DE102022124183A1 - Oil transformer with an oil expansion tank - Google Patents

Abstract

There will be an oil transformer comprising a transformer tank, an oil conservator, a flow channel connecting the transformer tank with a first opening in the oil conservator, a cell for receiving oil, means for conveying oil from the oil conservator into the cell, an antenna for acting on the Oil in the cell with a measurement signal and a sensor electrically connected to the antenna for measuring an oil quality of the oil transformer are described.

Description

TECHNICAL FIELD

The present disclosure relates to an oil transformer having an oil conservator and a technique for measuring the oil quality of an oil transformer including an oil conservator.

BACKGROUND

Electric oil transformers are power transformers that are mostly used in power distribution networks. Such oil transformers are, for example, from the DE202008017356U1 known. Oil transformers include an oil-filled transformer tank in which the transformer core with primary and secondary windings is arranged. For insulation, the primary and secondary windings can be wrapped with cellulose paper. The oil serves as an electrical insulation medium and as a cooling medium to dissipate heat loss generated during transformer operation. Depending on the operating oil temperature, the oil increases and decreases in volume. This is also referred to as the oil transformer “breathing”.

Oil transformers usually include an oil expansion vessel arranged above the transformer tank and connected to the transformer tank via a flow channel. With the help of the oil expansion vessel, changes in the volume of the oil can be compensated for. The oil expansion vessel is used to hold a volume of oil that arises due to the thermal expansion of the oil during temperature fluctuations in the transformer due to changes in load or changes in ambient temperature. A compressible membrane filled with air can be arranged inside the oil expansion vessel. Depending on the expansion state of the oil in the transformer, the membrane is compressed, with the interior of the transformer tank, the oil expansion vessel and the flow channel forming a closed system. A magnetic oil level indicator (MOG) can be used to monitor the oil level in the oil conservator.

As the oil transformer ages, the oil becomes contaminated by moisture and fiber materials in the insulating material of the windings. In addition, dissolved gases resulting from chemical reactions in the oil can contaminate the oil. To ensure safe operation and avoid operational interruptions or power outages, the oil must be checked at regular intervals and replaced if necessary.

Oil monitoring is typically done in one of the following ways: An oil sample is manually removed from the transformer and sent to a laboratory for analysis. Tests of the insulation resistance and the dielectric breakdown voltage of the oil are then carried out in the laboratory. Furan analysis can also be carried out in the laboratory. Alternatively, it is known to analyze the oil at regular intervals in a measuring device. Gas chromatography can be carried out, but has the disadvantage that it is time-consuming and costly and must be carried out by a specialist. Furthermore, photoacoustic spectroscopy can be carried out.

Known techniques for monitoring the oil in an oil transformer also have the following disadvantages: some techniques cannot be retrofitted and require a relatively high level of personnel to install and configure the measuring devices. It is often necessary that the transformer is not operated during the installation of the measuring devices and must be switched off. Furthermore, known measurement techniques can be influenced by electromagnetic pulses. Measuring sensors that are attached directly to the surface of the main tank of the transformer can be influenced by partial discharges. Such partial discharges can generate electromagnetic pulses in the ultra-high frequency range (300 MHz to 3 GHz), which can lead to measurement errors or measurement inaccuracies in the measuring devices. The ambient and/or surface temperature of the transformer can also cause problems. Electronic measuring devices, for example operated near the leg and yoke area of the transformer, are exposed to high temperatures (oil temperature rise due to high voltage loads). The increased temperature can cause the measuring devices to no longer function properly, which can lead to measurement errors or measurement inaccuracies or even measuring device failures. Measuring devices that collect oil samples from an outlet valve at the bottom of the oil transformer main tank may also be mixed with contaminated particles. Fibers and moisture from the insulating materials can combine with the oil and cause residue to settle at the bottom of the transformer. Oil samples collected in this area are often contaminated by residues, which can lead to inaccurate analysis of oil quality.

SHORT ABSTRACT

The present disclosure is based on the object of providing an oil transformer with an oil expansion vessel which makes it possible to determine the oil quality of the oil transformer in a simple and reliable manner.

To solve this problem, an oil transformer comprising a transformer tank, an oil conservator, a flow channel connecting the transformer tank with a first opening in the oil conservator, a cell for receiving oil, means for conveying oil from the oil conservator into the cell, an antenna for applying a measurement signal to the oil in the cell and a sensor electrically connected to the antenna for measuring an oil quality of the oil transformer.

The oil transformer can be any type of oil transformer that has an oil expansion vessel to compensate for changes in the volume of the transformer oil. The shape of the oil expansion tank is not limited to a specific shape. The oil expansion vessel can be designed, for example, as a cylinder, cuboid, cube or prism. The oil expansion vessel can be an expansion radiator, an expansion vessel with a nitrogen cushion or with a rubber bag or rubber membrane. In particular, there can be a compressible membrane in the oil expansion vessel, which is compressed or decompressed depending on the oil level in the oil expansion vessel. The transformer with core and coils is in an oil bath in the transformer tank. When connecting the transformer tank to the first opening in the oil expansion vessel through the flow channel, a Buchholz protection relay can be provided in the flow channel. Further components, such as various cavities, can be provided in the flow channel. The transformer tank, the flow channel and/or the oil expansion vessel can be steel structures.

Depending on the shape of the oil expansion vessel, the antenna is arranged at corresponding positions outside the oil expansion vessel on the oil expansion vessel, or on or in a second opening of the oil expansion vessel. The second opening can be a valve opening with a gas release valve (pressure relief valve) arranged therein. The second opening can be arranged at an upper end of the oil expansion vessel or laterally on the oil expansion vessel.

The antenna is electrically connected to the sensor. In order to avoid measurement inaccuracies, the antenna can be arranged or attached directly to the oil expansion vessel. The sensor can be arranged at a distance from the oil expansion vessel, for example > 1m away. The antenna and the sensor can be connected to each other via cable or via radio interfaces (e.g. via Wi-Fi or Bluetooth). The antenna can be a transmitting antenna and a receiving antenna, an integrated transmitting and receiving antenna, or two integrated transmitting and receiving antennas. In particular, the antenna(s) can be designed as Vivaldi antennas. Vivaldi antennas can be used advantageously due to their wide bandwidth, low cross polarization and constant group delay. The antenna(s) may also be designed as ultra-wideband (UWB) antenna(s), spiral antennas or other types of antennas. The antenna and the sensor can also be designed as a unit or a module, for example in a housing. The sensor can further include a communication interface for communicating with a cloud computer.

To attach the antenna, the cells and the means for conveying oil from the oil expansion vessel into the cell, a fastening device can be provided, which allows for a detachable attachment of the antenna, the cells and the means for conveying oil from the oil expansion vessel into the cell . in the oil expansion vessel. Other forms of fastening, such as screws or magnetic fastening, are also conceivable.

The sensor can, for example, comprise a baseband transmitter, a baseband receiver and a digital backend, with the help of the signals generated by the baseband transmitter and the signals received by the baseband receiver to determine the oil quality in the oil expansion vessel or the oil transformer can. Oil quality can be quality characteristics defined in the IEC 60422 standard. In particular, the sensor is set up to use the received measurement signals to obtain information regarding the color, water content and/or acid content of the oil, based on which a statement can be made about the quality of the oil in the oil transformer. For example, the signals are used to determine the refractive index and/or the loss factor of the oil. The sensor can be a non-contact near-field sensor for dielectric spectroscopy. The sensor may also be configured to perform broadband dielectric spectroscopy (BDS). Is the sensor For example, designed for ultra-wideband impedance spectroscopy, the oil can be subjected to a pulsed alternating current signal. Furthermore, a combined frequency domain/time domain technique can be used to characterize the oil. In order to improve the detection accuracy, a baseband signal can be generated by the sensor, which is generated by a combination of several up-converted Gaussian signals. Further components, such as amplifiers, oscilloscopes and a communication interface, can be provided in the sensor. The sensor can also be set up to measure temperature, vibration and/or gas development of the oil.

The sensor can in particular be set up to generate signals, in particular electromagnetic signals, with a frequency of 1 Hz to 3000 GHz and to send them to the antenna, which sends the signals into the oil. Signals with a frequency of 1 Hz to 3000 GHz are then received by the sensor via the antenna. The antenna can be designed as a unit with a transmitting and receiving antenna, so that signals sent into the oil are reflected and received again by the antenna. In particular, it can be a transceiver antenna. The signals can in particular be pulsed signals in the picosecond range. The advantages of the interactions of electromagnetic waves with frequencies from 1 Hz to 3000 GHz are that they generally do not pose any health risks to people and still provide good measurement results.

Even better measurement results can be achieved if the sensor is set up to generate, send and receive signals with a frequency of 3.1 GHz to 10.6 GHz. In particular, the sensor can be set up to be operated in the ultra-wideband (UWB) range.

The cell can be a membrane, for example a rubber membrane, which is designed to absorb oil from the oil expansion vessel. In particular, the oil can flow through the cell, for example pumped from the oil expansion vessel into the cell and analyzed there. Furthermore, the oil can be fed back into the oil expansion vessel after flowing through the cell and being analyzed. Accordingly, the cell can have one or two hose connections.

The cell can be arranged within the oil expansion vessel above a maximum oil level of the oil expansion vessel. This can ensure that the cell does not come into contact with the oil in the oil conservator. The oil quality of the oil in the oil expansion vessel can therefore be determined with minimal oil contact in the oil expansion vessel. The oil contact in the oil expansion vessel can only take place through the means for conveying oil from the oil expansion vessel into the cell. The oil transformer can further comprise an oil level measuring device for measuring the oil level of the oil expansion vessel. In particular, the maximum oil level of the oil expansion vessel can be determined with the oil level measuring device.

Alternatively, the cell can be arranged outside the oil expansion vessel at a second opening of the oil expansion vessel. This allows for easy installation and uninstallation of the cell. The second opening can be arranged at an upper end of the oil expansion vessel. For example, the second opening is arranged at a highest point of the oil expansion vessel. In this case, the antenna receives reflected signals from the signals emitted into the oil. This can prevent the measurement from being distorted by deposits in the oil at the bottom of the oil expansion vessel. Furthermore, the second opening can comprise a valve. In this embodiment, the antenna and the sensor can be designed as a portable measuring system, which enables simple and non-contact measurement of the oil quality without major installation effort. The portable measuring system can further include the means for conveying oil from the oil expansion vessel into the cell. The system consisting of antenna, sensor and means for transporting oil from the oil expansion tank into the cell is designed as a measuring system with minimal or reduced oil contact.

The antenna can be arranged on the cell. For example, the antenna is glued to an outside of the cell. This allows measurement signals to be applied to the oil in the cell without contact. The antenna can also be arranged in the cell, which means that even more precise measurement results can be obtained. The antenna can, for example, have a meander shape. The antenna can thus be designed as a combined transmitting and receiving antenna, in particular as a transceiver antenna.

For reliable transmission and reception of the signals, the oil transformer may further include an ultra-wideband baseband transmitter, an ultra-wideband baseband receiver and a digital backend. The digital backend may include a processor that executes instructions from a computer program.

Furthermore, the oil transformer can include a computing device connected to the sensor, the computing device being set up to process and visualize the measured values measured by the sensor. For example, a measured frequency spectrum can be displayed. The computing device can be, for example, a laptop or tablet computer. The computing device can be set up to calculate values relating to color, water content and/or acidity of the oil based on the measured values measured by the sensor. For example, a fast Fourier transform can be applied to the measurement data. Furthermore, the measurement data can be extracted and visualized in a computing platform of the computing device, such as MATLAB. The computing device can also be implemented as a cloud computer,

The oil transformer may further include a temperature, gas and/or vibration sensor. The temperature, gas and/or vibration sensor can be arranged on or in the oil expansion vessel. In particular, the sensor can be set up to detect abnormalities in the gas generated by the oil transformer. The sensor may also include additional sensor and electronic components that monitor regular operation and condition of the oil transformer.

The means for conveying oil from the oil conservator into the cell may include a hose disposed at least partially within the oil conservator and/or a pipe having a first end extending into the oil in the oil conservator and a second end connected to the cell and a pump for pumping the oil from the oil conservator into the cell. The pump is preferably arranged outside the oil expansion vessel. With this embodiment, an oil quality determination can be realized with minimal oil contact. If the oil is pumped through the cell, another hose and/or another pipe is also provided, which pumps the oil back into the oil expansion vessel and/or a collecting vessel.

The aspects and variants described above can be combined without this being explicitly described. Each of the described design variants can therefore be seen as optional to each design variant or combinations thereof. The present disclosure is therefore not limited to the individual embodiments and variants in the order described or to a specific combination of the aspects and embodiment variants.

BRIEF DESCRIPTION OF THE DRAWINGS

• 1 zeigt eine schematische Darstellung eines Ausführungsbeispiels eines Öltransformators mit einem Ölausdehnungsgefäß; und
• 2 zeigt eine schematische Darstellung eines Ausführungsbeispiels eines Ölausdehnungsgefäßes mit einer Antenneneinheit, einem Sensor und einer Recheneinheit; und

Further advantages, details and features of the oil transformers described here result from the following description of exemplary embodiments and the figures.

• 1 shows a schematic representation of an exemplary embodiment of an oil transformer with an oil expansion vessel; and
• 2 shows a schematic representation of an exemplary embodiment of an oil expansion vessel with an antenna unit, a sensor and a computing unit; and

DETAILED DESCRIPTION

The 1 shows a schematic representation of an exemplary embodiment of an oil transformer with an oil expansion vessel. The oil transformer includes a transformer tank 10 and an oil conservator 20. A flow channel 30 connects the transformer tank 10 to a first opening 22 in the oil conservator 20. The first opening 22 is arranged at a lower end of the oil conservator 20. The transformer tank 10 includes a corresponding opening. In the transformer tank 10, the transformer 15 is mounted on standing blocks 60 in an oil bath 40. The oil expansion vessel 20 is in the 1 shown as an example above the transformer tank 10 in a cylindrical shape. Other shapes (e.g. cuboid, cube or prism) and arrangements (at the same height as the transformer tank 10, further above, etc.) of the oil expansion vessel 20 are conceivable.

There is oil 40 in the flow channel 30 and the housing 26 of the oil expansion vessel 20. As described above, the oil expansion vessel 20 serves to hold oil due to thermal expansion of the oil during temperature fluctuations in the transformer 15, caused by load changes or changes in the ambient temperature. As indicated by the surface 42 of the oil in the oil expansion vessel 20, the oil level in the oil expansion vessel 20 changes accordingly. The oil in the oil expansion vessel 20 compresses a membrane 28 depending on the oil level in the oil expansion vessel 20, which again when the oil level 42 falls is decompressed. At an upper end of the oil expansion vessel 20, a pressure relief valve 50 for releasing excess gas is provided in a second opening 24. Furthermore, the oil transformer includes an oil level measuring device 25 for measuring the oil level 42 in the oil expansion vessel 20. For the sake of clarity, further components of the oil transformer, such as the trans Former core, the coils and a Buchholz protection relay, in the schematic representation of the 1 Not shown. As an alternative to the embodiment of the oil expansion vessel 20 with the membrane 28, an oil expansion vessel of the Atmoseal type or another type can also be provided.

The 2 shows a schematic representation of an exemplary embodiment of an oil expansion vessel. The oil expansion vessel 20 is the one in the 1 shown oil expansion vessel 20, with the same reference numbers 1 and 2 affect the same elements.

The ones in the 2 Arrangement shown comprises a cell 55 for receiving oil 40 from the oil expansion vessel 20, means 57, 58 for conveying oil 40 from the oil expansion vessel 20 into the cell 55, an antenna 85 for applying a measurement signal to the oil 40 in the cell 55, a sensor 70 electrically connected to the antenna 85 for measuring an oil quality of the oil transformer and a computing device 90.

The means 57, 58 for conveying oil 40 from the oil expansion vessel 20 into the cell 55 comprise a hose 57 arranged at least partially in the oil expansion vessel 20 with a first end which extends into the oil 40 in the oil expansion vessel 20 and a second end, which is connected to the cell 55, and a pump 58 for pumping the oil 40 from the oil conservator 20 into the cell 55. The hose 57 extends through the opening 24, with the cell 55 being arranged outside the oil conservator 20 at the opening 24 .

In the 2 a minimum oil level 42 is shown in the oil expansion vessel 20, the hose 57 being designed such that the first end of the hose 57 always reaches below the minimum oil level 42.

The pump 58 pumps oil 40 from the oil expansion vessel 20 into the cell 55. It is also conceivable that the pump 58 pumps the oil 40 through the cell 55, i.e. the oil 40 is returned to the oil expansion vessel 20. The pump 58 is designed as an electric pump and is electrically connected to the antenna 85. The pump 58 is located near the antenna 85.

According to an alternative embodiment (not shown), the cell 55 is arranged in the oil expansion vessel 20, in particular above a maximum oil level of the oil expansion vessel 20.

The antenna 85 is attached to an outer wall of the cell 55 and electrically connected to the sensor 70. In this exemplary embodiment, the antenna 85 is designed as a meandering transceiver Vivaldi antenna.

Opposite the underside 21 of the oil expansion vessel 20, there is an opening 24 at an upper end of the oil expansion vessel 20, which is closed with a pressure relief valve 50. The antenna 85, which is electrically connected to the sensor 70, is arranged above the opening 24.

The sensor 70 includes a baseband transmitter 71, a baseband receiver 72 and a digital backend 73, and is electrically connected to a computing device 90 via a cable. The baseband transmitter 71 generates pulsed excitation signals for the antenna 85, with reflected signals being forwarded to the baseband receiver 72. The digital backend 73 controls the sending and receiving of the signals by the baseband transmitter 71 and the baseband receiver 72. The sensor 70 is set up to send pulsed signals with a frequency of 1 Hz to 3000 GHz via the antenna 85 and to recieve. The system preferably operates in the ultra-broadband range, so that the sensor 70 is set up to send and receive signals with a frequency of 3.1 GHz to 10.6 GHz via the antenna 85. The sensor 70 sends and receives measurement signals via the antenna 85, with the help of which the quality of the oil in the oil expansion vessel 20 can be determined. This embodiment allows for advantageous portability, reducing the time required to check oil quality.

The computing device 90 is a laptop computer or any other type of computer that is set up to process and visualize the measured values measured by the sensor 70. In particular, the computing device 90 is set up to calculate values relating to the color, water content and/or acidity of the oil based on the measured values measured by the sensor 70. For example, a fast Fourier transform can be applied to the measurement data.

The oil transformer further comprises a temperature, gas and/or vibration sensor 65. The temperature, gas and/or vibration sensor 65 is arranged in the oil expansion vessel 20. The temperature, gas and/or vibration sensor 65 is set up to send measurement data to the sensor 70 and/or to the computing device 90. For this purpose, the temperature, gas and/or vibration sensor 65 can include a communication interface that enables communication with the sensor 70 and/or the computing device 90. The communication interface can be arranged at the opening 24 and, for example, provide a wired connection to the sensor 70. If the temperature, gas and/or vibration sensor 65 is designed as a gas sensor, it can be set up to detect abnormalities in the gas generated by the oil transformer. The sensor may also include additional sensor and electronic components that monitor regular operation and condition of the oil transformer.

In the presented exemplary embodiments, different features and functions of the present disclosure have been described separately from one another and in certain combinations. However, it is understood that all or some of these features and functions can be freely combined with one another, where this is not explicitly excluded.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 202008017356 U1 [0002]

Claims (13)

Oil transformer comprehensive a transformer tank (10), an oil expansion vessel (20), a flow channel (30) which connects the transformer tank (10) with a first opening (22) in the oil expansion vessel (20), a cell (55) for receiving oil (40), Means (57, 58) for conveying oil (40) from the oil expansion vessel (20) into the cell (55), an antenna (85) for applying a measurement signal to the oil (40) in the cell (55) and a sensor (70) electrically connected to the antenna (85) for measuring an oil quality of the oil transformer. oil transformer Claim 1 , wherein the sensor (70) is set up to send and receive signals with a frequency of 1 Hz to 3000 GHz via the antenna (85). Oil transformer according to one of the preceding claims, wherein the sensor (70) is set up to send and receive signals with a frequency of 3.1 GHz to 10.6 GHz via the antenna (85). Oil transformer according to one of the preceding claims, wherein the cell (55) is arranged within the oil expansion vessel (20) above a maximum oil level of the oil expansion vessel (20). Oil transformer according to one of the Claims 1 until 3 , wherein the cell (55) is arranged outside the oil expansion vessel (20) at a second opening (24) of the oil expansion vessel (20). oil transformer Claim 5 , wherein the second opening (24) is arranged at an upper end of the oil expansion vessel (20) and / or the second opening (24) comprises a valve (50). Oil transformer according to one of the preceding claims, wherein the antenna (85) is arranged on or in the cell (55). Oil transformer according to one of the preceding claims, wherein the antenna (85) is designed as a combined transmitting and receiving antenna. Oil transformer according to one of the preceding claims, wherein the sensor (70) comprises: an ultra-wideband baseband transmitter (71), an ultra-wideband baseband receiver (72) and a digital backend (73). Oil transformer according to one of the preceding claims, further comprising a computing device (90) connected to the sensor (70), the computing device (90) being set up to process and visualize the measured values measured by the sensor (70). oil transformer Claim 10 , wherein the computing device (90) is set up to calculate values relating to color, water content and / or acid content of oil in the oil expansion vessel (20) based on the measured values measured by the sensor (70). Oil transformer according to one of the preceding claims, further comprising a temperature, gas and/or vibration sensor (65) arranged on or in the oil expansion vessel (20). Oil transformer according to one of the preceding claims, wherein the means (57, 58) for conveying oil from the oil expansion vessel (20) into the cell (55) comprises a hose (57) and/or a pipe arranged at least partially in the oil expansion vessel (20). (57) having a first end extending into the oil (40) in the oil conservator (20) and a second end connected to the cell (55), and a pump (58) for pumping the oil (40 ) from the oil expansion vessel (20) into the cell (55).

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