JPH07104012A - Signal detecting device for power distribution line - Google Patents

Abstract

PURPOSE:To provide a signal detecting device for power distribution line, which can accurately transmit the line signal to a place separated from the power distribution line and which can utilize an existing detector at a low cost and which can obtain a power source for a signal processing unit necessary for transmission with an easy means. CONSTITUTION:High voltage of a power distribution line 1 is lowered by a ceramic capacitor, and furthermore, lowered by a power source transformer to a low voltage for operating a signal processing unit 3a, and furthermore, rectified to the direct current by a rectifier, and supplied to the signal processing unit 3a. The line signal detected from the line 1 as the analog electric signal by a detector 2 is converted to the digital light signal by the signal processing unit 3a, and transmitted to a place separated from the line by an optical fiber 8.

Description

Detailed Description of the Invention

[0001]

The present invention relates to line signals (for example, phase current, zero-phase current, phase voltage, zero-phase voltage) in a distribution line,
The present invention relates to a line signal detection device used when transmitting to a place away from a line.

[0002]

2. Description of the Related Art As a device of this type, a CT or other detector attached to a distribution line and an electric wire for transmitting a line signal output from the detector in the form of an analog electric signal to a remote place. It is known to consist of
Such a device has an advantage that it can be implemented at a low cost because an existing detector can be used.

[0003]

However, in the above device,
Since the location of the detector and the location of receiving the line signal are electrically connected via the electric wire, noise such as electromagnetic induction, electrostatic induction, and surge is easily received, and the line signal passes through the electric wire. Noise easily enters during transmission,
There is a problem that the detection accuracy is likely to be lowered due to the influence of the noises.

Therefore, as an attempt to eliminate the above problems, an apparatus for transmitting a line signal using an optical fiber has been considered. However, such a device has a problem that a special detector is required. For example, as shown in FIG. 6, the apparatus is provided for each of A phase 101, B phase 102, and C phase 103 of the distribution line.
Detector 10 equipped with a photovoltage sensor and a photocurrent sensor that detect line voltage and line current and output them as optical signals, respectively.
Install 4, 105, 106. The optical signals output from these detectors are sent to the optical fibers 107 to 112.
Therefore, for example, the light signal is introduced to the lower part of the utility pole, the optical signal thereof is converted into an electric signal in the reception side signal processing unit 113, and each phase voltage, each phase current, zero phase voltage, zero phase current is detected.

FIG. 7 shows a part of the above device in more detail.
As described above, the light from the light source 114 of the reception side signal processing unit 113 is given to the detector 104 by another optical fiber 117, and in the detector 104, the light is supplied to the photocurrent sensor 115 (of the photovoltage sensor of the Faraday element). In this case, it is modulated by a modulation element such as a Pockel element, extracted through the analyzer 116 as the intensity of light, that is, as an analog amount, and is supplied to the reception side signal processing unit 113 by the optical fiber 107. Incidentally, 119 is a polarizer, 120 is an optical transmitter, 121 is a photodetector, and 122.
Is an optical receiver, 123 is an AC amplifier, 124 is a DC amplifier, and 125 is a divider.

However, in such a device, the above-mentioned photocurrent sensor and photovoltage sensor hermetically seal the modulator element 115 in the insulator 118 and hermetically seal the optical fibers 107 and 117 for the purpose of avoiding the influence of the external environment. Since it is structured to be led out of the insulator 118, the manufacturing cost is increased and the cost is increased.
Also, in the above device, since the signal is treated as an analog quantity,
The problem that the modulation element (Faraday element, Pockel element) is easily affected by the temperature characteristics, and that even if the brightness of the light source 114 slightly changes, it affects the detection signal value, which causes a decrease in detection accuracy. There is also.

The present invention has been made in order to solve the above-mentioned problems (technical problems) of the prior art, and it goes without saying that the line signal can be transmitted to a place distant from the line, and an existing detector is inexpensive as a detector. A signal detecting device in a distribution line in which the above-mentioned line signal can be transmitted with high accuracy, and the power supply of the signal processing unit required for the transmission can be obtained by a simple means. Is intended to provide.

[0008]

In order to achieve the above object, a signal detecting device for a distribution line according to the present invention separates an output signal of a detecting part from a detecting part for detecting a line signal of the distribution line. A signal detecting device in a power distribution line comprising a transmission line for transmitting to a location, wherein the detection unit is a detector attached to the power distribution line and outputting a line signal detected from the line in the form of an analog electric signal. And a signal processing section for converting the output signal of the detector into a digital optical signal and outputting the signal, and a power supply section for supplying a current for operating the signal processing section, wherein the transmission line is the digital signal. The optical power source for transmitting the optical signal of 1., the power supply unit, the porcelain capacitor for stepping down the high voltage of the distribution line, and the voltage stepped down by the porcelain capacitor No. processor and power transformer for the low voltage for operating, which is constituted by a rectifier for rectifying the secondary output of the power transformer.

[0009]

[Operation] The high voltage of the power distribution line is stepped down by the porcelain capacitor, further stepped down by the power transformer to become the low voltage for operating the signal processing part, and further rectified by the rectifier to become direct current, which is supplied to the signal processing part. Then, the processing unit operates. The line signal of the distribution line is detected by the detector and output in the form of an analog electric signal. The line signal is converted into a digital optical signal in the signal processor. The line signal is sent through an optical fiber.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a detector for detecting a line signal of a distribution line 1, for example, a line current of an imaginary high-voltage distribution line. It may be one that detects a line current of a distribution line buried underground. Reference numeral A denotes a detector that detects the line current of the distribution line 1. Reference numeral 2 denotes a detector in the detection unit, which outputs a line signal detected from the distribution line, for example, a line current in the form of an analog electric signal, for example, a current transformer (CT) is used. Reference numeral 3 is a signal processor in the detection device, which is attached to, for example, a wire arm of a utility pole. There are also cases where the pole part of the utility pole is installed in a place where people cannot reach it. Reference numeral 3a is a signal processing unit in the processor 3, which is for outputting an analog electric signal detected by the detector 2 and output from the output end thereof as a digital optical signal. A / D converter 4 for converting to a digital signal, P / S converter 5 for converting the digitized signal from parallel to serial signal, and A / D converter 4 Control circuit 6 for time-controlling an input signal to the P / S converter 5 and an output signal from the P / S converter 5, and a light emitting element for converting a digital electric signal from the P / S converter 5 into a digital optical signal And an E / O converter 7 consisting of. The light emitting element of the E / O converter 7 includes a light emitting diode (L
ED), a semiconductor laser (LD), etc. are used.

Next, 8 is a transmission line for transmitting the output signal of the detection section A, which is constituted by an optical fiber.
Next, 9 is a receiver for receiving a line signal in the form of an optical signal transmitted by the optical fiber 8, which is an O / E converter including a light receiving element for converting the digital optical signal into a digital electric signal. It is configured with. A photodiode (PD), an avalanche photodiode (APD), or the like is used as the light receiving element. 10 is an O / E converter 9
It is a display terminal configured to receive and output an electric (output) signal from a current waveform output display, and a personal computer is used as an example.

Next, 3b is a power supply unit in the signal processor 3,
It is for supplying the signal processing unit 3a with a direct current having a voltage suitable for operating it. Reference numeral 11 is a power supply circuit in the power supply unit, and 14 is a constant voltage circuit for making the output of the power supply circuit 11 constant.

Next, FIG. 2 showing an example of the power supply circuit 11 will be described. 12a to 12c are porcelain capacitors for stepping down the high voltage of the distribution line, which are multi-phase, for example, three-phase distribution lines.
Each of the lines 1a to 1c (reference numeral 1 in FIG. 1 indicates a distribution line of one phase among these distribution lines) is attached to each line so as to step down the high voltage. Reference numerals 13a to 13c denote the voltage stepped down by the porcelain capacitor and the signal processing unit 3b.
A power supply transformer for setting a low voltage for operating the power supply, which is provided for each phase as shown in the figure. Reference numerals 13a 'to 13c' denote the primary side of the power transformer, and 13a "to 13c" denote the secondary side. Reference numeral 15 is a capacitor exemplified as a detector for detecting the zero-phase voltage in the line signal, and the zero-phase voltage obtained across the capacitor 15 may be input to the signal processing unit 3a. Reference numeral 16 is a rectifier for rectifying the secondary side output of the power transformer, which is a bridge type for rectifying the above three phases.
The porcelain capacitor 12a has, for example, the structure shown in FIG. 3, and 21 is a porcelain bushing through which the power distribution line 1a passes. Reference numeral 22 denotes an electrode provided around a part of the bushing 21, and the electrode 22 and the outer peripheral surface of the distribution line 1a form a capacitor, and the electrode 22 is connected to the primary side of the power transformer. The other porcelain capacitors 12b and 12c have the same configuration.

In the structure described above, the power supply circuit 11 produces low-voltage DC current from high-voltage AC current.
That is, the high voltage of the distribution lines 1a to 1c of each phase is the porcelain capacitor.
The voltage is stepped down by 12a to 12c and further lowered to a lower voltage by the power transformers 13a to 13c, and the secondary side output is rectified by the rectifier 16 to become direct current. The direct current is supplied to the signal processing unit 3a via the constant voltage circuit 14, and the signal processing unit 3a operates.
The current flowing in the line 1 is detected by the current transformer 2, and the line signal in the form of an analog electric signal output from the current transformer 2 is converted into a digital optical signal by the signal processing unit 3a and received through the optical fiber 8. It is transmitted to the part 9. Then, there, it is converted into a digital electric signal, and the detected current is displayed in the terminal 10. In the above configuration, since the power supply transformers 13a to 13c are arranged in three phases, the power supply for driving the signal processing unit can be secured even when a ground fault occurs.

Next, FIG. 4 shows a different embodiment of the power supply circuit 11d. The current transformers 24 and 25 for power supply are respectively attached to the plural phases 1ad and 1cd of the power distribution line, and the respective current transformers 24 and 25. The rectifier rectifies the output of 25, for example, bridge rectifiers 26 and 27. Reference numerals 2a to 2c are line signal detectors, and show current transformers for detecting a phase current of each phase. The current transformer for power supply and the current transformer for signal detection may be combined. In the example of FIG. 4 described above, parts that are considered to have the same or equivalent configurations as those in the previous figure in terms of function are denoted by the same reference numerals as in the previous figure and the duplicated description is omitted by adding the letter d. (Also, in the following figure, the letter e is attached to the same idea and the duplicated explanation is omitted.)

Next, FIG. 5 shows an embodiment of a detecting device in the case where the line signal to be detected is a voltage. For example, a zero-phase voltage detecting device for judging the directionality at the time of detecting a ground fault accident is shown. Has been done. In the figure, 18 is a high-voltage distribution line for each phase 1ae-1
It is a ZPD (zero phase voltage detector) connected to ce. The ZP
The output terminal of D is connected to the input terminal of the signal processor 3e, that is, the A / D converter 4e.

As an application example of the above-described detection device,
It can be used for line condition monitoring, accident detection such as ground fault short-circuit detection, power distribution equipment deterioration detection, voltage / current waveform observation with the spread of thyristor equipment, and optical power meter.

[0018]

As described above, according to the present invention, when it is desired to know the line signal of the distribution line 1, the detection unit A detects the line signal from the line 1 and transmits it by the transmission line 8.
Of course, there is a feature that the line signal can be known at a place distant from the line 1, and in the detection unit A,
Since the detector 2 that outputs a line signal in the form of an analog electric signal is used, an existing detector can be used as the detector 2, which is economically effective. .

Moreover, even if the detector 2 as described above is used, the analog electric signal is converted into a digital optical signal in the signal processing section 3a and transmitted through the optical fiber 8. The place where the signal is received is electrically insulated from the detection unit A, is not easily affected by noise such as electromagnetic induction, electrostatic induction, surge, etc., and is less likely to be mixed with noise during transmission. Since the signal is digital, it is less likely to be affected by fluctuations in the intensity of the light, and therefore the line signal can be transmitted to the remote place with high accuracy.

Further, since the power supply section 3b for operating the signal processing section 3a is adapted to take the current from the distribution line 1, the current is continuously supplied as long as the distribution line 1 is in the charged state. There is a feature that can be. This has the advantage that maintenance of the signal detection device can be facilitated by eliminating the need for consideration for consumption as in the case of incorporating a storage battery or a dry battery.

Further, in the power source section 3b, the distribution line 1
Is first stepped down by the porcelain capacitor 12a, and further stepped down by the power transformer 13a to obtain a low voltage for operating the signal processing unit 3a. Therefore, even if the porcelain capacitor 12a has a low capacity, Secondary side 13a
There is an effect that a sufficiently large current can be obtained in the case of a ", and the rectifier 16 can rectify it to obtain a direct current for operating the signal processing unit.

Further, the power supply unit is a plurality of phases 1a of the distribution line.
When the current transformers 24 and 25 respectively attached to d and 1cd are provided, even if an accident occurs in one of the phases of the above-mentioned distribution line and the current of that phase is interrupted, the current of the other phase is transformed. There is an effect that the electric current for operating the signal processing unit can be secured by the device and the operation of the signal detecting device can be continued.

[Brief description of drawings]

FIG. 1 is a schematic block diagram for explaining a current detection device.

FIG. 2 is a circuit diagram of a power supply circuit.

FIG. 3 is a vertical sectional view of a porcelain capacitor.

FIG. 4 is a circuit diagram showing another embodiment of the power supply circuit.

FIG. 5 is a schematic block diagram for explaining a zero-phase voltage detection device.

FIG. 6 is a schematic diagram for explaining a conventional voltage / current detection device.

7 is a diagram for explaining a main part of the apparatus of FIG.

[Explanation of symbols]

 1 distribution line 2 detector 3a signal processing unit 3b power supply unit 8 optical fiber for optical signal transmission

Claims (2)

[Claims] 1. A signal detecting device in a power distribution line, comprising: a detection unit for detecting a line signal of the power distribution line; and a transmission line for transmitting an output signal of the detection unit to a distant place. A detector that is attached to the distribution line and outputs a line signal detected from the line in the form of an analog electric signal; a signal processing unit that outputs the detector output signal as a digital optical signal; The processing section is composed of a power supply section for supplying a current for operating the processing section, the transmission line is composed of an optical fiber for transmitting the digital optical signal, and the power supply section is of the power distribution line. A porcelain capacitor for stepping down a high voltage, a power transformer for reducing the voltage stepped down by the porcelain capacitor to a low voltage for operating the signal processing section, and a secondary output of the power transformer. A signal detection device in a power distribution line, comprising a rectifier for rectifying a force. 2. A signal detecting device in a power distribution line, comprising: a detection unit for detecting a line signal of the power distribution line; and a transmission line for transmitting an output signal of the detection unit to a remote place. A detector that is attached to the distribution line and outputs a line signal detected from the line in the form of an analog electric signal; a signal processing unit that outputs the detector output signal as a digital optical signal; The processing section is composed of a power supply section for supplying a current for operating the processing section, the transmission line is composed of an optical fiber for transmitting the digital optical signal, and the power supply section is of the power distribution line. A signal detecting device in a distribution line, comprising a current transformer attached to each of a plurality of phases, and a rectifier rectifying the output of each current transformer.