A condition monitoring system and method for a converter transformer single-hydrogen unit

Abstract

This invention provides a condition monitoring system and method for a converter transformer single-hydrogen device, belonging to the technical field of condition monitoring for converter transformer single-hydrogen devices. To address the technical problem that existing condition assessment instruments cannot efficiently and accurately verify the accuracy of single-hydrogen devices, a simulated pipeline is installed in the middle of the side wall of the sealed cylinder, an oil inlet is installed at the lower part of the side wall of the sealed cylinder, and an oil outlet is opened at the bottom of the sealed cylinder. An electric heater and an oil thermometer are also installed on the inner wall of the sealed cylinder. An oil pressure gauge and an air bladder are installed on the inner side of the top of the sealed cylinder. The air bladder is connected to an air pump located outside the sealed cylinder via a pipeline, and a pressure relief port is also provided on the pipeline. This invention ensures controllable oil temperature and pressure during single-hydrogen device assessment, guarantees that the standard oil concentration at the oil inlet is consistent with the oil concentration detected by the single-hydrogen device, and achieves the verification of the accuracy of the single-hydrogen device.

Description

Technical Field

[0001] This invention provides a condition monitoring system and method for a converter transformer single-hydrogen device, belonging to the technical field of condition monitoring for converter transformer single-hydrogen devices. Background Technology

[0002] Converter transformers are typically used for high-power, long-distance DC transmission and serve as the main transmission channel for power grids, playing a vital role in the power system. When overheating or discharge occurs inside the transformer, the initial characteristic is the decomposition of transformer oil, producing characteristic gases such as hydrogen. Therefore, by monitoring the content of characteristic gases such as hydrogen in the oil, the operating status of the transformer can be understood. Experiments show that when transformer oil produces hydrogen, it first accumulates at the top. Therefore, a single hydrogen device is usually installed on the top riser of the converter transformer to monitor the hydrogen content.

[0003] The currently used single-hydrogen devices differ from conventional online oil chromatography monitoring devices (which can monitor 7 characteristic gases, but with a monitoring cycle as short as 1 hour). Although they can only monitor hydrogen, they are widely used in converter transformers due to their small size and short hydrogen monitoring cycle (1 second). However, because the single-hydrogen devices are installed on top of the converter transformer, to ensure the long-term stability and reliability of the monitoring accuracy, it is necessary to periodically shut down the entire station and then disassemble all the single-hydrogen devices for accuracy evaluation. This process is somewhat arbitrary and inefficient. Usually, the disassembled single-hydrogen devices are installed in a miniaturized condition assessment instrument that simulates their normal operating conditions. This instrument is pre-filled with a prepared hydrogen concentration standard oil. However, the current condition assessment instrument cannot simulate the actual oil temperature, oil pressure, and strong oil circulation environment of the single-hydrogen device on the transformer, resulting in unconvincing monitoring and evaluation results. Therefore, there is an urgent need for a precise condition assessment instrument and method for single-hydrogen devices in converter transformers.

[0004] Currently, patent CN118091090A discloses a calibration fixture and method for an online single hydrogen monitoring device in oil, which can simultaneously calibrate single hydrogen sensors of different specifications, greatly improving inspection efficiency. However, this method does not consider oil temperature, oil pressure, and oil circulation, and cannot realistically simulate the actual operating environment of the online single hydrogen monitoring device on a transformer, thus still resulting in unconvincing calibration results. Another patent, CN116754610A, discloses a low-power self-calibrating single hydrogen sensor monitoring method, which achieves self-calibration, high-precision, and low-power hydrogen content monitoring by setting a reference module in the hydrogen sensor. However, the reference module of this method uses a single hydrogen concentration in the oil sample in the cavity, which cannot be changed once installed, and it does not consider the influence of different oil pressures and oil circulation in the cavity and transformer on the monitoring. Therefore, the self-calibration is not convincing.

[0005] Therefore, there is an urgent need to improve the condition assessment instruments for existing converter transformer single-hydrogen devices to ensure the reliability of single-hydrogen device assessment and to achieve accurate and rapid verification of the accuracy of single-hydrogen devices. Summary of the Invention

[0006] To address the technical problem that existing condition assessment instruments cannot efficiently and accurately verify the accuracy of single-hydrogen devices, the present invention provides a condition detection system for a converter transformer single-hydrogen device, comprising a closed cylinder with a circular arc bottom, a single-hydrogen device, a computer, an air pump, and a transformer. Multiple support legs are provided around the outer perimeter of the bottom of the closed cylinder, a simulated pipeline is provided in the middle of the side wall of the closed cylinder, an oil inlet is provided in the lower part of the side wall of the closed cylinder, and an oil outlet is provided at the bottom of the closed cylinder.

[0007] An electric heater and an oil thermometer are also installed on the inner wall of the sealed oil cylinder. The control terminal of the electric heater is connected to the computer via a wire, and the signal output terminal of the oil thermometer is connected to the computer via a wire.

[0008] An oil pressure gauge and an air bladder are installed on the inner side of the top of the closed oil cylinder. The air bladder is connected to an air pump installed on the outside of the closed oil cylinder through a pipeline. A pressure relief port is also provided on the pipeline. The control end of the air pump is connected to a computer through a wire.

[0009] An oil inlet and an exhaust outlet are also provided at the top of the sealed oil cylinder;

[0010] A single hydrogen device sensor is inserted into the simulated pipeline. The simulated pipeline is connected to the single hydrogen device via a metal thread. The signal output terminal of the single hydrogen device is connected to the background monitoring platform via a wire.

[0011] A gas relay lead-down port is provided at the bottom of the transformer. The gas relay lead-down port is connected to the gas relay through a pipeline. The single hydrogen device and the gas relay are connected to the riser provided at the top of the transformer through a tee connector.

[0012] An oil pump is also installed on the outside of the closed oil cylinder, and the control terminal of the oil pump is connected to a computer via a wire.

[0013] One side of the oil pump is connected to a closed oil cylinder near the oil intake port via a pipeline, and the other side of the oil pump is connected to a simulated pipeline via a pipeline.

[0014] The number of support legs is four, and each support leg is evenly distributed and installed on the outer side of the bottom of the closed oil cylinder.

[0015] The simulated pipeline is specifically welded to the side wall of the sealed hydraulic cylinder.

[0016] The electric heater is used to control the oil temperature inside the sealed oil cylinder, and the oil thermometer is used to monitor the oil temperature inside the sealed oil cylinder.

[0017] The airbag is used to control the oil pressure inside the sealed cylinder, and the oil pressure gauge is used to monitor the oil pressure inside the sealed cylinder.

[0018] The background monitoring platform is used to display the monitoring results of the single hydrogen unit.

[0019] Specifically, the sensor for the single-hydrogen device is inserted into the simulated pipeline for detection during condition assessment.

[0020] After the oil pump is connected to the closed oil cylinder and the simulated pipeline through pipelines, it is used to realize oil circulation and ensure that the standard oil concentration at the oil intake port is consistent with the oil concentration detected by the single hydrogen unit.

[0021] The transformer oil temperature during operation is 60℃-90℃.

[0022] A method for detecting the condition of a converter transformer single-hydrogen unit using a condition monitoring system includes the following detection steps:

[0023] Step 1: Periodically extract oil samples from the top of the transformer through the gas relay lead-down port, perform offline chromatographic analysis to obtain the hydrogen content m in the oil, and compare it with the detection result n of the single hydrogen unit on the background monitoring platform at the same time. When (mn) / n is greater than 20%, or |mn| is greater than 5ppm, start the status assessment process of the single hydrogen unit.

[0024] Step 2: Disconnect the single hydrogen unit from the simulation pipeline, open the oil inlet and vent of the oil cylinder, and inject the prepared low-concentration standard oil into the closed oil cylinder until oil comes out of the vent. At this time, close the oil inlet and vent.

[0025] Step 3: The electric heater is operated by computer until the oil temperature gauge reading matches the oil temperature at the top of the transformer. At the same time, the oil pump is operated by computer to inflate the air bladder until the oil pressure gauge reading matches the oil pressure at the top of the transformer, thus realizing the oil circulation between the simulated pipeline and the closed oil cylinder.

[0026] Step 4: After the value monitored by the single hydrogen unit in the background stabilizes at q, take an oil sample from the oil inlet and use offline chromatography to obtain the hydrogen content p in the oil. Then open the pressure relief port and close it after no gas is discharged from the pressure relief port. Open the oil drain port and the exhaust port and close them after no oil is discharged from the oil drain port.

[0027] Step 5: Open the oil inlet and vent of the closed oil cylinder, inject the prepared high-concentration standard oil into the closed oil cylinder until oil comes out of the vent. Close the oil inlet and vent, and repeat steps 3 and 4 to obtain the detection value u and offline analysis value w of the single hydrogen device under high-concentration standard oil.

[0028] Step 6: Calculate the evaluation state L of the single hydrogen unit under low-concentration standard oil. The calculation formula is:

[0029] ;

[0030] The formula for calculating the evaluation state K of a single hydrogen unit under high-concentration standard oil is as follows:

[0031] ;

[0032] The overall condition assessment coefficient D of a single hydrogen unit is calculated using the following formula:

[0033] .

[0034] The beneficial effects of this invention compared to the prior art are as follows: This invention provides a single-hydrogen device status detection system and method for converter transformers. By setting a pressurization module and a heating module on the detection and evaluation device, it can simulate the oil temperature and oil pressure changes of the single-hydrogen device on the operating converter transformer. This ensures that the oil temperature and oil pressure are controllable during the evaluation of the single-hydrogen device. The oil circulation module set in the detection system connects the oil pump to the closed oil cylinder and the simulated pipeline through pipelines to ensure that the standard oil concentration at the oil sampling port is consistent with the oil concentration detected by the single-hydrogen device, thereby realizing the verification of the accuracy of the single-hydrogen device. Attached Figure Description

[0035] The present invention will be further described below with reference to the accompanying drawings:

[0036] Figure 1 This is a schematic diagram of the condition monitoring system for the converter transformer single hydrogen device of the present invention;

[0037] Figure 2 This is a schematic diagram of the installation structure of the single hydrogen device of the present invention on a transformer;

[0038] Figure 3 This is a flowchart of the steps in the method for detecting the state of a single hydrogen device in a converter transformer according to the present invention.

[0039] In the diagram: 1 is a closed oil cylinder, 2 is a simulated pipeline, 3 is an electric heater, 4 is an oil thermometer, 5 is an oil pump, 6 is an oil drain port, 7 is an oil filling port, 8 is an exhaust port, 9 is an oil intake port, 10 is an oil pressure gauge, 11 is a single hydrogen unit, 12 is a gas relay, 13 is a gas relay lead-down port, 14 is a background monitoring platform, 15 is a support leg, 16 is a lifting seat, 17 is a computer, 18 is an airbag, 19 is a pressure relief port, 20 is an air pump, and 21 is a sensor for the single hydrogen unit. Detailed Implementation

[0040] The detection principle of the single hydrogen device in the converter transformer is based on the chemical principle of the reaction between nickel-palladium alloy and hydrogen in the oil, thereby detecting the hydrogen content in the oil. It usually takes ten hours from the time the hydrogen detection value is placed in the oil until it stabilizes. After the detection value stabilizes, it is updated every second. Since the accuracy can only be evaluated during the power outage maintenance of the converter transformer, and the power outage maintenance time is relatively short, the evaluation of all single hydrogen devices 11 by periodically shutting down the power outage is somewhat blind and inefficient. Therefore, there is a need for a highly efficient and accurate condition detection and evaluation system and method to ensure the reliability of the evaluation. This invention can realistically simulate the operating environment of the single hydrogen device 11 on the transformer riser, ensuring the reliability of the single hydrogen device 11 evaluation and realizing accurate and rapid verification of the single hydrogen device 11.

[0041] like Figure 1 As shown, the present invention provides a single-hydrogen device status monitoring system for a converter transformer, comprising a 10L enclosed oil cylinder 1, a simulated pipeline 2, an electric heater 3, an oil thermometer 4, an oil pump 5, an oil drain port 6, an oil filling port 7, an exhaust port 8, an oil intake port 9, an oil pressure gauge 10, a single-hydrogen device 11, a gas relay 12, a gas relay lead-down port 13, a background monitoring platform 14, support legs 15, a lifting base 16, a computer 17, an airbag 18, a pressure relief port 19, an air pump 20, and a single-hydrogen device sensor 21, wherein:

[0042] Simulated pipelines 2 and oil inlets 9 are welded around the center of the enclosed oil cylinder 1. The bottom has an arc-shaped structure with an oil outlet 6 and four supporting legs 15. Heaters 3 and oil thermometers 4 are located inside the oil cylinder 1 to control and monitor the internal oil temperature. The heaters are controlled by a computer 17. An air bladder 18 and an oil pressure gauge 10 are located on the inner wall of the top of the oil cylinder 1 to control and monitor the internal oil pressure. An air pump 20 is located outside the oil cylinder and connected to the air bladder 18 via a pipeline. A pressure relief port 19 is located on the pipeline. The operation of the air pump 20 is computer-controlled. An oil inlet 7 and an exhaust port 8 are located at the top of the oil cylinder 1. During normal operation, the single-hydrogen device 11 and the gas relay 12 are connected to the riser 16 on top of the transformer via a tee. The gas relay lead-down port 13 is connected to the gas relay 12 via a pipeline and is located at the bottom of the transformer. A background monitoring platform 14 displays the monitoring results of the single-hydrogen device 11. During condition assessment, the single-hydrogen device sensor 21 is inserted into the simulated pipeline 2 for detection. The oil pump 5 is controlled by the computer 17 and is connected to the oil cylinder near the oil intake port on one side of the pipeline and to the simulation pipeline on the other side to realize oil circulation and ensure that the standard oil concentration at the oil intake port is consistent with the oil concentration detected by the single hydrogen device 11.

[0043] like Figure 2As shown, during normal operation, the single hydrogen unit 11 and the gas relay 12 are connected to the transformer top riser 16 via a tee. The gas relay lead-down port 13 is connected to the gas relay 12 via a pipeline and is located at the bottom of the transformer. During transformer operation, the transformer oil temperature is generally 60℃-90℃. The oil pressure at the installation location of the single hydrogen unit 11 is affected by the height of the oil conservator. At the same time, due to the forced oil circulation by the converter transformer submersible pump, the hydrogen content in the oil at the single hydrogen unit 11 is basically the same as that in the main body.

[0044] like Figure 3 As shown, the precise state detection method for a single hydrogen converter unit provided by this invention is as follows:

[0045] Step 1: Periodically extract oil samples from the top of the transformer through the gas relay lead-down port 13, perform offline chromatographic analysis to obtain the hydrogen content m in the oil, and compare it with the detection result n of the single hydrogen device 11 on the background monitoring platform 14 at the same time. When (mn) / n is greater than 20% or |mn| is greater than 5ppm, start the status assessment process of the single hydrogen device 11.

[0046] Step 2: Disconnect the single hydrogen device 11 and connect it to the simulation pipeline 2. Open the oil inlet 7 and the exhaust port 8 of the oil cylinder. Inject the prepared low-concentration standard oil into the closed oil cylinder 1 until oil comes out of the exhaust port 8. At this time, close the oil inlet 7 and the exhaust port 8.

[0047] Step 3: Control the operation of the electric heater 3 through the computer 17 until the reading of the oil thermometer 4 is consistent with the oil temperature at the top of the transformer. At the same time, control the operation of the oil pump 5 to inflate the air bag 18 until the reading of the oil pressure gauge 10 is consistent with the oil pressure at the top of the transformer. The oil circulation between the simulated pipeline 2 and the closed oil cylinder 1 is realized by controlling the start of the oil pump 5.

[0048] Step 4: After the value monitored by the single hydrogen device 11 in the background stabilizes at q, an oil sample is drawn from the oil inlet 9. The hydrogen content p in the oil is obtained by offline chromatography analysis. Then, the pressure relief port 19 is opened. After no gas is discharged from the pressure relief port 19, the pressure relief port 19 is closed. The oil outlet 6 and the exhaust port 8 are opened. After no oil is discharged from the oil outlet 6, the oil outlet 6 and the exhaust port 8 are closed.

[0049] Step 5: Open the oil inlet 7 and vent 8 of the closed oil cylinder 1, and inject the prepared high-concentration standard oil into the closed oil cylinder 1 until oil comes out of the vent 8. Close the oil inlet 7 and vent 8, and repeat steps 3 and 4 to obtain the detection value u and offline analysis value w of the single hydrogen device 11 under high-concentration standard oil.

[0050] Step 6: Calculate the evaluation status L of the single hydrogen unit 11 under low-concentration standard oil according to formula (1):

[0051] (1);

[0052] The evaluation state K of the single hydrogen unit 11 under high concentration standard oil is calculated according to formula (2):

[0053] (2);

[0054] The comprehensive state assessment coefficient D of the single hydrogen unit 11 is calculated according to formula (3):

[0055] (3).

[0056] The hydrogen content in low-concentration and high-concentration hydrogen standard oils is usually shown in Table 1 below. They are generally pre-mixed by an oil mixing machine and then introduced into the single-hydrogen unit condition assessment instrument.

[0057] Table 1 Standard oil concentration range

[0058]

[0059] Because the annual power outage maintenance time for converter stations is limited (about one week), each converter station typically has 24 converter transformers, and each converter transformer has a single hydrogen generator 11, resulting in a large amount of data. Since the gas relay 12 and the single hydrogen generator 11 are connected to the transformer top riser via a tee, and are essentially in the same location, this invention employs an offline chromatographic analysis of oil taken from the gas relay lead-down port 13 and compared with the online data from the single hydrogen generator 11 for initial screening. When the deviation is significant, a suspected anomaly can be identified, and then the single hydrogen generator 11 can be disassembled for condition assessment, effectively improving detection efficiency.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A condition monitoring system for a converter transformer single-hydrogen unit, characterized in that: Includes a closed hydraulic cylinder (1) with a circular arc bottom, a single hydrogen unit (11), a computer (17), a gas pump (20), and a transformer, wherein: Multiple support legs (15) are provided around the bottom outer side of the closed cylinder (1), a simulated pipeline (2) is provided in the middle of the side wall of the closed cylinder (1), an oil inlet (9) is provided in the lower part of the side wall of the closed cylinder (1), and an oil outlet (6) is provided at the bottom of the closed cylinder (1). An electric heater (3) and an oil thermometer (4) are also installed on the inner wall of the closed oil cylinder (1). The control terminal of the electric heater (3) is connected to the computer (17) through a wire, and the signal output terminal of the oil thermometer (4) is connected to the computer (17) through a wire. A pressure gauge (10) and an airbag (18) are provided on the inner side of the top of the closed oil cylinder (1). The airbag (18) is connected to an air pump (20) located on the outside of the closed oil cylinder (1) through a pipeline. A pressure relief port (19) is also provided on the pipeline. The control terminal of the air pump (20) is connected to a computer (17) through a wire. An oil inlet (7) and an exhaust outlet (8) are also provided at the top of the closed oil cylinder (1); The simulation pipeline (2) is equipped with a single hydrogen device sensor (21), and the simulation pipeline (2) is connected to the single hydrogen device (11) by a metal thread. The signal output end of the single hydrogen device (11) is connected to the background monitoring platform (14) by a wire. A gas relay lead-down port (13) is provided at the bottom of the transformer. The gas relay lead-down port (13) is connected to the gas relay (12) through a pipeline. The single hydrogen device (11) and the gas relay (12) are connected to the riser seat (16) provided at the top of the transformer through a three-way connector. An oil pump (5) is also provided on the outside of the closed oil cylinder (1), and the control terminal of the oil pump (5) is connected to the computer (17) through a wire. One side of the oil pump (5) is connected to the closed oil cylinder (1) near the oil inlet (9) via a pipeline, and the other side of the oil pump (5) is connected to the simulated pipeline (2) via a pipeline. The method for detecting the condition of a single hydrogen converter transformer using the aforementioned condition monitoring system includes the following detection steps: Step 1: Periodically extract oil samples from the top of the transformer through the gas relay lead-down port (13), perform offline chromatographic analysis to obtain the hydrogen content m in the oil, and compare it with the detection result n of the single hydrogen device (11) on the background monitoring platform (14) at the same time. When (mn) / n is greater than 20%, or |mn| is greater than 5ppm, start the status assessment process of the single hydrogen device (11). Step 2: Disconnect the single hydrogen device (11) and connect it to the simulation pipeline (2), open the oil inlet (7) and exhaust port (8) of the oil cylinder, inject the prepared low-concentration standard oil into the closed oil cylinder (1) until oil comes out of the exhaust port (8), and then close the oil inlet (7) and exhaust port (8). Step 3: Control the operation of the electric heater (3) through the computer (17) until the reading of the oil thermometer (4) is consistent with the oil temperature at the top of the transformer. At the same time, control the operation of the oil pump (5) through the computer (17) to inflate the air bag (18) until the reading of the oil pressure gauge (10) is consistent with the oil pressure at the top of the transformer, so as to realize the oil circulation between the simulated pipeline (2) and the closed oil cylinder (1). Step 4: After the value monitored by the single hydrogen device (11) in the background stabilizes at q, an oil sample is drawn from the oil inlet (9), and the hydrogen content p in the oil is obtained by offline chromatography. Then, the pressure relief port (19) is opened. After no gas is discharged from the pressure relief port (19), the pressure relief port (19) is closed. The oil drain port (6) and the exhaust port (8) are opened. After no oil is discharged from the oil drain port (6), the oil drain port (6) and the exhaust port (8) are closed. Step 5: Open the oil inlet (7) and exhaust outlet (8) of the closed oil cylinder (1), inject the prepared high-concentration standard oil into the closed oil cylinder (1) until oil comes out of the exhaust outlet (8), close the oil inlet (7) and exhaust outlet (8), repeat steps 3 and 4, and obtain the detection value u and offline analysis value w of the single hydrogen device (11) under high-concentration standard oil; Step 6: Calculate the evaluation state L of the single hydrogen unit (11) under low concentration standard oil. The calculation formula is as follows: ； The calculation formula for evaluating the state K of the single hydrogen unit (11) under high concentration standard oil is as follows: ； The comprehensive condition assessment coefficient D of the single hydrogen unit (11) is calculated using the following formula: 。 2. The condition monitoring system for a single hydrogen converter unit according to claim 1, characterized in that: The number of the support legs (15) is four, and each support leg (15) is evenly distributed and installed on the bottom outer side of the closed oil cylinder (1).

3. The condition monitoring system for a single hydrogen converter unit according to claim 1, characterized in that: The simulated pipeline (2) is specifically welded to the side wall of the closed oil cylinder (1).

4. The condition monitoring system for a converter transformer single-hydrogen unit according to claim 1, characterized in that: The electric heater (3) is used to control the oil temperature inside the closed oil cylinder (1), and the oil thermometer (4) is used to monitor the oil temperature inside the closed oil cylinder (1).

5. The condition monitoring system for a converter transformer single-hydrogen unit according to claim 1, characterized in that: The airbag (18) is used to control the oil pressure inside the closed cylinder (1), and the oil pressure gauge (10) is used to monitor the oil pressure inside the closed cylinder (1).

6. The condition monitoring system for a converter transformer single-hydrogen unit according to claim 1, characterized in that: The background monitoring platform (14) is used to display the monitoring results of the single hydrogen unit (11).

7. The condition monitoring system for a converter transformer single-hydrogen unit according to claim 1, characterized in that: The single hydrogen device sensor (21) is specifically inserted into the simulated pipeline (2) for detection during the condition assessment.

8. The condition monitoring system for a converter transformer single-hydrogen unit according to claim 1, characterized in that: After the oil pump (5) is connected to the closed oil cylinder (1) and the simulated pipeline (2) through the pipeline, it is used to realize oil circulation and ensure that the standard oil concentration at the oil outlet (9) is consistent with the oil concentration detected by the single hydrogen device (11).

9. The condition monitoring system for a converter transformer single-hydrogen unit according to claim 1, characterized in that: The transformer oil temperature during operation is 60℃-90℃.

Images