A temperature gradient control system for a basin-type insulator based on infrared feedback

Abstract

An infrared feedback-based temperature gradient control system for a basin-type insulator includes a cooling system, a heating system, and a temperature monitoring and control system. The cooling system includes a cooling copper ring and is used to cool the outer area of ​​the basin-type insulator. The heating system includes a central annular heater and is used to uniformly heat the inner edge area of ​​the basin-type insulator in a circumferential direction. The temperature monitoring and control system includes an infrared camera and a control module. The infrared camera monitors the temperature distribution information on the surface of the basin-type insulator, and the control module adjusts the output power of the cooling system and the heating system according to the temperature distribution information on the surface of the basin-type insulator to build and maintain a target temperature gradient of cold periphery and hot center on the basin-type insulator.

Description

Technical Field

[0001] This invention relates to the field of power equipment testing, and in particular to a temperature gradient control system for basin-type insulators based on infrared feedback. Background Technology

[0002] Gas-insulated metal-enclosed switchgear (GIS) has been widely used in power systems due to its advantages such as small footprint, good insulation performance, and high operational reliability, especially suitable for important power transmission and transformation projects in high-altitude, cold, and large temperature difference regions. As a key insulation and support component in GIS, the pot-type insulator undertakes important functions such as conductor support, gas chamber isolation, and gas-solid composite insulation. Its insulation condition directly affects the safe and stable operation of the GIS equipment. For GIS equipment operating in high-altitude and cold regions, the low external ambient temperature, complex operating conditions, and the heating of current-carrying conductors inside the equipment can easily cause significant uneven temperature distribution in the pot-type insulator during operation, resulting in a large temperature gradient that significantly affects its insulation performance and partial discharge characteristics.

[0003] The problems faced by basin-type insulators under large temperature gradients are mainly reflected in the following aspects: On the one hand, low temperature environments and temperature gradients alter the dielectric properties, surface conductivity, and charge migration patterns of insulating gases and solid insulating materials, making charge accumulation and electric field distortion more likely to occur on the surface of the basin-type insulator and at the gas-solid interface. On the other hand, under the combined action of electric and temperature fields, more complex partial discharge activities may occur in local areas of the basin-type insulator, and this discharge process varies significantly between different temperature regions, thereby accelerating insulation aging and increasing the risk of insulation failure. Especially in extremely cold operating environments, the coupling between internal defects of GIS equipment, interface state changes, and non-uniform temperature fields makes the initiation, development, and evolution of partial discharge in basin-type insulators more complex, making it difficult to accurately reflect their actual operating state using conventional test methods under uniform temperature conditions.

[0004] Furthermore, with increasingly stringent environmental protection requirements, using SF6 / N2 mixed gas to replace pure SF6 gas as the insulating medium for GIS has become an important development direction. Compared with pure SF6 gas, SF6 / N2 mixed gas has certain advantages in reducing SF6 usage and mitigating the greenhouse effect, but its insulation performance, discharge characteristics, and response to temperature changes differ significantly from pure SF6 gas. Especially in extremely cold environments, the composition ratio, gas density, dielectric strength, and gas-solid interface electric field distribution of SF6 / N2 mixed gas are jointly affected by low temperature and temperature gradient, resulting in more complex variations in surface charge accumulation, local electric field distortion, and partial discharge activity of basin insulators. Therefore, research on the insulation withstand characteristics of basin insulators under SF6 / N2 mixed gas conditions urgently requires the establishment of a test system capable of simultaneously simulating low temperature, large temperature gradient, and mixed gas insulation environments to more realistically reflect their actual operating conditions.

[0005] Existing testing equipment for the insulation performance of basin-type insulators mostly focuses on withstand voltage tests and partial discharge tests under normal temperature conditions or single low-temperature conditions. It typically only applies cooling to the exterior of the basin-type insulator, making it difficult to simultaneously construct a large temperature gradient—cold at the periphery and hot at the center—that matches actual operating conditions. Furthermore, it is difficult to precisely adjust and maintain this temperature gradient. Especially in high-voltage, confined mixed gas environments, relying solely on external cooling makes it difficult to actively construct the temperature at the hot end of the basin-type insulator's center, leading to a difference between the tested temperature field and the actual operating temperature field of GIS. On the other hand, existing temperature control methods often employ single-point temperature feedback or ambient temperature feedback, which is insufficient to accurately reflect the surface temperature distribution and temperature gradient changes of the basin-type insulator. Because the temperature field of the basin-type insulator has a distinct spatial distribution characteristic, precise control of the temperature gradient cannot be achieved through single-point temperature feedback alone, which is also detrimental to the repeatability and consistency of subsequent insulation withstand tests or partial discharge tests.

[0006] Therefore, there is an urgent need in the existing technology to propose a temperature gradient control system that can accurately construct and stably maintain a large temperature gradient in a basin insulator under SF6 / N2 mixed gas insulation conditions through the synergistic effect of peripheral cooling and central heating, so as to more realistically reflect the actual operating status of GIS basin insulators in cold environments. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention adopts the following solution.

[0008] A temperature gradient control system for a basin-type insulator based on infrared feedback includes a cooling system, a heating system, and a temperature monitoring and control system.

[0009] The cooling system includes a cooling copper ring and is used to cool the outer area of ​​the basin insulator.

[0010] The heating system includes a central annular heater, which is used to uniformly heat the inner edge region of the basin insulator in a circumferential direction.

[0011] The temperature monitoring and control system includes an infrared camera and a control module; wherein:

[0012] The infrared camera is used to monitor the temperature distribution information on the surface of the basin insulator. The control module adjusts the output power of the cooling system and the heating system according to the temperature distribution information on the surface of the basin insulator, so as to build and maintain a target temperature gradient of cold on the periphery and hot in the center on the basin insulator.

[0013] Optionally, the system further includes: a GIS test tank for providing a sealed gas insulation space; the cooling copper ring is disposed outside the GIS test tank and clamped around the basin insulator.

[0014] Optionally, the system further includes a gas mixing control system, connected to the GIS test tank, for mixing SF6 and N2 gases in a set ratio and then filling the GIS test tank.

[0015] Optionally, the refrigeration system further includes a refrigeration unit, wherein the heat-conducting copper ring is connected to the refrigeration unit via a copper braided heat-conducting connector.

[0016] Optionally, the central annular heater is located near the inner edge of the basin insulator and is insulated from the central guide rod; wherein the central guide rod is installed inside the GIS test tank.

[0017] Optionally, the central annular heater is an annular resistance heater, arranged circumferentially along the inner edge of the basin insulator.

[0018] Optionally, the temperature monitoring and control system further includes a temperature sensor for monitoring ambient temperature.

[0019] Optionally, the control module adopts a phased control strategy, and the control module is configured to execute a control process that includes a pre-cooling phase, a gradient establishment phase, and a gradient holding phase.

[0020] Optionally, a cooling control signal is generated first during the precooling stage to reduce the temperature of the outer area of ​​the basin insulator; a cooling control signal and a heating control signal are generated simultaneously during the gradient establishment stage; and fine-tuning is performed according to the temperature gradient deviation during the gradient holding stage.

[0021] A method for controlling the temperature gradient of a basin-type insulator based on infrared feedback includes the following steps:

[0022] Step S1: Install the pot-type insulator to be tested into the GIS test tank, and arrange a central ring heater near its inner edge, clamp a cooling copper ring around it, and arrange an infrared camera and a temperature sensor.

[0023] Step S2: After evacuating the GIS test tank, mix SF6 gas and N2 gas according to a preset ratio and fill the GIS test tank to a preset pressure value.

[0024] Step S3: After the gas is filled, start the cooling system to cool the outer area of ​​the basin insulator through the cooling copper ring; then, start the heating system to heat the inner area of ​​the basin insulator through the central ring heater.

[0025] Step S4: The infrared temperature distribution information of the surface of the basin insulator and the ambient temperature information are collected in real time through the temperature monitoring and control system. The cooling output of the cooling system and the heating output of the heating system are adjusted through closed-loop control to make the basin insulator form a target temperature gradient of cold on the outside and hot in the center.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects:

[0027] (1) The present invention uses the surface temperature distribution of the basin insulator obtained by the infrared camera as the core feedback quantity, and no longer relies on single-point temperature feedback, which can more accurately characterize the actual temperature field and temperature gradient distribution of the basin insulator.

[0028] (2) Through the synergistic effect of peripheral cooling and central heating, the present invention can actively construct a radial temperature gradient of cold periphery and hot center of basin insulator, which is closer to the actual operating temperature field of GIS basin insulator in cold environments.

[0029] (3) The present invention improves the accuracy, stability and repeatability of temperature gradient control by simultaneously adjusting the output of the refrigeration system and the heating system through closed-loop control. Attached Figure Description

[0030] The accompanying drawings illustrate exemplary embodiments of the invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification.

[0031] Figure 1 This is a schematic diagram of a basin-type insulator temperature control system based on infrared feedback in one embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the connection method of the refrigeration system in one embodiment of the present invention;

[0033] Figures 3(a) and 3(b) are schematic diagrams of a cooling copper ring in one embodiment of the present invention;

[0034] Figure 4 This is an infrared thermographic image of a basin-type insulator in one embodiment of the present invention;

[0035] Figure 5 This is a block diagram illustrating the temperature gradient control principle in one embodiment of the present invention;

[0036] Figures 6(a) to 6(c) This is an overall connection diagram of a basin-type insulator temperature control system based on infrared feedback in one embodiment of the present invention;

[0037] Figures 7(a) and 7(b) are curves of peripheral temperature / inner edge temperature / temperature gradient and output of cooling / heating system versus time in one embodiment of the present invention.

[0038] Figure 8 This is a temperature distribution diagram during the stable phase in one embodiment of the present invention. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The technical solution of this invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] Unless otherwise stated, the exemplary embodiments / exemplifications shown are to be understood as providing exemplary features of various details that provide ways in which the technical concept of the invention can be implemented in practice. Therefore, unless otherwise stated, the features of the various embodiments / exemplifications may be additionally combined, separated, interchanged and / or rearranged without departing from the technical concept of the invention.

[0042] The use of crosshairs and / or shading in the accompanying drawings is generally used to clarify the boundaries between adjacent components. Thus, unless otherwise stated, the presence or absence of crosshairs or shading does not convey or indicate any preference or requirement for the specific material, material properties, dimensions, proportions, commonalities between the illustrated components, or any other characteristics, properties, etc., of the components. Furthermore, in the accompanying drawings, the dimensions and relative dimensions of components may be exaggerated for clarity and / or descriptive purposes. When exemplary embodiments can be implemented differently, a specific process sequence may be performed in a different order than that described. For example, two consecutively described processes may be performed substantially simultaneously or in the reverse order of their description. Furthermore, the same reference numerals denote the same components.

[0043] When a component is referred to as being "on" or "above" another component, "connected to," or "joined to" another component, the component may be directly on, directly connected to, or directly joined to the other component, or there may be intermediate components. However, when a component is referred to as being "directly on" another component, "directly connected to," or "directly joined to" another component, there are no intermediate components. Therefore, the term "connection" can refer to a physical connection, an electrical connection, etc., and may or may not have intermediate components.

[0044] For descriptive purposes, the present invention may use spatial relative terms such as “below,” “under,” “below,” “down,” “above,” “above,” “higher,” and “side (e.g., in a “sidewall”)” to describe the relationship between one component and another component as shown in the accompanying drawings. In addition to the orientations depicted in the drawings, the spatial relative terms are also intended to encompass different orientations of the device during use, operation, and / or manufacture. For example, if the device in the drawings is flipped, a component described as “below” or “under” another component or feature would subsequently be positioned “above” said other component or feature. Thus, the exemplary term “below” can encompass both “above” and “below” orientations. Furthermore, the device may be otherwise positioned (e.g., rotated 90 degrees or in other orientations), thus interpreting the spatial relative descriptive terms used herein accordingly.

[0045] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, unless the context clearly indicates otherwise, the singular forms “a” and “the” are intended to include the plural forms as well. Furthermore, when the terms “comprising” and / or “including” and variations thereof are used in this specification, it indicates the presence of the stated features, integrals, steps, operations, parts, components, and / or groups thereof, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, parts, components, and / or groups thereof. It should also be noted that, as used herein, the terms “substantially,” “about,” and other similar terms are used as approximate terms rather than as terms of degree, thus explaining the inherent biases in measurements, calculated values, and / or provided values ​​that would be recognized by one of ordinary skill in the art.

[0046] In one embodiment, the present invention provides a temperature gradient control system for a basin-type insulator based on infrared feedback, including a cooling system, a heating system, and a temperature monitoring and control system.

[0047] The cooling system includes a cooling copper ring and is used to cool the outer area of ​​the basin insulator.

[0048] The heating system includes a central annular heater, which is used to uniformly heat the inner edge region of the basin insulator in a circumferential direction.

[0049] The temperature monitoring and control system includes an infrared camera and a control module; wherein:

[0050] The infrared camera is used to monitor the temperature distribution information on the surface of the basin insulator. The control module adjusts the output power of the cooling system and the heating system according to the temperature distribution information on the surface of the basin insulator, so as to build and maintain a target temperature gradient of cold on the periphery and hot in the center on the basin insulator.

[0051] Optionally, the system further includes: a GIS test tank for providing a sealed gas insulation space; the cooling copper ring is disposed outside the GIS test tank and clamped around the basin insulator.

[0052] Optionally, the system further includes a gas mixing control system, connected to the GIS test tank, for mixing SF6 and N2 gases in a set ratio and then filling the GIS test tank.

[0053] Optionally, the refrigeration system further includes a refrigeration unit, wherein the heat-conducting copper ring is connected to the refrigeration unit via a copper braided heat-conducting connector.

[0054] Optionally, the central annular heater is located near the inner edge of the basin insulator and is insulated from the central guide rod; wherein the central guide rod is installed inside the GIS test tank.

[0055] Optionally, the central annular heater is an annular resistance heater, arranged circumferentially along the inner edge of the basin insulator.

[0056] Optionally, the temperature monitoring and control system further includes a temperature sensor for monitoring ambient temperature.

[0057] Optionally, the control module adopts a phased control strategy, and the control module is configured to execute a control process that includes a pre-cooling phase, a gradient establishment phase, and a gradient holding phase.

[0058] Optionally, a cooling control signal is generated first during the precooling stage to reduce the temperature of the outer area of ​​the basin insulator; a cooling control signal and a heating control signal are generated simultaneously during the gradient establishment stage; and fine-tuning is performed according to the temperature gradient deviation during the gradient holding stage.

[0059] In another embodiment, the present invention proposes a temperature gradient control system for a basin-type insulator based on infrared feedback, which includes a refrigeration system, a heating system, a temperature monitoring and control system, a GIS test tank, and a gas mixing control system; wherein:

[0060] The refrigeration system is used to cool the outer area of ​​the basin insulator. The refrigeration system includes a chiller, a compressor, a metal hose, a refrigeration unit, and a cooling copper ring. The cooling copper ring is set outside the GIS test tank and clamped around the basin insulator to implement directional cooling of the outer edge area of ​​the basin insulator.

[0061] The compressor compresses low-pressure helium gas into high-pressure helium gas. The chiller supplies water to the compressor, cooling the high-pressure helium gas. The cooled high-pressure helium gas then enters the refrigerator through a metal hose, where it undergoes adiabatic expansion to achieve a low temperature. Figure 2As shown in Figures 3(a) and 3(b), the refrigeration unit is connected to the cooling copper ring via a copper braided cooling connector. Figure 3(a) shows the structure of the cooling copper ring and the copper braided cooling connector. The cooling copper ring is a two-open semi-circular clamping structure, which is bolted together and installed on the outside of the GIS test tank and clamped around the basin-type insulator. The copper braided cooling connector includes a first copper connector located at the cold end of the refrigeration unit, a second copper connector located on one side of the cooling copper ring, and a multi-strand copper wire connecting the two. The first copper connector and / or the second copper connector are composed of a copper plug and a copper disc. The copper plug and the copper disc are respectively machined with multiple through holes distributed along concentric circles. The two ends of the multi-strand copper wire are inserted into the corresponding through holes and fixed, so that the multi-strand copper wire and the copper plug and copper disc form a flexible, highly thermally conductive connection structure. The copper connector features a corresponding upper and lower mating structure on some of its connecting surfaces. A clamping and locking mechanism ensures reliable contact between the copper stranded wire ends and the copper connector, reducing contact thermal resistance and improving cold energy transfer efficiency. Figure 3(b) illustrates the physical connection between the cooling copper ring, the copper braided cooling connector, and the refrigerator. One end of the copper braided cooling connector is connected to the cold end of the refrigerator, and the other end is connected to the cooling copper ring. This allows the low temperature generated by the refrigerator to be transferred via the copper connector and multiple copper strands to the cooling copper ring, and then from the cooling copper ring to the outer area of ​​the basin insulator, achieving external directional cooling of the basin insulator.

[0062] The heating system is a central annular heater located near the inner edge of the basin insulator. It is used to heat the central inner edge area of ​​the basin insulator. The central annular heater is insulated from the central guide rod and is used to uniformly heat the inner edge area of ​​the basin insulator in a circumferential manner, thereby forming a central hot end.

[0063] The temperature monitoring and control system uses an infrared camera located at the observation window of the GIS test tank to monitor the temperature and gradient distribution of the basin insulator. Combined with the ambient temperature monitored by the temperature sensor, the acquired temperature and temperature gradient information is fed back to the control unit to adjust the output power of the cooling system and the heating system respectively. This allows the cooling copper ring and the central ring heater to work together to create a target temperature gradient of cold periphery and hot center on the basin insulator.

[0064] The GIS test tank is used to provide a sealed gas insulation space to simulate the actual operating conditions of the basin insulator; the gas mixing control system is used to accurately mix SF6 and N2 gases in a certain proportion after vacuuming, and then introduce the mixed gas into the GIS test tank.

[0065] The temperature monitoring and control system includes an infrared camera, a temperature sensor, a PID closed-loop control module, and a zero-crossing comparator. The infrared camera is used to monitor the surface temperature distribution of the basin insulator, such as... Figure 4As shown. The temperature sensor is used to monitor the ambient temperature.

[0066] It should be noted that the observation window of the GIS test tank is made of fused silica glass, with a high transmittance range from near-infrared (approximately 0.78 μm) to approximately 3.5 μm. Furthermore, SF6 gas exhibits a strong absorption band around approximately 10.55 μm, while commonly used infrared cameras operate in the 8–14 μm band. The absorption properties of the observation window and SF6 significantly affect temperature measurements; therefore, corrections are needed for the temperature measured by the infrared camera. The radiation signal received by the infrared camera can be expressed as:

[0067]

[0068] In the formula: τ w τ represents the equivalent transmittance of the observation window within the imaging band. g ε is the equivalent transmittance of the SF6 / N2 gas mixture under imaging band, pressure, temperature, and optical path conditions, and L is the surface emissivity of the basin insulator. b (•) is the blackbody radiation function, T obj T represents the actual surface temperature of the basin-type insulator. ref For the equivalent temperature of environmental reflection, T path This is the equivalent background temperature for the window and gas path.

[0069] The above formula can be written as:

[0070]

[0071] The corrected true surface temperature is:

[0072]

[0073] The temperature control strategy of the temperature monitoring and control system is as follows:

[0074] The corrected average temperature T of the outer region of the basin insulator, measured by an infrared camera. o and the average temperature T of the inner edge region i As a characteristic parameter of the temperature field, the average temperature gradient from the outside to the inside of the basin insulator is defined as:

[0075]

[0076] In the formula: L is the equivalent radial distance between the outer and inner characteristic positions of the basin insulator.

[0077] Let the target temperature of the outer region of the basin-type insulator be T. o * The target temperature gradient is G. * Then, the external temperature deviation and the temperature gradient deviation are defined as follows:

[0078]

[0079] The temperature monitoring and control system is based on the external temperature deviation e T degree deviation e G Do not adjust the output of the cooling system u c System output u h .

[0080] Refrigeration system output u c satisfy:

[0081]

[0082] In the formula: k represents the sequence number of the discrete control time, K pc K ic K dc These are the proportional, integral, and derivative control coefficients of the refrigeration system, K. gc This is the temperature gradient compensation coefficient. To control the sampling period.

[0083] Heating system output u h satisfy:

[0084]

[0085] In the formula: k represents the sequence number of the discrete control time, K ph K ih K dh These are the proportional, integral, and derivative control coefficients of the refrigeration system. To control the sampling period.

[0086] like Figure 5 As shown, the temperature monitoring and control system includes a pre-cooling stage, a gradient establishment stage, and a gradient holding stage. In the pre-cooling stage, the temperature of the outer area of ​​the basin insulator is preferentially reduced. In the gradient establishment stage, the outputs of the cooling and heating systems are adjusted synchronously. In the gradient holding stage, fine adjustments are made based on the outer temperature deviation and the temperature gradient deviation. When the following conditions are met:

[0087]

[0088] And the duration of satisfying this condition reaches t. s When the temperature field of the basin insulator reaches a stable state, a partial discharge test can be conducted.

[0089] In another embodiment, the present invention provides a method for controlling the temperature gradient of a basin-type insulator based on infrared feedback, comprising the following steps:

[0090] Step S1: Install the pot-type insulator to be tested into the GIS test tank, and arrange a central ring heater near its inner edge, clamp a cooling copper ring around it, and arrange an infrared camera and a temperature sensor.

[0091] Step S2: After evacuating the GIS test tank, mix SF6 gas and N2 gas according to a preset ratio and fill the GIS test tank to a preset pressure value.

[0092] Step S3: After the gas is filled, start the cooling system to cool the outer area of ​​the basin insulator through the cooling copper ring; then, start the heating system to heat the inner area of ​​the basin insulator through the central ring heater.

[0093] Step S4: The infrared temperature distribution information of the surface of the basin insulator and the ambient temperature information are collected in real time through the temperature monitoring and control system. The cooling output of the cooling system and the heating output of the heating system are adjusted through closed-loop control to make the basin insulator form a target temperature gradient of cold on the outside and hot in the center.

[0094] In another embodiment, the present invention provides a temperature gradient control system for a basin-type insulator based on infrared feedback. This system simulates the SF6 / N2 mixed gas insulation conditions inside GIS equipment in extremely cold environments, constructing a radial temperature gradient with a cold periphery and a hot center for the basin-type insulator, and performing precise closed-loop control on this temperature gradient. The control system as a whole includes a refrigeration system, a heating system, a temperature monitoring and control system, a GIS test tank, and a gas mixing control system. The extremely cold environments in this embodiment, and in the field of power equipment condition monitoring, refer to a temperature distribution with a temperature gradient where the periphery of the tank is low (due to low ambient temperature) while the central guide rod is hot (due to heat generated by a large current). This embodiment quantifies this temperature gradient.

[0095] The refrigeration system is used to cool the outer area of ​​the basin-type insulator. The refrigeration system includes a chiller, a compressor, a metal hose, a refrigeration unit, and a cooling copper ring. The chiller, compressor, metal hose, and refrigeration unit form a refrigeration circuit, and the cooling copper ring is connected to this circuit. The cooling copper ring is an open-type annular clamping structure, connected to the refrigeration unit via a flexible cooling connector, and clamped to the outer periphery of the basin-type insulator from outside the GIS test tank. The cooling copper ring transfers the cold energy generated by the refrigeration system to the outer area of ​​the basin-type insulator, thus forming the outer cold end of the basin-type insulator.

[0096] The heating system is used to heat the inner edge region of the basin insulator. The heating system is a central annular heater, preferably an annular resistance heater, located near the inner edge of the basin insulator. The central annular heater is arranged circumferentially along the inner edge of the basin insulator and is insulated from the central guide rod, used to uniformly heat the inner edge region of the basin insulator in a circumferential manner, thereby forming the central hot end of the basin insulator.

[0097] The temperature monitoring and control system uses an infrared camera and temperature sensors to monitor the temperature field of the basin insulator, and adjusts the outputs of the cooling and heating systems separately through PID closed-loop control. The infrared camera acquires infrared thermal images of the basin insulator surface, and extracts the average temperature Ta of the outer region of the basin insulator based on the infrared thermal images. o and the average temperature T of the inner edge region i Temperature sensors are used to assist in monitoring ambient temperature.

[0098] In this embodiment, the average temperature gradient of the basin-type insulator from the outside to the inside is defined as:

[0099]

[0100] In the formula: L is the equivalent radial distance between the outer and inner characteristic positions of the basin insulator.

[0101] Let the target temperature of the outer region of the basin-type insulator be T. o * The target temperature gradient is G. * Then, the external temperature deviation and the temperature gradient deviation are defined as follows:

[0102]

[0103] The temperature monitoring and control system is based on the external temperature deviation e T degree deviation e G Do not adjust the output of the cooling system u c System output u h .

[0104] Refrigeration system output u c satisfy:

[0105]

[0106] In the formula: k represents the sequence number of the discrete control time, K pc K ic K dc These are the proportional, integral, and derivative control coefficients of the refrigeration system, K. gc This is the temperature gradient compensation coefficient. To control the sampling period.

[0107] Heating system output u h satisfy:

[0108]

[0109] In the formula: k represents the sequence number of the discrete control time, K ph K ih K dh These are the proportional, integral, and derivative control coefficients of the refrigeration system, respectively, and Δt is the control sampling period.

[0110] The temperature monitoring and control system includes a pre-cooling stage, a gradient establishment stage, and a gradient holding stage. During the pre-cooling stage, the temperature of the outer area of ​​the basin insulator is preferentially reduced. During the gradient establishment stage, the outputs of the cooling and heating systems are adjusted synchronously. During the gradient holding stage, fine adjustments are made based on the external temperature deviation and the temperature gradient deviation. When the following conditions are met:

[0111]

[0112] And the duration of satisfying this condition reaches t. s When the temperature field of the basin insulator reaches a stable state, a partial discharge test can be conducted.

[0113] The GIS test tank provides a sealed gas-insulated space to simulate the actual operating conditions of a basin insulator. The basin insulator to be tested and its central guide rod are installed inside the GIS test tank, and the tank meets the sealing and pressure resistance requirements under SF6 / N2 mixed gas insulation conditions.

[0114] The gas mixing control system is used to precisely mix SF6 and N2 gases in a certain proportion, and then introduce the mixed SF6 / N2 gas into the GIS test tank to construct the mixed gas environment required for the temperature gradient control of the basin insulator.

[0115] When the control system of this invention is running, it includes:

[0116] First, the pot-type insulator to be tested is installed inside the GIS test tank, and the central guide rod, central annular heater, cooling copper ring, infrared camera, and temperature sensor are arranged and connected. The actual overall system connection is as follows. Figures 6(a) to 6(c)As shown in Figure 6(a), the GIS test tank with the central guide rod, basin insulator, central annular heater, and temperature sensor installed is shown in Figure 6(b). Figure 6(b) shows the connection between the refrigerator, the cooling copper ring, and the GIS test tank. The refrigerator is connected to the cooling copper ring through a copper braided cooling connector. The cooling copper ring is located outside the GIS test tank and clamped around the basin insulator. Figure 6(c) shows the observation window where the infrared camera is placed. When implementing temperature gradient control, the infrared camera is placed here to measure and control the surface temperature gradient of the basin insulator.

[0117] Subsequently, the gas mixing control system is connected to the GIS test tank. Before the test begins, the GIS test tank is evacuated, and then SF6 and N2 gases are mixed in a 3:7 ratio using the gas mixing control system and injected into the GIS test tank until the preset pressure value of 0.4 MPa is reached. Through this gas mixing control system, an SF6 / N2 mixed gas insulation environment compatible with environmentally friendly GIS equipment in cold regions can be constructed, thereby improving the consistency between test results and actual operating conditions.

[0118] After the gas filling is completed, the pre-cooling stage begins. The refrigeration system is activated, using a chiller, compressor, metal hoses, refrigeration unit, and cooling copper rings to cool the basin-type insulator. When the temperature of the surrounding area reaches T... o Target temperature T near the outer perimeter o * At this point, the gradient establishment phase begins, and the heating system is activated to heat the inner edge area of ​​the basin insulator via a central annular heater. The temperature monitoring and control system collects real-time infrared temperature distribution information from the surface of the basin insulator and ambient temperature information, and adjusts the cooling and heating outputs through closed-loop control to create a target temperature gradient where the basin insulator is cold on the periphery and hot in the center. When both the peripheral temperature and the temperature gradient meet the set error range and the duration reaches t... s At this point, the gradient preservation phase begins.

[0119] In this embodiment, the equivalent radial distance L between the peripheral characteristic position and the inner characteristic position of the basin insulator is 12.0 cm, and the target peripheral temperature is set to T. o * =-25.0℃, target temperature gradient set to G * =4.0℃ / cm, then the inner edge temperature of the target is:

[0120]

[0121] The sampling period Δt is set to 1 second. The temperature monitoring and control system adopts a phased control method, including a pre-cooling phase, a gradient establishment phase, and a gradient holding phase. The allowable error for the ambient temperature is set to... The allowable error for the temperature gradient is taken as The stable holding time is taken as t s =600s.

[0122] When the control system is running as described above, the data during the control process in this embodiment are shown in Table 1. It should be noted that the output quantity uc of the refrigeration system in Table 1 is expressed as a percentage, which represents the relative control command output by the temperature monitoring and control system to the refrigeration system. 100% indicates that the refrigeration system is in the maximum output power state, and 0% indicates that the refrigeration system is off. That is, the u... c This is used only to characterize the control intensity of the refrigeration system, and is not the electrical input power of the compressor unit, nor is it the directly measured physical cooling capacity. The u... h This refers to the output power of the heating system.

[0123] Table 1. Data from the control process in this embodiment.

[0124]

[0125] As shown in Table 1, during the pre-cooling phase (0–20 min), the refrigeration system is prioritized for operation, and the temperature T in the surrounding area is [high / low]. o The temperature drops rapidly, while the temperature T in the inner region decreases. i The temperature decreases passively only as the overall temperature field changes; after about 20 minutes, when the temperature of the outer area approaches the target outer temperature, the heating system starts and enters the gradient establishment stage, and the temperature of the inner edge area of ​​the basin insulator gradually rises, thereby establishing a radial temperature gradient with a cold outer periphery and a hot center; after 50 to 60 minutes, both the outer temperature and the temperature gradient enter the vicinity of the target value, and the system enters the gradient maintenance stage.

[0126] Based on the data in Table 1, the control process curves were plotted, as shown in Figures 7(a) and 7(b). Figure 7(a) shows the external temperature / internal temperature / temperature gradient-time curve; Figure 7(b) shows the output-time curve of the cooling / heating system.

[0127] Based on Figures 7(a) and 7(b), the following conclusions can be drawn:

[0128] 1) The temperature-time curve of the outer area shows that the temperature T in the outer area... o It started at 18.6℃ and continued to decrease, reaching the target temperature after about 35 to 40 minutes, and then stabilizing at around -25℃ after 50 minutes.

[0129] 2) The inner edge temperature-time curve shows that during the pre-cooling stage, the temperature T in the inner edge region... i It decreases as the overall temperature field changes, gradually rises after the heating system is started, and eventually stabilizes at around 23℃;

[0130] 3) The temperature gradient-time curve shows that the temperature gradient G gradually increases during the precooling stage, and after further correction after the heating system is started, it finally stabilizes at around 4.0℃ / cm.

[0131] 4) The output-time curve of the cooling / heating system shows that the output of the cooling system gradually increases during the pre-cooling stage and moderately decreases after reaching the target ambient temperature; the heating output is activated and gradually increases during the gradient establishment stage, and remains at about 62W during the stable stage.

[0132] The control results of the stable phase in this embodiment are shown in Table 2 and... Figure 8 As shown.

[0133] Table 2 shows the control results during the stable phase of this embodiment (60–90 min).

[0134]

[0135] As shown in Table 2, the system described in this invention can stably control the temperature of the outer region of the basin insulator at around -25℃ under SF6 / N2 mixed gas insulation conditions, and simultaneously stably control the average temperature gradient of the basin insulator from the outside to the inside at around 4.0℃ / cm. This indicates that the present invention can achieve the accurate construction and stable maintenance of the target temperature field of cold outer periphery and hot center.

[0136] To further illustrate the technical effects of the present invention, a comparative example is provided, under the same gas conditions, the same target peripheral temperature, and the same target temperature gradient, using a method that does not introduce infrared temperature gradient feedback and only controls based on the temperature of a single peripheral point. In this comparative example, a pre-cooling stage is still retained, and the heating system is activated after the peripheral area temperature approaches the target value; however, the control system does not extract T from the infrared image. o T i Closed-loop correction is performed with G, and the central ring heater operates at a fixed output of 50W.

[0137] Table 3 shows the steady-state results of the comparative examples (60–90 min).

[0138]

[0139] As shown in Table 3, without infrared feedback for closed-loop temperature gradient control, although the temperature in the outer region can be controlled near the target value, the temperature in the inner region fluctuates significantly. This results in a large deviation between the actual temperature gradient of the basin insulator and the target value, leading to poor stability and difficulty in maintaining the target temperature field for a long time. Comparing this embodiment with the comparative example, it can be seen that this invention acquires the surface temperature distribution of the basin insulator using an infrared camera and feeds back the outer and inner region temperatures extracted from the infrared images to the temperature monitoring and control system. While retaining the pre-cooling stage, it adjusts the output of the cooling system and the heating system respectively, thereby enabling more accurate control of the outer temperature and temperature gradient, achieving higher stability and repeatability of the basin insulator's temperature field.

[0140] Compared to existing technologies that rely solely on a single cold (heat) source outside the GIS test tank to cool (heat) the tank, adjusting power based on the temperature gradient, and passively adjusting based on existing temperature changes to create a natural temperature gradient through cooling (heating) at a single location, this patent presents a dual-actuator structure with the "cold end" and "hot end" physically separated.

[0141] Compared to existing technologies that use artificial climate chambers to achieve low external temperatures for GIS test tanks and apply high currents to the central guide rods of the GIS test tanks to achieve high central temperatures, although there are two cold (heat) sources, active control of the temperature gradient is not achieved. Instead, the temperature gradient is observed and recorded as a response result under different external temperatures and currents. Moreover, this method places extremely high demands on test conditions (artificial climate chambers, large-capacity transformers), leading to a sharp increase in costs.

[0142] This patent utilizes an outer cooling copper ring to form the cold end and an inner central annular heater to form the hot end. These two independent and controllable cold (heat) sources can actively and directionally construct a radial temperature gradient with clear spatial orientation on the basin-type insulator, thereby achieving true closed-loop temperature field control. Furthermore, this patent eliminates the need for artificial climate chambers and large-capacity transformers, significantly reducing testing conditions and cost requirements.

[0143] In summary, the present invention has the following beneficial technical effects:

[0144] 1. Ability to achieve visualized monitoring and precise control of the temperature field of basin-type insulators based on infrared feedback: This invention acquires real-time surface temperature distribution information of basin-type insulators using an infrared camera and feeds back the infrared-detected temperature and temperature gradient information to the temperature monitoring and control system. Compared with control methods that rely solely on single-point temperature sensors, this method can more accurately reflect the overall temperature field distribution characteristics of the basin-type insulator. Based on this infrared feedback information, the temperature monitoring and control system can perform closed-loop regulation of the cooling and heating systems, thereby improving the accuracy, stability, and repeatability of the temperature gradient control of the basin-type insulator.

[0145] 2. This invention can actively construct a target temperature gradient of cold outer periphery and hot center for the basin-type insulator, more closely resembling actual operating conditions: The invention uses a cooling copper ring positioned around the basin-type insulator to provide directional cooling to the outer edge region, and a central annular heater positioned near the inner edge to provide uniform circumferential heating to the inner edge region. This allows the cooling and heating systems to work synergistically, actively constructing a temperature gradient that gradually increases from the outside to the inside of the basin-type insulator. Compared to existing temperature control methods that only use single external cooling, this invention can simultaneously regulate both the cold and hot ends, which is more conducive to simulating the actual temperature distribution of GIS basin-type insulators in extremely cold environments.

[0146] 3. Capable of stably maintaining the target temperature gradient under SF6 / N2 mixed gas insulation conditions, providing a reliable temperature boundary for subsequent operational status studies: This invention organically combines a refrigeration system, a heating system, a temperature monitoring and control system, a GIS test tank, and a gas mixing control system to construct and stably maintain the target temperature gradient of the basin insulator in an SF6 / N2 mixed gas insulation environment. Through phased control of the pre-cooling stage, gradient establishment stage, and gradient maintenance stage, this invention enables the basin insulator to maintain a stable state after reaching the target peripheral temperature and target temperature gradient, thus providing reliable and repeatable experimental conditions for temperature field research and related operational status analysis of basin insulators in high-altitude and cold environments.

[0147] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0148] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0149] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A temperature gradient control system for a pot-type insulator based on infrared feedback, characterized by, This includes refrigeration systems, heating systems, and temperature monitoring and control systems; The cooling system includes a cooling copper ring and is used to cool the outer area of ​​the basin insulator. The heating system includes a central annular heater, which is used to uniformly heat the inner edge region of the basin insulator in a circumferential direction. The temperature monitoring and control system includes an infrared camera and a control module; wherein: The infrared camera is used to monitor the temperature distribution information on the surface of the basin insulator. The control module adjusts the output power of the cooling system and the heating system according to the temperature distribution information on the surface of the basin insulator, so as to build and maintain a target temperature gradient of cold on the periphery and hot in the center on the basin insulator.

2. The system of claim 1, wherein, The system also includes: a GIS test tank for providing a sealed gas insulation space; and a cooling copper ring disposed outside the GIS test tank and clamped around the basin insulator.

3. The system according to claim 2, characterized in that, The system also includes a gas mixing control system, which is connected to the GIS test tank and is used to mix SF6 and N2 gases in a set ratio and then fill the GIS test tank.

4. The system according to claim 1, characterized in that, The refrigeration system also includes a refrigeration unit, and the heat-conducting copper ring is connected to the refrigeration unit through a copper braided heat-conducting connector.

5. The system according to claim 2, characterized in that, The central annular heater is located near the inner edge of the basin insulator and is insulated from the central guide rod; wherein the central guide rod is installed inside the GIS test tank.

6. The system according to claim 5, characterized in that, The central annular heater is an annular resistance heater, arranged circumferentially along the inner edge of the basin insulator.

7. The system according to claim 1, characterized in that, The temperature monitoring and control system also includes a temperature sensor for monitoring ambient temperature.

8. The system according to claim 1, characterized in that, The control module adopts a phased control strategy and is configured to execute a control process that includes a pre-cooling phase, a gradient establishment phase, and a gradient holding phase.

9. The system according to claim 8, characterized in that, During the precooling stage, a cooling control signal is generated first to reduce the temperature of the outer area of ​​the basin insulator; during the gradient establishment stage, cooling control signals and heating control signals are generated simultaneously; and during the gradient holding stage, fine adjustments are made based on the temperature gradient deviation.

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