Transformer and method for researching diffusion behavior of dissolved gas

Abstract

The invention discloses a transformer for researching the diffusion behavior of dissolved gas, the transformer comprises a box body, the box body is provided with an oil injection assembly, a heating assembly, a circulation assembly, an injection assembly and a sampling assembly, the oil injection assembly is used for inputting transformer oil, and the heating assembly is used for locally heating the transformer oil in the box body; the transformer oil in the box body generates natural oil circulation, the circulation assembly is arranged on one side of the box body and used for providing power and a circulation path to enable the transformer oil in the box body to achieve forced oil circulation, and the injection assembly is used for injecting fault gas at different speeds or transformer oil containing dissolved fault gas. The sampling assembly is used for taking out transformer oil containing dissolved gas after diffusion in the oil tank as a detection sample, so that the diffusion characteristic of the dissolved gas and the dynamic change condition of spatial distribution of fault gas corresponding to the fault occurrence degree and the fault development degree in the transformer along with time are further considered.

Description

Technical Field

[0001] The invention relates to the technical field of transformer monitoring, and in particular to a transformer and a method for studying dissolved gas diffusion behavior. Background Art

[0002] Power transformers are the core equipment of the power grid system, and are also the most expensive, complex and important equipment. Once a power transformer fails, it may cause sudden large-scale power outages, or even cause accidents such as explosions and fires, resulting in direct and indirect economic losses of hundreds of millions of yuan and causing serious adverse social impacts. However, because transformers are located at the center of the power grid and have a complex operating environment, they are often impacted by various adverse operating conditions and are more prone to failure.

[0003] The power transformer is a complex system composed of oil, paper, copper, steel, iron and other materials. The performance and status of the power transformer components and materials will gradually deteriorate due to the long-term complex operating conditions, and will be reflected in a variety of physical and chemical parameters. The use of sensors to accurately sense the changes in multiple physical and chemical characteristic parameters is a prerequisite for equipment status assessment and fault diagnosis. Since the transformer will inevitably be affected by electrical, thermal and mechanical stresses during operation, resulting in thermal or electrical failures in the transformer, the insulating oil and insulating paper in the transformer will decompose to produce low molecular hydrocarbons, H2, CO and CO2 and other gases. The oil is not yet saturated, and the decomposed gases will dissolve in the transformer oil in the form of molecules. Some of these gases can reflect the transformer failure situation. These gases are usually called characteristic gases, which are H2, CH4, C2H6, C2H4, C2H2, CO, CO2. When a fault occurs inside the transformer, the content, composition and gas production rate of the dissolved gas in the oil depend on the severity of the fault and the form of energy release at the fault point. Therefore, the results of gas chromatography analysis can be used to determine whether the equipment has an internal fault, diagnose the fault type, and infer the severity and development trend of the fault. This method is called Dissolved Gases Analysis (DGA). As one of the fault analysis methods commonly used by the power system for oil-immersed power equipment, it is effective in diagnosing latent faults inside the transformer and their development. With the continuous improvement of the capacity and voltage level of power transformers, the equipment failure rate has also shown a significant increasing trend. The existing transformer fault diagnosis method represented by the three-ratio method of dissolved gas in oil is based on a large amount of operating experience data. In the face of increasingly complex operating conditions, the ability to diagnose and predict fault types needs to be further improved. With the introduction of digital design and operation and maintenance requirements for power equipment, higher requirements are placed on the ability to deduce the occurrence and development process of faults.

[0004] However, the internal structure of the transformer is complex, and the physical gas sensor is difficult to install. The types and number of internal sensors are very small, and the general sensor data are local location points, and distributed sensor data cannot be obtained. The DGA diagnostic method in the project is carried out by taking oil samples and sampling analysis, but the number and distribution of oil sample sampling positions are very limited, which cannot reflect the diffusion of dissolved gas in the transformer oil channel, and thus cannot obtain the spatial time-varying distribution law of gas inside the transformer. The test results of the oil sample are difficult to accurately reflect the occurrence and development process of the transformer fault. In terms of testing, the existing DGA test devices for dissolved gas in transformer oil generally use a single oil sampling position for oil sampling, and use the dissolved gas content in the equilibrium state as the basis for DGA diagnosis. It does not fully consider the diffusion characteristics of dissolved gas and the dynamic changes in the spatial distribution of fault gas in the transformer corresponding to the degree of fault occurrence and fault development over time. Summary of the invention

[0005] The present invention provides a transformer and method for studying the diffusion behavior of dissolved gas, which are used to solve how to further consider the diffusion characteristics of dissolved gas and the dynamic changes over time in the spatial distribution of fault gas in the transformer corresponding to the degree of fault occurrence and the degree of fault development.

[0006] The present invention provides a transformer for studying the diffusion behavior of dissolved gases, comprising a box body, on which an oil injection component, a heating component, a circulation component, an injection component and a sampling component are arranged;

[0007] The oil injection assembly is used to input transformer oil;

[0008] The heating assembly includes a heater, which is arranged on one side of the box body and is used to locally heat the transformer oil in the box body, so that a high-temperature zone and a low-temperature zone are formed inside the box body, and the transformer oil in the high-temperature zone flows to the low-temperature zone, generating a natural oil circulation;

[0009] The circulation assembly includes two circulation ports, a circulation pipe and a circulation pump. The two circulation ports are arranged on one side of the box body. The two ends of the circulation pipe are respectively connected to the two circulation ports to achieve communication between the circulation pipe and the box body. The circulation pump is arranged in the middle of the circulation pipe. The circulation pump is used to provide power to make the transformer oil in the box body enter the circulation pipeline and then enter the box body through the circulation pipe, thereby achieving forced oil circulation in the box body.

[0010] The injection assembly is used to inject fault gas at different speeds or transformer oil containing dissolved fault gas;

[0011] The sampling assembly is used to obtain transformer oil containing dissolved gas after diffusion in the box as a test sample.

[0012] Furthermore, the heater is a resistance heater, and the heating component also includes a lead and a power supply. The resistance heater is arranged inside the box, and the power supply is arranged outside the box. The two ends of the resistance heater are respectively connected to the positive and negative poles of the power supply through the two leads.

[0013] Furthermore, the heating component also includes a first temperature monitor and a second temperature monitor, wherein the first temperature monitor is fixed on one side of the resistance heater and is used to monitor the temperature of the transformer oil near the resistance heater after heating; the second temperature monitor is movably arranged and is used to monitor the temperature at different positions along the flow direction of the transformer oil of the natural oil circulation.

[0014] Furthermore, the circulation component also includes a flow rate monitor, which is arranged on one side of the circulation pump and is used to detect the flow rate of the transformer oil in the circulation pipeline.

[0015] Furthermore, the injection assembly includes at least one injection port, which is arranged on the transformer box, and an elastic plug is provided at the injection port. A self-sealing puncture part is provided in the middle of the elastic plug, and the self-sealing puncture part is used to connect with a needle-type pressure injector, so that the fault gas or transformer oil containing dissolved fault gas is injected into the box from the self-sealing puncture part under pressure.

[0016] Furthermore, the sampling assembly includes a plurality of oil extraction ports, which are arranged at equal intervals on the side of the box along the natural oil circulation direction or the forced oil circulation direction.

[0017] A method for studying dissolved gas diffusion behavior comprises the following steps:

[0018] Allowing the transformer oil in the box to circulate naturally or forcibly;

[0019] After the flow field is stabilized, inject the fault gas or transformer oil containing dissolved fault gas;

[0020] After the fault gas diffuses in the box for a preset time, sampling the transformer oil in the box;

[0021] The concentration of oil samples at different time points and locations is tested by gas chromatography analysis to obtain the diffusion law of fault gas in transformer oil under natural oil circulation or forced oil circulation.

[0022] Furthermore, the method for achieving natural oil circulation until the flow field is stable includes:

[0023] The heating component heats the local transformer oil in the box to generate natural oil circulation of the transformer oil;

[0024] After the local transformer oil is heated to the preset temperature, the temperature at different positions is monitored multiple times along the transformer oil flow direction of natural oil circulation;

[0025] If the temperatures at the different positions reach the stable range for multiple times in succession, the flow field of the transformer oil in the box is stable.

[0026] Further, the method for forcing oil circulation to achieve flow field stability includes:

[0027] The circulation component provides power and circulation path to force transformer oil to circulate;

[0028] Measure the flow rate at the circulation component several times;

[0029] If the flow velocity at the circulation component reaches within the stable range for multiple times in succession, the flow field of the transformer oil in the tank is stable.

[0030] Furthermore, the method of injecting fault gas or transformer oil containing dissolved fault gas comprises:

[0031] By injecting a preset amount of fault gas or transformer oil containing dissolved fault gas for a short period of time, the state of sudden fault occurrence is simulated. By injecting a preset amount of fault gas or transformer oil containing dissolved fault gas for a longer period of time, the state of latent fault occurrence is simulated.

[0032] It can be seen from the above technical solutions that the present invention has the following advantages:

[0033] (1) In this embodiment, the transformer oil in the box is locally heated by the heating component, so that the transformer oil in the heated area and the transformer oil in the unheated area inside the box form a significant temperature difference. The generation of this temperature difference promotes the flow of the transformer oil, thereby triggering the natural oil circulation phenomenon. The circulation component further provides power and a circulation path to force the transformer oil in the box to circulate. Therefore, in addition to simulating the forced oil circulation phenomenon, the transformer of this embodiment can also simulate the natural oil circulation phenomenon, fully considering the diffusion characteristics of dissolved gas in the actual transformer operation process.

[0034] (2) This embodiment can simulate the occurrence of a fault type with a larger degree and a larger energy release by directly injecting fault gas through the injection component; this embodiment can simulate the occurrence of a fault type with a smaller degree and a smaller energy release by injecting transformer oil with dissolved fault gas through the injection component; this embodiment can simulate the occurrence of a sudden fault type by injecting fault gas with a larger speed or transformer oil with dissolved fault gas through the injection component; this embodiment can simulate the occurrence of a latent fault type by injecting fault gas with a smaller speed or transformer oil with dissolved fault gas. Therefore, this embodiment injects fault gas or transformer oil containing dissolved fault gas at different speeds through the injection component to simulate the dynamic change of the spatial distribution of fault gas in the transformer with time corresponding to different fault occurrence and development degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 A front view of a transformer structure for studying dissolved gas diffusion behavior provided by an embodiment of the present invention;

[0037] Figure 2 A top view of a transformer structure for studying dissolved gas diffusion behavior provided by an embodiment of the present invention;

[0038] Figure 3 A right view of a transformer structure for studying dissolved gas diffusion behavior provided by an embodiment of the present invention;

[0039] Figure 4 A glass syringe provided by an embodiment of the present invention;

[0040] Figure 5 A micro-injector provided by an embodiment of the present invention;

[0041] Figure 6 A schematic diagram of a flow chart of an oil sample extraction method provided by an embodiment of the present invention;

[0042] Figure numerals: 1. Oil level gauge; 2. Heating resistor wire; 3. High-pressure bushing; 4. Low-pressure bushing; 5. Two-way valve; 6. Oil sample valve; 7. Thermometer; 8. Box; 9. Screw; 10. Temperature sensor; 11. Tripod; 12. Oil circulation interface; 13. Connecting pipe; 14. Three-way ball valve; 15. Syringe. DETAILED DESCRIPTION

[0043] The embodiment of the present invention provides a transformer and a method for studying the diffusion behavior of dissolved gases, which are used to solve the technical problem.

[0044] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and drawings of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the implementation of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0046] See also Figure 1-Figure 3 A transformer for studying the diffusion behavior of dissolved gas provided by an embodiment of the present invention comprises a box 8, on which an oil injection assembly, a heating assembly, a circulation assembly, an injection assembly and a sampling assembly are arranged; the oil injection assembly is used to input transformer oil, the heating assembly is used to locally heat the transformer oil in the box 8, so that the transformer oil inside the box 8 generates natural oil circulation, the circulation assembly is arranged on one side of the box 8, and is used to provide power and a circulation path to force the transformer oil in the box 8 to realize forced oil circulation, the injection assembly is used to inject fault gas at different speeds or transformer oil containing dissolved fault gas, and the sampling assembly is used to obtain the transformer oil containing dissolved gas after diffusion in the box 8 as a test sample:

[0047] It is understandable that, in specific implementation, this embodiment partially heats the transformer oil in the box 8 through the heating component, so that the transformer oil in the heated area and the transformer oil in the unheated area inside the box 8 form a significant temperature difference. The generation of this temperature difference promotes the flow of the transformer oil with a higher temperature to the transformer oil with a lower temperature, thereby causing the natural oil circulation phenomenon. Further, the transformer oil in the box 8 is forced to circulate by providing power and a circulation path through the circulation component. Therefore, the transformer of this embodiment can simulate the natural oil circulation phenomenon in addition to simulating the forced oil circulation phenomenon, and fully considers the diffusion characteristics of dissolved gas in the actual transformer operation process.

[0048] It can be further understood that, this embodiment can simulate the occurrence of a fault type with a larger degree and a larger energy release by directly injecting fault gas through the injection component; this embodiment can simulate the occurrence of a fault type with a smaller degree and a smaller energy release by injecting transformer oil in which fault gas has been dissolved through the injection component; this embodiment can simulate the occurrence of a sudden fault type by injecting fault gas with a larger speed or transformer oil in which fault gas has been dissolved through the injection component; this embodiment can simulate the occurrence of a latent fault type by injecting fault gas with a smaller speed or transformer oil in which fault gas has been dissolved. Therefore, this embodiment uses the injection component to inject fault gas or transformer oil containing dissolved fault gas at different speeds to simulate the dynamic change of the spatial distribution of fault gas in the transformer corresponding to different fault occurrence degrees and development degrees over time.

[0049] In a more specific embodiment, the box body 8 includes a steel shell and an upper cover plate, the upper cover plate is connected to the threaded holes of the shell through 26 screws 9, and four tripods 11 are installed at the bottom of the box body 8.

[0050] In a more specific embodiment, the oil filling assembly includes an oil filling port, which is arranged on the upper cover plate and is used to input transformer oil from the top of the box body 8.

[0051] In a more specific embodiment, an oil level gauge 1 is also provided on the upper cover plate, and the oil level gauge 1 is used to judge whether the oil is fully filled when injected, and to judge whether the oil is too little after sampling. If it is too little, oil should be added to avoid affecting the accuracy of gas concentration measurement.

[0052] In a more specific embodiment, the socket of the oil level gauge 1 is the transformer oil filling port. It is understandable that when oil filling is needed, the oil level gauge is taken out for oil filling to avoid too many holes in the box 8 to increase the risk of oil leakage.

[0053] In a more specific embodiment, the heating assembly includes a resistance heater, a lead wire and a power supply, the resistance heater is arranged inside the box 8, the power supply is arranged outside the box 8, and the two ends of the resistance heater are respectively connected to the positive and negative poles of the power supply through two lead wires. It can be understood that in the actual operation of the transformer, the transformer winding is made of conductive materials such as copper or aluminum. When the current passes through the winding, since the winding itself has a certain resistance, according to Joule's law (Q = I²Rt, where Q represents heat, I is current, R is resistance, and t is time), the current does work on the resistance and converts electrical energy into heat energy. Therefore, the resistance loss of the winding will cause local heat generation inside the transformer. Therefore, this embodiment heats the local transformer oil in the transformer by setting a resistance heater, which fully simulates the resistance heat generation of the components during the actual operation of the transformer.

[0054] In a more specific embodiment, the resistance heater is a heating resistor wire 2, and the material of the heating resistor wire 2 is copper or aluminum. The upper cover plate is provided with A, B, C three-phase high-voltage bushings 3, and a, b, c three-phase and neutral low-voltage bushings 4, the high and low voltage bushings are used to insulate the three-phase winding and the outlet of the heating resistor wire 2, the leads at both ends of the heating resistor wire 2 are respectively led out through the A and B two-phase high-voltage windings, and further connected to a 24V adjustable power adapter, the heating resistor wire 2 is arranged at the top of the transformer box 8, and the heating power is adjusted by the power adapter so that the temperature at the top of the transformer reaches a preset temperature. The preset temperature is set according to the heating temperature of the transformer in actual operation. In this embodiment, the heating resistor wire 2 is arranged at the top, which is convenient for leading the heating resistor wire and the A and B two-phase high-voltage windings. Due to the uneven temperature distribution of the upper and lower layers in the transformer box 8, the transformer oil is driven by the temperature to perform natural oil circulation, which fully simulates the actual process of the transformer, and the resistance heat generation of the winding causes the natural oil circulation.

[0055] In a more specific embodiment, the heating assembly also includes a first temperature monitor and a second temperature monitor. The first temperature monitor is fixed on one side of the resistance heater and is used to monitor the temperature of the transformer oil nearby after heating by the resistance heater; the second temperature monitor is movably arranged and is used to monitor the temperature at different positions along the flow direction of the transformer oil of the natural oil circulation.

[0056] In a more specific embodiment, the first temperature monitor is a temperature sensor 10, which is disposed on the top of the transformer and is used to determine whether the top oil temperature after being heated by the heating resistance wire 2 reaches a preset temperature.

[0057] In a more specific embodiment, the second temperature monitor is a thermometer 7. It can be understood that since the heating resistor 2 is heated at the top of the transformer, the natural oil circulation flow direction is from hot to cold, that is, the flow direction of the transformer oil in the tank 8 is from top to bottom. The thermometer 7 can move up and down to measure the temperature at any height position in the vertical direction inside the transformer.

[0058] It is further understood that the flow field inside the transformer is usually stable during actual operation. Therefore, in the simulation experiment, the fault gas is injected only after the flow field is stable. The test data obtained in this way is closer to the actual situation of the transformer. When conducting the natural oil circulation experiment, it is impossible to set a measuring tool for measuring the flow rate in the box 8. Therefore, whether the flow field is stable is judged by judging the temperature state of the transformer oil. After the temperature sensor 10 at the top determines that the temperature at the top is maintained at the preset temperature, the temperature at different positions in the vertical direction is measured by the thermometer 7 to see whether they are all in a stable state. If so, it can be judged that the flow field is stable, and the next step of inputting the fault gas is performed. Usually, the temperature at different positions in the vertical direction is continuously monitored and kept unchanged for 1 hour, and then it is considered to be in a stable state, that is, the flow field is considered to be stable.

[0059] In a more preferred embodiment, the circulation component includes two circulation ports, a circulation pipe, a circulation pump and a flow rate monitor. The circulation port is arranged on one side of the box 8, and the two ends of the circulation pipe are respectively connected to the two circulation ports. The circulation pump is arranged in the middle of the circulation pipe, and the flow rate monitor is arranged on one side of the circulation pump.

[0060] In a more specific embodiment, a two-way valve 5 is provided at the circulation port, the circulation pipe is a hose, and the circulation pump is an electric pump. The two two-way valves 5 are connected by a hose, and an electric pump is installed on the pipeline to force oil circulation in the transformer box 8. In a more specific embodiment, a flow rate sensor is added on the pipeline and next to the electric pump, and the flow rate sensor is used to determine whether the flow field inside the transformer is stable. The next step of inputting fault gas operation is performed only after the flow field is stable. It is understandable that if the flow rate at the circulation pipe reaches a stable range for multiple consecutive times, the flow field of the transformer oil in the box 8 is stable. Normally, if the flow rate at the circulation pipe is measured for multiple consecutive times and is the same or similar value, the flow field of the transformer oil in the box 8 is stable. In some more specific embodiments, the flow rate monitor includes an electromagnetic flowmeter, an ultrasonic flowmeter, a turbine flowmeter or a vortex flowmeter, etc.

[0061] In a more specific embodiment, the injection assembly includes at least one injection port, which is arranged on the transformer box 8. An elastic plug is provided at the injection port. A self-sealing puncture portion is provided in the middle of the elastic plug. The self-sealing puncture portion is used to insert the needle portion of a needle-type pressure injector, so that the fault gas or transformer oil containing dissolved fault gas is injected into the box 8 from the self-sealing puncture portion under the pressure of the pressure injector.

[0062] In a more specific embodiment, the pressure syringe is a glass syringe, such as Figure 4 shown.

[0063] It is understandable that, since the transformer is full of oil and the injection port pressure is high, an elastic plug with a self-sealing puncture site is provided on the injection hole. When the needle-type pressure injector is inserted into the self-sealing puncture site to deliver gas or oil, the elastic plug has great elasticity and can fit closely with the needle tube when the needle tube is inserted, thereby preventing transformer oil from leaking from the gap between the elastic plug and the needle tube. In some more specific embodiments, the elastic plug is a rubber plug, a silicone plug, a thermoplastic elastomer plug, or the like.

[0064] In a more specific embodiment, the injection port is provided with a sealing cover, and the sealing cover is provided on the outside of the elastic plug body. It can be understood that when no liquid or gas injection is performed, the injection port is completely sealed to reduce the risk of oil leakage.

[0065] In a more specific embodiment, injection ports are set at different locations on the transformer to simulate different origin points of faults in the transformer, and the location of the transformer fault can be determined later by the gas diffusion law.

[0066] In a more specific embodiment, the syringe power end is connected to a microinjection pump, such as Figure 5 As shown, the micro-injection pump can adjust the injection parameters to achieve timed and quantitative injection of gas or transformer oil containing dissolved gas.

[0067] It is understandable that:

[0068] (1) By injecting different gas types, the fault type inside the transformer can be simulated. For example, injecting methane and ethane gases can simulate the occurrence of thermal faults, while injecting hydrogen can simulate the occurrence of electrical faults.

[0069] (2) Simulate the severity of the internal fault of the transformer by directly injecting fault gas or transformer oil dissolved with fault gas. For example, when the transformer overheats and the temperature is not particularly high, the insulation material will gradually produce a small amount of low-molecular gas when heated. These gases can be dissolved in the transformer oil at a certain temperature and pressure; when the transformer has a low-energy discharge fault such as partial discharge, the gas produced is hydrogen. When the fault develops slowly, hydrogen can be dissolved in the oil. For this kind of low-level fault, it is necessary to directly inject oil dissolved with special gas into the transformer to obtain accurate low-fault gas diffusion data.

[0070] When a transformer has a serious overheating fault and the temperature rises sharply, a large amount of gas is generated. The speed at which these gases are generated is very fast, exceeding their dissolution rate in the transformer oil, and they will form a steam bag and will not dissolve in the transformer oil. When high-energy discharge faults such as arc discharge occur, a large amount of high-temperature and high-pressure gas will be generated instantly. These gases are generated at an extremely fast speed and cannot be dissolved in the transformer oil in time, but form bubbles that expand rapidly inside the transformer. Therefore, for this kind of high-level fault, it is necessary to directly inject gas into the transformer to obtain accurate data on the diffusion of severe fault gas.

[0071] (3) Transformer fault types also include sudden faults and latent faults. When a sudden fault occurs, the gas is generated at a faster rate. At this time, when injecting gas or liquid containing gas, the injection rate should be increased. When a latent fault occurs, the gas is generated at a slower rate. At this time, when injecting gas or liquid containing gas, the injection rate should be reduced. Therefore, for sudden faults and latent faults, the appropriate injection rate should be adjusted to accurately obtain gas diffusion data that reflects the development trend of the fault.

[0072] In a more specific embodiment, the sampling assembly includes an oil sampling port, which is provided with an oil sample valve 6. The oil sample valve 6 is composed of a valve body, a valve core, and a sealing member. When it is necessary to extract an oil sample, the valve core is controlled by an operating mechanism. The valve core moves inside the valve body to open the corresponding channel. At this time, the sealing member ensures that no oil leakage occurs during the movement of the valve core and when the channel is open. Under the action of pressure, the oil flows out of the open channel and enters the oil sample collection device. When it is not necessary to extract the oil sample, the valve core moves back to its position, closing the channel, and the sealing member functions again to ensure the sealing of the entire system and prevent abnormal outflow of oil and entry of external impurities.

[0073] The oil sample valve 6 is equipped with a three-way ball valve 14 through the connecting pipe 13. After gas or transformer oil with dissolved gas is injected into the box 8, oil samples are extracted from the three-way ball valve 14 at fixed intervals. The extraction operation is carried out in accordance with the oil sampling method GB7252: the syringe 15 is inserted into the interface of the three-way ball valve 14 and fixed, and the three-way ball valve 14 is adjusted to communicate with the box 8 and the side end valve port, and the connecting pipeline is flushed, and then the syringe 15 and the box 8 are connected, and the syringe 15 is flushed, and then the three-way ball valve 14 is adjusted to communicate with the side end valve port, and the oil sample in the syringe 15 is emptied, and then the syringe is connected to the box 8, and 40ml of oil sample is taken out. The connection operation diagram is as shown in Figure 6 shown.

[0074] In a more specific embodiment, a plurality of oil extraction ports are arranged at equal intervals from top to bottom on each side of the box body 8. It can be understood that the forced oil circulation direction and the natural oil circulation direction of the present embodiment are both carried out in the vertical direction of the box body 8. Therefore, a plurality of oil sample valves 6 are arranged at equal intervals from top to bottom on each side of the box body 8. The difference in concentration of transformer fault gas at different heights can be obtained, the number of sampling samples can be increased, and the diffusion law of the fault gas in the transformer box can be obtained more accurately.

[0075] It should be noted that after sampling, the concentration of oil samples at different time points and locations is tested by gas chromatography analysis method to obtain the gas diffusion laws in oil for different types of faults, faults of different severity, and faults with different development trends under natural oil circulation or forced oil circulation.

[0076] In a more specific embodiment, an outlet is provided at the bottom of the box 8, which is used to discharge all the transformer oil in the box 8 from the outlet when the gas content of the transformer oil in the transformer cannot meet the requirements for a new round of laboratory testing, and replace new transformer oil at the oil filling port of the upper end cover.

[0077] In a more specific embodiment, the operation method of the natural oil circulation test is:

[0078] S01, after the box 8 is filled with oil, the power adapter of the heating resistor 2 is turned on to make the heating resistor 2 continue to heat up, and the thermometer 7 and the temperature sensor 10 are observed. The oil temperature at the top of the transformer is stabilized within the preset temperature by adjusting the power. At this time, the oil in the box 8 is naturally circulated under the drive of temperature;

[0079] S02, after the temperature and flow field in the oil are stable, keep the heating resistor 2 in a continuous heating state, and inject the fault gas or transformer oil in which the fault gas is dissolved;

[0080] S03, after the fault gas diffuses in the transformer for a preset time, oil sampling is performed at each oil extraction port of the transformer at fixed intervals;

[0081] S04. Use gas chromatography analysis to detect the concentration of oil samples at different time points and locations to obtain the gas diffusion law in oil under natural oil circulation.

[0082] In a more specific embodiment, the preset time is 30 minutes and the fixed time is 15 minutes.

[0083] In a more specific embodiment, the forced oil circulation operation method is:

[0084] S01. The circulation ports on both sides of the box 8 are connected through the circulation pipe, and the circulation pump on the circulation pipe is started. The flow rate of the oil in the pipeline is controlled by adjusting the circulation pump to realize the forced oil circulation of the oil inside the transformer;

[0085] S02, after the flow field inside the transformer is stabilized, injecting fault gas or transformer oil in which fault gas is dissolved;

[0086] S03. After the fault gas diffuses in the transformer for a preset time, oil samples are extracted from each oil extraction port of the transformer at fixed intervals.

[0087] S04. The concentration of oil samples at different time points and locations is tested by gas chromatography analysis to obtain the diffusion law of gas in oil under forced oil circulation.

[0088] In a more specific embodiment, the preset time is 30 minutes and the fixed time is 15 minutes.

[0089] In a more specific embodiment, the gas injection method is:

[0090] S201, inserting the needle end of the pressure syringe into the self-sealing puncture site at the injection port at the designated position.

[0091] S202, installing the pressure syringe on the micro-injection pump, setting the flow rate of the micro-injection pump, and performing timed and quantitative gas injection.

[0092] It should be noted that adjusting the injection pump parameters to achieve rapid gas injection to simulate sudden transformer failure, at this time the injector gas production time is short and the instantaneous gas production volume is large; adjusting the injection pump parameters to achieve slow gas injection to simulate latent transformer failure, at this time the injector gas production duration is long and the gas production speed is slow.

[0093] Oil filling method:

[0094] S211. Insert the needle end of the pressure syringe into the self-sealing puncture site at the injection port at the designated position.

[0095] S212, install the pressure syringe on the micro-injection pump, set the flow rate of the micro-injection pump, and perform timed and quantitative oil injection.

[0096] It should be noted that the oil injection at this time is a small amount of oil sample injection, which is used to inject oil samples dissolved with characteristic gases to simulate the phenomenon of fault gas production. The amount of oil injected is small. Install the syringe on the micro-injection pump, set the flow rate of the micro-injection pump, and perform timed and quantitative oil sample injection.

[0097] The redundant space of the transformer itself limits the amount of oil injected, so the amount of oil injected needs to be considered. The purpose of oil injection is to dissolve the gas in the oil and inject it into the transformer to simulate the gas production phenomenon when the actual transformer fails. The oil injection rate and the concentration of the dissolved gas in the oil need to reflect the actual fault gas production rate, so the oil injection rate, time and total amount need to be controlled.

[0098] Adjust the injection pump parameters to adjust the oil injection speed. Rapid oil injection simulates sudden transformer failure. At this time, the injector produces oil for a short time and the instantaneous oil production is large. Adjust the injection pump parameters to achieve slow oil injection to simulate latent transformer failure. At this time, the injector produces oil for a long time and the oil production speed is slow.

[0099] In a more specific embodiment, the method for extracting oil samples by a dissolved gas diffusion process:

[0100] A three-way ball valve 14 is installed at the oil sample valve 6 on the front and side of the box 8 through a connecting pipe 13. After the fault gas is injected into the box 8, oil samples are extracted from the three-way ball valve 14 at fixed intervals. The extraction operation is carried out in accordance with the oil sampling method GB7252:

[0101] Insert the syringe 15 into the interface of the three-way ball valve 14 and fix it. Adjust the three-way ball valve 14 until the box 8 is connected to the side valve port, flush the connecting pipeline, and then connect the syringe 15 and the box 8 to flush the syringe 15. Then adjust the three-way ball valve 14 to connect the syringe 15 with the side valve port, empty the oil sample in the syringe 15, and then connect the syringe to the box 8 to take out 40ml of oil sample. The connection operation diagram is shown as follows: Figure 6 As shown. Considering that the liquid level in the box 8 drops after multiple oil samplings, after each oil sampling, a glass syringe is filled with new oil and connected to the oil filling port of the upper cover plate, and the oil is slowly injected for oil replenishment.

[0102] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A transformer for studying the diffusion behavior of dissolved gases, characterized in that: It comprises a box body, on which an oil filling component, a heating component, a circulation component, an injection component and a sampling component are arranged; The oil injection assembly is used to input transformer oil; The heating assembly includes a heater, which is arranged on one side of the box body and is used to locally heat the transformer oil in the box body, so that a high-temperature zone and a low-temperature zone are formed inside the box body, and the transformer oil in the high-temperature zone flows to the low-temperature zone, generating a natural oil circulation; The circulation assembly includes two circulation ports, a circulation pipe and a circulation pump. The two circulation ports are arranged on one side of the box body. The two ends of the circulation pipe are respectively connected to the two circulation ports to achieve communication between the circulation pipe and the box body. The circulation pump is arranged in the middle of the circulation pipe. The circulation pump is used to provide power to make the transformer oil in the box body enter the circulation pipeline and then enter the box body through the circulation pipe, thereby achieving forced oil circulation in the box body. The injection assembly is used to inject fault gas at different speeds or transformer oil containing dissolved fault gas; The sampling assembly is used to obtain transformer oil containing dissolved gas after diffusion in the box as a test sample.

2. A transformer for studying the diffusion behavior of dissolved gases according to claim 1, characterized in that: The heater is a resistance heater, and the heating component also includes a lead and a power supply. The resistance heater is arranged inside the box, and the power supply is arranged outside the box. The two ends of the resistance heater are respectively connected to the positive and negative poles of the power supply through the two lead wires.

3. A transformer for studying the diffusion behavior of dissolved gases according to claim 2, characterized in that: The heating component also includes a first temperature monitor and a second temperature monitor. The first temperature monitor is fixed on one side of the resistance heater and is used to monitor the temperature of the transformer oil near the resistance heater after heating; the second temperature monitor is movably arranged and is used to monitor the temperature at different positions along the flow direction of the transformer oil in the natural oil circulation.

4. A transformer for studying the diffusion behavior of dissolved gases according to claim 1, characterized in that: The circulation component further comprises a flow rate monitor, which is arranged on one side of the circulation pump and is used to detect the flow rate of the transformer oil in the circulation pipeline.

5. A transformer for studying dissolved gas diffusion behavior according to claim 1, characterized in that: The injection assembly includes at least one injection port, which is arranged on the transformer box. An elastic plug is provided at the injection port. A self-sealing puncture part is provided in the middle of the elastic plug. The self-sealing puncture part is used to be connected to a needle-type pressure injector, so that the fault gas or transformer oil containing dissolved fault gas is injected into the box from the self-sealing puncture part under pressure.

6. A transformer for studying dissolved gas diffusion behavior according to claim 1, characterized in that: The sampling assembly comprises a plurality of oil extraction ports, which are arranged at equal intervals on the side of the box along the natural oil circulation direction or the forced oil circulation direction.

7. A method for studying dissolved gas diffusion behavior using the transformer according to any one of claims 1 to 6, characterized in that: The following steps are involved: Allowing the transformer oil in the box to circulate naturally or forcibly; After the flow field is stabilized, inject the fault gas or transformer oil containing dissolved fault gas; After the fault gas diffuses in the box for a preset time, sampling the transformer oil in the box; The concentration of oil samples at different time points and locations is tested by gas chromatography analysis to obtain the diffusion law of fault gas in transformer oil under natural oil circulation or forced oil circulation.

8. A method for studying dissolved gas diffusion behavior according to claim 7, characterized in that: The method for achieving natural oil circulation and flow field stability comprises: The heating component heats the local transformer oil in the box to generate natural oil circulation of the transformer oil; After the local transformer oil is heated to the preset temperature, the temperature at different positions is monitored multiple times along the transformer oil flow direction of natural oil circulation; If the temperatures at the different positions reach the stable range for multiple times in succession, the flow field of the transformer oil in the box is stable.

9. A method for studying dissolved gas diffusion behavior according to claim 8, characterized in that: The method for forcing oil circulation to achieve flow field stability includes: The circulation component provides power and a circulation path to force transformer oil to circulate; measuring the flow rate at the circulation component a plurality of times; If the flow rate at the circulation component reaches within the stable range for multiple times in succession, the flow field of the transformer oil in the box is stable.

10. The method for studying dissolved gas diffusion behavior according to claim 7, characterized in that: The method of injecting fault gas or transformer oil containing dissolved fault gas comprises: By injecting a preset amount of fault gas or transformer oil containing dissolved fault gas for a short period of time, the state of sudden fault occurrence is simulated. By injecting a preset amount of fault gas or transformer oil containing dissolved fault gas for a longer period of time, the state of latent fault occurrence is simulated.

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