High-efficiency collecting device and method for extracting oil from transformer

Abstract

The invention relates to an efficient transformer oil extraction and collection device, belongs to the technical field of electrical equipment detection, solves the problems that an existing transformer oil collection device is low in oil extraction efficiency, inflexible in filtering precision switching, insufficient in automatic control and the like, and comprises an oil extraction pipeline system, a filtering system and a control system. The oil taking pipeline system is connected with the oil storage tank through an oil taking connector and a main oil conveying pipe. The main oil conveying pipe is provided with a first electromagnetic valve and a vacuum pump. The filtering system comprises a coarse filtering branch and a fine filtering branch which are connected in parallel, so that filtering with different precisions can be realized; the control system achieves intelligent control over the vacuum pump and the electromagnetic valve through a liquid level sensor, a flow speed sensor and a controller. The invention further relates to a transformer oil extraction method. The system is mainly used for efficient collection and processing of transformer oil, and automation and precision of the collection process are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment detection, and more particularly to a transformer oil extraction and collection device and method. Background Art

[0002] Transformers are critical equipment in power systems, and monitoring the oil status within them is crucial to equipment reliability. Regularly collecting transformer oil samples for comprehensive analysis of insulation properties, gas composition, and physical and chemical indicators is an important means of assessing transformer operating conditions. This allows for real-time monitoring of the transformer's operating status, proactively identifying potential faults, and preventing major accidents. Efficient, pollution-free oil extraction equipment is crucial for ensuring accurate test data and efficient operation and maintenance. However, existing transformer oil extraction systems present numerous challenges. Traditional oil extraction systems often rely on manual operation, resulting in low efficiency. Open-type oil extraction systems are prone to dust contamination (particle size >NAS 8), rendering oil sample detection ineffective. Furthermore, larger particulate impurities (such as metal debris, fibers, and rust) in transformer oil can easily clog filters and pipelines, reducing flow rate and impacting extraction efficiency. While small particles (such as insulating paint residue and colloidal contaminants) do not affect pipeline flow, they can significantly interfere with test results. Ensuring a smooth oil extraction process and preventing filter and pipeline blockage, thereby providing a dual guarantee for transformer safe operation, is a pressing technical challenge addressed in this application. Summary of the Invention

[0003] The present invention provides a high-efficiency transformer oil collection device, which can solve the problems of low oil collection efficiency, easy clogging of filter element pipelines, and insufficient automation control in existing transformer oil collection devices. By filtering mechanical impurities and removing interference factors, it can achieve efficient collection and processing of transformer oil, ensuring the automation and precision of the collection process.

[0004] The present invention provides a transformer oil extraction method, which can solve the problems of unclear process and inaccurate control in existing oil extraction methods, ensure oil extraction efficiency and oil sample quality, reduce the influence of human factors, and improve the reliability and accuracy of oil extraction work.

[0005] In order to achieve these purposes and other advantages according to the present invention, a transformer oil extraction and efficient collection device is provided, comprising: An oil extraction pipeline system includes an oil extraction interface, a main oil pipeline, and an oil storage tank connected in sequence. The oil extraction interface is used to connect to the oil extraction port of the transformer. The main oil pipeline is provided with a first solenoid valve for controlling oil circulation and a vacuum pump for providing power. The inlet end of the vacuum pump is connected to the oil extraction interface, and the outlet end of the vacuum pump is connected to the oil storage tank. A filtration system comprising a coarse filter branch and a fine filter branch arranged in parallel on a main oil pipeline, wherein the inlet ends of the coarse filter branch and the fine filter branch are connected in parallel to the main oil pipeline at the outlet end of the vacuum pump, and the outlet ends of the coarse filter branch and the fine filter branch merge and are connected to an oil storage tank. The coarse filter branch comprises a first branch pipe communicating with the main oil pipeline, wherein a second solenoid valve and a coarse filter are sequentially provided on the first branch pipe, and the filtration accuracy of the coarse filter is 50-100 μm. The fine filter branch comprises a second branch pipe communicating with the main oil pipeline, wherein a third solenoid valve and a fine filter are sequentially provided on the second branch pipe, and the filtration accuracy of the fine filter is 5-20 μm. Both the first branch pipe and the second branch pipe are connected to the oil storage tank via the main oil pipeline; A control system includes a controller, a liquid level sensor arranged in the oil storage tank, and a flow rate sensor arranged on the main oil pipeline downstream of the filtration system. The liquid level sensor and the flow rate sensor are both electrically connected to the controller, and the first solenoid valve, the second solenoid valve, the third solenoid valve and the vacuum pump are also electrically connected to the controller respectively. The controller is configured to control the start and stop of the vacuum pump according to the detection signal of the liquid level sensor, and to adjust the power of the vacuum pump according to the detection signal of the flow rate sensor. When coarse filtration is required, the controller controls the first solenoid valve and the second solenoid valve to open and the third solenoid valve to close. When fine filtration is required, the controller controls the first solenoid valve and the third solenoid valve to open and the second solenoid valve to close.

[0006] Preferably, the oil extraction interface is connected to the oil extraction port of the transformer through a universal quick-connect valve group, and the universal quick-connect valve group includes a metal conversion head, an elastic sealing sleeve, a strong magnetic ring and a threaded locking structure. The metal conversion head is provided with three specifications, which are conversion heads suitable for the oil extraction ports of Φ10 mm, Φ16 mm and Φ25 mm transformers respectively. The elastic sealing sleeve is provided with two materials, which are oil-resistant rubber sleeve and fluororubber sleeve respectively. The magnetic force of the strong magnetic ring is not less than 50 N, and the pitch of the threaded locking structure is 1.5 mm. The strong magnetic ring is used to pre-fix the metal conversion head on the oil extraction port of the transformer, and the threaded locking structure is used to thread the metal conversion head to the oil extraction port of the transformer and perform secondary sealing.

[0007] Preferably, it also includes: A vacuum sampling bottle assembly includes a sampling bottle and a sampling needle connected in sequence. The capacity of the sampling bottle is 100 mL or 250 mL. The sampling bottle is a sealed bottle pre-evacuated to -80 kPa. The sampling needle is arranged at the bottle mouth of the sampling bottle. The bottle mouth is provided with an on-off valve for connecting the sampling needle. The sampling needle is connected to the sampling tube through a flange quick-release interface, and then connected to the sampling port of the oil storage tank. The flange quick-release interface is a DN15 PN1.6 bottle mouth flange. An O-ring is provided on the bottle mouth flange. The flange quick-release interface is connected to the sampling tube through a snap-fit ​​structure, and the leakage rate is not greater than 0.1 mL / min.

[0008] Preferably, a pressure differential sensor is provided at the inlet and outlet ends of the coarse filter and the fine filter respectively, and the pressure differential sensor is electrically connected to the controller. A pre-filter is installed in series on the second branch pipe before the inlet of the fine filter, and the filtration accuracy of the pre-filter is 10-30 μm. The controller is preset with a pressure difference-flow rate correlation model, Q = Q 0× in, Q Indicates the real-time flow rate. Q 0 represents the initial flow rate, k Indicates the filter element clogging coefficient, Δ P Indicates the pressure difference, t Indicates the running time; If the coarse filter branch is currently in use, when it is detected k >5×10 -5 MPa -1 s -1 When , it automatically switches to the fine filter branch; If the fine filter branch is currently in use, when it is detected k >2.5×10 -5 MPa -1 s -1 When the alarm stops,

[0009] Preferably, a pressure differential sensor is provided at the inlet and outlet ends of the coarse filter and the fine filter, respectively, and the pressure differential sensor is electrically connected to the controller. The coarse filter and the fine filter are both provided with a backwash circuit, and the backwash circuit includes a third branch pipe connected to the outlet end of the coarse filter and a fourth branch pipe connected to the outlet end of the fine filter. A fourth solenoid valve and a fifth solenoid valve are provided on the third branch pipe and the fourth branch pipe, respectively. The third branch pipe and the fourth branch pipe are both directly connected to the main oil pipeline upstream of the vacuum pump through the backwash main pipe. The third branch pipe and the fourth branch pipe are independently connected to the sewage tank through the seventh solenoid valve. An independent oil drainage pipeline is provided at the bottom of the sewage tank. A sixth solenoid valve is provided on the independent oil drainage pipeline. The controller is configured to perform the following operations in sequence when the flow rate sensor detects that the flow rate in the main oil pipeline drops by more than 20% and the pressure difference exceeds 0.05 MPa: closing the first solenoid valve, the second solenoid valve, and the third solenoid valve; Start the vacuum pump; Open the fourth solenoid valve or the fifth solenoid valve of the corresponding branch, and the seventh solenoid valve of the corresponding branch; Maintain the backwash state for 30-60 seconds, during which the vacuum pump power dynamically maintains the pressure of the backwash main pipe within the range of 0.1-0.15 MPa; Close the fourth solenoid valve or the fifth solenoid valve, or the seventh solenoid valve; Open the sixth solenoid valve to discharge the dirty oil in the sewage tank.

[0010] It is preferred to maintain hierarchical control of backwash conditions: Phase 1: The controller reduces the vacuum pump power to 30-40% of the rated value and triggers the vibration system to backflush for 30 seconds. The vibration system includes a piezoelectric ceramic sheet mounted on the surface of the coarse filter and fine filter housings. The piezoelectric ceramic sheet is connected to a high-frequency power supply, which activates the piezoelectric ceramic sheet to generate 28 kHz ultrasonic vibration with an amplitude of 50 μm. The contact surface between the piezoelectric ceramic sheet and the filter housing is filled with thermal grease. A temperature sensor monitors the filter temperature in real time and shuts off the ultrasonic power supply when the temperature exceeds 80°C. If the pressure difference does not drop by 40% after the first stage, the second stage will begin; Phase 2: The controller increases the vacuum pump power to 40-50% of the rated value and simultaneously triggers the pulse gas system to backflush for 15 seconds. The pulse gas circuit system includes an air storage tank, a pulse solenoid valve and a pressure sensor arranged on the backwash main pipe. The air storage tank is pre-filled with nitrogen to 0.2-0.5 MPa. The controller opens / closes the pulse solenoid valve at a frequency of 1-3 Hz, so that the high-pressure nitrogen and oil are mixed to form a pulse jet, which impacts the interior of the filter element. Each pulse lasts 50-100 ms. The third stage: Shut down the pulse gas system, and the controller reduces the vacuum pump power to 30-40% of the rated value, and backwashes for 15 seconds.

[0011] Preferably, For the coarse filter, the pulse air pressure is set to 0.2-0.3 MPa and the frequency is 1-2 Hz; For the fine filter, the pulse air pressure is set to 0.3-0.5 MPa and the frequency is 2-3 Hz.

[0012] A transformer oil extraction method, based on the device, comprises: Connect the transformer oil outlet and the oil outlet port through the universal quick-connect valve group, open the first solenoid valve and the vacuum pump, so that the transformer oil is sucked into the main oil pipeline through the oil outlet port to create a negative pressure environment; Select the coarse filtration or fine filtration mode. In the coarse filtration mode, the first and second solenoid valves are opened, and the third solenoid valve is closed. The oil flows into the oil storage tank through the coarse filter. In the fine filtration mode, the first and third solenoid valves are opened, and the second solenoid valve is closed. The oil flows into the oil storage tank through the fine filter. Start and stop the vacuum pump according to the liquid level signal of the oil tank, monitor the liquid level of the oil tank in real time, and when the liquid level reaches the upper limit H max Turn off the vacuum pump; The vacuum pump power is dynamically adjusted according to the flow rate signal of the main oil pipeline. When the real-time flow rate is less than 80% of the initial flow rate, the vacuum pump power is increased by 20%. When the real-time flow rate is greater than 120% of the initial flow rate, the vacuum pump power is reduced by 15%. The initial flow rate is the average flow rate within 10 minutes after the system first runs stably. Connect the sampling bottle that has been pre-evacuated to -80 kPa to the sampling port of the oil storage tank; Open the on-off valve and control the oil sample to be injected into the sampling bottle at a flow rate of 20-50 mL / min.

[0013] Preferably, a pressure differential sensor is provided at the inlet and outlet ends of the coarse filter and the fine filter respectively, and the pressure differential sensor is electrically connected to the controller. A pre-filter is installed in series on the second branch pipe before the inlet of the fine filter, and the filtration accuracy of the pre-filter is 10-30 μm. The controller is preset with a pressure difference-flow rate correlation model, Q = Q 0× in, Q Indicates the real-time flow rate. Q 0 represents the initial flow rate, k Indicates the filter element clogging coefficient, Δ P Indicates the pressure difference, t Indicates the running time; Calculate the filter element clogging coefficient in real time. k >5×10 -5 MPa -1 s -1 When k>2.5×10 - 5 MPa -1 s -1 When the alarm stops, the machine will sound an audible and visual alarm.

[0014] Preferably, When the flow rate in the main oil pipeline drops by more than 20% and the pressure difference exceeds 0.05 MPa, the first, second and third solenoid valves are closed, the vacuum pump is started, the fourth or fifth solenoid valve of the corresponding branch, and the seventh solenoid valve of the corresponding branch are opened, and the backwash program is started. The backwash state is maintained for 30-60 seconds, and the vacuum pump power is dynamically maintained to maintain the backwash main pipe pressure at 0.1-0.15 MPa; Phase 1: The controller reduces the vacuum pump power to 30-40% of the rated value and triggers the vibration system to perform backwashing for 30 seconds. If the pressure difference does not drop by 40% after the first phase, the second phase begins. The second stage: The controller increases the vacuum pump power to 40-50% of the rated value and triggers the pulse air system at the same time, backwashing for 15 seconds. For the coarse filter, the pulse air pressure is set to 0.2-0.3 MPa, the frequency is 1-2 Hz, for the fine filter, the pulse air pressure is set to 0.3-0.5 MPa, the frequency is 2-3 Hz, and the duration of each pulse is 50-100 ms. The third stage: the pulse gas system is turned off, the controller reduces the vacuum pump power to 30-40% of the rated value, and reverse flushes for 15 seconds; Close the fourth solenoid valve or the fifth solenoid valve, the seventh solenoid valve, and open the sixth solenoid valve to drain the dirty oil in the drain tank. During the oil discharge, nitrogen is introduced into the drain tank for purge at a purge flow rate of 10 L / min.

[0015] The present invention has at least the following beneficial effects: First, the present invention can automatically establish negative pressure and control the flow of oil by combining the oil extraction pipeline system with a vacuum pump and a solenoid valve. Combined with the oil tank liquid level and flow rate monitoring, it avoids manual operation lags and improves the continuity of oil extraction. The coarse and fine filter branches of the filtration system are connected in parallel, and different precision filtration is achieved through solenoid valve switching to meet diverse detection needs. The multi-specification conversion heads and double sealing design of the universal quick-connect valve group can quickly adapt to oil extraction ports of different calibers, with convenient connection and strong sealing. The pre-vacuum and quick-release interface design of the vacuum sampling bottle assembly ensures that the sampling process is leak-free and pollution-free. The overall structure reduces manual intervention, improves work efficiency and oil sample collection reliability.

[0016] Second, the present invention achieves intelligent switching of filter branches and fault warnings by calculating the filter element blockage status in real time. If the coarse filter branch becomes clogged, it automatically switches to the fine filter branch. If the fine filter branch is at risk of blockage, the system shuts down and issues an alarm, eliminating the need for manual monitoring of pressure differentials and flow rate fluctuations. This model relies on sensors and controllers to promptly detect filter element anomalies, preventing oil extraction interruptions and sample contamination caused by blockage, ensuring the continuous and effective operation of the filtration system. It is suitable for scenarios requiring a high degree of automation.

[0017] Third, this invention improves filter element maintenance efficiency through graded and staged control, combined with ultrasonic vibration and pulsed air path technology. When a blockage is detected, the system automatically initiates backwashing, removing impurities from the filter element surface and deep within the filter element in stages. Flushing parameters are tailored to the different characteristics of the coarse and fine filters to avoid damage to the filter element. This design effectively reduces the frequency of filter element replacement, lowers maintenance costs, ensures the long-term stable operation of the filtration system, and ensures that contaminated oil is completely discharged during the backwash process, avoiding secondary contamination.

[0018] Fourth, the oil extraction method of the present invention ensures accurate execution of each link through standardized processes and automated control. The connection link is quickly sealed, and the vacuum pump is automatically started and stopped according to the liquid level and the flow rate is dynamically adjusted during oil extraction. The sampling link controls the injection speed to avoid contamination. The backwash program is embedded in the process, and the filter element is automatically cleaned when blocked, and nitrogen purge is used to ensure complete sewage discharge. This method converts manual operation into automatic control, improves the standardization of the oil extraction process, reduces the influence of human factors, and is suitable for detection scenarios with strict requirements on oil sample quality, ensuring the reliability of the test results.

[0019] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described below in detail with reference to the description so that those skilled in the art can implement the invention accordingly.

[0021] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0022] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified, and therefore should not be construed as limiting the present invention.

[0023] The existing device is cumbersome to operate manually during the oil extraction process, and the filter element is easily clogged during use, resulting in a decrease in flow rate and affecting the oil extraction efficiency. However, it lacks an effective blockage detection and filtering mechanism, and the control system cannot accurately control the liquid level and flow rate in real time, resulting in low oil extraction efficiency and failing to meet the requirements of efficient and accurate oil extraction. The present invention provides a transformer oil extraction and collection device with high efficiency, comprising: An oil extraction pipeline system includes an oil extraction interface, a main oil pipeline, and an oil storage tank connected in sequence. The oil extraction interface is used to connect to the oil extraction port of the transformer and is sequentially connected to the oil storage tank through the main oil pipeline. The main oil pipeline is used to transmit oil, and the oil storage tank stores the collected oil. The main oil pipeline is provided with a first solenoid valve for controlling the circulation of the oil and a vacuum pump for providing power. The inlet end of the vacuum pump is connected to the oil extraction interface, and the outlet end of the vacuum pump is connected to the oil storage tank, so that transformer oil can be sucked from the transformer into the main oil pipeline and transported to the oil storage tank. The filtration system includes a coarse filter branch and a fine filter branch arranged in parallel on the main oil pipeline. It only targets mechanical impurities (solid particles) and does not change the chemical composition, dissolved gas or moisture content of the oil. It will not have a negative impact on the test results. Instead, it improves the credibility of the data by removing interference factors. It flexibly switches between coarse and fine filtration according to actual needs to meet the requirements of different test items for oil sample purity. The inlet ends of the coarse filter branch and the fine filter branch are connected in parallel to the main oil pipeline at the outlet end of the vacuum pump. The outlet ends of the coarse filter branch and the fine filter branch are connected to the oil storage tank after merging. The coarse filter branch includes a first branch connected to the main oil pipeline. The first branch is sequentially provided with a second solenoid valve and a coarse filter. The second solenoid valve is used to control the on and off of the branch. The filtration accuracy of the coarse filter is 50-100 μm, used for preliminary filtration of the oil, a folded metal mesh filter element can be used, the fine filtration branch includes a second branch pipe connected to the main oil pipeline, the second branch pipe is sequentially provided with a third solenoid valve and a fine filter, the third solenoid valve is used to control the on and off of the branch, the fine filter has a filtration accuracy of 5-20 μm, is used for fine filtration of the oil, and a polypropylene melt-blown filter element can be used, the first branch pipe and the second branch pipe are both connected to the oil storage tank through the main oil pipeline, so that the oil enters the oil storage tank after filtration; The control system includes a controller, a liquid level sensor arranged in the oil storage tank and a flow rate sensor arranged on the main oil pipeline downstream of the filtration system. The controller adopts an industrial-grade PLC controller. The liquid level sensor is used to detect the oil level in the oil storage tank and transmit the detection signal to the controller. The vacuum pump is automatically started and stopped according to the liquid level to avoid overflow of the oil storage tank or interruption of oil extraction. The flow rate sensor is used to detect the flow rate of the oil in the main oil pipeline and also transmits the detection signal to the controller to dynamically adjust the power of the vacuum pump to maintain a stable oil extraction speed and ensure the stability and efficiency of the oil extraction process. The liquid level sensor and the flow rate sensor are both electrically connected to the controller. The controller accurately controls the vacuum pump and the solenoid valve according to the liquid level of the oil storage tank and the flow rate in the pipeline in real time. The first solenoid valve The valve, the second solenoid valve, the third solenoid valve and the vacuum pump are also electrically connected to the controller respectively. The controller is configured to control the start and stop of the vacuum pump according to the detection signal of the liquid level sensor, shut down the vacuum pump when the liquid level reaches the upper limit value, and restart it when it drops to the lower limit value, and adjust the power of the vacuum pump according to the detection signal of the flow rate sensor to maintain a stable flow rate. When coarse filtration is required, the controller controls the first solenoid valve and the second solenoid valve to open and the third solenoid valve to close, and the oil is filtered through the coarse filtration branch. When fine filtration is required, the controller controls the first solenoid valve and the third solenoid valve to open and the second solenoid valve to close, and the oil is filtered through the fine filtration branch, thereby realizing automatic control of the oil extraction process and flexible switching of the filtration mode.

[0024] The above technical solution achieves efficient transformer oil collection by installing an oil extraction pipeline system, a filtration system, and a control system. The vacuum pump in the oil extraction pipeline system provides power, ensuring rapid oil flow. The coarse and fine filtration branches of the filtration system can be flexibly switched according to demand to meet the required oil sample purity. The control system achieves automated control through sensors and controllers, automatically starting and stopping the vacuum pump according to the liquid level and dynamically adjusting the power according to the flow rate. This improves the stability and efficiency of the oil extraction process, reduces manual operations, and reduces labor intensity.

[0025] The traditional connection method requires a variety of interfaces for oil extraction ports of different specifications, which is inconvenient to replace and has poor sealing effect, which can easily lead to oil leakage or contamination, affecting the smooth progress of oil extraction and the accuracy of oil samples. In another technical solution, the oil extraction interface is connected to the oil extraction port of the transformer through a universal quick-connect valve group. The universal quick-connect valve group includes a metal conversion head, an elastic sealing sleeve, a strong magnetic ring and a threaded locking structure. The metal conversion head is provided with three specifications, which are respectively adapted to the oil extraction ports of Φ10 mm, Φ16 mm, and Φ25 mm transformers to meet the connection requirements of oil extraction ports of different specifications. The elastic sealing sleeve is provided with two materials, namely oil-resistant rubber sleeve and fluororubber sleeve. The appropriate material can be selected according to the characteristics of the transformer oil and the use environment to ensure the sealing effect. The oil-resistant rubber sleeve is suitable for general transformer oil environment, and the fluororubber sleeve is suitable for high temperature and highly corrosive special oil environment. The magnetic force of the strong magnetic ring is not less than 50 N, and neodymium iron boron permanent magnet material is selected. The pitch of the threaded locking structure is 1.5 The strong magnetic ring is used to pre-fix the metal adapter to the transformer's oil outlet, facilitating subsequent threaded connections and reducing the difficulty of manual alignment. After the strong magnetic ring is pre-fixed, the threaded locking structure is used to thread the metal adapter to the transformer's oil outlet and perform a secondary seal to ensure the connection's tightness and prevent oil leakage. When connecting, first select the appropriate metal adapter and elastic sealing sleeve based on the specifications of the transformer's oil outlet. Install the elastic sealing sleeve on the metal adapter, then use the strong magnetic ring to adsorb the metal adapter to the oil outlet. After alignment, tighten it using the threaded locking structure to achieve a reliable connection.

[0026] In the above technical solution, the setting of the universal quick-connect valve group enables the oil extraction interface to adapt to transformer oil extraction ports of various specifications. The three specifications of the metal conversion head and the two materials of the elastic sealing sleeve meet different needs. The pre-fixation of the strong magnetic ring and the secondary sealing of the threaded locking structure ensure the convenience and sealing of the connection, avoid oil leakage and contamination, and improve the efficiency and reliability of the oil extraction work.

[0027] The connection between the traditional sampling bottle and the oil extraction device is not sealed enough, which can easily lead to oil sample contamination or leakage, affecting the accuracy of the test results. At the same time, the sampling process lacks precise control of the flow rate, which affects the collection and storage of oil samples. In another technical solution, it also includes: The vacuum sampling bottle assembly includes a sampling bottle and a sampling needle connected in sequence. The capacity of the sampling bottle is 100 mL or 250 mL. The sampling bottle of appropriate capacity can be selected according to the detection requirements. The sampling bottle is a sealed bottle pre-evacuated to -80 kPa. It can form a negative pressure during sampling to attract oil into the sampling bottle. The sampling needle is arranged at the bottle mouth of the sampling bottle. The bottle mouth is provided with an on-off valve for connecting the sampling needle. The sampling process is controlled by controlling the opening and closing of the on-off valve. The sampling needle is connected to the sampling tube through a flange quick-release interface, and then connected to the sampling port of the oil storage tank. The flange quick-release interface is a DN15 PN1.6 bottle mouth flange. An O-ring is provided on the bottle mouth flange to enhance the sealing effect. The flange quick-release interface is connected to the sampling tube through a snap-on structure. The snap-on can be made of stainless steel spring snap-on to ensure the convenience and sealing of the connection. The leakage rate is not greater than 0.1 mL / min, ensuring that the oil sample will not leak during the sampling process and ensuring the accuracy of the test results. When in use, connect the pre-vacuumed sampling bottle to the sampling tube through the flange quick-release interface, open the on-off valve, and the oil in the oil storage tank enters the sampling bottle under the action of vacuum pressure. Control the oil sample to be injected into the sampling bottle at an appropriate flow rate. After sampling is completed, close the on-off valve and remove the sampling bottle.

[0028] In the above technical solution, the pre-vacuumed sampling bottle of the vacuum sampling bottle assembly and the flange quick-release interface of specific specifications ensure the sealing and convenience of the sampling process. Sampling bottles of different capacities meet different testing requirements. The snap-on structure and low leakage rate ensure the accurate collection and preservation of oil samples, thereby improving the reliability of the test results.

[0029] Filter blockage can lead to reduced oil extraction efficiency and equipment damage. Existing devices are unable to detect filter blockage in a timely manner and take appropriate measures. In another technical solution, differential pressure sensors are respectively installed at the inlet and outlet of the coarse filter and the fine filter. The differential pressure sensors are electrically connected to the controller. A pre-filter with a filtration accuracy of 10-30 μm is installed in series on the second branch pipe before the inlet of the fine filter. The controller is pre-set with a pressure difference-flow rate correlation model. Q = Q 0× in, Q Indicates the real-time flow rate. Q 0 represents the initial flow rate, the initial flow rate Q 0 is the average flow rate within 10 minutes after the system first runs steadily. k Indicates the filter element clogging coefficient, Δ P Indicates the pressure difference, t Indicates the running time; During the operation of the device, the flow rate sensor detects the flow rate in the main oil pipeline in real timeQ , the differential pressure sensor detects the pressure difference Δ at the inlet and outlet of the filter element P The controller calculates the filter element clogging coefficient in real time based on these data k , If the coarse filter branch is currently in use, when it is detected k >5×10 -5 MPa -1 s -1 When the filter is blocked, it indicates that the coarse filter is blocked to an extent that affects normal operation. The controller will automatically close the second solenoid valve and open the third solenoid valve, automatically switching to the fine filter branch to ensure that the oil extraction process continues. If the fine filter branch is currently in use, when it is detected k >2.5×10 -5 MPa -1 s -1 If the fine filter is blocked, it means that continuing to operate the fine filter may cause blockage risk, which may cause equipment damage. The controller will alarm in advance to remind the staff to perform maintenance.

[0030] In the above technical solution, the application of the pressure difference-flow rate correlation model realizes real-time monitoring and automatic judgment of the filter element blockage coefficient. It can switch the filter branch or shut down the alarm in time according to the blockage situation, avoiding the decrease in oil extraction efficiency and equipment damage caused by filter element blockage, and improving the intelligence level and reliability of the filtration system.

[0031] Impurities on the filter element can cause the filter element to become clogged. Existing devices do not backwash in a timely manner and cannot effectively remove impurities on the filter element, which shortens the service life of the filter element and increases the frequency and cost of replacing the filter element. In another technical solution, differential pressure sensors are respectively provided at the inlet and outlet ends of the coarse filter and the fine filter. The differential pressure sensors are electrically connected to the controller to transmit differential pressure data in real time. The coarse filter and the fine filter are both provided with a backwash circuit. The backwash circuit includes a third branch pipe connected to the outlet end of the coarse filter and a fourth branch pipe connected to the outlet end of the fine filter. A fourth solenoid valve and a fifth solenoid valve are respectively provided on the third branch pipe and the fourth branch pipe to control the on and off of the backwash circuit. A one-way valve can also be installed on the backwash main pipe. To prevent oil backflow, the third branch pipe and the fourth branch pipe are directly connected to the main oil pipeline upstream of the vacuum pump through the backwash main pipe to form a backwash path. A three-way pipe fitting can be provided at the connection point. The third branch pipe and the fourth branch pipe are independently connected to the sewage tank through the seventh solenoid valve. An independent oil drainage pipe is provided at the bottom of the sewage tank. A sixth solenoid valve is provided on the independent oil drainage pipe to discharge the dirty oil in the sewage tank. The controller is configured to, when the flow rate sensor detects that the flow rate in the main oil pipeline drops by more than 20% and the pressure difference exceeds 0.05 MPa, it indicates that the filter element is clogged and needs backwashing, and the following operations are performed in sequence: Close the first solenoid valve, the second solenoid valve and the third solenoid valve to stop the normal oil extraction process; Start the vacuum pump to provide power for backwashing; Open the fourth solenoid valve or the fifth solenoid valve of the corresponding branch, as well as the seventh solenoid valve of the corresponding branch, so that the backwashing oil flows from the backwashing main pipe through the third branch pipe or the fourth branch pipe into the coarse filter or the fine filter, reversely flushing the filter element, and impurities enter the sewage tank along with the oil; Maintain the backwash state for 30-60 seconds, during which the vacuum pump power dynamically maintains the pressure of the backwash main pipe within the range of 0.1-0.15 MPa; Close the fourth solenoid valve or the fifth solenoid valve, or the seventh solenoid valve to stop backwashing; Open the sixth solenoid valve to discharge the dirty oil in the sewage tank.

[0032] In this technical solution, the backwash circuit and controller work together to automatically initiate a backwash sequence when the filter element becomes clogged, removing impurities from the filter element, extending its service life, reducing replacement frequency, and lowering maintenance costs. Parameter control during the backwash process ensures effective backwashing and improves the stability and long-term operational capability of the filtration system.

[0033] The existing device has a single backwash process, which is difficult to deal with different degrees of blockage, affecting the long-term stable operation of the filtration system. In another technical solution, the backwash state is maintained in a graded control manner: Phase 1: The filter element is initially cleaned through low-power backwashing and ultrasonic vibration. The controller reduces the vacuum pump power to 30-40% of the rated value and triggers the vibration system to backwash for 30 seconds. The vibration system includes a piezoelectric ceramic sheet mounted on the surface of the coarse filter and fine filter housings. The piezoelectric ceramic sheet is connected to a high-frequency power supply, which activates the piezoelectric ceramic sheet to generate 28 kHz ultrasonic vibrations with an amplitude of 50 μm. The contact surface between the piezoelectric ceramic sheet and the filter housing is filled with thermal grease with a thermal conductivity of 1.5-2 W / (m·K) to improve heat dissipation. A temperature sensor monitors the filter element temperature in real time and shuts off the ultrasonic power supply when it exceeds 80°C to prevent overheating and damage to the equipment. If the pressure difference does not drop by 40% after the first stage, the second stage will begin; Phase 2: The controller increases the vacuum pump power to 40-50% of the rated value and simultaneously triggers the pulse gas system to backflush for 15 seconds. The pulse gas circuit system includes an air storage tank, a pulse solenoid valve, and a pressure sensor arranged on the backwash main pipe. The air storage tank is pre-filled with nitrogen to 0.2-0.5 MPa. The controller opens / closes the pulse solenoid valve at a frequency of 1-3 Hz. The diameter of the pulse solenoid valve can be selected to match the diameter of the backwash branch pipe, so that the high-pressure nitrogen and oil are mixed to form a pulse jet, which impacts the interior of the filter element. Each pulse lasts for 50-100 ms. The impact force of the pulse jet further removes stubborn impurities on the filter element. The third stage: Shut down the pulse gas system, the controller reduces the vacuum pump power to 30-40% of the rated value, reverse flushes for 15 seconds, and performs a final cleaning of the filter element to ensure that impurities are fully removed.

[0034] In the above technical solution, the backwash process is controlled in stages, and combined with the vibration system and the pulse air system, different backwash strategies are adopted for different degrees of blockage, thereby improving the backwash efficiency and effect, being able to more effectively remove impurities on the filter element, ensuring the normal operation of the filtration system, and reducing manual intervention.

[0035] The existing device has a unified backwash parameter and cannot adapt to different filter elements. In another technical solution, different pulse air pressure and frequency are set according to the different filtration accuracy and clogging conditions of the coarse filter and fine filter: For the coarse filter, due to its low filtration accuracy and large filter element pore size, the degree of clogging is relatively light. The pulse air pressure is set to 0.2-0.3 MPa and the frequency is 1-2 Hz, which can ensure a certain impact force to remove impurities without causing excessive pressure on the coarse filter. For fine filters, the filtration accuracy is higher and the filter element pore size is smaller, which is prone to serious blockage and requires greater impact force. The pulse air pressure is set to 0.3-0.5 MPa and the frequency is 2-3 Hz. A stronger pulse jet is formed with higher air pressure and frequency to effectively remove fine impurities on the fine filter element and ensure the normal operation of the fine filter.

[0036] In the above technical solution, different pulse air pressures and frequencies are set according to the different characteristics of the coarse filter and the fine filter to achieve precise backwashing, improve adaptability to different filter elements, further enhance the backwashing effect, ensure that both the coarse filter and the fine filter branches can be effectively maintained, and extend the service life of the filter element.

[0037] The existing oil extraction method has unclear procedures and imprecise control. This application provides a transformer oil extraction method based on the device, which includes: Connect the transformer oil outlet and the oil outlet interface through a universal quick-connect valve assembly. Select a suitable metal adapter and elastic sealing sleeve according to the specifications of the transformer oil outlet. Use a strong magnetic ring to pre-fix and then use a threaded locking structure for secondary sealing to ensure a reliable connection and good sealing. Open the first solenoid valve and vacuum pump. The vacuum pump starts working and can suck the transformer oil into the main oil pipeline through the oil outlet interface within 5-10 seconds, creating a negative pressure environment and promoting oil flow. Select the coarse filtration or fine filtration mode. If the coarse filtration mode is selected, the first and second solenoid valves are opened, and the third solenoid valve is closed. The oil enters the oil storage tank through the coarse filter and filters out impurities with a particle size of 50-100 μm. If the fine filtration mode is selected, the first and third solenoid valves are opened, and the second solenoid valve is closed. The oil enters the oil storage tank through the fine filter and filters out impurities with a particle size of 5-20 μm. During the oil extraction process, the oil tank level is monitored in real time, and the vacuum pump is started and stopped according to the oil tank level signal. When the level reaches the upper limit H max Shut down the vacuum pump to prevent the oil tank from overflowing. min When the oil is pumped out, restart the vacuum pump and continue to pump oil to ensure the continuity of the oil pumping process; Dynamically adjust the vacuum pump power according to the flow rate signal of the main oil pipeline. When the real-time flow rate is less than 80% of the initial flow rate, it means the flow rate is too low. Increase the vacuum pump power by 20% to increase the flow rate. When the real-time flow rate is greater than 120% of the initial flow rate, the flow rate is too high. Reduce the vacuum pump power by 15% to maintain a stable flow rate. The initial flow rate is the average flow rate within 10 minutes after the system first runs stably. Connect the sampling bottle that has been pre-evacuated to -80 kPa to the sampling port of the oil storage tank; Open the on-off valve and control the oil sample to be injected into the sampling bottle at a flow rate of 20-50 mL / min to ensure that the sampling speed meets the detection requirements. After sampling is completed, close the on-off valve and remove the sampling bottle.

[0038] In the above technical solution, clear oil extraction method steps and control strategies are implemented to achieve standardization and automation of the oil extraction process. There are specific operation and control methods for each link from connection to sampling, which ensures the oil extraction efficiency and oil sample quality, reduces the impact of human factors, and improves the reliability and accuracy of the oil extraction work.

[0039] The existing oil extraction method cannot intelligently adjust the filtration mode according to the filter element blockage and make corresponding treatment. In another technical solution, the inlet and outlet ends of the coarse filter and the fine filter are respectively provided with a pressure differential sensor, which is electrically connected to the controller. A pre-filter is installed in series on the second branch pipe before the inlet of the fine filter. The filtration accuracy of the pre-filter is 10-30 μm. The controller is preset with a pressure difference-flow rate correlation model, Q = Q 0× in, Q Indicates the real-time flow rate. Q 0 represents the initial flow rate, the initial flow rate Q 0 is the average flow rate within 10 minutes after the system first runs steadily. k Indicates the filter element clogging coefficient, Δ P Indicates the pressure difference, t Indicates the running time; During the oil extraction process, the flow rate of the main oil pipeline and the pressure difference data of the filter inlet and outlet are collected in real time. P , real-time calculation of filter element clogging coefficient k , when in coarse filter mode k >5×10 -5 MPa -1 s -1 When the coarse filter is blocked and has affected the normal filtration, the controller automatically closes the second solenoid valve and opens the third solenoid valve to switch to the fine filter branch. If the fine filter branch is currently in use, when it detects k>2.5×10 -5 MPa -1 s -1 If the fine filter is continued to operate, there is a risk of clogging, which may cause damage to the equipment and the controller will alarm in advance.

[0040] In the above technical solution, a pressure difference-flow rate correlation model is applied in the oil extraction method to realize intelligent switching of the filter branch, and timely adjustment is made according to the blockage of the filter element to ensure the continuity and efficiency of the oil extraction process, avoid oil extraction interruption and efficiency reduction caused by filter element blockage, and improve the intelligence level of the entire oil extraction system.

[0041] The existing backwashing method has unclear steps and imprecise parameter control. In another technical solution, When the flow rate in the main oil pipeline drops by more than 20% and the pressure difference exceeds 0.05 MPa, the backwash program is started, the first solenoid valve, the second solenoid valve and the third solenoid valve are closed, normal oil extraction is stopped, the vacuum pump is started to provide power for backwashing, the fourth solenoid valve or the fifth solenoid valve of the corresponding branch, and the seventh solenoid valve of the corresponding branch are opened, and the backwash program is started. The backwash state is maintained for 30-60 seconds, and the vacuum pump power dynamically maintains the backwash main pipe pressure at 0.1-0.15 MPa; Phase 1: The controller reduces the vacuum pump power to 30-40% of the rated value and triggers the vibration system to perform backwashing for 30 seconds. If the pressure difference does not drop by 40% after the first phase, the second phase begins. The second stage: The controller increases the vacuum pump power to 40-50% of the rated value, and at the same time triggers the pulse air system to backwash for 15 seconds. The corresponding pulse air pressure and frequency are set according to the difference between the coarse filter and the fine filter. For the coarse filter, the pulse air pressure is set to 0.2-0.3 MPa and the frequency is 1-2 Hz. For the fine filter, the pulse air pressure is set to 0.3-0.5 MPa and the frequency is 2-3 Hz. The duration of each pulse is 50-100 ms. The third stage: the pulse gas system is turned off, the controller reduces the vacuum pump power to 30-40% of the rated value, and reverse flushes for 15 seconds; After the backwash is completed, close the fourth solenoid valve or the fifth solenoid valve, the seventh solenoid valve, and open the sixth solenoid valve to discharge the dirty oil in the drain tank. During the oil discharge, nitrogen is introduced into the drain tank for purging at a flow rate of 10 L / min to ensure that the dirty oil is completely removed and reduce residual impurities.

[0042] In the above technical solution, a complete backwash procedure and parameter control ensure the effectiveness and accuracy of the backwash process. Nitrogen purge further removes the dirty oil in the drain tank, improves the cleanliness of the backwash, reduces residual impurities, protects the filter element and the entire filtration system, extends the service life of the equipment, and reduces maintenance costs.

[0043] In one example, a substation regularly collected oil samples from a 10MVA oil-immersed transformer. The operator selected the device's universal quick-connect valve assembly, chose a metal adapter based on the transformer's oil outlet (Ø16mm), and paired it with an oil-resistant rubber elastic sealing sleeve. The adapter was pre-attached to the outlet using a strong magnetic ring, and the threaded locking mechanism was tightened clockwise to ensure a smooth connection and a secure seal.

[0044] The operator selects "coarse filtration mode" on the control system panel. The controller (an industrial-grade PLC) simultaneously activates the first solenoid valve and the vacuum pump. Once the vacuum pump is activated, negative pressure quickly builds up in the main oil pipeline. Transformer oil is drawn into the pipeline through the oil extraction port, where it passes through a coarse filter to remove impurities larger than 50 μm. The oil then enters the oil storage tank.

[0045] When the oil in the oil storage tank stabilizes, the operator opens the ball valve on the mouth of the sampling bottle, and the oil sample is injected into the sampling bottle under the action of vacuum pressure difference. The 100 mL sampling bottle completes the collection in about 3.3 minutes. After closing the valve, the sampling bottle is removed to ensure that the oil sample is leak-free and not contaminated by the outside world.

[0046] During the whole process, the controller monitors the filter element blockage in real time. Calculate the blockage coefficient k , k Continue to rise to 5×10 - 5 MPa -1 s -1 The controller automatically closes the second solenoid valve, opens the third solenoid valve, and switches to the fine filter branch. The oil continues to be filtered through a 30 μm pre-filter and a 10 μm fine filter to ensure that subsequent oil samples meet high-precision detection requirements.

[0047] The traditional process uses manual valves to control the flow of oil, observes the liquid level in the oil storage tank to start and stop the oil pump, and the oil extraction interface is directly connected to the transformer oil extraction port using threads. The filtration system is equipped with a coarse filter with an accuracy of 100 μm. There is no backwash system. The sampling bottle is an ordinary glass bottle that is not pre-vacuumed and relies on positive pressure from the oil pump for oil injection.

[0048] The experimental results are shown in Table 1.

[0049] Table 1 index Traditional crafts The present invention Improvement Single fuel extraction time 15 minutes 3 minutes 80% Particle pollution level NAS Level 8 NAS Level 4 50% Oil sample qualification rate 70% 98% 40% Oil leakage 50-100 mL ≤1 mL 99% Compared with traditional processes, the present invention has achieved significant improvements in multiple indicators. The time required for a single oil extraction has been reduced from 15 minutes to 3 minutes, an improvement of 80%. This is mainly due to the control system's automated control of the vacuum pump and solenoid valve, as well as the convenient connection design of the universal quick-connect valve group, which reduces manual operation and waiting time. The particle contamination level has been reduced from NAS level 8 to NAS level 4, an improvement of 50%. By relying on the parallel setting of the coarse and fine filter branches and the backwashing process, filtration of different precisions is achieved and impurities in the filter element are removed in a timely manner to ensure oil cleanliness. The oil sample qualification rate has increased from 70% to 98%, an increase of 40%, thanks to the sealing design of the entire process and the precise control of the sampling flow rate, which avoids oil sample contamination and leakage. The oil leakage volume has been reduced from 50-100 mL to ≤1 mL, an improvement of 99%. The strong magnetic pre-fixation and threaded secondary sealing of the universal quick-connect valve group, as well as the sealed connection of the sampling bottle, ensure high sealing during the connection and sampling process. These improvements reflect the significant advantages of the present invention in oil extraction efficiency, oil sample quality, and reliability.

[0050] The number of devices and processing scales described herein are intended to simplify the description of the present invention. Applications, modifications, and variations of the present invention will be readily apparent to those skilled in the art.

[0051] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. Transformer oil extraction and efficient collection device, characterized in that: include: An oil extraction pipeline system includes an oil extraction interface, a main oil pipeline, and an oil storage tank connected in sequence. The oil extraction interface is used to connect to the oil extraction port of the transformer. The main oil pipeline is provided with a first solenoid valve for controlling oil circulation and a vacuum pump for providing power. The inlet end of the vacuum pump is connected to the oil extraction interface, and the outlet end of the vacuum pump is connected to the oil storage tank. A filtration system comprising a coarse filter branch and a fine filter branch arranged in parallel on a main oil pipeline, wherein the inlet ends of the coarse filter branch and the fine filter branch are connected in parallel to the main oil pipeline at the outlet end of the vacuum pump, and the outlet ends of the coarse filter branch and the fine filter branch merge and are connected to an oil storage tank. The coarse filter branch comprises a first branch pipe communicating with the main oil pipeline, wherein a second solenoid valve and a coarse filter are sequentially provided on the first branch pipe, and the filtration accuracy of the coarse filter is 50-100 μm. The fine filter branch comprises a second branch pipe communicating with the main oil pipeline, wherein a third solenoid valve and a fine filter are sequentially provided on the second branch pipe, and the filtration accuracy of the fine filter is 5-20 μm. Both the first branch pipe and the second branch pipe are connected to the oil storage tank via the main oil pipeline; A control system includes a controller, a liquid level sensor arranged in the oil storage tank, and a flow rate sensor arranged on the main oil pipeline downstream of the filtration system. The liquid level sensor and the flow rate sensor are both electrically connected to the controller, and the first solenoid valve, the second solenoid valve, the third solenoid valve and the vacuum pump are also electrically connected to the controller respectively. The controller is configured to control the start and stop of the vacuum pump according to the detection signal of the liquid level sensor, and to adjust the power of the vacuum pump according to the detection signal of the flow rate sensor. When coarse filtration is required, the controller controls the first solenoid valve and the second solenoid valve to open and the third solenoid valve to close. When fine filtration is required, the controller controls the first solenoid valve and the third solenoid valve to open and the second solenoid valve to close.

2. The transformer oil extraction and efficient collection device according to claim 1, characterized in that: The oil extraction interface is connected to the oil extraction port of the transformer through a universal quick-connect valve group. The universal quick-connect valve group includes a metal conversion head, an elastic sealing sleeve, a strong magnetic ring and a threaded locking structure. The metal conversion head is provided with three specifications, namely, conversion heads suitable for the oil extraction ports of Φ10 mm, Φ16 mm, and Φ25 mm transformers. The elastic sealing sleeve is provided with two materials, namely, an oil-resistant rubber sleeve and a fluororubber sleeve. The magnetic force of the strong magnetic ring is not less than 50 N, and the pitch of the threaded locking structure is 1.5 mm. The strong magnetic ring is used to pre-fix the metal conversion head on the oil extraction port of the transformer, and the threaded locking structure is used to thread the metal conversion head to the oil extraction port of the transformer and perform secondary sealing.

3. The transformer oil extraction and efficient collection device according to claim 1, characterized in that: Also includes: A vacuum sampling bottle assembly includes a sampling bottle and a sampling needle connected in sequence. The capacity of the sampling bottle is 100 mL or 250 mL. The sampling bottle is a sealed bottle pre-evacuated to -80 kPa. The sampling needle is arranged at the bottle mouth of the sampling bottle. The bottle mouth is provided with an on-off valve for connecting the sampling needle. The sampling needle is connected to the sampling tube through a flange quick-release interface, and then connected to the sampling port of the oil storage tank. The flange quick-release interface is a DN15 PN1.6 bottle mouth flange. An O-ring is provided on the bottle mouth flange. The flange quick-release interface is connected to the sampling tube through a snap-fit ​​structure, and the leakage rate is not more than 0.1 mL / min.

4. The transformer oil extraction and efficient collection device according to claim 1, characterized in that: The inlet and outlet ends of the coarse filter and the fine filter are respectively provided with differential pressure sensors, which are electrically connected to the controller. A pre-filter is installed in series on the second branch pipe before the inlet of the fine filter, and the filtration accuracy of the pre-filter is 10-30 μm. The controller is preset with a pressure difference-flow rate correlation model, Q = Q 0× in, Q Indicates the real-time flow rate. Q 0 represents the initial flow rate, k Indicates the filter element clogging coefficient, Δ P Indicates the pressure difference, t Indicates the running time; If the coarse filter branch is currently in use, when it is detected k >5×10 -5 MPa -1 s -1 When , it automatically switches to the fine filter branch; If the fine filter branch is currently in use, when it is detected k >2.5×10 -5 MPa -1 s -1 When the alarm stops, 5. The transformer oil extraction and efficient collection device according to claim 1, characterized in that: The inlet and outlet ends of the coarse filter and the fine filter are respectively provided with pressure differential sensors, and the pressure differential sensors are electrically connected to the controller. The coarse filter and the fine filter are both provided with a backwash circuit, and the backwash circuit includes a third branch pipe connected to the outlet end of the coarse filter and a fourth branch pipe connected to the outlet end of the fine filter. A fourth solenoid valve and a fifth solenoid valve are respectively provided on the third branch pipe and the fourth branch pipe. The third branch pipe and the fourth branch pipe are both directly connected to the main oil pipeline upstream of the vacuum pump through the backwash main pipe. The third branch pipe and the fourth branch pipe are independently connected to the sewage tank through the seventh solenoid valve. An independent oil drainage pipeline is provided at the bottom of the sewage tank. A sixth solenoid valve is provided on the independent oil drainage pipeline. The controller is configured to perform the following operations in sequence when the flow rate sensor detects that the flow rate in the main oil pipeline drops by more than 20% and the pressure difference exceeds 0.05 MPa: closing the first solenoid valve, the second solenoid valve, and the third solenoid valve; Start the vacuum pump; Open the fourth solenoid valve or the fifth solenoid valve of the corresponding branch, and the seventh solenoid valve of the corresponding branch; Maintain the backwash state for 30-60 seconds, during which the vacuum pump power dynamically maintains the pressure of the backwash main pipe within the range of 0.1-0.15MPa; Close the fourth solenoid valve or the fifth solenoid valve, or the seventh solenoid valve; Open the sixth solenoid valve to discharge the dirty oil in the sewage tank.

6. The transformer oil efficient collection device according to claim 5, characterized in that: Maintain backwash status graded control: Phase 1: The controller reduces the vacuum pump power to 30-40% of the rated value and triggers the vibration system to backflush for 30 seconds. The vibration system includes a piezoelectric ceramic sheet mounted on the surface of the coarse filter and fine filter housings. The piezoelectric ceramic sheet is connected to a high-frequency power supply, which activates the piezoelectric ceramic sheet to generate 28 kHz ultrasonic vibration with an amplitude of 50 μm. The contact surface between the piezoelectric ceramic sheet and the filter housing is filled with thermal grease. A temperature sensor monitors the filter temperature in real time and shuts off the ultrasonic power supply when the temperature exceeds 80°C. If the pressure difference does not drop by 40% after the first stage, the second stage will begin; Phase 2: The controller increases the vacuum pump power to 40-50% of the rated value and simultaneously triggers the pulse gas system to backflush for 15 seconds. The pulse gas circuit system includes an air storage tank, a pulse solenoid valve and a pressure sensor arranged on the backwash main pipe. The air storage tank is pre-filled with nitrogen to 0.2-0.5 MPa. The controller opens / closes the pulse solenoid valve at a frequency of 1-3 Hz, so that the high-pressure nitrogen and oil are mixed to form a pulse jet, which impacts the interior of the filter element. Each pulse lasts 50-100 ms. The third stage: Shut down the pulse gas system, and the controller reduces the vacuum pump power to 30-40% of the rated value, and backwashes for 15 seconds.

7. The transformer oil extraction and efficient collection device according to claim 6, characterized in that: For the coarse filter, the pulse air pressure is set to 0.2-0.3 MPa and the frequency is 1-2 Hz; For the fine filter, the pulse air pressure is set to 0.3-0.5 MPa and the frequency is 2-3 Hz.

8. A method for extracting oil from a transformer, characterized in that: Based on the device according to any one of claims 1 to 3, the method comprises: Connect the transformer oil outlet and the oil outlet port through the universal quick-connect valve group, open the first solenoid valve and the vacuum pump, so that the transformer oil is sucked into the main oil pipeline through the oil outlet port to create a negative pressure environment; Select the coarse filtration or fine filtration mode. In the coarse filtration mode, the first and second solenoid valves are opened, and the third solenoid valve is closed. The oil flows into the oil storage tank through the coarse filter. In the fine filtration mode, the first and third solenoid valves are opened, and the second solenoid valve is closed. The oil flows into the oil storage tank through the fine filter. Start and stop the vacuum pump according to the liquid level signal of the oil tank, monitor the liquid level of the oil tank in real time, and when the liquid level reaches the upper limit H max Turn off the vacuum pump; The vacuum pump power is dynamically adjusted according to the flow rate signal of the main oil pipeline. When the real-time flow rate is less than 80% of the initial flow rate, the vacuum pump power is increased by 20%. When the real-time flow rate is greater than 120% of the initial flow rate, the vacuum pump power is reduced by 15%. The initial flow rate is the average flow rate within 10 minutes after the system first runs stably. Connect the sampling bottle that has been pre-evacuated to -80 kPa to the sampling port of the oil storage tank; Open the on-off valve and control the oil sample to be injected into the sampling bottle at a flow rate of 20-50 mL / min.

9. The transformer oil extraction method according to claim 8, characterized in that: The inlet and outlet ends of the coarse filter and the fine filter are respectively provided with differential pressure sensors, which are electrically connected to the controller. A pre-filter is installed in series on the second branch pipe before the inlet of the fine filter, and the filtration accuracy of the pre-filter is 10-30 μm. The controller is preset with a pressure difference-flow rate correlation model, Q = Q 0× in, Q Indicates the real-time flow rate. Q 0 represents the initial flow rate, k Indicates the filter element clogging coefficient, Δ P Indicates the pressure difference, t Indicates the running time; Calculate the filter element clogging coefficient in real time. k >5×10 -5 MPa -1 s -1 When k>2.5×10 -5 MPa -1 s -1 When the alarm stops, the machine will sound an audible and visual alarm.

10. The transformer oil extraction method according to claim 8, characterized in that: When the flow rate in the main oil pipeline drops by more than 20% and the pressure difference exceeds 0.05 MPa, the first, second and third solenoid valves are closed, the vacuum pump is started, the fourth or fifth solenoid valve of the corresponding branch, and the seventh solenoid valve of the corresponding branch are opened, and the backwash program is started. The backwash state is maintained for 30-60 seconds, and the vacuum pump power is dynamically maintained to maintain the backwash main pipe pressure at 0.1-0.15 MPa; Phase 1: The controller reduces the vacuum pump power to 30-40% of the rated value and triggers the vibration system to perform backwashing for 30 seconds. If the pressure difference does not drop by 40% after the first phase, the second phase begins. The second stage: The controller increases the vacuum pump power to 40-50% of the rated value and triggers the pulse gas system at the same time, backwashing for 15 seconds. For the coarse filter, the pulse gas pressure is set to 0.2-0.3 MPa, the frequency is 1-2 Hz, for the fine filter, the pulse gas pressure is set to 0.3-0.5 MPa, the frequency is 2-3 Hz, and the duration of each pulse is 50-100 ms. The third stage: the pulse gas system is turned off, the controller reduces the vacuum pump power to 30-40% of the rated value, and reverse flushes for 15 seconds; Close the fourth solenoid valve or the fifth solenoid valve, the seventh solenoid valve, and open the sixth solenoid valve to drain the dirty oil in the drain tank. During the oil discharge, nitrogen is introduced into the drain tank for purge at a purge flow rate of 10 L / min.

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