JP2008154411A - Protection relay system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple and compact protection relay system capable of improving noise resistance. <P>SOLUTION: This protection relay system 110 includes an optical sensor 111 for detecting current passing through an electric circuit L and a relaying device 112 for interrupting the electric circuit with the electric circuit L using a detection result output from the optical sensor 111. The optical sensor 111 is connected with the relaying device 112 through an optical line 113. The relaying device 112 includes a signal processing section 124 for performing predetermined signal processing by photoelectrically converting a detected optical signal as the detection result which is output from the optical sensor 111 and input through the optical line 113. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention detects a current or voltage of an electrical facility such as a generator, a transformer, or a power line, determines whether there is an abnormality in the facility, and based on the determination result, protects the electrical circuit that is in an abnormal state. It relates to the electric system.

  Detects any abnormal state that has occurred in the generators, transformers, power lines, etc. that make up the power system, isolates the abnormal part from the healthy part at high speed, prevents the abnormal state from spreading, Preventing continuation and protecting equipment is very important for stable power supply and equipment protection. Such a role for smoothly operating the power system is played by the detection device and the relay device.

  Specifically, when the detection device captures the electrical phenomenon of the facility and determines whether the relay device is normal or abnormal based on the electrical signal transmitted by the detection device, The system is protected by giving an open command to the circuit breaker. Examples of the case of determining an abnormality include, for example, a case where an electrical signal caused by equipment failure or destruction such as overcurrent, overvoltage, or voltage drop is detected.

  Thus, the relay device plays a very important role to ensure the reliability of power supply. The entire detection device and relay device are collectively referred to as a protective relay system (protection relay system).

  As the performance required for the relay device, for example, in the case of a relay device for removing an accident, a reliable operation is required when a system fault occurs. That is, it is required to achieve both high-speed operation and discrimination performance, and both operation reliability and non-operation reliability.

  10 and 11 are examples of block diagrams of a conventional protective relay system used for detecting the current and voltage of the electric circuit. The conventional protective relay systems 410 and 510 include an instrument current transformer 411 or an instrument transformer 511 and relay devices 412 and 512 arranged in the facility (electrical line L in this example). These are connected by connection lines 413 and 513 such as coaxial cables.

  For example, in the case of FIG. 10, the instrument current transformer 411 detects the current flowing through the electric circuit L. Specifically, the current generated due to the change in magnetic flux due to the change in current is output to the secondary side of the current transformer for instrument. Normally, this secondary current is adjusted to be 1 A or 5 A when the electrical equipment is at the rated current.

  For example, in the case of FIG. 11, the instrument transformer 511 detects the voltage applied to the electric circuit L. Normally, the output voltage on the secondary side of the instrument transformer is adjusted so that the output is 110 volts when the voltage applied to the electric circuit L is the rated voltage.

  The connection lines 413 and 513 are relays for the current or voltage (detection signal) that appears on the secondary side of the instrument current transformer 411 or the instrument transformer 511 (hereinafter collectively referred to as “instrument transformer”). 412 and 512. The relay devices 412 and 512 include transformers 401 and 501, A / D converters 425 and 525, and CPUs (central processing units) 426 and 526. The transformers 401 and 501 are connected to the connection lines 413 and 513 on the primary side, and convert the electrical signal (current or voltage) input through the connection lines 413 and 513 into a lower electrical signal to convert to the secondary side. Output from. The A / D converters 425 and 525 perform sampling and quantization on the electric signals converted from the transformers 401 and 501 and output from the secondary side of the transformers 401 and 501, and convert them into digital signals. . The CPUs 426 and 526 obtain the current or voltage of the electric circuit L using the digital signal output from the A / D converters 425 and 525, determine whether there is an abnormality in the equipment such as overcurrent or overvoltage, and determine that it is abnormal. In such a case, control for operating the circuit breaker associated with the electric circuit L is performed in order to prevent the spread and continuation of abnormal conditions such as overcurrent.

  Instrument current transformers include winding, through, and bushing types. In addition, the instrument transformer includes a winding type and a capacitor type.

  In recent years, research and development of photocurrent sensors using the Faraday effect and photovoltage sensors using the Pockels effect have been promoted as sensors that replace the above-described measuring transformers 411 and 511 such as windings. .

In the following Patent Document 1, an optical fiber is disposed in the vicinity of a display indicating an operation state of an overcurrent relay, and a color sensor for determining the color of light propagated through the optical fiber is provided. An apparatus is disclosed that allows accident information to be known at a distant place. The following Patent Document 2 discloses an apparatus for measuring an electric current of an electric circuit using a transmissive optical fiber sensor. Patent Document 3 below discloses an apparatus for measuring an electric current of an electric circuit using a reflection type optical fiber sensor and a transmission type optical fiber sensor. Further, Patent Document 4 below discloses an apparatus for measuring an electric circuit voltage using an optical sensor.
JP-A-6-295653 JP 2000-171659 A WO2003 / 075018 republished patent Japanese Patent Laid-Open No. 7-83961

  By the way, in the above-described conventional protective relay system, signals detected by the instrument transformers 411 and 511 to detect the current and voltage of the equipment are connected to the relay device 412 by connecting wires 413 and 513 made of a conductive material. 512. Since the connection lines 413 and 513 are made of a conductive material, the connection lines 413 and 513 are easily affected by electrical signals other than the equipment being monitored, such as a lightning surge current, a switching surge current, and an abnormal state of another nearby equipment. And the noise signal which this electric signal brings has had the problem that a relay device malfunctions or a relay device breaks down.

  In addition, when the instrument transformers 411 and 511 themselves are conductive, an electrical signal from the outside also affects the instrument transformer, and the relay device malfunctions or the relay device fails. There was a problem.

  Further, assuming that a large noise signal is input to the protective relay, in order to protect the device, a non-linear resistance element (varistor) 427 (427a, 427b), 527 ( 527a and 527b), the circuit is complicated and the number of parts is increased.

  In addition, there is a problem even when the instrument transformers 411 and 511 are not made of a conductive material and are optical sensors such as the above-described photocurrent sensor and photovoltage sensor. These optical sensors include sensor elements, optical system components such as optical fibers, light sources, electronic circuits constituting a signal processing unit, and the like. In order to use this optical sensor as an alternative to the above-described winding transformers 411 and 511, an output signal (electric signal) from the optical sensor is connected to the relaying devices 412 and 512 through the conductive connection lines 413 and 513, respectively. Need to be transmitted.

  Furthermore, with this configuration, there is a problem that a space for installing the housing of the optical sensor is required in addition to the relay devices 412 and 512, and that the configuration is complicated and the usability of the relay device is deteriorated. Moreover, although there exists an advantage of eliminating the influence of a surge etc. to a sensor part by using an optical sensor, there exists a possibility that noise may infiltrate from the connection lines 413 and 513. Therefore, the problem that the connection lines 413 and 513 are conductive cannot be solved, and there is a problem that the relay device malfunctions due to noise.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a protective relay system that is simple and small in size and can improve noise resistance.

In order to solve the above-mentioned problem, the protection relay system of the present invention outputs a detection device that detects an electrical phenomenon of a measurement target (for example, an electric circuit L that is one of the facilities) and the detection device. In a protective relay system (110, 210, 310) comprising a relay device (112, 212, 312) for performing control for blocking electrical connection to the facility using a detection result,
The detection device comprises an optical sensor,
The detection device and the relay device are connected by an optical line (113, 213, 313),
The relay device is a signal processing unit (124, 224, 324) that performs predetermined signal processing by photoelectrically converting the detection light signal output from the optical sensor and input through the optical line as the detection result. ).

  According to the present invention, the detection optical signal output from the optical sensor is transmitted to the relay device through the optical line, and is subjected to photoelectric conversion by the signal processing unit provided in the relay device to perform predetermined signal processing.

  In the protective relay system according to the present invention, the optical sensor is a sensor that detects a current flowing through the measurement target by detecting a magnetic field generated by the current flowing through the measurement target.

  In the protective relay system of the present invention, the optical sensor is a sensor that detects the voltage of the measurement object by detecting an electric field generated by the voltage applied to the measurement object. .

  In the protective relay system of the present invention, the relay device includes light sources (121, 221 and 321) for emitting an optical signal used for detecting the current by the optical sensor, and the optical line includes: Along with the propagation of the detection optical signal, the optical signal emitted from the light source is propagated to the optical sensor.

  In the protection relay system of the present invention, the optical sensor includes a branching optical system (111c, 211c, 311c) for branching the detection optical signal at a branching ratio corresponding to the optical characteristic thereof, and the optical line Is characterized in that each of the detection optical signals branched by the branching optical system is propagated individually or individually.

  Furthermore, in the protective relay system of the present invention, the signal processing unit converts the detection optical signals input via the optical path into electrical signals, the first and second photoelectric conversion elements (131, 132, 231, 232) and a DC component and an AC component extracted from the electric signals converted by the first and second photoelectric conversion elements, respectively, and a modulation degree signal obtained by normalizing the AC component with the DC component is obtained. A normalization processing unit (133) to be obtained and an averaging processing unit (134) for performing an averaging process by obtaining a difference between the modulation degree signals obtained by the normalization processing unit are provided. .

  In the protection relay system of the present invention, the signal processing unit converts the detection optical signal input via the optical line into an electric signal, the first photoelectric conversion element (331), and the first And a normalization processing unit (333) for respectively extracting a DC component and an AC component from the electrical signal converted by the photoelectric conversion element and obtaining a modulation degree signal obtained by normalizing the AC component with the DC component. It is a feature.

  Furthermore, in the protection relay system of the present invention, the signal processing unit includes an output adjustment circuit (338) that adjusts an input / output conversion ratio with respect to the signal of the normalization processing unit (333). It is said.

  According to the present invention, the detection optical signal output from the optical sensor is transmitted to the relay device via the optical line, and is subjected to predetermined signal processing by photoelectric conversion by the signal processing unit provided in the relay device. A protective relay system can be configured from an optical sensor, an optical line, and a relay device having a simple configuration. Therefore, there is an effect that the protective relay system can be made simple and small. Moreover, since the detection result (detection light signal) of the optical sensor is transmitted to the signal processing unit of the relay device via the optical line, there is an effect that noise resistance can be improved.

  Hereinafter, a protection relay system according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a protective relay system according to an embodiment of the present invention. As shown in FIG. 1, the protective relay system 110 of this embodiment includes an optical sensor 111 and a relay device 112 arranged around the electric circuit L, and these are connected by an optical line 113.

  The optical sensor 111 is a sensor that detects a current flowing through the electric circuit L. Specifically, the current flowing through the electric circuit L is detected by detecting the magnetic field generated by the current flowing through the electric circuit L. Here, when the current flowing through the electric circuit L is detected by detecting the magnetic field with the optical sensor 111, the optical sensor 111 including the Faraday sensor element is used.

  FIG. 2 is a diagram for explaining the principle of the Faraday sensor element. A cylindrical bar-shaped transparent member denoted by reference numeral 11a in FIG. 2 is a Faraday sensor element, and is formed by using, for example, lead glass having a very small photoelastic constant. It is assumed that a current i flows in a direction intersecting the axial direction (longitudinal direction) of the Faraday sensor element 11a, and a magnetic field H is generated in a direction along the axial direction of the Faraday sensor element 11a by the current i.

When light Li from one end of the Faraday sensor element 11a of this state is incident, the light Li is rotated plane of polarization by the Faraday effect while propagating through the Faraday sensor element 11a, the polarization plane is rotated by the Faraday rotation angle theta _F Injected from the other end. Since the Faraday rotation angle θ _F is proportional to the magnitude of the magnetic field H, by measuring the Faraday rotation angle θ _F , the magnitude of the current flowing through the electric circuit L that is the source of the magnetic field H can be detected.

Here, in order to detect the current i, the Faraday rotation angle θ _F of the light Li emitted from the other end of the Faraday sensor element 11a may be measured. This type of photocurrent sensor is referred to as a transmissive photocurrent sensor (see FIG. 6). Further, the light Li emitted from the other end of the Faraday sensor element 11a is reflected by the reflection type optical system 111b (see FIG. 3), and the Faraday rotation angle θ of the light Li after passing through the Faraday sensor element 11a again. _F (actually, 2θ _F ) because light reciprocates and reciprocates may be measured. This type of photocurrent sensor is referred to as a reflective photocurrent sensor. It is preferable to use a reflective photocurrent sensor because the photosensor can be downsized and flexible.

The optical sensors 111 (see FIG. 3) and 211 (see FIG. 6) are not limited to the above-mentioned Faraday sensor element 11a (if a reflective photocurrent sensor is used, the Faraday sensor element 111a and the reflective optical system 111b). The branch optical systems 111c (see FIG. 3) and 211c (see FIG. 3) branch the light Li via the Faraday sensor element 11a at a ratio corresponding to the Faraday rotation angle θ _F (2θ _F when using a reflective photocurrent sensor). 6).

  As shown in FIG. 1, the relay device 112 includes a light source 121, a variable attenuator 122, a circulator 123, a signal processing unit 124, an A / D converter 125, and a CPU (central processing unit) 126, and an optical sensor The electric circuit (not shown) related to the electric circuit L is interrupted as necessary using the detection result 111. More specifically, control for operating a circuit breaker or a switch is performed or a signal for that purpose is transmitted in order to cut off the electrical connection. The light source 121 emits an optical signal used for detecting the current flowing through the electric path L by the optical sensor 111. For example, a semiconductor laser light source that emits laser light such as a 0.6 μm band, a 0.8 μm band, and a 1.5 μm band. Is used. The variable attenuator 122 adjusts the optical signal emitted from the light source 121 and sets it to a predetermined light intensity.

  The circulator 123 emits an optical signal emitted from the light source 121 and enters the optical line 113 (113a) via the variable attenuator 122, and is output from the optical sensor 111 and detected optical signal via the optical line 113 (113a). To the signal processing unit 124. As shown in FIG. 1, the optical line 113 that connects the optical sensor 111 and the relay device 112 includes two optical lines 113a and 113b.

  Here, the configuration of the optical system of the protective relay system 110 will be described more specifically. FIG. 3 is a diagram illustrating a specific configuration of the optical system of the protective relay system 110. As shown in FIG. 3, the light source 121 is connected to the optical connector C11 directly or via a variable attenuator 122 (not shown in FIG. 3). Further, one photodiode (PD: photoelectric conversion element) 131 provided in the signal processing unit 124 is connected to the optical connector C12, and the other photodiode 132 is connected to the optical connector C13. The optical connector C11 and the circulator 123 are connected by an optical line (optical fiber) F11. The optical connector C12 and the circulator 123 are connected by an optical fiber S11.

  The circulator 123 is connected to the optical connector C14 to which the optical line 113a is connected by an optical fiber F12. The optical connector C13 is connected to the optical connector C15 to which the optical line 113b is connected by an optical fiber S13. These optical lines 113a and 113b are connected to a branching optical system 111c provided in the optical sensor 111. The branching optical system 111c also performs an operation that serves as both a polarizer and an analyzer. The branching optical system 111c includes a rotating Faraday element, a magnet that applies a magnetic field to the rotating Faraday element, a lens, a birefringent body, and the like (not shown). The birefringent body is set so that the polarization plane orientation of the light emitted from the light source 121 is inclined at a certain angle (approximately 22.5 °) with respect to the vertical coordinate axis of the coordinate system where the optical sensor is placed. The

  In the above configuration, the light emitted from the light source 121 enters the circulator 123 via the variable attenuator 122 (not shown), the optical connector C11, and the optical fiber F11 (not shown) in this order, and then the optical fiber F12 and The light propagates through the optical line 113a via the optical connector C14 and enters the optical sensor 111. The light incident on the optical sensor 111 passes through the Faraday sensor element 111a via the branch optical system 111c, is reflected by the reflective optical system 111b, and passes through the Faraday sensor element 111a in the reverse direction to enter the branch optical system 111c. Re-enter. The light re-entering the branching optical system 111c is separated into two orthogonal components and enters the optical lines 113a and 113b.

Here, if no current flows through the electric path L, the plane of polarization does not rotate even if light passes through the Faraday sensor element 111a. For this reason, the light re-entering the branching optical system 111c is branched such that the light amounts of the two components are equal. On the other hand, when a current flows through the electric path L, the polarization plane is rotated by the magnetic field generated due to the current flowing through the electric path L when light passes through the Faraday sensor element 111a. polarization plane of the light re-entering the 111c are rotated by the Faraday rotation angle 2 [Theta] _F. Therefore, the light reenters the splitting optical system 111c is branched at a ratio corresponding to the Faraday rotation angle 2 [Theta] _F. Note that the branched light branched by the branching optical system 111c is a detection light signal.

  One of the detection optical signals branched by the branching optical system 111c is incident on the optical line 113a, and the other is incident on the optical line 113b and propagates individually. The detected optical signal via the optical line 113a enters the circulator 123 via the optical connector C14 and the optical fiber F12 in order, and then the photodiode provided in the signal processing unit 124 via the optical fiber S11 and the optical connector C12 in order. The light is received at 131. In addition, the detection optical signal via the optical line 113b is received by the photodiode 132 provided in the signal processing unit 124 via the optical connector C15, the optical fiber S12, and the optical connector C13 in this order.

  The signal processing unit 124 performs predetermined signal processing by photoelectrically converting the detection light signal output from the optical sensor 111 and input via the optical line 113. FIG. 4 is a block diagram illustrating a configuration of the signal processing unit 124. As shown in FIG. 4, the signal processing unit 124 includes two photodiodes 131 and 132, a normalization processing unit 133, and an averaging processing unit 134. As described above, the photodiode 131 receives the detection light signal via the optical line 113a, and the photodiode 132 receives the detection light signal via the optical line 113b.

  The normalization processing unit 133 includes band pass filters (BPF) 135a and 135b, low pass filters (LPF) 136a and 136b, and dividers 137a and 137b. The band pass filter 135a extracts an AC component from the electrical signal output from the photodiode 131. The low pass filter 136a extracts a DC component from the electrical signal output from the photodiode 131.

  Similarly, the band pass filter 135b extracts an alternating current component from the electric signal output from the photodiode 132, and the low pass filter 136b extracts a direct current component from the electric signal output from the photodiode 132. The divider 137a divides the AC component extracted by the bandpass filter 135a by the DC component extracted by the low-pass filter 136a, thereby obtaining a modulation degree signal obtained by normalizing the AC component with the DC component. Similarly, the divider 137b divides the alternating current component extracted by the band pass filter 135b by the direct current component extracted by the low pass filter 136b, thereby obtaining a modulation degree signal obtained by normalizing the alternating current component with the direct current component.

  The averaging processing unit 134 includes a polarity inverter 138 and an adder 139, and performs an averaging process by obtaining a difference between the modulation degree signals obtained by the normalization processing unit 133. The polarity inverter 138 inverts the polarity of the modulation degree signal obtained by the divider 137b of the normalization processing unit 133. The adder 139 adds the modulation factor signal obtained by the divider 137 a of the normalization processing unit 133 and the modulation factor signal output from the divider 137 b and inverted in polarity by the polarity inverter 138. The averaging process is performed by the above process, and the influence of the optical bias fluctuation can be reduced by performing the averaging process.

  The A / D converter 125 samples and quantizes the signal output from the signal processing unit 124 and converts the signal into a digital signal. The CPU 126 obtains the current flowing through the electric circuit L using the digital signal output from the A / D converter 125, determines the presence or absence of an abnormality such as an overcurrent, and prevents the overcurrent or the like when it is determined that there is an abnormality. Therefore, control etc. which cut off the electric circuit concerning electric circuit L are performed.

  When the detection light signal that has passed through the optical system of the protective relay system 110 shown in FIG. 1 enters the signal processing unit 124, it is received by the photodiodes 131 and 132, respectively. The electric signal output from the photodiode 131 is input to the band pass filter 135a and the low pass filter 136a, and an AC component and a DC component are extracted, respectively. Similarly, the electrical signal output from the photodiode 132 is input to the band pass filter 135b and the low pass filter 136b, and an AC component and a DC component are extracted, respectively.

  The alternating current component and the direct current component extracted by the band pass filter 135a and the low pass filter 136a are input to the divider 137a, and the alternating current component is normalized by the direct current component to obtain a modulation degree signal. Similarly, the alternating current component and the direct current component extracted by the band pass filter 135b and the low pass filter 136b are input to the divider 137b, and the alternating current component is normalized by the direct current component to obtain a modulation degree signal. The modulation degree signal obtained by the divider 137b is inverted in polarity by the polarity inverter 138 and then added to the modulation degree signal obtained by the divider 137a by the adder 139. Thereby, an averaging process is performed.

  The modulation degree signal subjected to the averaging process is converted into a digital signal by the A / D converter 125 and input to the CPU 126. The CPU 126 obtains the current flowing through the electric circuit L using the digital signal output from the A / D converter 125, determines the presence / absence of an abnormality such as an overcurrent, and determines that there is an abnormality, for example, an overcurrent or the like. In order to prevent this, the control etc. which interrupt the electric circuit which concerns on the electric circuit L are performed.

  As described above, according to the present embodiment, the signal processing unit 124 that performs predetermined signal processing by photoelectrically converting the detection optical signal output from the optical sensor 111 and input through the optical line 113 is relayed. 112. For this reason, the protective relay system 110 can be comprised from the optical sensor 111 of the simple structure, the optical line 113, and the relay apparatus 112, and the protective relay system 110 can be made simple and small. Moreover, according to this embodiment, since the detection result (detection light signal) of the optical sensor 111 is transmitted to the signal processing unit 124 of the relay device 112 via the optical line 113, noise resistance is improved. Can do. As a result, it is possible to improve the discrimination performance of the protective relay system and improve the reliability of operation and non-operation. This can be said to play an important role in the smooth operation of the power system. Furthermore, the non-linear resistance element provided for electrically protecting the elements and circuits in the relay device from overcurrent and overvoltage can be omitted or downsized.

  Next, a protection relay system according to another embodiment of the present invention will be described. FIG. 5 is a block diagram showing a schematic configuration of a protective relay system according to another embodiment of the present invention. As shown in FIG. 5, the protective relay system 210 of the present embodiment includes an optical sensor 211 and a relay device 212 that are arranged in the vicinity of the electric circuit L or arranged around the electric circuit L. They are connected by an optical line 213.

  Hereinafter, a protective relay system according to another embodiment of the present invention will be described in detail with reference to the drawings.

  The optical sensor 211 is a sensor that detects a current flowing through the electric circuit L, and uses a Faraday sensor element.

  The relay device 212 includes a light source 221, a variable attenuator 222 (can be omitted), a signal processing unit 224, an A / D converter 225, and a CPU (central processing unit) 226, and the detection result of the optical sensor 211 is displayed. The electric circuit (illustration abbreviation) concerning electric circuit L is intercepted using.

  As shown in FIG. 5, the optical line 213 that connects the optical sensor 211 and the relay device 212 includes three optical fibers 213a, 213b, and 213c.

  Here, the configuration of the optical system of the protective relay system 210 will be described more specifically. FIG. 6 is a diagram illustrating a specific configuration of the optical system of the protective relay system 210. As shown in FIG. 6, the light source 221 is connected to the optical connector C21 directly or via a variable attenuator 222 (not shown in FIG. 6). In addition, a photodiode (PD: photoelectric conversion element) 231 provided in the signal processing unit 224 is connected to the optical connector C22, and the other photodiode 232 is connected to the optical connector C23.

  The optical connector C21 is connected to the optical connector C24 to which the optical fiber 213a is connected by the optical fiber F21. The optical connector C22 is connected to the optical connector C26 to which the optical fiber 213c is connected by the optical fiber S23. The optical connector C23 is connected to the optical connector C25 to which the optical fiber 213b is connected by the optical fiber S22. The optical fiber 213a is connected to an optical connector C27 provided in the optical sensor 211, and the optical fibers 213b and 213c are connected to a branching optical system 211c provided in the optical sensor 211.

  In the above configuration, the light emitted from the light source 221 propagates through the optical fiber 213a via the variable attenuator 222 (not shown), the optical connector C21, the optical fiber F21, and the optical connector C24. Incident on the optical sensor 211. The light incident on the optical sensor 211 passes through the Faraday sensor element 211a via the polarizer 211d and enters the branching optical system 211c. Here, unlike the branching optical system 111c in the above-described embodiment, the branching optical system 211c does not also function as a polarizer. The polarizer is set so that the polarization plane orientation of the light emitted from the light source 221 is inclined at a certain angle (approximately 45 °) with respect to the vertical coordinate axis of the coordinate system where the sensor is placed. The light incident on the branching optical system 211c is separated into two orthogonal components by a birefringent body (analyzer) inherent in the branching optical system 211c, and enters the optical fibers 213b and 213c.

Here, if no current flows through the electric path L, the plane of polarization does not rotate even if light passes through the Faraday sensor element 211a. For this reason, the light incident on the branching optical system 211c is branched so that the light amounts are equal. On the other hand, when a current flows through the electric path L, the polarization plane is rotated by the magnetic field generated due to the current flowing through the electric path L when light passes through the Faraday sensor element 211a. polarization plane of the light incident on the 211c are rotated by the Faraday rotation angle theta _F. Therefore, light incident on the splitting optical system 211c is branched at a ratio corresponding to a Faraday rotation angle theta _F. The branched light branched by the branching optical system 211c is a detection light signal.

  One of the detection optical signals branched by the branching optical system 211c enters the optical fiber 213b, and the other enters the optical fiber 213c and propagates individually. The detection optical signal via the optical fiber 213b is received by the photodiode 232 provided in the signal processing unit 224 via the optical connector C25, the optical fiber S22, and the optical connector C23 in this order. The detection optical signal via the optical fiber 213c is received by the photodiode 231 provided in the signal processing unit 224 via the optical connector C26, the optical fiber S23, and the optical connector C22 in this order.

  The signal processing unit 224 photoelectrically converts the detection optical signal output from the optical sensor 211 and input through the optical line 213, and performs predetermined signal processing. The circuit and processing are the same as in the case of the reflective optical fiber sensor (see FIG. 4).

  When the detection light signal via the optical system of the protective relay system 210 shown in FIG. 5 enters the signal processing unit 224, the light is received by the photodiodes 231 and 232, respectively. The electrical signal output from the photodiode 231 is input to the band pass filter 135a and the low pass filter 136a, and an AC component and a DC component are extracted, respectively. Similarly, the electrical signal output from the photodiode 232 is input to the band pass filter 135b and the low pass filter 136b, and an AC component and a DC component are extracted, respectively.

  The alternating current component and the direct current component extracted by the band pass filter 135a and the low pass filter 136a are input to the divider 137a, and the alternating current component is normalized by the direct current component to obtain a modulation degree signal. Similarly, the alternating current component and the direct current component extracted by the band pass filter 135b and the low pass filter 136b are input to the divider 137b, and the alternating current component is normalized by the direct current component to obtain a modulation degree signal. The modulation degree signal obtained by the divider 137b is inverted in polarity by the polarity inverter 138 and then added to the modulation degree signal obtained by the divider 137a by the adder 139. Thereby, an averaging process is performed.

  The modulation degree signal subjected to the averaging process is converted into a digital signal by the A / D converter 225 and input to the CPU 226. The CPU 226 obtains the current flowing through the electric circuit L using the digital signal output from the A / D converter 225, determines the presence / absence of an abnormality such as an overcurrent, and determines that there is an abnormality, for example, an overcurrent or the like In order to prevent this, the control etc. which interrupt the electric circuit which concerns on the electric circuit L are performed.

  As described above, according to this embodiment, the signal processing unit 224 that performs predetermined signal processing by photoelectrically converting the detection optical signal output from the optical sensor 211 and input through the optical line 213 is relayed. 212. For this reason, the protective relay system 210 can be comprised from the optical sensor 211 of the simple structure, the optical line 213, and the relay apparatus 212, and the protective relay system 210 can be made simple and small. Moreover, according to this embodiment, since the detection result (detection optical signal) of the optical sensor 211 is transmitted to the signal processing unit 224 of the relay device 212 via the optical line 213, noise resistance is improved. Can do. As a result, it is possible to improve the discrimination performance of the protection metering system and improve the reliability of operation and non-operation. This can be said to play an important role in smooth operation of the power system. Furthermore, the non-linear resistance element provided for electrically protecting the elements and circuits in the relay device from overcurrent and overvoltage can be omitted or downsized.

  Next, a protection relay system according to another embodiment of the present invention will be described. FIG. 7 is a block diagram showing a schematic configuration of a protective relay system according to another embodiment of the present invention. As shown in FIG. 7, the protective relay system 310 of this embodiment includes an optical sensor 311 and a relay device 312 that are arranged in the vicinity of the electric circuit L or arranged around the electric circuit L. They are connected by an optical line 313.

  Hereinafter, a protection relay system according to an embodiment of the present invention will be described in detail with reference to the drawings.

  The optical sensor 311 is a sensor that detects a voltage applied to the electric circuit L. Specifically, the voltage applied to the electric circuit L is detected by detecting the electric field generated by the voltage applied to the electric circuit L (actually, the voltage divided by the voltage divider). Here, in the case where the electric field applied to the electric path L is detected by detecting the electric field with the optical sensor 311, the optical sensor 311 provided with the Pockels sensor element can be used.

The Pockels sensor element converts the intensity of an applied electric field into light intensity, and measures voltage from this light intensity. Examples of such electro-optic crystals include Bi ₁₂ , GeO ₂₀ , Bi ₁₂ O _20. , Bi ₁₂ SiO ₂₀ or the like having optical activity is used.

  The relay device 312 includes a light source 321, a variable attenuator 322 (can be omitted), a signal processing unit 324, an A / D converter 325, and a CPU (central processing unit) 326, and the detection result of the optical sensor 311 is displayed. The electric circuit (illustration omitted) which concerns on the electric circuit L is used, and it interrupts | blocks as needed.

  As shown in FIG. 7, the optical line 313 that connects the optical sensor 311 and the relay device 312 includes two optical fibers 313a and 313c.

  Here, the configuration of the optical system of the protective relay system 310 will be described more specifically. FIG. 8 is a diagram illustrating a specific configuration of the optical system of the protective relay system 310. As shown in FIG. 8, the light source 321 is connected to the optical connector C31 directly or via a variable attenuator 322 (not shown in FIG. 8). In addition, a photodiode (PD: photoelectric conversion element) 331 provided in the signal processing unit 324 is connected to the optical connector C32.

  The optical connector C31 is connected to the optical connector C34 to which the optical fiber 313a is connected by the optical fiber F31. The optical connector C32 is connected to the optical connector C36 to which the optical fiber 313c is connected by the optical fiber S33. The optical fiber 313a is connected to an optical connector C37 provided in the optical sensor 311, and the optical fiber 313c is connected to an optical connector C38 provided in the optical sensor 311.

  In the above configuration, the light emitted from the light source 321 propagates through the optical fiber 313a via the variable attenuator 322 (not shown), the optical connector C31, the optical fiber F31, and the optical connector C34. The light enters the optical sensor 311. The light incident on the optical sensor 311 passes through the polarizer 311d, the quarter-wave plate 311e, and the Pockels sensor element 311a, and enters the branching optical system (analyzer) 311c. A voltage to be measured is applied to both ends of the Pockels sensor element 311a via lead wires 311f and 311g. In addition, when the electric circuit L is a high voltage, the intensity change of the light obtained by the output of the voltage divider 340 is measured, and an operation in consideration of the voltage division ratio and the like is performed, so that the actual measurement target (for example, the electric circuit L) is measured. The applied voltage is measured.

  Here, if no voltage is applied to the electric circuit L, the refractive index does not change even if light passes through the Pockels sensor element 311a. For this reason, all the light incident on the analyzer 311c is received by the photodiode 331 via the optical connector C38 and the optical fiber 313c (when there is no optical line loss). On the other hand, when a voltage is applied to the electric path L, the light refractive index changes due to the electric field generated due to the voltage of the electric path L when the light passes through the Pockels sensor element 311a. The light incident on the analyzer 311c is branched at a ratio corresponding to the change in the refractive index of the light. The branched light branched according to the electric field strength by the analyzer 311c is a detection light signal. The intensity of light changes according to the intensity of the electric field.

  The detection optical signal branched by the branch optical system 311c is incident on the optical fiber 313c and propagated. The detection optical signal via the optical fiber 313c is received by the photodiode 331 provided in the signal processing unit 324 via the optical connector C36, the optical fiber S33, and the optical connector C32 in this order.

  The signal processing unit 324 photoelectrically converts the detection optical signal output from the optical sensor 311 and input through the optical line 313, and performs predetermined signal processing. FIG. 9 is a block diagram illustrating a configuration of the signal processing unit 324. As shown in FIG. 9, the signal processing unit 324 includes one photodiode 331, a normalization processing unit 333, and an output adjustment circuit 338. Note that the output adjustment circuit 338 may be omitted. Further, an amplifier circuit may be provided between the photodiode 331 and the normalization processing unit 333. As described above, the photodiode 331 receives the detection light signal via the optical fiber 313c.

  The normalization processing unit 333 includes a band pass filter (BPF) 335, a low pass filter (LPF) 336, and a divider 337. The band pass filter 335 extracts an AC component from the electrical signal output from the photodiode 331. Here, the AC component of the electric signal output from the photodiode 331 is an electric field generated by the voltage (the output voltage of the voltage divider in the case of a high voltage) applied to the electric circuit L by the light emitted from the light source 321. Proportionally modulated component. The low pass filter 336 extracts a direct current component from the electrical signal output from the photodiode 331.

  The divider 337 divides the AC component extracted by the bandpass filter 335 by the DC component extracted by the low-pass filter 336, thereby obtaining a modulation degree signal obtained by normalizing the AC component with the DC component.

  The output adjustment circuit 338 adjusts the input / output conversion ratio of the modulation degree obtained by the normalization processing unit 333 and performs analog output. Note that the output adjustment circuit 338 may be omitted.

  The A / D converter 325 performs sampling and quantization on the signal output from the signal processing unit 324 and converts the signal into a digital signal. The CPU 326 obtains the voltage applied to the electric circuit L using the digital signal output from the A / D converter 325, determines the presence / absence of an abnormality such as an overvoltage, and prevents the overvoltage or the like when the abnormality is determined. Therefore, control etc. which cut off the electric circuit concerning electric circuit L are performed.

  When the detection light signal via the optical system of the protective relay system 310 shown in FIG. 7 enters the signal processing unit 324, the light is received by the photodiode 331. The electric signal output from the photodiode 331 is input to the band pass filter 335 and the low pass filter 336, and an AC component and a DC component are extracted, respectively.

  The alternating current component and the direct current component extracted by the band pass filter 335 and the low pass filter 336 are input to the divider 337, and the alternating current component is normalized by the direct current component to obtain a modulation degree signal. The modulation degree signal obtained by the divider 337 is subjected to analog output by adjusting the input / output conversion ratio by the output adjustment circuit 338.

  The modulation degree signal output from the signal processing unit 324 is converted into a digital signal by the A / D converter 325 and input to the CPU 326. The CPU 326 obtains the voltage applied to the electric circuit L using the digital signal output from the A / D converter 325, determines the presence / absence of an abnormality such as an overvoltage, and determines that there is an abnormality, for example, an overvoltage or the like. In order to prevent this, the control etc. which interrupt the electric circuit which concerns on the electric circuit L are performed.

  As described above, according to the present embodiment, the signal processing unit 324 that performs predetermined signal processing by photoelectrically converting the detection optical signal output from the optical sensor 311 and input through the optical line 313 is relayed. 312 is provided. For this reason, the protective relay system 310 can be comprised from the optical sensor 311 of the simple structure, the optical line 313, and the relay apparatus 312. FIG. Therefore, the protective relay system 310 can be made simple and small. Moreover, according to this embodiment, since the detection result (detection optical signal) of the optical sensor 311 is transmitted to the signal processing unit 324 of the relay device 312 via the optical line 313, noise resistance is improved. Can do. Furthermore, the non-linear resistance element provided for electrically protecting the elements and circuits in the relay device from overcurrent and overvoltage can be omitted or downsized.

  The protection relay system according to the embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and can be freely changed within the scope of the present invention. For example, in the above-described embodiment, the configuration in which the light source, the variable attenuator, the circulator, and the signal processing unit are individually provided in the relay device has been described as an example. However, these are provided in one housing. The structure may be different. In addition, any or all of the light source and the variable attenuator may be arranged outside the relay device. Furthermore, it is preferable that the casing of the relay device is electrically shielded because it is less susceptible to noise caused by an external electrical signal.

  Furthermore, among the optical fibers that are the optical lines, F11, F12, 113a, F21, 213a, and F31, 313a are preferably polarization-maintaining optical fibers because there is less fluctuation of the polarization plane in the optical line during transmission. . This is because if the polarization plane fluctuates, the final output light amount fluctuates, which causes a measurement error.

  Other optical fibers are preferably single mode optical fibers. This is because a transmission loss increases in the case of a multimode optical fiber. However, if the distance is not too long, there is no need to stick to it. An optical fiber that can achieve a desired purpose may be used. Moreover, it is only necessary to be able to capture the amount of light, so there is no need to maintain the plane of polarization. Therefore, it is not necessary to use a polarization-maintaining fiber that is disadvantageous in terms of cost, but it may be used.

  Moreover, in the said embodiment, it consists of a Faraday sensor element or a Pockels sensor element which detects the electric current which flows through the electric circuit L, and the magnetic field and electric field which arise with the applied voltage, and detects the electric current which flows through the electric circuit L, and the applied voltage. The case where an optical sensor is provided has been described as an example. However, the present invention is not limited to the detection of the current flowing through the electric circuit L and the voltage applied to the electric circuit L, and can be widely applied to the detection of current and voltage in general. Needless to say, it can be used not only for electric power equipment but also for detecting current and voltage of smaller converters and electric circuits.

1 is a block diagram showing a schematic configuration of a protective relay system according to an embodiment of the present invention. It is a figure for demonstrating the principle of a Faraday sensor element. It is a figure which shows the specific structure of the optical system of the protection relay system 110. 3 is a block diagram showing a configuration of a signal processing unit 124. FIG. It is a block diagram which shows schematic structure of the protection relay system by another embodiment of this invention. It is a figure which shows the specific structure of the optical system of the protection relay system 210. It is a block diagram which shows schematic structure of the protection relay system by another embodiment of this invention. It is a figure which shows the specific structure of the optical system of the protection relay system 310. 3 is a block diagram illustrating a configuration of a signal processing unit 324. FIG. It is a block diagram which shows schematic structure of the conventional protection relay system. It is a block diagram which shows schematic structure of the conventional protection relay system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 Protection relay system 111 Optical sensor 111c Branching optical system 112 Relay apparatus 113 Optical line 121 Light source 124 Signal processing part 131,132 Photodiode 133 Normalization processing part 134 Averaging processing part L Electric circuit

Claims (8)

In a protective relay system comprising a detection device and a relay device,
The detection device comprising an optical sensor;
An optical line connecting the detection device and the relay device;
A signal processing unit that performs photoelectric conversion of a detection light signal transmitted from the detection device;
A protective relay system comprising:   The protective relay system according to claim 1, wherein the optical sensor is a sensor that detects a current flowing through the measurement target by detecting a magnetic field generated by the current flowing through the measurement target.   The protective relay system according to claim 1, wherein the optical sensor is a sensor that detects a voltage applied to the measurement target by detecting an electric field generated by the voltage applied to the measurement target.   The protective relay system according to any one of claims 1 to 3, wherein the relay device includes a light source that emits an optical signal.   The protection relay system according to claim 4, wherein the optical line propagates the optical signal emitted from the light source to the optical sensor along with the propagation of the detection optical signal. The optical sensor includes a branching optical system,
The protective relay system according to any one of claims 1 to 5, wherein the optical line individually propagates each of the detection optical signals branched by the branch optical system. The signal processing unit includes first and second photoelectric conversion elements that convert each of the detection optical signals input via the optical line into electrical signals;
A normalization processing unit that extracts a DC component and an AC component from the electrical signals converted by the first and second photoelectric conversion elements, respectively, and obtains a modulation degree signal obtained by normalizing the AC component with the DC component;
An averaging processing unit that performs an averaging process by obtaining a difference between the modulation degree signals obtained by the normalization processing unit. The protective relay system according to any one of 6. The signal processing unit includes a photoelectric conversion element that converts the detection optical signal input via the optical line into an electrical signal;
A normalization processing unit that extracts a DC component and an AC component from the electrical signal converted by the photoelectric conversion element, and obtains a modulation degree signal obtained by normalizing the AC component with the DC component;
The protective relay system according to any one of claims 1 to 6, further comprising:

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