An automatic control method for vacuum oil injection

Abstract

The present invention relates to an automatic control method for vacuum oil injection. A temperature sensor is used to collect the temperature values of the oil in the oil tank and the vacuum oil filter, and a deformation sensor is used to collect the deformation amount value of the oil tank. The PLC control system receives and stores the temperature values and deformation amount values. The PLC control system controls the operation of the vacuum unit and the vacuum oil filter according to the temperature values, deformation amount values and technological process. The audible and visual alarm issues prompt information of early warning, alarm and dangerous deformation according to the temperature values and deformation amount values. The PLC control system displays in real time the temperature values, deformation amount values, operation states of the vacuum unit and the vacuum oil filter, technological process information and alarm information. The present invention realizes the automatic control of vacuum oil injection, reduces the labor time of operators, and weakens the potential safety hazards to the operators caused by climbing high for operation; the automatic data saving is convenient for query, and avoids the deviation that may be caused by manual data recording every hour.

Description

Technical Field

[0001] The invention belongs to the technical field of vacuum oil injection for transformers and reactors, and particularly relates to an automatic control method for vacuum oil injection. Background Art

[0002] At present, the technological processes such as vacuum pumping, vacuum oil injection, and hot oil circulation of transformers and reactors are all manually controlled operations. Each technological process is manually switched, and relevant data such as vacuum degree, oil injection speed, temperature of transformer oil, oil speed during hot oil circulation, and time of vacuum oil injection and hot oil circulation are manually recorded every hour. Special operators are required to monitor the operating states of the vacuum unit, vacuum oil filter, and the transformer or reactor body, and 24-hour continuous manual operation is required. Especially during night work, operators are prone to fatigue operation, data recording may be deviated, professional operators are required to manually calculate the body vacuum leakage rate during vacuum pumping, the deformation amount of the fuel tank during vacuum pumping is manually measured, valves are manually opened or closed at night, and working at heights is likely to pose potential safety hazards to personnel, and may also have an adverse impact on the product quality of transformers and reactors. Subsequently, it is not convenient to query and trace the data. Summary of the Invention

[0003] In view of the above technical problems, the invention provides an automatic control method for vacuum oil injection of transformers and reactors to replace the existing manual operation technological process. The technical solution of the invention to achieve the above purpose is as follows:

[0004] An automatic control method for vacuum oil injection uses temperature sensors to collect the temperature values of the oil in the fuel tank and the vacuum oil filter, uses deformation sensors to collect the deformation amount values of the fuel tank, and uses sensors to automatically collect information to replace manual data recording; the PLC control system receives and stores the temperature values and deformation amount values, and the data can be traced back. The PLC control system controls the operation of the vacuum unit and the vacuum oil filter according to the temperature values, deformation amount values, and technological processes, and uses the PLC control system to replace manual switching of each technological process; the audible and visual alarm issues warning, alarm, and dangerous deformation prompt information according to the temperature values and deformation amount values, and uses the audible and visual automatic alarm function to replace manual monitoring, improving the safety of production; the PLC control system displays the temperature values, deformation amount values, operating states of the vacuum unit and the vacuum oil filter, technological process information, and alarm information in real time, and uses the automatic display function to replace manual inspection, improving the production efficiency.

[0005] Advantages of the Invention

[0006] The present invention utilizes a PLC control system and a control program module to achieve automatic control of vacuum oil injection. After connecting the physical pipelines in advance, during the vacuum oil injection process, the leakage rate of the main body and the deformation amount of the oil tank are automatically measured, reducing the labor time of operators and weakening the potential safety hazards for operators climbing to work at heights; the data is automatically saved for convenient query, reducing the potential hazards of no valve action during the conversion of each operation process, avoiding the deviation that may be caused by manual data recording every hour, automatically alarming in case of abnormalities, and not requiring special personnel to monitor in real time, thus reducing the labor cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some specific embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings belonging to the protection scope of this application can also be obtained based on these drawings.

[0008] Figure 1 is the logic flow block diagram of the automatic control method of the embodiment of the present invention;

[0009] Figure 2 is the electrical principle schematic diagram of the automatic control method of the embodiment of the present invention;

[0010] In the figure, 1 - oil tank, 2 - vacuum oil filter, 3 - first temperature sensor power supply box, 4 - first temperature sensor, 5 - deformation sensor power supply box, 6 - deformation sensor, 7 - second temperature sensor power supply box, 8 - second temperature sensor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0012] As Figure 1 shown, it is the logic flow block diagram of the automatic control method of the embodiment of the present invention; As Figure 2As shown in the figure, it is the electrical schematic diagram of the automatic control method of the embodiment of the present invention. A vacuum oil injection automatic control method uses a temperature sensor to collect the temperature values of the oil in the oil tank and the vacuum oil filter, and uses a deformation sensor to collect the deformation amount value of the oil tank. The vacuum oil filter 2 is connected to the oil tank 1 through an oil injection pipeline. A number of first temperature sensors 4 and deformation sensors 6 are arranged around the oil tank 1. The first temperature sensor power supply box 3 supplies power to the first temperature sensors 4. The first temperature sensors 4 collect the temperature values of the oil in the oil tank 1. The deformation sensor power supply box 5 supplies power to the deformation sensors 6. The deformation sensors 6 collect the deformation amount values of the oil tank 1 during the vacuum pumping process. A second temperature sensor 8 is arranged at the outlet of the vacuum oil filter 2. The second temperature sensor power supply box 7 supplies power to the second temperature sensor 8. The second temperature sensor 8 collects the temperature values of the oil at the outlet of the vacuum oil filter 2. The first temperature sensors 4, the second temperature sensors 8 and the deformation sensors 6 are respectively connected to the PLC control system to realize data transmission.

[0013] The first temperature sensor 4 is adsorbed on the oil tank wall with a magnet and can be moved. It is installed at any position on the oil tank wall to detect the oil level of the transformer oil in the oil tank 1; the second temperature sensor 8 is installed and fixed at the pipe joint between the vacuum oil filter pipeline and the oil tank, fixed with bolts, and a sealing gasket is added to ensure the tightness of the connection.

[0014] In order to further improve the accuracy of temperature detection, in actual installation, a temperature sensor can be installed at each of the transformer oil inlet and outlet, connected to a fixed pipe joint, fastened with bolts, and connected in series between the vacuum oil filter pipeline and the main body oil inlet and outlet; a temperature sensor is installed on the oil tank wall in the long axis direction of the transformer, adsorbed on the tank wall with a magnet, installed at any position, and can be moved freely to detect the oil level.

[0015] The PLC control system receives and stores the temperature values and deformation values, and controls the operation of the vacuum unit and the vacuum oil filter according to the temperature values, deformation values and technological process. The PLC control system is installed in the control cabinet, and the control cabinet is fixed on a trolley with rollers. High-strength polyurethane casters are installed at the lower part of the trolley, which is convenient for movement and use. The flexible movement and layout of the PLC control system in the workshop are realized by using the trolley. The control cabinet is provided with interfaces for quick connection with the vacuum oil filter 2 and the vacuum unit, and all wiring uses quick-insert interfaces, which is convenient for the quick connection of equipment. At the same time, the control cabinet is provided with buttons such as start, stop, pause, and emergency stop to manually handle unexpected situations. Different hierarchical permissions are set for the PLC control system, including: programmable permission, operation permission and viewing permission, making the operation of the PLC control system safer and more convenient. Electric valves are arranged in the oil injection pipeline and the vacuum extraction pipeline, and the signal wires of the electric valves are connected to the PLC control system. All electric valves use special materials for transformers, reactors or materials suitable for the production of transformers and reactors. The on-off and opening degree of the electric valves are controlled by the PLC control system. The control cabinet is provided with a display screen, and the PLC control system displays information through the display screen. Through the PLC control system, technological processes such as vacuum extraction, vacuum leakage rate measurement, oil tank deformation measurement, vacuum oil injection, hot oil circulation, and temperature control are automatically controlled. The PLC control system automatically saves data and has the functions of exporting data and querying previous data.

[0016] The audible and visual alarm issues warning, alarm, and dangerous deformation prompt messages according to the temperature values and deformation values. The audible and visual alarm can convey different information with a variety of sounds and lights, and automatically prompt operation status information such as program end, warning, alarm, and dangerous deformation.

[0017] The PLC control system displays the temperature values, deformation values, operation status of the vacuum unit and the vacuum oil filter, technological process information, and alarm information in real time through the display screen.

[0018] An automatic control method for vacuum oil injection of the present invention involves entering the operation process programs and control data of all devices into the PLC control system before the equipment runs, including: controlling the technological processes of vacuum pumping, vacuum oil injection, and hot oil circulation, and importing process indexes such as the vacuum degree, vacuum time, leakage rate standard value, tank deformation amount standard value, oil injection speed, oil injection temperature limit value, hot oil circulation time, hot oil circulation flow rate, hot oil circulation oil temperature limit value, etc. of products with various voltage levels into the PLC control system. This step can be achieved by programming an automatic control program with PLC. Connect the pipelines of each device to the valves of the transformer and reactor bodies in advance. During the vacuum oil injection process after starting, the vacuum unit, vacuum oil filter, and tank deformation measurement system automatically switch according to the process time of products with various selected voltage levels. The PLC control system automatically controls in real time and displays the calculated vacuum leakage rate and the measured tank deformation amount value, automatically opens or closes the electric valves required for each technological process or the electric valves that are not needed at the end of the technological process, and automatically alarms and displays the cause of the failure when abnormalities are found; automatically records and saves data such as vacuum degree, vacuum time, vacuum leakage rate, tank deformation amount, oil injection speed, temperature of transformer oil, oil injection time, hot oil circulation time, hot oil circulation flow rate, alarm information, and cause of the failure. The display screen shows data such as process time selection, vacuum degree, vacuum time, vacuum leakage rate, tank deformation amount, type of transformer oil, oil injection speed, oil injection temperature, oil injection time, hot oil circulation flow rate, hot oil circulation time, alarm information, and cause of the failure for products with various voltage levels, and the alarm and technological process information can be retrieved and viewed.

[0019] An automatic control method for vacuum oil injection of the present invention also involves the following auxiliary process methods, including:

[0020] 1. Pre-operation inspection process method, including the following steps:

[0021] Step 1.1, check the good grounding, ensuring reliable grounding of the transformer, reactor bodies, and other supporting metal parts.

[0022] Step 1.2, check whether each unit such as the vacuum unit and vacuum oil filter is in good operation.

[0023] Step 1.3, select the models of the vacuum unit and vacuum oil filter, and select equipment with different capacities in the PLC control system according to products with different voltage levels.

[0024] Step 1.4, check whether the vacuum pipeline and oil injection pipeline are clean and in good condition.

[0025] Step 1.5, take an oil sample for detection before oil injection to ensure the correctness of the oil sample. The oil sample indexes of products with different voltage levels are different, and this data is imported into the PLC control system in advance (editing is only allowed for those with editing permissions).

[0026] Step 1.6: The display screen shows the above pre-operation requirements. After checking and ensuring they are correct, press the OK key, and then proceed to the next process flow.

[0027] 2. Process method for pipeline connection, including the following steps:

[0028] Step 2.1: After the general assembly is completed, close all the valves connecting the conservator to the tank body and seal them with covers.

[0029] Step 2.2: Connect the metal bellows to the DN150 butterfly valve on the upper part of the tank and open the butterfly valve.

[0030] Step 2.3: Connect the vacuum gauge probe to the DN80 or DN50 butterfly valve on the upper part of the tank and open the butterfly valve.

[0031] Step 2.4: Install a DN50 electric valve and a remotely transmissible thermometer at the end of the oil injection pipeline.

[0032] Step 2.5: Connect the oil injection pipeline to the DN80 or DN50 ball valve at the lower part of the tank and open the valve.

[0033] Step 2.6: Install at least 7 detection points for the tank deformation measurement device, import the information into the PLC control system in advance, set the deformation measurement frequency and time, and connect the signal line to the PLC control system.

[0034] Step 2.7: Install at least 4 detection points for the tank temperature measurement device. According to the product process requirements of different voltage levels and the requirements for the oil injection stop position, install at least 4 detection points in the long axis direction of the tank, set the temperature measurement frequency and time, and connect the signal line to the PLC control system.

[0035] Step 2.8: Equipment self-check. If normal, press the OK key to proceed to the next process flow; if abnormal, display the fault cause.

[0036] 3. Process method for vacuum oil injection, including the following steps:

[0037] Step 3.1: Select the corresponding vacuum oil injection program according to the voltage level and capacity in the PLC control system. The process requirements for the pre-injection vacuum degree and the holding time corresponding to different voltage levels and capacities are imported into the PLC control system in advance and executed according to the process requirements during operation.

[0038] Step 3.2: Enter the tank volume (or the weight of transformer oil V = oil injection volume / 0.89) and the tank wall thickness in the PLC control system.

[0039] Step 3.3: Set the oil injection speed on the vacuum oil filter according to the product process requirements of different voltage levels.

[0040] Step 3.4: Press the start key to start automatic operation. Automatically start the vacuum unit to start vacuum pumping. During the vacuum pumping process, the deformation detection device automatically measures the deformation of the oil tank. The maximum elastic deformation shall not exceed 2 times the wall thickness. Alarm setting: When the elastic deformation is close to 2 times the wall thickness (the specific value can be set by the operator), an audible and visual alarm will prompt the operator to pay attention. If the deformation of the oil tank exceeds the specified value, the PLC will immediately automatically shut down the vacuum unit to stop vacuum pumping. Audible and visual alarm (special audible and visual settings, the operator can intuitively judge the cause of the alarm).

[0041] Step 3.5: Automatically record the vacuum gauge reading every hour during the vacuum pumping process and form a record table.

[0042] Step 3.6: Automatically measure the leakage rate during the vacuum pumping process and compare it with the standard value. If it does not meet the standard, an alarm will be given to notify the operator to detect leaks.

[0043] Step 3.7: Start counting down after the vacuum degree reaches the process requirements. After the countdown ends, automatically open the lower oil injection electric valve, start the vacuum oil filter, and start oil injection.

[0044] Step 3.8: For process requirements such as vacuum degree and oil injection speed during the oil injection process, automatically match the corresponding oil injection speed and vacuum degree requirements according to different voltage levels and capacities; during the vacuum oil injection process, automatically monitor and record the oil temperature at the outlet of the vacuum oil filter and compare it with the process requirements in the PLC automatic control program. When there is an overrun, an audible and visual alarm will be given, and the cause will be displayed on the screen, and the alarm can be manually eliminated; during the vacuum oil injection process, automatically monitor and record the vacuum degree and compare it with the process requirements in the PLC automatic control program. When there is an overrun, an audible and visual alarm will be given, and the cause will be displayed on the screen, and the alarm can be manually eliminated.

[0045] Step 3.9: Stop oil injection. Different voltage levels correspond to different oil injection stop conditions. When the temperature of two or more detection points of the temperature sensor significantly rises to the set value (the operator can set it), the vacuum oil filter will be closed, the oil injection electric valve will be closed, and oil injection will stop.

[0046] 4. Process method of hot oil circulation. Set the hot oil circulation process flow according to different voltage levels and structures, including the following steps:

[0047] Step 4.1: If hot oil circulation is required for the elevated seat, install an electric valve before connecting the pipeline, which can be automatically opened in sequence to achieve separate circulation.

[0048] Step 4.2: Electric valves may not be installed at the inlets and outlets of the transformer and reactor bodies, and remote temperature gauges may be installed to receive and record the uploaded temperature data.

[0049] Step 4.3: Compile the corresponding control program according to the voltage level and structure, and automatically record the temperature and circulation time.

[0050] Step 4.4: The display shows parameters such as cycle time, process and oil injection temperature.

[0051] Step 4.5: Provide sound and light prompts at the manual operation time node, and display the operation content on the screen.

[0052] During and after the execution of each of the above process flows, the PLC control system automatically saves data and automatically exports data after the process flow is completed. If there is an abnormality, an automatic alarm will be issued, and there is no need for a dedicated person to monitor in real time, reducing labor costs.

[0053] Finally, it should be noted that the above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them, and the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any technician familiar with the technical field can modify the technical solutions recorded in the above embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be covered within the protection scope of the present invention.

Claims

1. An automatic control method for vacuum oil injection, characterized in that, a temperature sensor is used to collect the temperature values of the oil in the oil tank and the vacuum oil filter, a deformation sensor is used to collect the deformation amount value of the oil tank, the PLC control system receives and stores the temperature value and the deformation amount value, and the PLC control system controls the operation of the vacuum unit and the vacuum oil filter according to the temperature value, the deformation amount value and the technological process. The sound and light alarm issues prompt information of early warning, alarm and dangerous deformation according to the temperature value and the deformation amount value. The PLC control system displays the temperature value, the deformation amount value, the operation status of the vacuum unit and the vacuum oil filter, the technological process information and the alarm information in real time; The automatic control method for vacuum oil injection further includes a technological method for vacuum oil injection, including the following steps: Step 3.1: Select the corresponding vacuum oil injection program according to the voltage level and capacity in the PLC control system; Step 3.2: Enter the volume of the oil tank or the weight of the transformer oil and the wall thickness of the oil tank in the PLC control system; Step 3.3: Set the oil injection speed on the vacuum oil filter according to the technological requirements of products with different voltage levels; Step 3.4: Press the start key to start automatic operation. During the vacuum pumping process, the deformation detection device automatically measures the deformation amount of the oil tank, and the maximum elastic deformation shall not exceed 2 times the wall thickness; early warning setting, when the elastic deformation amount is 2 times the wall thickness, the sound and light alarm prompts the operator to pay attention; if the deformation amount of the oil tank exceeds the regulation, the PLC immediately automatically shuts down the vacuum unit to stop vacuum pumping, and the sound and light alarm; Step 3.5: Automatically record the vacuum gauge reading every hour during the vacuum pumping process and form a record table; Step 3.6: Automatically measure the leakage rate during the vacuum pumping process and compare it with the standard value. If it does not meet the standard, alarm and notify the operator to detect leaks; Step 3.7: Start counting down after the vacuum degree reaches the technological requirements. After the countdown ends, automatically open the lower oil injection electric valve and start the vacuum oil filter to start oil injection; Step 3.8: During the vacuum oil injection process, automatically monitor and record the oil temperature at the outlet of the vacuum oil filter and compare it with the technological requirements in the PLC automatic control program; automatically monitor and record the vacuum degree and compare it with the technological requirements in the PLC automatic control program. When there is an out-of-tolerance, the sound and light alarm, and the cause is displayed on the screen; Step 3.9: Stop oil injection, close the vacuum oil filter, and close the oil injection electric valve.

2. An automatic control method for vacuum oil injection according to claim 1, characterized in that, the vacuum oil filter is connected to the oil tank through an oil injection pipeline. A number of first temperature sensors and deformation sensors are arranged around the oil tank. The first temperature sensor power supply box supplies power to the first temperature sensors, the deformation sensor power supply box supplies power to the deformation sensors. A second temperature sensor is arranged at the outlet of the vacuum oil filter, and the second temperature sensor power supply box supplies power to the second temperature sensor. The first temperature sensor, the second temperature sensor and the deformation sensor are respectively connected to the PLC control system to realize data transmission.

3. An automatic control method for vacuum oil injection according to claim 2, characterized in that, The PLC control system is installed in the control cabinet, which is fixed on a trolley with rollers. High-strength polyurethane casters are installed at the lower part of the trolley. The control cabinet is provided with interfaces for quick connection to the vacuum oil filter and the vacuum unit. All wiring uses quick-insert interfaces. The control cabinet is provided with start, stop, pause, and emergency stop buttons, and a display screen.

4. A vacuum oil injection automatic control method according to claim 3, characterized in that, The PLC control system sets different hierarchical permissions, including: programmable permission, operation permission, and viewing permission; electric valves are arranged in the oil injection pipeline and the vacuum pumping pipeline, and the signal lines of the electric valves are connected to the PLC control system. All electric valves are made of special materials for transformers and reactors. The on-off and opening degree of the electric valves are controlled by the PLC control system; the PLC control system automatically saves data and has the functions of exporting data and querying previous data.

5. A vacuum oil injection automatic control method according to claim 1, characterized in that, Before the equipment runs, the operation process programs and control data of all equipment are input into the PLC control system in advance, including: the technological processes of controlling vacuum pumping, vacuum oil injection, and hot oil circulation, and the vacuum degree, vacuum time, leakage rate standard value, tank deformation amount standard value, oil injection speed, oil injection temperature limit value, hot oil circulation time, hot oil circulation flow rate, and hot oil circulation oil temperature limit value of products of various voltage levels. This step is implemented by programming an automatic control program with PLC.

6. A vacuum oil injection automatic control method according to claim 5, characterized in that, It also includes the following auxiliary process methods: pre-operation inspection process method, pipeline connection process method, and hot oil circulation process method.

7. A vacuum oil injection automatic control method according to claim 6, characterized in that, The pre-operation inspection process method includes the following steps: Step 1.1, check the good grounding, and ensure that the transformer, reactor body, and other supporting metal parts are reliably grounded; Step 1.2, check whether the vacuum unit and the vacuum oil filter are in good operation; Step 1.3, select the models of the vacuum unit and the vacuum oil filter, and select equipment with different capacities in the PLC control system according to products of different voltage levels; Step 1.4, check whether the vacuum pipeline and the oil injection pipeline are clean and intact; Step 1.5, take an oil sample for detection before oil injection to ensure that the oil sample is correct; Step 1.6, the display screen shows the pre-operation requirements. After checking correctly, press the OK key, and then enter the next technological process.

8. A vacuum oil injection automatic control method according to claim 6, characterized in that, The pipeline connection process method includes the following steps: Step 2.1, after the general assembly is completed, close all the valves connecting the conservator and the tank body, and seal them with a cover plate; Step 2.2, connect the metal bellows to the DN150 butterfly valve on the upper tank, and open the butterfly valve; Step 2.3, connect the vacuum gauge probe to the DN80 or DN50 butterfly valve on the upper part of the tank and open the butterfly valve; Step 2.4: Install a DN50 electric valve and a remotely transmissible thermometer at the end of the oil injection pipeline; Step 2.5: Connect the oil injection pipeline to the DN80 or DN50 ball valve at the lower part of the oil tank and open the valve; Step 2.6: Install at least 7 oil tank deformation measurement devices, import the information into the PLC control system in advance, set the deformation measurement frequency and time, and connect the signal lines to the PLC control system; Step 2.7: Install at least 4 oil tank temperature measurement devices, according to the product process requirements of different voltage levels and the requirements of the oil injection stop position, set the temperature measurement frequency and time, and connect the signal lines to the PLC control system; Step 2.8: Conduct equipment self-check. If normal, press the OK key to enter the next process flow. If abnormal, display the cause of the fault.

9. According to a vacuum oil injection automatic control method as claimed in claim 6, characterized in that for the process method of hot oil circulation, set the process flow of hot oil circulation according to different voltage levels and structures, including the following steps: Step 4.1: If hot oil circulation is required for the elevated seat, install an electric valve before connecting the pipeline and open it automatically in sequence to achieve independent circulation; Step 4.2: No electric valve is installed at the inlets and outlets of the transformer and reactor bodies, and remotely transmissible thermometers are installed to receive and record the uploaded temperature data; Step 4.3: Compile corresponding control programs according to the voltage level and structure, and automatically record the temperature and circulation time; Step 4.4: The circulation time, process and oil injection temperature are displayed on the display screen; Step 4.5: Give an audible and visual prompt at the manual operation time node and display the operation content on the screen.

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