CN116840623A - Ground fault test circuit - Google Patents
Ground fault test circuit Download PDFInfo
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- CN116840623A CN116840623A CN202310836785.5A CN202310836785A CN116840623A CN 116840623 A CN116840623 A CN 116840623A CN 202310836785 A CN202310836785 A CN 202310836785A CN 116840623 A CN116840623 A CN 116840623A
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- 238000012360 testing method Methods 0.000 title claims abstract description 42
- 238000010168 coupling process Methods 0.000 claims description 148
- 238000005859 coupling reaction Methods 0.000 claims description 148
- 230000008878 coupling Effects 0.000 claims description 120
- 239000003990 capacitor Substances 0.000 claims description 13
- 238000000034 method Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000001914 filtration Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
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- 238000001514 detection method Methods 0.000 description 1
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- 238000005259 measurement Methods 0.000 description 1
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- 238000006467 substitution reaction Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- Theoretical Computer Science (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The embodiment of the invention discloses a ground fault test circuit. The ground fault test circuit includes: the analog grounding resistance module is electrically connected with the bus to be tested; the sensor is used for detecting the current of each branch of the bus to be tested; the current-limiting resistor module is electrically connected with the bus to be tested and the analog grounding resistor module; the switch control module is electrically connected with the current limiting resistor module and used for controlling the on-off of each circuit of the switch control module and outputting voltage signals according to input signals, and the switch control module comprises a plurality of photoelectric couplers; and the controller is electrically connected with the switch control module and the sensor and is used for determining the resistance value of each resistor in the analog grounding resistance module according to the voltage signal and the current detected by the sensor so as to determine the branch where the grounding fault of the bus to be tested is located. The ground fault test circuit provided by the embodiment of the invention can improve the test efficiency.
Description
Technical Field
The embodiment of the invention relates to a ground fault detection technology, in particular to a ground fault test circuit.
Background
The transformer substation direct current system is a system for providing continuous and stable direct current power supply transmission for direct current equipment such as relay protection devices, measurement and control devices and the like in a transformer substation, and the probability of direct current ground fault is increased due to the civil structure of the transformer substation, wherein the power supply range of the direct current system relates to the condition that the insulation strength of a secondary cable in the transformer substation in rainy weather is reduced from an indoor relay protection cabinet to an outdoor high-voltage field. The reliability of the direct current system of the transformer substation plays a vital role in the safe operation of the transformer substation and the power plant. Therefore, in order to ensure the reliability of the direct current system of the transformer substation, the bus in the direct current system of the transformer substation needs to be subjected to a ground fault test.
At present, the existing ground fault test circuit, such as the ground fault test for the direct current bus of the transformer substation, is usually combined with a direct current leakage current method through a balanced bridge method, and the method has the defects that the fault is difficult to quickly locate due to the concealment of a ground point and the limitation of the method, so that the test efficiency is affected.
Disclosure of Invention
The embodiment of the invention provides a ground fault test circuit for improving test efficiency.
The embodiment of the invention provides a ground fault test circuit, which comprises:
the analog grounding resistance module is electrically connected with the bus to be tested;
the sensor is used for detecting the current of each branch of the bus to be tested;
the current-limiting resistor module is electrically connected with the bus to be tested and the analog grounding resistor module;
the switch control module is electrically connected with the current limiting resistor module and used for controlling the on-off of each circuit of the switch control module and outputting voltage signals according to input signals, and the switch control module comprises a plurality of photoelectric couplers;
and the controller is electrically connected with the switch control module and the sensor and is used for determining the resistance value of each resistor in the analog grounding resistance module according to the voltage signal and the current detected by the sensor so as to determine the branch where the grounding fault of the bus to be tested is located.
Optionally, the switch control module includes a first photoelectric coupling unit, a second photoelectric coupling unit, a third photoelectric coupling unit and a fourth photoelectric coupling unit; the input end of the first photoelectric coupling unit is electrically connected with the first end of the current-limiting resistor module, the first output end of the first photoelectric coupling unit is electrically connected with the controller, and the second output end of the first photoelectric coupling unit is electrically connected with the input end of the second photoelectric coupling unit; the control end of the second photoelectric coupling unit is electrically connected with the controller, the output end of the second photoelectric coupling unit is electrically connected with the input end of the third photoelectric coupling unit, and the output end of the second photoelectric coupling unit is grounded; the first output end of the third photoelectric coupling unit is electrically connected with the input end of the fourth photoelectric coupling unit, and the second output end of the third photoelectric coupling unit is electrically connected with the controller; the output end of the fourth photoelectric coupling unit is electrically connected with the second end of the current-limiting resistor module, and the control end of the fourth photoelectric coupling unit is electrically connected with the controller.
Optionally, each photoelectric coupling unit is provided with a respective photoelectric coupler and triode; the input end and the output end of a photoelectric coupler in the first photoelectric coupling unit are respectively used as the input end and the second output end of the first photoelectric coupling unit, and the first pole of a triode in the first photoelectric coupling unit is used as the first output end of the first photoelectric coupling unit; the input end of the photoelectric coupler in the second photoelectric coupling unit is used as the control end of the second photoelectric coupling unit, the output end of the photoelectric coupler in the second photoelectric coupling unit is grounded, and the first pole and the second pole of the triode in the second photoelectric coupling unit are respectively used as the input end and the output end of the second photoelectric coupling unit; the input end and the output end of the photoelectric coupler in the third photoelectric coupling unit are respectively used as the input end and the first output end of the third photoelectric coupling unit, and the first pole of the triode in the third photoelectric coupling unit is used as the second output end of the third photoelectric coupling unit; the input end of the photoelectric coupler in the fourth photoelectric coupling unit is used as the control end of the fourth photoelectric coupling unit, the output end of the photoelectric coupler in the fourth photoelectric coupling unit is grounded, and the first pole and the second pole of the triode in the fourth photoelectric coupling unit are respectively used as the input end and the output end of the fourth photoelectric coupling unit.
Optionally, each photoelectric coupling unit is further provided with a power supply, the second pole of the triode in the first photoelectric coupling unit is electrically connected with the power supply in the first photoelectric coupling unit, the input end of the photoelectric coupler in the second photoelectric coupling unit is electrically connected with the power supply in the second photoelectric coupling unit, the second pole of the triode in the third photoelectric coupling unit is electrically connected with the power supply in the third photoelectric coupling unit, and the input end of the photoelectric coupler in the fourth photoelectric coupling unit is electrically connected with the power supply in the fourth photoelectric coupling unit.
Optionally, the first photoelectric coupling unit and the third photoelectric coupling unit are both provided with a resistor and a capacitor, the first pole of the triode in the first photoelectric coupling unit is electrically connected with the resistor and the capacitor in the first photoelectric coupling unit, and the first pole of the triode in the third photoelectric coupling unit is electrically connected with the resistor and the capacitor in the third photoelectric coupling unit.
Optionally, the resistor comprises an adjustable resistor.
Optionally, the analog ground resistance module includes a first resistor and a second resistor; the first end of the first resistor is electrically connected with the positive electrode of the bus to be tested and is used as the first end of the analog grounding resistor module, the second end of the first resistor is grounded, the first end of the second resistor is electrically connected with the negative electrode of the bus to be tested and is used as the second end of the analog grounding resistor module, and the second end of the second resistor is electrically connected with the second end of the first resistor.
Optionally, the current limiting resistor module includes a third resistor and a fourth resistor, the first end of the first resistor is electrically connected with one end of the third resistor, the other end of the third resistor is used as the first end of the current limiting resistor module, the first end of the second resistor is electrically connected with one end of the fourth resistor, the other end of the fourth resistor is used as the second end of the current limiting resistor module, and the first end and the second end of the current limiting resistor module are respectively electrically connected with the input end and one output end of the switch control module.
Optionally, the analog grounding resistance module comprises a first end and a second end, the current limiting resistance module comprises a first end, a second end, a third end and a fourth end, the switch control module comprises an input end, a control end and three output ends, the input end and one of the output ends of the switch control module are respectively electrically connected with the first end and the second end of the current limiting resistance module, the control end of the switch control module is electrically connected with the output end of the controller, the other two output ends of the switch control module are respectively electrically connected with the input end of the controller, and the first end and the second end of the analog grounding resistance module are respectively electrically connected with the third end and the fourth end of the current limiting resistance module.
Optionally, the bus to be tested is a direct current bus of the transformer substation.
The ground fault test circuit provided by the embodiment of the invention comprises: the analog grounding resistance module is electrically connected with the bus to be tested; the sensor is used for detecting the current of each branch of the bus to be tested; the current-limiting resistor module is electrically connected with the bus to be tested and the analog grounding resistor module; the switch control module is electrically connected with the current limiting resistor module and used for controlling the on-off of each circuit of the switch control module and outputting voltage signals according to input signals, and the switch control module comprises a plurality of photoelectric couplers; and the controller is electrically connected with the switch control module and the sensor and is used for determining the resistance value of each resistor in the analog grounding resistance module according to the voltage signal and the current detected by the sensor so as to determine the branch where the grounding fault of the bus to be tested is located. According to the ground fault test circuit provided by the embodiment of the invention, the resistance value of each resistor in the analog ground resistor module is determined by the controller according to the voltage signal and the current detected by the sensor, the branch where the ground fault of the bus to be tested is located can be rapidly determined according to the resistance value of the resistor and the current detected by the sensor, the fault locating time is not influenced by the grounding point concealment, the problem that the fault is difficult to rapidly locate due to the grounding point concealment and the method limitation in the prior art is solved, and the test efficiency is improved.
Drawings
FIG. 1 is a block diagram of a ground fault test circuit according to a first embodiment of the present invention;
FIG. 2 is a block diagram of another ground fault test circuit according to a first embodiment of the present invention;
fig. 3 is a schematic structural diagram of a ground fault testing circuit according to a second embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.
Example 1
Fig. 1 is a block diagram of a ground fault test circuit according to an embodiment of the present invention. Referring to fig. 1, the ground fault test circuit includes: an analog ground resistance module 10, a sensor 20, a current limiting resistance module 30, a switch control module 40, and a controller 50.
The analog grounding resistance module 10 is electrically connected with a bus to be tested; the sensor 20 is used for detecting the current of each branch of the bus to be tested; the current limiting resistance module 30 is electrically connected with the bus to be tested and the analog grounding resistance module 10; the switch control module 40 is electrically connected with the current limiting resistor module 30, and is used for controlling the on-off of each circuit of the switch control module according to an input signal and outputting a voltage signal, and the switch control module 40 comprises a plurality of photoelectric couplers; the controller 50 is electrically connected to the switch control module 40 and the sensor 20, and is configured to determine, according to the voltage signal and the current detected by the sensor, the resistance value of each resistor in the analog ground resistance module 10, so as to determine the branch where the ground fault of the bus to be tested is located.
Specifically, the analog grounding resistance module 10 is configured to simulate the grounding resistance of the bus to be tested, and the current limiting resistance module 30 can limit the current transmitted from the bus to the switch control module 40, so as to prevent the circuit from being damaged due to excessive current. When the ground fault test circuit works, the controller 50 transmits a level signal, such as a high level signal or a low level signal, to the switch control module 40, for example, transmits a high level signal to the switch control module 40, the switch control module 40 controls the bus to be conducted with one loop formed by two photoelectric couplers in the switch control module 40 and outputs a first voltage signal, and transmits a low level signal to the switch control module 40, and the switch control module 40 controls the bus to be conducted with the other loop formed by the other two photoelectric couplers in the switch control module 40 and outputs a second voltage signal. The controller 50 can determine the resistance values of two resistors in the analog ground resistance module 10 according to the first voltage signal and the second voltage signal (taking the analog ground resistance module 10 including two resistors as an example, the two resistors are respectively connected with the bus positive pole km+ and the bus negative pole KM-, and determine the branch where the ground fault of the bus to be tested is located according to the current detected by the sensor 20). For example, if at least one of the resistances of the two resistors in the analog ground resistance module 10 is a certain value, but not infinitely large (the bus bar has no ground fault when the resistance is infinite), it indicates that the bus bar has a ground fault, and if the sensor 20 detects that the current in at least one branch is not zero (the branch connected to the bus bar has no ground fault when the current is zero), it indicates that the branch with the current not zero has a ground fault, so as to determine the branch where the ground fault of the bus bar exists.
In addition, if the resistance values of the two resistors in the analog ground resistance module 10 are infinity, it indicates that the bus has no ground fault, and if the sensor 20 detects that the current in at least one branch is not zero, it needs to further detect to determine whether the bus has a ground fault.
The ground fault test circuit provided in this embodiment includes: the analog grounding resistance module is electrically connected with the bus to be tested; the sensor is used for detecting the current of each branch of the bus to be tested; the current-limiting resistor module is electrically connected with the bus to be tested and the analog grounding resistor module; the switch control module is electrically connected with the current limiting resistor module and used for controlling the on-off of each circuit of the switch control module and outputting voltage signals according to input signals, and the switch control module comprises a plurality of photoelectric couplers; and the controller is electrically connected with the switch control module and the sensor and is used for determining the resistance value of each resistor in the analog grounding resistance module according to the voltage signal and the current detected by the sensor so as to determine the branch where the grounding fault of the bus to be tested is located. According to the ground fault test circuit provided by the embodiment, the resistance of each resistor in the analog ground resistor module is determined through the controller according to the voltage signal and the current detected by the sensor, the branch where the ground fault of the bus to be tested is located can be rapidly determined according to the resistance of the resistor and the current detected by the sensor, the fault locating time is not influenced by the grounding point concealment, the problem that the fault is difficult to rapidly locate due to the grounding point concealment and the method limitation in the prior art is solved, and therefore the test efficiency is improved.
Optionally, the switch control module 40 includes a first photoelectric coupling unit 41, a second photoelectric coupling unit 42, a third photoelectric coupling unit 43, and a fourth photoelectric coupling unit 44; the input end of the first photoelectric coupling unit 41 is electrically connected with the first end of the current-limiting resistor module, the first output end of the first photoelectric coupling unit 41 is electrically connected with the controller, and the second output end of the first photoelectric coupling unit 41 is electrically connected with the input end of the second photoelectric coupling unit; the control end of the second photoelectric coupling unit 42 is electrically connected with the controller, the output end of the second photoelectric coupling unit 42 is electrically connected with the input end of the third photoelectric coupling unit, and the output end of the second photoelectric coupling unit 42 is grounded; the first output end of the third photoelectric coupling unit 43 is electrically connected with the input end of the fourth photoelectric coupling unit 44, and the second output end of the third photoelectric coupling unit 43 is electrically connected with the controller; the output end of the fourth photoelectric coupling unit 44 is electrically connected to the second end of the current limiting resistor module, and the control end of the fourth photoelectric coupling unit 44 is electrically connected to the controller.
Fig. 2 is a block diagram illustrating another ground fault test circuit according to a first embodiment of the present invention. Referring to fig. 2, the switch control module 40 includes four photo-coupling units, when the controller 50 transmits a high-level signal to the switch control module 40, the switch control module 40 may control one loop formed by the bus and the first photo-coupling unit 41 and the second photo-coupling unit 42 to be conducted so as to output a first voltage signal, and when the controller 50 transmits a low-level signal to the switch control module 40, the switch control module 40 may control the other loop formed by the bus and the third photo-coupling unit 43 and the fourth photo-coupling unit 44 to be conducted so as to output a second voltage signal.
Optionally, the analog grounding resistor module 10 includes a first end and a second end, the current-limiting resistor module 30 includes a first end, a second end, a third end and a fourth end, the switch control module 40 includes an input end, a control end and three output ends, the input end and one of the output ends of the switch control module 40 are respectively electrically connected with the first end and the second end of the current-limiting resistor module 30, the control end of the switch control module 40 is electrically connected with the output end of the controller 50, the other two output ends of the switch control module 40 are respectively electrically connected with the input end of the controller 50, and the first end and the second end of the analog grounding resistor module 10 are respectively electrically connected with the third end and the fourth end of the current-limiting resistor module 30.
Specifically, referring to fig. 1 and 2, a first end of the current limiting resistor module 30 is electrically connected to an input end of the first photo coupling unit 41, and a second end of the current limiting resistor module 30 is electrically connected to an output end of the fourth photo coupling unit 44. The first end of the analog grounding resistance module 10 is electrically connected with the third end of the current limiting resistance module 30, the third end of the current limiting resistance module 30 is electrically connected with the bus anode KM+, the second end of the analog grounding resistance module 10 is electrically connected with the fourth end of the current limiting resistance module 30, and the fourth end of the current limiting resistance module 30 is electrically connected with the bus cathode KM-, so that a loop is formed among the bus, the current limiting resistance module 30, the switch control module 40 and the analog grounding resistance module 10.
Example two
Fig. 3 is a schematic structural diagram of a ground fault testing circuit according to a second embodiment of the present invention. Referring to fig. 3, this embodiment is based on the above embodiment, and optionally, each photo-coupling unit is provided with a respective photo-coupler and triode; the input end and the output end of the photoelectric coupler O1 in the first photoelectric coupling unit 41 are respectively used as the input end and the second output end of the first photoelectric coupling unit 41, and the first pole of the triode Q1 in the first photoelectric coupling unit 41 is used as the first output end of the first photoelectric coupling unit 41; the input end of the photoelectric coupler O2 in the second photoelectric coupling unit 42 is used as the control end of the second photoelectric coupling unit 42, the output end of the photoelectric coupler O2 in the second photoelectric coupling unit 42 is grounded, and the first pole and the second pole of the triode Q2 in the second photoelectric coupling unit 42 are respectively used as the input end and the output end of the second photoelectric coupling unit 42; the input end and the output end of the photoelectric coupler O3 in the third photoelectric coupling unit 43 are respectively used as the input end and the first output end of the third photoelectric coupling unit 43, and the first pole of the triode Q3 in the third photoelectric coupling unit 43 is used as the second output end of the third photoelectric coupling unit 43; the input end of the photo-coupler O4 in the fourth photo-coupling unit 44 is used as the control end of the fourth photo-coupling unit 44, the output end of the photo-coupler O4 in the fourth photo-coupling unit 44 is grounded, and the first pole and the second pole of the triode Q4 in the fourth photo-coupling unit 44 are used as the input end and the output end of the fourth photo-coupling unit 44, respectively.
Specifically, referring to fig. 3, when the level signal CB transmitted by the controller 50 (not shown in fig. 3) to the switch control module 40 is a high level signal, the photo coupler O2 in the second photo-coupling unit 42 is turned on, the turn-on loop in the circuit is a bus positive pole km+ -R3-O1-O2-C point (GND) -a point (GND) -R2-km+, the emitter of the output triode of the photo-coupler O1 in the first photo-coupling unit 41, that is, the first pole of the triode Q1 outputs a first voltage U1, the first voltage is output to the controller 50 after being filtered by a resistor and a capacitor, and the controller 50 can calculate the resistance value of the resistor R2 in the analog grounding resistor module 10 according to the first voltage. When the level signal CB transmitted by the controller 50 to the switch control module 40 is a low level signal, the conducting loop in the circuit is km+ -R1-a point (GND) -C point (GND) -O3-O4-R8-bus negative electrode KM-, the emitter of the output triode of the photocoupler O3 in the third photocoupler 43, that is, the first pole of the triode Q3 outputs the second voltage U2, the second voltage is filtered by the resistor and the capacitor and then is output to the controller 50, and the controller 50 can calculate the resistance value of the resistor R1 in the analog grounding resistor module 10 according to the second voltage.
In addition, the clamp meter in fig. 3 is a sensor, and one feeder branch connected with the bus positive electrode is grounded through a resistor Rd (Rd and R1 are the same resistor). When the input end of the fourth photoelectric coupling unit 44 is at a low level, the photoelectric coupler O4 in the fourth photoelectric coupling unit 44 is turned on, the bus anode KM-is grounded through the resistor R4, so that the current in the loop Rd-B point-C point-O3-O4-R8-bus anode KM-forms a loop, the current detected by the sensor is a current Id (the current returned to the bus anode KM-is I1) caused by the dc ground resistor Rd, and the controller can determine the branch where the ground fault is based on the current detected by the sensor.
With continued reference to fig. 3, optionally, each optocoupler unit is further provided with a power source, the second pole of the transistor Q1 in the first optocoupler unit 41 is electrically connected to the power source V1 in the first optocoupler unit 41, the input end of the optocoupler O2 in the second optocoupler unit 42 is electrically connected to the power source V2 in the second optocoupler unit 42, the second pole of the transistor Q3 in the third optocoupler unit 43 is electrically connected to the power source V3 in the third optocoupler unit 43, and the input end of the optocoupler O4 in the fourth optocoupler unit 44 is electrically connected to the power source V4 in the fourth optocoupler unit 44. Illustratively, each power supply is a 5V power supply, one end of each power supply is connected to a triode or a photocoupler, and the other end of each power supply is grounded.
Optionally, the first photo-coupling unit 41 and the third photo-coupling unit 42 are each provided with a resistor and a capacitor, the first pole of the transistor Q1 in the first photo-coupling unit 41 is electrically connected to the resistor and the capacitor in the first photo-coupling unit 41, and the first pole of the transistor Q3 in the third photo-coupling unit 43 is electrically connected to the resistor and the capacitor in the third photo-coupling unit 43.
The resistor and the capacitor may play a role of filtering, for example, the voltage generated by the first pole of the triode Q1 in the first optocoupler unit 41 is output after being filtered by the resistor and the capacitor.
Optionally, the resistor comprises an adjustable resistor.
Specifically, the resistance of the adjustable resistor is adjustable, for example, by adjusting the resistance of the adjustable resistor connected to the triode Q1 in the first photoelectric coupling unit 41, different filtering effects of the voltage generated by the first pole of the triode Q1 in the first photoelectric coupling unit 41 can be achieved.
Optionally, the analog ground resistance module 10 includes a first resistor R1 and a second resistor R2; the first end of the first resistor R1 is electrically connected with the positive pole KM+ of the bus to be tested and serves as the first end of the analog grounding resistor module 10, the second end of the first resistor R1 is grounded, the first end of the second resistor R2 is electrically connected with the negative pole KM-of the bus to be tested and serves as the second end of the analog grounding resistor module 10, and the second end of the second resistor R2 is electrically connected with the second end of the first resistor R1.
The first resistor R1 is a grounding resistor of the positive pole KM+ of the bus to be tested, and the second resistor R2 is a grounding resistor of the negative pole KM-of the bus to be tested. When the first resistor R1 and the second resistor R2 are reduced at the same time, the controller 50 may determine, according to the first voltage and the second voltage output by the switch control module 40, two equations and solve the two equations in parallel to obtain the resistance value of the first resistor R1 and the resistance value of the second resistor R2, so as to determine the branch where the ground fault of the bus is located according to the resistance value of the first resistor R1 and the resistance value of the second resistor R2.
Optionally, the current limiting resistor module 30 includes a third resistor R3 and a fourth resistor R4, the first end of the first resistor R1 is electrically connected to one end of the third resistor R3, the other end of the third resistor R3 is used as the first end of the current limiting resistor module 30, the first end of the second resistor R2 is electrically connected to one end of the fourth resistor R4, the other end of the fourth resistor R4 is used as the second end of the current limiting resistor module 30, and the first end and the second end of the current limiting resistor module 30 are respectively electrically connected to the input end and one output end of the switch control module 40.
Specifically, referring to fig. 3, two ends of the third resistor R3 are electrically connected to the bus positive electrode km+ (the first end of the first resistor R1) and the input end of the photo coupler O1 in the first photo coupling unit 41, and two ends of the fourth resistor R4 are electrically connected to the bus negative electrode KM- (the first end of the second resistor R2) and the second pole of the transistor Q4 in the fourth photo coupling unit 44, respectively. The third resistor R3 may limit the current transmitted from the bus positive electrode km+ to the photocoupler O1 in the first photocoupling unit 41 through the third resistor R3, and the fourth resistor R4 may limit the current transmitted from the photocoupler O4 in the fourth photocoupling unit 44 to the bus negative electrode KM-.
Optionally, the bus to be tested is a direct current bus of the transformer substation.
Specifically, the ground fault test circuit can perform a direct current ground fault test for a direct current bus in the direct current system of the transformer substation, and determine a branch where the direct current ground fault of the direct current bus is located, so as to improve the reliability of the direct current system of the transformer substation.
According to the ground fault test circuit provided by the embodiment, the resistance value of the first resistor and the resistance value of the second resistor are determined through the controller according to the first voltage and the second voltage, the branch where the ground fault of the bus to be tested is located can be rapidly determined according to the resistance values of the first resistor and the second resistor and the current detected by the sensor, the fault locating time is not influenced by the concealment of the ground point, the problem that the fault is difficult to rapidly locate due to the concealment of the ground point and the limitation of the method in the prior art is solved, and therefore the test efficiency is improved.
Note that the above is only a preferred embodiment of the present invention and the technical principle applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, and that various obvious changes, rearrangements, combinations, and substitutions can be made by those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims.
Claims (10)
1. A ground fault test circuit, comprising:
the analog grounding resistance module is electrically connected with the bus to be tested;
the sensor is used for detecting the current of each branch of the bus to be tested;
the current limiting resistor module is electrically connected with the bus to be tested and the analog grounding resistor module;
the switch control module is electrically connected with the current limiting resistor module and used for controlling the on-off of each circuit of the switch control module and outputting voltage signals according to input signals, and the switch control module comprises a plurality of photoelectric couplers;
and the controller is electrically connected with the switch control module and the sensor and is used for determining the resistance value of each resistor in the analog grounding resistance module according to the voltage signal and the current detected by the sensor so as to determine the branch where the grounding fault of the bus to be tested is located.
2. The ground fault test circuit of claim 1, wherein the switch control module comprises a first optocoupler unit, a second optocoupler unit, a third optocoupler unit, and a fourth optocoupler unit; the input end of the first photoelectric coupling unit is electrically connected with the first end of the current-limiting resistor module, the first output end of the first photoelectric coupling unit is electrically connected with the controller, and the second output end of the first photoelectric coupling unit is electrically connected with the input end of the second photoelectric coupling unit; the control end of the second photoelectric coupling unit is electrically connected with the controller, the output end of the second photoelectric coupling unit is electrically connected with the input end of the third photoelectric coupling unit, and the output end of the second photoelectric coupling unit is grounded; the first output end of the third photoelectric coupling unit is electrically connected with the input end of the fourth photoelectric coupling unit, and the second output end of the third photoelectric coupling unit is electrically connected with the controller; the output end of the fourth photoelectric coupling unit is electrically connected with the second end of the current-limiting resistor module, and the control end of the fourth photoelectric coupling unit is electrically connected with the controller.
3. The ground fault test circuit of claim 2, wherein each optocoupler unit is provided with a respective optocoupler and triode; the input end and the output end of the photoelectric coupler in the first photoelectric coupling unit are respectively used as the input end and the second output end of the first photoelectric coupling unit, and the first pole of the triode in the first photoelectric coupling unit is used as the first output end of the first photoelectric coupling unit; the input end of the photoelectric coupler in the second photoelectric coupling unit is used as the control end of the second photoelectric coupling unit, the output end of the photoelectric coupler in the second photoelectric coupling unit is grounded, and the first pole and the second pole of the triode in the second photoelectric coupling unit are respectively used as the input end and the output end of the second photoelectric coupling unit; the input end and the output end of the photoelectric coupler in the third photoelectric coupling unit are respectively used as the input end and the first output end of the third photoelectric coupling unit, and the first pole of the triode in the third photoelectric coupling unit is used as the second output end of the third photoelectric coupling unit; the input end of the photoelectric coupler in the fourth photoelectric coupling unit is used as the control end of the fourth photoelectric coupling unit, the output end of the photoelectric coupler in the fourth photoelectric coupling unit is grounded, and the first pole and the second pole of the triode in the fourth photoelectric coupling unit are respectively used as the input end and the output end of the fourth photoelectric coupling unit.
4. A ground fault test circuit according to claim 3, wherein each photo-coupling unit is further provided with a power supply, a second pole of a triode in the first photo-coupling unit is electrically connected to the power supply in the first photo-coupling unit, an input of a photo-coupler in the second photo-coupling unit is electrically connected to the power supply in the second photo-coupling unit, a second pole of a triode in the third photo-coupling unit is electrically connected to the power supply in the third photo-coupling unit, and an input of a photo-coupler in the fourth photo-coupling unit is electrically connected to the power supply in the fourth photo-coupling unit.
5. The ground fault test circuit of claim 3, wherein the first and third optocoupler units are each provided with a resistor and a capacitor, a first pole of a triode in the first optocoupler unit is electrically connected to the resistor and the capacitor in the first optocoupler unit, and a first pole of a triode in the third optocoupler unit is electrically connected to the resistor and the capacitor in the third optocoupler unit.
6. The ground fault test circuit of claim 5, wherein the resistor comprises an adjustable resistor.
7. The ground fault test circuit of claim 1, wherein the analog ground resistance module comprises a first resistance and a second resistance; the first end of the first resistor is electrically connected with the positive electrode of the bus to be tested and serves as the first end of the analog grounding resistor module, the second end of the first resistor is grounded, the first end of the second resistor is electrically connected with the negative electrode of the bus to be tested and serves as the second end of the analog grounding resistor module, and the second end of the second resistor is electrically connected with the second end of the first resistor.
8. The ground fault test circuit of claim 7, wherein the current limiting resistor module comprises a third resistor and a fourth resistor, a first end of the first resistor is electrically connected to one end of the third resistor, the other end of the third resistor is electrically connected to one end of the fourth resistor as the first end of the current limiting resistor module, the other end of the fourth resistor is electrically connected to the second end of the current limiting resistor module, and the first end and the second end of the current limiting resistor module are electrically connected to the input end and one output end of the switch control module, respectively.
9. The ground fault test circuit of claim 1, wherein the analog ground resistance module comprises a first end and a second end, the current limiting resistance module comprises a first end, a second end, a third end and a fourth end, the switch control module comprises an input end, a control end and three output ends, the input end and one of the output ends of the switch control module are respectively electrically connected with the first end and the second end of the current limiting resistance module, the control end of the switch control module is electrically connected with the output end of the controller, the other two output ends of the switch control module are respectively electrically connected with the input end of the controller, and the first end and the second end of the analog ground resistance module are respectively electrically connected with the third end and the fourth end of the current limiting resistance module.
10. The ground fault test circuit of claim 1, wherein the bus to be tested is a direct current bus of a substation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310836785.5A CN116840623A (en) | 2023-07-07 | 2023-07-07 | Ground fault test circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310836785.5A CN116840623A (en) | 2023-07-07 | 2023-07-07 | Ground fault test circuit |
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| Publication Number | Publication Date |
|---|---|
| CN116840623A true CN116840623A (en) | 2023-10-03 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310836785.5A Pending CN116840623A (en) | 2023-07-07 | 2023-07-07 | Ground fault test circuit |
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| Country | Link |
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| CN (1) | CN116840623A (en) |
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2023
- 2023-07-07 CN CN202310836785.5A patent/CN116840623A/en active Pending
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