Transformer oil circulating plasma-enhanced method and system

Abstract

The present application relates to transformer oil circulation plasma enhanced method and system, the present application is arranged in the oil tank oil channel of transformer oil medium barrier discharge plasma device, the ion wind effect generated by it is used to drive oil accelerated flow circulation, thereby replacing the traditional mechanical oil pump drive. The high voltage electrode of the medium barrier discharge plasma device of the present application is completely wrapped in the dielectric barrier layer, to ensure the safety of discharge, the control unit adjusts the discharge intensity through the sensor, and the quick cut-off protection is carried out in the abnormal time. The process of the medium barrier discharge plasma device of the present application drives oil accelerated circulation synchronously decomposes fault gas in oil, realizes the integration of the dual functions of transformer oil cooling and insulation purification. The present application does not need moving parts, low power consumption, long service life, intelligent, suitable for high voltage grade oil immersed transformer.

Description

Technical Field

[0001] This invention relates to the field of transformer thermal management, and more specifically to methods and systems for enhancing the heat dissipation of transformer oil circulation. Background Technology

[0002] With the continuous improvement of power system voltage levels and transmission capacity, the thermal management performance of oil-immersed transformers, as core equipment of the power grid, directly affects their operational reliability and service life. Traditional oil-immersed transformers generally use mechanical oil pumps to drive transformer oil circulation for heat dissipation. This method has revealed many inherent defects in decades of application: First, as a moving part, the mechanical oil pump suffers from bearing wear and seal aging during long-term operation, accounting for more than 30% of transformer auxiliary equipment failures, and maintenance requires power outages, affecting power supply reliability; Second, the power consumption of the oil pump motor is significant. For ultra-high voltage transformers, the cooling system can consume tens of thousands of kilowatt-hours annually, which does not meet the requirements of power grid energy conservation and emission reduction; Third, the noise and vibration of the oil pump cause environmental problems for urban substations and densely populated residential areas; Finally, existing mechanical oil pumps mostly operate at a fixed speed, making it difficult to adapt to the dynamic changes in transformer load, resulting in over-cooling under light loads and insufficient cooling under heavy loads, and lacking intelligent adjustment.

[0003] In recent years, some studies have attempted to use electric or magnetic fields to drive oil circulation to avoid mechanical parts, but all of these have encountered insurmountable technical obstacles. Regardless of whether electric or magnetic fields are used, existing solutions require the addition of a large number of conductive or magnetic particles to the oil. The former significantly reduces the oil's insulation strength, while the latter (magnetic particles) will interact with the external strong magnetic field, generating electromagnetic interference to the transformer protection device.

[0004] Furthermore, during long-term operation, partial discharge and overheating in transformers can cause the insulating oil to decompose, continuously producing fault-characteristic gases such as C2H2, C2H4, and CH4. The accumulation of these gases in the oil significantly reduces its insulation strength and accelerates its deterioration. Existing technologies often employ offline or independent online degassing devices to treat the oil, but these devices are complex in structure and cannot work in conjunction with the transformer cooling system.

[0005] It is evident that the industry needs better solutions to address the issues of oil-driven and fault gas problems in transformers. Summary of the Invention

[0006] To address at least one technical problem in the background art, the present invention provides a method and system for enhancing plasma circulation in transformer oil.

[0007] The solution of the present invention is as follows:

[0008] A method for enhancing transformer oil circulation with plasma, wherein the transformer includes an oil tank with an oil outlet located at the top and an oil inlet located at the bottom, characterized in that a dielectric barrier discharge plasma device is added inside the oil tank, utilizing the ion wind effect generated by the device to drive the oil to flow faster toward the oil outlet, thereby replacing the mechanical oil pump circulation drive scheme; the dielectric barrier discharge plasma device includes a high-voltage electrode and a ground electrode, wherein the high-voltage electrode is completely wrapped by a dielectric barrier layer to ensure discharge safety.

[0009] The dielectric barrier discharge plasma device of this invention generates non-equilibrium low-temperature plasma to drive the transformer oil to accelerate circulation. At the same time, the active particles in the plasma automatically decompose the fault characteristic gases dissolved in the oil, realizing the integration of the dual functions of improving cooling efficiency and online purification of transformer oil insulation.

[0010] Another solution of the present invention is as follows:

[0011] A transformer oil circulating plasma enhancement system includes a transformer and an external radiator. The transformer includes an oil tank, in which windings and an iron core are installed. The intervals between the windings and the top and bottom of the oil tank are respectively the top main oil passage and the bottom main oil passage. The oil outlet and the oil inlet are respectively located on the upper and lower parts of the side wall of the oil tank. The external radiator is connected to the top main oil passage and the bottom main oil passage through them respectively.

[0012] The enhancement system is characterized by further including a dielectric barrier discharge plasma device, which includes an alternating power supply and an electrode pair. The electrode pair includes a high-voltage electrode and a ground electrode, which are respectively sealed through an insulated power wire after exiting the oil tank and connected to the alternating power supply. The high-voltage electrode is a needle electrode, which is completely wrapped by a dielectric barrier layer. The ground electrode is an arc-shaped plate electrode. The needle and plate electrodes are arranged opposite each other in the top main oil channel. The plate electrode is used to receive hot oil from the transformer windings and core and guide the hot oil to the oil outlet.

[0013] The enhancement system of this invention is an application of the aforementioned enhancement method. After the needle and plate electrodes of the enhancement system of this invention are activated, a non-equilibrium low-temperature plasma is generated between them, forming an ion wind effect and generating a horizontal velocity component, driving the oil to accelerate towards the oil outlet. The arc-shaped plate electrode of this invention serves two purposes: firstly, it acts as a guide plate, guiding the hot oil to flow in a designated direction; secondly, it pairs with the needle electrode to generate a non-equilibrium low-temperature plasma and a horizontal velocity component, driving the oil to accelerate its circulation. In an oil-immersed transformer environment, the guide plate is a necessary component for guiding the hot oil to flow in a designated direction and avoiding flow dead zones. The arc-shaped plate electrode in this invention serves two functions, reducing the number of components and the space occupied in the transformer tank.

[0014] As a preferred embodiment of the present invention: one end of the arc-shaped plate electrode is the inlet end and the other end is the outlet end. Both ends are formed by gradually bending downwards from the horizontal. The inlet end has a larger curvature. The needle electrode is set close to the outlet end to facilitate the flow of driving oil to the oil outlet.

[0015] As a further optimization: the enhancement system also includes a plasma control unit and a sensor for monitoring oil temperature. The sensor is connected to the plasma control unit after passing through the oil tank in an insulated signal wire. The plasma control unit is connected to the alternating power supply.

[0016] The plasma control unit determines the cooling requirement based on the acquired oil temperature and adjusts the output power of the alternating power supply.

[0017] The enhancement system is also equipped with a sensor for monitoring oil quality. This sensor is also connected to the plasma control unit after passing through the oil tank in an insulated signal wire. The plasma control unit adjusts the output power of the alternating power supply based on the fault characteristic gas concentration information obtained through the sensor.

[0018] The enhancement system is also equipped with a sensor for monitoring oil flow rate. This sensor is also connected to the plasma control unit after passing through the oil tank in an insulated signal wire. The plasma control unit adjusts the output power of the alternating power supply based on the oil flow rate information obtained through the sensor.

[0019] The enhancement system also includes a redundant circuit breaker, which is installed in the connection line between the high-voltage electrode and the alternating power supply. The plasma control unit is connected to the redundant circuit breaker. When it detects abnormal oil temperature, oil flow rate, or fault characteristic gas concentration, it controls the redundant circuit breaker to disconnect within <10ms, thereby better ensuring system safety.

[0020] The optimized scheme enhances the intelligence of the system and better ensures its security.

[0021] The top of the oil tank is equipped with a gas collection chamber that communicates with its interior, and the gas collection chamber is controlled to release gas through an exhaust valve.

[0022] Beneficial effects:

[0023] Compared to existing technologies, this invention achieves safe, low-energy-consumption, long-life, and intelligent oil circulation enhancement while avoiding mechanical moving parts, and simultaneously solves the problem of fault gas accumulation. Specifically, it is manifested as follows:

[0024] 1) This invention utilizes the ion wind effect generated by dielectric barrier discharge to drive the transformer oil to accelerate circulation, thereby enhancing oil circulation without mechanical moving parts. By completely encasing the high-voltage electrode within the dielectric barrier layer, discharge safety is ensured, and the problems of bearing wear, seal aging, noise vibration, and energy consumption of traditional oil pumps are completely solved. The total energy consumption of the system is only 5%-8% of that of traditional oil pump cooling, and the failure rate is reduced by more than 90%, enabling maintenance-free and long-life operation of the transformer. This can significantly improve the overall reliability of the transformer. Compared with electric field or magnetic field drive schemes, it avoids the addition of conductive or magnetic particles to the transformer oil, which would affect the safety control of the transformer.

[0025] 2) This invention utilizes dielectric barrier discharge to generate non-equilibrium low-temperature plasma to drive oil accelerated circulation. At the same time, the active particles in the plasma automatically decompose the fault characteristic gases dissolved in the oil, such as C2H2, C2H4, CH4, etc., thus achieving the integration of cooling efficiency improvement and online purification of transformer oil insulation. Compared with independent oil treatment devices, this reduces equipment costs and maintenance complexity.

[0026] 3) The plasma control unit of this invention judges load changes by parameters such as oil temperature, oil quality, and oil flow rate, and realizes adaptive intelligent adjustment of cooling power, which solves the problem of over-cooling or under-cooling caused by the fixed-speed operation of mechanical oil pumps, and can optimize the transformer operating temperature curve. Attached Figure Description

[0027] Figure 1 , 2 This is a schematic diagram of the structure of a transformer oil circulating plasma enhancement system according to a preferred embodiment of the present invention;

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Transformer oil tank; 2. Top main oil passage; 3. Electrode pair; 4. Alternating power supply; 5. Plasma control unit; 6. Temperature sensor array; 7. Oil quality monitoring sensor; 8. Flow rate sensor; 9. Insulated signal wire; 10. Dielectric barrier layer; 11. High voltage electrode; 12. Insulated power wire; 13. Sealing ring; 14. Ground electrode; 15. Redundant circuit breaker; 16. Gas collection chamber; 17. Transformer oil; 18. Winding; 19. Core; 20. Vent valve; 21. Oil inlet; 22. Oil outlet. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. In the present invention, there is no distinction between iron core, iron core, magnetic core, and magnetic core.

[0031] Example 1

[0032] This embodiment addresses the oil-driven and fault gas problems in existing transformer technologies by proposing a solution that achieves safe, long-life, and low-energy-consumption oil circulation enhancement while avoiding mechanical moving parts, and simultaneously solves the problem of fault gas accumulation.

[0033] A method for enhancing transformer oil circulation with plasma is disclosed. The transformer includes an oil tank with an oil outlet at the top and an oil inlet at the bottom. A dielectric barrier discharge plasma device is added inside the oil tank. The ion wind effect generated by the plasma device drives the oil to flow faster towards the oil outlet, thereby replacing the mechanical oil pump circulation drive scheme. The dielectric barrier discharge plasma device includes a high-voltage electrode and a ground electrode. The high-voltage electrode is completely wrapped by a dielectric barrier layer to ensure discharge safety.

[0034] This embodiment primarily replaces the traditional mechanical oil pump drive system with a non-equilibrium low-temperature plasma driven by a dielectric barrier discharge plasma device to accelerate oil circulation. By completely encasing the high-voltage electrodes with a dielectric barrier layer, the system's discharge safety is ensured, completely resolving the issues of bearing wear, seal aging, noise, vibration, and energy consumption inherent in traditional oil pumps. The system's total energy consumption can be reduced to 5%-8% of that of traditional oil pump cooling, and the failure rate can be reduced by over 90%, enabling maintenance-free, long-life operation of the transformer and significantly improving its overall reliability. Compared to electric or magnetic field drive systems, this avoids the addition of conductive or magnetic particles to the transformer oil, which could compromise transformer safety control.

[0035] In this embodiment, a non-equilibrium low-temperature plasma is generated by a dielectric barrier discharge plasma device to drive the transformer oil to accelerate circulation. At the same time, the active particles in the plasma automatically decompose the fault characteristic gases dissolved in the oil, such as C2H2, C2H4, and CH4, into harmless small molecules, avoiding gas accumulation that leads to a decrease in oil insulation strength. This achieves the integration of dual functions: improving cooling efficiency and online purification of transformer oil insulation. Compared with a separate oil treatment device, this reduces equipment costs and maintenance complexity.

[0036] Example 2

[0037] This embodiment aims to provide an application of the enhanced method of Embodiment 1.

[0038] The transformer oil circulation plasma enhancement system in this embodiment is as follows: Figure 1 As shown, the transformer mainly includes an oil tank 1 and an iron core 19 and windings 18 disposed therein. The gaps between the iron core 19 and windings 18 and the top and bottom of the oil tank 1 respectively form the top main oil passage 2 and the bottom main oil passage of the oil tank 1. The oil outlet 22 and the oil inlet 21 are respectively located on the upper and lower parts of the side wall of the oil tank 1, and are connected to the top main oil passage 2 and the bottom main oil passage respectively.

[0039] Transformer oil 17 enters the oil tank 1 from the bottom oil inlet 21, flows upward through the iron core 19 and winding 18 and absorbs heat. After the density decreases, it naturally rises to the top of the oil tank 1 and collects in the top main oil channel 2. Then it flows from the oil outlet 22 through the radiator return oil pipe into the radiator for cooling and then flows back to the oil tank 1 from the oil inlet 21.

[0040] The above is actually a common configuration for transformers in this embodiment and in the prior art. Compared with the prior art, this embodiment also makes the following improvements:

[0041] like Figure 1 , 2 As shown, the transformer in this embodiment is also equipped with a dielectric barrier discharge plasma device. The dielectric barrier discharge plasma device in this embodiment consists of a plasma control unit 5, an alternating power supply 4, various sensors, and electrode pairs 3.

[0042] Electrode pair 3 includes a high-voltage electrode 11 and a ground electrode 14, which are sealed through the top wall of the oil tank 1 and connected to the alternating power supply 4 via insulated power wires 12. The high-voltage electrode 11 is a needle electrode (in this embodiment, a needle electrode refers to an electrode structure with a discharge tip, not limited to a long, thin, pointed structure), completely encased in a dielectric barrier layer 10. The ground electrode 14 is an arc-shaped plate electrode, connected to the transformer oil tank 1 as a reference ground potential. The needle and plate are arranged vertically opposite each other in the main oil passage 2 at the top of the oil tank 1. Upon startup, a non-equilibrium low-temperature plasma is generated between them, forming an ion wind effect and producing a horizontal velocity component, driving the oil to accelerate towards the oil outlet 22.

[0043] In this embodiment, the arc-shaped plate electrode has two functions. On the one hand, it acts as a flow guide plate to receive hot oil from the transformer winding 18 and the iron core 19 and guide the hot oil to flow in a specified direction. On the other hand, it is paired with the needle electrode to generate non-equilibrium low-temperature plasma and generate a horizontal velocity component to drive the oil to accelerate its flow and circulation.

[0044] In an oil-immersed transformer environment, the flow guide plate is an essential component that guides the hot oil to flow in a designated direction and avoids flow dead zones. In this embodiment, an arc-shaped plate electrode serves a dual function, which can reduce the number of components and the space occupied in the transformer tank.

[0045] In this embodiment, electrode pair 3 can be arranged in more than one pair as needed.

[0046] like Figure 2 As shown, in this embodiment, one end of the arc-shaped plate electrode is the inlet end and the other end is the outlet end. The outlet end points to the oil outlet 22 of the oil tank 1. Both ends are formed by gradually bending downwards from the horizontal. The inlet end has a larger curvature and the needle electrode is set closer to the outlet end to facilitate the flow of oil towards the outlet.

[0047] In this embodiment, the needle electrode is made of tungsten alloy, with a diameter of 2mm and a tip curvature radius of 50μm. The plate electrode is made of stainless steel, with dimensions of 50mm × 30mm × 2mm.

[0048] The dielectric barrier layer 10 is recommended to be an alumina ceramic layer or a polyimide film with a thickness of 0.5 mm or more, or other materials, to ensure that the discharge between the two electrodes is a micro-discharge rather than an arc discharge. Specifically, in this embodiment, the coating layer of the needle electrode is formed by plasma spraying, and the material is alumina ceramic with a purity of 99%, a thickness of 0.5 mm ± 0.05 mm, a dielectric constant of 9.8, and a withstand field strength > 20 kV / mm.

[0049] The sensors used in this embodiment include a temperature sensor array 6, an oil quality monitoring sensor 7, and a flow rate sensor 8. These sensors are connected to the plasma control unit 5 via insulated signal wires 9, which pass through a sealed section on the top wall of the oil tank 1. The plasma control unit 5 uses these sensors to monitor the oil temperature, dissolved gas concentration and dielectric strength, and oil flow rate in real time. The plasma control unit 5 is also connected to an alternating power supply 4 and a redundant circuit breaker 15 via signal wires 9. The redundant circuit breaker 15 is installed in the connection line between the high-voltage electrode 11 and the alternating power supply 4.

[0050] The plasma control unit 5 dynamically adjusts the discharge of electrode pair 3 by controlling the alternating power supply 4 based on oil temperature, oil flow rate, and the concentration of fault-characteristic gases. For example, if the plasma control unit 5 predicts the cooling demand based on the oil temperature, it activates the alternating power supply 4 to apply a high-frequency pulse voltage to electrode pair 3, causing it to generate micro-discharge and form an ion wind, driving hot oil from oil outlet 22 to the radiator for cooling. The flow rate is recommended to be controlled at 0.1-0.5 m / s. Compared to natural oil convection, this can increase the speed by 10%-30%, comparable to using an oil pump. For example, when the plasma control unit 5 detects that the transformer oil temperature exceeds the limit, it gradually increases the power of the alternating power supply 4; when the concentration of fault characteristic gases such as C2H2, C2H4, and CH4 is detected to be >1ppm, the discharge intensity is increased up to 50W to strengthen gas decomposition; when the load is reduced or the oil quality is good, the dielectric barrier discharge plasma device automatically reduces the power or goes into sleep mode to avoid excessive processing and energy consumption; when an abnormality is detected, such as oil temperature >90℃ or oil flow rate >1m / s or oil flow rate <0.05m / s (determined as drive failure), the redundant circuit breaker 15 cuts off the current supplied by the alternating power supply 4 to the electrode pair 3 within <10ms to prevent the fault from expanding and better ensure system safety.

[0051] The alternating power supply 4 outputs high-frequency, high-voltage pulses. In this embodiment, its frequency range is 10-100kHz, pulse width range is 0.1-5μs, voltage amplitude range is 5-15kV, pulse rise time is <50ns, and the average output power is controlled to ≤50W per electrode group. The plasma control unit 5 achieves adaptive matching of output power by dynamically adjusting the pulse width, voltage amplitude, and frequency of the output waveform of the alternating power supply 4.

[0052] In this embodiment, the average power consumption of a single electrode group is ≤50W, and the total energy consumption of the system is only 5%-8% of that of traditional oil pump cooling. The annual power saving can reach tens of thousands of kWh, which greatly reduces the operating cost of the substation and meets the requirements of green power grid energy conservation and consumption reduction.

[0053] The gas collection chamber 16 is located at the top of the oil tank 1 and is connected to the main oil passage 2. It is used to collect the non-condensable gases produced by decomposition and the original (pre-decomposition) gases in the oil. The exhaust valve 20 on it is used for periodic exhaust.

[0054] In this embodiment, the insulated power conductor 12 has a withstand voltage rating of 30kV. The insulated power conductor 12 is sealed to the tank wall with a double sealing ring 13. The inner ring of the double sealing ring 13 is a fluororubber O-ring, and the outer ring is a polytetrafluoroethylene V-ring, which can ensure that the annual leakage rate of the tank is <0.1%.

[0055] This embodiment is an application of Embodiment 1. Based on Embodiment 1, the following design has been optimized:

[0056] 1) The electrode pair structure has been optimized: In this embodiment, the arc plate electrode performs two functions, which reduces the number of components and reduces the space occupied by the transformer tank.

[0057] 2) Intelligentization is achieved: The plasma control unit judges the load change by parameters such as oil temperature, oil quality, and oil flow rate, and realizes adaptive intelligent adjustment of cooling power, which solves the problem of over-cooling or under-cooling caused by the fixed speed operation of mechanical oil pump, and optimizes the transformer operating temperature curve.

[0058] 3) Further enhances system safety: By monitoring anomalies through the plasma control unit and combining redundant circuit breakers for rapid disconnection protection within <10ms, the risk of arc igniting transformer oil can be fundamentally eliminated, thus better ensuring system safety.

[0059] In summary, this invention achieves low power consumption, long lifespan, and intelligent cooling while simultaneously improving the insulation performance and operational safety of transformers. It is particularly suitable for thermal management of transformers in ultra-high voltage, large-capacity, and unattended substations, providing a revolutionary solution for oil-immersed transformer cooling technology. Furthermore, the driving efficiency of this invention's drive scheme is unaffected by changes in oil viscosity with temperature, avoiding the problem of uneven flow rates when dealing with hot and cold oil in traditional oil pumps, resulting in a more stable oil flow rate.

Claims

1. A transformer oil circulation plasma enhancement and purification system, comprising a transformer and an external radiator, wherein the transformer includes an oil tank, and windings and a core are arranged inside the oil tank. The intervals between the windings and the top and bottom of the oil tank are respectively the top main oil passage and the bottom main oil passage. The oil outlet and the oil inlet are respectively located on the upper and lower parts of the side wall of the oil tank. The external radiator is connected to the top main oil passage and the bottom main oil passage through them respectively. Its features are, The enhancement and purification system also includes a dielectric barrier discharge plasma device, which includes an alternating power supply and an electrode pair. The electrode pair includes a high-voltage electrode and a ground electrode, which are respectively connected to the alternating power supply after being sealed through an insulated power wire through the oil tank. The high-voltage electrode is a needle electrode, which is completely wrapped by a dielectric barrier layer. The ground electrode is an arc-shaped plate electrode. The needle and plate electrodes are arranged opposite each other in the top main oil channel. One end of the arc-shaped plate electrode is an inlet end and the other end is an outlet end. Both ends are formed by gradually bending downward from the horizontal, with the inlet end having a greater curvature. The needle electrode is set close to the outlet end. The plate electrode is used to receive hot oil from the transformer windings and core and guide the hot oil to the oil outlet.

2. The enhancement and purification system according to claim 1, characterized in that, The enhancement and purification system also includes a plasma control unit and a sensor for monitoring oil temperature. The sensor is connected to the plasma control unit after passing through the oil tank in an insulated signal wire. The plasma control unit is connected to the alternating power supply. The plasma control unit determines the cooling requirement based on the acquired oil temperature and adjusts the output power of the alternating power supply.

3. The enhancement and purification system according to claim 2, characterized in that, The enhancement and purification system is also equipped with a sensor for monitoring oil quality. This sensor is also connected to the plasma control unit after passing through the oil tank in an insulated signal wire. The plasma control unit adjusts the output power of the alternating power supply based on the fault characteristic gas concentration information obtained through the sensor.

4. The enhancement and purification system according to claim 3, characterized in that, The enhancement and purification system is also equipped with a sensor for monitoring oil flow rate. This sensor is also connected to the plasma control unit after passing through the oil tank in an insulated signal wire. The plasma control unit adjusts the output power of the alternating power supply based on the oil flow rate information obtained through the sensor.

5. The enhancement and purification system according to claim 4, characterized in that, The enhancement and purification system also includes a redundant circuit breaker, which is installed in the connection line between the high-voltage electrode and the alternating power supply. The plasma control unit is connected to the redundant circuit breaker and controls the redundant circuit breaker to disconnect within <10ms when it detects abnormal oil temperature, oil flow rate or fault characteristic gas concentration.

6. The enhancement and purification system according to claim 1, characterized in that, The top of the oil tank is equipped with a gas collection chamber that communicates with its interior, and the gas collection chamber is controlled to release gas through an exhaust valve.

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