topology model, the protection types and their setting ranges configured in each section, and the power supply direction information, derives the combination of behaviors that each section should exhibit under this assumption at the time corresponding to the target operating slice. This combination is referred to as the theoretical event mode in this specification.

[0041] The theoretical event mode refers to the expected judgment results made on the protection start-up status, protection operation status, current level, voltage level, and related primary switch status of each segment at that moment when a certain segment is assumed to be a fault segment, based on the propagation law of current and voltage along the network and the protection setting principle. For example, for a segment located upstream of the fault segment, the theoretical event mode may judge that its current level should be higher than the normal operating level and the overcurrent protection in the corresponding direction should be started but not operated temporarily due to the selective requirement of the upper level. For a segment located downstream of the fault segment and whose load has been disconnected, the theoretical event mode may judge that its current level is close to zero, the voltage level is significantly reduced, and the downstream switch remains in the open state.

[0042] After proposing segment fault assumptions and deriving corresponding theoretical event modes for each segment in the segment-level topology model, the protection and control device compares the theoretical event modes with the fault evidence fingerprints obtained through the aforementioned steps within the same target operating slice item by item. The so-called item-by-item comparison means comparing, in a pre-agreed order of fields, whether the protection start-up state is consistent with the expectation, whether the protection action state is consistent with the expectation, whether the current level falls within the level indicated by the theoretical event mode, whether the voltage level conforms to the range of the theoretical event mode, and whether the relevant primary switch state matches the position specified in the theoretical event mode.

[0043] In order to convert the comparison results into sortable quantities, the protection and control device assigns weights to each comparison result according to the pre-configured scoring rules and accumulates them to form a score under the fault assumption of that section. The score indicates, in this specification, the degree of conformity between the assumption and the actual fault evidence fingerprint on the target operating slice when a certain section is assumed to be a fault section. The weights are used to reflect the importance of different observations in determining the fault location. For example, the protection action state and the protection start-up state can be assigned a weight higher than the current level and voltage level.

[0044] The scoring rules are configured by those skilled in the art before the system is put into operation. These rules include the weighting of various comparison items, the scoring level, and the deduction method for obvious inconsistencies. After configuration, the protection and control device assigns a version number to the scoring rules, which is archived along with the section-level topology model version and the fault evidence fingerprint version, so that the judgment criteria used at the time can be determined during subsequent queries. For each section fault hypothesis, the protection and control device obtains a scoring record corresponding to that hypothesis after scoring all comparison items. The scoring record includes at least the section identifier, the scoring level, and the version number of the scoring rules used.

[0045] In order to select the set of sections that best matches the current fault from among multiple fault assumptions, the protection and control device, after scoring all fault assumptions, sorts the scores of each section according to the scoring level. Preferably, a set of scoring thresholds can be set. Sections with scores below the threshold are considered unlikely to be fault sources in the current fault and are eliminated, while sections with scores above the threshold are considered candidate fault sections.

[0046] Based on this, in order to avoid the selected set of segments not matching the actual fault characteristics in terms of physical connectivity, the protection and control device checks the connection relationship between candidate segments according to the segment-level topology model. The checking rules are referred to as topology continuity constraints in this specification. Topology continuity constraints mean that the set of candidate fault segments should meet the requirement of forming a continuous conductive path or a combination of several adjacent segments in the segment-level topology model. It is not allowed to select physically isolated segments as the same fault source. Under the premise of a single fault, it is preferable to limit the length of the set of fault segments to no more than the preset maximum number of segments, thereby ensuring that the spatial distribution of the set of fault segments conforms to the primary system structure.

[0047] Protection and control devices can be configured with a balance rule between rating level ranking and topological continuity constraints. For example, the candidate set can be expanded to upstream and downstream adjacent segments first around the segment with the highest rating, and the fault segment set can only be included if the adjacent segment also has a high rating.

[0048] In a city prefabricated substation with a rated voltage of 10,000 kV and a single busbar segmented connection, for example, when a phase-to-phase short circuit occurs within a certain low-voltage feeder section, the fault evidence fingerprint corresponding to the target operating slice within the fault time window is usually manifested as follows: the current level of the feeder section reaches the highest preset level, the voltage level drops to the lowest level, and the overcurrent protection of the feeder switch has been activated and operates within a short time. Meanwhile, the current level of the upstream incoming line section connected to the feeder increases significantly, the incoming direction protection is activated but has not yet operated, the busbar segmented section maintains a near-normal current and voltage level and the protection is not activated, and the current and voltage levels of other non-faulty feeder sections are close to normal.

[0049] After the protection and control device proposes section fault assumptions for all sections in sequence and calculates the scores according to the aforementioned scoring rules, it can usually obtain the result that the score level of the faulty feeder section under its section fault assumption is significantly higher than that of other sections. However, when proposing section fault assumptions for incoming line sections or busbar sections, there will be significant inconsistencies between the theoretical event mode and the actual fault evidence fingerprint in multiple indicators such as protection operation status and voltage level, resulting in the score level being lower than the scoring threshold, and thus being eliminated from the candidate set.

[0050] Under the premise of satisfying the topological continuity constraint, the protection and control device will form a fault section set for this fault by selecting the sections with higher scores and which are continuous in the section-level topology model. The fault section set is the name given in this specification to the group of sections consisting of one or more adjacent sections that are identified by this method as carrying the source of this fault.

[0051] Finally, the protection and control device writes the set of fault sections, the scoring level of each section, and the version number of the scoring rule used, together with the fault event number, the section-level topology model version number, and the fault evidence fingerprint version number, into the fault event record area. This combination is regarded as the section fault identification result of this fault. The section fault identification result provides the basis for subsequent construction of isolation constraints and calculation of the minimum disconnect switch set. Those skilled in the art can implement this step in the field of a box-type substation that meets the aforementioned conditions of section division, unified time synchronization, and fault evidence fingerprint construction, based on the above rules.

[0052] S4. Based on the set of fault sections, select controllable switches around the fault sections according to the topology model, construct isolation constraints, and solve for the minimum set of isolation switches that satisfy the constraints. The specific implementation is as follows: After obtaining the set of faulty sections from the aforementioned section fault identification results, the protection and control device, under the current section-level topology model version, first identifies the range of operable switches surrounding the set of faulty sections. Specifically, the device reads the primary switch information in the section-level topology model that is directly connected to the set of faulty sections or connected through a few adjacent non-faulty sections. These few adjacent non-faulty sections can be set as adjacent sections not exceeding a preset maximum number of trips. The maximum number of trips is determined by those skilled in the art based on the primary system scale and control range, and is used to limit the search range of the controllable switch set without changing the isolation constraints themselves. Switches with remote operability and within the control authority of this device are selected from the aforementioned primary switches to form the controllable switch set in this specification. A controllable switch refers to a switching device that can be opened or closed by the protection and control device issuing control commands during the execution of this method, such as a transformer high-voltage incoming line switch, a busbar sectionalizing switch, a low-voltage feeder switch, and a ring network switch connected to the transformer via communication.

[0053] During the identification process, switches that only have local manual operation capabilities but lack remote control are recorded only as part of the topological connectivity and are not included in the controllable switch set. To balance power supply reliability and electrical safety during fault isolation, the protection and control device internally constructs a set of rules to constrain the combinations of open and closed states of controllable switches. This set of rules is referred to as isolation constraints in this specification. Isolation constraints refer to several conditions that must be met simultaneously when determining a fault isolation scheme, including at least the following: On each electrical connection path between the faulty section and the non-faulty section, there is at least one controllable switch in the open state to cut off the conductive path between the faulty section and the non-faulty section; Sections marked as important users in the operation and management system are preferentially retained on the power supply side. Important user sections refer to those carrying hospitals, communication hubs, etc. For sections with high requirements for power supply continuity, such as transportation hubs, maintenance personnel should mark them with a flag field in the section-level topology model; controllable switch combinations should not form small conductive networks containing only power sources and a very small number of loads or not monitored by this device, to avoid forming isolated power islands. In this manual, an isolated power island refers to a local power grid structure consisting of power sources and a small number of loads that is not included in the complete monitoring and protection link coverage of this device; the proposed opening and closing states of controllable switches should not violate existing protection direction configurations and switch operation procedures. For example, it is not allowed to allow a specific switch to undertake the main protection disconnection task when the protection direction is significantly opposite to the actual current flow direction.

[0054] The aforementioned isolation constraints are configured and adjusted by technical personnel with system operation experience before the device is put into use. The protection and control device records the specific content of the isolation constraints as constraint rules and assigns a version number to the constraint rules. The version number, along with the section-level topology model version number and the section fault identification result, are archived together to confirm the basis of the isolation logic at that time during subsequent analysis and tracing.

[0055] After the isolation constraints are determined, the protection and control device constructs a switch state combination space with the open / closed state of each switch in the controllable switch set as variables. In the combination space, each group of open / closed states is checked according to the conditions recorded in the isolation constraint rule version. The switch open / closed combination that simultaneously satisfies the following conditions is that all connecting paths between the fault section and the non-fault section are cut off by at least one open controllable switch, the important user section is still on the power supply side, no isolated power island is formed, and the existing protection direction configuration and operating procedures are not violated is taken as the feasible combination. In the feasible combination set, the protection and control device takes the number of switches that need to perform the opening action as the optimization objective, and determines the combination with the minimum number of opening actions as the minimum isolation switch set in this specification. The minimum isolation switch set refers to the set of switches that minimizes the number of controllable switches participating in fault isolation under the premise of satisfying all isolation constraints.

[0056] For scenarios with backup power supplies, this method preferably adds rules for the use of backup power supplies to the isolation constraints. Backup power supplies refer to power paths that are in standby mode during normal operation and can supply power to some non-faulty sections by closing tie switches when the main power supply fails. In this case, the protection and control device can adopt a step-by-step strategy during the combination search: First, identify tie switches and switching switches related to backup power supplies in the set of controllable switches. Search for controllable switch opening and closing combinations within the allowable capacity range of backup power supplies to maintain power supply to more non-faulty sections by activating backup power supplies. The allowable capacity range of backup power supplies can be determined based on the difference between the rated capacity of backup power supplies and the load already undertaken. During the combination search, the total load of sections supplied by backup power supplies is limited to not exceeding this range. Among the combinations that pass the above isolation constraint checks, select one or a few candidate combinations with the goal of minimizing the number of required trip switches as the minimum set of isolation switches with backup power supplies involved.

[0057] To facilitate subsequent execution and recording, the protection and control device will write the identifier, expected opening and closing status, and version number of the isolation constraint rule used in this operation for each controllable switch in the final determined minimum disconnecting switch set, along with the scoring information in the fault section set and section fault identification results, into the fault event record area as the basic data for generating the fault isolation operation sequence.

[0058] In a city-type prefabricated substation with a rated voltage of 10,000 kV, a single busbar sectionalized connection, and a small number of remotely controlled ring network switches, for example, when the fault section set only includes a certain low-voltage feeder section, the controllable switch set typically includes the feeder switch, the busbar sectionalizing switch connected to the busbar section where the feeder is located, and the upstream high-voltage incoming switch. Under normal circumstances where the backup power supply is not activated, the protection and control devices will obtain multiple combinations that satisfy the isolation constraints during the combination search process. Among them, the combination that only opens the faulty feeder switch while keeping the busbar sectionalizing switch and the high-voltage incoming switch stationary requires the fewest opening actions and is therefore determined as the minimum disconnecting switch set. Under alternative operating conditions with backup power supply available, For example, when power can be fed back to some non-faulty feeders through ring network interconnection, the protection and control device can first search for switch opening and closing combinations that still meet the isolation constraints under the premise that the total load of the section powered by the backup power supply does not exceed the allowable capacity of the backup power supply when the specific ring network switch is closed and the backup power supply is put into use. Then, the switch combination that can maintain power supply to more non-faulty sections and achieve electrical isolation between the faulty section and the non-faulty section with fewer tripping operations is selected as the minimum disconnecting switch set. Those skilled in the art can implement all the functions of this method in fault isolation scheme generation in the field of box-type substation that meets the above conditions of section-level topology model construction, unified time synchronization and section fault identification.

[0059] S5. Generate a fault isolation operation sequence based on the minimum set of disconnecting switches and the current switch states. After each hypothetical execution step, update the segment-level topology model and check that the faulty segment is isolated while the power supply to the non-faulty segment is maintained. The specific implementation is as follows: After the minimum set of disconnecting switches is determined, the protection and control device, under the current section-level topology model version, in order to transform the static switch combination into an action sequence that can be safely executed on site, first reads the actual closing and opening position, local / remote selection status, and interlocking signals associated with each switch in the controllable switch set. The local / remote selection status refers to the status flag in the on-site switch operation circuit used to indicate whether the switch is currently only allowed to be operated locally or remotely. It is usually determined by the selection switch position and feedback contacts on the switch body or the local control box. The interlocking signal refers to the status signal that reflects whether the electrical interlocking and mechanical interlocking conditions are met, and is used to prevent the false issuance of the disconnection command when the bus voltage, current, or disconnecting switch position does not meet the safety conditions.

[0060] After obtaining the above status information, the protection and control device, in conjunction with the expected open / closed state of each switch in the minimum disconnecting switch set during this fault handling, and relying on the connection relationships of each section, the location of the power supply line, and the load distribution recorded in the section-level topology model, constructs the fault isolation operation sequence corresponding to this fault. The fault isolation operation sequence is the name given in this manual to a set of sequential switch operation steps. Each step in the sequence specifies the target open / closed state of a certain controllable switch and is accompanied by a set of conditions that need to be met before performing the step. These conditions are referred to as preconditions in this manual. The preconditions include at least the following safety constraints: the local / remote selection state of the switch is set to allow remote control; the interlocking signal associated with the switch is in an action-allowed state; the related switches at the upper or lower levels are in the specified open / closed positions; and the voltage associated with the bus or line where the switch is located drops to a safe value range.

[0061] To verify that the operation sequence would not cause the faulty section to reconnect or experience a large-scale power outage during execution, the protection and control device internally simulated the planned fault isolation operation sequence step by step. Simulated execution, without issuing control commands to the actual equipment on site, simulated the effect of each operation on the segment-level topology model and operating status information. Specifically, before executing a certain operation, it checked whether the preconditions for that step were met. If they were met, the state of the corresponding switch in the segment-level topology model was adjusted from the currently recorded position to the target open / closed state. Based on the adjusted model, the electrical connectivity between the faulty and non-faulty sections, as well as the power supply path of the non-faulty sections, were re-analyzed. The analysis included checking whether all faulty sections were still connected to any power supply section through a conductive path, whether all non-faulty sections still had at least one power supply path from the power supply section to that section, and whether all sections marked as important users remained on a powered path.

[0062] In the typical urban substation operating condition of a low-voltage feeder short circuit, when the minimum disconnector set only includes the feeder switch of the faulty feeder, the fault isolation operation sequence constructed by the protection and control device usually only includes one step: after the upper-level maintenance personnel confirm permission through the dispatch or duty terminal, the faulty feeder switch is opened. During the hypothetical execution process, the state of the feeder switch in the section-level topology model is adjusted to open. The model calculation results show that the conductive path between the faulty feeder section and the other sections is completely cut off, while the power supply path of other feeder sections remains unchanged. At this time, the operation sequence is marked as acceptable. However, in some more complex operating conditions or with backup power supply, the minimum disconnector set may... If, during the hypothetical execution of a system containing multiple switches, the protection and control device detects that, after a certain step, the faulty section is still connected to the non-faulty section through an unopened controllable switch, or that some important non-faulty sections lose all power supply paths within a short period during intermediate steps, then the operation sequence is marked as unqualified. The sequence is then adjusted and retried within the switch combination space corresponding to the minimum isolating switch set. For example, the sequence could be adjusted to first activate the backup power supply-related tie switches, then open the faulty feeder and some tie switches, or first open the remote switch and then open the near switch, until a set of operation sequences is obtained that satisfies the condition of electrical isolation of the faulty section and maintenance of power supply to the non-faulty section after each hypothetical execution step.

[0063] After completing this round of hypothetical execution and sequence adjustment, the protection and control device will lock and store the final determined fault isolation operation sequence, along with the fault event number, section-level topology model version number, minimum disconnector set, and the aforementioned section fault identification results, in the fault event record area. This operation sequence can serve as the sequential basis and safety boundary for on-site operators when performing fault isolation, and can also be used as a chain to reproduce the entire fault handling process during post-event analysis.

[0064] In a city-type prefabricated substation with a rated voltage of 10,000 kV, using a single busbar segmented connection and equipped with some remote control ring network switches, when a short circuit occurs in a low-voltage feeder section and the minimum disconnector set only includes that feeder switch, the protection and control device can construct a fault isolation operation sequence that requires only one step, based on the condition that the remote selection of that feeder switch is in an allowed position and the associated interlocking signal is normal. After the hypothetical execution verification is passed, the sequence is directly locked as the recommended operation sequence for this fault. In other scenarios where power can be fed back to adjacent substations through ring network interconnection, a multi-step operation sequence can be constructed, which includes first closing a specific ring network switch, connecting the backup power supply, and then opening the faulty feeder switch and some interconnection switches. After internal hypothetical execution verification that there will be no fault reconnection or long-term power loss for important users between each step, the verified sequence is archived. Based on the above capabilities, those skilled in the art can fully implement this step in the field of a prefabricated substation that meets the aforementioned conditions of segment-level topology model construction, unified time synchronization, fault section identification, and minimum disconnector set determination.

[0065] S6. Control the switch to complete the opening and closing operations according to the fault isolation operation sequence, record the fault current changes and section voltage recovery status, and write the fault section set, minimum disconnecting switch set, and execution results into the fault handling record. The specific implementation is as follows: After the fault isolation operation sequence is locked, the protection and control device, constrained by the current section-level topology model version and fault event records, uses this operation sequence as the sole basis for action and performs remote operations on each switch in the controllable switch set in a predetermined order. Before executing a certain operation, the device first reads the current closing / opening position, local / remote selection status, and associated interlocking signals of the switch. The local / remote selection status refers to the state quantity reflecting whether the switch is currently allowed to issue remote control commands by the protection and control device, which is usually determined by the selection switch position and its feedback contacts on the local control box. The interlocking signal refers to the state quantity reflecting whether the electrical interlocking conditions and mechanical interlocking conditions are met, used to indicate whether the switch is allowed to perform opening / closing operations under the current bus voltage, current, or disconnector switch position.

[0066] Only when the switch is in a state that allows remote control and all associated interlocking signals are in a combination state that allows action, will the protection and control device issue a control command to the switch according to the predetermined target opening and closing state in the fault isolation operation sequence. After issuing the command, it waits for switch position feedback and action time feedback, and compares the final feedback position with the expected state to determine whether the operation step has been completed.

[0067] To ensure that each operation does not cause the switch to unintentionally flip multiple times due to duplicate or delayed messages in complex communication environments, the protection and control device pre-assigns a unique sequence number to each step in the fault isolation operation sequence and carries this sequence number along with the command sent to the switch. This sequence number is used in this manual to uniquely identify each operation step. During the same fault handling process, if the device detects that the operation corresponding to the sequence number has already been marked as completed in the fault handling record when monitoring feedback information from the field, it will not perform any new control on that step, but will treat this command as a duplicate arrival and skip the processing, thereby achieving deduplication of duplicate commands and idempotent control of the switch state.

[0068] To avoid prolonged delays in a particular operation due to short-term communication interruptions or switch malfunctions, the device assigns a sequence number to each command and sets an upper limit for the allowed waiting time for position feedback and a maximum number of retransmissions for that operation. The upper limit can be set to a second-level range that matches the on-site communication delay and the mechanical action time of the switch. The number of retransmissions is determined by those skilled in the art based on operational reliability requirements and the risk of malfunction. If no confirmation of a switch position change is received after the waiting time has elapsed, or if the received feedback status is inconsistent with the target status in the operation sequence, the device marks that operation as incomplete in the fault handling record and retransmits the command with the same sequence number before reaching the maximum number of retransmissions. This continues until the target status is still not met even after reaching the maximum number of retransmissions. In this case, the device stops executing subsequent automatic isolation steps, marks the automatic isolation status of this fault as incomplete, and no longer issues new action commands to other controllable switches.

[0069] For incomplete control fault events, the protection and control device writes the current segment-level topology model version, minimum set of disconnect switches, fault isolation operation sequence, and incomplete step markers into the fault handling record. Through a minimum set of interfaces agreed upon in advance with the dispatch master station or operation and maintenance system, the status is mapped to error markers such as model version mismatch, missing evidence chain identifier, or unexecutable isolation scheme. The minimum set of interfaces refers to a set of basic fields and status codes required by the superior system to identify the results of this method without exposing all internal details. This set is used to trigger manual takeover or other backup handling procedures on the superior system side.

[0070] Throughout the entire process of automatic isolation, the protection and control device continuously observes the changes in fault section current and non-fault section voltage over time using the aforementioned unified timing basis. In this specification, fault section current refers to the effective value of the three-phase current or its amplitude level measured in each section marked as a fault section by the aforementioned section fault identification results. Non-fault section voltage refers to the effective value of the voltage or its amplitude level in sections not included in the fault section set. The device records the process of the fault section current gradually decreasing from a high value to near the normal operating level before and after the isolation action, as well as the process of the non-fault section voltage recovering from a drop to a stable range, according to a preset time rhythm. These records are then compressed and organized to form a summary of fault current and voltage recovery curves that can reflect the fault clearing effect.

[0071] The summary of fault current and voltage recovery curves may include information such as current and voltage level changes at several key moments, recovery time, and whether secondary drops occurred during the recovery process. This information is used to provide the main quantitative basis required for subsequent analysis without increasing storage usage.

[0072] After the protection and control device completes all isolation actions or exits the automatic isolation process in the state of incomplete control, it writes the set of fault sections corresponding to this fault event, the set of minimum disconnect switches, the final fault isolation operation sequence, the completion status of each step in the sequence, the number of retries, and the summary of the above-mentioned fault current and voltage recovery curves into the fault handling record. The fault handling record is the name given in this manual to a set of stored records that record the entire process of a single fault from identification, scheme generation, operation execution to effect evaluation.

[0073] To ensure that each fault handling record is traceable and unambiguous, the protection and control device simultaneously associates the segment-level topology model version, fault evidence fingerprint version, scoring rule version, and isolation constraint rule version used in the fault handling record. Based on these version numbers and fault event numbers, a unique evidence chain identifier is generated. The evidence chain identifier is a unique marker used in this specification to indicate the combination of model, rules, and observation evidence on which the fault handling was based.

[0074] The dispatching master station or operation and maintenance system can call the evidence chain identifier and corresponding fault handling record through the interface agreed upon with the protection and measurement and control device, which can be used to reproduce the basis and process of this fault isolation in the upper-level system. When the upper-level system finds that the deviation between the unified time synchronization in the fault handling record and the current system time exceeds the preset allowable range when calling the interface, or finds that the version of the segment-level topology model, the version of the scoring rule, and the version of the isolation constraint rule are inconsistent with the version currently held by the upper-level system, the status will be regarded as a situation that does not meet the preconditions for the application of this method. Instead of automatically receiving or issuing new isolation schemes, it will be transferred to manual review or other protection logic according to the unit's operating procedures, thereby clarifying the security and compliance boundaries of this method in terms of time synchronization, communication time limits, and automatic control permissions.

[0075] In a city prefabricated substation with a rated voltage of 10,000 kV and a single busbar segmented connection, when a short circuit occurs in a low-voltage feeder section and the minimum disconnector set only includes that feeder switch, the protection and control device, after completing the aforementioned hypothetical execution and locking the fault isolation operation sequence which only includes the step of opening the feeder switch, can issue a tripping command provided that the remote permission of the switch is detected and the interlocking conditions are met. Within a limited feedback time, it will receive a status report that the switch has changed from closed to open. At the same time, it will observe that the current in that feeder section drops from the short-circuit current level to near zero, and the voltage of other feeder sections remains within the normal range. Finally, a complete chain of evidence is formed in the fault handling record, including the fault section set, the minimum disconnector set, the single-step operation result, and a summary of the current and voltage recovery process. Those skilled in the art can reproduce this step on-site in a prefabricated substation that meets the aforementioned conditions of segment-level topology model construction, unified time synchronization, fault section identification, minimum disconnector set determination, and fault isolation operation sequence generation.

[0076] In the operational scenario shown in this embodiment: In an urban box-type substation with a rated voltage of 10,000 kV and a single busbar sectionalized connection, before the box-type substation is put into operation, the operation and maintenance unit checks the high-voltage incoming switch, transformer high-voltage side switch, busbar sectionalizing switch, low-voltage feeder switch and the connected cable joints inside the box-type substation one by one according to the planning and design data and the as-built primary wiring diagram, to confirm that the on-site equipment numbers are consistent with the drawings and that the cable routes are clearly identifiable. Based on this, the section from the high-voltage incoming switch outlet to the high-voltage busbar connection point is designated as the incoming line section. The high-voltage busbar is divided into several busbar sections according to the location of the sectionalizing switches. The section from the high-voltage side connection of the transformer to the busbar connection point is designated as the high-voltage side section of the transformer. The section from the low-voltage side connection of the transformer to each low-voltage feeder switch is designated as the low-voltage busbar section and feeder section, respectively. Each incoming line, each busbar section, each high- and low-voltage side connection section of the transformer, and each feeder is assigned a unique section identifier. The voltage level, the type and rated parameters of the connected primary switches, the ratio and accuracy class of the configured current transformers and voltage transformers, the type of protection function installed, and the connection relationship with other sections are recorded. The above information is entered into the protection and control device inside the transformer substation. The device establishes a section-level topology model with sections as nodes and the conductive connections between sections as edges. It makes a unidirectional connection description for each upstream to downstream power supply path. After manual verification and trial operation, the model is assigned an initial version number and stored in a non-volatile storage medium. Meanwhile, the protection and control device is equipped with a unified time synchronization node, which periodically synchronizes with the dispatch automation system through a synchronous Ethernet channel, records the time synchronization deviation between the local clock and the reference time, sets the time synchronization deviation threshold to the millisecond level, and marks the transformer as an operating location with reliable time synchronization conditions if the deviation remains within the threshold for a long period of time, thus providing a basis for subsequent time sequence analysis of operating behavior.

[0077] During normal operation of the transformer substation, a phase-to-phase short-circuit fault occurred on the external user side of one of the low-voltage feeders during a peak load period. The overcurrent protection element located on this feeder section detected that the effective value of the three-phase current rapidly increased to several times the rated current, and the current amplitude level entered the highest preset level range. The protection element output a start-up flag and then an action flag within a very short time. Simultaneously with detecting the protection start-up flag for this feeder section, the protection and control device, based on the time reference provided by the unified timing node, takes the moment when the start-up flag first appears as the fault trigger moment, and sets a fault time window within a time range consisting of several power frequency cycles before and after this moment. Within the fault time window, the device continuously reads the protection start-up status, protection action status, effective values ​​of three-phase current and three-phase voltage, and the closing and opening status of each switch for all sections according to a fixed acquisition rhythm, adding a unified timing timestamp to each record. After the fault time window ends, the device organizes the collected records, removes or replaces isolated abnormal values ​​that are significantly beyond the range of the current transformer, fills in missing records at individual moments according to the measurement results of adjacent moments, and assigns the current and voltage of each measuring point to the corresponding interval according to the predefined amplitude level interval, forming standardized observation values ​​with interval division version identifiers.

[0078] After completing the above processing, the protection and control device divides the fault time window into a series of equally spaced discrete moments based on the timestamp. For each moment, the protection status, current level range, voltage level range, and related switch positions of all sections are aggregated to form an operating slice for that moment. Within each operating slice, the protection start-up status, protection operation status, current level range, voltage level range, and switch position of each section are encoded according to the section identifier, generating a fault evidence fingerprint for that section at that moment. The device statistically analyzes the distribution of protection start-up and operation flags in each operating slice within the fault time window and finds that in several operating slices centered on the low-voltage feeder protection operation moment, the faulty feeder section protection starts and operates, the upstream incoming line section protection starts but does not operate, and the protection in other sections does not start and the current and voltage are close to normal. The device selects the operating slice where the number of protection actions reaches its peak as the target operating slice, and writes the fault evidence fingerprints of all sections within the target operating slice, along with the fault event number, fault time window identifier, unified time reference information, section-level topology model version number, and fault evidence fingerprint version number, into the fault event record area, providing a complete field observation basis for subsequent fault section identification.

[0079] After obtaining the target operating slice, the protection and control device, under the current segment-level topology model version, proposes segment fault assumptions for each segment sequentially. For a given segment, it is assumed that a permanent short circuit or ground fault exists during this fault process, while the remaining segments remain in a non-fault state. The device, combining the segment's connection relationships with upstream and downstream segments in the topology model, the protection types and setting ranges configured for each segment, and the power supply direction information, derives the protection initiation state, protection operation state, current level, voltage level, and related switch positions that each segment should exhibit at the corresponding time in the target operating slice, forming a theoretical event mode. For a fault segment assumption located within a low-voltage feeder, the theoretical event mode typically requires that the feeder segment's current level be in the highest level range, the voltage level drop to the lowest level range, the feeder switch protection be initiated and operated, the upstream incoming line segment's current level increase, the voltage level fluctuate slightly, the incoming line direction protection be initiated but not operated, and the bus section segment and other non-faulty feeder segments maintain current and voltage levels within the normal range. The device compares each theoretical event mode with the fault evidence fingerprint of the corresponding segment in the target operating slice item by item. It assigns quantitative scores to the protection initiation status, protection operation status, current level, voltage level, and switch position results according to pre-configured scoring rules. Points are added to items with obvious consistency, and deducted from items with obvious inconsistencies according to weight, resulting in a score record corresponding to each segment fault hypothesis. The device sorts all segment scores by size, removes segments with scores below a threshold, and, based on topological continuity constraints, prioritizes retaining segments that are adjacent to each other in the segment-level topology model, can form a continuous conductive path, and have a higher score level. Single feeder segments with scores significantly higher than other candidates are identified as the fault segment set for this fault. The fault segment set, the score level of each segment, the version number of the scoring rule used, the fault event number, the version number of the segment-level topology model, and the version number of the fault evidence fingerprint are all stored in the fault event record area, forming the segment fault identification result.

[0080] When the fault identification results include only one low-voltage feeder section as the fault section set, the protection and control device searches the section-level topology model for low-voltage feeder switches directly connected to the faulty feeder section, bus sectionalizing switches connected to the bus section where the feeder is located, and upstream high-voltage incoming line switches. It further filters switches with remote operation capability and within the control authority of the device to form a controllable switch set. The device checks the combination of controllable switch open / closed states according to pre-configured isolation constraint rules, requiring at least one open controllable switch on each electrical connection path between the faulty feeder section and other non-faulty sections. Sections containing important users are prioritized to remain on the power supply side. The combination result does not form isolated power islands and does not violate existing protection direction configurations and operating procedures. In scenarios involving single-feeder faults where backup power is not immediately activated, the device can generate various switch opening and closing combinations that satisfy isolation constraints within the combination space. The combination that only opens the faulty feeder switch while keeping the bus section switch and high-voltage incoming switch inactive requires the fewest opening actions and is therefore identified as the minimum disconnector switch set. The device writes the unique feeder switch identifier in this set, its expected opening state, the version number of the adopted isolation constraint rule, and the scoring information from the fault section set and section fault identification results into the fault event record area, serving as the basis for subsequently generating the fault isolation operation sequence.

[0081] After the minimum set of disconnecting switches is determined, the protection and control device reads the actual closing and opening positions, local and remote selection status, and related interlocking signals of each switch in the controllable switch set. This confirms that the feeder switches in the minimum set of disconnecting switches are in a remote control-allowed state and that all interlocking signals are in an action-allowed state. The device, combined with the power supply line location and load distribution of each feeder in the section-level topology model, constructs a fault isolation operation sequence for this fault. In this embodiment, since only one opening operation on the faulty feeder switch is needed to satisfy the isolation constraint, the fault isolation operation sequence contains only one step: after the superior maintenance personnel confirm permission through the duty terminal, a one-time opening operation is performed on the faulty feeder switch. The device internally simulates the execution of this operation sequence. In the segment-level topology model, the state of the faulty feeder switch is changed from closed to open. The conductive paths between the faulty feeder segment and the non-faulty segment are re-analyzed, confirming that all connecting paths between the faulty feeder segment and the other segments have been severed. Other feeder segments still receive power through transformers and busbar segments, and important user segments remain on energized paths. The above analysis results show that this single-step operation sequence meets the requirements of electrical isolation of the faulty segment and maintenance of power supply to the non-faulty segment. Based on this, the protection and control device locks and stores this sequence, along with the fault event number, segment-level topology model version number, minimum disconnector set, and segment fault identification results, in the fault event record area as the recommended operation sequence for this fault isolation.

[0082] After the fault isolation operation sequence is locked, the protection and control device uses this sequence as the sole basis for action and issues a remote tripping command to the feeder switch in the minimum disconnector switch set. Before issuing the command, the device re-checks the current closing / opening position, local / remote selection status, and interlocking signal of the switch. Only when the switch is in a state that allows remote control and the interlocking conditions are met will the device send a tripping command to the switch control circuit and assign a unique operation sequence number to this step to achieve deduplication control in the event of communication duplication or delay. After sending the command, the device waits for switch position feedback and action time feedback within a preset time limit. When it detects that the feeder switch status has changed from closed to open and the feedback action time falls within the expected range, the device marks this step as completed in the fault handling record. If no feedback is received within the waiting time or the feedback status is inconsistent with the target status, a limited number of retransmissions are performed according to the preset maximum number of retransmissions. Under normal operating conditions in this embodiment, the faulty feeder switch successfully completes the tripping under the first command without triggering the retry logic.

[0083] During the isolation process, the protection and control device continuously observes the effective value and amplitude level changes of the three-phase current in the faulty feeder section under unified timing conditions, records the process of the current rapidly decreasing from the short-circuit current level to near zero, and simultaneously records the process of the voltage in other non-faulty feeder sections recovering from the short-term drop that may occur at the time of the fault to the steady-state range. These records are compressed to form a summary of the fault current and voltage recovery curves. After completing all isolation actions, the device writes the set of faulty sections corresponding to this fault event, the minimum set of disconnecting switches, the final fault isolation operation sequence, the completion status of each step in the sequence, the number of retries, and the summary of the fault current and voltage recovery curves into the fault handling record. The record also associates the section-level topology model version, fault evidence fingerprint version, scoring rule version, and isolation constraint rule version used in this handling, generating a unique evidence chain identifier based on these version numbers and the fault event number. After the incident, the dispatch master station can access the evidence chain identifier through the interface agreed upon with the protection and control devices. This allows them to view the complete process of the fault, from section division, unified time synchronization, fault evidence fingerprint construction, section fault identification, determination of the minimum disconnector set, generation of fault isolation operation sequence, to actual isolation action execution and effect evaluation. Those skilled in the art, in a prefabricated substation site that meets the aforementioned requirements for section-level topology model construction, reliable time synchronization, reasonable protection configuration, and communication link time limits, can construct a protection and control system with fault section identification, automatic fault isolation scheme generation, and safe execution capabilities by referring to the steps and parameter settings of this embodiment. This enables rapid fault isolation integrating protection and control in prefabricated substations.

[0084] All calculations involved in the embodiments are dimensionless numerical calculations, and the preset parameters and thresholds in the calculations are set by those skilled in the art according to the actual situation.

[0085] It should be noted that this invention can be deployed on the device itself to realize embedded applications, or it can run on a PC or other terminal with a user interface, thereby meeting various hardware environments and usage requirements.

[0086] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wireless or wired transmission; wired transmission methods include optical fiber, twisted pair, coaxial cable, etc.; wireless transmission includes infrared, microwave, etc. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center containing one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0087] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0088] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0089] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0090] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0091] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0092] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0093] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rapid fault isolation method integrating protection and measurement / control in a prefabricated substation, characterized in that, include: S1. Divide the substation into sections based on primary switches and cable joints, establish a section-level topology model and configure unified time synchronization. S2. When any section protection device outputs at least one of the start flag and action flag, collect the protection status, measurement value and switch status of each section within the fault time window, align them according to the time synchronization to form an operation slice, and identify them as fault evidence fingerprints according to the section. S3. Propose fault hypotheses for each section, derive theoretical event modes based on the section-level topology model and protection configuration, compare the theoretical event modes with fault evidence fingerprints, calculate scores, and determine the set of fault sections based on the score results and topology continuity constraints. S4. Based on the set of fault sections, select controllable switches around the fault sections according to the topology model, construct isolation constraints, and solve to obtain the minimum set of isolation switches that satisfy the constraints. S5. Generate a fault isolation operation sequence based on the minimum set of disconnecting switches and the current switch state. After each step is hypothetically executed, update the segment-level topology model and check that the faulty segment is isolated and the power supply to the non-faulty segment is maintained. After determining the minimum set of disconnecting switches, the protection and control device reads the closing and opening positions, local and remote selection status, and interlocking signals of the controllable switches. The target state and prerequisite conditions of each switch in the fault isolation operation sequence are determined based on the segment-level topology model and the minimum set of disconnecting switches. When the preconditions are met, the fault isolation operation sequence is hypothetically executed in the segment-level topology model and the switch status and power supply path are updated. After confirming that the faulty segment is in an electrically isolated state and the non-faulty segment is in a power supply state, the fault isolation operation sequence is written into the fault event record area. S6. Control the switch to complete the opening and closing operations according to the fault isolation operation sequence, record the changes in fault current and the recovery status of section voltage, and write the fault section set, the minimum disconnecting switch set and the execution result into the fault handling record.

2. The rapid fault isolation method for integrated protection and measurement and control of a prefabricated substation according to claim 1, characterized in that, S1 includes: Based on the wiring diagram and on-site survey results, the sections are divided with the high-voltage incoming switch, the high-voltage side switch of the transformer, the bus section switch, the low-voltage feeder switch and the cable joint as the electrical boundaries. Each section is identified, and its voltage level, connection relationship, and protection function are registered to form a section-level topology model in the protection and control device. The protection and control device is set as a unified timing node. The time reference is obtained from an external time source and the timing deviation is recorded. When the timing deviation exceeds the timing deviation threshold, the fault section identification step that depends on the time sequence is stopped, and the tripping action is performed according to the existing short circuit protection setting.

3. The rapid fault isolation method integrating protection and measurement and control in a prefabricated substation according to claim 1, characterized in that, S2 include: When the protection and control device outputs at least one start flag or action flag in any section of the protection device, the fault time window is determined according to the unified time synchronization. Within the fault time window, the section protection status, current value, voltage value and primary switch status are collected and timestamped. After alignment, the operation slices are divided. Before forming the running slice, the collected values ​​are processed according to the pre-configured sorting rules and the current and voltage values ​​are classified into amplitude level ranges; Within the running slice, the protection start-up status, protection action status, voltage level range, current level range, and primary switch position associated with the corresponding segment are aggregated according to the segment identifier to form a fault evidence fingerprint with a version number and written into the fault event record area.

4. The rapid fault isolation method for integrated protection and measurement and control in a prefabricated substation according to claim 1, characterized in that, S3 includes: For each segment in the segment-level topology model, the protection and control device proposes segment fault hypotheses based on the target operation slice after the fault time window ends; Under the premise that this section is assumed to be a fault section, a theoretical event mode is constructed that includes protection initiation status, protection operation status, current level, voltage level and related primary switch status. The theoretical event patterns are compared item by item with the fault evidence fingerprints in the target running slice, and a scoring record containing segment identifiers and scoring levels is generated according to the pre-configured scoring rules.

5. The rapid fault isolation method for integrated protection and measurement and control of a prefabricated substation according to claim 4, characterized in that: The protection and control device sorts the scoring records of all sections according to the scoring level, sets a scoring threshold, removes sections with scores below the scoring threshold, and selects sections with scores above the scoring threshold as candidate fault sections. Topological continuity constraints are applied between candidate fault segments, and the combination of candidate fault segments is determined as a set of fault segments only when the candidate fault segments form a continuous conductive path in the segment-level topology model.

6. The rapid fault isolation method integrating protection and measurement and control in a prefabricated substation according to claim 1, characterized in that, S4 includes: After obtaining the set of fault sections, the protection and control device selects primary switches that are directly connected to the set of fault sections and connected through adjacent non-fault sections not exceeding the preset maximum number of jumps, based on the section-level topology model, to form a set of controllable switches. Construct isolation constraints to limit the number of controllable switches in the open state on each electrical connection path between faulty and non-faulty sections, keep sections marked as important users on the power supply side, prevent the formation of isolated power supply islands, and ensure that existing protection direction configurations and switch operation procedures are not violated. Under isolation constraints, the combination of controllable switch open and closed states is searched, and the combination with the minimum number of required open switches is selected as the minimum isolation switch set.

7. The rapid fault isolation method for integrated protection and measurement and control of a prefabricated substation according to claim 6, characterized in that: When a backup power supply is available, the protection and control device identifies the interconnecting switches and switching switches associated with the backup power supply from the set of controllable switches. Based on the allowable capacity range of the backup power supply, the upper limit of the load of the non-faulty section powered by the backup power supply is determined. Under the condition that the capacity constraint and the isolation constraint are satisfied at the same time, the combination of controllable switch opening and closing states is searched step by step. The combination with the fewest number of tripped switches under the premise of maintaining power supply to the non-faulty section is selected as the minimum isolation switch set under the participation of the backup power supply.

8. The rapid fault isolation method integrating protection and measurement and control in a prefabricated substation according to claim 1, characterized in that, S6 include: After the fault isolation operation sequence is locked, the protection and control device uses the fault isolation operation sequence as the sole basis for action to gradually perform remote opening and closing operations on the controllable switch. Before each step is executed, if the local / remote selection status of the target switch and the interlocking signal are in an allowed combination state, a control command with a unique sequence number is sent, and the completion status of the step is marked according to the switch position feedback. If the waiting time limit is exceeded and the retransmission reaches the upper limit, the control is marked as incomplete and subsequent automatic isolation is stopped. In the fault handling record, the evidence chain identifier is generated by associating the segment-level topology model version, fault evidence fingerprint version, scoring rule version, and isolation constraint rule version, and is then called by the superior system.

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