Loop resistance multi-mode test method and application

Abstract

The invention relates to a loop resistance multi-mode test method and application, a host, a test line and at least one clamp meter are included, and the method comprises the following steps that a circuit breaker is located at a switching-on position, and disconnecting switches on the two sides of the circuit breaker are located at grounding positions; corresponding test wire connection is completed based on a four-wire system direct current voltage drop method, and testing is carried out; the host power supply adopts a constant-current voltage-limiting mode, the output current can be adjusted according to requirements, and constant large-current power supply output is ensured; the host adopts a large current source based on a phase-shifted full-bridge circuit to ensure that the current flowing through the tested equipment after three-phase shunt and earth screen shunt meets the test standard requirement; the clamp meter is clamped on a tested loop, and a corresponding test mode on the host is selected according to test requirements; a loop resistance calculation module in the host calculates the actual value of the loop resistance according to the clamp meter return data; the device has the advantages of simplicity in operation, no need of disassembling a ground wire, high working efficiency, multiple test modes and high safety coefficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of loop resistance testing, and in particular relates to a loop resistance multi-mode testing method and application. Background Art

[0002] At present, when conducting circuit breaker loop resistance test, it is necessary to change the safety measures and untie the grounding point on one side of the circuit breaker. On the one hand, it is necessary to report to the dispatcher, and after approval, the operating personnel will cooperate to remove the safety measures on one side of the work site, and then restore them before the end of the work, which increases the workload and prolongs the working time and equipment power outage time. On the other hand, after the safety measures are changed, the grounding point on one side of the circuit breaker is released, which poses a safety risk, especially for the circuit breaker inside the GIS. The distance between the break points is very close, and the safety risk of untie the grounding point on one side is extremely high. For the circuit resistance test of circuit breakers of 220kV and above, the primary equipment is high and the wiring is complex, and the circuit resistance test An elevated vehicle is required to perform a drain line connection. After the safety measures are changed, the induced electricity of the equipment accessories is stronger, which greatly increases the personal risk. In addition, for 220 kV bus-coupled GIS circuit breakers, a section of 220 kV bus needs to be stopped during the loop resistance test, which has high grid and operation risks. For 330 kV and above GIS circuit breakers with two-thirds connection, the main transformer / busbar / outgoing line needs to be stopped during the loop resistance test, which has high grid and operation risks. Therefore, it is very necessary to provide a loop resistance multi-mode testing method and application that is simple to operate, does not require disassembly of the ground wire, has high work efficiency, multiple test modes, and a high safety factor. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a loop resistance multi-mode testing method and application that is simple to operate, does not require disassembly of the ground wire, has high work efficiency, has multiple test modes, and has a high safety factor.

[0004] The object of the present invention is achieved as follows: a loop resistance multi-mode testing method includes a host, a test line and at least one clamp meter, the method comprising the following steps:

[0005] Step 1: Place the circuit breaker under test in the closed position and the knife switches on both sides in the grounded position;

[0006] Step 2: Complete the corresponding test line connections based on the four-wire DC voltage drop method and perform the test;

[0007] Step 3: The host power supply adopts constant current and voltage limiting mode. The output current can be adjusted according to demand to ensure constant high current power output.

[0008] Step 4: The host uses a large current source based on a phase-shifted full-bridge circuit to ensure that the current flowing through the device under test after three-phase shunting and ground grid shunting meets the test standard requirements;

[0009] Step 5: Place the clamp meter on the circuit to be tested and select the corresponding test mode on the host according to the test requirements;

[0010] Step 6: The loop resistance calculation module inside the host calculates the actual value of the loop resistance based on the data returned by the clamp meter.

[0011] There are four test lines, including two voltage lines and two current lines; the clamp meter is a DC clamp meter with a measurement accuracy within 2%; wireless data transmission is adopted between the clamp meter and the host.

[0012] The host power supply in step 3 supports the multi-machine parallel function, and the maximum output current of the host power supply is 500A.

[0013] In the present invention, for the loop resistance test of a 1000 kV circuit breaker, the test current flowing through the main loop must be no less than 300 A. Since the resistance of the main loop is much lower than the loop resistance flowing through the ground grid, a 500 A constant current source is used.

[0014] The phase-shifted full-bridge circuit in step 4 includes a driving circuit, a sampling circuit, a protection circuit, a communication circuit and a controller minimum system; wherein the protection circuit includes an input voltage overvoltage protection circuit, a primary current overcurrent protection circuit, an output voltage overvoltage protection circuit, an output current overcurrent protection circuit, an over-temperature protection circuit, a protection latch circuit and a protection coding circuit.

[0015] The host test mode in step 5 includes a direct test mode, a unilateral shunt mode, a bilateral shunt mode, and a multilateral shunt mode.

[0016] In the direct measurement mode, a clamp meter is placed on phase A to measure the loop resistance of phase A. The test formula is: Where R x is the loop resistance; V is the voltage across the measured loop; I1 is the current of phase A.

[0017] In the unilateral shunt mode, a clamp meter is connected to the ground bus of phase A. The current measured by the clamp meter is transmitted back to the host. The loop resistance test module inside the host calculates the loop resistance value of phase A. The test formula is: Where I1 is the current of phase A; I is the total current.

[0018] The bilateral shunt mode is used to test the loop resistance of phase B. Two clamp meters are respectively clamped to the grounding bars of phases A and C. The current measured by the clamp meters is transmitted back to the host. The loop resistance test module inside the host calculates the loop resistance value of phase B. The test formula is: Where I1 is the current of phase A; I2 is the current of phase C.

[0019] The multilateral shunt mode is used to test the situation where there is multi-terminal shunt. Multiple clamp meters are clamped on the grounding bars of the corresponding phases. The current measured by the clamp meters is transmitted back to the host. The loop resistance test module inside the host calculates the loop resistance value of the corresponding phase. The test formula is:

[0020] An application of loop resistance multi-mode testing includes applying the above-mentioned loop resistance multi-terminal grounding testing method to loop resistance testing of circuit breakers, GIS / GIL, and disconnectors.

[0021] Beneficial effects of the present invention: The present invention provides a multi-mode testing method and application for loop resistance. During the operation of disassembling and assembling the grounding bus, there is a risk of falling from a height. When disassembling and assembling the grounding bus in a limited working space, collisions are likely to cause equipment damage and personal injury. During use, the present invention adopts multi-terminal grounding technology to ensure stable equipment operation, reduce the operation of disassembling and assembling the grounding bus, and avoid the risk of injury to workers such as falling from a height, colliding with equipment, and being hit by tools during the long-term operation of disassembling and assembling the grounding bus, thereby protecting equipment and personal safety very well; the present invention can save working time, improve work efficiency, and eliminate induced electricity during the entire testing process to ensure personal safety; the present invention adopts multi-mode testing technology, which can enhance applicability and promotion value in a larger range. The multi-mode measurement of the present invention, in a dual-end mode, faces a wider range of objects and can basically cover all existing scenarios. The present invention greatly reduces the grid risk and operation risk, realizes reduction first and then control, and effectively improves power supply reliability; the present invention has the advantages of simple operation, no need to disassemble the ground wire, high work efficiency, multiple test modes, and high safety factor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the clamp meter direct measurement mode of the present invention.

[0023] Figure 2 Schematic diagram of the unilateral diversion mode of the present invention.

[0024] Figure 3 Schematic diagram of the bilateral shunt mode of the present invention.

[0025] Figure 4 Schematic diagram of the multilateral diversion mode of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the embodiments and / or drawings.

[0027] Example 1

[0028] like Figure 1-4A multi-mode loop resistance test method is shown, comprising a host, test leads, and at least one clamp meter; wherein the test leads are four, including two voltage leads and two current leads; the clamp meter is a DC clamp meter with a measurement accuracy within 2%; wireless data transmission is used between the clamp meter and the host; the method comprises the following steps:

[0029] Step 1: Place the circuit breaker under test in the closed position and the knife switches on both sides in the grounded position;

[0030] Step 2: Use Ohm's law and the four-wire DC voltage drop method to connect the corresponding test wires and perform the test.

[0031] Step 3: The host power supply adopts constant current and voltage limiting mode. The output current can be adjusted according to demand to ensure constant high current power output.

[0032] In the present invention, the host power supply supports the multi-machine parallel function, and the maximum output current of the host power supply is 500A.

[0033] Step 4: The host uses a large current source based on a phase-shifted full-bridge circuit to ensure that the current flowing through the device under test after three-phase shunting and ground grid shunting meets the test standard requirements;

[0034] In the present invention, the phase-shifted full-bridge circuit includes a driving circuit, a sampling circuit, a protection circuit, a communication circuit and a controller minimum system; wherein the protection circuit includes an input voltage overvoltage protection circuit, a primary current overcurrent protection circuit, an output voltage overvoltage protection circuit, an output current overcurrent protection circuit, an overtemperature protection circuit, a protection latch circuit and a protection coding circuit.

[0035] In a specific implementation method that can be realized, ① sampling circuit: the load is a resistive load, the output adopts a voltage-limited constant current mode, and the output voltage and output current must be sampled for control.

[0036] ② Protection circuit: To improve system reliability, corresponding protection circuits are designed for the voltage and current at key points of the system, including: input voltage overvoltage protection, primary current overcurrent protection, output voltage overvoltage protection, output current overcurrent protection, and overtemperature protection. Taking the overtemperature protection circuit as an example, when the temperature sampling signal is higher than 2.69V or lower than 0.38V, high and low temperature protection will occur, and the corresponding temperature range is -40℃ and +90℃;

[0037] When the system is protected, especially hardware protection, a vicious cycle of shutdown after protection and exiting protection after shutdown is not allowed to occur. For this reason, a protection latch circuit is required. When hardware protection occurs, the system shuts down; first, the protection signal is latched to prevent the problem of protection and exiting protection back and forth. At the same time, the signal is encoded and reported to the controller for identification, and the protection event is reported through the human-machine interface.

[0038] ③ Minimum controller system: The controller of the power module uses TMS320F28335, which has a clock frequency of up to 150MHz, 12-channel PWM, 16-channel ADC, and rich IO pins, making it very suitable for controlling switching power supplies.

[0039] Step 5: Place the clamp meter on the circuit to be tested and select the corresponding test mode on the host according to the test requirements;

[0040] In the present invention, the host test mode includes a direct test mode, a unilateral shunt mode, a bilateral shunt mode and a multilateral shunt mode.

[0041] ① In direct measurement mode, use a clamp meter to clamp on phase A, such as Figure 1 As shown, the clamp meter number is Q1, which can test the loop resistance value of phase A. The test formula is: Where R x is the loop resistance; V is the voltage across the measured loop; I1 is the current of phase A.

[0042] In a specific implementation method that can be realized, the loop resistance of phase B and phase C can also be tested in direct measurement mode. The specific operation is the same as the loop resistance test of phase A. The difference is that during the test, you only need to clamp the clamp meter on the corresponding phase B or phase C to test the loop resistance value of phase B or phase C according to the above formula. At this time, I1 in the formula represents the current of phase B or phase C.

[0043] ② In the single-side shunt mode, use a clamp meter to clamp the grounding bar of phase A. Figure 2 As shown in the figure, the clamp meter is numbered Q1. The current measured by the clamp meter is transmitted back to the host. The loop resistance test module inside the host calculates the loop resistance value of phase A. The test formula is: Where I1 is the current of phase A; I is the total current.

[0044] In a feasible specific implementation, when the direct measurement mode is not satisfied, the unilateral shunt mode can be used to test the loop resistance value of phase A, and the specific operation is as described above; the same method can be used for phase C, and the loop resistance value of phase C is measured according to the above formula. At this time, I1 in the formula represents the current of phase C; and for phase B, there is shunt on both sides, so the bilateral shunt mode needs to be considered.

[0045] ③ The bilateral shunt mode is used to test the resistance of the B-phase loop. Two clamp meters are used to clamp onto the grounding bars of phases A and C respectively. Figure 3 As shown in the figure, the clamp meters are numbered Q1 and Q2 respectively. The current measured by the clamp meter is transmitted back to the host. The loop resistance test module inside the host calculates the loop resistance value of phase B. The test formula is: Where I1 is the current of phase A; I2 is the current of phase C.

[0046] In a feasible specific implementation, the unilateral shunt mode of phase B cannot be accurately tested, and the bilateral shunt mode needs to be considered. Two clamp meters Q1 and Q2 are configured and clamped on the grounding buses of phases A and C. The measured current is transmitted back to the host. The current value is subtracted from the total current in the internal algorithm of the host to obtain the loop resistance value of phase B. The test formula is as described above.

[0047] ④Multi-side shunt mode is used to test the situation where there is multi-terminal shunt. Multiple clamp meters are used to be clamped on the grounding bus of the corresponding phases. Figure 4 As shown in the figure, the clamp meters are numbered Q1, Q2, ..., Qn. The current measured by the clamp meter is transmitted back to the host computer. The loop resistance test module inside the host computer calculates the loop resistance value of the corresponding phase. The test formula is:

[0048] In a feasible embodiment, in the case of multi-terminal shunt, a multilateral shunt mode needs to be considered. Multiple clamp meters Q1, Q2, ..., Qn are configured and connected to the ground bus corresponding to A. The measured current is transmitted back to the host. The current value is subtracted from the total current in the host's internal algorithm to obtain the loop resistance value of a certain phase. The test formula is as described above.

[0049] Step 6: The loop resistance calculation module inside the host calculates the actual value of the loop resistance based on the data returned by the clamp meter.

[0050] The present invention provides a multi-mode test method and application for loop resistance. In the operation of disassembling and assembling the grounding busbar, there is a risk of falling from a height. When disassembling and assembling the grounding busbar in a limited working space, collisions are likely to cause equipment damage and personal injury. In use, the present invention adopts multi-terminal grounding technology to ensure stable equipment operation, reduce the operation of disassembling and assembling the grounding busbar, and avoid the risk of injury to workers such as falling from a height, colliding with equipment, and being hit by tools during the long operation of disassembling and assembling the grounding busbar, which can well protect equipment and personal safety. The present invention can save working time and improve work efficiency. In the loop resistance test of the (GIS) circuit breaker, disassembling and assembling the grounding copper busbar is a time-consuming and labor-intensive operation. The present invention uses multi-terminal grounding technology to avoid this operation, which will greatly reduce the labor intensity of the work and improve work efficiency. Efficiency; if the traditional test method is used to conduct a loop resistance test on the tested circuit breaker, the grounding copper busbar on one side of the tested circuit breaker needs to be disconnected. However, since other equipment are energized, when the grounding copper busbar of one of the grounding switches is disconnected, there is a possibility that the energized equipment will generate induced electricity on the tested circuit breaker through a single disconnector break, threatening the personal safety of the staff. However, the present invention can eliminate the induced electricity during the entire test process and ensure personal safety; the present invention adopts multi-mode testing technology, which can enhance applicability and promotion value to a larger extent. The multi-terminal grounding and multi-mode measurement of the present invention, in the dual-terminal mode, are applicable to a wider range of objects and can basically cover all existing scenarios; the present invention has the advantages of simple operation, no need to disassemble the ground wire, high work efficiency, multiple test modes, and high safety factor.

[0051] Example 2

[0052] like Figure 1-4 As shown, an application of loop resistance multi-mode testing includes applying the above-mentioned loop resistance multi-terminal grounding testing method to loop resistance testing of circuit breakers, GIS / GIL, and disconnectors.

[0053] The present invention provides a multi-mode test method and application for loop resistance. In the operation of disassembling and assembling the grounding busbar, there is a risk of falling from a height. When disassembling and assembling the grounding busbar in a limited working space, collisions are likely to cause equipment damage and personal injury. In use, the present invention adopts multi-terminal grounding technology to ensure stable equipment operation, reduce the operation of disassembling and assembling the grounding busbar, and avoid the risk of injury to workers such as falling from a height, colliding with equipment, and being hit by tools during the long operation of disassembling and assembling the grounding busbar, which can well protect equipment and personal safety. The present invention can save working time and improve work efficiency. In the loop resistance test of the (GIS) circuit breaker, disassembling and assembling the grounding copper busbar is a time-consuming and labor-intensive operation. The present invention uses multi-terminal grounding technology to avoid this operation, which will greatly reduce the labor intensity of the work and improve work efficiency. Efficiency; if the traditional test method is used to conduct a loop resistance test on the tested circuit breaker, the grounding copper busbar on one side of the tested circuit breaker needs to be disconnected. However, since other equipment are energized, when the grounding copper busbar of one of the grounding switches is disconnected, there is a possibility that the energized equipment will generate induced electricity on the tested circuit breaker through a single disconnector break, threatening the personal safety of the staff. However, the present invention can eliminate the induced electricity during the entire test process and ensure personal safety; the present invention adopts multi-mode testing technology, which can enhance applicability and promotion value to a larger extent. The multi-terminal grounding and multi-mode measurement of the present invention, in the dual-terminal mode, are applicable to a wider range of objects and can basically cover all existing scenarios; the present invention has the advantages of simple operation, no need to disassemble the ground wire, high work efficiency, multiple test modes, and high safety factor.

Claims

1. A multi-mode loop resistance test method, comprising a host, test leads, and at least one clamp meter, characterized in that: The method comprises the following steps: Step 1: Place the circuit breaker under test in the closed position and the knife switches on both sides in the grounded position; Step 2: Complete the corresponding test line connections based on the four-wire DC voltage drop method and perform the test; Step 3: The host power supply adopts constant current and voltage limiting mode. The output current can be adjusted according to demand to ensure constant high current power output. Step 4: The host uses a large current source based on a phase-shifted full-bridge circuit to ensure that the current flowing through the device under test after three-phase shunting and ground grid shunting meets the test standard requirements; Step 5: Place the clamp meter on the circuit to be tested and select the corresponding test mode on the host according to the test requirements; Step 6: The loop resistance calculation module inside the host calculates the actual value of the loop resistance based on the data returned by the clamp meter.

2. A loop resistance multi-mode testing method according to claim 1, characterized in that: There are four test lines, including two voltage lines and two current lines; the clamp meter is a DC clamp meter with a measurement accuracy within 2%; wireless data transmission is adopted between the clamp meter and the host.

3. The loop resistance multi-mode testing method according to claim 2, wherein: The host power supply in step 3 supports the multi-machine parallel function, and the maximum output current of the host power supply is 500A.

4. A loop resistance multi-mode testing method according to claim 3, characterized in that: The phase-shifted full-bridge circuit in step 4 includes a driving circuit, a sampling circuit, a protection circuit, a communication circuit and a controller minimum system; wherein the protection circuit includes an input voltage overvoltage protection circuit, a primary current overcurrent protection circuit, an output voltage overvoltage protection circuit, an output current overcurrent protection circuit, an over-temperature protection circuit, a protection latch circuit and a protection coding circuit.

5. The loop resistance multi-mode testing method according to claim 4, wherein: The host test mode in step 5 includes a direct test mode, a unilateral shunt mode, a bilateral shunt mode, and a multilateral shunt mode.

6. A loop resistance multi-mode testing method according to claim 5, characterized in that: In the direct measurement mode, a clamp meter is placed on phase A to measure the loop resistance of phase A. The test formula is: Where R x is the loop resistance; V is the voltage across the measured loop; I1 is the current of phase A.

7. The loop resistance multi-mode testing method according to claim 5, characterized in that: In the unilateral shunt mode, a clamp meter is connected to the ground bus of phase A. The current measured by the clamp meter is transmitted back to the host. The loop resistance test module inside the host calculates the loop resistance value of phase A. The test formula is: Where I1 is the current of phase A; I is the total current.

8. The loop resistance multi-mode testing method according to claim 5, wherein: The bilateral shunt mode is used to test the loop resistance of phase B. Two clamp meters are respectively clamped to the grounding bars of phases A and C. The current measured by the clamp meters is transmitted back to the host. The loop resistance test module inside the host calculates the loop resistance value of phase B. The test formula is: Where I1 is the current of phase A; I2 is the current of phase C.

9. The loop resistance multi-mode testing method according to claim 5, wherein: The multilateral shunt mode is used to test the situation where there is multi-terminal shunt. Multiple clamp meters are clamped on the grounding bars of the corresponding phases. The current measured by the clamp meters is transmitted back to the host. The loop resistance test module inside the host calculates the loop resistance value of the corresponding phase. The test formula is:

10. A loop resistance multi-terminal grounding test application, characterized by: The application includes applying the loop resistance multi-terminal grounding test method according to any one of claims 1 to 9 to loop resistance testing of circuit breakers, GIS / GIL, and disconnectors.

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