Device for automatically measuring resistance of GIS (Gas Insulated Switchgear) main loop without dismounting ground wire

Abstract

The utility model provides a device for measuring the resistance of an automatic GIS main loop without dismounting a ground wire. The device is provided with a first test point P1, a second test point P2, a third test point P3, a fourth test point P4 and a fifth test point P5. The measuring device comprises a direct current source, a current sensor, a power supply, a high-current-carrying-capability connecting wire, an ammeter, a voltmeter and a clip-on ammeter. According to the technical scheme, potential safety hazards and operation complexity caused by disassembly of the grounding bar in a traditional measurement method can be avoided, meanwhile, the measurement precision and efficiency are improved, and damage to equipment caused by repeated disassembly of the grounding bar is avoided.

Description

Technical Field

[0001] This utility model relates to the field of GIS equipment technology, and in particular to an automated GIS main circuit resistance measuring device that does not require the grounding wire to be removed. Background Technology

[0002] With the rapid development of power systems, gas-insulated metal-enclosed switchgear (GIS) is widely used in high-voltage power systems due to its advantages such as compact structure, small footprint, safe operation, low installation and maintenance workload, and long maintenance cycle. However, the fully enclosed structure of GIS also brings many challenges, especially in loop resistance measurement. Traditional loop resistance measurement methods, such as the DC voltage drop method, usually require the removal of the grounding busbar, which is not only cumbersome but also may pose safety hazards and even affect the long-term stability of the equipment. Specifically, removing the grounding busbar and grounding switch is not only labor-intensive but also prone to grounding problems. Furthermore, the electric field around the equipment may induce voltage during removal, posing safety risks to workers. In addition, oxide films or stains easily accumulate at the opening and closing points of the grounding switch, increasing contact resistance and affecting the accuracy of the measurement results. Utility Model Content

[0003] In view of this, the purpose of this utility model is to provide a measuring device for the resistance of the main circuit of an automated GIS without removing the grounding wire, which avoids the safety hazards and operational complexity caused by disassembling the grounding busbar in traditional measurement methods, while improving measurement accuracy and efficiency, and avoiding damage to the equipment caused by repeated disassembly of the grounding busbar.

[0004] To achieve the above objectives, this utility model adopts the following technical solution: a device for measuring the resistance of an automated GIS main circuit without removing the grounding wire, wherein the measured GIS main circuit includes the resistance R1 at the outgoing terminal, the resistance R2 of the disconnector switch 2423, the resistance R3 of the circuit breaker 242, and the resistance R of the grounding switch 2426A. 1-1 The resistor R of the grounding switch 2426B 1-2 The resistance R of the grounding switch 2426D 1-3 The resistance R of the grounding switch 2426C 1-4 The first outer casing grounding resistance R connected to the grounding switch 2426A 2-1 The second outer casing grounding resistance R connected to the grounding switch 2426B 2-2 The third outer casing grounding resistance R connected to the grounding switch 2426D 2-3 The fourth outer casing grounding resistor R connected to the grounding switch 2426C 2-4The circuit topology is as follows: the grounding busbar is connected to the GIS casing, and the grounding switch is connected to the grounding busbar to achieve grounding; a first test point P1, a second test point P2, a third test point P3, a fourth test point P4, and a fifth test point P5 are set; the first test point P1 is set at the input terminal of resistor R1 at the outgoing line, and the second test point P2 is set at the resistor R of grounding switch 2426A. 1-1 With the first casing grounding resistance R 2-1 Between, the third test point P3 is set at the resistor R of the grounding switch 2426B. 1-2 With the second housing grounding resistance R 2-2 Between, the fourth test point P4 is set at the resistor R of the grounding switch 2426. 1-3 With the third casing grounding resistance R 2-3 Between, the fifth test point P5 is set at the resistor R of the grounding switch 2426C. 1-4 Fourth casing grounding resistance R 2-4 Between; the voltages at the first test point P1, the second test point P2, the third test point P3, the fourth test point P4, and the fifth test point P5 are the first voltage V1, the second voltage V2, the third voltage V3, the fourth voltage V4, and the fifth voltage V5; let the resistance R1 flowing into the outgoing line and the resistance R of the grounding switch 2426A be... 1-1 The resistor R of the grounding switch 2426B 1-2 The resistance R of the grounding switch 2426D 1-3 The resistance R of the grounding switch 2426C 1-4 The currents are respectively the first current I1, the second current I2, the third current I3, the fourth current I4, and the fifth current I5; the measuring device includes a DC current source, a current sensor, a power supply, a high current-carrying capacity connecting wire, an ammeter, a voltmeter, and a clamp ammeter; the DC current source is connected to the GIS main circuit, and the ammeter and voltmeter are connected to the GIS main circuit; the ammeter measures the current values ​​of the first current I1, the second current I2, the third current I3, the fourth current I4, and the fifth current I5; the voltmeter measures the voltage values ​​of the first voltage V1, the second voltage V2, the third voltage V3, the fourth voltage V4, and the fifth voltage V5.

[0005] In a preferred embodiment, the DC current source is specifically a current source that outputs up to 400A of DC current.

[0006] In a preferred embodiment, the current sensor reduces the measured current signal by a factor of 2500.

[0007] In a preferred embodiment, the power supply is specifically a power supply that outputs ±15V DC voltage.

[0008] In a preferred embodiment, the high current-carrying capacity connection line has a current-carrying capacity greater than 400A.

[0009] In a preferred embodiment, the ammeter and voltmeter are specifically a six-digit display ammeter and a six-digit display voltmeter, respectively.

[0010] Compared with existing technologies, this invention has the following advantages: It eliminates the need to disassemble the grounding busbar, avoiding the safety hazards and potential damage to equipment caused by repeated disassembly of grounding wires in traditional methods, thus improving the safety of the testing process and ensuring the long-term stability of the equipment. It improves measurement accuracy: By combining a high-current excitation source with a precision current sensor, this invention can accurately measure current and voltage, making the calculation results of loop resistance more accurate and reliable, significantly improving measurement accuracy. It simplifies the operation process: Through automated data acquisition, real-time calculation, and report generation, this invention simplifies the testing operation process, reduces manual intervention, saves operation time, effectively reduces human error, and improves overall work efficiency. It enhances safety and efficiency: By employing non-contact measurement technology and high-precision equipment, this invention improves work efficiency while ensuring measurement safety, and is particularly suitable for high-current loop resistance testing, meeting the needs of high-precision electrical measurements. In summary, this invention not only improves the accuracy, efficiency, and safety of GIS equipment loop resistance measurement, but also optimizes the testing process, reduces equipment wear, and provides more reliable technical support for the maintenance of GIS equipment in power systems. Attached Figure Description

[0011] Figure 1 This is a connection block diagram of the GIS equipment loop resistance testing device according to a preferred embodiment of the present invention;

[0012] Figure 2 This is a flowchart of the loop resistance measurement process according to a preferred embodiment of the present invention;

[0013] Figure 3 This is a cross-sectional view of the GIS structure of a preferred embodiment of the present invention;

[0014] Figure 4 This is a circuit topology diagram of a preferred embodiment of the present invention;

[0015] Figure 5 This is a topology diagram of the secondary test circuit of a preferred embodiment of the present invention. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0018] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0019] A device for measuring the resistance of an automated GIS main circuit without removing the grounding wire, referenced. Figure 1-5 The measured GIS main circuit includes the resistance R1 at the outgoing terminal, the resistance R2 of the disconnector switch 2423, the resistance R3 of the circuit breaker 242, and the resistance R of the grounding switch 2426A. 1-1 The resistor R of the grounding switch 2426B 1-2 The resistance R of the grounding switch 2426D 1-3 The resistance R of the grounding switch 2426C 1-4 The first outer casing grounding resistance R connected to the grounding switch 2426A 2-1 The second outer casing grounding resistance R connected to the grounding switch 2426B 2-2 The third outer casing grounding resistance R connected to the grounding switch 2426D 2-3 The fourth outer casing grounding resistor R connected to the grounding switch 2426C 2-4 The circuit topology is as follows: the grounding busbar is connected to the GIS casing, and the grounding switch is connected to the grounding busbar to achieve grounding; a first test point P1, a second test point P2, a third test point P3, a fourth test point P4, and a fifth test point P5 are set; the first test point P1 is set at the input terminal of resistor R1 at the outgoing line, and the second test point P2 is set at the resistor R of grounding switch 2426A. 1-1 With the first casing grounding resistance R 2-1 Between, the third test point P3 is set at the resistor R of the grounding switch 2426B. 1-2 With the second housing grounding resistance R 2-2 Between, the fourth test point P4 is set at the resistor R of the grounding switch 2426. 1-3 With the third casing grounding resistance R 2-3 Between, the fifth test point P5 is set at the resistor R of the grounding switch 2426C. 1-4 Fourth casing grounding resistance R 2-4Between; the voltages at the first test point P1, the second test point P2, the third test point P3, the fourth test point P4, and the fifth test point P5 are the first voltage V1, the second voltage V2, the third voltage V3, the fourth voltage V4, and the fifth voltage V5; let the resistance R1 flowing into the outgoing line and the resistance R of the grounding switch 2426A be... 1-1 The resistor R of the grounding switch 2426B 1-2 The resistance R of the grounding switch 2426D 1-3 The resistance R of the grounding switch 2426C 1-4 The currents are respectively the first current I1, the second current I2, the third current I3, the fourth current I4, and the fifth current I5;

[0020] The measuring device includes a DC current source, a current sensor, a power supply, high current-carrying capacity connecting wires, an ammeter, a voltmeter, and a clamp ammeter;

[0021] This invention employs a high-precision current source capable of stably outputting up to 400A of DC current, meeting the requirement of at least 100A for main circuit testing of GIS equipment. The larger current helps to break down the oxide film at the switch contacts, thereby reducing contact resistance and improving measurement accuracy. This current source maintains a stable output, ensuring current stability during testing and avoiding measurement errors caused by current fluctuations.

[0022] Current sensor

[0023] The system is equipped with a high-precision current sensor that can reduce the measured current signal by 2,500 times, making the measurement data more accurate and facilitating data processing and subsequent analysis.

[0024] Power supply (±15V)

[0025] The testing system includes a power supply that outputs ±15V DC voltage, specifically designed to provide a stable voltage for the voltmeter, ensuring the accuracy of voltage measurements and avoiding errors caused by power supply instability.

[0026] High current carrying capacity connection cable

[0027] The system is equipped with line connection cables with a current carrying capacity greater than 400A for connecting current sources, circuits, and other test equipment. This ensures that the lines are not affected by overheating or damage when high currents pass through them.

[0028] Ammeter and voltmeter (six-digit display)

[0029] The system uses precision six-digit ammeters and voltmeters to display the current and voltage in the circuit, respectively. These instruments provide high-precision measurement data, supporting subsequent circuit resistance calculations.

[0030] Clamp-on ammeter

[0031] This invention also uses a clamp-on ammeter to accurately measure grounding bar current data, which has a non-contact measurement function, ensuring the safety of personnel during the testing process and avoiding electrical hazards during high current testing.

[0032] upper computer and RS485 communication system

[0033] The system transmits test data to the host computer in real time via the RS485 communication protocol. Voltmeters and ammeters are connected to the host computer via RS485 interfaces to ensure efficient and stable data transmission. The host computer system has real-time data monitoring and storage functions, displaying current current and voltage data and calculating loop resistance values. All measurement data is automatically recorded, and test reports are generated by the host computer software, providing complete test results and analysis, and supporting data backup and subsequent retrieval. The host computer and RS485 communication system are common techniques used by those skilled in the art; their circuit connections will not be detailed here.

[0034] The DC current source is connected to the GIS main circuit, and the ammeter and voltmeter are also connected to the GIS main circuit. The ammeter measures the current values ​​of the first current I1, the second current I2, the third current I3, the fourth current I4, and the fifth current I5. The voltmeter measures the voltage values ​​of the first voltage V1, the second voltage V2, the third voltage V3, the fourth voltage V4, and the fifth voltage V5.

[0035] This testing device achieves automated measurement of GIS main circuit resistance without disconnecting the grounding wire through the following steps:

[0036] (1) Power off and voltage testing

[0037] First, disconnect the power supply to the GIS equipment via the electrical control system or circuit breaker to ensure no current flows through the circuit. Then, use a high-voltage detector that meets safety standards to test the GIS equipment for voltage, ensuring the equipment is de-energized and there is no induced voltage in the test area. Finally, use a low-voltage tester to confirm again that the equipment terminals are de-energized, ensuring electrical safety.

[0038] (2) Grounding system inspection

[0039] Use a grounding resistance tester to check the grounding system of GIS equipment to ensure that the grounding resistance meets the standard requirements. A grounding current tester can simulate a large current passing through the grounding loop to observe the stability of the grounding system and ensure the normal operation of the loop.

[0040] (3) Select and connect the test equipment

[0041] Connect the high-precision ammeter and voltmeter to the external terminals of the GIS equipment, ensuring good wiring quality and avoiding poor contact. Use a high-precision 400A DC current source connected to the test circuit to provide a stable, high current for testing. Check the insulation condition of the wiring and equipment to prevent current leakage.

[0042] (4) Power on and start the test

[0043] After confirming that all devices are properly connected, start the current source to provide 400A of current to the circuit. Simultaneously, turn on the ammeter and voltmeter to monitor the current and voltage changes in the circuit. The ammeter and voltmeter transmit the test data to the host computer in real time via the RS485 communication protocol for real-time monitoring. Once the current and voltage data in the circuit stabilize, record the stable current and voltage values.

[0044] (5) Loop resistance calculation

[0045] Based on the structural diagram of the GIS equipment, a corresponding impedance matrix is ​​constructed, considering the influence of wiring impedance and external equipment impedance (including inductance, capacitance, etc.) on the loop resistance. Using high-precision computing equipment or software systems, the collected data is automatically processed to calculate the loop resistance value, which is then compared with the equipment design standard value to obtain the final loop resistance test result.

[0046] (6) Result Judgment and Output

[0047] The measured loop resistance value is compared with the equipment design standard value. If the loop resistance value meets the standard range, the test result is passed; if it exceeds the standard value, an automatic alarm is triggered and the abnormal impedance location is marked, prompting the test personnel to check the abnormal loop resistance location. The system will automatically generate a detailed test report, recording the equipment used during the test, the measured data, and the calculated loop resistance results. The test data and report can be stored and backed up for easy subsequent analysis and retrieval.

[0048] Taking a typical double-busbar GIS as an example, this invention details the method for rapidly measuring the resistances of various components in the GIS main circuit without removing the grounding busbar. A cross-sectional view of this typical double-busbar GIS structure is shown below. Figure 1As shown in the diagram, 242 represents the bus tie circuit breaker, 2421, 2422, and 2423 are the disconnecting switches on the bus side, and 2426A, 2426B, 2426C, and 2426D are the grounding switches. CT is a current transformer. Since the busbar, circuit breaker, disconnecting switch, and grounding switch are all enclosed within the GIS tank, direct contact or measurement is not possible. Testing can only be performed on the outgoing terminals and the exposed parts connecting the grounding switches to the grounding busbar. Specifically, this typical double-busbar GIS has five test points: P1 on the outgoing side, and P2, P3, P4, and P5 on the exposed parts connecting the grounding switches A, B, C, and D to the grounding busbar. These test points are connected to key equipment inside the GIS via external wiring, enabling resistance measurements of the circuit breakers, disconnecting switches, and grounding switches.

[0049] To more intuitively demonstrate the circuit structure of this GIS, Figure 1 The structural cross-sectional diagram is simplified into a circuit topology diagram, such as... Figure 2 As shown. When measuring the main circuit resistance, it is necessary to open the disconnect switches 2421 and 2422 on bus I and bus II sides, therefore they are not shown in the circuit topology diagram. R1 represents the resistance at the outgoing terminal, R2 represents the resistance of disconnect switch 2423, R3 represents the resistance of circuit breaker 242, and R... 1-1 R 1-2 R 1-3 R 1-4 These represent the resistances of grounding switches 2426A, 2426B, 2426D, and 2426C, respectively. The grounding busbar is connected to the GIS casing, and the grounding switches achieve grounding by connecting to the grounding busbar. Therefore, there is also a casing grounding resistance, R, between the grounding switch and the actual grounding. 2-1 R 2-2 R 2-3 R 2-4 These represent the grounding resistance of the outer casing connected to grounding switches 2426A, 2426B, 2426D, and 2426C, respectively.

[0050] When giving Figure 2 The circuit topology diagram shows a 400A DC power source connected at point P1 for a single excitation source power-on test. Test points are P1, P2, P3, P4, and P5. High-precision voltmeters are connected to these five test points to measure voltage data. The voltages corresponding to P1, P2, P3, P4, and P5 are set as V1, V2, V3, V4, and V5, respectively. A six-digit high-precision ammeter is connected to measure the current value. The current flowing into R1 and R2 is set as follows: 1-1 R 1-2 R 1-3 R 1-4 Let the currents be I1, I2, I3, I4, and I5. From this, we can derive the following set of loop current equations for each test point:

[0051] I1×R1-I2×R 1-1 =V1-V2 (1)

[0052] I2×R 1-1 +(I1+I2)×R2-I3×R 1-2 =V2-V3 (2)

[0053] I3×R 1-2 +(I1+I2+I3)×R3-I4×R 1-3 =V3-V4 (3)

[0054] I4×R 1-3 -I5×R 1-4 =V4-V5 (4)

[0055] The above system of loop current equations has four valid equations, and the unknowns are R1, R2, R3, and R. 1-1 R 1-2 R 1-3 and R 1-4 There are a total of 7 unknowns, and it is clear that the current equations for this loop have no solution. To solve for these 7 unknowns, this invention proposes modifying the circuit topology to perform a secondary excitation source energization test. The modified circuit topology is shown below. Figure 3 As shown, R is connected using a switch mechanism box. 1-4 The grounding switch represented by 2426C is opened.

[0056] When the secondary excitation source is powered on for testing, the voltages corresponding to P1, P2, P3, P4, and P5 are V1', V2', V3', V4', and V5', respectively, flowing into R1 and R2. 1-1 R 1-2 R 1-3 R 1-4 The currents are I1', I2', I3', I4', and I5', and the loop current equations for the secondary excitation source test can be listed as follows:

[0057] I1'×R1-I'2×R 1-1 =V1'-V2' (5)

[0058] I'2×R 1-1 +(I1'+I'2)×R2-I3'×R 1-2 =V2'-V3' (6)

[0059] I3'×R 1-2 +(I1'+I'2+I3')×R3-I'4×R 1-3 =V3'-V4' (7)

[0060] Solve the simultaneous equations (1), (2), (3) and (5), (6), (7), and the unknowns are R1, R2, R3, and R. 1-1 R 1-2 R 1-3 There are 6 equations in total, and 6 of them are valid, meaning the system of equations has a solution, and a unique solution. The obtained R is then used to solve the system. 1-3 Substituting into equation (4), we can obtain R. 1-4 The solution.

[0061] The data from the voltmeter and ammeter tests can be transmitted to the host computer in real time via the RS485 communication protocol after stabilization. Upon receiving the data, the host computer program saves the test results and processes the data according to preset calculation equations (such as equations (1), (2), (3), (5), (6), and (7)) to calculate the loop impedance value. The calculated impedance value is compared with the equipment's standard value. If the difference exceeds a predetermined range, the host computer will automatically issue an alarm to alert the tester to the abnormal situation. Through this automated process, the present invention can quickly and accurately test the loop impedance, ensuring the real-time performance and accuracy of the test, and effectively improving test efficiency and equipment safety.

Claims

1. A device for measuring the resistance of an automated GIS main circuit without removing the grounding wire, wherein the measured GIS main circuit includes the resistance R1 at the outgoing terminal, the resistance R2 of the disconnecting switch (2423), the resistance R3 of the circuit breaker (242), and the resistance R of the grounding switch A. 1-1 The resistance R of grounding switch B 1-2 The resistance R of the grounding switch 1-3 The resistance R of the grounding switch C 1-4 The first outer casing grounding resistance R connected to the grounding switch A 2-1 The second outer casing grounding resistance R connected to grounding switch B 2-2 The third outer casing grounding resistance R connected to the grounding switch is 2-3 The fourth outer casing grounding resistance R connected to the grounding switch C 2-4 The circuit topology is as follows: the grounding busbar is connected to the GIS casing, and the grounding switch is connected to the grounding busbar to achieve grounding; its characteristic is that... The first test point P1, the second test point P2, the third test point P3, the fourth test point P4 and the fifth test point P5 are set; the first test point P1 is set at the access end of the resistor R1 of the outgoing line end, the second test point P2 is set at the resistor R 1-1 between the first shell grounding resistor R 2-1 , the third test point P3 is set at the resistor R 1-2 between the second shell grounding resistor R 2-2 , the fourth test point P4 is set at the resistor R 1-3 between the third shell grounding resistor R 2-3 , the fifth test point P5 is set at the resistor R 1-4 between the fourth shell grounding resistor R 2-4 ; the voltage of the first test point P1, the second test point P2, the third test point P3, the fourth test point P4 and the fifth test point P5 is the first voltage V1, the second voltage V2, the third voltage V3, the fourth voltage V4 and the fifth voltage V5; the current flowing into the resistor R1 of the outgoing line end, the resistor R 1-1 of the ground knife switch A, the resistor R 1-2 of the ground knife switch B, the resistor R 1-3 of the ground knife switch D and the resistor R 1-4 of the ground knife switch C is the first current I1, the second current I2, the third current I3, the fourth current I4 and the fifth current I5 respectively; the measuring device comprises a direct current source, a current sensor, a power supply, a high current capacity connecting line, an ammeter, a voltmeter and a clamp-on ammeter; The direct current source is connected with the GIS main circuit, and the ammeter and the voltmeter are connected with the GIS main circuit; the ammeter measures the current values of the first current I1, the second current I2, the third current I3, the fourth current I4 and the fifth current I5; and the voltmeter measures the voltage values of the first voltage V1, the second voltage V2, the third voltage V3, the fourth voltage V4 and the fifth voltage V5.

2. The device for measuring the resistance of the main circuit of the GIS without disconnecting the ground wire according to claim 1, characterized in that, The direct current source is specifically a current source outputting direct current of up to 400A.

3. The device for measuring the resistance of the main circuit of the GIS without disconnecting the ground wire according to claim 1, characterized in that, The current sensor reduces the measured current signal by 2500 times.

4. The device for measuring the resistance of the main circuit of the GIS without disconnecting the ground wire according to claim 1, characterized in that, The power supply is specifically a power supply outputting direct voltage of ±15V.

5. The device for measuring the resistance of the main circuit of the GIS without disconnecting the ground wire according to claim 1, characterized in that, The high current-carrying capacity connection line has a current-carrying capacity greater than 400A.

6. The device for measuring the resistance of the main circuit of the GIS without disconnecting the ground wire according to claim 1, characterized in that, The ammeter and the voltmeter are specifically a six-digit digital ammeter and a six-digit digital voltmeter, respectively.

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