Fault identification method and system based on zero-sequence current and storage medium thereof

Abstract

The invention discloses a fault identification method and system based on zero-sequence current and a storage medium thereof, and belongs to the technical field of hot reverse bus bar anti-misoperation, and the method comprises the steps: constructing a transformer substation double-bus-coupler equivalent model; executing a hot reverse operation fault identification action; obtaining first three-phase current change data and second three-phase current change data; acquiring first zero-sequence current data based on the first three-phase current change data, and acquiring second zero-sequence current data based on the second three-phase current change data; obtaining a first bus state variable and a first line state variable, and obtaining a second bus state variable and a second line state variable; and obtaining an output fault identification result based on a preset fault matching library. According to the fault identification method and system based on the zero-sequence current and the storage medium, the technical problems of accuracy defects and misjudgment risks in the prior art can be solved, and accurate identification of faults occurring in the hot reverse bus operation of a transformer substation is achieved.

Description

Technical Field

[0001] This invention relates to the field of thermal busbar fault prevention technology, and in particular to a fault identification method, system and storage medium based on zero-sequence current. Background Technology

[0002] With the continuous expansion of urban power grids and the increasing automation of control, substation operation is rapidly transforming from traditional on-site manual operation to remote centralized control and intelligent dispatching. Double busbar connection, with its significant advantages of flexible power switching and high operational reliability, is widely used in substations with voltage levels of 220 kV and above. In a double busbar connection structure, hot busbar switching is a core step in the daily operation, maintenance, and accident handling of substations, and its correctness directly affects the continuity of power supply and the safe and stable operation of the power grid. Hot busbar switching must strictly follow the established sequence of closing the bus tie circuit breaker, closing the switching bay disconnector, disconnecting the original busbar side disconnector, and disconnecting the bus tie circuit breaker. Among these, the disconnector, as a key link in electrical connection, although a no-load operating device, is a prerequisite for ensuring the complete implementation of the entire hot busbar switching operation chain. However, due to the combined effects of the disconnector's own structural characteristics and the on-site operating environment, in actual operation, the disconnector is prone to problems such as mechanical jamming, abnormal control logic, or aging mechanical parts, resulting in incomplete closing. If such abnormal conditions are not identified and handled in a timely manner, they can easily lead to faults such as arcing breakdown and contact erosion during subsequent load switching or fault conditions. In severe cases, they may also cause protection maloperation, main equipment tripping, or even trigger bus differential protection maloperation, posing a major safety hazard to the power grid operation.

[0003] Currently, on-site monitoring of disconnector status mainly relies on various auxiliary information methods, including video image recognition devices, disconnector position indication mechanisms, secondary circuit status signals, and telemetry equipment in some substations. However, these monitoring methods all have significant limitations in practical applications: video image recognition is limited by the training accuracy of the recognition algorithm and on-site lighting conditions. When there are situations such as angle obstruction, insufficient light, or camera equipment malfunction, the recognition results are prone to misjudgment or omission, making it difficult to guarantee monitoring accuracy; disconnector position indication mechanisms may cause inconsistencies between the disconnector status fed back and the actual closure status of the main circuit contacts due to problems such as mechanical rebound, contact jitter, or signal drift, failing to truly reflect the disconnector's operating status; at the same time, remote signaling and telemetry signals that rely on communication transmission are easily affected by delays, packet loss, or electromagnetic interference during transmission, making it difficult to achieve rapid and accurate identification of disconnector status and failing to meet the real-time requirements of hot busbar switching operations.

[0004] While some literature proposes using electrical characteristics to identify incomplete disconnection of disconnectors, these solutions only address the stage after the disconnector has closed. Furthermore, when an asymmetrical grounding fault occurs, a large zero-sequence current is generated in the system's zero-sequence network, which interferes with the judgment results of the aforementioned criteria, causing them to fail. Therefore, to address the accuracy deficiencies and misjudgment risks of existing monitoring methods, there is an urgent need to develop a more comprehensive disconnector status identification technology based on the electrical response characteristics of equipment. This technology can accurately identify faults such as incomplete disconnection and asymmetrical grounding during hot busbar switching operations. Summary of the Invention

[0005] This invention provides a fault identification method, system, and storage medium based on zero-sequence current, which can solve the technical problems of inaccuracy defects and misjudgment risks in the prior art, and realize accurate identification of faults that occur in substations during hot bus switching operations.

[0006] This invention provides a fault identification method based on zero-sequence current, comprising: Construct an equivalent model of a substation dual busbar connection based on actual substation data; Based on the equivalent model of the substation's dual busbar connection, perform hot-swap operation fault identification actions: The equivalent model of the substation with dual busbars is controlled to enter the first acquisition stage to acquire the first three-phase current change data. The equivalent model of the substation with dual busbars is controlled to enter the second acquisition stage to acquire the second three-phase current change data. First zero-sequence current data is obtained based on the first three-phase current change data, and second zero-sequence current data is obtained based on the second three-phase current change data. The first bus state variable and the first line state variable are obtained based on the first three-phase current change data, the first zero-sequence current data and the preset elastic threshold. The second bus state variable and the second line state variable are obtained based on the second three-phase current change data, the second zero-sequence current data and the preset elastic threshold. The output fault identification result is obtained by matching the first bus status variable, the first line status variable, the second bus status variable, and the second line status variable based on the preset fault matching library.

[0007] This invention provides a fault identification method based on zero-sequence current. First, an equivalent model of a substation with dual busbars is constructed to simulate the hot-swap operation process of an actual substation. Then, during the simulated hot-swap operation, three-phase current change data is collected in stages to capture the differences in current characteristics at different operation stages. This allows for differentiation between whether the circuit breaker is properly closed and asymmetrical grounding faults, avoiding misjudgments. Next, the corresponding zero-sequence current is calculated, and based on it and a preset elastic threshold, the state variables on the busbars and lines within the two acquisition stages are calculated and analyzed. Continuous current data is transformed into discrete states indicating whether limits are exceeded. Finally, a matching method based on a preset fault matching library and the obtained state variables is used to obtain accurate fault identification results, effectively improving identification efficiency. This method solves the accuracy deficiencies and misjudgment risks existing in the prior art, achieving accurate identification of faults occurring during hot-swap busbar operations in substations.

[0008] Furthermore, the construction of the equivalent model of the substation dual busbar based on actual substation data includes: An equivalent model of a substation with dual busbars is constructed based on actual substation data and pre-defined disconnector arc models. The equivalent model of the substation with dual busbars includes the first busbar, the second busbar, the busbar branch, and the disconnector branch; The first busbar and the second busbar are electrically connected through the bus tie branch; The bus tie branch includes a bus tie circuit breaker and a bus tie current transformer connected in series. The disconnector branch includes a primary disconnector, a target disconnector, and a line current transformer, wherein: the first end of the primary disconnector is electrically connected to the first busbar, the first end of the target disconnector is electrically connected to the second busbar, the second end of the primary disconnector is electrically connected to the second end of the target disconnector, the second end of the target disconnector is electrically connected to the first end of the line current transformer, and the second end of the line current transformer serves as the load output end of the disconnector branch.

[0009] In the above scheme, the hot busbar switching process in the actual operation is simulated by constructing an equivalent model of the substation with dual busbars. This enables the simulation of the substation's hot busbar switching disconnect switch closing in place, disconnect switch not closing in place, and the occurrence of system asymmetrical grounding fault conditions.

[0010] Further, the control of the substation double-bus equivalent model enters the first acquisition stage to acquire the first three-phase current change data, including: Acquire the first acquisition signal of hot-swap operation, and control the bus tie disconnect device to be in a closed state based on the first acquisition signal of hot-swap operation, so as to control the substation double bus tie equivalent model to enter the first acquisition stage; The first line three-phase current is obtained based on the line current meter, and the first bus three-phase current is obtained based on the bus tie current meter. Acquire the second acquisition signal for hot-swap operation, and control the target switch to be in a closed state based on the second acquisition signal for hot-swap operation; The second line three-phase current is obtained based on the line current meter, and the second bus three-phase current is obtained based on the bus tie current meter. The change in the three-phase current of the first busbar is obtained based on the three-phase current of the first busbar and the three-phase current of the second busbar. The change in the three-phase current of the first line is obtained based on the three-phase current of the first line and the three-phase current of the second line. The changes in the three-phase current of the first busbar and the changes in the three-phase current of the first line are used as the first three-phase current change data.

[0011] Furthermore, the control of the substation double-bus equivalent model enters the second acquisition stage to acquire the second three-phase current change data, including: Acquire the third acquisition signal of the hot switch operation, and control the original disconnector to be in the open state based on the third acquisition signal of the hot switch operation, so as to control the substation double bus tie equivalent model to enter the second acquisition stage; The three-phase current of the third line is obtained based on the line current meter, and the three-phase current of the third bus is obtained based on the bus tie current meter. The change in the three-phase current of the second busbar is obtained based on the three-phase current of the third busbar and the three-phase current of the second busbar. The change in the three-phase current of the second line is obtained based on the three-phase current of the third line and the three-phase current of the second line. The change in the three-phase current of the second busbar and the change in the three-phase current of the second line are used as the data for the change in the second three-phase current.

[0012] In the above scheme, data collection is carried out in two stages by disassembling the hot-swap operation, covering the key nodes of the hot-swap operation, and providing complete data support for distinguishing between incomplete closing and asymmetrical grounding faults.

[0013] Further, the step of obtaining the first bus state variable and the first line state variable based on the first three-phase current change data, the first zero-sequence current data, and the preset elastic threshold, and obtaining the second bus state variable and the second line state variable based on the second three-phase current change data, the second zero-sequence current data, and the preset elastic threshold, includes: The first three-phase current change data includes the change in the three-phase current of the first bus and the change in the three-phase current of the first line, and the first zero-sequence current data includes the change in the zero-sequence current of the first bus and the change in the zero-sequence current of the first line. The first bus index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the first bus. The first line index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the first line. The second three-phase current change data includes the change in the three-phase current of the second bus and the change in the three-phase current of the second line; the second zero-sequence current data includes the change in the zero-sequence current of the second bus and the change in the zero-sequence current of the second line. The second bus index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the second bus. The second line index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the second line. The first busbar state variable is obtained by judging the state based on the first busbar index and the preset elastic threshold; the second busbar state variable is obtained by judging the state based on the second busbar index and the preset elastic threshold. Based on the first line indicator and the preset elastic threshold, a state judgment is made to obtain the first line state variable; based on the second line indicator and the preset elastic threshold, a state judgment is made to obtain the second line state variable.

[0014] Further, the step of obtaining the output fault identification result based on the preset fault matching library by matching the first bus state variable, the first line state variable, the second bus state variable, and the second line state variable includes: Perform a logical AND operation on the first bus state variable and the first line state variable to obtain the first state variable; The second state variable is obtained by performing an XOR operation on the first bus state variable and the first line state variable. A third state variable is obtained by performing a logical AND operation on the second bus state variable and the second line state variable. The fourth state variable is obtained by performing an XOR operation on the second bus state variable and the second line state variable. When the first matching condition is met based on the first state variable and the third state variable, the fault identification result output by the preset fault matching library is: there is an asymmetrical grounding fault. When the second matching condition is met based on the first and third state variables, the following further judgment action is executed: When the third matching condition is met based on the second and fourth state variables, the fault identification result output by the preset fault matching library is: there is a disconnector that is not fully closed; When the fourth matching condition is met based on the second and fourth state variables, the fault identification result output by the preset fault matching library is: the disconnector is closed in place.

[0015] In the above scheme, when the disconnector is fully closed, the bus and line indicators at both the bus tie branch and the disconnector branch will not exceed the preset elastic threshold. When the disconnector is not fully closed (usually a single-phase disconnection), the three-phase load imbalance will lead to three-phase current imbalance, resulting in a relatively large zero-sequence current. At this time, the line indicators at the disconnector will exceed the preset elastic threshold, that is, the indicators of the bus tie branch in the first acquisition stage and the disconnector branch in the second acquisition stage will exceed the preset elastic threshold. When an asymmetrical grounding fault occurs, the indicators will exceed the threshold regardless of the stage. This method achieves the identification of disconnector failure to close and the identification of asymmetrical grounding faults by collaboratively analyzing the characteristic differences of the indicators obtained by normalizing the monitoring points in the first and second acquisition stages. At the same time, by first determining whether an asymmetrical grounding fault exists and then determining the closing status through hierarchical fault matching, the three core operating conditions can be accurately distinguished, solving the technical problem that traditional methods cannot distinguish between disconnection failure and asymmetrical grounding faults, and ensuring the accuracy of fault identification results.

[0016] Furthermore, when the output shows a fault identification result indicating an asymmetrical grounding fault, a fault clearing action is triggered.

[0017] Furthermore, when a fault identification result indicating that the disconnector is not fully closed is output, the relevant protection actions are triggered to lock out the circuit breaker.

[0018] In the above scheme, by setting fault handling and protection actions, the fault clearing action is triggered when there is an asymmetrical grounding fault, and the relevant protection action is triggered when the disconnector fails to close properly. This avoids the fault from expanding and causing serious consequences such as main equipment tripping and busbar damage, improves the timeliness and safety of power grid fault response, ensures the safety of hot switching operation, and reduces system safety hazards.

[0019] This invention provides a fault identification system based on zero-sequence current, used to implement the aforementioned fault identification method based on zero-sequence current, comprising: The model building module is used to build an equivalent model of a substation with dual busbars based on actual substation data. The fault identification module is used to perform hot-swap operation fault identification actions based on the equivalent model of the substation's double busbars: controlling the equivalent model of the substation's double busbars to enter the first acquisition stage to acquire first three-phase current change data; controlling the equivalent model of the substation's double busbars to enter the second acquisition stage to acquire second three-phase current change data; acquiring first zero-sequence current data based on the first three-phase current change data, and acquiring second zero-sequence current data based on the second three-phase current change data; acquiring first busbar state variables and first line state variables based on the first three-phase current change data, first zero-sequence current data, and a preset elastic threshold; acquiring second busbar state variables and second line state variables based on the second three-phase current change data, second zero-sequence current data, and the preset elastic threshold; and acquiring the output fault identification result based on the matching of the first busbar state variables, first line state variables, second busbar state variables, and second line state variables based on a preset fault matching library.

[0020] The present invention also provides a storage medium, comprising: a stored computer program, wherein, when the computer program is executed, the device in which the storage medium is located executes the above-described fault identification method based on zero-sequence current.

[0021] The implementation of this invention has the following beneficial effects: By collecting three-phase current changes in stages and calculating normalized indices, interference from system load and operating mode is eliminated, ensuring that current characteristics accurately reflect operational anomalies and faults; by comparing data from two acquisition stages and designing a logic operation matching mechanism, effective differentiation between incomplete closing and asymmetrical grounding faults is achieved, solving the problems of misjudgment and omission in traditional methods; after fault identification, linked handling actions are taken to avoid the risk of protection malfunction and equipment damage, improving the safety of hot busbar operation and the reliability of power grid operation; engineering feasibility: at the same time, when constructing the equivalent model, it is based on the existing current device, without the need to add equipment, which facilitates actual deployment and reduces the cost of modification and implementation difficulty. Attached Figure Description

[0022] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a fault identification method based on zero-sequence current provided in this embodiment; Figure 2 This is a schematic diagram of the substation topology of the 220kV substation double busbar equivalent model provided in this embodiment; Figure 3This is a schematic diagram of the zero-sequence current waveform during the two stages of incomplete closing provided in this embodiment; Figure 4 This is a schematic diagram of the zero-sequence current waveform at the detection point during a single-phase ground fault, provided in this embodiment. Figure 5 This is a schematic diagram of the identification and judgment process for incomplete closing of the hot busbar disconnect switch based on the difference in zero-sequence current characteristics provided in this embodiment. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0026] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0027] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0028] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0029] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0030] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0031] This embodiment provides a fault identification method based on zero-sequence current. For details, please refer to [link to relevant documentation]. Figure 1 ,include: S01. Construct an equivalent model of a substation dual busbar connection based on actual substation data; S02. Perform hot-swap operation fault identification based on the equivalent model of the substation's dual busbar connection: S21. Control the substation double busbar equivalent model to enter the first acquisition stage and acquire the first three-phase current change data; S22. Control the substation double busbar equivalent model to enter the second acquisition stage and acquire the second three-phase current change data; S23. Obtain first zero-sequence current data based on the first three-phase current change data, and obtain second zero-sequence current data based on the second three-phase current change data; S24. Based on the first three-phase current change data, the first zero-sequence current data and the preset elastic threshold, obtain the first bus state variable and the first line state variable; based on the second three-phase current change data, the second zero-sequence current data and the preset elastic threshold, obtain the second bus state variable and the second line state variable. S25. Based on the preset fault matching library, obtain the output fault identification result of matching the first bus status variable, the first line status variable, the second bus status variable and the second line status variable.

[0032] This embodiment provides a fault identification method based on zero-sequence current. First, an equivalent model of a substation with dual busbars is constructed to simulate the hot-swap operation process of an actual substation. Then, during the simulated hot-swap operation, three-phase current change data is collected in stages to capture the differences in current characteristics at different operation stages. This allows for differentiation between whether the circuit breaker is properly closed and asymmetrical grounding faults, avoiding misjudgments. Next, the corresponding zero-sequence current is calculated, and based on it and a preset elastic threshold, the state variables on the busbars and lines within the two acquisition stages are calculated and analyzed. Continuous current data is transformed into discrete states indicating whether limits are exceeded. Finally, a matching method based on a preset fault matching library and the obtained state variables is used to obtain accurate fault identification results, effectively improving identification efficiency. This method solves the accuracy defects and misjudgment risks existing in the prior art, achieving accurate identification of faults occurring during hot-swap busbar operations in substations.

[0033] Optionally, step S01 includes: An equivalent model of a substation with dual busbars is constructed based on actual substation data and pre-defined disconnector arc models. The equivalent model of the substation with dual busbars includes the first busbar, the second busbar, the busbar branch, and the disconnector branch; The first busbar and the second busbar are electrically connected through the bus tie branch; The bus tie branch includes a bus tie circuit breaker and a bus tie current transformer connected in series. The disconnector branch includes a primary disconnector, a target disconnector, and a line current transformer, wherein: the first end of the primary disconnector is electrically connected to the first busbar, the first end of the target disconnector is electrically connected to the second busbar, the second end of the primary disconnector is electrically connected to the second end of the target disconnector, the second end of the target disconnector is electrically connected to the first end of the line current transformer, and the second end of the line current transformer serves as the load output end of the disconnector branch.

[0034] In the specific implementation process, an equivalent model of the substation's dual busbars is constructed based on the disconnector arc model. Simulations of the hot busbar switching process are conducted, divided into three stages according to the operational sequence: Stage 1 is from closing the bus tie circuit breaker to closing the target disconnector; Stage 2 is from closing the target disconnector to opening the original busbar disconnector; and Stage 3 is from opening the original busbar disconnector to disconnecting the bus tie circuit breaker. Within this process, a first acquisition stage and a second acquisition stage are established to enable subsequent hot busbar switching fault identification actions. This involves simulating the substation's hot busbar disconnector closing in place, disconnector not closing in place, and the occurrence of a system asymmetrical grounding fault. In the first and second acquisition stages, three-phase current and its changes are acquired from the bus tie current meter and line current meter, respectively.

[0035] Specifically, considering the potential arc breakdown phenomenon during closing of the disconnector gap, this embodiment uses the Mayr model as the preset disconnector arc model based on actual substation data (i.e., the actual substation's circuit structure, related parameters, etc.). An equivalent model of the substation's double bus tie is established based on the Mayr model, with code written using MATLAB / Simulink's function module. The closing and non-closing processes of the target disconnector and the original disconnector are controlled by moving the contacts of the target and original disconnectors. The entire process is divided into three stages according to the operation sequence: Stage 1 is from closing the bus tie circuit breaker to closing the target disconnector; Stage 2 is from closing the target disconnector to opening the original bus side disconnector; Stage 3 is from opening the original bus side disconnector to disconnecting the bus tie circuit breaker. The first acquisition stage is from closing the target disconnector to opening the original bus side disconnector, and the second acquisition stage is from opening the original bus side disconnector to disconnecting the bus tie circuit breaker.

[0036] In specific implementation, this embodiment takes a 220kV substation hot busbar switching scenario with a double busbar connection as an example. This includes two 500kV transmission lines connected to the 220kV busbar via a step-down transformer. The 220kV side has a double busbar structure (including a first busbar and a second busbar), a bus tie circuit breaker (in this embodiment, a bus tie circuit breaker), a bus tie current transformer forming a bus tie branch, and a disconnector branch. The disconnector branch supplies power to distant loads through several 220kV outgoing circuits. The load on the two busbars is uneven. Based on this, the substation topology of the 220kV substation double bus tie equivalent model is as follows: Figure 2 As shown, the system includes the first busbar (section I), the second busbar (section II), six lines with total currents of I1 to I6 (i.e., the disconnector branches), the bus tie circuit breaker QF on the bus tie branch, and the circuit breakers on the incoming and outgoing lines (the switching bay QF1 marked in the figure will be used as an example for subsequent analysis) and the corresponding disconnectors (target switching QS11 and original disconnector QS12). The blue dashed circle in the figure indicates the location of the current transformers (including the line current transformer CT1 on the disconnector branch and the bus tie current transformer CT2 on the bus tie branch) from which the three-phase current data is extracted in this embodiment.

[0037] Before the fault identification action of the hot busbar switching operation begins, the bus tie circuit breaker is in the open state, and the bus disconnectors QS01 and QS02 on both sides are in the closed state. Lines L1~L3 are running on busbar I, and lines L4~L6 are running on busbar II. For the switching line L6, disconnector QS12 is in the closed state, and disconnector QS11 is in the open state. Now, the second busbar needs to be inspected without power interruption. Therefore, all incoming and outgoing lines on the second busbar need to be switched to the first busbar. Taking line L6 as an example, the specific operation is as follows: First, close the bus tie circuit breaker QF to achieve equipotential between the two busbars. Then, close disconnector QS11 on the first busbar side, open the originally closed disconnector QS12 on the second busbar side, and finally open the bus tie circuit breaker to carry out the grounding wire inspection of the second busbar.

[0038] For ease of analysis and explanation, this embodiment applies the aforementioned equivalent model of the substation double busbar to the disconnector QS11 to simulate the disconnector closing process. The three-phase disconnector closing is controlled by a custom module of the arc model. Considering that the probability of incomplete closing occurring in two or more phases is very small, this embodiment only studies single-phase incomplete closing, specifically taking the incomplete closing of phase A disconnector as an example for analysis.

[0039] Optionally, step S21 includes: Acquire the first acquisition signal of hot-swap operation, and control the bus tie disconnect device to be in a closed state based on the first acquisition signal of hot-swap operation, so as to control the substation double bus tie equivalent model to enter the first acquisition stage; The first line three-phase current is obtained based on the line current meter, and the first bus three-phase current is obtained based on the bus tie current meter. Acquire the second acquisition signal for hot-swap operation, and control the target switch to be in a closed state based on the second acquisition signal for hot-swap operation; The second line three-phase current is obtained based on the line current meter, and the second bus three-phase current is obtained based on the bus tie current meter. The change in the three-phase current of the first busbar is obtained based on the three-phase current of the first busbar and the three-phase current of the second busbar. The change in the three-phase current of the first line is obtained based on the three-phase current of the first line and the three-phase current of the second line. The changes in the three-phase current of the first busbar and the changes in the three-phase current of the first line are used as the first three-phase current change data.

[0040] Optionally, step S22 includes: Acquire the third acquisition signal of the hot switch operation, and control the original disconnector to be in the open state based on the third acquisition signal of the hot switch operation, so as to control the substation double bus tie equivalent model to enter the second acquisition stage; The three-phase current of the third line is obtained based on the line current meter, and the three-phase current of the third bus is obtained based on the bus tie current meter. The change in the three-phase current of the second busbar is obtained based on the three-phase current of the third busbar and the three-phase current of the second busbar. The change in the three-phase current of the second line is obtained based on the three-phase current of the third line and the three-phase current of the second line. The change in the three-phase current of the second busbar and the change in the three-phase current of the second line are used as the data for the change in the second three-phase current.

[0041] In practice, when a single phase of the disconnector fails to close properly, the three-phase load becomes unbalanced due to the large arc resistance of that phase, resulting in a large zero-sequence current at the disconnector.

[0042] In Phase Two, the two disconnectors QS12 and QS11 are interconnected, forming a loop with the bus tie branch. At this point, the zero-sequence current generated by the incomplete closing of disconnector QS11 will only flow within the loop and will not flow out. The bus tie current can be expressed by Kirchhoff's current law as follows: In the formula: Indicates the current on the bus tie. This indicates the current flowing through the disconnect switch QS12.

[0043] Since zero-sequence current flows in the loop, there will be zero-sequence current on the disconnector QS12. Therefore, there is a large zero-sequence current on the bus tie. The current on the line CT can be expressed by Kirchhoff's current law as follows: In the formula: This indicates the current in branch L6 of the line. This represents the current flowing through disconnector QS11. In stage two, the zero-sequence currents on the two disconnectors cancel each other out, therefore ultimately... With three phases in balance, the zero-sequence current can be ignored.

[0044] In stage three, since the two disconnectors QS12 and QS11 are not interconnected, zero-sequence current can flow out. Branch L6 directly transmits power to the first busbar via disconnector QS11. The bus tie current expression in this stage is the same as in stage two. Since disconnector QS12 is open at this time, there is no current flowing through it, therefore the current in the bus tie is also close to zero. The current in branch L6 is equal to the current flowing through disconnector QS11, which can be expressed as follows: In the formula: This indicates the current flowing through the disconnect switch QS11; This indicates the current in branch L6 of the line.

[0045] From the above formula, it can be seen that the current of CT2 on the line is approximately equal to the current of the disconnector QS11. Therefore, the zero-sequence current detected by the current transformer on branch L6 is approximately equal to the zero-sequence current on disconnector QS11. The zero-sequence current waveforms at the detection point during the incomplete closing are as follows: Figure 3 As shown, the horizontal axis represents time (time / s), and the vertical axis represents the corresponding current data. / A, the red dashed line indicates that the circuit breaker is being tripped at this point.

[0046] In phases two and three, when an asymmetrical grounding fault occurs, taking a fault on the first busbar as an example (e.g.) Figure 2 Analysis is performed on the circuit marked with a green circle. At this time, both line L6 and the bus tie branch are zero-sequence current paths. Therefore, the current transformers at both locations can detect zero-sequence current in both stages. The zero-sequence current waveforms at the detection points in the two stages when a single-phase ground fault occurs are as follows: Figure 4 As shown, the red dashed line indicates that the circuit breaker begins to trip at this point.

[0047] Optionally, step S24 includes: The first three-phase current change data includes the change in the three-phase current of the first bus and the change in the three-phase current of the first line, and the first zero-sequence current data includes the change in the zero-sequence current of the first bus and the change in the zero-sequence current of the first line. The first bus index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the first bus. The first line index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the first line. The second three-phase current change data includes the change in the three-phase current of the second bus and the change in the three-phase current of the second line; the second zero-sequence current data includes the change in the zero-sequence current of the second bus and the change in the zero-sequence current of the second line. The second bus index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the second bus. The second line index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the second line. The first busbar state variable is obtained by judging the state based on the first busbar index and the preset elastic threshold; the second busbar state variable is obtained by judging the state based on the second busbar index and the preset elastic threshold. Based on the first line indicator and the preset elastic threshold, a state judgment is made to obtain the first line state variable; based on the second line indicator and the preset elastic threshold, a state judgment is made to obtain the second line state variable.

[0048] In the specific implementation process, as the above analysis shows, zero-sequence current is almost non-existent during normal operation. However, when the disconnector fails to close properly or an asymmetrical grounding fault occurs in the system, the three-phase current exhibits unbalanced characteristics, thereby triggering abnormal zero-sequence current components at the corresponding locations. This embodiment utilizes the current data from various measuring points before and after opening the disconnector on the original busbar side to construct a zero-sequence normalization index, further enhancing the adaptability and stability of this criterion under different operating conditions. Specifically, firstly, the effective values ​​of the three-phase currents at the corresponding measuring points (at the bus tie circuit breaker and the disconnector line circuit breaker) are collected instantaneously before and after the closing or opening operation (including closing the target disconnector and opening the disconnector on the original busbar side). These values ​​include the three-phase currents of the first line, the first busbar, the second line, the second busbar, the third line, and the third busbar. The changes in each phase of the three-phase current before and after opening the disconnector on the original busbar side are then calculated. , and (Including the changes in the three-phase current of the first busbar, the changes in the three-phase current of the first line, the changes in the three-phase current of the second busbar, and the changes in the three-phase current of the second line, the calculation process is the same), the calculation process is as follows: In the formula: This indicates the A-phase current before the operation of closing or opening the circuit breaker. This indicates the B-phase current before the operation of closing or opening the circuit breaker. This indicates the C-phase current before the operation of closing or opening the circuit breaker. This indicates the A-phase current after the operation of closing or opening the circuit breaker. This indicates the B-phase current after the operation of closing or opening the circuit breaker. This indicates the C-phase current after the circuit is closed or opened.

[0049] Next, calculate the corresponding zero-sequence current changes (including the zero-sequence current changes of the first bus, the first line, the second bus, and the second line, using the same calculation method). The calculation process is as follows: In the formula: It represents the change in zero-sequence current.

[0050] Considering that using the zero-sequence current amplitude alone for judgment is easily affected by factors such as system load and power supply structure, and may lead to misjudgment, this embodiment further constructs a normalized zero-sequence current index. (Including the first bus index, the second bus index, the first line index, and the second line index, all of which undergo the same normalization calculation process), the normalization calculation process is as follows: The logic behind this indicator is as follows: by normalizing the ratio of the zero-sequence current change to the maximum value among the three-phase current changes, the criterion focuses on the current imbalance itself, rather than the total magnitude. At the same time, considering the differences in manufacturing processes of three-phase disconnectors, the following empirical threshold (i.e., the preset elastic threshold) is set: When performing state judgment, when If the above conditions are met, the zero-sequence current at that location is considered to be outside the normal range, and further judgment of the abnormality type is required; otherwise, it is in normal operating condition.

[0051] Optionally, step S25 includes: Perform a logical AND operation on the first bus state variable and the first line state variable to obtain the first state variable; The second state variable is obtained by performing an XOR operation on the first bus state variable and the first line state variable. A third state variable is obtained by performing a logical AND operation on the second bus state variable and the second line state variable. The fourth state variable is obtained by performing an XOR operation on the second bus state variable and the second line state variable. When the first matching condition is met based on the first state variable and the third state variable, the fault identification result output by the preset fault matching library is: there is an asymmetrical grounding fault. When the second matching condition is met based on the first and third state variables, the following further judgment action is executed: When the third matching condition is met based on the second and fourth state variables, the fault identification result output by the preset fault matching library is: there is a disconnector that is not fully closed; When the fourth matching condition is met based on the second and fourth state variables, the fault identification result output by the preset fault matching library is: the disconnector is closed in place.

[0052] In the specific implementation process, in order to accurately identify the three situations during the hot busbar switching process—closing in place, closing in place, and asymmetrical grounding fault—this embodiment establishes an executable criterion based on the aforementioned zero-sequence normalization criterion by using a preset fault matching library to comprehensively determine the over-limit situation in two stages at the same measuring point. A preset elastic threshold of 0.15 is set, and the presence or absence of an over-limit phenomenon in two stages at a certain measuring point is used as the status identifier of that measuring point. Furthermore, the classification and determination of the three operating states are achieved through the combination relationship of the states of two measuring points. The specific criterion for identifying the disconnector closing in place and the fault state is as follows: Define state variables. , , , The following output conditions must be met: In the formula: This represents the state variables of the first busbar of the bus tie circuit breaker in stage two. This represents the second busbar state variable of the bus tie circuit breaker in stage three. This represents the first line state variable of the line circuit breaker in stage two. This represents the second line state variable of the line circuit breaker in stage three.

[0053] Based on this, define the comprehensive state variable. , , , Satisfy the following formula: In the formula: This represents the first state variable in phase two. This represents the third state variable in phase two. This represents the second state variable in phase three. This represents the fourth state variable in phase three.

[0054] The criteria for determining the fault identification results based on the preset fault matching library are as follows: like If the first matching condition is met, the fault identification result is output as an asymmetrical grounding fault. like If the second matching condition is met, then further evaluation is required: like If the third matching condition is met, the fault identification result will be output as the disconnector is closed in place. like If the fourth matching condition is met, the fault identification result will be output as "the disconnector is not properly closed".

[0055] Optionally, when the output shows a fault identification result indicating an asymmetrical grounding fault, a fault clearing action is triggered.

[0056] Optionally, when the output shows a fault identification result indicating that the disconnector is not fully closed, the relevant protection action is triggered to lock out the circuit breaker.

[0057] In the specific implementation process, when neither of the two stages of each measuring point exceeds the threshold, it is determined that the circuit breaker is closed in place; when either stage of a measuring point exceeds the threshold, it is determined that the disconnector is not closed in place, triggering the relevant protection action of blocking and performing the relevant protection action, and issuing an alarm at the same time; when both stages of each measuring point exceed the threshold, it is determined that there is an asymmetrical grounding fault, and the fault is cleared immediately.

[0058] In summary, to address the issue of incomplete disconnection of disconnectors during remote control hot busbar switching operations, this embodiment proposes a method for identifying incomplete disconnection of hot busbar disconnectors based on the difference in zero-sequence current characteristics. This method accurately identifies incomplete disconnection and asymmetrical grounding faults, effectively avoiding misjudgments and ensuring the safe and stable operation of the power system. By utilizing existing bus tie circuit breakers and line CT current measurement points, there is no need to add current transformers at the disconnectors, reducing modification costs and simplifying engineering implementation, thus demonstrating good engineering feasibility.

[0059] In practical implementation, this embodiment identifies incomplete closing of the hot busbar disconnector based on the difference in zero-sequence current characteristics. The specific judgment process is as follows: Figure 5 As shown, it includes: start; Construct an equivalent model of a substation dual busbar connection based on actual substation data; The hot busbar switching process is performed based on the equivalent model of the substation with dual busbars. Determine whether the target disconnector is closed. If not, return to step S2; if yes, proceed to step S4. Acquire the first and second phase current variation data; Determine whether the bus tie circuit breaker is open. If not, return to step S4; if yes, proceed to step S6. Calculate the change in zero-sequence current for each line; Calculate the indicators and make threshold judgments based on preset elastic thresholds; Calculate the state variables and the corresponding integrated state vector; conform to The output fault identification result is that an asymmetrical grounding fault has occurred; conform to Continue the judgment action: conform to The fault identification result is that the disconnector is closed in place; conform to The output fault identification result is that the disconnector is not fully closed; Finish.

[0060] In the above process, the decision to start the hot busbar switching operation is made by determining whether the target disconnector is closed, and the decision to end the second acquisition stage is made by determining whether the bus tie circuit breaker is open. Based on this, a first acquisition signal for the hot busbar switching operation is generated before entering the second stage, and a second acquisition signal for the hot busbar switching operation is generated before entering the third stage, in order to obtain the first three-phase current change data and the second three-phase current change data.

[0061] This embodiment provides a fault identification system based on zero-sequence current, used to implement the aforementioned fault identification method based on zero-sequence current, including: The model building module is used to build an equivalent model of a substation with dual busbars based on actual substation data. The fault identification module is used to perform hot-swap operation fault identification actions based on the equivalent model of the substation's double busbars: controlling the equivalent model of the substation's double busbars to enter the first acquisition stage to acquire first three-phase current change data; controlling the equivalent model of the substation's double busbars to enter the second acquisition stage to acquire second three-phase current change data; acquiring first zero-sequence current data based on the first three-phase current change data, and acquiring second zero-sequence current data based on the second three-phase current change data; acquiring first busbar state variables and first line state variables based on the first three-phase current change data, first zero-sequence current data, and a preset elastic threshold; acquiring second busbar state variables and second line state variables based on the second three-phase current change data, second zero-sequence current data, and the preset elastic threshold; and acquiring the output fault identification result based on the matching of the first busbar state variables, first line state variables, second busbar state variables, and second line state variables based on a preset fault matching library.

[0062] The implementation of this embodiment has the following beneficial effects: By collecting three-phase current changes in stages and calculating normalized indices, interference from system load and operating mode is eliminated, ensuring that current characteristics can accurately reflect operational anomalies and faults; by comparing data from two acquisition stages and designing a logic operation matching mechanism, effective differentiation between incomplete closing and asymmetrical grounding faults is achieved, solving the problems of misjudgment and omission in traditional methods; after fault identification, linked handling actions are taken to avoid the risk of protection malfunction and equipment damage, improving the safety of hot busbar operation and the reliability of power grid operation; engineering feasibility: at the same time, when constructing the equivalent model, it is based on the existing current device, without the need to add equipment, which facilitates actual deployment and reduces the cost of modification and implementation difficulty.

[0063] In summary, this embodiment first constructs an equivalent model of a double busbar including the characteristics of the disconnector arc, dividing the hot busbar switching operation into three stages for the acquisition of three-phase current data in the first and second acquisition stages. Next, three-phase currents are acquired at the bus tie circuit breaker and the switching line circuit breaker in stages two and three, respectively. The zero-sequence current change is calculated, a normalized index is constructed, and threshold comparisons are performed. Finally, operating condition judgment is achieved based on the exceedance of the indexes in each stage: when the indexes at each measuring point in both stages do not exceed the threshold, the disconnector is determined to be closed in place; when the threshold is exceeded in either stage, the disconnector is determined to be not closed in place, and relevant protections are blocked; when the thresholds are exceeded in both stages, an asymmetrical grounding fault is determined, and the fault is promptly cleared. This achieves rapid and accurate identification of disconnector not closing in place and asymmetrical grounding faults, avoiding the occurrence of busbar protection malfunctions or even serious accidents such as disconnector operation under load, improving the safety and reliability of hot busbar switching operations, and providing technical support for improving the intelligent diagnostic capabilities and control safety level of substation systems.

[0064] Based on the above embodiment of a fault identification method based on zero-sequence current, this embodiment also provides a storage medium, including: a stored computer program, wherein, when the computer program is running, it controls the device where the storage medium is located to execute the above-described fault identification method based on zero-sequence current.

[0065] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0066] Based on the above embodiment of a fault identification method based on zero-sequence current, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements a fault identification method based on zero-sequence current according to any embodiment of the present invention.

[0067] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0068] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0069] The modules / units integrated in the device / terminal equipment, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0070] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A fault identification method based on zero-sequence current, characterized in that, include: Construct an equivalent model of a substation dual busbar connection based on actual substation data; Based on the equivalent model of the substation's dual busbar connection, perform hot-swap operation fault identification actions: The equivalent model of the substation with dual busbars is controlled to enter the first acquisition stage to acquire the first three-phase current change data. The equivalent model of the substation with dual busbars is controlled to enter the second acquisition stage to acquire the second three-phase current change data. First zero-sequence current data is obtained based on the first three-phase current change data, and second zero-sequence current data is obtained based on the second three-phase current change data. The first bus state variable and the first line state variable are obtained based on the first three-phase current change data, the first zero-sequence current data and the preset elastic threshold. The second bus state variable and the second line state variable are obtained based on the second three-phase current change data, the second zero-sequence current data and the preset elastic threshold. The output fault identification result is obtained by matching the first bus status variable, the first line status variable, the second bus status variable, and the second line status variable based on the preset fault matching library.

2. The fault identification method based on zero-sequence current as described in claim 1, characterized in that, The construction of the equivalent model of the dual busbar connection of the substation based on actual substation data includes: An equivalent model of a substation with dual busbars is constructed based on actual substation data and pre-set disconnector arc model. The equivalent model of the substation with dual busbars includes the first busbar, the second busbar, the busbar branch, and the disconnector branch; The first busbar and the second busbar are electrically connected through the bus tie branch; The bus tie branch includes a bus tie circuit breaker and a bus tie current transformer connected in series. The disconnector branch includes a primary disconnector, a target disconnector, and a line current transformer, wherein: the first end of the primary disconnector is electrically connected to the first busbar, the first end of the target disconnector is electrically connected to the second busbar, the second end of the primary disconnector is electrically connected to the second end of the target disconnector, the second end of the target disconnector is electrically connected to the first end of the line current transformer, and the second end of the line current transformer serves as the load output end of the disconnector branch.

3. The fault identification method based on zero-sequence current as described in claim 2, characterized in that, The control of the substation's dual-busbar equivalent model to enter the first acquisition stage, acquiring the first three-phase current change data, including: Acquire the first acquisition signal of hot-swap operation, and control the bus tie disconnect device to be in a closed state based on the first acquisition signal of hot-swap operation, so as to control the substation double bus tie equivalent model to enter the first acquisition stage; The first line three-phase current is obtained based on the line current meter, and the first bus three-phase current is obtained based on the bus tie current meter. Acquire the second acquisition signal for hot-swap operation, and control the target switch to be in a closed state based on the second acquisition signal for hot-swap operation; The second line three-phase current is obtained based on the line current meter, and the second bus three-phase current is obtained based on the bus tie current meter. The change in the three-phase current of the first busbar is obtained based on the three-phase current of the first busbar and the three-phase current of the second busbar. The change in the three-phase current of the first line is obtained based on the three-phase current of the first line and the three-phase current of the second line. The changes in the three-phase current of the first busbar and the changes in the three-phase current of the first line are used as the first three-phase current change data.

4. The fault identification method based on zero-sequence current as described in claim 3, characterized in that, The control of the substation's dual-busbar equivalent model to enter the second acquisition stage, acquiring the second three-phase current change data, including: Acquire the third acquisition signal of the hot switch operation, and control the original disconnector to be in the open state based on the third acquisition signal of the hot switch operation, so as to control the substation double bus tie equivalent model to enter the second acquisition stage; The three-phase current of the third line is obtained based on the line current meter, and the three-phase current of the third bus is obtained based on the bus tie current meter. The change in the three-phase current of the second busbar is obtained based on the three-phase current of the third busbar and the three-phase current of the second busbar. The change in the three-phase current of the second line is obtained based on the three-phase current of the third line and the three-phase current of the second line. The change in the three-phase current of the second busbar and the change in the three-phase current of the second line are used as the data for the change in the second three-phase current.

5. The fault identification method based on zero-sequence current as described in claim 1, characterized in that, The step of obtaining the first bus state variable and the first line state variable based on the first three-phase current change data, the first zero-sequence current data, and the preset elastic threshold, and obtaining the second bus state variable and the second line state variable based on the second three-phase current change data, the second zero-sequence current data, and the preset elastic threshold, includes: The first three-phase current change data includes the change in the three-phase current of the first bus and the change in the three-phase current of the first line, and the first zero-sequence current data includes the change in the zero-sequence current of the first bus and the change in the zero-sequence current of the first line. The first bus index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the first bus. The first line index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the first line. The second three-phase current change data includes the change in the three-phase current of the second bus and the change in the three-phase current of the second line; the second zero-sequence current data includes the change in the zero-sequence current of the second bus and the change in the zero-sequence current of the second line. The second bus index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the second bus. The second line index is obtained by normalizing the changes in the three-phase current and the zero-sequence current of the second line. The first busbar state variable is obtained by judging the state based on the first busbar index and the preset elastic threshold; the second busbar state variable is obtained by judging the state based on the second busbar index and the preset elastic threshold. Based on the first line indicator and the preset elastic threshold, a state judgment is made to obtain the first line state variable; based on the second line indicator and the preset elastic threshold, a state judgment is made to obtain the second line state variable.

6. The fault identification method based on zero-sequence current as described in claim 1, characterized in that, The output fault identification result, obtained by matching the first bus status variable, the first line status variable, the second bus status variable, and the second line status variable based on a preset fault matching library, includes: The first state variable is obtained by performing a logical AND operation based on the first bus state variable and the first line state variable. The second state variable is obtained by performing an XOR operation on the first bus state variable and the first line state variable. A third state variable is obtained by performing a logical AND operation on the second bus state variable and the second line state variable. The fourth state variable is obtained by performing an XOR operation on the second bus state variable and the second line state variable. When the first matching condition is met based on the first state variable and the third state variable, the fault identification result output by the preset fault matching library is: there is an asymmetrical grounding fault. When the second matching condition is met based on the first and third state variables, the following further judgment action is executed: When the third matching condition is met based on the second and fourth state variables, the fault identification result output by the preset fault matching library is: there is a disconnector that is not fully closed; When the fourth matching condition is met based on the second and fourth state variables, the fault identification result output by the preset fault matching library is: the disconnector is closed in place.

7. The fault identification method based on zero-sequence current as described in claim 6, characterized in that, include: When the output shows a fault identification result indicating an asymmetrical grounding fault, a fault clearing action is triggered.

8. The fault identification method based on zero-sequence current as described in claim 6, characterized in that, include: When the output shows a fault identification result indicating that the disconnector is not closing properly, the relevant protection action is triggered to lock out the circuit breaker.

9. A fault identification system based on zero-sequence current, characterized in that, A method for implementing a fault identification method based on zero-sequence current as described in any one of claims 1 to 8, comprising: The model building module is used to build an equivalent model of a substation with dual busbars based on actual substation data. The fault identification module is used to perform hot-swap operation fault identification actions based on the equivalent model of the substation's double busbars: controlling the equivalent model of the substation's double busbars to enter the first acquisition stage to acquire first three-phase current change data; controlling the equivalent model of the substation's double busbars to enter the second acquisition stage to acquire second three-phase current change data; acquiring first zero-sequence current data based on the first three-phase current change data, and acquiring second zero-sequence current data based on the second three-phase current change data; acquiring first busbar state variables and first line state variables based on the first three-phase current change data, first zero-sequence current data, and a preset elastic threshold; acquiring second busbar state variables and second line state variables based on the second three-phase current change data, second zero-sequence current data, and the preset elastic threshold; and acquiring the output fault identification result based on the matching of the first busbar state variables, first line state variables, second busbar state variables, and second line state variables based on a preset fault matching library.

10. A storage medium, characterized in that, include: A stored computer program, wherein, when the computer program is executed, the device containing the storage medium is controlled to perform a fault identification method based on zero-sequence current as described in any one of claims 1-8.

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