Talking about the Principle and Comparison of Electronic Transformers
With the trend of the transformation of traditional substation to digital substation, the electronic transformers occupying an important position in the digital substation are getting more and more attention. This paper introduces the advantages, classification, comparison and current problems of electronic transformers in engineering applications.
With the rapid development of optical fiber sensing technology and optical fiber communication technology, the application of photoelectric technology in power systems is more and more extensive. Electronic transformers are one of them. The electronic transformer has many advantages such as small size, light weight, wide frequency response, no saturation, good anti-electromagnetic interference performance, no oil structure, reliable insulation, easy digitization and computer development, and will be widely used in digital substations. application.
The birth of electronic transformers is the inevitable result of the development of transformer sensing accuracy, transmission fiberization and output digitalization. Electronic transformers are one of the key equipment for digital substations. The sensing method has a great influence on the structural system of the electronic transformer. The optical principle of the electronic transformer has a simple structural system and is a passive electronic transformer. The electronic transformer of the principle of electromagnetic measurement is an active electronic transformer.
Advantages of 1 electronic transformer 1.1 High isolation and high isolation, high safety, excellent insulation performance, no iron core, eliminating magnetic saturation and ferromagnetic resonance. The measured signal and secondary coil of electromagnetic transformer Through the coupling of the iron core, the insulation structure is complicated, and its cost increases exponentially with the voltage level. The unconventional transformer transmits the high-voltage side signal to the secondary device through the optical fiber with good insulation performance, which greatly simplifies the insulation structure, and the higher the voltage level, the more obvious the cost-effective advantage. Unconventional transformers use optical cables instead of cables as signal transmission tools to achieve complete isolation of high and low voltages, without the short circuit of the secondary circuit of the voltage transformer or the secondary circuit of the current transformer to open the circuit to the equipment and human hazards, safety and Reliability is greatly improved.
Electromagnetic transformers inevitably have problems such as magnetic saturation and ferromagnetic resonance due to the use of iron cores. The unconventional transformer is intrinsically different from the traditional transformer. Generally, the core is not used for magnetic coupling, thus eliminating the phenomenon of magnetic saturation and ferromagnetic resonance, so that the transient response of the transformer is good and the stability is good. High reliability of system operation.
1.2 Anti-electromagnetic interference performance is good, there is no open circuit high voltage danger on the low voltage side. The secondary circuit of the electromagnetic current transformer cannot open the circuit, and there is danger of open circuit on the low voltage side. There is only an optical fiber between the high-voltage side and the low-voltage side of the unconventional transformer, and the signal is transmitted through the optical fiber. The high-voltage circuit is completely electrically isolated from the secondary circuit. The transformer has good anti-electromagnetic interference capability, and the low-voltage side has no open circuit. High voltage hazard.
1.3 Large dynamic range, high measurement accuracy, wide frequency response range The current flowing through the current transformer during normal operation of the grid is not large, but the short-circuit current is generally large, and the short-circuit current is larger as the grid capacity increases. Due to the magnetic saturation problem of the electromagnetic current transformer, it is difficult to achieve a wide range of measurements, and it is difficult for the same transformer to meet the needs of measurement and relay protection at the same time. Unconventional transformers have a wide dynamic range that meets both measurement and relay protection needs.
The frequency range of an unconventional transformer mainly depends on the relevant electronic circuit portion, and the frequency response range is wide. Unconventional transformers can measure harmonics on high-voltage power lines, and can also measure grid current transients, high-frequency large currents, and direct currents. Electromagnetic transformers are difficult to perform in this area.
1.4 Data transmission anti-interference ability Strong electromagnetic transformer transmits analog signals. Measurement, control and relay protection in power stations have traditionally transmitted electrical signals measured by electrical sensors to the control room via coaxial cables. When multiple different devices require signals from the same transformer, complex secondary wiring is required, which is inevitably disturbed by electromagnetic fields. The digital signal output by the photoelectric transformer can be conveniently used for data communication, and the photoelectric transformer and the device that needs to take the signal of the transformer can form a field bus network. Data sharing is achieved, which saves a large number of secondary cables. At the same time, the inherent anti-electromagnetic interference performance of fiber-optic sensors and fiber-optic communication networks shows unparalleled superiority in harsh power plant environments. Fiber-optic systems replace traditional electrical systems. The inevitable trend of future power station construction and transformation 1.5 There is no danger of flammable, explosive and other dangerous letters due to oil filling. The insulation structure of non-conventional transformers is relatively simple. Generally, oil is not used as the insulating medium, which will not cause fire and explosion. .
1.6 Small and lightweight Unconventional transformers have no iron core and their weight is much smaller than that of electromagnetic transformers of the same voltage class.
In summary, the unconventional transformers adapt to the needs of digital, intelligent and networked power systems with their superior performance, and have obvious economic and social benefits to ensure the security of increasingly large and complex power systems. Reliable operation and increased automation are of far-reaching significance.
2 Electronic transformer classification 2.1 Active electronic transformer Active electronic transformer uses the principle of electromagnetic induction to sense the measured signal, Rogowski coil for current transformer, resistor, capacitor or inductor voltage divider for voltage transformer . The high-voltage platform sensing head part of the active electronic transformer has an electronic circuit that requires power supply, and performs analog numerical sampling (ie, a remote module) on one platform, and transmits the digital signal to the secondary protection by using optical fiber transmission. , measurement and control and measurement systems.
Active electronic transformers can be divided into closed gas insulated combined electrical (GIS) type and independent type. GIS type electronic transformers are generally combined with current and voltage. The acquisition module is installed on the grounding shell of GIS. The insulation is solved by GIS, and the remote acquisition module is directly connected to the substation 220V/110V DC power supply at the ground potential. The acquisition unit of the independent electronic transformer is installed on the insulating ceramic column. Due to the insulation requirements, the power supply of the acquisition unit has various modes such as laser, small current transformer, voltage divider, and photovoltaic power supply. The actual engineering application generally adopts laser. The power supply, or the laser and the small current transformer cooperate with the power supply, that is, the power is supplied by the small current transformer when the line has a flow, and is supplied by the laser when there is no flow. For the independent electronic transformer, in order to reduce the cost and reduce the floor space, the combination is generally adopted, that is, the current transformer and the voltage transformer are installed on the same composite insulator, and the remote module simultaneously collects current and voltage signals, which can be used together. Power supply circuit 2.2 Passive electronic transformer Passive electronic transformer is also called optical transformer. Passive electronic current transformers use the Faraday magneto-optical effect to sense the signal under test. The sensor head is divided into two types: bulk glass and all-fiber. Passive electronic voltage transformers use the Pockels electro-optical effect or based on the inverse piezoelectric effect or the electro-induced contraction effect to induce the measured signal. Most of the optical voltage transformers studied now are based on the Pockels effect. The sensing head part of the passive electronic transformer does not require complicated power supply means, and the linearity of the whole system is better. The passive electronic transformer uses the optical fiber to transmit the primary current and voltage sensing signals to the main control room or the protection chamber for modulation and demodulation, and outputs digital signals to the MU for protection, measurement and control, and metering. The sensing head part of the passive electronic transformer is a relatively complicated optical system, which is susceptible to various environmental factors, such as temperature and vibration, which affect the practical process. For information, please visit: Transmission and Distribution Equipment Network
Key Technology active transformers 3 and Comparative passive transformer <br> <br> active electronic transformer power supply technology is that the maintainability and reliability of the distal end of the electronic module, the acquisition unit. Based on the operating experience of conventional transformers, maintenance of Rogowski coils and voltage dividers (resistors, capacitors or inductors) can be ignored. The GIS-type electronic transformer directly connects to the DC power supply of the substation, and does not require additional power supply. The acquisition unit is installed on the grounding shell that is closely connected to the earth. This method has strong anti-interference ability, convenient replacement and maintenance, and the system does not need a system power failure for abnormal processing of the acquisition unit. For the independent electronic transformer, the power supply and the remote module on the high-voltage platform work for a long time in the harsh environment where the high and low temperature are frequently alternated, and the service life is far less than that of the protection and control device installed in the main control room or the protection chamber. It is necessary to accumulate actual engineering experience; in addition, when the power supply or remote module is abnormal, needs maintenance or replacement, a system power failure processing is required. Information Sources:
The key technologies of passive electronic transformers are the stability of optical sensing materials, the assembly technology of the sensing head, the modulation and demodulation of weak signals, the influence of temperature on accuracy, the influence of vibration on accuracy, and the stability of long-term operation. However, since the electronic circuit parts of the passive electronic transformer are installed in the main control room or the protection chamber, the operating conditions are superior, and the replacement and maintenance are convenient. The application of active or passive electronic transformers greatly reduces the floor space and reduces the secondary cable connection of traditional transformers, which is the development direction of transformers. Passive electronic transformers are ideal for independent installation of high reliability and easy maintenance.
The main problem of the main problems <br> <br> 4 electronic transformer electronic transformer in engineering application exists: Because the sensor needs to be powered, long-term supply of high-power laser light can affect the life of the device The Rogowski coil output signal has a strong correlation with its structure. Temperature changes can cause structural changes and affect the accuracy of electronic circuit measurement.
The main problem in the application of photoelectric transformers is that the change of temperature will cause the change of the optical path system to cause the interference effect of the crystal in addition to the electro-optic effect, such as the bounce effect and the thermo-optic effect, resulting in the operation of the optical voltage sensor in the insulator. The stability is weakened. The influence of temperature on the measurement error of photoelectric transformers has been a hot topic. In practical applications, the influence of measurement errors caused by temperature changes should improve the anti-interference ability of optical systems (such as photodiodes). For example, in the research of improving the temperature stability, the temperature control method has been paid attention to by domestic and foreign scholars, such as a light source with good temperature stability and low wavelength drift, and a purely and repeatedly pulled electro-optic crystal. Dual optical path temperature compensation method, dual crystal temperature compensation, hardware circuit compensation and software compensation. In addition, the influence of the birefringence effect of the magneto-optical material on the measurement accuracy of the photoelectric current transformer is due to the birefringence effect of the magneto-optical material, so that the linearly polarized light of the magneto-optical medium is converted into elliptically polarized light, and the result is: The change of the light intensity outputted by the polarizer is not proportional to the current to be measured, which makes the sensitivity of the photoelectric current transformer unstable, thereby reducing the measurement accuracy of the photoelectric current transformer.
With the rapid development of optical fiber sensing technology and optical fiber communication technology, the application of photoelectric technology in power systems is more and more extensive. Electronic transformers are one of them. The electronic transformer has many advantages such as small size, light weight, wide frequency response, no saturation, good anti-electromagnetic interference performance, no oil structure, reliable insulation, easy digitization and computer development, and will be widely used in digital substations. application.
The birth of electronic transformers is the inevitable result of the development of transformer sensing accuracy, transmission fiberization and output digitalization. Electronic transformers are one of the key equipment for digital substations. The sensing method has a great influence on the structural system of the electronic transformer. The optical principle of the electronic transformer has a simple structural system and is a passive electronic transformer. The electronic transformer of the principle of electromagnetic measurement is an active electronic transformer.
Advantages of 1 electronic transformer 1.1 High isolation and high isolation, high safety, excellent insulation performance, no iron core, eliminating magnetic saturation and ferromagnetic resonance. The measured signal and secondary coil of electromagnetic transformer Through the coupling of the iron core, the insulation structure is complicated, and its cost increases exponentially with the voltage level. The unconventional transformer transmits the high-voltage side signal to the secondary device through the optical fiber with good insulation performance, which greatly simplifies the insulation structure, and the higher the voltage level, the more obvious the cost-effective advantage. Unconventional transformers use optical cables instead of cables as signal transmission tools to achieve complete isolation of high and low voltages, without the short circuit of the secondary circuit of the voltage transformer or the secondary circuit of the current transformer to open the circuit to the equipment and human hazards, safety and Reliability is greatly improved.
Electromagnetic transformers inevitably have problems such as magnetic saturation and ferromagnetic resonance due to the use of iron cores. The unconventional transformer is intrinsically different from the traditional transformer. Generally, the core is not used for magnetic coupling, thus eliminating the phenomenon of magnetic saturation and ferromagnetic resonance, so that the transient response of the transformer is good and the stability is good. High reliability of system operation.
1.2 Anti-electromagnetic interference performance is good, there is no open circuit high voltage danger on the low voltage side. The secondary circuit of the electromagnetic current transformer cannot open the circuit, and there is danger of open circuit on the low voltage side. There is only an optical fiber between the high-voltage side and the low-voltage side of the unconventional transformer, and the signal is transmitted through the optical fiber. The high-voltage circuit is completely electrically isolated from the secondary circuit. The transformer has good anti-electromagnetic interference capability, and the low-voltage side has no open circuit. High voltage hazard.
1.3 Large dynamic range, high measurement accuracy, wide frequency response range The current flowing through the current transformer during normal operation of the grid is not large, but the short-circuit current is generally large, and the short-circuit current is larger as the grid capacity increases. Due to the magnetic saturation problem of the electromagnetic current transformer, it is difficult to achieve a wide range of measurements, and it is difficult for the same transformer to meet the needs of measurement and relay protection at the same time. Unconventional transformers have a wide dynamic range that meets both measurement and relay protection needs.
The frequency range of an unconventional transformer mainly depends on the relevant electronic circuit portion, and the frequency response range is wide. Unconventional transformers can measure harmonics on high-voltage power lines, and can also measure grid current transients, high-frequency large currents, and direct currents. Electromagnetic transformers are difficult to perform in this area.
1.4 Data transmission anti-interference ability Strong electromagnetic transformer transmits analog signals. Measurement, control and relay protection in power stations have traditionally transmitted electrical signals measured by electrical sensors to the control room via coaxial cables. When multiple different devices require signals from the same transformer, complex secondary wiring is required, which is inevitably disturbed by electromagnetic fields. The digital signal output by the photoelectric transformer can be conveniently used for data communication, and the photoelectric transformer and the device that needs to take the signal of the transformer can form a field bus network. Data sharing is achieved, which saves a large number of secondary cables. At the same time, the inherent anti-electromagnetic interference performance of fiber-optic sensors and fiber-optic communication networks shows unparalleled superiority in harsh power plant environments. Fiber-optic systems replace traditional electrical systems. The inevitable trend of future power station construction and transformation 1.5 There is no danger of flammable, explosive and other dangerous letters due to oil filling. The insulation structure of non-conventional transformers is relatively simple. Generally, oil is not used as the insulating medium, which will not cause fire and explosion. .
1.6 Small and lightweight Unconventional transformers have no iron core and their weight is much smaller than that of electromagnetic transformers of the same voltage class.
In summary, the unconventional transformers adapt to the needs of digital, intelligent and networked power systems with their superior performance, and have obvious economic and social benefits to ensure the security of increasingly large and complex power systems. Reliable operation and increased automation are of far-reaching significance.
2 Electronic transformer classification 2.1 Active electronic transformer Active electronic transformer uses the principle of electromagnetic induction to sense the measured signal, Rogowski coil for current transformer, resistor, capacitor or inductor voltage divider for voltage transformer . The high-voltage platform sensing head part of the active electronic transformer has an electronic circuit that requires power supply, and performs analog numerical sampling (ie, a remote module) on one platform, and transmits the digital signal to the secondary protection by using optical fiber transmission. , measurement and control and measurement systems.
Active electronic transformers can be divided into closed gas insulated combined electrical (GIS) type and independent type. GIS type electronic transformers are generally combined with current and voltage. The acquisition module is installed on the grounding shell of GIS. The insulation is solved by GIS, and the remote acquisition module is directly connected to the substation 220V/110V DC power supply at the ground potential. The acquisition unit of the independent electronic transformer is installed on the insulating ceramic column. Due to the insulation requirements, the power supply of the acquisition unit has various modes such as laser, small current transformer, voltage divider, and photovoltaic power supply. The actual engineering application generally adopts laser. The power supply, or the laser and the small current transformer cooperate with the power supply, that is, the power is supplied by the small current transformer when the line has a flow, and is supplied by the laser when there is no flow. For the independent electronic transformer, in order to reduce the cost and reduce the floor space, the combination is generally adopted, that is, the current transformer and the voltage transformer are installed on the same composite insulator, and the remote module simultaneously collects current and voltage signals, which can be used together. Power supply circuit 2.2 Passive electronic transformer Passive electronic transformer is also called optical transformer. Passive electronic current transformers use the Faraday magneto-optical effect to sense the signal under test. The sensor head is divided into two types: bulk glass and all-fiber. Passive electronic voltage transformers use the Pockels electro-optical effect or based on the inverse piezoelectric effect or the electro-induced contraction effect to induce the measured signal. Most of the optical voltage transformers studied now are based on the Pockels effect. The sensing head part of the passive electronic transformer does not require complicated power supply means, and the linearity of the whole system is better. The passive electronic transformer uses the optical fiber to transmit the primary current and voltage sensing signals to the main control room or the protection chamber for modulation and demodulation, and outputs digital signals to the MU for protection, measurement and control, and metering. The sensing head part of the passive electronic transformer is a relatively complicated optical system, which is susceptible to various environmental factors, such as temperature and vibration, which affect the practical process. For information, please visit: Transmission and Distribution Equipment Network
Key Technology active transformers 3 and Comparative passive transformer <br> <br> active electronic transformer power supply technology is that the maintainability and reliability of the distal end of the electronic module, the acquisition unit. Based on the operating experience of conventional transformers, maintenance of Rogowski coils and voltage dividers (resistors, capacitors or inductors) can be ignored. The GIS-type electronic transformer directly connects to the DC power supply of the substation, and does not require additional power supply. The acquisition unit is installed on the grounding shell that is closely connected to the earth. This method has strong anti-interference ability, convenient replacement and maintenance, and the system does not need a system power failure for abnormal processing of the acquisition unit. For the independent electronic transformer, the power supply and the remote module on the high-voltage platform work for a long time in the harsh environment where the high and low temperature are frequently alternated, and the service life is far less than that of the protection and control device installed in the main control room or the protection chamber. It is necessary to accumulate actual engineering experience; in addition, when the power supply or remote module is abnormal, needs maintenance or replacement, a system power failure processing is required. Information Sources:
The key technologies of passive electronic transformers are the stability of optical sensing materials, the assembly technology of the sensing head, the modulation and demodulation of weak signals, the influence of temperature on accuracy, the influence of vibration on accuracy, and the stability of long-term operation. However, since the electronic circuit parts of the passive electronic transformer are installed in the main control room or the protection chamber, the operating conditions are superior, and the replacement and maintenance are convenient. The application of active or passive electronic transformers greatly reduces the floor space and reduces the secondary cable connection of traditional transformers, which is the development direction of transformers. Passive electronic transformers are ideal for independent installation of high reliability and easy maintenance.
The main problem of the main problems <br> <br> 4 electronic transformer electronic transformer in engineering application exists: Because the sensor needs to be powered, long-term supply of high-power laser light can affect the life of the device The Rogowski coil output signal has a strong correlation with its structure. Temperature changes can cause structural changes and affect the accuracy of electronic circuit measurement.
The main problem in the application of photoelectric transformers is that the change of temperature will cause the change of the optical path system to cause the interference effect of the crystal in addition to the electro-optic effect, such as the bounce effect and the thermo-optic effect, resulting in the operation of the optical voltage sensor in the insulator. The stability is weakened. The influence of temperature on the measurement error of photoelectric transformers has been a hot topic. In practical applications, the influence of measurement errors caused by temperature changes should improve the anti-interference ability of optical systems (such as photodiodes). For example, in the research of improving the temperature stability, the temperature control method has been paid attention to by domestic and foreign scholars, such as a light source with good temperature stability and low wavelength drift, and a purely and repeatedly pulled electro-optic crystal. Dual optical path temperature compensation method, dual crystal temperature compensation, hardware circuit compensation and software compensation. In addition, the influence of the birefringence effect of the magneto-optical material on the measurement accuracy of the photoelectric current transformer is due to the birefringence effect of the magneto-optical material, so that the linearly polarized light of the magneto-optical medium is converted into elliptically polarized light, and the result is: The change of the light intensity outputted by the polarizer is not proportional to the current to be measured, which makes the sensitivity of the photoelectric current transformer unstable, thereby reducing the measurement accuracy of the photoelectric current transformer.
Long distance LiDAR sensor IT03M series are particularly easy to communication thanks to their fixed connector, which can be plugged it up and off by yourself. Voltage is wider from 3.3v before to 3.6v. Low power consumption feature makes it beceome a very competitive, high performance-price ratio, long range Laser Distance Sensor.
Highlights:
> Measurement frequency: 100 Hz (Max 200 Hz)
> High temperatures: -10~+50℃
> UART output
> Connector design: easy to use
Parameters of IT03M:
|
Accuracy |
+/-5cm@ 0.1~2.5m |
|
Measuring Unit |
cm |
|
Measuring Range (without Reflection) |
0.1-15m |
|
Measuring Time |
0.1~3 seconds |
|
Measuring Frequency |
100 Hz |
|
Laser Class |
Class II |
|
Laser Type |
650nm, <1mw, red |
|
Weight |
About 10g |
|
Voltage |
DC2.5V~+3.5V |
|
Serial Level |
TTL 3.3V |
|
Size |
50*26*13mm |
|
Operating Temperature |
0-40 ℃ (32-104 ℉ ) |
|
Storage Temperature |
-25~60 ℃ (-13~140 ℉) |
Speed Laser Sensor,Long Range Lidar,Long Range 3D Lidar,Long Range Radar Sensor
Chengdu JRT Meter Technology Co., Ltd , https://www.jrt-measure.com