3 / 2 wiring switch station area protection method and device based on fault component lissajous curve and medium

Abstract

This application provides a method, device, and medium for station area protection of 3 / 2-connected switchgear based on fault component Lissajous curves, relating to the field of relay protection technology. The method includes: acquiring the fault components of the entire station current; identifying faults within the station based on the Lissajous curve characteristics of the sum of the upper and lower incoming and outgoing line current fault components; determining whether the fault area is the upper or lower half based on the Lissajous curve characteristics of the incoming and outgoing line current fault components and the intermediate circuit breaker current fault components; identifying busbar faults or T-zone faults based on the Lissajous curve characteristics of the incoming and outgoing line currents, intermediate circuit breaker currents, and side circuit breaker current fault components; and locating the fault string based on the slope characteristics of the Lissajous curves of the intermediate circuit breaker current fault components in the case of a T-zone fault. This application utilizes multi-dimensional Lissajous curve slope characteristics to accurately identify faults within the station, distinguish fault areas, identify busbar or T-zone faults, and locate fault strings in the event of a CT disconnection.

Description

Technical Field

[0001] This application relates to the field of relay protection technology, and in particular to a method, device and medium for the protection of 3 / 2 wire connection switch station area based on fault component Lissajous curves. Background Technology

[0002] As the core node for power conversion, distribution, and control in a power system, the safe and stable operation of a switchyard directly determines the reliability of the entire power supply. The switchyard busbar is one of the most critical components in a power system. If a fault occurs on the busbar, the busbar protection system must quickly disconnect all components connected to it. If the busbar protection system misjudges the situation, it can lead to power loss or compromised equipment safety, or even widespread power outages and system instability. While a short-circuit fault in a current transformer (CT) does not affect the normal power transmission and distribution, a lack of information can cause relay protection systems to malfunction or fail to operate, potentially causing significant damage to the power system.

[0003] Traditional protection configurations cannot mitigate the risk of incorrect protection operation during combined faults such as CT line disconnection. Only station-wide protection utilizing station-wide information can address these issues, enabling rapid and reliable fault clearing through multi-point information from the switching station. Furthermore, it considers the impact on the system after fault clearing and employs appropriate control measures to minimize this impact. Therefore, proposing a scientifically sound and reasonable technical method to address the problems existing in switching stations is imperative. Summary of the Invention

[0004] This application provides a method, device, and medium for station area protection of 3 / 2-connected switchgear based on fault component Lissajous curves. It constructs Lissajous curves using multi-point current fault component information of the entire station, and achieves accurate identification of faults within the station, rapid division of fault areas, reliable differentiation of busbar and T-zone faults, and precise location of fault strings under any CT disconnection condition. This solves the problem of incorrect operation caused by information loss in traditional protection configurations, and improves the safety and power supply reliability of switchgear operation.

[0005] Firstly, this application provides a method for station area protection of 3 / 2-connected switchgear based on fault component Lissajous curves, the method comprising: Obtain the current fault components of each circuit breaker and incoming / outgoing line in the substation; based on the Lissajous curve characteristics of the upper and lower incoming / outgoing line current fault components flowing into the substation, determine whether a fault has occurred in the substation. After identifying the fault as an internal fault, based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents and the fault components of the intermediate circuit breaker currents, the fault area is determined to be either the upper or lower half of the switching station. After identifying the fault area, based on the Lissajous curve characteristics of the fault components of incoming and outgoing line current, intermediate circuit breaker current, and side circuit breaker current, the fault type is determined to be either a bus fault or a T-zone fault. When a fault is identified as a T-zone fault, the fault string is located based on the slope characteristics of the Lissajous curve of the fault component of the current in the intermediate circuit breaker of each string.

[0006] In one possible design, the presence or absence of an in-station fault is determined based on the Lissajous curve characteristics of the fault components of the upper and lower incoming / outgoing line currents flowing into the station, including: When the positive direction of the fault component current of the upper and lower incoming and outgoing lines is flowing into the switch station, the Lissajous curves of the sum of the fault components of the upper and lower incoming and outgoing line currents are obtained with a time window of a set length. The judgment is made based on the Lissajous curves. When the first criterion and the second criterion are satisfied at the same time, it is determined to be an in-station fault. The first criterion is: (1) The second criterion is: (2) In the formula: , These are the fault component phase currents flowing into the switchyard from the upper and lower incoming / outgoing lines, respectively.

[0007] In one possible design, after identifying a fault as within the substation, based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents and the fault components of the intermediate circuit breaker current, the fault area is determined to be either the upper or lower half of the switching station, including: When the positive direction of the fault component current flowing through the intermediate circuit breaker is from the lower busbar to the upper busbar, and the switchyard is divided into upper and lower parts with the intermediate circuit breaker being the overlapping area of ​​the two parts, after identifying the fault within the station, the fault is determined based on the Lissajous curve of the sum of the fault components of the upper incoming and outgoing line currents and the sum of the fault components of the intermediate circuit breaker current. When the third criterion is met, the fault area is determined to be the upper half of the switchyard; wherein, the third criterion is: (3) In the formula: The fault component phase current flowing through the intermediate circuit breaker; After identifying a fault within the station, a Lissajous curve is used to determine the fault area based on the sum of the fault components of the incoming and outgoing line currents and the sum of the fault components of the intermediate circuit breaker current. When the fourth criterion is met, the fault area is determined to be the lower half of the switching station. The fourth criterion is: (4).

[0008] In one possible design, after identifying the fault area, the fault type is determined to be either a bus fault or a T-zone fault based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents, the intermediate circuit breaker current fault components, and the side circuit breaker current fault components, including: When the positive direction of the fault current component of the upper and lower circuit breakers flows out from the upper and lower busbars, after the fault area is determined, the Lissajous curve is used to determine the fault area. When the fifth criterion is met, it is determined to be a busbar fault; when the sixth criterion is met, it is determined to be a T-zone fault. The fifth criterion is: (5) The sixth criterion is: (6) In the formula: , These are the fault component phase currents flowing into the switchyard from the upper and lower incoming / outgoing lines, respectively. The fault component phase current flowing through the intermediate circuit breaker, , These are the differential current fault components of the upper busbar and the lower busbar, respectively.

[0009] In one possible design, when a fault is identified as a T-zone fault, the fault string is located based on the slope characteristics of the Lissajous curves of the fault components of the intermediate circuit breakers in each string, including: After determining that the fault is in zone T, the fault is determined based on the Lissajous curve of the fault current component of each string and the sum of the fault current components of each string's intermediate circuit breaker. The string with the slope closest to 1 is then identified as the fault string.

[0010] In one possible design, the method further includes handling for broken incoming and outgoing CT wires, specifically including: When a current transformer (CT) disconnects in an incoming or outgoing line, the fault component of the incoming or outgoing line current is set to zero, and the fault identification within the station and the fault area are continued. If the incoming / outgoing line CT disconnection is accompanied by a bus fault, when determining the fault type, the Lissajous curve based on the sum of the fault components of the incoming / outgoing line current and the intermediate circuit breaker current and the sum of the fault components of the upper side circuit breaker current falls into the second or fourth quadrant, and there is no side circuit breaker disconnection, then it is still determined to be a bus fault. If the incoming / outgoing line CT disconnection is accompanied by a fault in zone T, when determining the fault type, if the Lissajous curve of the sum of the fault components of the upper incoming / outgoing line current and the intermediate circuit breaker current and the upper circuit breaker current is located on the coordinate axis, it is determined to be a fault in zone T, and fault string location is performed.

[0011] In one possible design, the method further includes handling for intermediate circuit breaker CT disconnection, specifically including: When a CT disconnection is detected at an intermediate circuit breaker in a certain string, a substitute current is used to replace the fault component of the intermediate circuit breaker current in the disconnected string. The substitute current is calculated based on the incoming and outgoing currents of the column where the disconnected string is located and the current of the circuit breaker below it, so that subsequent fault identification is not affected.

[0012] In one possible design, the method further includes handling for disconnection of the side circuit breaker CT, specifically including: When a circuit breaker CT disconnects, the current fault component at the circuit breaker in that series is set to zero, and the identification of faults and fault areas within the station continues. If a circuit breaker current transformer (CT) disconnection is accompanied by a busbar fault, when determining the fault type, based on the Lissajous curve of the sum of the incoming and outgoing currents and the fault components of the intermediate circuit breaker currents and the sum of the fault components of the upper side circuit breaker currents falling into the second or fourth quadrant, the string with the slope closest to 1 is selected as the suspected string based on the Lissajous curve of the fault components of the intermediate circuit breakers in each string and the sum of the fault components of the intermediate circuit breakers in each string. If the disconnected string is not a suspected string, it is directly determined to be a busbar fault. If the disconnected string is a suspected string, the side circuit breaker of that string is disconnected, and the fault is determined based on the fault components of the currents of the remaining branches. If the busbar fault criterion is met, it is determined to be a busbar fault. If the circuit breaker CT disconnection is accompanied by a fault in the T-zone of the disconnected string, when determining the fault type, the Lissajous curve of the sum of the fault components of the upper incoming and outgoing current and the intermediate circuit breaker current and the upper side circuit breaker current falls into the second or fourth quadrant. The disconnected string is the suspected string with the slope closest to 1. After disconnecting the circuit breaker of the string, the fault is determined based on the fault components of the current in the other branches. If the bus fault criterion is not met, it is determined to be a fault in the T-zone of the string. If the circuit breaker CT disconnection is accompanied by a non-disconnection series fault in zone T, when determining the fault type, if the Lissajous curve of the sum of the fault components of the upper incoming and outgoing current and the intermediate circuit breaker current and the upper circuit breaker current falls into the first quadrant or the third quadrant, it is determined to be a fault in zone T, and fault series location is performed.

[0013] Secondly, this application provides a 3 / 2 wiring switch station area protection device based on fault component Lissajous curves, the device comprising: The station fault detection module is configured to acquire the current fault components of each circuit breaker and incoming and outgoing line in the switch station; and determine whether a station fault has occurred based on the Lissajous curve characteristics of the upper and lower incoming and outgoing line current fault components flowing into the station. The fault area identification module is configured to, after identifying a fault as an in-station fault, determine whether the fault area is the upper or lower half of the switch station based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents and the fault components of the intermediate circuit breaker currents. The fault type discrimination module is configured to, after identifying the fault area, determine the fault type as bus fault or T-zone fault based on the Lissajous curve characteristics of the incoming and outgoing line current fault components, intermediate circuit breaker current fault components and side circuit breaker current fault components. The fault string location module is configured to locate the fault string based on the slope characteristics of the Lissajous curve of the fault component of the current of the intermediate circuit breaker in each string when the fault is identified as a T-zone fault.

[0014] Thirdly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions. When a processor executes the computer-executable instructions, it implements the 3 / 2 wiring switch station domain protection method described in the first aspect and various possible designs of the first aspect.

[0015] The method, device, and medium for 3 / 2 wire connection switchgear station protection based on fault component Lissajous curves provided in this application have at least the following beneficial effects: This application utilizes the station-wide protection device of the switching station to collect current data of all circuit breakers and incoming / outgoing lines in the station. Based on the instantaneous value of the fault component current, a Lissajous curve is constructed to effectively identify faults within the station. When any CT disconnects and is accompanied by a fault within the station while collecting current data of all circuit breakers and incoming / outgoing lines, the application can identify faulty components in the busbars and T-zones within the switching station. Unlike previous methods that only identified faults in a single bay, the method of this application is scientific and reasonable, simple to calculate, easy to implement, accurate in identification, highly applicable, highly sensitive, and has a certain degree of fault tolerance. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0017] Figure 1 A basic flowchart of a fault discrimination method for a 3 / 2 wiring switch station area protection method based on fault component Lissajous curves provided in Embodiment 1 of this application; Figure 2 A specific switchyard system diagram illustrating the application of a 3 / 2 wiring switchyard regional protection method based on fault component Lissajous curves provided in Embodiment 1 of this application; Figure 3The method for protection of a 3 / 2 connection switch station based on fault component Lissajous curves provided in Embodiment 1 of this application includes the waveforms of the sum of the fault components of the upper incoming and outgoing lines and the sum of the fault components of the lower incoming and outgoing lines, the sum of the fault components of the upper incoming and outgoing lines and the sum of the fault components of the upper half of the current flowing into the station and the sum of the fault components of the intermediate circuit breaker, and the sum of the fault components of the six upper incoming and outgoing lines and the six intermediate circuit breaker currents and the six upper circuit breaker currents. Figure 4 The 3 / 2 connection switchyard protection method based on fault component Lissajous curves provided in Embodiment 1 of this application, when a phase A ground fault occurs on the main bus of the switchyard and the current transformers (CTs) in the station are normal, Figure 3 The three sets of waveforms correspond to Lissajous curves within the three time windows; Figure 5 The 3 / 2 connection switch station area protection method based on fault component Lissajous curve provided in Embodiment 1 of this application provides the trip signal diagrams for fault identification, fault area identification, and bus fault identification when an A-phase ground fault occurs on the busbar of the switch station and the CT in the station is normal. Figure 6 The method for station protection of a 3 / 2 connection switchgear based on fault component Lissajous curves provided in Embodiment 2 of this application includes the following waveforms when a phase A ground fault occurs in the upper T zone of the second string of the switchgear and the CTs in the station are normal: the sum of the fault components of the current flowing into the station from the upper incoming and outgoing lines and the sum of the fault components of the current flowing into the station from the lower incoming and outgoing lines; the sum of the fault components of the current flowing into the upper half of the upper incoming and outgoing lines and the sum of the fault components of the current flowing into the upper half of the intermediate circuit breaker; the sum of the fault components of the current flowing into the six strings of upper incoming and outgoing lines and the sum of the fault components of the current flowing into the six strings of intermediate circuit breakers and the sum of the fault components of the current flowing into the six strings of upper circuit breakers; and the sum of the fault components of the current flowing through the intermediate circuit breaker of the fault string and the sum of the fault components of the current flowing through the intermediate circuit breaker of the six strings. Figure 7 The 3 / 2 connection switchyard protection method based on fault component Lissajous curves provided in Embodiment 2 of this application, when a phase A ground fault occurs in zone T of the second string of the switchyard and the CTs in the station are normal, Figure 6 The Lissajous curves corresponding to the four sets of waveforms in the middle; Figure 8 The 3 / 2 connection switch station area protection method based on fault component Lissajous curve provided in Embodiment 2 of this application includes the trip signal diagrams for fault identification, fault area identification, bus fault identification, and fault string discrimination in the T zone when an A-phase ground fault occurs in the T zone of the second string of the switch station and the CT in the station is normal. Figure 9The method for protection of a 3 / 2 connection switch station based on fault component Lissajous curves provided in Embodiment 3 of this application includes the following waveforms when an A-phase ground fault occurs on the upper busbar of the switch station and the first string of incoming and outgoing line CTs is disconnected: the sum of the fault components of the current flowing into the station from the upper incoming and outgoing lines and the sum of the fault components of the current flowing into the station from the lower incoming and outgoing lines; the sum of the fault components of the current flowing into the upper half of the upper incoming and outgoing lines and the sum of the fault components of the current flowing into the upper half of the intermediate circuit breaker; the sum of the currents of the six strings of upper incoming and outgoing lines and the fault components of the current flowing through the intermediate circuit breaker and the sum of the fault components of the current flowing through the upper circuit breaker; and the sum of the fault components of the largest string of currents flowing through the intermediate circuit breaker and the sum of the fault components of the six strings of currents flowing through the intermediate circuit breaker. Figure 10 The 3 / 2 connection switchyard protection method based on fault component Lissajous curves provided in Embodiment 3 of this application is applicable when a phase A ground fault occurs on the busbar of the switchyard and the first series of incoming and outgoing line CTs are disconnected. Figure 9 The Lissajous curves corresponding to the four sets of waveforms in the middle; Figure 11 This application provides a 3 / 2 connection switch station area protection method based on fault component Lissajous curves, which includes trip signal diagrams for fault identification, fault area identification, preliminary bus fault identification, and final fault judgment when an A-phase ground fault occurs on the busbar of the switch station and the first string of incoming and outgoing CTs is disconnected. Figure 12 The method for protection of a 3 / 2 connection switch station based on fault component Lissajous curves provided in Embodiment 4 of this application includes the following waveforms when a phase A ground fault occurs in the T zone of the second string of the switch station and the CT at the intermediate circuit breaker of the second string is disconnected: the sum of the fault components of the current flowing into the station from the upper incoming and outgoing lines and the sum of the fault components of the current flowing into the station from the lower incoming and outgoing lines; the sum of the fault components of the current flowing into the upper half of the upper incoming and outgoing lines and the sum of the fault components of the current flowing into the upper half of the intermediate circuit breaker; the sum of the currents of the six strings of upper incoming and outgoing lines and the fault components of the current flowing through the intermediate circuit breaker and the sum of the fault components of the current flowing through the upper circuit breaker; and the sum of the string with the largest fault component of the current flowing through the intermediate circuit breaker and the sum of the fault components of the current flowing through the intermediate circuit breaker of the six strings. Figure 13 The 3 / 2 connection switchyard protection method based on fault component Lissajous curves provided in Embodiment 4 of this application is applicable when a phase A ground fault occurs in zone T of the second string of the switchyard and the CT is disconnected at the intermediate circuit breaker of the second string. Figure 21 The Lissajous curves corresponding to the four sets of waveforms in the middle; Figure 14The 3 / 2 connection switch station protection method based on fault component Lissajous curve provided in Embodiment 4 of this application provides a trip signal diagram for fault identification, fault area identification, preliminary bus fault identification, and final fault judgment when an A-phase ground fault occurs in the T zone of the second string of the switch station and the CT is disconnected at the intermediate circuit breaker of the second string. Figure 15 The method for protection of a 3 / 2 connection switch station based on fault component Lissajous curves provided in Embodiment 5 of this application includes the following waveforms when a phase A ground fault occurs on the upper busbar of the switch station and the CT at the fourth series circuit breaker is disconnected: the sum of the fault components of the current flowing into the station from the upper incoming and outgoing lines and the sum of the fault components of the current flowing into the station from the lower incoming and outgoing lines; the sum of the fault components of the current flowing into the upper half of the upper incoming and outgoing lines and the sum of the fault components of the current flowing into the upper half of the intermediate circuit breaker; the sum of the currents of the six upper incoming and outgoing lines and the fault components flowing through the intermediate circuit breaker and the sum of the fault components flowing through the upper circuit breaker; and the sum of the fault components of the largest series of currents flowing through the intermediate circuit breaker and the sum of the fault components of the six series of currents flowing through the intermediate circuit breaker. Figure 16 The 3 / 2 connection switchyard protection method based on fault component Lissajous curves provided in Embodiment 5 of this application is applicable when a phase A ground fault occurs on the main bus of the switchyard and the current transformer (CT) at the fourth series circuit breaker is disconnected. Figure 27 The Lissajous curves corresponding to the four sets of waveforms in the middle; Figure 17 The 3 / 2 connection switch station protection method based on fault component Lissajous curve provided in Embodiment 5 of this application includes trip signal diagrams for fault identification, fault area identification, preliminary bus fault identification, and final fault judgment when an A-phase ground fault occurs on the busbar of the switch station and the CT at the fourth string side circuit breaker is disconnected. Figure 18 The method for protection of a 3 / 2 connection switch station based on fault component Lissajous curves provided in Embodiment 5 of this application provides the waveform of the fault component of the upper half current flowing into the incoming and outgoing lines of the remaining five branches after the fourth string side circuit breaker is disconnected, when an A-phase ground fault occurs on the busbar of the switch station and the CT is disconnected at the fourth string side circuit breaker. Figure 19 The Lissajous curve of a 3 / 2 connection switch station provided in Embodiment 5 of this application provides the Lissajous curves corresponding to two waveforms when an A-phase ground fault occurs on the busbar of the switch station and the CT is disconnected at the fourth string side circuit breaker. Figure 20The 3 / 2 connection switch station protection method based on fault component Lissajous curve provided in Embodiment 5 of this application provides the final bus protection trip signal when an A-phase ground fault occurs on the busbar of the switch station and the CT at the fourth string side circuit breaker is disconnected.

[0018] Figure 21 The method for protection of a 3 / 2 connection switch station based on fault component Lissajous curves provided in Embodiment 6 of this application includes the following waveforms when a phase A ground fault occurs in the T zone of the second string of the switch station and the CT at the second string side circuit breaker is disconnected: the sum of the fault components of the current flowing into the station from the upper incoming and outgoing lines and the sum of the fault components of the current flowing into the station from the lower incoming and outgoing lines; the sum of the fault components of the current flowing into the upper half of the upper incoming and outgoing lines and the sum of the fault components of the current flowing into the upper half of the intermediate circuit breaker; the sum of the currents of the six strings of upper incoming and outgoing lines and the fault components of the current flowing through the intermediate circuit breaker and the sum of the fault components of the current flowing through the upper side circuit breaker; and the sum of the string with the largest fault component of the current flowing through the intermediate circuit breaker and the sum of the fault components of the current flowing through the intermediate circuit breaker. Figure 22 The Lissajous curve of a 3 / 2 connection switch station provided in Embodiment 6 of this application provides the Lissajous curves corresponding to four sets of waveforms when an A-phase ground fault occurs in the T zone of the second string of the switch station and the CT is disconnected at the circuit breaker of the second string. Figure 23 The 3 / 2 connection switch station protection method based on fault component Lissajous curve provided in Embodiment 6 of this application provides a trip signal diagram for fault identification, fault area identification, preliminary bus fault identification, and final fault judgment when an A-phase ground fault occurs in the T zone of the second string of the switch station and the CT is disconnected at the circuit breaker of the second string. Figure 24 The method for protection of a 3 / 2 connection switch station based on fault component Lissajous curves provided in Embodiment 6 of this application provides the waveform of the sum of the fault components of the incoming and outgoing currents flowing into the upper half of the branch lines after the second string of the switch station is disconnected and the CT at the second string side circuit breaker is disconnected, when an A-phase ground fault occurs in the T zone of the second string of the switch station and the CT at the second string side circuit breaker is disconnected. Figure 25 The Lissajous curve of a 3 / 2 connection switch station provided in Embodiment 6 of this application provides a Lissajous curve corresponding to two waveforms when an A-phase ground fault occurs in the T zone of the second string of the switch station and the CT is disconnected at the circuit breaker of the second string. Figure 26 The 3 / 2 connection switch station area protection method based on fault component Lissajous curve provided in Embodiment 6 of this application provides the final bus protection trip signal when an A-phase ground fault occurs in the T zone of the second string of the switch station and the CT is disconnected at the circuit breaker of the second string. Figure 27 This is a structural diagram of a 3 / 2 wiring switch station area protection device based on fault component Lissajous curves provided in Embodiment 7 of this application.

[0019] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0020] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0021] The collection, storage, use, processing, transmission, provision, and disclosure of relevant data and information in the technical solution of this application all comply with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0022] It should be noted that in the embodiments of this application, certain software, components, models and other existing solutions in the industry may be mentioned. These should be regarded as exemplary and are only intended to illustrate the feasibility of implementing the technical solution of this application. However, it does not mean that the applicant has used or necessarily used the solution.

[0023] The technical solution of this application and how it solves the above-mentioned technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0024] Example 1: Embodiment 1 of this application provides a method for station area protection of a 3 / 2 wiring switch station based on fault component Lissajous curves, such as... Figure 1 The diagram shown is a basic flowchart of a fault diagnosis method for a 3 / 2 wiring switch station area protection according to an embodiment of this application. The fault diagnosis process is executed according to the following steps: S101: Execute the startup criterion and determine ΔI. Σ1 and ΔI Σ2 Does the Lissajous curve lie in quadrants 1 and 3? Where ΔI... Σ1 The fault component phase current flowing into the switchyard from the incoming and outgoing lines, ΔIΣ2 This refers to the fault component phase current flowing into the switchyard from the incoming and outgoing lines. If the start-up criterion is met, then S102 is executed; otherwise, the process ends.

[0025] S102: Determine ΔI Σ1 and ΔI Σ3 Does the Lissajous curve lie in quadrants 1 and 3? Where ΔI... Σ3 The fault component phase current flows through the intermediate circuit breaker. If yes, execute S103; otherwise, execute S104.

[0026] S103: Determine that a fault has occurred in the upper part of the system, and execute S105.

[0027] S104: Determine that a fault has occurred in the lower half of the system, and execute S115.

[0028] S105: Determine whether the intermediate circuit breaker CT of the m-th string is disconnected. If yes, proceed to S106; otherwise, proceed to S107.

[0029] S106: Use alternative current I m3 =I m5 +I m6 Replace the current sampled by the intermediate circuit breaker in this string. Where I m5 and I m6 The currents of the other two branches corresponding to the node in the string are respectively executed in S107.

[0030] S107: Determine ΔI cd1 and ΔI Σ1 +ΔI Σ3 Is the slope of the Lissajous curve (-1.05 to -0.95)? Where ΔI... cd1 This is the differential current fault component of the upper busbar. If yes, proceed to S108; otherwise, proceed to S109.

[0031] S108: The fault is determined to be on bus 1, and the process ends.

[0032] S109: Define ΔI 3i and ΔI Σ3 The string k whose slope on the Lissajous curve is closest to 1 is a suspicious string. Where ΔI 3i Given the fault component current of the i-th intermediate circuit breaker, execute S110.

[0033] S110: Determine ΔI cd1 and ΔI Σ1 +ΔI Σ3 Does the Lissajous curve lie in quadrants 2 and 4? If yes, execute S112; otherwise, execute S111.

[0034] S111: The fault is determined to be in section T of the k-th string, and the process ends.

[0035] S112: Determine whether the circuit breaker CT above the k-th string is disconnected. If yes, execute S113; otherwise, execute S108.

[0036] S113: Disconnect the circuit breaker above the k-th string and execute S114.

[0037] S114: Determine the ΔI of the remaining 5 strings. Σ1(5) and ΔI Σ3(5) Does the Lissajous curve lie in quadrants 1 and 3? Where ΔI... Σ1(5) The sum of the fault component currents flowing into the upper half of the remaining 5 strings after the k-th string is disconnected, ΔI Σ3(5) This is the sum of the fault component current flowing into the upper half of the circuit breaker after disconnecting the k-th circuit breaker. If yes, execute S108; otherwise, execute S111.

[0038] S115: Determine whether the intermediate circuit breaker CT of the m-th string is disconnected. If yes, proceed to S116; otherwise, proceed to S117.

[0039] S116: Use alternative current I m3 =-I m1 -I m2 Replace the current sampled by the intermediate circuit breaker in this string. Where I m1 and I m2 The currents of the other two branches corresponding to the node in the string are respectively executed in S117.

[0040] S117: Determine ΔI cd2 and ΔI Σ2 -ΔI Σ3 Is the slope of the Lissajous curve (-1.05 to -0.95)? Where ΔI... cd2 This is the differential current fault component of the lower busbar. If yes, execute S118; otherwise, execute S119.

[0041] S118: The fault is determined to be on bus 2, and the process ends.

[0042] S119: Define ΔI 3i and ΔI Σ3 The string k whose slope of the Lissajous curve is closest to 1 is a suspicious string, and S120 is executed.

[0043] S120: Determine ΔI cd2 and ΔI Σ2 -ΔI Σ3 Check if the Lissajous curve is located in quadrants 2 and 4. If yes, execute S122; otherwise, execute S121.

[0044] S121: The fault is determined to be in section T of the k-th string, and the process ends.

[0045] S122: Determine whether the circuit breaker CT below the k-th string is disconnected. If yes, execute S123; otherwise, execute S118.

[0046] S123: Disconnect the circuit breaker below the k-th string and execute S124.

[0047] S124: Determine the ΔI of the remaining 5 strings. Σ2(5) and ΔI Σ3(5) Does the Lissajous curve lie in the 2nd and 4th quadrants? Where ΔI... Σ2(5) The sum of the fault component currents flowing into the lower half of the remaining 5 strings after the k-th string is disconnected, ΔI Σ3(5) This is the sum of the fault component currents flowing into the lower half of the circuit after disconnecting the intermediate circuit breakers of the remaining 5 circuits after the kth circuit. If yes, then execute S118; otherwise, execute S121.

[0048] In this embodiment, the 3 / 2 wiring switch station area protection method is applied to a specific switch station system such as... Figure 2 As shown, the voltage level of this switch station is 500kV, with 6 incoming lines and 6 outgoing lines, totaling 12 T zones. BRKi1 is the circuit breaker for each incoming and outgoing line string, and CTi1 is the current transformer for measuring each BRKi1 string; BRKi6 is the circuit breaker for each incoming and outgoing line string, and CTi6 is the current transformer for measuring each BRKi6 string; BRKi2 is the circuit breaker for each top-side string, and CTi2 is the current transformer for measuring each BRKi2 string; BRKi5 is the circuit breaker for each top-side string, and CTi5 is the current transformer for measuring each BRKi5 string; BRKi3 is the circuit breaker for each intermediate string, and CTi3 is the current transformer for measuring each BRKi3 string; BRK1 and BRK2 are the sectional circuit breakers for the upper and lower busbars, respectively.

[0049] Based on the above working principle, the 3 / 2 connection switch station area protection method takes the case of an A-phase ground fault occurring on the busbar of the switch station and the CT in the station being normal as an example, and includes the following steps S1-S4.

[0050] S1: Obtain the current fault components of each circuit breaker and incoming / outgoing line in the switching station; based on the Lissajous curve characteristics of the upper and lower incoming / outgoing line current fault components flowing into the station, determine whether a fault has occurred in the station.

[0051] This embodiment uses the Lissajous curve position of the sum of the fault components of the current flowing into the station from the upper and lower incoming and outgoing lines and the sum of the fault components of the current flowing into the station from the lower incoming and outgoing lines to determine the fault within the station.

[0052] In one specific embodiment, it is stipulated that the positive direction of the current flowing into the switch station is the same as that of the current flowing into the switch station. When a fault occurs in the switch station, the fault components of the current flowing into the switch station from the upper and lower incoming and outgoing lines are both large in magnitude and flow towards the switch station. When a fault occurs outside the switch station or under normal conditions, the fault components of the two fault components are the same in magnitude and the phase difference is close to 180°. Therefore, the position of the Lissajous curve of the fault components of the current flowing into the switch station from the upper and lower incoming and outgoing lines during a fault can be used to determine the amplitude information of the fault in the switch station, which can be used to enhance the reliability of the phase criterion. The first criterion and the second criterion for judging the fault in the switch station are shown in equations (1) and (2).

[0053] (1) (2) In the formula: , These are the fault component phase currents flowing into the switchyard from the upper and lower incoming / outgoing lines, respectively.

[0054] S2: After determining that the fault is within the station, based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents and the fault components of the intermediate circuit breaker currents, the fault area is determined to be either the upper or lower half of the switching station.

[0055] In this embodiment, after determining the fault within the station, the switch station is divided into upper and lower parts, with the intermediate circuit breaker being the overlapping area of ​​the two parts. The fault area is determined by the position of the Lissajous curve of the sum of the fault components of the current flowing into the switch station from the upper and lower incoming and outgoing lines and the sum of the fault components of the current from the intermediate circuit breaker.

[0056] In one specific embodiment, the positive direction of the current flowing through the intermediate circuit breaker is defined as flowing from the lower busbar to the upper busbar. Utilizing the characteristic that when there is a fault in the upper part of the switchyard, the fault component of the current flowing into the upper part via the upper incoming / outgoing lines and the fault component of the current flowing into the upper part via the intermediate circuit breaker are both large and in the same direction; and when there is a fault in the lower part of the switchyard, the fault component of the current flowing into the lower part via the lower incoming / outgoing lines and the fault component of the current flowing into the lower part via the intermediate circuit breaker are both large and in the same direction, fault area identification within the switchyard is performed. If the Lissajous curves of the sum of the fault components of the current flowing through the upper incoming / outgoing lines and the sum of the fault components of the current flowing through the intermediate circuit breaker are located in quadrants 1 and 3, it is an upper part fault; if the Lissajous curves of the sum of the fault components of the current flowing through the lower incoming / outgoing lines and the sum of the fault components of the current flowing through the intermediate circuit breaker are located in quadrants 2 and 4, it is a lower part fault. The third and fourth criteria used for determining upper and lower part faults are Equations (3) and (4), respectively.

[0057] (3) (4) In the formula: This refers to the fault component phase current flowing through the intermediate circuit breaker.

[0058] S3: After identifying the fault area, based on the Lissajous curve characteristics of the incoming and outgoing line current fault components, intermediate circuit breaker current fault components and side circuit breaker current fault components, the fault type is determined to be either a bus fault or a T-zone fault.

[0059] This embodiment uses the Lissajous curve position of the sum of the current in the six incoming and outgoing lines and the fault component of the current flowing through the intermediate circuit breaker and the sum of the fault component of the current flowing through the upper circuit breaker to make a preliminary judgment on whether it is a bus fault.

[0060] In one specific embodiment, the positive direction of the fault current component of the upper and lower circuit breakers is defined as the current flowing out of the upper and lower busbars. After determining the fault area, when there is a busbar fault, each T-zone satisfies the KCL theorem. Taking a fault on busbar 1 as an example, the sum of the current of the six upper incoming and outgoing lines and the fault current component flowing through the intermediate circuit breaker should be equal in magnitude and in the same direction as the sum of the fault current component flowing through the upper circuit breaker. However, when there is a simple T-zone fault, the fault string T-zone does not satisfy the KCL and the differential current between adjacent buses is 0, thus initially determining whether it is a busbar fault.

[0061] In the next time window for determining the fault area, analyze the Lissajous curves of the sum of the incoming and outgoing line currents and the fault component of the current flowing through the intermediate circuit breaker and the sum of the fault component of the current flowing through the upper circuit breaker. If the slope is -1, it is a bus fault; if it is located on the coordinate axis, it is a T-zone fault; if it is located in quadrants 2 and 4, further judgment is required. The fifth and sixth criteria used for the initial judgment of bus faults and T-zone faults are shown in equations (5) and (6).

[0062] (5) (6) In the formula: , These are the fault component phase currents flowing into the switchyard from the upper and lower incoming / outgoing lines, respectively. The fault component phase current flowing through the intermediate circuit breaker, , These are the differential current fault components of the upper busbar and the lower busbar, respectively.

[0063] S4: When the fault is identified as a T-zone fault, the fault string is located based on the slope characteristics of the Lissajous curve of the fault component of the current of the intermediate circuit breaker in each string.

[0064] This embodiment uses the Lissajous curve of the current fault components of the six intermediate circuit breakers and the sum of the current fault components of the six intermediate circuit breakers to identify the fault string in the T-zone.

[0065] Specifically, based on the characteristic that when a fault occurs in a certain T-zone, the current will flow from the two busbars through the side circuit breaker or the side circuit breaker and the intermediate circuit breaker into the fault point, and only the intermediate circuit breaker of the fault string carries a large current, while the non-faulty string has no direct path to the fault point, we analyze the Lissajous curves of the fault components of the current in the six intermediate circuit breakers and the sum of the fault components of the current in the six intermediate circuit breakers in the next time window. The string with the slope closest to 1 is the faulty string.

[0066] In one specific embodiment, based on the above steps S1-S4, the 3 / 2 wiring switch station area protection method further includes the ability to quickly disconnect and identify faulty components when any CT in the switch station is disconnected, resulting in the loss of collected current information, by combining the station area information. Specifically, this includes: (1) CT line breakage in the inlet and outlet lines When a certain string of incoming and outgoing line CTs is disconnected, the fault component of the current of that string of incoming and outgoing lines is zero. This does not affect the calculation of the fault component of the current of other branch incoming and outgoing lines, and the identification of faults and fault areas in steps 1 and 2 can still be performed. a) Incoming / outgoing line CT disconnection accompanied by busbar fault When the incoming and outgoing line CTs are disconnected and accompanied by a bus fault, the slope of the Lissajous curve of the sum of the incoming and outgoing line currents and the fault component of the current flowing through the intermediate circuit breaker and the sum of the fault component of the current flowing through the side circuit breaker in step 3 is no longer -1, but falls into quadrants 2 and 4. However, since no side circuit breaker disconnection is detected, it can still be correctly identified as a bus fault.

[0067] b) Incoming / outgoing line CT disconnection accompanied by T-zone fault When the incoming and outgoing line CT disconnection is accompanied by a fault in zone T, the Lissajous curve of the sum of the incoming and outgoing line current and the fault component of the current flowing through the intermediate circuit breaker and the sum of the fault component of the current flowing through the side circuit breaker in step 3 is still on the coordinate axis, which can correctly identify it as a fault in zone T and perform fault selection.

[0068] (2) Intermediate circuit breaker CT disconnection Regardless of the operating conditions, as long as a CT is found to be disconnected at a certain intermediate circuit breaker, the substitute current is used directly to replace it, so that subsequent fault identification is not affected in any way.

[0069] (3) The circuit breaker CT is disconnected. When the CT at a certain circuit breaker disconnects, the fault current component at that circuit breaker is zero. This does not affect the calculation of the fault current components of the incoming and outgoing currents of other branches and the intermediate circuit breaker. The identification of faults and fault areas in steps 1 and 2 can still be performed. a) Circuit breaker CT disconnection accompanied by busbar fault When a circuit breaker CT disconnects and a busbar fault occurs, the slope of the Lissajous curve of the sum of the incoming and outgoing currents and the fault component current flowing through the intermediate circuit breaker and the sum of the fault component current flowing through the edge circuit breaker in step 3 is no longer -1, but falls into quadrants 2 and 4. At this time, it is necessary to analyze the Lissajous curves of the fault component currents of the six intermediate circuit breakers and the sum of the fault component currents of the six intermediate circuit breakers. The string with the slope closest to 1 is selected as the suspicious string. If the disconnected string is not a suspicious string, it can be directly judged as a busbar fault. If the disconnected string is a suspicious string, the edge circuit breaker of that string is disconnected. The Lissajous curves of the sum of the fault component currents flowing through the other five intermediate circuit breakers and the sum of the fault component currents flowing through the other five incoming and outgoing lines meet the criteria, and the busbar fault can be identified.

[0070] b) Circuit breaker CT disconnection accompanied by a disconnection-connected fault in the T-zone. When a circuit breaker CT disconnects and a fault occurs in the T-zone of the disconnected string, the Lissajous curves of the sum of the incoming and outgoing currents and the fault component current flowing through the intermediate circuit breaker in step 3, and the sum of the fault component current flowing through the upper circuit breaker, are not on the coordinate axis and fall into quadrants 2 and 4. At this time, it is necessary to analyze the Lissajous curves of the fault component currents of the six intermediate circuit breakers and the sum of the fault component currents of the six intermediate circuit breakers. The string with the slope closest to 1 is selected as the suspicious string. At this time, the disconnected string is the suspicious string. Disconnect the circuit breaker of this string. The Lissajous curves of the sum of the fault component currents flowing through the other five intermediate circuit breakers and the sum of the fault component currents flowing through the other five incoming and outgoing lines do not meet the bus fault criterion, and can be correctly identified as a fault in the T-zone of this string.

[0071] c) Circuit breaker CT disconnection accompanied by non-disconnection fault in the T-zone When a circuit breaker CT disconnects and is accompanied by a non-disconnected series fault in zone T, the Lissajous curves of the sum of the incoming and outgoing currents in step 3 and the fault component of the current flowing through the intermediate circuit breaker and the sum of the fault component of the current flowing through the upper circuit breaker are not on the coordinate axis and fall into quadrants 1 and 3. This is identified as a fault in zone T, and then fault selection is performed.

[0072] Embodiment 1 of this application provides a substation protection method for a 3 / 2 connection switchgear station based on fault component Lissajous curves. The method for determining the fault location when a phase-A ground fault occurs on busbar 1 of the switchgear station and the current transformers (CTs) within the station are functioning normally includes the following steps: The fault component current information is collected, and the Lissajous curve positions of the sum of the fault components of the current flowing into the station from the upper and lower incoming and outgoing lines are analyzed to determine the fault within the station. Then, the Lissajous curve positions of the sum of the fault components of the current flowing into the switch station from the upper and lower incoming and outgoing lines and the sum of the fault components of the current from the intermediate circuit breaker are analyzed to determine the fault area. The Lissajous curve positions of the sum of the currents of the six upper incoming and outgoing lines and the fault components of the current flowing through the intermediate circuit breaker and the sum of the fault components of the current flowing through the upper circuit breaker are used for preliminary identification. The slope of this curve satisfies (-1.05~-0.95) above, so it is a fault on bus 1. Figure 3 , Figure 4 , Figure 5 The diagrams shown are the fault component waveform, Lissajous figure, and trip signal diagram under this operating condition.

[0073] Example 2: Embodiment 2 of this application provides a station area protection method for a 3 / 2 connection switchgear based on fault component Lissajous curves. When a phase-A ground fault occurs in zone T of the second string of the switchgear and the CTs within the station are functioning normally, the method for determining the fault location includes the following steps: The fault component current information is collected, and the position of the Lissajous curve of the sum of the fault components of the current flowing into the station from the upper and lower incoming and outgoing lines is analyzed to determine the fault within the station. Then, the position of the Lissajous curve of the sum of the fault components of the current flowing into the switch station from the upper and lower incoming and outgoing lines is analyzed to determine the fault area. The position of the Lissajous curve of the sum of the fault components of the current flowing through the intermediate circuit breaker and the sum of the fault components of the current flowing through the upper circuit breaker of the six strings of upper incoming and outgoing lines is used for preliminary identification. Since this curve is on the coordinate axis, it is a fault in zone T. Finally, the fault string is locked by comparing the slope of the Lissajous curve of the fault components of the current flowing through the six strings of intermediate circuit breakers with the sum of the fault components of the current flowing through the six strings of intermediate circuit breakers. Figure 6 , Figure 7 , Figure 8 The diagrams shown are the fault component waveform, Lissajous figure, and trip signal diagram under this operating condition.

[0074] Example 3: Embodiment 3 of this application provides a 3 / 2 connection switch station area protection method based on fault component Lissajous curves. The method for determining the fault location when a phase-A ground fault occurs on the busbar of the switch station and the first series of incoming and outgoing current transformers (CTs) is disconnected includes the following steps: The fault component current information is collected, and the Lissajous curve positions of the sum of the fault components of the current flowing into the station from the upper and lower incoming and outgoing lines are analyzed to determine the fault within the station. Then, the Lissajous curve positions of the sum of the fault components of the current flowing into the switch station from the upper and lower incoming and outgoing lines and the sum of the fault components of the current from the intermediate circuit breaker are analyzed to determine the fault area. The Lissajous curve positions of the sum of the currents of the six upper incoming and outgoing lines and the fault components of the current flowing through the intermediate circuit breaker and the sum of the fault components of the current flowing through the upper circuit breaker are used for preliminary judgment. The curves are in quadrants 2 and 4. At this time, it is necessary to identify whether there is a CT disconnection at a certain circuit breaker. Since there is no such disconnection, the final judgment is that it is a bus fault. Figure 9 , Figure 10 , Figure 11 The diagrams shown are the fault component waveform, Lissajous figure, and trip signal diagram under this operating condition.

[0075] Example 4: Embodiment 4 of this application provides a 3 / 2 connection switch station area protection method based on fault component Lissajous curves. The method for determining the fault location when an A-phase ground fault occurs in the upper T zone of the second string of the switch station and the CT at the intermediate circuit breaker of the second string is disconnected includes the following steps: The fault component current information is collected, and the position of the Lissajous curve of the sum of the fault components of the current flowing into the station from the upper and lower incoming and outgoing lines is analyzed to determine the fault within the station. Then, the position of the Lissajous curve of the sum of the fault components of the current flowing into the switch station from the upper and lower incoming and outgoing lines is analyzed to determine the fault area. Next, it is checked whether there is a CT break at the intermediate circuit breaker. If there is, the current of the intermediate circuit breaker in the broken string is replaced by the current of the lower incoming and outgoing lines and the current of the lower circuit breaker. The following judgment is made. The position of the Lissajous curve of the sum of the current of the six upper incoming and outgoing lines and the fault component of the current flowing through the intermediate circuit breaker is used to make a preliminary judgment. Since the curve is on the coordinate axis, it is a fault in zone T. Finally, the fault string is locked by comparing the slope of the Lissajous curve of the fault components of the current of the six intermediate circuit breakers with the sum of the fault components of the current of the six intermediate circuit breakers. Figure 12 , Figure 13 , Figure 14 The diagrams shown are the fault component waveform, Lissajous figure, and trip signal diagram under this operating condition.

[0076] Example 5: Embodiment 5 of this application provides a 3 / 2 connection switch station area protection method based on fault component Lissajous curves. The method for determining the fault location when an A-phase ground fault occurs on the main bus of the switch station and the CT at the fourth series circuit breaker is disconnected includes the following steps: The fault component current information is collected, and the position of the Lissajous curve of the sum of the fault components of the current flowing into the station from the upper and lower incoming and outgoing lines is analyzed to determine the fault within the station. Then, the position of the Lissajous curve of the sum of the fault components of the current flowing into the switch station from the upper and lower incoming and outgoing lines is analyzed to determine the fault area. Then, the position of the Lissajous curve of the sum of the fault components of the current flowing through the intermediate circuit breaker and the sum of the fault components of the current flowing through the upper side circuit breaker is analyzed to make a preliminary judgment. This curve is in quadrants 2 and 4, so it is necessary to compare the slope of the Lissajous curve of the fault components of the current flowing through the six intermediate circuit breakers with the sum of the fault components of the current flowing through the six intermediate circuit breakers to lock the suspected string as the fourth string. In the next time window, the CT of the fourth string side circuit breaker is identified as disconnected. At this time, the fourth string side circuit breaker needs to be disconnected. The Lissajous curve of the sum of the fault components of the current flowing into the switch station from the upper and outgoing lines and the sum of the fault components of the current flowing through the intermediate circuit breaker is located in quadrants 1 and 3, which is determined to be a bus fault. Figure 15 , Figure 16 , Figure 17The images show the fault component waveform, Lissajous figure, and trip signal diagram under this operating condition. Figure 18 , Figure 19 , Figure 20 The figures show the fault component waveform, Lissajous figure, and trip signal diagram after the circuit breaker is disconnected under this operating condition.

[0077] Example 6: Embodiment 6 of this application provides a 3 / 2 connection switch station area protection method based on fault component Lissajous curves. When an A-phase ground fault occurs in the T-zone of the second string of the switch station and the CT at the second string's side circuit breaker is disconnected, the fault location is determined by the following steps: The system collects fault component current information, analyzes the Lissajous curve positions of the sum of the fault components of the current flowing into the station from the upper and lower incoming and outgoing lines, and the sum of the fault components of the current flowing into the station from the lower incoming and outgoing lines to determine the fault within the station. Then, it analyzes the Lissajous curve positions of the sum of the fault components of the current flowing into the switchyard from the upper and lower incoming and outgoing lines, and the sum of the fault components of the current flowing through the intermediate circuit breaker to determine the fault area. Finally, it analyzes the Lissajous curve positions of the sum of the currents from the six upper incoming and outgoing lines and the fault components of the current flowing through the intermediate circuit breaker, and the sum of the fault components of the current flowing through the upper circuit breaker, to make a preliminary judgment. Since the curve is in quadrants 2 and 4, it is necessary to compare the slope of the Lissajous curve of the current fault components of the six intermediate circuit breakers with the sum of the current fault components of the six intermediate circuit breakers to identify the suspected string as the second string. In the next time window, the CT of the second string's side circuit breaker is identified as disconnected. At this time, the second string's side circuit breaker needs to be disconnected. Analyze the Lissajous curve of the sum of the current fault components flowing into the switch station from the other five strings' incoming and outgoing lines with the sum of the current fault components of the intermediate circuit breakers. If the curve is in quadrants 2 and 4, it is determined to be a fault in the T zone of the second string, and the bus protection is blocked. Figure 21 , Figure 22 , Figure 23 The images show the fault component waveform, Lissajous figure, and trip signal diagram under this operating condition. Figure 24 , Figure 25 , Figure 26 The figures show the fault component waveform, Lissajous figure, and trip signal diagram after the circuit breaker is disconnected under this operating condition.

[0078] It should be noted that the basic principles of the methods proposed in Embodiments 1-6 are basically the same. Each embodiment illustrates the discrimination of different fault conditions. The working principle of the method of this application is described in detail in Embodiment 1, while it is not elaborated in detail in Embodiments 2-6. Only the fault component waveform diagram, Lissajous curve diagram and trip signal diagram under the corresponding fault conditions are given. Based on the detailed description of Embodiment 1 and the illustrated results of Embodiments 2-6, those skilled in the art can clearly understand and implement the technical solution of this application. Therefore, the same working principle will not be described again.

[0079] In summary, the 3 / 2 connection switchyard protection method based on fault component Lissajous curves provided in this application utilizes the switchyard protection device to collect current data of all circuit breakers and incoming / outgoing lines in the station. Based on the instantaneous values ​​of the fault component currents, a Lissajous curve is constructed to effectively identify faults within the station. This method can identify faulty components in the busbars and T-zones of the switchyard when any CT disconnects and is accompanied by a fault within the station, unlike previous methods that only identified faults in a single bay. This method is scientifically sound, computationally simple, easy to implement, accurate, highly applicable, highly sensitive, and has a certain degree of fault tolerance.

[0080] Example 7 This application also provides a 3 / 2 wiring switch station area protection device based on fault component Lissajous curves, used to implement the methods described in any of the above embodiments, such as... Figure 27 As shown, the device includes: The station fault identification module 2701 is configured to acquire the current fault components of each circuit breaker and incoming and outgoing line in the switch station; and to determine whether a station fault has occurred based on the Lissajous curve characteristics of the upper incoming and outgoing line current fault components and the lower incoming and outgoing line current fault components flowing into the station. The fault area discrimination module 2702 is configured to, after the fault is determined to be within the station, determine whether the fault area is the upper or lower half of the switch station based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents and the fault components of the intermediate circuit breaker currents. The fault type discrimination module 2703 is configured to, after the fault area is determined, determine the fault type as bus fault or T-zone fault based on the Lissajous curve characteristics of the incoming and outgoing line current fault components, intermediate circuit breaker current fault components and side circuit breaker current fault components. The fault string location module 2704 is configured to locate the fault string based on the slope characteristics of the Lissajous curve of the fault component of the current of the intermediate circuit breaker in each string when the fault is identified as a T-zone fault.

[0081] This application also provides a computer-readable storage medium storing computer instructions. When the computer instructions are executed on a computer, the computer performs the technical solution of the wiring switch station domain protection method described in Embodiment 3 / 2.

[0082] This application also provides a computer program product, which includes a computer program stored in a computer-readable storage medium. At least one processor can read the computer program from the computer-readable storage medium. When the at least one processor executes the computer program, it can implement the technical solution of the 3 / 2 wiring switch station domain protection method in the above embodiments.

[0083] In the several embodiments provided in this application, it should be understood that the disclosed apparatus 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 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.

[0084] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to implement the solution of this embodiment according to actual needs.

[0085] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit. The unit composed of the above modules can be implemented in hardware or in the form of hardware plus software functional units.

[0086] The integrated modules described above, implemented as software functional modules, can be stored in a computer-readable storage medium. These software functional modules, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods of the various embodiments of this application.

[0087] It should be understood that the aforementioned processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly manifested as execution by a hardware processor, or execution by a combination of hardware and software modules within the processor.

[0088] The memory may include high-speed RAM, and may also include non-volatile storage (NVM), such as at least one disk storage device, and may also be a USB flash drive, external hard drive, read-only memory, disk or optical disc, etc.

[0089] Buses can be Industry Standard Architecture (ISA) buses, Peripheral Component Interconnect (PCI) buses, or Extended Industry Standard Architecture (EISA) buses, etc. Buses can be categorized into address buses, data buses, control buses, etc.

[0090] The aforementioned storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0091] An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Alternatively, the storage medium can be an integral part of the processor. The processor and storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and storage medium can exist as discrete components in an electronic control unit or main control device.

[0092] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for station area protection of a 3 / 2 wiring switchgear station based on fault component Lissajous curves, characterized in that, The method includes: Obtain the current fault components of each circuit breaker and incoming / outgoing line in the substation; based on the Lissajous curve characteristics of the upper and lower incoming / outgoing line current fault components flowing into the substation, determine whether a fault has occurred in the substation. After identifying the fault as an internal fault, based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents and the fault components of the intermediate circuit breaker currents, the fault area is determined to be either the upper or lower half of the switching station. After identifying the fault area, based on the Lissajous curve characteristics of the fault components of incoming and outgoing line current, intermediate circuit breaker current, and side circuit breaker current, the fault type is determined to be either a bus fault or a T-zone fault. When a fault is identified as a T-zone fault, the fault string is located based on the slope characteristics of the Lissajous curve of the fault component of the current in the intermediate circuit breaker of each string.

2. The method for station area protection of 3 / 2-connection switchgear based on fault component Lissajous curves according to claim 1, characterized in that, Based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents within the station, it is determined whether a fault has occurred within the station, including: When the positive direction of the fault component current of the upper and lower incoming and outgoing lines is flowing into the switch station, the Lissajous curves of the sum of the fault components of the upper and lower incoming and outgoing line currents are obtained with a time window of a set length. The judgment is made based on the Lissajous curves. When the first criterion and the second criterion are satisfied at the same time, it is determined to be an in-station fault. The first criterion is: (1) The second criterion is: (2) In the formula: , These are the fault component phase currents flowing into the switchyard from the upper and lower incoming / outgoing lines, respectively.

3. The method for station area protection of 3 / 2-connection switchgear based on fault component Lissajous curves according to claim 2, characterized in that, After identifying the fault as an in-station fault, based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents and the intermediate circuit breaker current, the fault area is determined to be either the upper or lower half of the switching station, including: When the positive direction of the fault component current flowing through the intermediate circuit breaker is from the lower busbar to the upper busbar, and the switchyard is divided into upper and lower parts with the intermediate circuit breaker being the overlapping area of ​​the two parts, after identifying the fault within the station, the fault is determined based on the Lissajous curve of the sum of the fault components of the upper incoming and outgoing line currents and the sum of the fault components of the intermediate circuit breaker current. When the third criterion is met, the fault area is determined to be the upper half of the switchyard; wherein, the third criterion is: (3) In the formula: The fault component phase current flowing through the intermediate circuit breaker; After identifying a fault within the station, a Lissajous curve is used to determine the fault area based on the sum of the fault components of the incoming and outgoing line currents and the sum of the fault components of the intermediate circuit breaker current. When the fourth criterion is met, the fault area is determined to be the lower half of the switching station. The fourth criterion is: (4)。 4. The method for station area protection of 3 / 2 wiring switchgear based on fault component Lissajous curves according to claim 1, characterized in that, After identifying the fault area, based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents, the fault type is determined to be either a bus fault or a T-zone fault, including: When the positive direction of the fault current component of the upper and lower circuit breakers flows out from the upper and lower busbars, after the fault area is determined, the Lissajous curve is used to determine the fault area. When the fifth criterion is met, it is determined to be a busbar fault; when the sixth criterion is met, it is determined to be a T-zone fault. The fifth criterion is: (5) The sixth criterion is: (6) In the formula: , These are the fault component phase currents flowing into the switchyard from the upper and lower incoming / outgoing lines, respectively. The fault component phase current flowing through the intermediate circuit breaker, , These are the differential current fault components of the upper busbar and the lower busbar, respectively.

5. The method for station area protection of 3 / 2-connection switchgear based on fault component Lissajous curves according to claim 4, characterized in that, When identifying a fault as zone T, the fault string is located based on the slope characteristics of the Lissajous curve of the fault current component of each intermediate circuit breaker, including: After determining that the fault is in zone T, the fault is determined based on the Lissajous curve of the fault current component of each string and the sum of the fault current components of each string's intermediate circuit breaker. The string with the slope closest to 1 is then identified as the fault string.

6. The method for station area protection of 3 / 2-connection switchgear based on fault component Lissajous curves according to claim 1, characterized in that, The method also includes handling of broken CT lines in and out, specifically including: When a current transformer (CT) disconnects in an incoming or outgoing line, the fault component of the incoming or outgoing line current is set to zero, and the fault identification within the station and the fault area are continued. If the incoming / outgoing line CT disconnection is accompanied by a bus fault, when determining the fault type, the Lissajous curve based on the sum of the fault components of the incoming / outgoing line current and the intermediate circuit breaker current and the sum of the fault components of the upper side circuit breaker current falls into the second or fourth quadrant, and there is no side circuit breaker disconnection, then it is still determined to be a bus fault. If the incoming / outgoing line CT disconnection is accompanied by a fault in zone T, when determining the fault type, if the Lissajous curve of the sum of the fault components of the upper incoming / outgoing line current and the intermediate circuit breaker current and the upper circuit breaker current is located on the coordinate axis, it is determined to be a fault in zone T, and fault string location is performed.

7. The method for station area protection of 3 / 2 wiring switchgear based on fault component Lissajous curves according to claim 1, characterized in that, The method also includes handling the disconnection of the intermediate circuit breaker CT, specifically including: When a CT disconnection is detected at an intermediate circuit breaker in a certain string, a substitute current is used to replace the fault component of the intermediate circuit breaker current in the disconnected string. The substitute current is calculated based on the incoming and outgoing currents of the column where the disconnected string is located and the current of the circuit breaker below it, so that subsequent fault identification is not affected.

8. The method for station area protection of 3 / 2 wiring switchgear based on fault component Lissajous curves according to claim 1, characterized in that, The method also includes handling the disconnection of the CT in the side circuit breaker, specifically including: When a circuit breaker CT disconnects, the current fault component at the circuit breaker in that series is set to zero, and the identification of faults and fault areas within the station continues. If a circuit breaker current transformer (CT) disconnection is accompanied by a busbar fault, when determining the fault type, based on the Lissajous curve of the sum of the incoming and outgoing currents and the fault components of the intermediate circuit breaker currents and the sum of the fault components of the upper side circuit breaker currents falling into the second or fourth quadrant, the string with the slope closest to 1 is selected as the suspected string based on the Lissajous curve of the fault components of the intermediate circuit breakers in each string and the sum of the fault components of the intermediate circuit breakers in each string. If the disconnected string is not a suspected string, it is directly determined to be a busbar fault. If the disconnected string is a suspected string, the side circuit breaker of that string is disconnected, and the fault is determined based on the fault components of the currents of the remaining branches. If the busbar fault criterion is met, it is determined to be a busbar fault. If the circuit breaker CT disconnection is accompanied by a fault in the T-zone of the disconnected string, when determining the fault type, the Lissajous curve of the sum of the fault components of the upper incoming and outgoing current and the intermediate circuit breaker current and the upper side circuit breaker current falls into the second or fourth quadrant. The disconnected string is the suspected string with the slope closest to 1. After disconnecting the circuit breaker of the string, the fault is determined based on the fault components of the current in the other branches. If the bus fault criterion is not met, it is determined to be a fault in the T-zone of the string. If the circuit breaker CT disconnection is accompanied by a non-disconnection series fault in zone T, when determining the fault type, if the Lissajous curve of the sum of the fault components of the upper incoming and outgoing current and the intermediate circuit breaker current and the upper circuit breaker current falls into the first quadrant or the third quadrant, it is determined to be a fault in zone T, and fault series location is performed.

9. A station area protection device for a 3 / 2 wiring switchgear based on fault component Lissajous curves, characterized in that, The device includes: The station fault detection module is configured to acquire the current fault components of each circuit breaker and incoming and outgoing line in the switch station; and determine whether a station fault has occurred based on the Lissajous curve characteristics of the upper and lower incoming and outgoing line current fault components flowing into the station. The fault area identification module is configured to, after identifying a fault as an in-station fault, determine whether the fault area is the upper or lower half of the switch station based on the Lissajous curve characteristics of the fault components of the incoming and outgoing line currents and the fault components of the intermediate circuit breaker currents. The fault type discrimination module is configured to, after identifying the fault area, determine the fault type as bus fault or T-zone fault based on the Lissajous curve characteristics of the incoming and outgoing line current fault components, intermediate circuit breaker current fault components and side circuit breaker current fault components. The fault string location module is configured to locate the fault string based on the slope characteristics of the Lissajous curve of the fault component of the current of the intermediate circuit breaker in each string when the fault is identified as a T-zone fault.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the 3 / 2 wiring switch station domain protection method based on fault component Lissajous curves as described in any one of claims 1-8.

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