Oil Sample Online Monitoring Methods and Systems

Abstract

This invention discloses an online oil sample monitoring method and system that detects the hydrogen concentration in the oil in real time and calculates the rate of change of the hydrogen concentration. If the hydrogen concentration exceeds a set concentration, or the rate of change of the hydrogen concentration exceeds a set threshold, the oil sample is determined to be abnormal. This invention allows for oil sample testing without requiring trains to stop and power to be cut off, thus solving the problems of high technical barriers, long processing times, and high manpower and material costs associated with current traction transformer oil sample analysis methods.

Description

Technical Field

[0001] This invention relates to oil sample testing technology, and in particular to an online oil sample monitoring method and system. Background Technology

[0002] Traction transformers for rail transit vehicles are installed inside the vehicles, typically located under the car, inside the car, or on the roof. They step down the 25kV voltage from the overhead contact line to a suitable voltage to supply power to the train's traction or auxiliary systems, making them one of the core pieces of equipment on rail transit vehicles.

[0003] According to operational maintenance requirements, on-board traction transformers need to undergo periodic oil sampling and testing. The results of these tests help determine the working condition of the transformer's internal components and insulating fluid. Oil sampling requires the train to be stopped and power off. Personnel must open the oil sampling valve on the transformer to collect the sample, which is then sent to a designated testing institution. Both the sampling and testing processes require specialized personnel, increasing the complexity of the operation and presenting challenges such as high technical barriers, high costs, and the inability to obtain test results immediately.

[0004] The oil sampling operation of the vehicle-mounted traction transformer is carried out when the train is stopped and the power is off. The operator opens the oil sampling valve on the transformer and takes out a certain amount of transformer oil using professional oil sampling tools. The transformer oil is stored in a sealed container and sent to the testing agency for testing within a specified time.

[0005] Testing institutions typically use gas chromatography (GC) to detect gases in oil samples. GC is a classic method for analyzing dissolved gases in oil, characterized by high separation efficiency and detection accuracy. An analysis cycle generally includes sampling, degassing, separation, and quantitative analysis. The sampling and delivery process usually takes several hours; if the testing institution is far from the sampling location, the delivery time can be even longer, sometimes several days. After the sample arrives at the testing institution, it needs to undergo degassing, separation, and quantitative analysis. To obtain accurate results, multiple analyses may be required, and the time from analysis to obtaining the final report can take 1 to 2 days. Traditional methods for analyzing traction transformer oil samples are technically demanding, time-consuming, and costly in terms of manpower and resources. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an online oil sample monitoring method and system to address the shortcomings of the existing technology, so as to detect oil samples without the need for trains to stop and power outages, thereby solving the problems of high technical threshold, long time consumption and high manpower and material costs of current traction transformer oil sample analysis methods.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an online oil sample monitoring method, comprising:

[0008] Real-time detection of hydrogen concentration in oil and calculation of the rate of change of hydrogen concentration;

[0009] If the hydrogen concentration exceeds the set concentration, or the rate of change of the hydrogen concentration exceeds the set threshold, the oil sample is determined to be abnormal.

[0010] The hydrogen concentration acquisition process includes:

[0011] The voltage offset data of a single hydrogen sensor under different hydrogen concentrations is obtained. The obtained data is fitted to obtain a curve with the square root of hydrogen concentration on the horizontal axis and the rate of change of hydrogen concentration on the vertical axis. The hydrogen concentration detected by the single hydrogen sensor is calculated using the curve.

[0012] The calculation process for the rate of change of hydrogen concentration includes:

[0013] The difference in hydrogen concentration between adjacent time points is calculated, and the ratio of this difference to the time difference between adjacent time points is the rate of change of hydrogen concentration.

[0014] This invention incorporates an online oil sample monitoring device to monitor the hydrogen content and growth rate in transformer oil, enabling preliminary assessments of potential localized faults within the transformer. If excessively high hydrogen content or a rapid hydrogen growth rate is detected, on-site oil sampling and analysis are then performed, avoiding periodic oil sampling of all transformers. Based on operational experience, the vast majority of transformers are fault-free; therefore, the online monitoring device for traction transformer oil samples reduces the frequency of oil sampling. This allows for oil sample testing without requiring train shutdowns or power outages, thus resolving the issues of high technical barriers, time-consuming processes, and high manpower and material costs associated with current traction transformer oil sample analysis methods.

[0015] When an abnormality is detected in the oil sample, an alarm signal is sent to the train control system.

[0016] As an inventive concept, the present invention also provides an online oil sample monitoring system, comprising:

[0017] A single hydrogen sensor is used to detect the hydrogen concentration in oil samples within an oil pipeline.

[0018] The monitoring unit is used to determine whether the oil sample is abnormal using the above monitoring methods.

[0019] The single hydrogen sensor is electrically connected to the monitoring unit via a junction box, facilitating the monitoring unit's acquisition of data collected by the sensor.

[0020] The single hydrogen sensor is installed on the first section of the oil pipeline of the traction transformer; the first section of the oil pipeline is connected to the second section of the oil pipeline of the single hydrogen sensor through a connecting flange, and the axis of the first section of the oil pipeline is perpendicular to the axis of the second section of the oil pipeline.

[0021] The monitoring system of the present invention also includes:

[0022] Two butterfly valves are installed on the second section of the oil pipeline on both sides of the mounting flange. The butterfly valves have two positions: open and closed, allowing for the connection and disconnection of the oil circuits before and after the valves. When the single hydrogen sensor needs to be disassembled and repaired, both the front and rear butterfly valves are closed, and the oil inside the pipeline is vented via a quick-connect fitting before replacement and repair.

[0023] The single hydrogen sensor includes a detection tube, which contains a detection element, and the detection tube is connected to the housing via a flange.

[0024] To facilitate the installation of the single hydrogen sensor, the flange is provided with multiple mounting holes, the positions of which correspond to the positions of the through holes on the mounting flange.

[0025] Both the outer shell and the flange are made of carbon steel.

[0026] The housing and the flange are welded together as a single unit to improve the working strength of the sensor components.

[0027] A connector is installed on the second section of the oil pipeline between the two butterfly valves. This facilitates draining or replenishing oil in the pipeline.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: by setting an online oil sample monitoring device on the traction transformer, the present invention can detect the oil sample without stopping the train and shutting down the power, thereby solving the problems of high technical threshold, long time consumption and high manpower and material costs of the current traction transformer oil sample analysis method. Attached Figure Description

[0029] Figure 1 This is a flowchart of the single-hydrogen sensor monitoring process according to an embodiment of the present invention;

[0030] Figure 2 This is a structural diagram of the monitoring system according to an embodiment of the present invention;

[0031] Figure 3 This is a structural diagram of a single hydrogen sensor according to an embodiment of the present invention;

[0032] Figure 4 This is a diagram illustrating the installation and sealing structure of a single hydrogen sensor according to an embodiment of the present invention.

[0033] Figure 5 This is a schematic diagram of the single hydrogen sensor circuit interface according to an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In this document, the terms "first," "second," and other similar words are not intended to imply any order, quantity, or importance, but are merely used to distinguish different elements. The terms "one," "a," and other similar words are not intended to indicate the existence of only one of the stated things, but rather that the description refers only to one of the stated things, which may have one or more. The terms "comprising," "including," and other similar words are intended to indicate a logical relationship, not a spatial relationship. For example, "A includes B" means that logically B belongs to A, not that spatially B is located inside A. Furthermore, the meanings of the terms "comprising," "including," and other similar words should be considered open-ended, not closed. For example, "A includes B" means that B belongs to A, but B does not necessarily constitute all of A; A may also include other elements such as C, D, and E.

[0036] Example 1

[0037] This embodiment provides a method for online monitoring of oil samples, such as... Figure 1 As shown, the hydrogen sensor converts changes in hydrogen concentration into voltage signals. A microprocessor module then converts these voltage signals into hydrogen concentration signals and hydrogen concentration change rate signals, which are transmitted to the monitoring system. The monitoring system compares these two signals with preset thresholds. When the hydrogen content or change rate exceeds the set threshold, an alarm signal is sent to the train control system. This system can also store, view, and analyze the detection data.

[0038] Before leaving the factory, the sensor undergoes voltage offset calibration using a standard hydrogen concentration calibration system. For example, when the hydrogen concentration is n1, the corresponding sensor voltage offset is V1. When the hydrogen concentration is manually adjusted to n2, the sensor resistivity changes due to the change in hydrogen concentration, resulting in a voltage offset of V2 at that concentration. This process continues, allowing us to obtain the relationship between different hydrogen concentrations n and the sensor voltage offset V. These data are then processed into a graph with the x-axis representing... A series of scattered points with ordinate (V2-V1) / V1, through curve fitting, yields a x-coordinate of... The vertical axis represents the curve of the fitted function ΔV / V1, which serves as the basis for the sensor to detect hydrogen concentration.

[0039] After obtaining the hydrogen content, the rate of change of hydrogen concentration is obtained according to (n2-n1) / (t2-t1), and the time interval (t2-t1) can be set to 1 hour or other times as needed.

[0040] Example 2

[0041] This embodiment provides an online oil sample monitoring system, such as... Figure 2 As shown. The monitoring system includes: traction transformer oil pipeline 1, front-end butterfly valve 2, rear-end butterfly valve 3, quick connector 4, pipeline mounting flange 5, single hydrogen sensor 6, four-core shielded cable 7, transformer junction box 8, and monitoring display system 9 (i.e., monitoring unit).

[0042] The composition of the single hydrogen sensor 6 is as follows Figure 3 As shown, a detection element (not shown) comprising a palladium alloy thin film is located at the end of the detection tube 601, in direct contact with the transformer oil. An internal circuit board (not shown) is mounted inside the sensor housing 603. The detection element at the end of the detection tube is connected to the internal circuit board via a cable. The detected signal is processed by the circuit board and output through the circuit interface 604. The sensor housing 603 and the sensor flange 602 are made of carbon steel and welded together as a single unit to improve the working strength of the sensor components. The circuit interface 604 is connected to an external four-core shielded cable 7.

[0043] The single hydrogen sensor 6 is installed on the oil line 1 of the traction transformer, avoiding direct installation on the tank wall of the transformer oil tank, so as to reduce the interference of the electromagnetic field inside the transformer on the detection element.

[0044] A pipe mounting flange 5 is welded onto the oil pipeline 1. The upper surface of the pipe mounting flange 5 has an annular rectangular cross-section sealing groove 501, within which an O-ring 502 is placed to seal the internal transformer oil. See details... Figure 4 .

[0045] The pipeline mounting flange 5 also has six through holes evenly distributed in a circle. The positions of these holes are consistent with the positions of the holes on the sensor flange 602, which are used for the installation of fastening bolts. At the same time, a serrated locking washer 503 that matches the fastening bolts is used to achieve good grounding between the sensor housing and the transformer. The sensor housing does not need to be designed with an additional grounding seat or grounding plate.

[0046] A small round hole is also opened at the bottom of the pipeline, and a female quick connector 4 is welded at the position of the small round hole. The female quick connector 4 is equipped with a spring and a sealing structure inside. Under normal circumstances, the oil is sealed by the natural pressure of the spring. When a male quick connector is connected, the internal spring structure can be pushed open to realize the conduction of the oil circuit, so that the oil can be drained or replenished.

[0047] A butterfly valve is installed in both the front and rear pipelines of the single hydrogen sensor 6, namely butterfly valve 2 at the front end and butterfly valve 3 at the rear end. The butterfly valves have two states: open and closed, which realizes the opening and closing of the oil circuits before and after the butterfly valves. When the single hydrogen sensor needs to be disassembled and repaired, butterfly valve 2 at the front end and butterfly valve 3 at the rear end are closed, and the oil inside the oil pipe is emptied through the quick connector before replacement and repair.

[0048] The palladium alloy thin-film sensor is a standard device in the field, and its principle is described as follows: The palladium alloy thin-film sensor inside the detection tube 601 is used to detect the hydrogen concentration in the oil. When the hydrogen in the oil comes into contact with the sensor, the hydrogen is adsorbed onto the surface of the palladium alloy thin film and decomposed into two hydrogen atoms. The hydrogen atoms diffuse through the interior of the palladium alloy thin film, causing a change in its resistivity. The concentration of hydrogen in the oil is obtained by measuring the voltage offset of the palladium alloy thin-film sensor through the internal circuit of the sensor.

[0049] A junction box 8 is installed on the transformer. This junction box 8 can be installed outside the transformer tank by bolting or welding. The junction box has four terminals for connecting a four-core shielded cable. If the testing system malfunctions, the cable can be disconnected at the junction box, and a standard signal can be injected at the disconnection point to determine whether the fault occurs on the sensor side or the monitoring and display system side.

[0050] The signal from the palladium alloy thin-film sensor is processed by a circuit board located inside the sensor housing, and then output to the transformer junction box via a single-hydrogen sensor circuit interface 604 and a four-core shielded cable 7. Circuit interface 604 is as follows: Figure 5 As shown in the table below:

[0051] Table 1

[0052]

[0053] The monitoring and display system 9 is typically located inside the train. It contains data processing and display modules and is connected to the transformer junction box 8 via a four-core shielded cable. The system uses algorithms to calculate the hydrogen content and rate of change in the oil from signals fed back from the sensors. It can also set gas alarm thresholds, which can be set by designers based on past fault experience. When the hydrogen content or rate of change exceeds the set threshold, an alarm signal is sent to the train control system. This system can also store, view, and analyze the detection data.

[0054] According to actual operating requirements, a small oil box can also be installed on the outer wall of the transformer oil tank. The oil in the small oil box can circulate with the oil in the main oil tank. An installation and sealing interface is designed on the small oil box, and a single hydrogen sensor is installed on the small oil box.

[0055] The installation method of a single hydrogen sensor is not limited to bolting the flange; the interface of the single hydrogen sensor can also be designed as a threaded seal.

[0056] Depending on the actual on-site operation needs, if the detection system is close to the sensor components, a transformer junction box may not be required, and the four-core shielded cable can be directly connected to the monitoring system after exiting the single hydrogen sensor.

[0057] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for online monitoring of oil samples, characterized in that, include: Real-time detection of hydrogen concentration in oil and calculation of the rate of change of hydrogen concentration; If the hydrogen concentration exceeds the set concentration, or the rate of change of the hydrogen concentration exceeds the set threshold, the oil sample is determined to be abnormal. The hydrogen concentration acquisition process includes: The voltage offset data of a single hydrogen sensor under different hydrogen concentrations is obtained. The obtained data is fitted to obtain a curve with the square root of hydrogen concentration on the horizontal axis and the rate of change of hydrogen concentration on the vertical axis. The hydrogen concentration detected by the single hydrogen sensor is calculated using the curve. The calculation process for the rate of change of hydrogen concentration includes: The difference in hydrogen concentration between adjacent time points is calculated, and the ratio of this difference to the time difference between adjacent time points is the rate of change of hydrogen concentration.

2. The online oil sample monitoring method according to claim 1, characterized in that, When an abnormality is detected in the oil sample, an alarm signal is sent to the train control system.

3. An online oil sample monitoring system, characterized in that, include: A single hydrogen sensor is used to detect the hydrogen concentration in oil samples within an oil pipeline. A monitoring unit is used to determine whether an oil sample is abnormal using the monitoring method described in claim 1 or 2.

4. The online oil sample monitoring system according to claim 3, characterized in that, The single hydrogen sensor is electrically connected to the monitoring unit via a junction box.

5. The online oil sample monitoring system according to claim 3, characterized in that, The single hydrogen sensor is installed on the first section of the oil pipeline of the traction transformer; the first section of the oil pipeline is connected to the second section of the oil pipeline of the single hydrogen sensor through a connecting flange, and the axis of the first section of the oil pipeline is perpendicular to the axis of the second section of the oil pipeline.

6. The online oil sample monitoring system according to claim 5, characterized in that, Also includes: Two butterfly valves are installed on the second section of the oil pipeline on both sides of the mounting flange.

7. The online oil sample monitoring system according to claim 5, characterized in that, The single hydrogen sensor includes a detection tube, which contains a detection element. The detection tube is connected to the housing via a flange. Preferably, the flange has multiple mounting holes, the positions of which correspond to the positions of the through holes on the mounting flange.

8. The online oil sample monitoring system according to claim 7, characterized in that, Both the outer shell and the flange are made of carbon steel.

9. The online oil sample monitoring system according to claim 7 or 8, characterized in that, The outer shell and the flange are welded together as a whole.

10. The online oil sample monitoring system according to claim 3, characterized in that, A joint is installed on the second section of the oil pipeline between the two butterfly valves.

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