Intelligent temperature control device for transformer insulating oil

Abstract

The invention discloses an intelligent temperature control device for transformer insulating oil. The intelligent temperature control device comprises a heat preservation shell and a first temperature sensor. A controller, a second temperature sensor and N flexible heating sheets are arranged in the heat preservation shell, the temperature of transformer insulating oil is obtained through the first temperature sensor, and the temperature of the flexible heating sheets is obtained through the second temperature sensor; the N flexible heating sheets are controlled to be opened or closed according to the temperature of the insulating oil and the temperature of the flexible heating sheets; compared with the prior art, the technical scheme is easy to operate, the temperature of the transformer insulating oil can be increased to the set temperature within a short time, and the method is suitable for the low-temperature environment of the alpine region.

Description

Technical Field

[0001] The invention relates to the field of power transformers, and in particular to an intelligent temperature control device for transformer insulating oil. Background Art

[0002] As the scale of my country's power grid continues to expand, when conducting transformer maintenance or testing in cold areas, the problem of low transformer insulating oil temperature is faced, which brings great inconvenience to on-site operations. The relevant safety regulations stipulate that when the transformer oil temperature is lower than 5°C, it is not appropriate to conduct transformer insulation tests. If the test is required, the transformer should be heated (such as oil heat circulation, etc.); other regulations indicate that when conducting various tests related to temperature and humidity (such as measuring DC resistance, insulation dielectric loss factor, leakage current, etc.), the temperature of the test object and the temperature and humidity of the surrounding air should be measured at the same time. When conducting insulation tests, the temperature of the test object should not be lower than 5°C, and outdoor tests should be conducted in good weather, and the relative humidity of the air is generally not higher than 80%. According to relevant regulations, the method of adding a hot oil circulation system is currently used when heating transformers in low-temperature environments in cold areas, that is, the insulating oil in the transformer is extracted for heating, and then the hot oil is circulated back into the transformer. However, this hot oil circulation system has some shortcomings. First, it is necessary to add a heating circulation device and connect it at the oil drain valve and the oil filling valve, which makes the equipment operation complicated. If the operation process is not done properly, the water content of the transformer oil may increase or impurities may be introduced, thus affecting the insulation performance of the transformer. Secondly, the hot oil circulation system needs to reach an insulating oil circulation flow of 10,000 L / h, so the heating power is higher than 140 kW, and the load is relatively high. This not only consumes a lot of energy, but also leads to a longer overall heating time, affecting the efficiency of maintenance or testing. Finally, the equipment is large in size, inconvenient to carry, and has a high transportation cost. This greatly increases the difficulty and cost for maintenance or testing in different locations.

[0003] In summary, although the method of heating the insulating oil in the transformer through the hot oil circulation system has solved the problem of low oil temperature of the transformer insulating oil in cold areas to a certain extent, there are still problems such as complex equipment operation, long heating time, large size and inconvenient transportation, which need further improvement and optimization. Summary of the invention

[0004] In order to solve the problems of complicated operation and long heating time of the insulating oil heating system in the transformer in the prior art, an intelligent temperature control device for the insulating oil of the transformer is proposed;

[0005] An intelligent temperature control device for transformer insulating oil, comprising: a heat-insulating shell and a first temperature sensor;

[0006] A controller, a second temperature sensor and N flexible heating plates are arranged in the thermal insulation shell. A plug-in interface is arranged on the side of each flexible heating plate, and every two adjacent heating plates are connected through the plug-in interface; the flexible heating plate is used to increase the temperature after power is turned on; the first temperature sensor is used to obtain the insulating oil temperature and send the insulating oil temperature to the controller; the second temperature sensor is used to obtain the flexible heating plate temperature and send the flexible heating plate temperature to the controller, and the controller is used to control the N flexible heating plates to be turned on or off according to the received insulating oil temperature and the flexible heating plate temperature.

[0007] Beneficial Effects

[0008] The present application discloses an intelligent temperature control device for transformer insulating oil, comprising a heat-insulating shell and a first temperature sensor; a controller, a second temperature sensor and N flexible heating sheets are arranged in the heat-insulating shell, the temperature of the transformer insulating oil is obtained by the first temperature sensor, and the temperature of the flexible heating sheet is obtained by the second temperature sensor; and the N flexible heating sheets are controlled to be turned on or off according to the temperature of the insulating oil and the temperature of the flexible heating sheet; compared with the prior art, the technical solution of the present application is simple to operate, can raise the transformer insulating oil to a set temperature in a relatively short time, and is suitable for low-temperature environments in high-cold areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of the heating module structure of a specific implementation method of this application;

[0010] Figure 2 This is a schematic diagram of the main part of the transformer according to a specific implementation method of the present application;

[0011] Figure 3 This is a structural diagram of an expansion tooling for a specific implementation of this application;

[0012] Among them, 1 is a transformer, 2 is a transformer core winding, 3 is a thermal insulation shell, 4 is a controller, 5 is a first temperature sensor, 6 is a second temperature sensor, 7 is a flexible heating plate, 8 is a plug-in interface, 9 is a fixed plate, 10 is a movable plate, 11 is a bolt, and 12 is a nut. DETAILED DESCRIPTION

[0013] The following will be combined Figures 1 to 3 , describing the present embodiment, an intelligent temperature control device for transformer insulating oil, comprising: a heat-insulating housing and a first temperature sensor;

[0014] A controller, a second temperature sensor and N flexible heating plates are arranged in the thermal insulation shell. A plug-in interface is arranged on the side of each flexible heating plate, and every two adjacent heating plates are connected through the plug-in interface; the flexible heating plate is used to increase the temperature after power is turned on; the first temperature sensor is used to obtain the insulating oil temperature and send the insulating oil temperature to the controller; the second temperature sensor is used to obtain the flexible heating plate temperature and send the flexible heating plate temperature to the controller, and the controller is used to control the N flexible heating plates to be turned on or off according to the received insulating oil temperature and the flexible heating plate temperature.

[0015] Specifically, the modeling and simulation analysis is carried out by taking the 220kV transformer of Taikai, model SPZ18-220000 / 220, as an example;

[0016] The outer side of the transformer is a shell made of Q235 material with a thickness of 8mm; multiple groups of iron core windings are distributed inside at intervals, and the outer side of the iron core winding and the inner side of the shell are filled with insulating oil. The insulating oil fills the gaps between the various parts of the transformer. The total weight of the insulating oil inside the transformer is about 23,700kg, and the thermal conductivity coefficient is 0.128W / mK.

[0017] The simulation software uses the Fluent simulation analysis software in Ansys to perform modeling and simulation analysis. In order to numerically simulate the heat exchange state in the transformer, the following basic assumptions are made:

[0018] (1) The liquid flows in a three-dimensional stable state;

[0019] (2) Observe the effect of temperature changes on flow and solid boundaries;

[0020] (3) Ignore some external contact heat dissipation space;

[0021] (4) Assume that the heating device stops when the internal liquid is 5°C.

[0022] Setting boundary conditions for the simulation model, including: simulating the external environment temperature setting, opening the thermal energy equation, setting the transformer oil fluid viscosity equation, and defining material properties;

[0023] According to the use environment, the temperature conditions of the heating device are set for the simulation model as follows: the heating temperature of the external heating module is 80°C, the internal transformer oil target temperature is 5°C, the solution model is selected, and the initialization conditions are set.

[0024] Through modeling and simulation of 220kV transformer, it is found that the control box, connecting pipelines, electric mechanism, ladder and other structures are on both sides of the transformer head and tail. The heatable area at both ends is small, and the heating power required for heating a single group of modules at both ends is large. The heatable area in the middle is relatively concentrated, and the heating power of a single group of modules is small. At the same time, considering the up and down, inside and outside circulation paths of the internal transformer oil, an intelligent temperature control device for transformer insulating oil is comprehensively configured. A good thermodynamic cycle is achieved through different power distributions, so that the temperature of each part can rise evenly to 5°C.

[0025] Furthermore, the method in which the controller controls N flexible heating sheets to turn on or off according to the received insulating oil temperature and the flexible heating sheet temperature is as follows;

[0026] Step 1: The controller determines whether the received insulating oil temperature is lower than a first threshold value, and if so, turns on N flexible heating sheets;

[0027] Step 2: After N flexible heating sheets are turned on, the controller determines whether the received temperature of the flexible heating sheets reaches the second threshold value, and at the same time determines whether the temperature of the insulating oil reaches the first threshold value; if the temperature of the flexible heating sheets reaches the second threshold value and the temperature of the insulating oil reaches the first threshold value, the N flexible heating sheets are turned off and the process proceeds to step 1; if the temperature of the flexible heating sheets does not reach the second threshold value and the temperature of the insulating oil reaches the first threshold value, the N flexible heating sheets are turned off and the process proceeds to step 1; if the temperature of the flexible heating sheets reaches the second threshold value and the temperature of the insulating oil does not reach the first threshold value, the N flexible heating sheets are turned off and the process proceeds to step 3;

[0028] Step 3: After turning off the N flexible heating sheets, if the insulating oil temperature does not reach the first threshold, it is determined whether the heating sheet temperature is lower than the third threshold. If so, the N flexible heating sheets are turned on and the process goes to step 2.

[0029] Specifically, when the intelligent temperature control device for transformer insulating oil heats the insulating oil, the surface temperature range of the heating plate is 70-80°C. When the heating temperature reading reaches 80°C, the heating is suspended. When the temperature reading is lower than 70°C, the heating is started. This cycle continues until the measured oil temperature reaches 5°C above zero, and then the heating is stopped.

[0030] Furthermore, the calculation method of the insulating oil heating power in step 2 is:

[0031] Among them, Q is the heating power of the insulating oil, λ is the thermal conductivity of the insulation material, S is the total heat dissipation area of ​​the transformer, T w To maintain the temperature of the insulating oil, T h is the minimum ambient temperature, δ is the thickness of the transformer insulation layer, T is the heating time, and D is the conversion constant for converting kilocalories into kilowatt-hours, D=860.

[0032] Specifically, taking the Taikai 220kV transformer model SPZ18-220000 / 220 as an example, the design analysis of the commonly used types of oil tank bodies of 220kV transformers is carried out:

[0033]

[0034] λ is the thermal conductivity of the insulation material. The insulation material is EPDM foam rubber, and its thermal conductivity is 0.25W / mk;

[0035] S is the total heat dissipation area of ​​the transformer. The total heat dissipation area of ​​the entire oil tank body is about 41.18m2;

[0036] T w To maintain the temperature of the insulating oil, the oil temperature is maintained at about 5°C;

[0037] T h The lowest ambient temperature is about -40℃.

[0038] δ is the thickness of the transformer insulation layer. The thickness of the insulation layer is 20 mm, which is 0.02 m.

[0039] Engineering safety factor 1.2;

[0040] T is the heating time, designed to be 1h;

[0041] D is the conversion constant for converting kilocalories into kilowatt-hours, D=860.

[0042] The calculated Q is 32.3kW; therefore, according to the calculation, by providing the transformer equipment with 33kW of heating power, the internal transformer oil temperature can be raised to 5°C within 1 hour.

[0043] Furthermore, the calculation method of the number N of flexible heating sheets is:

[0044] Among them, Q is the heating power of the insulating oil, q is the thermal power of a single flexible heating sheet, To round up.

[0045] According to the simulation analysis results, the heatable areas at both ends of the transformer are small, while the heatable area in the middle is more concentrated. According to the thermal power q of a single flexible heating sheet, the number of heating sheets is comprehensively configured so that its total power meets the heating requirements.

[0046] Further, the first threshold is 5°C, the second threshold is 80°C, and the third threshold is 70°C.

[0047] Specifically, the temperature rise of oil-immersed transformers is as follows: 55K when oil is in contact with air, 60K when oil is not in contact with air, and the windings of oil-immersed transformers are all insulated with Class A. According to my country's climate conditions, it is stipulated that +40°C is the maximum temperature of the ambient air, and on this basis, it is stipulated that the temperature of the oil top should not exceed 95°C or 100°C when the transformer is fully loaded. In order to prevent the transformer oil from deteriorating too quickly, the maximum oil temperature is stipulated to be 85°C. This application comprehensively considers the characteristics of the insulating oil, transformer sealing ring and the paint layer on the outer shell of the transformer. In order to ensure the life of the insulating oil and internal components, the temperature resistance of the transformer insulating oil shall not exceed 85°C. Taking into account that the heating of the heating plate causes the local temperature rise of the insulating oil to be faster, and taking into account the thermal efficiency, the temperature range of the flexible heating plate is set to 70-80°C.

[0048] Further, the heat-insulating shell is made of V-0 flame-retardant material. Specifically, the heat-insulating shell can prevent heat loss, improve thermal efficiency, and shorten heating time.

[0049] Furthermore, the flexible heating sheet includes a flexible shell and an electric heating unit, which is wrapped inside the flexible shell and used to increase the temperature after power is supplied; the flexible shell is made of silicone rubber material, and the electric heating unit is a nickel-chromium alloy sheet.

[0050] Specifically, compared with traditional resistance wire heating materials, nickel-chromium alloy sheets have good waterproof properties and excellent flame retardant properties.

[0051] A method for installing an intelligent temperature control device for transformer insulating oil,

[0052] An intelligent temperature control device for transformer insulating oil is fixed between the outer surface of the transformer and the expansion tooling through an expansion tooling, wherein the expansion tooling comprises a fixed plate, an adjusting bolt and a movable plate; one end of the adjusting bolt is fixedly connected to the fixed plate, a bolt hole is arranged on the movable plate, the movable plate is sleeved on the bolt through the bolt hole, and a nut is arranged under the bolt hole of the movable plate; the distance between the fixed plate and the movable plate is adjusted by adjusting the position of the nut so that the fixed plate and the movable plate are respectively closely attached to the top and the bottom of the transformer.

[0053] Specifically, a simplified model is performed on the main part of the transformer. The front and rear sides of the transformer are the transformer radiators. The insulating oil of the transformer is located in the transformer shell. An intelligent temperature control device is arranged on the outside of the transformer. The temperature difference between the upper and lower layers and the inner and outer layers of the insulating oil constitutes a convection circulation of the insulating oil so that the internal low-temperature insulating oil is heated, and the temperature of the insulating oil is made uniform and stable through circulation. The expansion tooling fixes the heating module on the outer surface of the transformer, and the heating module can be further assisted in fixing by fixing methods such as magnetic suction, hooks, stainless steel pull ropes, and folded edge holes to make it close to the surface of the transformer.

[0054] At this time, after completing on-site maintenance and testing operations, the heating device can be disassembled when the surface temperature drops below 30°C, so that the heating device can be reused.

[0055] The installation steps of the expansion tool are as follows: (1) Fix a strong magnet on the intelligent temperature control device, and place the intelligent temperature control device close to the center of the heatable area in the empty space on both sides of the transformer wall. One person presses the intelligent temperature control device to make it adsorbed on the transformer shell, and at the same time, one person uses the expansion tool to fix and install both ends; (2) Align the support panels on both sides of the expansion tool with the outer protruding support structure surface of the transformer oil tank body and the side of the heating plate shell; (3) After aligning the two sides, tighten the nuts on the middle section bolts, lengthen the distance between the two side plates and fix the distance through the combination of bolts and nuts. After fixing one end, fix the other side. After fixing at least two places on one side, no more pressing is required. At this time, one person can complete the remaining installation work; (4) The expansion tool should be fixed to prevent the outer shell of the heating plate from being deformed by excessive extrusion. After fixing the heating plate, fix and connect the platinum resistor and the lead wire to complete the installation.

[0056] The steps for disassembling the expansion tooling are as follows: (1) When the intelligent temperature control device is finished, it can be disassembled when the surface temperature of the flexible heating plate drops below 30°C; after cutting off the power supply of the intelligent temperature control device, first disassemble the expansion tooling at both ends of the intelligent temperature control device, and loosen the nuts in the reverse direction to release the clamping effect of the expansion tooling; (2) After removing most of the expansion tooling on both sides, leave one on each side for the last removal, and two people are required to cooperate to remove the last two expansion toolings; after the intelligent temperature control device and the expansion tooling are recycled separately, they can be reused later.

[0057] To sum up, the intelligent temperature control device of the present application is easy to transport, install, and adjust, and is simple and quick to operate. It can be recycled, the heating power refers to simulation analysis and theoretical calculation, the heating plate is arranged reasonably and appropriately, and the specifications of the intelligent temperature control device can be tailored to transformers of different specifications, and customized production can be carried out according to actual conditions to meet the use requirements.

Claims

1. An intelligent temperature control device for transformer insulating oil, characterized in that: include: A thermal insulation housing and a first temperature sensor; A controller, a second temperature sensor and N flexible heating plates are arranged in the thermal insulation shell. A plug-in interface is arranged on the side of each flexible heating plate, and every two adjacent heating plates are connected through the plug-in interface; the flexible heating plate is used to increase the temperature after power is turned on; the first temperature sensor is used to obtain the insulating oil temperature and send the insulating oil temperature to the controller; the second temperature sensor is used to obtain the flexible heating plate temperature and send the flexible heating plate temperature to the controller, and the controller is used to control the N flexible heating plates to be turned on or off according to the received insulating oil temperature and the flexible heating plate temperature.

2. The intelligent temperature control device for transformer insulating oil according to claim 1, characterized in that: The method for the controller to control N flexible heating sheets to turn on or off according to the received insulating oil temperature and the flexible heating sheet temperature is as follows; Step 1: The controller determines whether the received insulating oil temperature is lower than a first threshold value, and if so, turns on N flexible heating sheets; Step 2: After N flexible heating sheets are turned on, the controller determines whether the received temperature of the flexible heating sheets reaches the second threshold value, and at the same time determines whether the temperature of the insulating oil reaches the first threshold value; if the temperature of the flexible heating sheets reaches the second threshold value and the temperature of the insulating oil reaches the first threshold value, the N flexible heating sheets are turned off and the process proceeds to step 1; if the temperature of the flexible heating sheets does not reach the second threshold value and the temperature of the insulating oil reaches the first threshold value, the N flexible heating sheets are turned off and the process proceeds to step 1; if the temperature of the flexible heating sheets reaches the second threshold value and the temperature of the insulating oil does not reach the first threshold value, the N flexible heating sheets are turned off and the process proceeds to step 3; Step 3: After turning off the N flexible heating sheets, if the insulating oil temperature does not reach the first threshold, it is determined whether the heating sheet temperature is lower than the third threshold. If so, the N flexible heating sheets are turned on and the process goes to step 2.

3. The intelligent temperature control device for transformer insulating oil according to claim 1, characterized in that: The flexible heating sheet comprises a flexible shell and an electric heating unit, wherein the electric heating unit is wrapped inside the flexible shell and is used for increasing the temperature after being energized.

4. The intelligent temperature control device for transformer insulating oil according to claim 1, characterized in that: The calculation method of the number of flexible heating sheets N is: Among them, Q is the heating power of the insulating oil, q is the thermal power of a single flexible heating sheet, To round up.

5. The intelligent temperature control device for transformer insulating oil according to claim 4, characterized in that: The calculation method of the insulating oil heating power in step 2 is: Among them, Q is the heating power of the insulating oil, λ is the thermal conductivity of the insulation material, S is the total heat dissipation area of ​​the transformer, T w To maintain the temperature of the insulating oil, T h is the minimum ambient temperature, δ is the thickness of the transformer insulation layer, T is the heating time, and D is the conversion constant for converting kilocalories into kilowatt-hours, D=860.

6. The intelligent temperature control device for transformer insulating oil according to claim 2, characterized in that: The first threshold is 5°C, the second threshold is 80°C, and the third threshold is 70°C.

7. The intelligent temperature control device for transformer insulating oil according to claim 1, characterized in that: The thermal insulation shell is made of V-0 grade flame retardant material.

8. The intelligent temperature control device for transformer insulating oil according to claim 3, characterized in that: The flexible shell is made of silicone rubber material, and the energized heating unit is a nickel-chromium alloy sheet.

9. A method for installing an intelligent temperature control device for transformer insulating oil, characterized in that: An intelligent temperature control device for transformer insulating oil is fixed between the outer surface of the transformer and the expansion tooling through an expansion tooling, wherein the expansion tooling comprises a fixed plate, an adjusting bolt and a movable plate; one end of the adjusting bolt is fixedly connected to the fixed plate, a bolt hole is arranged on the movable plate, the movable plate is sleeved on the bolt through the bolt hole, and a nut is arranged under the bolt hole of the movable plate; the distance between the fixed plate and the movable plate is adjusted by adjusting the position of the nut so that the fixed plate and the movable plate are respectively closely attached to the top and the bottom of the transformer.

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