Intelligent oil injection device and oil injection method for distribution transformer

Abstract

The invention relates to an intelligent oil injection device and method for a distribution transformer. The device comprises a box body, an oil storage tank, a heating tank, a vacuum pump and an oil injection head, a multi-stage filter plate capable of being slidably replaced is arranged in the oil storage tank, and circulating filtration of oil and real-time detection of oil quality are achieved in cooperation with a first sensor; oil is subjected to temperature control heating through the heating tank and then conveyed to the oil injection head of a double-layer structure through the oil supplementing pipe, an inner pipe is used for oil injection, an outer pipe is connected with the vacuum pipe for vacuumizing, and vacuumizing and oil injection integrated operation is achieved. A permanent magnet is embedded in the oil injection head flange and can be in butt joint with a transformer oil injection port through magnetic attraction, and the sealing performance is guaranteed through a sealing gasket; the third sensor monitors the oil temperature and the liquid level in the transformer in real time, the oil injection amount is accurately controlled in combination with a temperature compensation algorithm, and automatic shutdown is achieved. The intelligent oil injection device integrates the functions of oil filtering, heating, vacuum oil injection, intelligent monitoring and alarming, the intelligence, precision and safety of the oil injection process are remarkably improved, and the insulation performance and the service life of the transformer are effectively guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power equipment maintenance, and in particular to an intelligent power distribution transformer oil injection device and method. BACKGROUND

[0002] In the field of power equipment maintenance, as the core equipment of power transmission and distribution, the quality and injection process of the internal insulating oil of the power distribution transformer directly determine the insulation performance, heat dissipation efficiency and service life of the equipment, so the oil injection operation is a key link in the daily maintenance and overhaul of the transformer. However, the current traditional power distribution transformer oil injection device still has many technical shortcomings, which is difficult to meet the intelligent and efficient maintenance requirements: on the one hand, the traditional device lacks a multi-stage precise filtering mechanism, impurities and particles mixed in the insulating oil can easily enter the inside of the transformer during the oil injection process, which can damage the integrity of the insulation layer and increase the risk of short circuit, breakdown and other faults; on the other hand, no reliable oil temperature control module is provided, and the increased viscosity of the oil in low temperature environment will cause uneven oil injection flow rate and insufficient filling, affecting the stable operation of the power system. SUMMARY

[0003] In order to make up for the above shortcomings, the present application provides an intelligent power distribution transformer oil injection device and method, which aims to solve the problems of insufficient oil quality filtration and lack of oil temperature control during the traditional power distribution transformer oil injection process, and to realize the intelligent, precise, efficient and safe of the power distribution transformer oil injection process, to ensure the insulation performance and service life of the transformer, and to improve the efficiency of power equipment maintenance.

[0004] In order to achieve the above goal, the technical scheme adopted by the present application is as follows:

[0005] An intelligent power distribution transformer oil injection device, comprising a box body, an oil storage tank is installed inside the box body, a refueling pipe is installed on one side of the oil storage tank, the top end of the refueling pipe extends to the outside of the box body, an oil delivery pipe is installed on the other side of the oil storage tank, an oil delivery valve is installed on the oil delivery pipe, the other end of the oil delivery pipe is connected with a heating tank, a oil supplement pipe is installed on the other side of the heating tank, the outside of the oil supplement pipe is wrapped with thermal insulation cotton to prevent the temperature of the heated oil from dropping during the transportation process, a oil supplement valve and a oil supplement pump are installed on one end of the oil supplement pipe close to the heating tank, a vacuum pump is installed on the top end of the heating tank to extract the air inside the transformer and form a negative pressure environment to avoid the contact between the oil and the air during the oil injection process to generate bubbles which can reduce the insulation performance of the transformer and increase the risk of short circuit. A vacuum tube is installed on the air inlet of the vacuum pump, and the other end of the vacuum tube and the oil supplement pipe are connected with an oil injection head.

[0006] Preferably, the oil injection head comprises an outer tube, a flange is fixedly connected to the outer wall of the outer tube, a permanent magnet is fixedly connected inside the flange, a sealing gasket is installed on the outer wall of the outer tube and abuts against the flange, the oil injection head flange is attracted to the transformer oil injection port flange by the permanent magnet, the sealing gasket is compressed, and the sealing performance is enhanced. An inner tube is installed inside the outer tube, and a filter screen is installed between the outer tube and the inner tube to prevent oil from entering the vacuum pipeline. The oil supplementing pipe is connected to the inner tube, and the vacuum pipe is connected to the outer tube. Through the connection mode of double pipes in parallel, integrated operation of vacuumizing and oil injection is realized, frequent switching of pipelines is not required, and oil injection efficiency is greatly improved.

[0007] Preferably, a plurality of filter plates are slidably connected to the top end of the oil storage tank, the oil is filtered in multiple stages, a plastic handle is arranged at the top end of the filter plate, and the filter plate can be disassembled by pulling it out upward, and the new filter plate can be inserted along the sliding groove after replacement. A first sensor is installed on the oil delivery pipe to detect the quality of the filtered oil, a return oil pipe is fixedly connected to the oil delivery pipe, a return oil pump and a return oil valve are installed on the return oil pipe, and the other end of the return oil pipe is connected to the oil storage tank. When the first sensor detects that the oil quality is unqualified, the system automatically closes the oil delivery valve, simultaneously opens the return oil valve and the return oil pump, and draws the unqualified oil in the oil delivery pipe back into the oil storage tank for re-filtering, thereby avoiding waste of oil.

[0008] Preferably, a weighing scale is installed at the bottom end of the oil storage tank to detect the remaining oil quantity of the oil storage tank in real time. A second sensor is installed near the connection between the inner wall of the heating tank and the oil supplementing pipe to detect the temperature of the oil. When the oil temperature reaches the required temperature, the oil supplementing valve is opened to supplement oil. A third sensor is installed on the inner wall of the outer tube to detect the oil temperature and liquid level in the transformer. When the oil reaches the target height, the oil injection is stopped.

[0009] Preferably, a warning light is installed at the top end of the box to alarm in the case of device failure, insufficient oil storage, excessively high oil temperature in the transformer, or constant oil height during oil injection, thereby notifying the staff to troubleshoot. An integrated panel is installed on one side of the box and connected to all electrical equipment of the device to realize centralized control. A screen and buttons are installed on the integrated panel to monitor the working state of the device in real time and manually intervene through the buttons when necessary. Two repair doors are installed on the other side of the box, and a handle is installed on each repair door for manual maintenance. A plurality of universal wheels are installed at the bottom of the box to facilitate movement of the device at different work sites.

[0010] The oil injection method based on the above device comprises the following steps:

[0011] S1, oil injection and filtration: insulating oil is injected into the oil storage tank through the oil filling pipe, and the oil is physically filtered through multiple filter plates. The remaining life of the filter element is predicted based on pressure difference accumulation:

[0012]

[0013] When the filter needs to be replaced;

[0014] Parameter meaning: Inlet and outlet pressure difference; Instantaneous flow; Material attenuation coefficient and cycle aging weight; Oil circulation times; Filter dirt index; Maximum tolerance of filter;

[0015] S2, oil quality detection: the first sensor detects the filtered oil quality in real time, if it is unqualified, the oil pump is started to pump the oil back to the oil tank for re-filtering;

[0016] S3, oil heating: qualified oil enters the heating tank for heating, the second sensor monitors the oil temperature in real time, and stops heating when the target temperature is reached;

[0017] S4, vacuumizing: the oil injection head is close to the transformer oil injection port, the magnetic body in the flange is used to realize magnetic docking, the sealing gasket is pressed tightly, the vacuum pump is started, and the internal air of the transformer is extracted through the vacuum pipe to form a negative pressure environment;

[0018] S5, oil injection: in the vacuum environment, the oil supplement pump and valve are opened, the heated clean oil is injected into the transformer through the oil supplement pipe and the inner pipe of the oil injection head, and the oil injection flow is dynamically adjusted according to the real-time liquid level in the transformer:

[0019]

[0020] Wherein, : oil injection flow at time t; : initial flow at the beginning of oil injection; : flow regulation coefficient, value ; : actual liquid level at time t; : target liquid level;

[0021] S6, automatic shutdown: the third sensor monitors the liquid level in the transformer in real time, when the liquid level tends to the target value, the oil supplement pump and valve are automatically closed, and the oil injection operation is completed. Because the volume of oil changes with temperature, the liquid level may be high or low, so the actual liquid level needs to be corrected by the oil temperature data monitored by the third sensor:

[0022]

[0023] Oil temperature compensated liquid level; Original liquid level collected by the third sensor; Oil liquid volume expansion coefficient; Real-time oil temperature collected by the third sensor; Reference oil temperature.

[0024] Working principle: when using the intelligent power distribution transformer oil injection device, first, inject insulating oil into the oil storage tank through the oil injection pipe, the multiple filter plates in the oil storage tank will perform multi-stage filtration on the oil liquid, and the weighing scale at the bottom end will monitor the remaining oil quantity in the oil storage tank in real time; then, the oil liquid enters the oil delivery pipe, the first sensor on the oil delivery pipe detects the oil quality, if the oil quality is unqualified, the system automatically closes the oil delivery valve and opens the oil return valve and the oil return pump, and the unqualified oil liquid is pumped back to the oil storage tank through the oil return pipe for re-filtration, if the oil quality is qualified, the oil delivery valve is opened to allow the oil liquid to enter the heating tank; the second sensor in the heating tank monitors the oil temperature in real time, after the oil liquid is heated to the required temperature, the oil supplement pump and the oil supplement valve are started, and the vacuum pump extracts air inside the transformer through the annular cavity between the outer pipe and the inner pipe to form a negative pressure environment; the injection head is adsorbed on the transformer oil injection port through the permanent magnet in the flange, the sealing gasket enhances the sealing effect, the oil supplement pipe injects oil into the transformer through the inner pipe of the injection head, the filter screen between the outer pipe and the inner pipe can prevent the oil liquid from entering the vacuum pipe, and the third sensor on the inner wall of the outer pipe monitors the oil temperature and the liquid level in the transformer in real time, and the oil injection is stopped when the liquid level reaches the target height; during the whole process, the screen of the integrated panel displays the working state of the device in real time, the buttons can be used for manual intervention, if abnormal conditions such as device failure and insufficient oil storage occur, the warning light at the top of the box body will issue an alarm, the universal wheels at the bottom of the box body facilitate the movement of the device at different work sites, and the repair door on one side of the box body facilitates subsequent maintenance and repair.

[0025] The present application has the following beneficial effects:

[0026] 1. Ensure pure oil quality: the device filters the insulating oil through the multiple sliding filter plates at the top end of the oil storage tank, and cooperates with the first sensor on the oil delivery pipe to detect the oil quality in real time, when detecting that the oil quality is unqualified, the system can automatically close the oil delivery valve and open the oil return valve and the oil return pump, and the unqualified oil liquid is pumped back to the oil storage tank for re-filtration through the oil return pipe, solving the problem of insufficient filtration of traditional devices, effectively removing impurities and particles in the oil, and significantly reducing the probability of device failure such as short circuit and breakdown.

[0027] 2. Adjustable oil temperature: the device is equipped with a heating tank and a second sensor, which can heat the oil liquid to the required temperature, and the outer side of the oil supplement pipe is wrapped with thermal insulation cotton to prevent the temperature of the oil liquid from dropping during transportation, effectively solving the problem of uneven oil injection flow rate and insufficient filling caused by the increase of oil viscosity in low temperature environment.

[0028] 3. Improve efficiency: through the double-pipe parallel structure of inner pipe oil injection and outer pipe vacuum extraction, integrated vacuum extraction and oil injection operation is realized, without frequent switching of pipelines, greatly improving the oil injection efficiency.

[0029] 4. Realize intelligent monitoring control: the weighing meter at the bottom of the oil storage tank can monitor the remaining oil in real time, the third sensor in the oil injection head can detect the oil temperature and liquid level in the transformer in real time, the screen of the integrated panel can display the working state of the device in real time, the button is convenient for manual intervention, if the device fails, the oil storage is insufficient, the oil temperature is abnormal, etc., the warning light at the top of the box can alarm in time, realize the intelligent monitoring of the oil injection process, reduce the manual value pressure, and improve the operation safety. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A perspective view of an intelligent power distribution transformer oil injection device and oil injection method is proposed.

[0031] Figure 2 A rear view of an intelligent power distribution transformer oil injection device and oil injection method is proposed.

[0032] Figure 3 A side view structure diagram of an intelligent power distribution transformer oil injection device and oil injection method is proposed.

[0033] Figure 4 A perspective view of an intelligent power distribution transformer oil injection device and oil injection method is proposed.

[0034] Figure 5 A cross-sectional view of an oil storage tank of an intelligent power distribution transformer oil injection device and oil injection method is proposed.

[0035] Figure 6 A cross-sectional view of a heating tank of an intelligent power distribution transformer oil injection device and oil injection method is proposed.

[0036] Figure 7 A cross-sectional view of an oil injection head of an intelligent power distribution transformer oil injection device and oil injection method is proposed.

[0037] Legend: 1, button; 2, universal wheel; 3, box; 4, integrated panel; 5, screen; 6, warning light; 7, vacuum pipe; 8, oil supplement pipe; 9, oil injection head; 10, repair door; 11, handle; 12, oil filling pipe; 13, oil storage tank; 14, weighing meter; 15, filter plate; 16, oil delivery pipe; 17, first sensor; 18, oil return pipe; 19, oil return pump; 20, oil return valve; 21, oil delivery valve; 22, heating tank; 23, vacuum pump; 24, oil supplement valve; 25, oil supplement pump; 26, second sensor; 27, flange; 28, permanent magnet; 29, gasket; 30, inner tube; 31, filter screen; 32, third sensor; 33, outer tube. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] like Figures 1 to 7 As shown, an intelligent distribution transformer oil injection device mainly includes a housing 3, inside which is an oil storage tank 13. Multiple slidable and detachable filter plates 15 are installed on the top for multi-stage physical filtration of the injected insulating oil. A weighing scale 14 is installed at the bottom of the oil storage tank 13 to monitor the oil level in real time and provide feedback to the screen 5 on the integrated panel 4. One side of the oil storage tank 13 is connected to a refueling pipe 12 for adding new oil; the other side is connected to a heating tank 22 via an oil delivery pipe 16. The oil delivery pipe 16 is equipped with an oil delivery valve 21 and a first sensor 17 for controlling the oil flow and detecting the quality of the filtered oil. When the first sensor 17 detects excessive impurities, the system automatically closes the oil delivery valve 21 and simultaneously opens the return oil valve 20 and the return oil pump 19, pumping the substandard oil back to the oil storage tank 13 via the return oil pipe 18 for further filtration, thus achieving circulation and purification.

[0040] After the oil enters the heating tank 22, it is heated by the built-in heating element. The second sensor 26 monitors the oil temperature in real time and transmits the data to the control system to ensure that the oil reaches the appropriate injection temperature before entering the next stage. A vacuum pump 23 is installed on the top of the heating tank 22, and its suction port is connected to the outer pipe 33 of the oil injection head 9 through the vacuum tube 7. The other side of the heating tank 22 is connected to the oil replenishment pipe 8, which is wrapped with insulation cotton to reduce heat loss. It is equipped with an oil replenishment pump 25 and an oil replenishment valve 24 to deliver the heated oil to the transformer.

[0041] The oil filling head 9 adopts a double-layer structure design, including an outer tube 33 and an inner tube 30. The outer tube 33 is connected to the vacuum tube 7 to extract air from inside the transformer and create a negative pressure environment to prevent air bubbles from forming during the oil filling process. The inner tube 30 is connected to the oil replenishment pipe 8 to inject insulating oil into the transformer. A filter screen 31 is installed between the outer tube 33 and the inner tube 30 to prevent oil from accidentally entering the vacuum system. The outer wall of the oil filling head 9 has a flange 27 with an embedded permanent magnet 28, which can be attracted to the transformer oil filling port flange and achieve a fast and reliable sealing connection with the sealing gasket 29. The third sensor 32 is installed on the inner wall of the outer tube 33 to monitor the oil temperature and liquid level inside the transformer in real time. When the liquid level reaches the preset value, the oil filling will automatically stop.

[0042] The whole device is centrally controlled by the integrated panel 4, and the screen 5 displays the parameters such as oil quantity, oil temperature, liquid level, valve state, etc. in real time. The operator can manually intervene through the button 1. When there are faults such as insufficient oil storage, abnormal oil quality, temperature overrun or oil injection stagnation, the warning light 6 automatically flashes to alarm. The bottom of the box body 3 is provided with universal wheels 2 for easy movement operation; the side is provided with two repair doors 10 with handles 11 for convenient maintenance and repair of internal elements.

[0043] Oil injection method:

[0044] 1: Through the oil injection pipe 12, insulating oil is injected into the oil storage tank 13, and the oil liquid is physically filtered through the multi-stage filter plate 15. The residual life of the filter element is predicted based on the differential pressure accumulation:

[0045]

[0046] When , it is determined that the filter element needs to be replaced;

[0047] Parameter meaning: Inlet and outlet port differential pressure; Instantaneous flow rate; Material attenuation coefficient and cycle aging weight; Oil liquid cycle number; Filter element dirtiness index; Maximum tolerance value of filter element;

[0048] 2: The first sensor 17 detects the filtered oil quality in real time. If it is unqualified, the oil return pump 19 is started to pump the oil back to the oil storage tank 13 for re-filtering;

[0049] 3: The qualified oil liquid enters the heating tank 22 for heating, and the second sensor 26 monitors the oil temperature in real time. When the target temperature is reached, the heating is stopped;

[0050] 4: The oil injection head 9 is close to the transformer oil injection port. The permanent magnet 28 in the flange 27 is used to realize magnetic attraction docking. The sealing gasket 29 is compressed and sealed. The vacuum pump 23 is started. The transformer internal air is extracted through the vacuum pipe 7 to form a negative pressure environment;

[0051] 5: In the vacuum environment, the oil supplement pump 25 and the oil supplement valve 24 are opened. The clean oil after heating is injected into the transformer through the oil supplement pipe 8 and the inner pipe 30 of the oil injection head. According to the real-time liquid level in the transformer, the oil injection flow rate is dynamically adjusted:

[0052]

[0053] Among them, : oil injection flow rate at time t; : initial flow rate at the beginning of oil injection; : flow rate adjustment coefficient, value ; : actual liquid level at time t; : target liquid level;

[0054] 6: The third sensor 32 monitors the liquid level inside the transformer in real time. When the liquid level tends to the target value, the oil filling pump and valve are automatically closed, and the oil filling operation is completed. Since the volume of oil changes with temperature, it may cause the liquid level to be falsely high or low. Therefore, the actual liquid level needs to be corrected by the oil temperature data monitored by the third sensor 32:

[0055]

[0056] Liquid level after oil temperature compensation; Original liquid level collected by the third sensor; Volume expansion coefficient of oil; Real-time oil temperature collected by the third sensor; Reference oil temperature.

[0057] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made shall be included in the protection scope of the present application.

Claims

1. An intelligent distribution transformer oil injection device, comprising a housing (3), characterized in that: The housing (3) is equipped with an oil storage tank (13). An oil filling pipe (12) is installed on one side of the oil storage tank (13), and an oil delivery pipe (16) is installed on the other side of the oil storage tank (13). An oil delivery valve (21) is installed on the oil delivery pipe (16), and the other end of the oil delivery pipe (16) is connected to the heating tank (22). An oil replenishment pipe (8) is installed on the other side of the heating tank (22). An oil replenishment valve (24) and an oil replenishment pump (25) are installed on the oil replenishment pipe (8) near the heating tank (22). A vacuum pump (23) is installed at the top of the heating tank (22). A vacuum tube (7) is installed at the suction port of the vacuum pump (23). The other ends of the vacuum tube (7) and the oil replenishment pipe (8) are both connected to the oil injection head (9).

2. The intelligent distribution transformer oil injection device according to claim 1, characterized in that: The oil injection head (9) includes an outer tube (33), a flange (27) is fixedly connected to the outer wall of the outer tube (33), a permanent magnet (28) is fixedly connected inside the flange (27), a sealing gasket (29) is installed on the outer wall of the outer tube (33), the sealing gasket (29) is tightly attached to the flange (27), an inner tube (30) is installed inside the outer tube (33), a filter screen (31) is installed in the annular cavity between the outer tube (33) and the inner tube (30), the oil replenishment pipe (8) is connected to the inner tube (30), and the vacuum pipe (7) is connected to the annular cavity between the outer tube (33) and the inner tube (30).

3. The intelligent distribution transformer oil injection device according to claim 1, characterized in that: Multiple filter plates (15) are slidably connected to the top of the oil storage tank (13).

4. The intelligent distribution transformer oil injection device according to claim 1, characterized in that: The first sensor (17) is installed on the oil pipeline (16). The first sensor (17) is an integrated sensor of moisture and dissolved gas. The oil pipeline (16) is fixedly connected to the return oil pipeline (18). The return oil pipeline (18) is equipped with a return oil pump (19) and a return oil valve (20). The other end of the return oil pipeline (18) is connected to the oil storage tank (13).

5. The intelligent distribution transformer oil injection device according to claim 1, characterized in that: A weighing scale (14) is installed at the bottom of the oil storage tank (13).

6. The intelligent distribution transformer oil injection device according to claim 1, characterized in that: A second sensor (26) is installed near the connection between the inner wall of the heating tank (22) and the oil supply pipe (8). The second sensor (26) is a temperature sensor.

7. The intelligent distribution transformer oil injection device according to claim 2, characterized in that: The inner wall of the outer tube (33) is equipped with a third sensor (32), which is an infrared sensor.

8. The intelligent distribution transformer oil injection device according to claim 1, characterized in that: A warning light (6) is installed on the top of the box (3), and an integrated panel (4) is installed on one side of the box (3). A screen (5) and a button (1) are installed on the integrated panel (4).

9. The intelligent distribution transformer oil injection device according to claim 1, characterized in that: Two repair doors (10) are installed on the other side of the box (3), each of the repair doors (10) is equipped with a handle (11), and multiple casters (2) are installed at the bottom of the box (3).

10. An oil injection method for the intelligent distribution transformer oil injection device as described in claims 1-9, characterized in that: Includes the following steps: S1. Oil Injection and Filtration: Insulating oil is injected into the oil storage tank (13) through the oil filling pipe (12). The oil undergoes physical filtration through multi-stage filter plates (15). The remaining life of the filter element is predicted based on the cumulative pressure difference. when When the filter needs to be replaced, it is determined that the filter element needs to be replaced. Parameter meaning: Pressure difference between inlet and outlet; Instantaneous flow rate; Material degradation coefficient and cyclic aging weight; Number of oil circulation cycles; Filter element dirt index; Maximum tolerance of filter element; S2, Oil quality detection: The first sensor (17) detects the quality of the filtered oil in real time. If it is not qualified, the return oil pump (19) is started to pump the oil back to the storage tank (13) for re-filtration. S3, Oil heating: Qualified oil enters the heating tank (22) for heating. The second sensor (26) monitors the oil temperature in real time. Heating stops after the target temperature is reached. S4. Vacuuming: Place the oil filling head (9) close to the transformer oil filling port, use the permanent magnet (28) inside the flange (27) to achieve magnetic attraction docking, press the sealing gasket (29) to seal, start the vacuum pump (23), and extract the air inside the transformer through the vacuum tube (7) to form a negative pressure environment; S5. Oil Injection: Under vacuum conditions, turn on the oil replenishment pump (25) and the oil replenishment valve (24). The heated clean oil is injected into the transformer through the oil replenishment pipe (8) and the inner pipe (30) of the oil injection head. The oil injection flow rate is dynamically adjusted according to the real-time liquid level in the transformer. in, : Oil injection flow rate at time t; Initial flow rate during the initial stage of oil injection; Flow regulation coefficient, value ; : Actual liquid level at time t; Target liquid level; S6. Automatic shutdown: The third sensor (32) monitors the internal liquid level of the transformer in real time. When the liquid level approaches the target value, the oil pump and valve are automatically shut off to complete the oil injection operation. Since the oil volume changes with temperature, the liquid level may be falsely high or low. The actual liquid level needs to be corrected by the oil temperature data monitored by the third sensor (32). Oil level after temperature compensation; The raw liquid level was collected by the third sensor; Oil volume expansion coefficient; Real-time oil temperature collected by the third sensor; Reference oil temperature.

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