CN-115296274-B - Fault positioning and bus protection method and system

CN115296274BCN 115296274 BCN115296274 BCN 115296274BCN-115296274-B

Abstract

The invention discloses a fault positioning and bus protection method and system. The fault positioning and bus protection method comprises the steps of collecting simulation information and switch information of a fault positioning and bus protection system, determining the area where a fault point is located according to the simulation information, and controlling the switch located in the area where the fault point is located to be disconnected according to the area where the fault point is located and the switch information. The embodiment of the invention judges the fault location and bus protection system fault area by collecting the analog information of the secondary side of the first main transformer and the secondary side of the second main transformer, and performs the disconnection operation on the switch of the fault location and bus protection system fault area by collecting the switch information of the secondary side of the first main transformer and the secondary side of the second main transformer, thereby realizing the accurate judgment and the accurate isolation of the fault location and bus protection system fault area.

Inventors

NI MIAOSHENG
CHEN XIAOBIN
XIE HUIFAN
SUN YUTONG
HUANG ZUWEI
CHEN RUJIA

Assignees

广东电网有限责任公司
广东电网有限责任公司揭阳供电局
中国南方电网有限责任公司

Dates

Publication Date: 20260505
Application Date: 20220810

Claims (9)

1. The fault positioning and bus protection method is characterized by being applied to a fault positioning and bus protection system, wherein the fault positioning and bus protection system at least comprises a main transformer and buses, the main transformer comprises a first main transformer and a second main transformer, the buses comprise a first bus and a second bus, the first bus is connected with the secondary side of the first main transformer, the second bus is connected with the secondary side of the second main transformer, a contact switch is arranged between the first bus and the second bus, a plurality of feeder lines and a grounding transformer are connected to each bus, the grounding transformer is grounded through a small resistor, and a switch is arranged between each bus and the main transformer, the grounding transformer and the feeder lines; the method comprises the following steps: Acquiring simulation information and switch information of a fault positioning and bus protection system; Determining the area where the fault point is located according to the simulation information; According to the area where the fault point is located and the switch information, controlling the switch located in the area where the fault point is located to be disconnected; and controlling the switch positioned in the area where the fault point is positioned to be disconnected according to the area where the fault point is positioned and the switch information, wherein the method comprises the following steps: When the zero sequence current transformer of the grounding transformer fails, a switch on the primary side of the grounding transformer is controlled to be disconnected, and the protection of the grounding transformer is locked; when the bus area fails, controlling a switch of the bus area to be disconnected after a step difference, and locking a standby automatic input device; when the high-resistance ground fault from the secondary side coil of the main transformer to the area between the switches of the secondary side of the main transformer, the switches of the secondary side of the main transformer are controlled to be disconnected after one step difference; When the feeder line has single-phase earth fault or at least two feeder lines are in an outer ring network of the station and have single-phase earth fault, the switch of the feeder line with fault is controlled to be disconnected after one level difference, and the reclosing of the feeder line is locked.
2. The fault location and bus protection method of claim 1, wherein the collecting analog information and switching information of the fault location and bus protection system comprises: The method comprises the steps of collecting simulation information of a fault positioning and bus protection system through a zero-sequence current transformer, wherein the wiring mode of the secondary side of the main transformer of the fault positioning and bus protection system is triangular wiring, and the simulation information comprises three-phase current and zero-sequence current of the secondary side of the main transformer, three-phase current and zero-sequence current of each feeder line, three-phase current and zero-sequence current of the primary side of a grounding transformer, zero-sequence current of a small resistor of the secondary side of the grounding transformer and capacitive current of each interval; And collecting the switch information of the fault positioning and bus protection system, wherein the switch information comprises the switch position of the secondary side of the main transformer, the position of the interconnection switch, the switch position of each feeder line and the switch position of the grounding transformer.
3. The fault location and bus protection method according to claim 2, wherein determining the area where the fault point is located according to the simulation information comprises: determining a zero sequence current transformer fault of the grounding transformer according to the three-phase current of the primary side of the grounding transformer and the zero sequence current of the secondary side of the grounding transformer; Determining a bus area fault according to the vector sum of the total zero sequence current of the fault positioning and bus protection system and a zero sequence vector sum threshold value, wherein the bus area fault comprises a bus short-circuit fault, a dead zone short-circuit fault close to a tie switch, a short-circuit fault close to a bus side of each feeder line and a short-circuit fault close to the bus side of a switch of a secondary side of the main transformer; determining that a high-resistance ground fault occurs in a region between a secondary side coil of a main transformer and a switch of the secondary side of the main transformer according to the zero sequence current of the secondary side of the main transformer and the magnitude and direction of the zero sequence current of the small resistor of the secondary side of the grounding transformer; And determining that the feeder line has single-phase grounding faults according to the magnitude and the direction of the zero-sequence current of the feeder line and the zero-sequence current of the small resistor on the secondary side of the grounding transformer, or determining that at least two feeder lines are in an outer ring network of the station and have single-phase grounding faults.
4. The fault locating and bus bar protecting method as set forth in claim 3, wherein the determining the fault of the zero sequence current transformer of the ground transformer based on the three-phase current of the primary side of the ground transformer and the zero sequence current of the secondary side of the ground transformer comprises: Calculating the sum of the three-phase currents of the primary side of the grounding transformer according to the three-phase currents of the primary side of the grounding transformer; And comparing the sum of three-phase currents of the primary side of the grounding transformer with zero-sequence currents of the secondary side of the grounding transformer, and judging fault states of the current transformer of the primary side of the grounding transformer, the zero-sequence current transformer of the secondary side of the grounding transformer and the inside of the grounding transformer according to comparison results.
5. The fault location and bus bar protection method according to claim 4, wherein comparing the sum of three-phase currents of the primary side of the ground transformer with zero-sequence currents of the secondary side of the ground transformer, and determining the fault states of the primary side of the ground transformer, the zero-sequence current transformer of the secondary side of the ground transformer, and the inside of the ground transformer based on the comparison results, comprises: When I jd -I j0 I > I z1 , determining the zero sequence current transformer on the secondary side of the grounding transformer and the internal fault of the grounding transformer, wherein I z1 is a setting value, I jd is the sum of three-phase currents on the primary side of the grounding transformer, and I j0 is the zero sequence current on the secondary side of the grounding transformer.
6. A fault locating and busbar protection method according to claim 3, wherein determining a busbar zone fault from the vector sum and zero sequence vector sum threshold of the total zero sequence current of the fault locating and busbar protection system comprises: comparing the vector sum of the total zero sequence current of the fault positioning and bus protection system with a zero sequence vector sum threshold value to generate a comparison result; And determining the fault of the bus area according to the comparison result.
7. The fault locating and bus bar protecting method as set forth in claim 3, wherein the determining the high-resistance ground fault of the area between the secondary side of the main transformer to the switch of the secondary side of the main transformer according to the magnitude and direction of the zero-sequence current of the secondary side of the main transformer and the zero-sequence current of the small resistance of the secondary side of the ground transformer includes: comparing the zero sequence current of the secondary side of the main transformer with the zero sequence current of the small resistor of the secondary side of the grounding transformer; When the direction of the zero sequence current of the secondary side of the main transformer and the direction of the zero sequence current of the small resistor of the secondary side of the grounding transformer are opposite, the vector sum of the direction of the zero sequence current of the secondary side of the main transformer and the direction of the zero sequence current of the small resistor of the secondary side of the grounding transformer is zero, and the high-resistance grounding fault of the area between the secondary side coil of the main transformer and the switch of the secondary side of the main transformer is judged.
8. The fault locating and bus protecting method as set forth in claim 3, wherein the determining that the feeder line has a single-phase earth fault or determining that at least two feeder lines are out of a loop network and have a single-phase earth fault according to the magnitude and direction of the zero-sequence current of the feeder line and the zero-sequence current of the small resistance of the secondary side of the grounding transformer comprises: comparing the zero sequence current of the feeder line with the zero sequence current of the small resistor of the secondary side of the grounding transformer; When the zero sequence current of the feeder line is opposite to the zero sequence current of the small resistor on the secondary side of the grounding transformer, the vector sum of the zero sequence current of the feeder line and the zero sequence current of the small resistor on the secondary side of the grounding transformer is zero, and the maximum value of the zero sequence current of the feeder line is larger than X%. I j0 , the single-phase grounding fault of the feeder line is judged to occur, or at least two feeder lines are out of the site and are in ring network, and single-phase grounding fault occurs, wherein X% is a percentage, X% = 80% is set when a fault positioning and bus protection system does not have an out-of-site ring network, X% = 40% is set when two feeder lines on the same bus are out-of-site ring network, and X% = 30% is set when three feeder lines on the same bus are out-of-site ring network.
9. A fault location and bus protection system for performing the fault location and bus protection method as claimed in any one of claims 1-8, comprising: a main transformer and a bus bar are arranged, The main transformer comprises a first main transformer and a second main transformer, wherein the buses comprise a first bus and a second bus, the first bus is connected with the secondary side of the first main transformer, the second bus is connected with the secondary side of the second main transformer, a connecting switch is arranged between the first bus and the second bus, a plurality of feeder lines and a grounding transformer are connected to each bus, the grounding transformer is grounded through a small resistor, and a switch is arranged between each bus and the main transformer, the grounding transformer and the feeder lines; The zero sequence current transformer is used for collecting simulation information and switching information of the fault positioning and bus protection system; the fault positioning module is used for determining the area where the fault point is located according to the simulation information; and the control module is used for controlling the switch positioned in the area where the fault point is positioned to be disconnected according to the area where the fault point is positioned and the switch information.

Description

Fault positioning and bus protection method and system Technical Field The invention relates to the technical field of electric power, in particular to a fault positioning and bus protection method and system. Background The low-voltage side of the main transformer of the transformer substation is generally connected by adopting an angle connection method, so that the side is called a triangle side. Since the angle connection has no neutral point, grounding is typically achieved by artificially forming a ground point through a ground change. The most common grounding method in artificially formed grounding points is that the bus bar is grounded via a ground resistor. Because the triangle side bus is not provided with bus protection, when a fault occurs in the system after the bus is grounded through the grounding reducing resistor, the fault area cannot be accurately positioned and isolated. Disclosure of Invention The invention provides a fault positioning and bus protecting method and system, which can accurately position and isolate a fault area. According to one aspect of the invention, a fault positioning and bus protection method is provided, the method is applied to a fault positioning and bus protection system, the fault positioning and bus protection system at least comprises a main transformer and buses, the main transformer comprises a first main transformer and a second main transformer, the buses comprise a first bus and a second bus, the first bus is connected with the secondary side of the first main transformer, the second bus is connected with the secondary side of the second main transformer, a connecting switch is arranged between the first bus and the second bus, a plurality of feeder lines and a grounding transformer are connected to each bus, the grounding transformer is grounded through a small resistor, and a switch is arranged between each bus and the main transformer, the grounding transformer and the feeder lines; the method comprises the following steps: Acquiring simulation information and switch information of a fault positioning and bus protection system; Determining the area where the fault point is located according to the simulation information; And controlling the switch in the area where the fault point is located to be disconnected according to the area where the fault point is located and the switch information. Optionally, the collecting the analog information and the switch information of the fault positioning and bus protection system includes: The method comprises the steps of collecting simulation information of a fault positioning and bus protection system through a zero-sequence current transformer, wherein the wiring mode of the secondary side of the main transformer of the fault positioning and bus protection system is triangular wiring, and the simulation information comprises three-phase current and zero-sequence current of the secondary side of the main transformer, three-phase current and zero-sequence current of each feeder line, three-phase current and zero-sequence current of the primary side of a grounding transformer, zero-sequence current of a small resistor of the secondary side of the grounding transformer and capacitive current of each interval; And collecting the switch information of the fault positioning and bus protection system, wherein the switch information comprises the switch position of the secondary side of the main transformer, the position of the interconnection switch, the switch position of each feeder line and the switch position of the grounding transformer. Optionally, the determining, according to the simulation information, the area where the fault point is located includes: determining a zero sequence current transformer fault of the grounding transformer according to the three-phase current of the primary side of the grounding transformer and the zero sequence current of the secondary side of the grounding transformer; Determining a bus area fault according to the vector sum of the total zero sequence current of the fault positioning and bus protection system and a zero sequence vector sum threshold value, wherein the bus area fault comprises a bus short-circuit fault, a dead zone short-circuit fault close to a tie switch, a short-circuit fault close to a bus side of each feeder line and a short-circuit fault close to the bus side of a switch of a secondary side of the main transformer; determining that a high-resistance ground fault occurs in a region between a secondary side coil of a main transformer and a switch of the secondary side of the main transformer according to the zero sequence current of the secondary side of the main transformer and the magnitude and direction of the zero sequence current of the small resistor of the secondary side of the grounding transformer; And determining that the feeder line has single-phase grounding faults according to the magnitude and the direction of the zero-sequence current of the