Transformer winding temperature measurement calibrator

Abstract

The invention discloses a transformer winding temperature measurement calibrator, and relates to the technical field of transformer winding temperature measurement. The system comprises a constant temperature system and a thermal simulation correction system, and the constant temperature system is in signal connection with the thermal simulation correction system. The constant temperature system comprises a heating unit and a refrigerating unit; according to the invention, the heating unit composed of the electric heater, the temperature controller, the heat exchanger and the electric controller and the refrigeration unit composed of the compression refrigeration system and the refrigerant circulation refrigeration system are arranged, the heating unit accurately controls the heating temperature of the thermostatic bath, and meanwhile, the refrigerant circulation refrigeration system controls the flow of cooling water entering the thermostatic bath; the purposes of accelerating cooling and controlling the temperature rise rate are achieved, so that the current flowing through the heating element is adjusted through the current matcher in the process of measuring the temperature rise of the transformer winding during the temperature rise test of the transformer, and the value of the transformer winding thermometer can reflect the temperature of the transformer winding more accurately.

Description

Technical Field

[0001] The invention relates to the technical field of transformer winding temperature measurement, in particular to a transformer winding temperature measurement and calibration instrument. Background Art

[0002] Transformer winding refers to the circuit part of the transformer, which is wound by copper or aluminum wire with high conductivity. It is used in power systems. The winding should have sufficient insulation strength, mechanical strength and heat resistance.

[0003] The transformer winding temperature is mostly measured using a transformer winding thermometer, which is designed for oil-immersed power transformers and mostly uses the "thermal simulation" method to indirectly measure the transformer winding temperature;

[0004] However, the existing technology still has some defects when calibrating transformer winding thermometers:

[0005] 1. At present, the existing technology mostly uses a constant temperature bath, that is, a constant temperature oil bath, to calibrate the transformer winding thermometer. The constant temperature oil bath has a relatively single temperature control method in the process of controlling temperature rise and temperature drop, which leads to a low rate and efficiency of temperature rise and temperature drop. In addition, it is inconvenient to accurately reflect the temperature of the transformer winding during the transformer temperature rise test;

[0006] 2. At the same time, when the existing technology calibrates the transformer winding thermometer, the measuring element used to measure the transformer winding thermometer is mostly inconvenient to accurately calibrate the thermal simulation additional temperature rise indication error and thermal simulation time constant of the transformer winding thermometer, resulting in low accuracy of the transformer winding thermometer calibration;

[0007] In view of the above problems, the inventor proposes a transformer winding temperature measuring and calibrating instrument to solve the above problems. Summary of the invention

[0008] In order to solve the above-mentioned problem, the purpose of the present invention is to provide a transformer winding temperature measuring and calibrating instrument.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions: a transformer winding temperature measuring and calibrating instrument, the temperature measuring and calibrating instrument comprises a constant temperature system and a thermal simulation correction system, the constant temperature system and the thermal simulation correction system are connected by signals;

[0010] The constant temperature system includes a heating unit and a refrigeration unit;

[0011] The thermal simulation correction system includes a measuring unit, a data processing unit, an alarm unit and a management unit;

[0012] The refrigeration unit includes a compression refrigeration system and a refrigerant circulation refrigeration system.

[0013] Preferably, the terminal device of the constant temperature system includes a constant temperature bath, and the terminal device of the heating unit includes an electric heater, a temperature controller, a heat exchanger and an electrical controller.

[0014] Preferably, the terminal equipment of the compression refrigeration system includes a compressor, a condenser, an expansion valve and an evaporator.

[0015] Preferably, the terminal equipment of the refrigerant circulation refrigeration system includes a compressor, a condenser, a liquid receiver, a drying filter, a thermal expansion valve and an evaporator.

[0016] Preferably, the terminal equipment of the measuring unit comprises a constant current source, an AC ammeter A1, an AC ammeter A2 and a DC ammeter A3, and the constant current source, the AC ammeter A1, the AC ammeter A2 and the DC ammeter A3 are connected via wires.

[0017] Preferably, the data processing unit is used to record and store measurement data, the alarm unit is used to alarm the winding temperature, and the management unit is used to switch the temperature unit and display the battery status.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. In the present invention, the heating unit is composed of an electric heater, a temperature controller, a heat exchanger and an electrical controller, and the refrigeration unit is composed of a compression refrigeration system and a refrigerant circulation refrigeration system. The heating unit accurately controls the temperature rise of the thermostatic bath. At the same time, the refrigerant circulation refrigeration system controls the cooling water flow entering the thermostatic bath, so as to achieve the purpose of accelerating the temperature drop and controlling the temperature rise rate. Therefore, when the transformer is subjected to a temperature rise test, the current flowing through the heating element is adjusted through the current matcher during the process of measuring the temperature rise of the transformer winding, so that the value of the transformer winding thermometer can more accurately reflect the temperature of the transformer winding;

[0020] 2. In the present invention, the actual current value output by the AC constant current source and the current corresponding to the additional temperature rise of the transformer winding are measured respectively through a measuring unit composed of a constant current source, an AC ammeter A1, an AC ammeter A2 and a DC ammeter A3, so that the indication error of the additional temperature rise of the transformer winding thermometer and the thermal simulation time constant can be accurately calibrated, and the function of factory calibration of the current corresponding to the additional temperature rise of the transformer winding of the transformer winding thermometer is achieved. At the same time, the constant current source can output a stable AC current, so as to accurately and quickly detect the temperature of the transformer winding, and improve the accuracy of the transformer winding thermometer calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The present invention is a schematic diagram of the composition of a transformer winding temperature measuring and calibrating instrument.

[0023] Figure 2 It is a schematic diagram of the composition of the constant temperature system of the present invention.

[0024] Figure 3 It is a schematic diagram of the composition of the measuring unit of the present invention.

[0025] Figure 4 This is a circuit diagram of a constant current source of a measuring unit of the present invention.

[0026] Figure 5 The figure is a schematic diagram of the verification principle of an embodiment of the present invention.

[0027] In the figure: 100, constant temperature system; 200, thermal simulation correction system; 300, measurement unit; 400, data processing unit; 500, alarm unit; 600, management unit; 110, heating unit; 120, refrigeration unit; 1210, compression refrigeration system; 1220, refrigerant circulation refrigeration system. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example: Figure 1-5 As shown, the present invention provides a transformer winding temperature measuring and calibrating instrument, the temperature measuring and calibrating instrument comprises a constant temperature system 100 and a thermal simulation correction system 200, the constant temperature system 100 and the thermal simulation correction system 200 are signal connected;

[0030] The constant temperature system 100 includes a heating unit 110 and a refrigeration unit 120;

[0031] The thermal simulation calibration system 200 includes a measurement unit 300, a data processing unit 400, an alarm unit 500 and a management unit 600;

[0032] The refrigeration unit 120 includes a compression refrigeration system 1210 and a refrigerant circulation refrigeration system 1220 .

[0033] The terminal equipment of the constant temperature system 100 includes a constant temperature tank, and the terminal equipment of the heating unit 110 includes an electric heater, a temperature controller, a heat exchanger and an electrical controller.

[0034] The terminal equipment of the compression refrigeration system 1210 includes a compressor, a condenser, an expansion valve and an evaporator.

[0035] The terminal equipment of the refrigerant circulation refrigeration system 1220 includes a compressor, a condenser, a liquid receiver, a drying filter, a thermal expansion valve and an evaporator.

[0036] The terminal equipment of the measuring unit 300 includes a constant current source, an AC ammeter A1, an AC ammeter A2 and a DC ammeter A3, and the constant current source, the AC ammeter A1, the AC ammeter A2 and the DC ammeter A3 are connected by wires.

[0037] The data processing unit 400 is used to record and store the measurement data for subsequent analysis and comparison, and to track the changing trend of the transformer winding temperature so as to detect abnormalities in a timely manner. The alarm unit 500 is used for winding temperature alarms, and the management unit 600 is used for temperature unit switching and battery status display, thereby improving the practicality and convenience of the terminal device.

[0038] When the transformer winding temperature is measured by the transformer winding thermometer, the transformer winding temperature is the angular displacement of the elastic bellows in the instrument caused by the transformer top oil temperature, superimposed on the angular displacement of the heating element in the instrument, thereby indicating the transformer winding temperature. The heating element compensates for different copper-oil temperature differences through changes in the matching device and the load conditions on the secondary side of the transformer CT.

[0039] The transformer winding thermometer is based on an oil temperature meter, equipped with a current matcher and an electric heating element. The current proportional to the load is taken out by the transformer current transformer, adjusted by the current matcher, and then the electric heating element embedded in the elastic element generates heat, which increases the displacement of the elastic element. Therefore, after the transformer is loaded, the displacement of the elastic element is determined by the top oil temperature of the transformer and the load current of the transformer. The temperature indicated by the transformer winding thermometer is the sum of the top oil temperature of the transformer and the temperature rise of the coil to the oil, reflecting the average temperature of the hottest part of the transformer winding under test;

[0040] The current matcher is a current conversion device. Its function is to provide working current for the transformer winding thermometer. The current output from the current transformer of the transformer is converted by the current matcher, and then an adjustable current is provided to the electric heating element inside the transformer winding thermometer, so as to simulate the temperature of the hottest part of the transformer winding.

[0041] The winding thermometer adopts the principle of thermal simulation technology. It uses the method of superimposing the transformer top oil temperature on the transformer winding temperature difference to indirectly measure the transformer winding temperature. The additional temperature rise reported by the electric heating element is superimposed on the transformer top oil temperature measured by the pressure thermometer principle through the corresponding material structure in the winding thermometer. The transformer winding thermometer is composed of a temperature package, a measuring bellows, a capillary, an elastic element, a current matcher and an electric heating element. The temperature package, the measuring bellows and the capillary connecting the two constitute the measuring part reflecting the transformer top oil temperature. The current matcher and the electric heating element constitute the thermal simulation part reflecting the change of the winding load current. It can convert the indicated temperature into a standard (4-20) mA remote transmission signal. The temperature package in the measurement system is filled with a working medium whose volume changes with temperature. The change of the transformer top oil temperature causes the displacement of the measuring bellows to change. In the winding thermometer, the current Ip, which is proportional to the load, is obtained by the current transformer. After being converted into thermal current Is by the current matcher, it generates additional displacement through the electric heating element. The displacement of the bellows is driven by the instrument pointer mechanism after mechanical amplification, so that the temperature measuring device indirectly measures and indicates the temperature of the transformer winding.

[0042] The working current of the transformer winding thermometer is different because the CT rated output current of each oil-immersed transformer may be different, and the temperature difference between the coil and the oil may also be different. Different temperature difference values ​​require different working currents ls for simulation. Before the AC converter leaves the factory, the AC converter working current ls is set at 1.0A based on the CT rated output current of 5A and the average temperature rise of the winding to the oil temperature △T=20K. If the user's use occasion does not meet the above parameters, the working current should be set before use;

[0043] The core content of the transformer winding thermometer calibration is the temperature rise test. When the transformer is subjected to the temperature rise test, the temperature rise of the transformer winding is measured, and the current flowing through the heating element is adjusted through the current matcher, so that the value of the thermometer can more accurately reflect the temperature of the transformer winding.

[0044] The temperature in the constant temperature system 100 (constant temperature bath) shall not deviate from the measuring point by ±0.5°C when the temperature in the constant temperature bath reaches the set temperature. The temperature package of the temperature controller to be measured and the standard thermometer are inserted into the constant temperature bath. After the indication is stable for a period of time, the indication of the controlled temperature controller, the remote signal and the standard thermometer are read at the same time. The indication error of the temperature controller to be measured is as follows:

[0045] T W =T S -(T B +TX )

[0046] The indication error of the remote signal device of the measured temperature controller is calculated as follows:

[0047] T Y =T S -(T B +T X )

[0048] The indication deviation between the measured temperature controller and the remote signal device is as follows:

[0049] ∨T=|T W -T Y |

[0050] Adjust the power frequency current generator to simulate the effect of transformer temperature rise on temperature. The current flowing through the heating element is adjusted through the current matcher to keep the heating current constant. After stabilization, read the indications of the thermostat, remote signal, constant temperature bath temperature, etc., and calculate the verification result according to the corresponding national standard formula (reference Figure 5 , verification principle diagram);

[0051] In the process of controlling the constant temperature system 100, electric heating is performed by the heating unit 110 composed of an electric heater, a temperature controller, a heat exchanger and an electrical controller to accurately control the temperature rise of the constant temperature bath. In the cooling process, when the bath liquid temperature of the constant temperature bath is lower than 45°C, two refrigeration methods can be used to cool the bath liquid at the same time, namely, the compression refrigeration system 1210 and the refrigerant circulation refrigeration system 1220, so as to improve the cooling rate and efficiency. When the bath liquid temperature of the constant temperature bath is higher than 45°C, the compression refrigeration system 1210 is automatically shut down for the purpose of protecting the compressor, and only the refrigerant circulation refrigeration system 1220 is used to achieve the purpose of cooling the bath liquid.

[0052] A refrigerant circulation refrigeration system 1220 composed of a compressor, a condenser, a liquid storage tank, a drying filter, a thermal expansion valve and an evaporator, wherein the compressor, the condenser, the liquid storage tank, the drying filter, the thermal expansion valve and the evaporator are connected by a pipeline, and a refrigerant return valve, a refrigerant cooling valve and a rotor flow meter are installed on the pipeline, and the temperature of the cooling water to be produced can be set. When the cooling water reaches a preset temperature, an external circulating water pump controls the cooling water to enter the refrigerant circulation refrigeration system 1220 through the pipeline, and at the same time, the cooling water flow entering the constant temperature tank can be controlled, thereby achieving the purpose of accelerating the cooling and controlling the temperature rise rate;

[0053] For the control of cooling rate, the constant temperature bath is cooled by compressor when the temperature is below 45℃, and the cooling water circulation with a small flow rate (0-100mL / min) above 45℃ can meet the requirements. For the control of heating rate, different temperature control modes are used for segmented adjustment. According to the different temperatures, the rotor flowmeter is continuously adjusted to change the flow rate of cooling water flowing through the constant temperature bath during the refrigerant circulation, so as to achieve the purpose of controlling the heating rate. Through segmented adjustment, the constant temperature heating rate can be controlled at ≤1.0℃ / min;

[0054] The measuring unit 300 is composed of a constant current source, an AC ammeter A1, an AC ammeter A2 and a DC ammeter A3, wherein the AC ammeter A1 adopts a 0.2-level AC ammeter of (0-5)A, the AC ammeter A2 adopts a 0.5-level AC ammeter of (0-2)A, and the DC ammeter A3 adopts a DC ammeter of (0-30)mA. The AC ammeter A1 is used to measure the actual current value output by the AC constant current source, and the AC ammeter A2 is used to measure the current corresponding to the additional temperature rise of the transformer winding, so as to accurately calibrate the indication error and thermal simulation time constant of the additional temperature rise of the transformer winding thermometer, so as to achieve the function of factory calibration of the current corresponding to the additional temperature rise of the transformer winding of the transformer winding thermometer. At the same time, the constant current source can output a stable AC current, so as to accurately and quickly detect the temperature of the transformer winding.

[0055] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A transformer winding temperature measuring and calibration instrument, characterized in that: The temperature measuring and calibrating instrument comprises a constant temperature system (100) and a thermal simulation correction system (200), wherein the constant temperature system (100) and the thermal simulation correction system (200) are signal-connected; The constant temperature system (100) comprises a heating unit (110) and a refrigeration unit (120); The thermal simulation correction system (200) comprises a measuring unit (300), a data processing unit (400), an alarm unit (500) and a management unit (600); The refrigeration unit (120) includes a compression refrigeration system (1210) and a refrigerant circulation refrigeration system (1220).

2. A transformer winding temperature measuring and calibrating instrument as claimed in claim 1, characterized in that: The terminal equipment of the constant temperature system (100) includes a constant temperature tank, and the terminal equipment of the heating unit (110) includes an electric heater, a temperature controller, a heat exchanger and an electrical controller.

3. A transformer winding temperature measuring and calibrating instrument as claimed in claim 1, characterized in that: The terminal equipment of the compression refrigeration system (1210) includes a compressor, a condenser, an expansion valve and an evaporator.

4. A transformer winding temperature measuring and calibrating instrument as claimed in claim 1, characterized in that: The terminal equipment of the refrigerant circulation refrigeration system (1220) includes a compressor, a condenser, a liquid storage tank, a drying filter, a thermal expansion valve and an evaporator.

5. A transformer winding temperature measuring and calibrating instrument as claimed in claim 1, characterized in that: The terminal equipment of the measuring unit (300) comprises a constant current source, an AC ammeter A1, an AC ammeter A2 and a DC ammeter A3, and the constant current source, the AC ammeter A1, the AC ammeter A2 and the DC ammeter A3 are connected via wires.

6. A transformer winding temperature measuring and calibrating instrument as claimed in claim 1, characterized in that: The data processing unit (400) is used to record and store measurement data, the alarm unit (500) is used to alarm the winding temperature, and the management unit (600) is used to switch the temperature unit and display the battery status.

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