An oil chromatography online monitoring system

Abstract

The application discloses an oil chromatography online monitoring system and a self-produced carrier gas control method thereof, and belongs to the technical field of power equipment insulation monitoring. The system comprises an oil sample collection module, an oil-gas separation module, a gas collection module, a detection module, a data processing module and a self-produced carrier gas source module. The self-produced carrier gas source module comprises, sequentially connected along the airflow direction, an air purification unit, a gas storage unit, a pressure regulating unit and a control unit. The air purification unit is sequentially provided with a filter, a color-changing silica gel chamber and an activated carbon chamber along the airflow direction, and a buffer heat dissipation cavity with heat dissipation fins is arranged between the color-changing silica gel chamber and the activated carbon chamber. Through sequential optimization of the purification unit, self-adaptive bypass control of temperature and humidity, predictive gas supply and detection window supply guaranteeing collaborative control, the problems of pressure ripple, temperature difference drift and gas supply interruption in the existing self-produced carrier gas scheme are solved, and the application is particularly suitable for online monitoring of dissolved gases in the main transformer oil in remote scenes such as wind power plants.

Description

Technical Field

[0001] This invention relates to the field of insulation monitoring technology for power equipment, specifically to an online oil chromatography monitoring system for online monitoring of dissolved gases in transformer oil, and particularly to the structural improvement and control method of the self-generated carrier gas source module in the system. Background Technology

[0002] An online oil chromatography monitoring system is a precision device integrating control, measurement, and analysis technologies. It monitors and analyzes the characteristic gas components of insulating oil to keep track of the main transformer's operating status. Traditional online oil chromatography monitoring devices use high-pressure carrier gas cylinders (such as high-purity nitrogen or high-purity air cylinders) as the gas source, utilizing the high-pressure gas in the cylinders to carry the sample gas into the chromatographic column for separation and detection.

[0003] However, in actual operation, the traditional device has the following shortcomings: (1) As the service time of the carrier gas cylinder is extended, the pressure inside the cylinder gradually decreases. When the pressure is lower than the minimum working pressure required for chromatographic detection, the device is forced to shut down; (2) Replacing the carrier gas cylinder requires professional chromatographic technicians to be on-site, resulting in additional material and labor costs; (3) The high-pressure cylinder is placed near the transformer, which poses certain safety risks; (4) For wind farms in remote areas, the operation and maintenance cycle is long. After the carrier gas is exhausted, the device is shut down for a long time, resulting in the lack of monitoring of the main transformer status.

[0004] To address the aforementioned issues, solutions have emerged in recent years that utilize self-generated carrier gas modules to replace gas cylinders. For example, CN103149279A discloses a carrier gas-free online oil chromatography monitoring device, which achieves self-generation and self-use of carrier gas by adding a gas generation module inside the monitoring equipment. CN204086229U discloses a dedicated air generator for online monitoring of transformer oil chromatography, which uses an air compressor in conjunction with a multi-stage purification system to generate clean air as carrier gas. CN224005032U discloses a carrier gas self-generation device for wind farms, which uses an air generator in conjunction with a gas storage tank and a control unit to achieve a continuous supply of carrier gas.

[0005] However, existing self-generated carrier gas solutions mainly address the single issue of "replacing gas cylinders with self-generated gas," lacking effective solutions for the secondary problems introduced by self-generated carrier gas. Specifically, these problems manifest as follows: (1) the start-up and shutdown of the air compressor cause carrier gas pressure ripple, affecting the stability of chromatographic detection; (2) the efficiency of the purification unit drifts under outdoor temperature differences, with activated carbon potentially desorbing at high temperatures and the adsorption capacity of discoloring silica gel decreasing at low temperatures; (3) the start-up and shutdown of the air compressor do not match the chromatographic detection cycle, which may lead to interruption of gas supply or insufficient pressure within the detection window. According to statistics, in actual wind farm applications, the downtime rate caused by the above problems is as high as 15% to 20%, seriously affecting the continuity of main transformer status monitoring. Summary of the Invention

[0006] The technical problem to be solved by this invention is: to address the issues in existing self-generated carrier gas type online oil chromatography monitoring systems, such as pressure ripple introduced by the self-generated carrier gas affecting the stability of chromatographic detection, outdoor temperature difference causing efficiency drift of the purification unit, and the risk of gas supply interruption due to mismatch between air compressor start-up and shutdown and chromatographic detection cycle. This invention provides an online oil chromatography monitoring system that can provide stable gas supply, adapt to outdoor temperature difference environments, and work in coordination with the detection cycle.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] An online oil chromatography monitoring system includes an oil sample acquisition module, an oil-gas separation module, a gas acquisition module, a detection module, a data processing module, and a self-generated carrier gas source module.

[0009] The self-generated carrier gas source module includes an air purification unit, a gas storage unit, a pressure regulating unit, and a control unit connected sequentially along the airflow direction.

[0010] The air purification unit is provided with a filter, a color-changing silica gel chamber, and an activated carbon chamber in sequence along the airflow direction. A buffer heat dissipation cavity is provided between the color-changing silica gel chamber and the activated carbon chamber, and heat dissipation fins are arranged inside the buffer heat dissipation cavity.

[0011] The control unit is electrically connected to the air purification unit, the gas storage unit, and the pressure regulating unit, and is configured to provide a constant pressure carrier gas to the detection module in real time through program control.

[0012] Furthermore, the self-generated carrier gas source module is also equipped with a temperature control device, which includes a first temperature sensor and a second temperature sensor respectively installed in the activated carbon chamber and the color-changing silica gel chamber, as well as corresponding heating belts. A humidity sensor is also installed downstream of the color-changing silica gel chamber, and the humidity sensor is connected to the control unit. The air purification unit is also equipped with a bypass flow path: the filter outlet is split, one path is the main path through the color-changing silica gel chamber and the activated carbon chamber, and the other path is a bypass path that bypasses the activated carbon chamber. The bypass path and the main path merge before the flow stabilizing valve; an electrically controlled switching valve is installed on the bypass path, and the electrically controlled switching valve is connected to the control unit. The control unit is also configured to: (a) activate the heating belt corresponding to the color-changing silica gel chamber when the value detected by the first temperature sensor is lower than the first set temperature; (b) control the electrically controlled switching valve to switch to the bypass flow path when the value detected by the second temperature sensor is higher than the second set temperature, so that the airflow bypasses the activated carbon chamber; (c) control the electrically controlled switching valve to switch to the bypass flow path when the value detected by the humidity sensor is higher than the third set humidity, and report a color-changing silica gel saturation alarm.

[0013] Furthermore, the gas storage unit is equipped with a pressure sensor, and a flow meter is located downstream of the pressure regulating unit. Both the pressure sensor and the flow meter are connected to the control unit. The control unit is also configured to: obtain the next detection window time t_next and the gas consumption Q_last of the previous detection cycle from the detection module; calculate the expected gas consumption Q_exp; back-calculate the minimum tank pressure P_need required before the detection window based on Q_exp and the volume of the gas storage unit; and dynamically adjust the compressor's starting pressure threshold to ensure that the gas storage unit pressure is not lower than P_need before the next detection window.

[0014] Furthermore, the compressor of the self-generated carrier gas source module is a low-noise variable frequency compressor, and the frequency converter is connected to the control unit; the control unit adjusts the charging rate by adjusting the output frequency of the frequency converter, so that the compressor runs at a speed matching Q_exp.

[0015] Furthermore, the pressure regulating unit is equipped with a two-stage pressure stabilization structure, which includes a first-stage pressure stabilizing valve and a second-stage pressure stabilizing valve connected in series, and an electrically controlled bypass valve connected in parallel across the second-stage pressure stabilizing valve. The control unit is also configured to: when the time remaining until the next detection window is less than a preset time Δt and the current pressure of the gas storage unit is lower than P_need, open the electrically controlled bypass valve, allowing the carrier gas to be directly supplied to the detection module from the first-stage pressure stabilizing valve, bypassing the second-stage pressure stabilizing valve.

[0016] Furthermore, the electrically controlled bypass valve is a proportional regulating valve, and the control unit is also configured to linearly adjust the opening of the electrically controlled bypass valve according to the difference between the current pressure of the gas storage unit and P_need, so that the carrier gas flow rate transitions smoothly.

[0017] Furthermore, a one-way valve is provided at the junction of the bypass and the main line, with the one-way valve pointing towards the inlet of the flow stabilizing valve to prevent the main line airflow from flowing back into the bypass.

[0018] Furthermore, the activated carbon chamber is a drawer-type quick-change module. The cabinet is equipped with a guide rail that cooperates with the activated carbon chamber slider. After the activated carbon chamber is in place, it is locked by a buckle. The cabinet is also equipped with a limit switch corresponding to the activated carbon chamber. The limit switch is connected to the control unit. When the limit switch is not triggered, the control unit determines that the activated carbon chamber is not installed in place and cuts off the carrier gas output.

[0019] Furthermore, the activated carbon chamber is provided with a transparent observation window, and a color indicator layer is provided on the inside of the observation window for visually judging the saturation level of the activated carbon; or, the control unit is also provided with a timing module to record the cumulative usage time of the activated carbon chamber, and issue a replacement prompt when the cumulative usage time exceeds the preset lifespan.

[0020] Furthermore, the gas storage unit includes a buffer tank and a main gas storage tank. The air inlet of the buffer tank is connected to the compressor outlet via a purification unit, and the air outlet of the buffer tank is connected to the air inlet of the main gas storage tank via a first electrically controlled valve. The air outlet of the main gas storage tank is connected to a pressure regulating unit. A pressure sensor is installed in both the buffer tank and the main gas storage tank. The control unit controls the filling and discharging of the buffer tank with a first pressure threshold range and controls the gas supply pressure of the main gas storage tank with a second pressure threshold range, wherein the lower limit of the second pressure threshold range is higher than the lower limit of the first pressure threshold range.

[0021] Furthermore, the detection module is a gas chromatograph detector, and the carrier gas output by the self-generated carrier gas source module is purified air or nitrogen; the oil chromatography online monitoring system is used for monitoring dissolved gases in the main transformer oil of wind power plants.

[0022] Beneficial effects

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Optimized purification unit sequence: The purification unit sequence was adjusted to filter → color-changing silica gel chamber → activated carbon chamber, with a buffer heat dissipation cavity set between the two. This avoids the problem of water vapor in the hot and humid air at the air compressor outlet competing for the adsorption sites of activated carbon, and at the same time eliminates the baking effect of the exothermic adsorption of color-changing silica gel on activated carbon. This significantly improves the adsorption efficiency of activated carbon for hydrocarbon gases, reduces the background concentration of hydrocarbons such as CH4 in the carrier gas, and improves the accuracy of oil chromatography detection.

[0025] 2. Temperature and Humidity Adaptive Purification: By installing temperature sensors in the activated carbon chamber and the color-changing silica gel chamber respectively, and a humidity sensor downstream of the color-changing silica gel chamber, along with a bypass flow path and an electronically controlled switching valve, the purification unit achieves adaptive adjustment under different ambient temperatures. At low temperatures, the silica gel is heated to maintain adsorption activity; at high temperatures, the bypass bypasses the activated carbon to avoid desorption and back pollution; and at high humidity, the bypass is activated and an alarm is triggered to prompt the replacement of the silica gel, ensuring that the purification unit maintains stable purification efficiency under outdoor temperature differences.

[0026] 3. Predictive gas supply: By acquiring the chromatographic detection cycle and historical gas consumption, the start and stop thresholds of the compressor are dynamically adjusted to ensure that the gas storage unit maintains sufficient pressure reserves before each detection window. This avoids the problem of insufficient gas supply during peak detection periods in traditional fixed threshold schemes, and also reduces the number of invalid start and stop cycles of the air compressor, thus extending the compressor's lifespan.

[0027] 4. Coordinated Supply of Carrier Gas within the Detection Window: When the detection window is approaching and the gas storage pressure is insufficient, the second-stage fine stabilizer is bypassed via an electronically controlled bypass valve, and the first-stage coarse stabilizer directly supplies the carrier gas, ensuring a continuous supply within the detection window and preventing column flow rate instability due to excessive pressure drop. The application of a proportional control valve further achieves a smooth flow transition.

[0028] 5. Enhanced Ease of Maintenance and Safety: The activated carbon chamber utilizes a drawer-type quick-change module with a limit switch, allowing maintenance personnel to replace the activated carbon without tools. Furthermore, the system automatically cuts off the carrier gas output if the activated carbon is not installed correctly, eliminating safety hazards caused by human error. The dual-tank structure further isolates the gas supply pressure from compressor start-up and shutdown, making it suitable for high-frequency testing scenarios.

[0029] The above-mentioned technical measures work together to solve the core problem of the stability of self-generated carrier gas supply under outdoor temperature difference conditions, forming a complete solution from gas source purification and pressure regulation to detection cycle matching. Attached Figure Description

[0030] Figure 1 This is a block diagram illustrating the overall principle and structure of the online oil chromatography monitoring system of the present invention.

[0031] Figure 2 This is a schematic diagram of the structure of the self-generated carrier gas source module of the present invention.

[0032] Figure 3 This is the overall block diagram of the system integration control logic of the present invention.

[0033] Figure 4 This is the control logic block diagram for the control unit. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0035] Example 1

[0036] This embodiment provides an online oil chromatography monitoring system, which includes an oil sample acquisition module, an oil-gas separation module, a gas acquisition module, a detection module, a data processing module, and a self-generated carrier gas source module.

[0037] The oil sampling module is used to collect insulating oil samples from the main transformer tank. It includes an electric oil pump (model: German KNF N86KTE), a solenoid valve (model: SMC VXZ series) and oil pipelines. The oil circulation is controlled by the control unit to remove stagnant oil in the connecting pipelines before quantitative sampling.

[0038] The oil-gas separation module is used to quickly separate the dissolved gases from the oil sample. It adopts vacuum degassing or headspace degassing. In this embodiment, vacuum degassing is used. The degassing chamber volume is 20 mL, the degassing time is 15 minutes, and the degassing temperature is controlled at 65±1℃.

[0039] The gas acquisition module includes a connector, which typically uses a six-way valve (model: Valco C6W series) and a quantitative tube (1 mL volume). Under the propulsion of the carrier gas, the sample gas passes through the chromatographic column for separation and sequentially enters the gas detector, which is used to quantitatively send the separated gas into the chromatographic detection module.

[0040] Traditionally, the detection module consists of a gas chromatographic detector composed of a chromatographic column and a sensor. In this embodiment, a micro gas chromatograph (model: Agilent 490 Micro GC) is used, equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID), which can simultaneously detect seven characteristic gases: H2, CH4, C2H4, C2H6, C2H2, CO, and CO2.

[0041] The data processing module includes a data acquisition card (model: NI USB-6210) and an embedded processing unit (model: TIAM3358 Cortex-A8 processor), which stores, calculates and analyzes the detected chromatographic data, and uploads the data to a remote data processing server via an RS485 interface.

[0042] Reference Figure 2 The self-generated carrier gas source module is the air generator, which generally includes an air purification unit 100, an air storage unit 200, a pressure regulating unit 300, and a control unit 400 connected in sequence along the airflow direction.

[0043] The air purification unit 100 is equipped with a filter 110, a color-changing silica gel chamber 120, and an activated carbon chamber 130 sequentially along the airflow direction. The filter 110 uses a polypropylene melt-blown filter element (model: Parker 05SS001, filtration accuracy 5μm) to remove dust particles and other impurities from the air. The color-changing silica gel chamber 120 is filled with blue color-changing silica gel (particle size 3-5mm, filling amount 500g) to absorb moisture from the air. The silica gel changes from blue to pink after absorbing moisture, which can be visually determined through a transparent observation window. The activated carbon chamber 130 is filled with coconut shell activated carbon (particle size 4-8 mesh, iodine value ≥1000mg / g, filling amount 300g) to absorb hydrocarbon organic compounds (mainly CH4, C2H6, etc.) from the air.

[0044] It is worth noting that in this embodiment, the color-changing silica gel chamber 120 is placed upstream of the activated carbon chamber 130, which is the reverse of the conventional air generator sequence of "filter → activated carbon → silica gel". This is because the air outlet of the air compressor is in a humid and hot state (relative humidity can reach over 80%). If it passes through the activated carbon first, water vapor will preferentially occupy the micropore sites of the activated carbon, resulting in a significant decrease in the activated carbon's adsorption capacity for hydrocarbon gases. Placing the color-changing silica gel chamber upstream to remove water first can protect the adsorption performance of the downstream activated carbon. At the same time, the adsorption of water by the color-changing silica gel is an exothermic reaction, and the temperature at the center of the silica gel bed can reach 60°C. To prevent this heat from being directly transferred to the downstream activated carbon chamber and causing the activated carbon to heat up and desorb, a buffer heat dissipation cavity 140 is set between the color-changing silica gel chamber 120 and the activated carbon chamber 130. The buffer heat dissipation cavity 140 is equipped with aluminum heat dissipation fins (fin spacing 5mm, height 20mm), which can dissipate the heat released by the silica gel through natural convection, ensuring that the temperature entering the activated carbon chamber does not exceed 35°C.

[0045] The temperature control device includes a first temperature sensor (PT100 platinum resistance thermometer, installed inside the color-changing silica gel chamber 120), a second temperature sensor (PT100 platinum resistance thermometer, installed inside the activated carbon chamber 130), and corresponding first and second heating belts (silicone rubber heating belts, 50W power, wrapped around the outer walls of the color-changing silica gel chamber and the activated carbon chamber). When the value detected by the first temperature sensor is below 15℃ (low temperature condition in winter), the control unit activates the first heating belt of the color-changing silica gel chamber to maintain the silica gel chamber temperature in the optimal adsorption temperature range of 20-25℃. When the value detected by the second temperature sensor is above 40℃ (high temperature condition in summer), the control unit determines that there is a risk of desorption and back-contamination of the activated carbon and activates the bypass protection mechanism.

[0046] Downstream of the color-changing silica gel chamber 120, there is also a humidity sensor (model: Swiss Sensirion SHT35, accuracy ±1.5%RH) for real-time monitoring of the relative humidity of the air after water removal. When the humidity sensor 170 detects a value higher than 60%RH, it indicates that the color-changing silica gel is close to saturation, and the control unit issues a replacement prompt.

[0047] The air purification unit 100 also includes a bypass flow path 180. The bypass flow path 180 splits the outlet of the filter 110, with one path leading to the main path through the color-changing silica gel chamber 120 and the activated carbon chamber 130, and the other path bypassing the activated carbon chamber 130. Both paths merge with the main path at the one-way valve 190 before entering the air storage unit 200. The bypass path is equipped with an electrically controlled switching valve 181 (model: SMC VXZ2120-03-5DZ1, two-position two-way solenoid valve), which is connected to the control unit 400. When the second temperature sensor detects a value higher than 40℃ or the humidity sensor detects a value higher than 60%RH, the control unit 400 controls the electrically controlled switching valve 181 to switch to the bypass flow path, allowing the airflow to bypass the activated carbon chamber 130, preventing high-temperature desorption contamination or moisture from entering the activated carbon chamber after silica gel saturation. A one-way valve 190 (model: SMC AKB series, opening pressure 0.02MPa) is installed at the junction of the bypass and the main line to prevent the main line airflow from flowing back into the bypass.

[0048] The gas storage unit 200 includes a stainless steel gas storage tank (10L capacity, design pressure 1.0MPa), and a pressure sensor 210 (model: German FirstSensor HCEM series, range 0-1.6MPa, accuracy 0.5%FS) is installed on the top of the gas storage tank to monitor the gas pressure inside the tank in real time.

[0049] The pressure regulating unit 300 includes a flow regulating valve 310 (model: Brooks SLA5850, mass flow controller, range 0-500mL / min), a first-stage pressure regulating valve 321 (model: SMC AR20-02BG, set pressure 0.4MPa), a second-stage pressure regulating valve 322 (model: SMC AR10-01BG, set pressure 0.15MPa), and an electrically controlled bypass valve 330 (model: SMC VXZ2120-03-5DZ1) connected in parallel across the second-stage pressure regulating valve 322. The electrically controlled bypass valve 330 is normally closed, and the carrier gas is output to the detection module after being regulated by both the first-stage pressure regulating valve 321 and the second-stage pressure regulating valve 322. When the detection window is approaching and the gas storage pressure is insufficient, the control unit opens the electrically controlled bypass valve 330, allowing direct supply from the first-stage pressure regulating valve 321, bypassing the second-stage pressure regulating valve 322 to reduce pressure loss.

[0050] The compressor 500, which is a self-produced carrier air source module, is a low-noise variable frequency oil-free air compressor (model: German Jun-AirOF302-25M, displacement 25L / min, maximum pressure 0.8MPa, noise ≤45dB(A)). The inverter 510 (model: Delta VFD-M series) is connected to the control unit 400, and the compressor speed is controlled by adjusting the inverter output frequency (20-60Hz).

[0051] The control unit 400 uses an industrial-grade ARM controller (model: STM32F407VG, Cortex-M4 core, 168MHz clock speed), with built-in 256KB Flash and 192KB SRAM. The control unit 400 is electrically connected to the compressor inverter 510, the electrically controlled bypass valve 330, the electrically controlled switching valve 181, the first temperature sensor, the second temperature sensor, the humidity sensor, the pressure sensors (211, 212), the flow meter, the limit switch, and the main control board of the detection module.

[0052] Reference Figure 4 The control unit 400 is configured to execute the following control logic:

[0053] Step S1: Obtain the next detection window time t_next from the detection module (in this embodiment, the detection cycle is 1 hour by default, i.e., t_next = current time + 3600 seconds), and the gas consumption Q_last of the previous detection cycle (accumulated by the flow meter in the flow stabilizing valve 310).

[0054] Step S2: Calculate the expected gas consumption Q_exp = k × Q_last, where k is the load correction coefficient, and in this embodiment, k = 1.2. For wind power scenarios, the value of k can be adaptively adjusted according to the main transformer load curve—k is 1.3-1.5 during peak load periods (high wind speed, high output) and 1.0-1.1 during off-peak periods.

[0055] Step S3: Based on Q_exp and the gas tank volume V_tank (10L), calculate the minimum tank pressure required before the detection window: P_need = (Q_exp × P_atm) / V_tank + P_margin, where P_atm is standard atmospheric pressure (0.101325MPa) and P_margin is the safety margin (0.05MPa in this embodiment). For example, if Q_exp = 2L (under standard conditions), then P_need ≈ (2×0.101325) / 10 + 0.05 = 0.0703MPa.

[0056] Step S4: Dynamically adjust the starting pressure threshold of compressor 500. The default starting pressure threshold is 0.3MPa, and the stopping pressure threshold is 0.6MPa. When P_need > the current pressure P_current, lower the starting pressure threshold to P_need + 0.05MPa to precharge the compressor; when P_need ≤ P_current, maintain the original threshold or adjust it appropriately to reduce the start-stop frequency.

[0057] Step S5: Adjust the compressor speed according to Q_exp. The target speed n_target = (Q_exp / T_remain) × K, where T_remain = t_next - the current time, and K is the compressor characteristic coefficient (K = 1500 rpm·min / L in this embodiment). The control unit adjusts the compressor speed to n_target through the inverter 510, so that the compressor operates at a speed that matches the expected gas consumption, rather than starting and stopping at full speed.

[0058] Step S6: When the time remaining until the next detection window is less than a preset time Δt (10 minutes in this embodiment) and the current pressure P_current of the gas storage unit is lower than P_need, the electrically controlled bypass valve 330 is opened, and the carrier gas is directly supplied to the detection module by the first-stage pressure regulating valve 321, skipping the second-stage pressure regulating valve 322. The electrically controlled bypass valve 330 is a proportional regulating valve. The control unit linearly adjusts the opening degree of the electrically controlled bypass valve 330 (0-100%) according to the difference between (P_need - P_current), so that the carrier gas flow rate transitions smoothly and avoids pressure sudden changes affecting the column balance.

[0059] Step S7: After the detection window ends, close the electronically controlled bypass valve 330 and restore the operation of the second-stage pressure regulating valve 322.

[0060] The activated carbon chamber 130 adopts a drawer-type quick-change module. The cabinet is equipped with guide rails that cooperate with the activated carbon chamber slider. After the activated carbon chamber is in place, it is locked by a spring clip. The cabinet is also equipped with a limit switch (model: Omron D2F-01L) corresponding to the activated carbon chamber. The limit switch is connected to the control unit 400. When the limit switch is not triggered, the control unit 400 determines that the activated carbon chamber is not installed in place and cuts off the carrier gas output, while issuing an audible and visual alarm.

[0061] The activated carbon chamber 130 is equipped with a transparent observation window, and the inside of the observation window has a color indicator layer (coated with CoCl2 test paper, which turns red when wet) for visually determining whether the activated carbon is saturated with moisture. The control unit 400 is also equipped with a timing module (based on the RTC clock DS3231) to record the cumulative usage time of the activated carbon chamber. When the cumulative usage time exceeds the preset lifespan (6 months in this embodiment), a replacement prompt is issued via touch screen or remote communication.

[0062] Example 2

[0063] This embodiment is basically the same as Embodiment 1, except that the carrier gas output by the self-generated carrier gas source module is nitrogen, not air. Correspondingly, the activated carbon chamber 130 in the air purification unit 100 is replaced with a molecular sieve chamber (filled with 13X molecular sieves to remove trace impurities from the nitrogen), while the color-changing silica gel chamber 120 remains unchanged. The compressor 500 is replaced with a nitrogen generator (model: Peak Scientific Genius 1022, using the PSA pressure swing adsorption principle, with a gas production rate of 22L / min and a nitrogen purity of 99.5%). The remaining structure and control logic are the same as in Embodiment 1.

[0064] This embodiment is suitable for situations where higher purity of carrier gas is required, or for scenarios where customers are accustomed to using nitrogen as the chromatographic carrier gas.

[0065] Example 3

[0066] This embodiment is basically the same as Embodiment 1, except that the oil chromatography online monitoring system is applied to an inland substation (non-wind power scenario) with an ambient temperature range of -10℃ to +45℃ and relatively low humidity. Therefore, the first set temperature of the temperature control device is adjusted to 10℃, and the second set temperature is adjusted to 45℃; the third set humidity of the humidity sensor is adjusted to 70%RH. The remaining structure and control logic are the same as in Embodiment 1.

[0067] Example 4

[0068] This embodiment is basically the same as Embodiment 1, except that: (Refer to...) Figure 2 The gas storage unit 200 adopts a dual-tank structure—including a buffer tank 201 (3L volume) and a main gas storage tank 202 (10L volume). The air inlet of the buffer tank 201 is connected to the air compressor outlet via a purification unit, and the air outlet of the buffer tank 201 is connected to the air inlet of the main gas storage tank 202 via a first solenoid valve 203. The air outlet of the main gas storage tank 202 is connected to a pressure regulating unit 300. A pressure sensor (211, 212) is installed in both the buffer tank 201 and the main gas storage tank 202. The control unit 400 controls the charging and discharging of the buffer tank 201 within a first pressure threshold range (0.6-0.8 MPa) and controls the gas supply pressure of the main gas tank 202 within a second pressure threshold range (0.4-0.6 MPa). The lower limit of the second pressure threshold range (0.4 MPa) is higher than the lower limit of the first pressure threshold range (0.6 MPa). Note the logic here: normally, the buffer tank pressure should be higher than the main gas tank pressure to replenish the main gas tank. In this embodiment, the first pressure threshold range is 0.6-0.8 MPa, and the second pressure threshold range is 0.4-0.6 MPa, conforming to the pressure gradient. The dual-tank structure further isolates the pressure disturbance of the main gas tank caused by the compressor's start-up and shutdown, making it suitable for scenarios with high detection frequency (such as a detection cycle shortened to 30 minutes / time).

[0069] Summary of parameter range

[0070] The specific values ​​in the above embodiments (such as a gas storage tank volume of 10L, a pressure threshold of 0.3-0.6MPa, a preset duration Δt = 10 minutes, a set temperature of 15℃ / 40℃, and a set humidity of 60%RH) are all exemplary values. In actual applications, these values ​​can be adjusted according to system scale, environmental conditions, and testing requirements. For example, the gas storage unit volume can be selected from 5-20L, the pressure threshold can be adjusted within the range of 0.2-0.8MPa, the preset duration Δt can be selected within the range of 5-30 minutes, the first set temperature can be selected within the range of 5-20℃, the second set temperature can be selected within the range of 35-50℃, and the third set humidity can be selected within the range of 50-80%RH. These parameter adjustments all fall within the protection scope of this invention.

[0071] The oil chromatography online monitoring system provided by this invention solves the technical problems such as pressure ripple, temperature drift, and gas supply interruption in traditional cylinder-based carrier gas solutions and existing self-generated carrier gas solutions through structural innovation and control logic optimization of the self-generated carrier gas source module. It can be widely used in online monitoring of dissolved gases in main transformer oil in wind farms, photovoltaic power plants, conventional substations and other places, and has good industrial applicability.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An online oil chromatography monitoring system, characterized in that, It includes an oil sample collection module, an oil-gas separation module, a gas collection module, a detection module, a data processing module, and a self-generated carrier gas source module; The self-generated carrier gas source module includes an air purification unit, a gas storage unit, a pressure regulating unit, and a control unit connected sequentially along the airflow direction; The air purification unit is provided with a filter, a color-changing silica gel chamber, and an activated carbon chamber in sequence along the airflow direction, and a buffer heat dissipation cavity is provided between the color-changing silica gel chamber and the activated carbon chamber, and heat dissipation fins are arranged in the buffer heat dissipation cavity. The control unit is electrically connected to the air purification unit, the gas storage unit, and the pressure regulating unit, and is configured to provide a constant pressure carrier gas to the detection module in real time through program control.

2. The online oil chromatography monitoring system according to claim 1, characterized in that, The self-generated carrier gas source module is also equipped with a temperature control device, which includes a first temperature sensor and a second temperature sensor respectively arranged in the activated carbon chamber and the color-changing silica gel chamber, as well as a corresponding heating belt. A humidity sensor is also provided downstream of the color-changing silicone chamber, and the humidity sensor is connected to the control unit. The air purification unit is also equipped with a bypass flow path: the filter outlet is split, one path is the main path that passes through the color-changing silica gel chamber and the activated carbon chamber, and the other path is a bypass path that bypasses the activated carbon chamber. The bypass path and the main path merge in front of the flow stabilizing valve; the bypass path is equipped with an electronically controlled switching valve, which is connected to the control unit. The control unit is also configured to: (a) When the value detected by the first temperature sensor is lower than the first set temperature, the heating belt corresponding to the color-changing silicone chamber is activated; (b) When the value detected by the second temperature sensor is higher than the second set temperature, the electronically controlled switching valve is switched to the bypass flow path so that the airflow bypasses the activated carbon chamber; (c) When the humidity sensor detects a value higher than the third set humidity, the control electronic switching valve switches to the bypass flow path and reports a color-changing silica gel saturation alarm.

3. The online oil chromatography monitoring system according to claim 1 or 2, characterized in that, The gas storage unit is equipped with a pressure sensor, and a flow meter is located downstream of the pressure regulating unit. Both the pressure sensor and the flow meter are connected to the control unit. The control unit is also configured to: obtain the next detection window time t_next and the gas consumption Q_last of the previous detection cycle from the detection module, calculate the expected gas consumption Q_exp, back-calculate the minimum tank pressure P_need required before the detection window based on Q_exp and the volume of the gas storage unit, and dynamically adjust the starting pressure threshold of the compressor so that the pressure of the gas storage unit is not lower than P_need before the next detection window.

4. The online oil chromatography monitoring system according to claim 3, characterized in that, The compressor of the self-generated carrier gas source module is a low-noise variable frequency compressor, and the frequency converter is connected to the control unit. The control unit adjusts the charging rate by adjusting the output frequency of the frequency converter, so that the compressor runs at a speed matching Q_exp.

5. The online oil chromatography monitoring system according to claim 4, characterized in that, The pressure regulating unit is provided with a two-stage pressure regulating structure, which includes a first-stage pressure regulating valve and a second-stage pressure regulating valve connected in series, and an electrically controlled bypass valve connected in parallel across the two ends of the second-stage pressure regulating valve. The control unit is also configured to: when the time to the next detection window is less than a preset time Δt and the current pressure of the gas storage unit is lower than P_need, open the electronically controlled bypass valve, and supply carrier gas directly to the detection module from the first-stage pressure regulating valve, skipping the second-stage pressure regulating valve.

6. The online oil chromatography monitoring system according to claim 5, characterized in that, The electrically controlled bypass valve is a proportional regulating valve, and the control unit is also configured to linearly adjust the opening of the electrically controlled bypass valve according to the difference between the current pressure of the gas storage unit and P_need, so that the carrier gas flow rate transitions smoothly.

7. The online oil chromatography monitoring system according to claim 2, characterized in that, A one-way valve is provided at the junction of the bypass and the main line. The one-way valve is directed towards the inlet of the flow stabilizing valve to prevent the main line airflow from flowing back into the bypass.

8. The online oil chromatography monitoring system according to claim 1, characterized in that, The activated carbon chamber is equipped with a transparent observation window, and a color indicator layer is provided on the inside of the observation window for visually judging the saturation level of the activated carbon; or, the control unit is also equipped with a timing module to record the cumulative usage time of the activated carbon chamber, and issue a replacement prompt when the cumulative usage time exceeds the preset lifespan.

9. The online oil chromatography monitoring system according to claim 1, characterized in that, The gas storage unit includes a buffer tank and a main gas storage tank. The air inlet of the buffer tank is connected to the compressor outlet via a purification unit, and the air outlet of the buffer tank is connected to the air inlet of the main gas storage tank via a first electrically controlled valve. The air outlet of the main gas storage tank is connected to a pressure regulating unit. A pressure sensor is installed in both the buffer tank and the main gas storage tank. The control unit controls the filling and discharging of the buffer tank with a first pressure threshold range and controls the gas supply pressure of the main gas storage tank with a second pressure threshold range. The lower limit of the second pressure threshold range is higher than the lower limit of the first pressure threshold range.

10. The online oil chromatography monitoring system according to claim 1, characterized in that, The detection module is a gas chromatograph detector, and the carrier gas output by the self-generated carrier gas source module is purified air or nitrogen; the oil chromatography online monitoring system is used for the monitoring of dissolved gases in the main transformer oil of wind power plants.

Images