JP2001013170A - Transformer for meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transformer for a meter simultaneously realizing simplification and rationalization of a system structure, and high precision by temperature compensation. SOLUTION: In this transformer, an electronic circuit board 3 is disposed near a capacitive divider 2 and a Rogowskii coil 1 that are a detection means, while a temperature sensor 4 is provided on the electronic circuit board 3. The electronic circuit board 3 is configured such that temperature characteristics of the Rogowskii coil 1 and the capacitive divider 2 and compensated on the basis of an output of the temperature sensor 4 to keep a transformation ratio constant. A high-order system 15 and the electronic circuit board 3 are connected with an optical communication cable 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an instrument transformer for transforming a primary current or a primary voltage of a transformer, and more particularly to an instrument transformer having an electronic circuit board for transmitting current and voltage information to a host system. It is about.

[0002]

2. Description of the Related Art Generally, a transformer for an instrument (general term for an instrument current transformer and an instrument transformer) is incorporated in a substation equipment. An instrument transformer transforms the primary voltage or primary current of substation equipment into a secondary voltage or secondary current of a level that is compatible with the host system. The purpose is to protect substation equipment when a large current flows.

As a typical conventional example of such a transformer for an instrument, there is known a transformer mainly composed of an iron core and a winding, which transforms a primary voltage or a primary current by utilizing an electromagnetic induction effect. In this instrument transformer, the cross-sectional area of the iron core or winding is made larger than that of a general transformer so that the accuracy can be maintained even if the load is increased.
There is an advantage that no special additional device is required when the host system is an analog type and the power consumption of the input section is large. However, on the other hand, since the iron core is used, there is a possibility that adverse effects due to ferroresonance and magnetic saturation phenomenon may occur. In recent years, digitalization of higher-level systems has progressed, and the load required for instrument transformers has been reduced, and the importance of the above advantages has been decreasing. In addition, from the viewpoints of accuracy and system rationalization, it is desired to directly transmit current and voltage information from an instrument transformer in the form of digital data.

[0004] Recently, instead of using a core, an instrument that combines detection means for measuring the primary current or primary voltage of a substation equipment and an electronic circuit board for transmitting the output of the detection means to a host system. Transformers have been developed. Specific examples of the detection means include a current sensor such as a Rogowski coil, a voltage sensor such as a capacitive voltage divider, and an optical element having an optical effect such as the Faraday effect or the Pockels effect. According to the instrument transformer of this type, it is possible to eliminate the adverse effects due to ferroresonance and magnetic saturation,
It is possible to directly transmit current and voltage information in the form of digital data, which is extremely advantageous in improving accuracy and rationalizing the system.

[0005] Here, a conventional example of an instrument transformer using a combination of a detecting means and an electronic circuit board will be described in detail with reference to the block diagram of FIG. As shown in the figure, a tank 11 is provided in the instrument transformer 30, and a high-voltage conductor 12 is provided in the tank 11. A Rogowski coil 1 and a capacitive voltage divider 2 as detection means are provided so as to surround the high voltage conductor 12. The Rogowski coil 1 is a current sensor that outputs a voltage proportional to the time change of the primary current flowing through the high-voltage conductor 12, and the capacitive voltage divider 2 outputs a voltage proportional to the primary voltage applied to the high-voltage conductor 12. It is a voltage sensor.

Further, an upper system 15 is installed independently of the instrument transformer 30. The electronic circuit board 3 is disposed inside the host system 15, and a constant voltage power supply 27 is connected to the electronic circuit board 3 via a power cable 28. Power is supplied to the electronic circuit board 3 from the constant voltage power supply 27. Further, one ends of connection cables 5 and 6 are connected to the Rogowski coil 1 and the capacity voltage divider 2, respectively, and the other ends of these connection cables 5 and 6 are connected to the electronic circuit board 3 in the host system 15. Have been. That is, the Rogowski coil 1 and the capacitive voltage divider 2 are connected to the electronic circuit board 3 via the connection cables 5 and 6.

In the above-described instrument transformer, the temperature characteristic of the detecting means is a major factor in determining the accuracy of the entire instrument transformer. For example, in the case of the Rogowski coil 1, the output changes due to a change in coil cross-sectional area due to thermal expansion and contraction of the winding and the winding frame, a change in winding resistance due to temperature, and the like. In the case of the capacitive voltage divider 2, the output also changes due to changes in electrode dimensions due to thermal expansion and contraction, changes in the dielectric constant of the dielectric due to temperature, and the like. Furthermore, even when an optical element is used, the output is affected by the magnitude of the optical effect changing with temperature. That is, the output of the detecting means may change with the change of the ambient temperature of the detecting means, and the transformation ratio (the transformation ratio or the current transformation ratio) may change. Therefore, it is essential to compensate for the temperature characteristics of the detecting means in a measuring and power transformer for an instrument that requires high accuracy.

In the instrument transformer 30 shown in FIG. 6, a temperature sensor 4 for measuring the ambient temperature is installed on the outer wall of the tank 11, and the temperature sensor 4 and the electronic circuit board 3 are connected via a connection cable 7. It is connected. In the instrument transformer 30 having such a configuration, the temperature sensor 4 is connected to the tank 11.
The ambient temperature is measured and output to the electronic circuit board 3 via the connection cable 7. In the electronic circuit board 3, an operation is performed from a relational expression between the temperature previously obtained by an experiment or the like and the outputs of the Rogowski coil 1 and the capacity voltage divider 2, and the Rogowski coil 1 and the capacity are calculated based on the calculation result. The temperature characteristic of the voltage divider 2 is compensated to keep the conversion ratio constant. Therefore, even if the temperature around the Rogowski coil 1 and the capacity voltage divider 2 changes, the transformation ratio does not change, and the instrument transformer 30 can ensure excellent accuracy.

However, in the above conventional example, three connection cables 5, 6, 7 for the Rogowski coil 1, for the capacity voltage divider 2, and for the temperature sensor 4 are required. Reference numeral 7 denotes a long wiring to the electronic circuit board 3 in the host system 15 which is separated from the instrument transformer 30. Therefore, the amount of cable wiring has increased. As a result, not only does the system become complicated, but also there is a problem that the system is easily affected by noise.

[0010] In view of such circumstances, attempts have been made to simplify and rationalize the system and reduce the influence of connection cables. For example, G. Schett et al. (ABB High Volta
geTechnologies Ltd.), CIGRE Session-1996
34-104 "The IntelligentGIS-A Fundamental Change
in the Combination of Primary and SecondaryEquipm
ent ". FIG. 7 is a block diagram showing a conventional example of an instrument transformer based on the proposal of the above-mentioned paper.

In the instrument transformer 31 shown in FIG.
An electronic circuit case 13 is provided outside the tank 11 in the vicinity of the Rogowski coil 1 and the capacitive voltage divider 2, and the electronic circuit board 3 for sensor output measurement and communication is housed inside. There is a feature. The output of the Rogowski coil 1 is connected to the electronic circuit board 3 by a connection cable 5, and the output of the capacitive voltage divider 2 is connected to the electronic circuit board 3 by a connection cable 6. Further, a communication optical cable 10 for digital data transmission is provided on the electronic circuit board 3.
Is connected. On the other hand, an upper electronic circuit board 16 and a constant voltage power supply 27 are arranged in the upper system 15. The constant voltage power supply 27 is connected to the electronic circuit board 3 by a power cable 28, and the upper electronic circuit board 16 is connected to the electronic circuit board 3 of the instrument transformer 30 by the communication optical cable 10.

In the instrument transformer 31 as described above, the length of the connecting cables 5 and 6 between the Rogowski coil 1 and the capacitive voltage divider 2 and the electronic circuit board 3 is minimized, and the instrument transformer 31 is provided. Only means for connecting the communication system 10 and the host system 15 is the communication optical cable 10 and the power cable 28. Therefore, the wiring amount of the connection cable can be significantly reduced, and the configuration of the entire system including the instrument transformer 31 and the host system 15 can be simplified and rationalized. It is also possible to reduce the influence of the connection cable on the sensor output.

[0013]

However, the transformer for an instrument based on the proposal of the above-mentioned article does not describe a method for compensating the temperature characteristic of the detecting means such as a Rogowski coil and a capacitive voltage divider. If the ambient temperature of the means fluctuates, there is a possibility that the transformation ratio of the instrument transformer changes and accuracy deteriorates. In addition, there is a high demand for instrument transformers that combine the detection means and the electronic circuit board, as digitization of higher-level systems is in progress, and further simplification and rationalization of the system configuration and longer life are required. Have been.

The present invention has been proposed to solve the above-mentioned problems, and the main objects of the present invention are to simultaneously simplify and rationalize the system configuration, reduce the influence of the connecting cable, and increase the accuracy by temperature compensation. It is an object of the present invention to provide a realized instrument transformer.

Another object of the present invention is to realize further simplification and rationalization of the system configuration, and further to extension of the service life.

[0016]

To achieve the above object, the present invention provides a detecting means for measuring a primary current or a primary voltage of a substation equipment, and an electronic circuit for transmitting an output of the detecting means to a host system. An instrument transformer including a substrate has the following technical features.

The invention according to claim 1 is characterized in that a temperature sensor for measuring an ambient temperature is provided near the detecting means. In the first aspect of the present invention, since the electronic circuit board connected to the detecting means is provided not on the host system side but on the instrument transformer side, the connecting cable connecting the detecting means and the electronic circuit board is shortened. Thus, the system configuration can be simplified and rationalized, and the influence of the connection cable can be reduced. At the same time, since the temperature sensor measures the temperature around the detecting means, the temperature characteristic of the detecting means can be compensated based on the output of the temperature sensor, and the transformation ratio of the instrument transformer can be kept constant. .

According to a second aspect of the present invention, in the instrument transformer according to the first aspect, the electronic circuit board is arranged near the detecting means, and the temperature sensor is installed on the electronic circuit board. It is characterized by. Claim 2
According to the invention described above, since the electronic circuit board is disposed near the detecting means, the temperature measured by the temperature sensor on the electronic circuit board can be regarded as substantially equal to the temperature around the detecting means. it can. Therefore, as in the case of the instrument transformer according to the first aspect, the temperature characteristics of the detecting means can be compensated, and high accuracy can be achieved. In addition, since the temperature sensor is installed on the electronic circuit board, there is no need for a connection cable to connect the temperature sensor to the host system, further reducing the amount of cable wiring, simplifying and streamlining the system configuration, and connecting cables. Can be reduced.

The third aspect of the present invention is the first or second aspect.
The above described transformer for an instrument is characterized in that the electronic circuit board is configured to compensate the temperature characteristic of the detecting means based on the output of the temperature sensor and keep the transformation ratio constant. According to the third aspect of the present invention, the electronic circuit board itself can perform the arithmetic processing for compensating the temperature characteristic of the detecting means based on the output of the temperature sensor. Therefore, it is not necessary to transmit the output of the temperature sensor to the host system, and the amount of communication to the host system and the amount of calculation in the host system are reduced. Therefore, the system configuration can be further simplified and rationalized.

The invention described in claim 4 is the invention according to claim 1 or 2
The above-described instrument transformer is characterized in that the electronic circuit board is configured to transmit the output of the temperature sensor to the host system together with the output of the detecting means. According to the fourth aspect of the present invention, the electronic circuit board transmits the output of the detecting means and the output of the temperature sensor to the host system. Do not do. Therefore, the power consumption of the electronic circuit board can be reduced and the life can be extended.

The invention according to claim 5 is the invention according to claims 1, 2, and 3.
Or the instrument transformer according to 4, wherein the host system and the electronic circuit board are connected by an optical cable. According to the fifth aspect of the invention,
Since the electronic circuit board and the host system are connected by the optical cable, excellent measurement accuracy can be exhibited without being affected by noise. Moreover, both can be completely electrically insulated. Therefore, the restriction on the arrangement of the electronic circuit board can be relaxed, and the electronic circuit board can be arranged near the high-voltage conductor, and the length of the connection cable connecting the electronic circuit board and the detecting means is extremely reduced. , The configuration can be simplified.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. The same members as those in the conventional example shown in FIGS. 6 and 7 are denoted by the same reference numerals, and description thereof will be omitted.

(1) First Embodiment—Corresponding to Claims 1, 2, 3, and 5 [Structure] A first embodiment will be described with reference to FIGS. 1 and 2. The first embodiment is described in claims 1 and 2.
FIG. 1 is a block diagram showing a configuration of the first embodiment, and FIG. 2 is an electronic circuit board 3.
FIG. 3 is a block diagram showing a circuit configuration of FIG.

Instrument transformer 3 according to the first embodiment
In the electronic circuit board 2, an electronic circuit board 3 is disposed near the Rogowski coil 1 and the capacitive voltage divider 2, which are detection means, and a temperature sensor 4 is provided on the electronic circuit board 3.
Further, the electronic circuit board 3 is configured to compensate the temperature characteristics of the Rogowski coil 1 and the capacitive voltage divider 2 based on the output of the temperature sensor 4 to keep the transformation ratio constant. Further, the host system 15 and the electronic circuit board 3 are connected by the communication optical cable 10.

In general, a plurality of instrument transformers 32 are connected to the host system 15, and each instrument transformer 3
2 to operate at high speed by collecting data and comparing and judging. The power of the electronic circuit board 3 is supplied by a power cable 28 in the host system 15.

Next, the signal flow in the electronic circuit board 3 will be described with reference to the block diagram of FIG. The electronic circuit board 3 is provided with a low-pass filter 21, an analog-digital converter 22, a processing device 23, and an optical link 24. Output signals from the Rogowski coil 1, the capacitive voltage divider 2 and the temperature sensor 4 are first passed through a low-pass filter 2
1 and then passed through an analog-to-digital converter 22. After that, it is guided to the processing device 23. The high-frequency noise included in the output voltage signal is removed by the low-pass filter 21, and the output voltage signal, which is an analog signal, is converted into a digital signal by the analog-digital converter 22.

The digital signal output from the analog-digital converter 22 is input to a processing unit 23. In the processor 23, the output of the Rogowski coil 1 is integrated,
While the primary current is restored, a correction operation for keeping the metamorphic ratio constant is performed based on the relational expression between the temperature and the output, which is obtained in advance through experiments and the like, and the ambient temperature measured by the temperature sensor 4. The temperature characteristics of the Rogowski coil 1 and the capacitive voltage divider 2 are compensated. The digital signal after the correction operation is transmitted to the host system 1
5 after being converted into a serial output signal conforming to the transmission procedure for the communication optical cable 10 via the optical link 24.
To the host system 15.

[Operation and Effect] According to the first embodiment having the above configuration, the following operation and effect can be obtained. First, since the electronic circuit board 3 is disposed near the Rogowski coil 1 and the capacitive voltage divider 2, the temperature measured by the temperature sensor 4 on the electronic circuit board 3 can be used for the Rogowski coil 1 and the capacitive voltage divider 2. Ambient temperature. Therefore, based on the temperature measured by the temperature sensor 4, the electronic circuit board 3 can perform a correction operation for compensating for the temperature characteristics of the Rogowski coil 1 and the capacitive voltage divider 2 and keeping the current conversion ratio constant. As a result, even if the ambient temperature of the Rogowski coil 1 and the capacity voltage divider 2 greatly fluctuates, deterioration of the measurement accuracy of the instrument transformer 32 can be reliably prevented, and excellent measurement accuracy can be maintained. .

Second, the temperature sensor 4 is mounted on the electronic circuit board 3.
Is installed, a connection cable for connecting the temperature sensor 4 and the host system 15 is unnecessary, and the amount of cable wiring can be reduced. Therefore, simplification of the system configuration
The rationalization and the effect of the connection cable can be further reduced.

Third, since the electronic circuit board 3 on the instrument transformer 32 performs an operation relating to temperature compensation, it is not necessary to transmit temperature information to the host system 15 and the amount of communication is reduced. be able to. Therefore, the amount of calculation in the host system 15 is also reduced, and simplification and rationalization of the system configuration can be achieved.

Fourth, the electronic circuit board 3 and the host system 1
5 is connected by the optical cable 10, so that both can be electrically insulated completely. Therefore, restrictions on the arrangement of the electronic circuit board 3 are relaxed, and the electronic circuit board 3 can be arranged near the high-voltage conductor 12. Therefore, the connecting cables 5 and 6 can be extremely short, and the configuration can be simplified. Further, since the signal is transmitted by the communication optical cable 10, the measurement is not affected by noise, and excellent measurement accuracy can be obtained.

(2) Second Embodiment Corresponding to Claims 4 and 5 [Configuration] A second embodiment corresponding to the inventions described in claims 4 and 5 will be described with reference to FIGS. 3 and 4. explain. 3 and 4, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. Second
The instrument transformer according to the embodiment of the present invention is mainly used in an air substation.

FIG. 3 is a block diagram showing the configuration of the second embodiment. Instrument transformer 3 according to the second embodiment
In 3, the electronic circuit case 13 is supported by an insulating support 40, and is installed at a high potential location near the aerial high-voltage conductor 14. Further, the electronic circuit board 3 housed in the electronic circuit case 13 is connected to the upper electronic circuit board 16 by the communication optical cable 10 as in the first embodiment. Further, a photoelectric conversion device 25 is provided on the electronic circuit board 3, to which one end of a power supply optical cable 26 is connected. The other end of the power supply optical cable 26 is connected to the upper electronic circuit board 16 in the upper system 15.

FIG. 4 is a block diagram showing the circuit configuration of the electronic circuit board 3 and the flow of signals therebetween. In the processing device 23, the output of the Rogowski coil 1 is integrated to restore the primary current, and the current, voltage, and temperature information is not corrected and converted into an optical signal via the optical link 24 and the communication optical cable 10. The information is transmitted to the host system 15. Then, in the upper electronic circuit board 16 in the upper system 15, the calculation of the temperature compensation is performed. The power of the electronic circuit board 3 is supplied by the photoelectric conversion device 25 connected to the power supply optical cable 26.

[Functions and Effects] The functions and effects of the second embodiment having the above configuration are as follows. That is, since the electronic circuit board 3 and the host system 15 are connected only by the communication optical cable 10 and the power supply optical cable 26, they are completely electrically insulated. Therefore, the restriction on the arrangement of the electronic circuit board 3 is relaxed, and it is easy to arrange the electronic circuit board 3 in the vicinity of the airborne high-voltage conductor 14. Further, since the signal is transmitted by the communication optical cable 10, the measurement accuracy is not reduced by the transmission to the host system 15, and the signal is not affected by noise. Further, since the operation of temperature compensation is performed in the upper electronic circuit board 16 in the upper system 15, the operation speed of the processing device 23 in the electronic circuit board 3 can be relatively low. Therefore, the power consumption of the electronic circuit board 3 can be reduced. Therefore, the intensity of the power supply light can be reduced, and the life of the electronic circuit board 3 (more specifically, the optical element or the like on the electronic circuit board 3) can be extended.

(3) Other Embodiments The present invention is not limited to the above-described embodiment. For example, in an instrument transformer 34 shown in FIG. A temperature sensor 4b is arranged in close proximity to the capacitive voltage divider 2 with the sensor 4a. At this time, the output parts of the temperature sensors 4a, 4b are connected to the electronic circuit board 3 by a very short connection cable 7. According to such an embodiment as well, it is possible to obtain operational effects such as simplification and rationalization of the configuration and higher accuracy, as in the above embodiment. In addition, the target substation equipment includes gas insulated switchgear, air switchgear,
It is widely applicable to transformers and the like. Further, as the primary current or primary voltage detecting means, not only the Rogowski coil 1 and the capacitive voltage divider 2 but also various sensors based on various principles can be used. Various devices such as a digital signal processor and a digital signal processor can be applied.

[0037]

As described above, according to the instrument transformer of the present invention, an electronic circuit board for transmitting an output of a detecting means for measuring a primary current or a primary voltage of a substation apparatus to a host system is provided. Extremely simple configuration, such as installing a temperature sensor that measures the ambient temperature in close proximity to the detection means, reduces the amount of connecting cables and simplifies and rationalizes the overall system configuration, while at the same time greatly changing the ambient temperature. Even if the temperature characteristic is compensated for, the current transformation ratio can be kept constant, and high accuracy can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration and a signal flow of the electronic circuit board according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a second embodiment of the present invention.

FIG. 4 is a block diagram showing a circuit configuration and a signal flow of an electronic circuit board according to a second embodiment of the present invention.

FIG. 5 is a block diagram of another embodiment of the present invention.

FIG. 6 is a block diagram of a conventional transformer for temperature compensation.

FIG. 7 is a block diagram of an instrument transformer compatible with digital data transmission.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rogowski coil 2 ... Capacitance voltage divider 3 ... Electronic circuit board 4, 4a, 4b ... Temperature sensor 5, 6, 7 ... Connection cable 10 ... Communication optical cable 11 ... Tank 12 ... High voltage conductor 13 ... Electronic circuit case 14 ... Medium and high voltage conductors 15 ... Host system 16 ... Host electronic circuit board 21 ... Low-pass filter 22 ... Analog-to-digital converter 23 ... Processor 24 ... Optical link 25 ... Photoelectric converter 26 ... Power supply optical cable 27 ... Constant voltage Power supply 28 ... Power supply cable 30, 31, 32, 33, 34 ... Instrument transformer 40 ... Insulating support

Claims (5)

[Claims] 1. An instrument transformer provided with a detecting means for measuring a primary current or a primary voltage of a substation equipment and an electronic circuit board for transmitting an output of the detecting means to a host system. And a temperature sensor for measuring the ambient temperature. 2. An instrument transformer according to claim 1, wherein said electronic circuit board is arranged near said detecting means, and said temperature sensor is mounted on said electronic circuit board. 3. The electronic circuit board according to claim 1, wherein the electronic circuit board is configured to compensate a temperature characteristic of the detecting means based on an output of the temperature sensor to maintain a constant transformation ratio. An instrument transformer as described. 4. The instrument transformer according to claim 1, wherein the electronic circuit board is configured to transmit the output of the temperature sensor to the host system together with the output of the detection means. . 5. The instrument transformer according to claim 1, wherein the host system and the electronic circuit board are connected by an optical cable.