JP4065243B2 - Optical CT with failure judgment function - Google Patents

Description

  The present invention relates to an optical CT having a failure determination function, and more particularly to an optical CT having a failure determination function applied to power equipment and power equipment.

  In the event of an abnormality in power equipment or power equipment such as transformers installed in substations, etc., these equipment and equipment are protected and their operation is stopped to prevent the spread of accidents. A protective relay system is installed.

  FIG. 3 shows a typical example of this type of protective relay system. The protective relay system shown in the figure is connected to the transformer 2 attached to the main body of the power equipment 1, the converter 3 connected to the output side of the transformer 2, and the output side of the converter 3. And a protective relay 4.

  The transformer 2 measures the current and voltage of the power equipment to be protected. The converter 3 converts the level of the detection signal of the transformer 2 and outputs it to the protective relay 4. The protective relay 4 receives the output signal of the converter 3, performs necessary arithmetic processing, and determines the abnormality of the power equipment 1 from the result.

  If it is determined by the protective relay 4 that an abnormality has occurred in the power equipment 1, a trip signal is sent to operate the circuit breaker and the like, thereby stopping the operation of the power equipment 1. However, such a conventional protective relay system for the power equipment 1 has the following problems.

  That is, the conventional protective relay system uses a large number of electronic components for the arithmetic circuit of the protective relay 4 and the like, and thus becomes very expensive. In addition, in detecting the current and voltage of the transformer 2, the winding type is easily subject to disturbances such as an external magnetic field, and it is difficult to take a surge countermeasure for the protective relay system.

  Furthermore, since the current and voltage of the power equipment 1 are large, the transformer 2 for detecting these becomes large and heavy, and there has been a demand for a small and lightweight system as a whole.

  The present invention has been made in view of the above-described conventional problems, and is inexpensive and can simplify the surge countermeasures, and also has a failure determination function that can achieve a reduction in size and weight of the system. To provide CT. Another object of the present invention is to provide an optical CT that enables practical failure determination.

In order to achieve the above object, the present invention provides an input side and an output side optical fiber sensor that is installed around the outer periphery of a plurality of conductors connected to a power facility and individually measures input / output currents of each conductor, a light source, An electronic circuit unit including a photoelectric converter, a signal processing unit, and a failure determination unit, and between the light source and the optical fiber sensor, between the optical fiber sensors, and the optical fiber sensor and the photoelectric converter, Are provided in series, and the signal processing unit obtains the sum of the current values measured by the optical fiber sensor, and from the sum of the current values, the failure determination unit determines the abnormality of the power equipment. the optical CT with fault determination function of determining, in the optical fiber transmission path, the polarization of the light emitted from the input optical fiber sensor, the output-side light is converted into unpolarized light fa It provided depolarizer to be incident on Basensa.
According to the optical CT having a failure determination function configured as described above, an optical fiber sensor is installed around the outer periphery of a plurality of conductors connected to the power facility, and input / output currents of the respective conductors are individually measured.
Current measurement using an optical fiber sensor measures the Faraday rotation angle at which the polarization of the light propagating in the optical fiber sensor rotates in accordance with the magnitude of the current magnetic field. In this case, output distortion due to magnetic saturation of the iron core does not occur.
In addition, current measurement is performed with an optical fiber sensor, and the optical fiber transmission line is connected in series between the light source and the optical fiber sensor, between the optical fiber sensors, and between the optical fiber sensor and the photoelectric converter. The entire system can be reduced in size and weight, and surge countermeasures can be simplified.
Further, in the present invention, based on Kirchhoff's first law, the signal processing unit obtains the sum of the current values measured by the optical fiber sensor, and the failure judgment unit judges the abnormality of the power equipment from the sum of the current values. Therefore, the arithmetic processing is also simplified.
In this case, in the present invention, after all the Faraday rotation angles are added, the photoelectric converter converts the light amount into a light amount change, so that it is possible to ensure the calculation accuracy for the large current concentration.
According to the above configuration, since the depolarizer is provided in the optical fiber transmission line to convert the polarization of the outgoing light from the input side optical fiber sensor into non-polarized light and enter the output side optical fiber sensor. It is possible to prevent a decrease in measurement accuracy due to a change in polarization in the road.
In the present invention, in the optical CT having a failure determination function, the depolarizer includes an analyzer provided at an output end of the input side optical fiber sensor and a polarizer provided at an input end of the output side optical fiber sensor. In the optical fiber transmission line.
In the present invention, in the optical CT having a failure determination function, the optical fiber sensor is connected to the power equipment, and is installed on the outer periphery of a pair of conductors through which input and output currents of the power equipment flow. And an output-side optical fiber sensor, the light propagation direction in the input-side optical fiber sensor and the direction of the magnetic field created by the input current are matched, and the light propagation direction in the output-side optical fiber sensor The direction of the magnetic field generated by the output current can be set in a direction opposite to that of the output current.
According to this configuration, the optical fiber sensor has an input side and an output side optical fiber sensor installed on the outer periphery of a pair of conductors that are connected to the power facility and through which the input and output currents of the power facility flow. The direction of light propagation in the optical fiber sensor and the direction of the magnetic field generated by the input current are matched, and the direction of light propagation in the output-side optical fiber sensor and the direction of the magnetic field generated by the output current are set in opposite directions. Therefore, when two input / output conductors are connected to a power facility, a practical failure determination is possible by using an existing optical fiber sensor or the like within a relatively small current value range. become.

  According to the optical CT having the failure determination function according to the present invention, it is inexpensive and simplification of surge countermeasures can be achieved, and furthermore, the system can be reduced in size and weight.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an outline of a basic configuration of an optical CT having a failure determination function according to the present invention.

The optical CT having the failure determination function shown in FIG. ₁ includes a plurality of optical fiber sensors ₁₀₁ to ₄ , an optical fiber transmission line 12, and an electronic circuit unit 14. The optical fiber sensors _{101 to 4} are installed so as to go around the outer circumferences of the plurality of conductors 18 connected to the power equipment 16 to be protected.

Each optical fiber sensor _{10 1-4} measures the output current value _{I 1 to 4} of the conductors 18, respectively. Measurement principle of the current values I _{1 to 4} of the optical fiber sensor 10 _1-4 when propagating light in the optical fiber sensor 10 _1-4 which is orbiting installed on the outer periphery of the conductor 18, the polarization of light propagating However, the Faraday rotation angle is measured to determine the current values I1 to _I4 flowing through the conductors 18.

The electronic circuit unit 14 includes a light source 14a, a photoelectric converter 14b, a signal processing unit 14c, and a failure determination unit 14d. Optical fiber transmission line 12 includes a light source 14a and between the first-th optical fiber sensor 10 _1, the second after the optical fiber sensor _{10 2-4} between each other and the end portion of the optical fiber sensor 10 ₄ and the photoelectric The converter 14b is provided in series with each other.

The signal processing unit 14c receives the output signal of the photoelectric converter 14b and obtains the sum of the Faraday rotation angles with respect to the current values I1 to ₄ measured by the optical fiber sensors ₁₀₁ to ₄ . The failure determination unit 14d receives the output signal of the signal processing unit 14c and determines a failure of the power equipment 16 based on Kirchhoff's first law. That is, according to Kirchhoff's first law, the sum S = k (I ₁ + I ₂ + I ₃ + I ₄ ) of the current values I _{1 to 4} flowing into and out of the power facility 16 becomes zero if there is no abnormality.

Therefore, the failure determination section 14d, when the sum of the current value I _{1 to 4} has become non-zero, it is determined that there is an abnormality and sends a signal to that effect to the outside, based on the outgoing signal power The facility 16 is stopped.

According to the optical CT having the failure determination function configured as described above, the polarization of the light propagating through the optical fiber sensors ₁₀₁ to ₄ has a Faraday rotation angle that rotates according to the magnitude of the current magnetic field. Since the current values I1 to _I4 are obtained by measurement, output distortion caused by magnetic saturation of the iron core does not occur even when a large current including a DC component at the time of an accident flows.

Further, performs current measured by the optical fiber sensor _{10 1-4,} an optical fiber transmission path 12, the light source 14a and the first between the optical fiber sensor 10 _1, of the second subsequent optical fiber sensor _{10 2-4} between each other and since the series connection between the last optical fiber sensor 10 ₄ and the photoelectric converter 14b, consists of a portion of all the optical fibers to be laid in the power plant 16, the entire system compact, lightweight achievement In addition, surge countermeasures can be simplified.

Further, based on Kirchhoff's first law, the signal processing unit 14c obtains the sum of the current values I1 to ₄ measured by the optical fiber sensors ₁₀₁ to ₄ , and determines the failure from the sum of the current values I1 to _I4. Since the abnormality of the power equipment 16 is determined by the unit 14d, the arithmetic processing is also simplified.

  In this case, after all the Faraday rotation angles are added, the photoelectric converter 14b converts the light amount into a change in light amount, so that it is possible to ensure the calculation accuracy for large current concentration.

  FIG. 2 shows an embodiment of an optical CT having a failure determination function according to the present invention. The same or corresponding parts as those in the basic configuration are given the same reference numerals and the description thereof is omitted. Only the feature points will be described.

In the embodiment shown in the figure, the present invention is applied when _two input and output conductors 18 ₁ and 18 ₂ are connected to the power equipment 16 to be protected. The outer periphery of the input conductor 18 _1, the input current input side optical fiber sensor 10a for measuring the I ₁ is disposed on the outer periphery thereof, k is the propagation direction (FIG. 2 of the light in the optical fiber sensor 10a, (the direction is indicated by l) is provided so as to coincide with the direction of the magnetic field generated by energization.

The outer periphery of the output conductor 18 _2, the output side optical fiber sensor 10b for measuring the output current I2 is disposed on the outer periphery thereof, k is in the light propagation direction in the optical fiber sensor 10b (FIG. 2, l Is indicated so as to be opposite to the direction of the magnetic field generated by energization.

  A polarizer 22 is disposed on the incident side of each of the optical fiber sensors 10a and 10b, and a λ / 2 plate 23 and an analyzer 24 are disposed on the exit side. Between the light source 14a and the polarizer 22 provided on the input side of the input side optical fiber sensor 10a, between the analyzer 24 provided on the output side of the input side optical fiber sensor 10a and the input side of the output side optical fiber sensor 10b. A single mode optical fiber or a polarization-maintaining fiber is connected between the provided polarizer 22 and between the analyzer 24 provided on the output side of the output side optical fiber sensor 10b and the photoelectric converter 14b. These constitute the optical transmission line 120a.

  A depolarizer 50 is provided in the optical transmission line 120a. The depolarizer 50 is interposed between the analyzer 24 provided on the output side of the input side optical fiber sensor 10a and the polarizer 22 provided on the incident side of the output side optical fiber sensor 10b. The polarized light of the light emitted from the fiber sensor 10a is converted into non-polarized light and is incident on the output side optical fiber sensor 10b.

  When such a depolarizer 50 is interposed, in the optical transmission between the optical fiber sensors 10a and 10b, which are current detection units, when the propagating light has a polarization characteristic, the incident on the output side optical fiber sensor 10b. The amount of light incident by the polarizer 22 provided on the side is greatly reduced, and the amount of light loss from the optical fiber sensor 10b is considered to increase. Therefore, the outgoing light from the optical fiber sensor 10a enters the depolarizer 50. After making it non-polarized light, it was made to enter the optical transmission line 120a composed of a transmission single mode fiber or a polarization maintaining fiber.

Next, the operation principle of the optical CT having the above configuration will be described. In the optical CT shown in FIG. 2, the light P ₀ from the light source 14a is made into linearly polarized light by the polarizer 22 of the optical fiber sensor 10a, when incident linearly polarized light to lead glass fiber made of the optical fiber sensor 10a, While the incident light passes through the fiber, it undergoes rotation θ ₁ of the polarization plane due to the Faraday effect caused by the magnetic field generated by the energizing current I ₁ .

The relationship between the energization current I ₁ and the rotation θ ₁ of the polarization plane is expressed by the equation (4-1), where Verde constant is ν.
θ ₁ = νI ₁ (4-1)
The output light P ₁ of the optical fiber sensor 10 a is intensity-modulated from the half-wave plate 23 and the analyzer 24 in the form of a pulsating flow of a DC component + AC component if the current to be measured is an AC, if the rotation of the polarization plane is AC. The emitted light P ₁ is expressed by the following equation (4-2).

_{P 1 = P 0/2 (} 1 + sin2θ 1) = P 0/2 {1 + sin (2νI 1 sinωt)} ......... (4-2)
Here, ω (= 2πf), f: frequency of current to be measured, t: time The intensity-modulated light from the optical fiber sensor 10a is converted into non-polarized light by the depolarizer 50.

  Next, the intensity-modulated non-polarized light is guided to the optical fiber sensor 10b by the optical transmission line 120a formed of a single mode fiber or a polarization-maintaining fiber, and the polarizer 22 disposed on the incident side thereof, It becomes light whose intensity is modulated by linearly polarized light.

By entering the light to lead glass fiber made of the optical fiber sensor 10b, similarly to the optical fiber sensor 10a, the incident light, while passing through the fiber, the polarization plane by the Faraday effect by the magnetic field generated by the applied current I ₂ The rotation θ ₂ is received.

As a result, outgoing light P ₂ from the optical fiber sensor 10b, similarly to the optical fiber sensor 10a becomes intensity modulated light is represented by the following formula (4-3).
_{P 2 = P 1/2 (} 1 + sin2θ 2)
_{= P 0/4 {1 +} sin (2νI 1 sinωt)} {1 + sin (2νI 2 sinωt)}
_{= P 0/4 {1 +} sin (2νI 1 sinωt) + sin (2νI 2 sinωt) + sin (2νI 1 sinωt) sin (2νI 2 sinωt)} .................. (4-3)

Here, if the optical fiber sensor 10a, mounted so as to match the direction of light propagating in the magnetic field direction and lead glass fibers produced by the applied current I _1, the formula (4-3), electric current I ₂ of current direction is opposite the direction of the applied current I _1.
Outgoing light _{P 2} from the optical fiber sensor 10b thus becomes as shown in Equation (4-3.a).

_{P 2 = P 1/2 (} 1 + sin2θ 2)
_{= P 0/4 {1 +} sin (2νI 1 sinωt)} {1-sin (2νI 2 sinωt)}
_{= P 0/4 {1 +} sin (2νI 1 sinωt) -sin (2νI 2 sinωt) -sin (2νI 1 sinωt) sin (2νI 2 sinωt)} .................. (4-3.a)

Here, when the energization currents I ₁ and I ₂ are not large currents, sin (2νI ₁ sinωt) sin (2νI ₂ sinωt) in the equation (4-3.a) is a very small value,
As a result, sin (2νI ₁ sinωt) sin (2νI ₂ sinωt) ≈0 can be set. Therefore, Formula (4-3.a) can be expressed as Formula (4-4).
_{P 2 = P 0/4 {} 1 + sin (2νI 1 sinωt) -sin (2νI 2 sinωt)} ......... (4-4)

_P 0/4 of the formula (4-4), the DC component of the intensity-modulated _{light, P 0/4 {sin (} 2νI 1 sinωt) -sin (2νI 2 sinωt)} is the AC intensity modulated light Can be expressed in ingredients.

Outgoing light _{P 2} of the formula (4-4) is converted into an electric signal by the photoelectric converter 14b in the figure, then, _P 0/4 by LPF (low pass filter) of the signal processing circuit 14c, HPF (high-pass _P by the filter) 0/4 {sin (2νI 1 sinωt) -sin (2νI 2 sinωt)} is taken, the output S obtained by dividing these by the equation (4-5) is obtained.

S = AC component / DC component _{= P 0/4 {sin (} 2νI 1 sinωt) -sin (2νI 2 sinωt)}
P _0/4
= Sin (2νI ₁ sinωt) −sin (2νI ₂ sinωt) (4-5)
Here, in the sine function, when the angle Φ is small, the approximation of Expression (4-6) is established.
sinΦ = Φ ……………… (4-6)

When the energization current is small, the expression (4-5) satisfies the expression (4-6). Therefore, the equation (4-5) becomes the equation (4-7), and the output S includes a difference component between the input current I ₁ and the output current I _2. The failure determination of the facility 16 becomes possible.

S = 2νI ₁ sinωt−2νI ₂ sinωt
= 2νsinωt (I ₁ −I ₂ ) (4-7)

In the embodiment shown in FIG. 2, an example is shown in which the depolarizer 50 is provided in the optical transmission line 120a and the polarization characteristics during transmission in the optical fiber sensors 10a and 10b are compensated. In this case, although the detection accuracy is slightly lowered, when the two input / output conductors 18 ₁ and 18 ₂ are connected to the power facility 16, the current value is within a relatively small range. By using an existing optical fiber sensor or the like, failure determination can be performed practically and inexpensively.

  According to the optical CT provided with the failure determination function according to the present invention, it can be effectively used for failure determination of power equipment and power equipment.

It is explanatory drawing of the basic concept of optical CT provided with the failure determination function concerning this invention. It is a whole block diagram which shows one Example of optical CT provided with the failure determination function concerning this invention. It is explanatory drawing of the conventional protection relay system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical fiber sensor 12 Optical fiber transmission line 14 Electronic circuit part 14a Light source 14b Photoelectric converter 14c Signal processing part 14d Judgment part 16 Electric power equipment

Claims (3)

Input and output side optical fiber sensors that are installed around the circumference of multiple conductors connected to power equipment and individually measure the input / output current of each conductor, light source, photoelectric converter, signal processing unit, and failure determination unit And an optical circuit transmission line for connecting in series between the light source and the optical fiber sensor, between the optical fiber sensors, and between the optical fiber sensor and the photoelectric converter, respectively. An optical CT having a failure determination function for obtaining a sum of current values measured by the optical fiber sensor in the signal processing unit and determining an abnormality of the power equipment in the failure determination unit from the sum of the current values In
A failure determination function characterized in that a depolarizer is provided in the optical fiber transmission line to convert the polarized light of the light emitted from the input side optical fiber sensor into non-polarized light and to enter the output side optical fiber sensor. Optical CT provided. In optical CT provided with the failure determination function of Claim 1,
The depolarizer is provided in the optical fiber transmission line between an analyzer provided at an output end of the input side optical fiber sensor and a polarizer provided at an incident end of the output side optical fiber sensor. An optical CT having a failure determination function characterized by that . In optical CT provided with the failure determination function according to claim 1 or 2,
  The optical fiber sensor has an input side and an output side optical fiber sensor that are connected to the power equipment and are installed on the outer periphery of a pair of conductors through which the input and output currents of the power equipment flow.
  While making the propagation direction of light in the input side optical fiber sensor coincide with the direction of the magnetic field created by the input current,
  An optical CT provided with a failure determination function, wherein a propagation direction of light in the output side optical fiber sensor and a direction of a magnetic field generated by the output current are set to be opposite to each other.

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