System for measuring and calculating amount of residual mineral oil in transformer winding

Abstract

A system for measuring and calculating the amount of the residual mineral oil in a transformer winding, said system comprising: an oil tank (1), a transformer winding (2), a sampling bottle (3), an oil extraction channel (4), a power supply module (5), a control module (6), and a superordinate computer; the power supply module (5) is used for applying a rated current to the transformer winding (2); the control module (6) is used for controlling the opening of the oil extraction channel (4) after each preset duration, so that the sampling bottle (3) extracts a preset volume of mixed insulating liquid from the oil tank (1); and the superordinate computer is used for performing a viscosity test on the mixed insulating liquid sampled each time in the sampling bottle (3), so as to obtain a viscosity value of the mixed insulating liquid extracted each time; on the basis of the viscosity value of the mixed insulating liquid extracted each time, calculating a mineral oil amount preselection value in the oil tank during each sampling; and from among all the mineral oil amount preselection values, determining a mineral oil amount final value. By measuring a viscosity value during each sampling, then calculating mineral oil amount preselection values, and finally selecting a final value from the mineral oil amount preselection values, the analysis of the mineral oil diffusion process, and the measurement and calculation of the residual amount are completed.

Description

A transformer winding residual mineral oil content measurement system TECHNICAL FIELD

[0001] The present application relates to the field of transformer oil refilling, in particular to a transformer winding residual mineral oil content measurement system. BACKGROUND

[0002] In order to accelerate the construction of new power systems, natural esters are increasingly used to replace old mineral oil in service transformers. Compared with traditional mineral oil, natural esters not only have a high ignition point and are easy to degrade, but also can significantly improve the heat resistance of oil-paper insulation systems when used with insulation paper.

[0003] However, due to the limitations of the refilling process, existing replacement technologies cannot completely remove the residual mineral oil in the refilled transformer, so the actual mixed insulation liquid in the refilled transformer tank is a mixture of natural esters and a small amount of mineral oil. This makes the ignition point of the mixed insulation liquid significantly lower than that of natural esters, which may no longer meet the ignition point limit of K-class non-flammable liquid, and the high ignition point advantage of replacing mineral oil with natural esters is lost. In order to improve the fire safety level of natural ester refilled transformers, how to evaluate the mineral oil content in the mixed insulation liquid in the refilled transformer and study the diffusion process of mineral oil is a problem that needs to be solved. SUMMARY

[0004] The present application provides a transformer winding residual mineral oil content measurement system to study the diffusion process of mineral oil in the mixed insulation liquid in the natural ester refilled transformer and obtain the mineral oil content in the mixed insulation liquid when the diffusion reaches equilibrium.

[0005] To solve the above technical problems, the present application provides a transformer winding residual mineral oil content measurement system, which comprises an oil tank, a transformer winding, a sampling bottle, an oil extraction channel, a power supply module, a control module and an upper computer. The oil tank is refilled with natural esters after the mineral oil is discharged. The transformer winding is arranged inside the oil tank. The sampling bottle is connected to the oil tank through the oil extraction channel. The power supply module is connected to both ends of the transformer winding through wires.

[0006] The power supply module is used to apply rated current to the transformer winding.

[0007] The control module is used to control the oil extraction channel to open every preset time interval to make the sampling bottle extract a preset volume of mixed insulation liquid from the oil tank.

[0008] The upper computer is used for testing the viscosity of the mixed insulating liquid in each sampling of the sampling bottle to obtain the viscosity value of the mixed insulating liquid in each sampling; the preselected value of the mineral oil content in the oil tank in each sampling is calculated according to the viscosity value of the mixed insulating liquid in each sampling; and the final selected value of the mineral oil content is determined according to all the preselected values of the mineral oil content.

[0009] As a preferred solution, the transformer winding comprises a core and copper wires wrapped with insulating paper; the core is made of silicon steel sheets stacked; and the copper wires are uniformly wound on the surface of the core.

[0010] As a preferred solution, the oil tank transformer winding is grounded.

[0011] As a preferred solution, the transformer winding residual mineral oil content measuring system further comprises a natural ester oil tank and an oil inlet channel; the natural ester oil tank is connected to the oil tank through the oil inlet channel.

[0012] The control module is further used for controlling the oil inlet channel to be opened so that the natural ester in the natural ester oil tank enters the oil tank.

[0013] As a preferred solution, the transformer winding residual mineral oil content measuring system further comprises a temperature sensor; the temperature sensor device is installed at the upper end of the inner wall of the oil tank.

[0014] The temperature sensor is used for monitoring the temperature at the upper end in the tank body in real time and triggering power-off when the temperature exceeds a preset temperature value, so that the power supply module stops power supply.

[0015] As a preferred solution, the oil tank comprises a tank body and a sealing cover.

[0016] As a preferred solution, the viscosity test on the mixed insulating liquid in this sampling to obtain the viscosity value of the mixed insulating liquid in this sampling comprises:

[0017] The mixed insulating liquid in this sampling is tested for viscosity for several times to obtain several test results;

[0018] The average value of all the test results is taken as the viscosity value of the mixed insulating liquid in this sampling.

[0019] As a preferred solution, the determination of the final selected value of the mineral oil content according to all the preselected values of the mineral oil content comprises:

[0020] The change relationship of the mineral oil content with the sampling time is obtained according to all the preselected values of the mineral oil content;

[0021] The preselected value of the mineral oil content is determined when the mineral oil content value tends to be stable according to the change relationship of the mineral oil content with the sampling time.

[0022] The maximum mineral oil pre-selected value when the mineral oil content value tends to be stable is taken as the final selected value of the mineral oil content.

[0023] Compared with the prior art, the embodiment of the present application has the following beneficial effects:

[0024] The present application comprises an oil tank, a transformer winding, a sampling bottle, an oil taking channel, a power supply module, a control module and an upper computer; the oil tank is refilled with natural ester after discharging mineral oil; the transformer winding is arranged inside the oil tank; the sampling bottle is connected with the oil tank through the oil taking channel; the power supply module is connected with both ends of the transformer winding through wires; the power supply module is used for applying rated current to the transformer winding; the control module is used for controlling the oil taking channel to open after every preset time interval, so that the sampling bottle takes out a preset volume of mixed insulation liquid from the oil tank; the upper computer is used for testing the viscosity of the mixed insulation liquid taken out each time, so as to obtain the viscosity value of the mixed insulation liquid taken out each time; the mineral oil content pre-selected value in the oil tank at each sampling time is calculated according to the viscosity value of the mixed insulation liquid taken out each time; and the final selected value of the mineral oil content is determined according to all the mineral oil content pre-selected values. The present application completes the measurement of the mineral oil content by taking out the mixed insulation liquid multiple times during the process of electrifying the transformer winding, measuring the viscosity value of each sampling and calculating the mineral oil content pre-selected value, and finally selecting the final value from the several mineral oil content pre-selected values. BRIEF DESCRIPTION OF DRAWINGS

[0025] Fig. 1 is a structural schematic diagram of a transformer winding residual mineral oil content measurement system provided by an embodiment of the present application;

[0026] In the drawings, the reference signs of the drawings are as follows: oil tank 1, transformer winding 2, sampling bottle 3, oil taking channel 4, power supply module 5 and control module 6. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present application more clear, the technical scheme in the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the description and claims of this application as well as the above abstract are intended to cover all alternatives, modifications, and equivalents thereof in accordance with the scope of the application as defined by the claims. Throughout this application the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. By "consisting of" is meant including, and limited to, whatever follows the phrase "consisting of." When the phrase "consists of" appears in the body of the detailed description, the use of such phrase is not intended to invoke the interpretation defined by 35 U.S.C. § 112, paragraph 6. By "consisting essentially of" is meant including the elements listed after the phrase, and limited to other elements of: nonessential to the scope of the application claimed. By "comprising" is meant including, but not limited to, whatever follows the term "comprising." By "method comprising" is meant including a process, technique, method, or procedure, but not limited to, whatever follows the term "comprising."

[0029] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to a single alternative implementation. It is explicitly contemplated that embodiments described herein can be combined with each other in their individual aspects.

[0030] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without any creative effort fall within the protection scope of the present application.

[0031] Embodiment one

[0032] Please refer to Fig. 1, which is a structural schematic diagram of a transformer winding residual mineral oil content measuring system provided by an embodiment of the present application, comprising: an oil tank 1, a transformer winding 2, a sampling bottle 3, an oil taking channel 4, a power supply module 5, a control module 6 and an upper computer (not shown in Fig. 1); the oil tank 1 is refilled with natural ester after discharging mineral oil; the transformer winding is arranged inside the oil tank 1; the sampling bottle 3 is connected with the oil tank 1 through the oil taking channel 4; the power supply module 5 is connected with both ends of the transformer winding 2 through wires;

[0033] The power supply module 5 is used for applying rated current to the transformer winding 2.

[0034] The control module 6 is used for controlling the oil taking channel 4 to open after every preset time length, so that the sampling bottle 3 takes out a preset volume of mixed insulation liquid from the oil tank 1.

[0035] The upper computer is used for performing viscosity test on the mixed insulation liquid sampled each time in the sampling bottle 3, obtaining the viscosity value of the mixed insulation liquid taken out each time; calculating a preselected value of the mineral oil content in the oil tank at each sampling time according to the viscosity value of the mixed insulation liquid taken out each time; and determining a final selected value of the mineral oil content according to all the preselected values of the mineral oil content.

[0036] It should be noted that, since the proportion of mineral oil has a linear relationship with the viscosity of the mixed insulation liquid, the content of mineral oil in the mixed insulation liquid can be calculated by measuring the viscosity of the mixed insulation liquid. The content of mineral oil in the mixed insulation liquid is determined by evaluating the diffusion process of mineral oil from the transformer winding 2 to the insulation oil.

[0037] The transformer winding 2 and the oil tank 1 used in the transformer winding residual mineral oil content calculation system constitute a simple oil-immersed transformer winding 2 scale model. By calculating the content of mineral oil in the mixed insulation liquid in the transformer winding 2 scale model, the content of mineral oil in the original scale transformer winding 2 can be inferred. The use of the scale model makes the calculation process more convenient and reduces resource consumption.

[0038] In this embodiment, the transformer oil originally loaded in the oil tank 1 is mineral oil. Later, due to technical improvement, natural ester is used to replace mineral oil. The transformer winding is arranged inside the oil tank 1, and the liquid level of the natural ester in the oil tank 1 completely covers the transformer winding 2. The sampling bottle 3 is connected to the oil tank 1 through the oil taking channel 4. When the oil taking channel 4 is opened, the liquid in the oil tank 1 is taken out through the oil taking channel 4 to the sampling bottle 3. The power supply module 5 is connected to both ends of the transformer winding 2 through wires.

[0039] The power supply module 5 is a large current generator used to apply rated current to the transformer winding 2. It should be noted that when the power supply module 5 is turned on, it is necessary to ensure that there are as few bubbles as possible in the oil tank 1.

[0040] While the power supply module 5 applies rated current to the transformer winding 2, the control module 6 controls the oil taking channel 4 to open every pre-set time interval to make the sampling bottle 3 take out a pre-set volume of mixed insulation liquid from the mailbox.

[0041] After each sampling, the host computer tests the viscosity of the mixed insulation liquid sampled each time in the sampling bottle 3 to obtain the viscosity value of the mixed insulation liquid taken out each time; then according to the linear relationship between the viscosity value and the proportion of mineral oil, the content of mineral oil at each sampling is calculated, and the calculated content of mineral oil at this time is a pre-selected value; finally, according to all the pre-selected values of the content of mineral oil calculated, the final selected value of the content of mineral oil is determined. The final selected value of the content of mineral oil is used as the content of mineral oil of the original scale transformer winding 2.

[0042] In a preferred embodiment, the control module 6 opens the oil taking channel 4 once every 8 hours.

[0043] In a preferred embodiment, the sampling bottle 3 takes out 30 milliliters of mixed insulation liquid from the oil tank 1 each time.

[0044] In a preferred embodiment, the transformer winding 2 comprises a core made of silicon steel sheet stack and copper wire wrapped with insulating paper and uniformly wound on the surface of the core.

[0045] In the embodiment, the transformer winding 2 comprises a core made of silicon steel sheet stack and copper wire wrapped with insulating paper and uniformly wound on the surface of the core.

[0046] In a preferred embodiment, the transformer winding 2 is grounded.

[0047] In the embodiment, the grounding of the transformer winding 2 can reduce the risk of electric shock.

[0048] In a preferred embodiment, the bottom of the oil tank 1 is made of metal; the core of the transformer winding 2 is connected to the bottom of the oil tank 1; and the bottom of the oil tank 1 is grounded.

[0049] In a preferred embodiment, the transformer winding residual mineral oil content measurement system further comprises a natural ester oil tank and an oil inlet channel; the natural ester oil tank is connected to the oil tank 1 through the oil inlet channel.

[0050] The control module 6 is further configured to control the oil inlet channel to open, so that the natural ester in the natural ester oil tank enters the oil tank.

[0051] In the embodiment, the natural ester oil tank is connected to the oil tank 1 through the oil inlet channel. After the oil in the oil tank 1 is discharged, the control module 6 controls the oil inlet channel to open, so that the natural ester in the natural ester oil tank enters the oil tank and passes through the transformer winding 2.

[0052] In a preferred embodiment, the transformer winding residual mineral oil content measurement system further comprises a temperature sensor; the temperature sensor is installed at the upper end of the inner wall of the oil tank 1.

[0053] The temperature sensor is configured to monitor the temperature at the upper end of the tank in real time and trigger power-off when the temperature exceeds a preset temperature value, so that the power supply module 5 stops supplying power.

[0054] In the embodiment, the temperature sensor is installed at the upper end of the inner wall of the oil tank 1, which can monitor the temperature of the insulating oil in the oil tank 1 and the temperature of the upper end of the transformer winding in real time. If the local temperature is too high, power-off is triggered to make the power supply module 5 stop applying current immediately. This prevents the system from being damaged by the high temperature of the winding hot spot, and helps to ensure the safety of the system.

[0055] In a preferred embodiment, the oil tank 1 comprises a tank body and a sealing cover.

[0056] In the embodiment, the sealed cover on the top of the oil tank 1 is opened, and the transformer winding can be replaced, so that the transformer winding can be reused multiple times.

[0057] In a preferred embodiment, the viscosity of the mixed insulation liquid taken out this time is tested to obtain the viscosity value of the mixed insulation liquid taken out this time, including:

[0058] The mixed insulation liquid taken out this time is tested for several times to obtain several test results.

[0059] The average value of all test results is taken as the viscosity value of the mixed insulation liquid taken out this time.

[0060] In the embodiment, the mixed insulation liquid taken out this time is tested for several times, and the average value of the several viscosity tests is taken as the viscosity value of the mixed insulation liquid taken out this time.

[0061] In a preferred embodiment, the final selected value of the mineral oil content is determined according to all the preselected values of the mineral oil content, including:

[0062] According to all the preselected values of the mineral oil content, the relationship between the mineral oil content and the sampling time is obtained.

[0063] According to the relationship between the mineral oil content and the sampling time, the preselected value of the mineral oil content when the mineral oil content value tends to be stable is determined.

[0064] The largest preselected value of the mineral oil content when the mineral oil content value tends to be stable is taken as the final selected value of the mineral oil content.

[0065] In the embodiment, according to the preselected value of the mineral oil content of each sampling, the relationship between the mineral oil content and the sampling time is obtained, so as to determine the preselected value of the mineral oil content when the mineral oil content tends to be stable, and the largest preselected value of the mineral oil content is taken as the final selected value of the mineral oil content.

[0066] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. It is particularly pointed out that any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A transformer winding residual mineral oil content estimation system, characterized by, The device comprises an oil tank, a transformer winding, a sampling bottle, an oil taking channel, a power supply module, a control module and an upper computer. The oil tank is refilled with natural ester after discharging mineral oil. The power supply module is connected to both ends of the transformer winding through wires. The control module controls the oil taking channel to open every preset time interval to make the sampling bottle take out a preset volume of mixed insulation liquid from the oil tank. The upper computer tests the viscosity of the mixed insulation liquid taken out each time to obtain the viscosity value of the mixed insulation liquid taken out each time.

2. The transformer winding residual mineral oil content estimation system of claim 1, wherein, The transformer winding comprises a core and copper wires wrapped with insulation paper.

3. The transformer winding residual mineral oil content estimation system of claim 2, wherein, The transformer winding is grounded.

4. The transformer winding residual mineral oil content estimation system of claim 1, wherein, The device further comprises a natural ester tank and an oil inlet channel. The control module controls the oil inlet channel to open to make the natural ester in the natural ester tank enter the oil tank. The device further comprises a temperature sensor.

5. The transformer winding residual mineral oil content estimation system of claim 1, wherein, The temperature sensor is installed on the inner wall of the oil tank. The temperature sensor monitors the temperature at the upper end of the oil tank in real time and triggers power-off when the temperature exceeds a preset temperature value to make the power supply module stop supplying power. The oil tank comprises a tank body and a sealing cover.

6. The transformer winding residual mineral oil content estimation system of claim 1, wherein, The viscosity test of the mixed insulation liquid taken out this time comprises:

7. The transformer winding residual mineral oil content estimation system of claim 1, wherein, The viscosity of the mixed insulation liquid taken out this time is tested several times to obtain several test results. The average value of the test results is taken as the viscosity value of the mixed insulation liquid taken out this time. The determination of the final value of the mineral oil content based on all the preselected values of the mineral oil content comprises:

8. The transformer winding residual mineral oil content estimation system of claim 1, wherein, The relationship between the mineral oil content and the sampling time is obtained based on all the preselected values of the mineral oil content. The preselected value of the mineral oil content when the mineral oil content value tends to be stable is determined based on the relationship between the mineral oil content and the sampling time. The final value of the mineral oil content is the maximum preselected value of the mineral oil content when the mineral oil content value tends to be stable. ​

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