WO2003069754A1

WO2003069754A1 - Protective relay apparatus comprising photoelectriccurrent sensor

Info

Publication number: WO2003069754A1
Application number: PCT/JP2003/001662
Authority: WO
Inventors: Takafumi Ito; Yoshifumi Chida; Matsuyoshi Kato; Yasuhisa Yamada; Yoichiro Tashiro; Kiyoshi Kurosawa; Kenji Ohkawara
Original assignee: Takaoka Electric Mfg. Co., Ltd.; Tokyo Electric Power Company
Priority date: 2002-02-18
Filing date: 2003-02-17
Publication date: 2003-08-21
Also published as: JPWO2003069754A1; AU2003211341A1; CN1623261A; CN100399660C; JP3802028B2

Abstract

A protective relay apparatus comprising two photoelectriccurrent sensors installed at both ends of a protected section of a power system which can not only detect an internal fault but also discriminate an external fault from an internal fault without its misreading even if the fault current is one with superposed a DC component. A first photoelectriccurrent sensor (1) and a second photoelectriccurrent sensor (2) are installed at both ends of a protected section (9) of a power system. Optical fiber transmission lines (3a to 3d) series-connect a light source (11), a first photoelectriccurrent sensor (1), a second photoelectriccurrent sensor (2), a first optical signal processing section (4a), and a second optical signal processing section (4b). An action quantity operating means (6a), a suppression quantity operating means (6b), and an action rate operating means (7) determine an action quantity, a suppression quantity, and an action rate from a differential current signal from the first optical signal processing section (4a) and a sum current signal of the second optical signal processing section (4b). Even if a judging means (8) detects that the action quantity over a set value, the fault is judged to be an external fault if the action rate is below a constant, thereby preventing an unnecessary action of the relay.

Description

Specification

Protective relay device using photocurrent sensor

The present invention relates to a protective relay for measuring and monitoring a current flowing in a conductor of a power facility by utilizing the Faraday effect.

Background art

Conventionally, in a protective relay in a power system, a current signal of a device conductor detected by a current transformer is transmitted to the protective relay, and the protective relay performs calculation and determination for failure determination. . In order to reduce the cost and weight of this protective relay device, a protective relay device using a photocurrent sensor with a differential operation function has been proposed instead of the current measurement method using a conventional wound-type current transformer. The application has been filed in the form of “Open 200 0—5 9 9 8 7” and Japanese Patent Application No. 1 1—2 2 4 8 2 1.

As shown in FIG. 6, for example, a protection relay device using a conventional photocurrent sensor includes a first photocurrent sensor 1 including a polarizer 14, a Faraday element 11, and an analyzer 15, and a first photocurrent sensor. Second photocurrent sensor 2 configured in the same way as sensor 1, optical fiber transmission lines 3a, 3b, 3c, light source 12, photoelectric converter 16, high-pass filter circuit 17, low-pass filter It comprises an optical signal processing section 4 a composed of a circuit 18 and a divider 19, a power frequency component difference current detecting means 5 d, and a judging means 8.

The first photocurrent sensor 1 and the second photocurrent sensor 2 are provided at both ends of the protection section 9 of the power system. Here the current first photocurrent sensor 1 detects the i physician second optical current sensor 2 a current detected a i _2, the code together inflow direction to the protected section 9 of the electric power system + The outflow direction is one. The direction of propagation of light in the first photocurrent sensor 1 is provided so as to coincide with the direction of the magnetic field generated by the current i detected by the first photocurrent sensor 1, and the second photocurrent The light propagation direction in the sensor 2 is provided so as to match the magnetic field generated by the current i ₂ detected by the second photocurrent sensor 2.

Light P emitted from a light source 12 that emits light of a predetermined wavelength. Reaches the first photocurrent sensor 1 via the optical fiber transmission line 3a. Light P from light source 1 2. Is the first light The light becomes linearly polarized light by the polarizer 14 of the current sensor 1, and the linearly polarized light enters the Faraday element 11. The incident light is subjected to the Faraday effect by the magnetic field generated by the current it, and the plane of polarization rotates by an angle in proportion to the magnitude of the current ii. The relationship between the current i detected by the first photocurrent sensor 1 and the rotation angle Θ of the polarization plane is when the Verde constant is V.

Θ _X = V- i ₁

Becomes The incident light is further converted into light in which the rotation angle 0 of the polarization plane is modulated by the analyzer 15 in the first photocurrent sensor 1. At this time, the analyzer 15 is preferably installed at an angle of plus 45 ° or minus 45 ° with respect to the polarizer 14, and the emitted light of the first photocurrent sensor 1 is x, y by the analyzer 15 The light is divided into two components, _Plx and _Ply , in the direction.

Ρ _αχ = (1/2) Ρ ₀ (1 + sin2 Θ 丄)

= (1/2) Ρ ₀ (1 + sin2 Vi,)

P _ly = (l / 2) P. (1—sin 2 Θ!)

= (1/2) P ₀ (1 -sin2 Vi _x ) • • • • (2 b)

In the conventional apparatus, either it is used only one of the optical signals, will be described here light P _lx Te situ.

Assuming that the current i detected by the first photocurrent sensor 1 is a sine wave AC signal, the outgoing light P _{lx of the} first photocurrent sensor 1 is represented by the following equation.

P _lx = (l / 2) P. {1 + sin (2Λ 2 V-I ^ ίηω t)} · (4) where I i is the effective value of the inflow current, ω (= 2 π f) is the angular frequency, and f is the power supply frequency. is there.

The output light _{Plx of the} first photocurrent sensor 1 is guided to the optical fiber transmission line _3b and reaches the second photocurrent sensor 2. Outgoing light P _lx, the second receiving the Faraday effect due to the magnetic field optical current sensor 2 is generated by the current i ₂ I ₂₈ ΐηω t) for detecting a current i ₂ of the plane of polarization in proportion to the magnitude angle 0 ₂ Just rotate. The light emitted from the second photocurrent sensor 2 is again divided by the analyzer 15 into two component lights P _2x and P _2y in the x and y directions, and are expressed by the following equation. _{P 2x - (l / 2)} P lx (l + sin20 2)

= (1/4) P. (1 + sin2 Θ i) (1 + sin2 Θ ₂ )

= (1/4) P. (L + sin2V * i 丄) (1 + sin2 V i ₂ ) ·-(5 a)

P _2y = (l / 2) P _lx (1 sin 2 Θ ₂ )

= (1/4) P ₀ (1 + sin2 Θ _x ) (1 -sin2 Θ ₂ )

= (1/4) P ₀ (1 + sin2 V-i (1- _S in2 V-i ₂ ))-(5 b) where P _lx of the two outputs of the first photocurrent sensor 1 is Since P2x is selected, P _2x having the same polarization direction as the outgoing light of the first photocurrent sensor 1 is used as the outgoing light of the second photocurrent sensor 2. When _Ply is selected from the outputs, _P2y is used as the output light of the second photocurrent sensor 2.

The light P _2x emitted from the second photocurrent sensor 2 is guided to the optical fiber transmission line 3 c and enters the photoelectric converter 16, where it is converted into an electric signal. The DC component and the AC component are separated by 18, and the AC component is divided by the DC component in the divider 19 to obtain a difference current output S _2x by the photocurrent sensor. Here, the method of dividing by the DC component by the divider 19 is used in order to compensate for the loss of light quantity when the optical signal is transmitted. The difference current output S _2x by the photocurrent sensor is represented by the following equation.

S _2x = A (P _2x of the AC component) / (P DC component of _{2x) · · · '(6} ) the difference between the current output S _{2 x} by the optical current sensor obtained here, the first optical current sensor 1 There will be described below in that it has a detected current i E and a second difference current der Ru information i Interview + i ₂ of the current i ₂ photocurrent sensor 2 has detected. In addition, the difference current to the protection section 9 of the power system is indicated as i i + i ₂ because both the sign of i ₂ and the outflow direction to the protection section 9 of the power system are defined as 10 and 1, respectively. It depends.

If the current it 2 detected by the first photocurrent sensor 1 and the current i2 detected by the second photocurrent sensor ₂ are small currents,

sin29 ^ 26 ^ sin2 θ ₂ = 2 θ ₂ (7)

Holds, and equation (5a) is

P _2X = (1/4) P. (1 + 2V. I _X + 2V-i ₂ )

= il / 4) P ₀ {1 + 2 ^ 2 V (I τ + I ₂ ) sinc t} ' Becomes Substituting equation (8) into equation (6) gives

S _2x = 2 2V (I! + I ₂ ) sinot ...- (9), and the difference current output S _2x by the photocurrent sensor is proportional to the difference current i! + I ₂ to the protection section 9 of the power system. Value.

However, Equation (9) holds in a small current region where Equation (7) holds, and does not hold in a high current region.

The present inventors, the Japanese Patent Application No. flat 11-224821 as a protective relay device using an optical fiber sensor capable of measuring the difference current i E + i ₂ to the protected section 9 of the electric power system even in a large current region Filed.

That is, when a large current flows such that Expression (7) does not hold, the output light P _{2 x} of the _second photocurrent sensor 2 expressed by Expression (5a) is

P _2x = (l / 4) P. U + sin (2 2V 'sinco t)} X

{1 + sin (2 "2 VI ₂ sino t)}

It is expressed as

Here is decomposed for each frequency component by sin a _{(2 2V * I n sinc t} ) deployed off one Fourier series, expressed in the following equation (11).

sin (2 V _r I χβίηω t) =

Υ [2 · J _{2m + 1} (2 V _r I i) · sin {(2m + 1) ω t}] · · · · (11)

= 0

Where J _k (a) is the k-th Bessel function

(11) and ignored as a small cubic following sections of Formula, in order to show schematically the subsequent expression, defined as showing the Ap A ₂ in (12 a) (l 2 b) expression.

A _x = 2 J! (2 ^ 2 V-) · · ·-(12 a)

A ₂ = 2 J _X (2> T2 VI ₂ ) '(12 b)

Here AA ₂ is multiplied by a Verdet constant I ₂ have the effective value I of the current is obtained by substituting the primary Besse 1 function, the current i _n (3) with a sinusoidal AC signal as shown in the formula If there is, time is a constant.

In this case, equation (10) becomes

t} {1 + 2 A ₂ sinto t} ·-(1 c) Can be represented by

Expanding equation (12c) and using the trigonometric formula sin ² Φ = (1/2) {1 -cos2},

ω U

• '' '(I 2d)

Becomes At this time, the difference current output S _2x by the photocurrent sensor can be expressed as in equation (13a) by substituting equation (12d) into equation (6). To show where the subsequent expression briefly, are replaced by (12 a), (12 b ) formula A have A ₂ shown in (13 b), BB ₂ depicted in (13 c).

S _2x = B isinco t + B ₂ cos 2 ω t

B ₁ = 2 (A ₁ + A ₂ ) / (1 + 2A ₁ A ₂ ) (13 b)

B ₂ = 2A ₁ A ₂ / (1 + 2A ₁ A ₂ ) · · ·-(13 c) where BB ₂ is a constant with respect to time.

As shown in equation (13a), the difference current output S _2x by the photocurrent sensor is the frequency component of the difference current i + i ₂ to the protection section 9 of the power system shown in the first term, that is, the power supply frequency In addition to the component, it consists of the term of the frequency component twice the power frequency shown in the second term. Here, we try to evaluate the term of the power frequency component of Eq. (13b) by calculation. In the 66 kV to 154 kV power system, the current flowing into protection section 9 is assumed to be 33 kA or less. In this case, using the Verdet constant ^{V = 3. 93X 10- 6 [rad} / A] of the lead glass fiber-type optical current sensors of wavelength 155 onm. Using these values,

'An approximation of In holds. At this time, equation (13b) can be expressed as equation (13d).

As a result of the calculation, the approximation error is 1% or less at an effective current of 24 kA and 2% or less at an effective value of 33 kA or less, and a lead glass fiber type photocurrent sensor with a wavelength of 155 Onm is obtained. Considering the possibility that the used protective relay can be applied to the failure judgment calculation available.

Therefore, equation (13a) shows that at a current of 33 kA or less, at the same frequency component as the power supply frequency of the differential current output S _{2 x} by the photocurrent sensor, the differential current i Although an output proportional to E + i _2, which means that twice the frequency components of the power supply frequency is generated as an error component.

The power supply frequency component difference current detection means 5 removes twice the frequency component from the difference current output S _{2 x} by the photocurrent sensor, and the output is led to the judgment means 8 to protect the power system. operate on the differential current i E + i ₂ to the protective relay device is formed.

In the above description of the related art, it is assumed that the current signal is a sine wave AC signal. However, it is necessary to consider that when a short circuit accident occurs in the power system, the current signal becomes a signal that is superimposed on the DC component and transiently attenuated. At this time, when the largest DC component is superimposed, that is, the fault current with 100% DC component superimposed is expressed by the following equation.

i

t} · · · · (1 4)

Here, τ is an attenuation time constant determined from the ratio of the reactance and the resistance of the power system. Even if the transiently attenuated current signal represented by equation (14) is substituted into equations (5a) and (6), it is divided into power supply frequency components as shown in equation (13a). It cannot be represented. Therefore, the effect of the error component included in the difference current output S _{2 x} of the photocurrent sensor on the protection case 9 of the power system for the accident cases outside the protection zone and the accident within the protection zone Think.

FIG. 2 is a system diagram for explaining the operation of the protective relay using the photocurrent sensor. As the accident points in protection section 9 of the power system, fl and f3 are accidents outside the protection section, and f2 are accidents in the protection section. Hereinafter, an accident outside the section of protection section 9 of the power system is referred to as an external accident, and an accident within the section of protection section 9 of the power system is referred to as an internal accident.

In FIG. 2, the first photocurrent sensor 1 and the second photocurrent sensor 2 are respectively installed at both ends of the protection section 9 of the power system, and the light source is provided by the optical fiber transmission lines 3a to 3d. 12, connected to the first optical signal processing unit 4a and the second optical signal processing unit 4b. Here, the first photocurrent sensor 1 detects the current ii, and the second photocurrent Sensor 2 for detecting the current i _2.

First, consider the case where an external accident has occurred. If an external accident occurs, the current i, "

ii ₂ (t) '"'" (! 5)

Holds. Substituting equations (14) and (15) into equation (5a) gives

P _2x = (l / 4) P. {1 + sin2 V · i ^ t)} {1 -sin2 V · i _x (t)}. Here, for simplicity,

sin {2 V · i _x (t)} ^ 2 V · i ^ t)

Then, substituting equation (14), equation (5a) becomes

P _2x = (l / 4) P ₀ [1-8V ² i! ² {e ⁽ " ^{t / r)} -οοβω t} ² ]

_{= (1/4) Ρ 0 [1-8} V 2 i 2 {e! (- 2 t / ^{Te) + 2 · e (- t} / r) .coso t-1/2 + 1/2 cos2 ω t }] · · · · (16)

Becomes That is, in the conventional technology, if the fault current is a sine-wave AC signal, the power supply frequency component of the difference current i + i ₂ to the protection section 9 of the power system should be 0 at the time of an external fault. In the case of a transiently attenuated signal with a superimposed component, an error signal is generated until the DC component is attenuated as shown in equation (16). Fig. 7 is a diagram for explaining that if an external fault occurs and the fault current is a DC component superimposed, unnecessary operation of the protective relay may occur with the conventional technology. The values of the fault current and the optical fiber constants shown below were substituted into equations (14), (5a) and (6), and the signal values at each section were calculated.

Fig. 7 (a) shows the fault current signal in which the DC component expressed by equation (14) is superimposed in the case of an external fault, and Fig. 7 (b) shows the second photocurrent sensor at this time. Optical signal from 2 P _2x ZP. And FIG. 7 (c) a differential current output S ₂ x by the optical current sensor, Fig. 7 (d) the effective value R _2x power frequency component of the differential current output S _2x by the optical current sensor obtained, respectively it Things. Here the optical current sensor 1, 2 is a lead-glass Sufaiba type fiber-optic current sensor having a wavelength of 1550 nm, the Verdet constant V is used ^{3. 93X 10- 6 [r ad /} A]. The magnitude of the fault current I is 33 kA rms, the power supply frequency is 5 OHz, and the time constant is 50 ms. As the means for determining the effective value R _2x power frequency of the differential current output by the optical current sensor, digital in a digital relay circuit Filter 'Effective value calculation circuit used. Since this is a well-known technique, we will only introduce its algorithm here.

Electrical angle 30 degrees

Digital fill DF _lf = (l—Z— ⁶ ) (1 + Z ~ ¹ + Z- ² + Z- ³ )

—— 2 „.

Then n—3 then n then n 6

Next, in order to compare with the case of a sine wave AC signal, Fig. 7 (e) shows the fault current when the fault current was a sine wave AC signal expressed by equation (3). Light signal P _2x / P from the second photocurrent sensor ₂ . Fig. 7 (f) shows the difference current output _S2x by the photocurrent sensor in Fig. 7 (g), and Fig. 7 (h) shows the effective value of the power supply frequency component of the difference current output _S2x by the photocurrent sensor. .

As shown in Fig. 7 (h), if the fault current is a sine-wave AC signal in an external fault, a short-time error signal is generated immediately after the fault (equivalent to a peak value of 4kA for 0.01 seconds). Is not reached. On the other hand, in the case of a transient current signal in which a DC component is superimposed on the fault current, an error signal is generated for a time that cannot be ignored as shown in Fig. 7 (d) (equivalent to a peak value of 20 kA, 0.2 Seconds). This is because the power supply frequency component is represented as an error signal until the DC component is attenuated as shown in Eq. (16).

Next, the operation of a protective relay using a photocurrent sensor according to the prior art in an internal accident will be described with reference to FIG. FIG. 7 (i) shows a signal in which an internal fault has occurred in the system shown in FIG. 2 and the fault current is expressed by the equation (14) with a DC component superimposed on 100%. Optical signal from sensor 2 P _2x ZP. Figure 7 (j) shows the difference current output S _2x by the photocurrent sensor in Figure 7 (k), and Figure 7 (1) shows the effective value of the power supply frequency component of the difference current output S _2x by the photocurrent sensor. Show.

Fig. 7 (m) shows the case where an internal fault occurs in the system shown in Fig. 2 and the fault current is a sinusoidal AC signal expressed by equation (3). The optical signal P _2x from sensor 2 is shown in Fig. 7 (n), the differential current output S _2x by the photo current sensor is shown in Fig. 7 (o), and the effective value of the power supply frequency component of the differential current output S _2x by the photo current sensor Is shown in Fig. 7 (p).

As shown in Fig. 7 (1) and Fig. 7 (p), the conventional technology A crop is obtained.

As described above, in the conventional technology, if the fault current is superimposed on the DC component, it is detected normally in the case of an internal fault, but as if an internal fault occurred in the case of an external fault. An error signal may be generated.

An object of the present invention is to detect a fault current superimposed with a direct current component, not only when an internal fault occurs, but also when an external fault occurs, without discriminating that the fault is an internal fault. An object of the present invention is to propose a protection relay device using a photocurrent sensor that does not perform unnecessary operations.

Disclosure of the invention

Therefore, the present invention provides two first and second photocurrent sensors that individually measure input and output currents at both ends of a protection section of a power system, wherein the first photocurrent sensor has an incident end, The analyzer has an analyzer that performs analysis in two polarization directions of plus 45 degrees and a minus 45 degrees with respect to the polarization direction of the polarizer provided at the incident end, and an emission end for each of the analysis components. Optical fiber transmission between the light source and the first photocurrent sensor, between the first and second photocurrent sensors, and between the second photocurrent sensor and the optical signal processing unit. A difference current detection unit that detects a difference current component from an output signal of the optical signal processing unit; a sum current detection unit that detects a sum current component from an output signal of the optical signal processing unit; and a difference current detection unit. An operation amount calculating means for obtaining an operation amount from an output; A suppression amount calculating means for obtaining a suppression amount from an output of the output means and an output of the sum current detecting means; A protection relay device using a photocurrent sensor, comprising: a determination unit configured to determine whether an accident is within the protection section or outside the protection section of the power system from the output of the operation amount calculation unit and the output of the operation ratio calculation unit. It is provided.

In addition, the present invention provides two first and second photocurrent sensors that individually measure input and output currents at both ends of a protection section of a power system, wherein the first photocurrent sensor has an incident end and It has an analyzer that performs analysis in two polarization directions of plus 45 degrees and minus 45 degrees with respect to the polarization direction of the polarizer provided at the incident end, and an emission end for each of the analysis components. Between the light source and the first photocurrent sensor, the first and second Differential current detecting means for connecting optical current sensors to each other and between the second photocurrent sensor and the optical signal processing unit by optical fiber transmission, and detecting a differential current component from an output signal of the optical signal processing unit. Sum current detection means for detecting a sum current component from the output signal of the optical signal processing unit; and correction calculation means for obtaining individual input / output currents from the output of the difference current detection means and the output of the sum current detection means. An operation amount calculating means for obtaining an operation amount from the correction operation means; a suppression amount calculating means for obtaining a suppression amount from the correction operation means; an operation from an output of the operation amount calculating means and an output of the suppression amount calculating means. Operating ratio calculating means for obtaining a ratio, and determining means for judging whether the accident is within the protection section or outside the protection section of the power system from the output of the operation amount calculation means and the output of the operation ratio calculation means. Equipped photoelectric A protection relay device using a flow sensor is provided. Further, the present invention is a protection relay device for monitoring an accident of a power system having a protection section, wherein the protection relay device includes:

A light source for emitting a predetermined optical signal,

A first photocurrent sensor disposed on one end side of the protection section of the power system, the first photocurrent sensor receiving the optical signal from the light source, Rotating the polarization plane of the optical signal in proportion to the magnitude of the first current flowing on one end side, and converting the first optical signal of at least one direction component of the optical signal whose polarization plane has been rotated. A first photocurrent sensor that emits;

A second photocurrent sensor disposed at the other end of the protection section of the power system, wherein the second photocurrent sensor transmits the first optical signal from the first photocurrent sensor. Receiving the first optical signal, further rotating the polarization plane of the first optical signal in proportion to the magnitude of the second current flowing to the other end of the protection section of the power system, and further rotating the polarization plane. A second photocurrent sensor that emits a second optical signal of one direction component and a third optical signal of another direction component of the first optical signal;

A first optical signal processing unit for obtaining a difference current output that is a difference between the first current and the second current from the second optical signal;

A second optical signal processing unit for obtaining a sum current output that is a sum of the first current and the second current from the third optical signal; A difference current detection unit that detects the difference current output of the first optical signal processing unit; a sum current detection unit that detects the sum current output of the second optical signal processing unit; and An operation amount calculating means for obtaining an operation amount from the output;

Suppression amount calculation means for obtaining the suppression amount from the output of the difference current detection means and the output of the sum current detection means,

An operation ratio calculating unit that obtains an operation ratio from the output of the operation amount calculating unit and the output of the suppression amount calculating unit;

A protection means comprising: a determination means for determining whether the power gun has an accident inside the protection section or outside the protection section based on an output of the operation amount calculation means and an output of the operation ratio calculation means. An electric device is provided.

Further, the present invention is a protection relay device for monitoring an accident of a power system having a protection section, wherein the protection relay device includes:

A light source for emitting a predetermined optical signal,

A second optical signal processing unit for obtaining a sum current output that is a sum of the first current and the second current from the third optical signal;

Difference current detection means for detecting the difference current output of the first optical signal processing unit, Sum current detection means for detecting the sum current output of the second optical signal processing unit, and correction calculation means for obtaining individual input / output currents from the output of the difference current detection means and the output of the sum current detection means When,

Operation amount calculation means for obtaining an operation amount from an output of the correction operation means,

Suppression amount calculation means for obtaining the suppression amount from the output of the correction calculation means,

A protection relay device comprising: a determination unit that determines whether an accident is inside the protection section of the power system gun or outside the protection section based on an output of the operation amount calculation unit and an output of the operation ratio calculation unit. To provide.

The present invention also provides a method for detecting an accident in a power system having a protected section,

Arranging a first photocurrent sensor at one end of the protection section of the power system;

By the first photocurrent sensor, sensing a magnitude of a first current flowing on one end side of the protection section of the power system;

Placing a second photocurrent sensor at the other end of the protection section of the power system;

Sensing the magnitude of a second current flowing on the other end side of the protection section of the power system by the second photocurrent sensor;

Obtaining a difference current output which is a difference between the first current and the second current; obtaining a sum current output which is a sum of the first current and the second current; and Obtaining a motion amount from

Determining a suppression amount from the difference current output and the sum current output; and determining an operation ratio from the operation amount and the suppression amount;

Detecting an accident inside the protection section of the electric power system or outside the protection section based on the operation amount and the operation ratio output. It provides a way to get out.

Further, the present invention is a method for detecting an accident in a power system having a protection zone,

A step for obtaining a difference current output that is a difference between the first current and the second current; a step for obtaining a sum current output that is a sum of the first current and the second current; and the difference current output Calculating an individual input / output current from the sum current output; andcalculating an operation amount from the input / output current;

Obtaining a suppression amount from the input / output current;

Obtaining an operation ratio from the operation amount and the suppression amount;

Determining whether the accident is inside the protection section of the power system or outside the protection section based on the operation amount and the operation ratio. Is what you do. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a configuration diagram illustrating an embodiment according to the present invention and illustrating a protection relay device using a photocurrent sensor.

FIG. 2 is a system diagram illustrating an embodiment according to the present invention and illustrating a protection relay device using a photocurrent sensor. FIG. 3 is an example of an output waveform when fault current is measured according to the embodiment of the present invention.

FIG. 4 is a configuration diagram illustrating another embodiment according to the present invention and illustrating a protection relay device using a photocurrent sensor.

FIG. 5 is an example of an output waveform when a fault current is measured according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram of a protection relay device using a conventional photocurrent sensor. FIG. 7 is an example of an output waveform when a fault current is measured according to a conventional technique. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

The prior art (5 a), (5 b ) As indicated formula, the output signal from the optical current sensors is x, the light P _{2 x} 2 component in the y-direction, there are P _{2 y,} conventional The technology uses only one or the other. By using the optical signal that is not used, even if an external accident where DC components are superimposed occurs, it is not erroneously determined that the accident is an internal accident, that is, it is possible to determine whether the accident is an external accident or an internal accident. The possibilities are explained below.

FIG. 1 is an explanatory diagram showing an embodiment of a protective relay device using the photocurrent sensor of the present invention. Using optical signal P _{2 y} signal in the same way as using the optical signal P _{2 x} to determine a difference current signal S _{2 x} by the optical current sensor.

The differential current signal S _{2 x} by the photocurrent sensor obtained from the optical signal P _{2 x} is the difference between the current ii detected by the first photocurrent sensor 1 S and the current i ₂ detected by the second photocurrent sensor 2. while has information of ii + i ₂ which is a flow, the optical signal P ₂ from _y i丄and i is the _second sum current II- i ₂ sum has information current output S _The fact that _{2 y} can be obtained will be described below. Incidentally, the sum current of the protection section 9 of the power system i - i ₂ and indicated Runowa, the inflow direction to the protected section 9 of both power system the sign of i have i ₂ +, as one of the outflow direction By definition.

In the following description, in the figures and formulas referred to in the section of "Prior Art", the same or corresponding portions are denoted by the same reference characters and description thereof will be omitted. FIG. 1 shows a first photoelectric current sensor 1 including a polarizer 14, a Faraday element 11, and an analyzer 15, a second photoelectric current sensor 2 configured similarly to the first photoelectric current sensor 1, and a light source 12 And a first optical signal processing unit 4a comprising a photoelectric converter 16, a high-pass filter circuit 17, a low-pass filter circuit 18, and a divider 19, and a first optical signal processing unit 4a. A second optical signal processing unit 4b, an optical fiber transmission line 3a for transmitting an optical signal between the light source 12 and the first photoelectric current sensor 1, a first optical current sensor 1 and a second optical current An optical fiber transmission path 3 b for transmitting an optical signal between the sensors 2, an emission end for emitting an optical signal P _2x having difference current information among the two emission ends of the second optical current sensor 2, and a first light An optical fiber transmission line 3c for transmitting the signal processing unit 4a, and a sum current of two emission ends of the second photocurrent sensor 2. An optical fiber transmission line 3 d to transmit the optical signal processing unit 4 b exit end and a second for morphism exiting the optical signal P _2y having a broadcast, differential current output S of the first optical signal processing unit 4 a _The difference current detection means _5a for detecting _2x , the sum current output S2 from the second optical signal processing unit _4b , the difference current detection means _5b for detecting the _2y , and the operation amount from the output of the difference current detection means 5a Operation amount calculating means 6a for obtaining the suppression amount, the suppression amount calculating means 6b for obtaining the suppression amount from the outputs of the difference current detecting means 5a and the sum current detecting means 5b, the operation amount calculating means 6a and the suppression amount calculating means. Operation ratio calculation means 7 for obtaining the operation ratio from 6 b, and operation amount detection means 6a and the output of the operation ratio calculation means 7 and the output of the operation ratio calculation means 7 determine whether the accident is within the protection section of the power system or outside the section. It consists of means 8.

The installation status of the first photocurrent sensor 1 and the second photocurrent sensor 2 in the protection section 9 of the power system and the configuration of the optical signal processing unit 4a are the same as those of the conventional technology. The difference current output S _{2 x} by the photocurrent sensor is obtained from the unit 4a.

On the other hand, the optical signal guided by the optical fiber transmission means 3d is the _P2y signal described in equation ( _5b ). Another optical signal P _{2 y} from the second photocurrent sensor 2 is guided to the optical fiber transmission line 3 d and is incident on the photoelectric converter 16 of the second optical signal processing unit 4 b. By the same signal processing, the sum current output _S2y by the photocurrent sensor is obtained. The sum current output S _2y by the photocurrent sensor is expressed by the following equation.

S _2y = (AC component of P _2y ) / (DC component of P _2y ) _{··························································································} (17) And S in equation (6) _2X and S _{2y in the} expression (17) can be simply expressed as follows.

S _2x = « ₀ (i i + i ₂ ) + δ _χ (1 8 a)

S _2y = « ₀ (i i-i ₂ ) + δ _γ (1 8 b) where Q !. = 2V, where V is the Verdet constant of the photocurrent sensor.

Here, the error signal component [delta] _x contained in (1 8 a) expression of the difference current component paragraph is included in the S _2x signal, the second term S ₂ _x signal.

Similarly, the error signal component [delta] _gamma where (1 8 b) paragraph S _2y sum current component included in the signal type, the second term included in the S ₂ _y signal.

δ _、, <5 _y is due to the transiently attenuated signal on which the DC component is superimposed, and occurs until the DC component is attenuated as expressed by equation (16).

In general, the operating ratio k of the differential relay, which is used as a protection relay, is expressed by the following equation as the ratio of the operation amount m to the suppression amount n.

Movement ratio k = m / n · ·--(1 9) Movement amount m = I ii + i ₂ I · · · (20 a) Suppression amount n = I i I + I i ₂ I • • • ■ ( 20 b) where I ii + i ₂ I represents the effective value of the difference current i 丄 + i ₂ , I i I and I i ₂ I represent the respective effective values and the effective value of i ₂ .

(18a) Equation (18b) includes error signals < _5x , _dy, but assuming that the magnitude is negligible, _S2x and _S2x obtained by the difference current detection means _5a The method of calculating the operating ratio k expressed by Eq. (19) using _S2y obtained by the sum current detection means _5b is shown below.

The motion amount m in equation (20a) is obtained by the motion amount calculation means 6a in FIG. 1 as in equation (21a).

= a ₀ (i ₁ + ί ₂ )

m = I i i + i ₂ I-IS _2x I / a ₀ '''' (2 1 a)

The suppression amount n in the expression (20b) is obtained by the suppression amount calculating means 6 as shown in the expression (21b).

(i! + i ₂ ) + δ _χ + « ₀ (ii— i ₂ ) + <5 _y = 2 _n -i-, + δ '

2 α _n

(S 2x + S 2, _v y) (2 a J

S 2 x ° 2 y− 0 (i + i J + δ- _a () -δ = 2 a + δ

2 a _n

I i 2 (° 2 x ^_ ° 2?. Vy) (2 a _n )

n = I i 1 I + ¹ i 2

= {(S _2x + S 2y) I + I (S _? -S _2v ) I} / (2 Q ' ₀ )

• (2 1 b)

The operation ratio k is obtained by substituting the expressions (21a) and (21b) into the expression (19) in the operation ratio calculating means 7.

= m / n ~ I i ₁ + i + I)

= il S la (S _2x + S 2y) + (s 2 x S _2y ) 1 / (2 a ₀ )}

= 2 S 2x (I s 2x + S 2y + I s, -s 2y) (22) The operation amount m obtained by the operation amount calculation means 6 a and the operation ratio k obtained by the operation ratio detection operation 7 are: In the judgment means 8, when the operation amount setting value is kl and the operation ratio setting value is k2, when m> k1 and k> k2, it is judged that an internal fault has occurred. Even if it does, unnecessary actions can be prevented in the event of an external accident.

The motion amount m and the motion ratio k obtained by the above equations (21a) and (22) 'are temporarily ignored for the error components δ _χ and S _y shown in the equations (18a) and (18b). The magnitude of the error component fluctuates depending on the magnitude of the fault current and the sensitivity of the applied current sensor. However, if there is a large difference between the operation ratio k when an external accident occurs and when an internal accident occurs, the judging means 8 can determine whether the accident is inside or outside the protected area.

In the following, it is confirmed by calculation that it is possible to determine whether the accident is inside or outside the protection section by the above method in an actual power system.

The assumed maximum fault current of the power system is 33 kA, the DC component is assumed to be 100% superimposed, and the time constant is set to 10 Oms. The applied optical fiber sensor is Similar to surgery, and is lead glass fiber-type optical current sensor having a wavelength 1550 nm, the Verdet constant V is 3. 93X 10- ⁶ using [r ad / A].

In order to explain the operation of the protective relay using the photocurrent sensor of the present invention in each of the external and internal accident cases with respect to the protection section 9 of the power system, a conventional technique was used. The system diagram of Fig. 2 is used as described.

There are two types of external accidents in the system shown in Fig. 2, i.e., accident location f1 and 、 3. Since both are considered equivalent, f1 is used here as a typical example of external accidents. In the case of an internal accident, it is considered that there are three types of power supply arrangement, one at both ends, the one-sided power supply at the fl side, and the one-sided power supply at the f3 side. A single-side power supply is considered to be the same for the fl side and the f3 side, so the fl side is a representative example.

In the case of an accident in a double-sided power supply arrangement, i or i ₂ is

ii (t) = i ₂ (t)

Shall be considered.

In the case of an accident in a single-ended power supply arrangement,

i ₂ (t) = 0

And

Figure 3 is a diagram for explaining that the operating ratio k obtained from Eq. (22) has a sufficiently large difference between an internal fault and an external fault.The fault current value and the optical fiber constant Is substituted into the equations (14), (5a), (5b), (6), (17), (21a), (21b), and (22), and calculated.

As means for calculating the effective values IS _2x I, IS _2x + S _2y I and IS _2x — S _2y I of the power supply frequency components in the operation amount calculating means 6a and the suppression amount calculating means _6b, as in the prior art, The algorithm was used.

Electrical angle 30 degrees

Digital filter: DF _lf = ( _1-1 Z- ⁶ ) (l + Z ^ + Z-s + Z- ³ )

'n-3 C, n ^ n --- _f 6

Figure 3 (a) shows the fault current i (t) on which the DC component expressed by Eq. (14) is superimposed, and shows the waveform of fault current i 33 kA. Figures 3 (b) to 3 (d) show the case of an external accident, Figure 3 (b) shows the amount of operation m, Figure 3 (c) shows the amount of suppression n, and Figure 3 (d) The respective operating ratios k are shown. The fault current shows four types: i = 33 kA, 24 kA, 15 kA, and 9 kA.

Similarly, Fig. 3 (e) to Fig. 3 (g) show the case of a power supply arrangement on both sides of the internal fault.Fig. 3 (e) shows the operation amount m, and Fig. 3 (f) shows the suppression amount n. Indicates the operation ratio k. The fault current shows the following four types.

= +16.5 kA, i 2 = +16.5 kA,

= +12.0 kA, i ₂ = +12.0 kA,

i! = +7.5 kA, i ₂ = +7.5 kA,

i! = +4.5 kA, i ₂ = +4.5 kA

Figures 3 (h) to 3 (j) show the case of a single-sided internal power supply arrangement.Figure 3 (h) shows the amount of operation m, Figure 3 (i) shows the amount of suppression n, and Figure 3 (j) shows the amount of operation. Each shows the ratio k. The fault current shows four types: i ₁ = 33 kA, 24 kA, 15 kA, and 9 kA. Compare Fig. 3 (d), which shows the operating ratio k of the external accident case, with Figs. 3 (g) and 3 (j), which show the operating ratio k in each case of the internal accident power supply arrangement and the internal accident single-side power supply arrangement. As can be seen, the operating ratio k is 100% for both the single-ended power supply and the double-ended power supply in the case of an internal accident, but temporarily increased to more than 20% in the case of an external accident. Then it is obviously a small value.

Therefore, in order to determine the operation ratio setting value k2, by setting a value larger than the value of the operation ratio k that temporarily increases in an external accident, the operation amount m is determined by the determination means 8 to be smaller than the operation amount setting value k1. Even if it is large, if the operation ratio k is smaller than the operation ratio set value k2, it is determined that an external accident has occurred, and unnecessary operation of the protective relay can be prevented.

FIG. 4 is an explanatory diagram showing another embodiment of the protection relay device using the photocurrent sensor of the present invention. In the following description, in the drawings and formulas referred to in the related art and the embodiment, the same or corresponding portions are denoted by the same reference characters and description thereof is omitted.

First photocurrent sensor 1, second photocurrent sensor 2, light source 12, optical signal processing circuit 4a, optical fiber transmission means 3a, 3b, 3c, 3d, first optical signal processing unit 4a, Second optical signal processing unit 4b, difference current detection means 5a, sum current detection means 5b, difference current detection Correction operation means 5c for obtaining an individual input / output current from the output of the output means 5a and the output from the sum current detection means 5b, an operation amount calculation means 6c for obtaining the operation amount from the output of the correction operation means 5c, Suppression amount calculation means 6 d for obtaining the suppression amount from the output of the correction calculation means 5 c, operation ratio calculation means 7 for obtaining the operation ratio from the output of the operation amount calculation means 6 c and the output of the suppression amount calculation means 6 d, operation amount It comprises a judgment means 8 for judging from the output of the detection means 6 c and the output of the operation ratio calculation means 7 whether the accident is within the protection section of the power system or outside the section.

Here, equations (5a) and (5b) are rewritten as follows using approximation of equation (7).

Ρ _2Χ- (1/4) Ρ ₀ (1 + α ₀ ii) (1 + ₀ ) '

P _2y = (l / 4) P. (1 + α ₀ ii) (1_h. I ₂ ). ·. '(25 b)

(α. = 2 V)

At this time, the output S ^ from the difference current detecting means 5a and the output from the sum current detecting means 5b

S _{2 y} is expressed as follows.

S _{2 x} = «o (i 1+ ₂ ) +« o ² (ii · i ₂ ) · · (26 a)

S _{2 y} = «o (ii— i 2)-« o ² (ii * i ₂ ).. (26 b)

Here, the error current component of paragraph (26 a) formula is contained in S _2x signal, the error signal component monument second term is included in the S ₂ _x signal. ² (ii · i ₂ ). Similarly, the first term of equation ( _26b ) is the sum current component included in the _S2y signal, and the second term is the error signal component included in the _S2y signal.

Next, the output S _2x from the difference current detecting means 5 a and the output S _{2 y} from the sum current detecting means 5 b are corrected by the correction calculating means 5 c as follows. ² (i · i ₂ ) is removed. That is, as shown in the (2 7 a) (27 c ), S zl, the S _{_z 2,} S _z ₃ define, (28 a), obtaining the i have i ₂ as (28 b) expression.

° z 1−, 2x + 2y)

= Q! ₀ i! • • • • (2 7 a)

° z 2 ~ ( ⁰ 2 x S _? 2 _v y) / 2

a _n i ₉ + a 0 (

CK _n ί, 1 + 0! I,) (27 b)

= ₀ i ₂

i 1 = S _Z no a ₀ '■'-(28 a)

i 2 = S _z3 / a ₀

= S _z2 / {a ₀ (1 + S _zl )} '·''(28b)

Using i or i ₂ obtained by the correction operation means 5 c, the operation amount operation means 6 c and the suppression amount operation means 6 d use the following equations (29a) and (29 b) to calculate the operation amount m and the suppression amount. n is required.

.Moving amount m = I i! + I ₂ I

= IS _zl + S _z3 I «o · · · · (29 a)

Suppression n = ii! I + I i ₂ I

-(IS _zl I + IS _z3 I) / a,

The motion amount m obtained by the following equations (29a) and (29b) in the motion amount calculating means 6c and the suppression amount calculating means 6d, and the suppression amount n are calculated by The motion ratio k is determined.

Operating ratio k = m / n

= IS _zl + S _z3 I / (IS _zl I + IS _z3 I)… '(30) The operation amount m obtained by the operation amount calculating means 6 c and the operation ratio k obtained by the operation ratio calculating means 7 In the determination means 8, when the operation amount setting value is kl and the operation ratio setting value is k2, when m> k1 and k> k2, it is determined that an internal fault has occurred. However, unnecessary operation can be prevented even in the event of an external accident.

FIG. 5 is a diagram for explaining that the operation ratio k obtained from Eq. (30) has a sufficiently large difference between an internal accident and an external accident. It shows the result of calculation under the same conditions as used.

Figure 5 (a) shows represented by DC component indicates the fault current i _n superimposed _(t), the fault current effective value I _n = 33 kA in waveform (14). Figures 5 (b) to 5 (d) show the cases of external accidents.Figure 5 (b) shows the amount of movement m, Figure 5 (c) shows the amount of suppression n, and Figure 5 (d) shows the amount of movement k. I have. The fault current is i _{1 =} 33 kA, 24 kA, 15 kA, Four patterns of 9 kA are shown.

Similarly, Figs. 5 (e) to 5 (g) show the case of the power supply arrangement on both sides of the internal accident.Fig. 5 (e) shows the operation amount m, and Fig. 5 (f) shows the suppression amount n. Indicates the operation ratio k. The accident current shows the following four types.

= +16.5 kA, i ₂ = +16.5 kA,

i! = + 12. OkA, i ₂ = + 12.0 kA,

i _x = +7.5 kA, i ₂ = +7.5 kA,

i, = +4.5 kA, i ₂ = +4.5 kA

Figures 5 (h) to 5 (j) show the case of a single-sided internal power supply arrangement.Figure 5 (h) shows the operation amount m, Figure 5 (i) shows the suppression amount n, and Figure 5 (j) shows the operation amount. The ratio k is shown. Fault currents are shown in four ways: i! = 33 kA, 24 kA, 15 kA, and 9 kA.

As can be seen by comparing Fig. 5 (d) for the external accident case with Figs. 5 (g) and 5 (j) for the internal accident case, the operating ratio k is the case of a single-ended power supply in the internal accident case. In the case of an external accident, the operating ratio k is occasionally increased to 5% in the case of an external accident, but it is clearly smaller than that of the internal accident. By providing an operation ratio set value k2 that is larger than the value of the operation ratio k that temporarily rises when an occurrence occurs, even if the operation amount m is larger than the operation amount set value k1 in the determination means 8, the operation ratio k is If the operation ratio setting value is smaller than k2, it is determined that an external accident has occurred, and unnecessary operation of the protective relay can be prevented. Industrial applicability

As described above, according to the protection relay device using the photocurrent sensor according to the present invention, it is possible to prevent unnecessary operation of the relay even when the external accident force S occurs.

Claims

The scope of the claims

1. Two first and second photocurrent sensors for individually measuring input / output current are arranged at both ends of the protection section of the power system, wherein the first and second photocurrent sensors are an incident end, and It has an analyzer that performs analysis in two polarization directions of plus 45 degrees and minus 45 degrees with respect to the polarization direction of the polarizer provided at the entrance end, and an exit end for each of the analysis components. And an optical fiber transmission path between the light source and the first photocurrent sensor, between the first and second photocurrent sensors, and between the second photocurrent sensor and the optical signal processing unit. Connected, a difference current detection means for detecting a difference current component from the output signal of the optical signal processing unit, a sum current detection means for detecting a sum current component from the output signal of the optical signal processing unit, and the difference current An operation amount calculating means for obtaining an operation amount from an output of the detecting means; A suppression amount calculation means for obtaining a suppression amount from an output of the means and an output of the sum current detection means; an operation ratio calculation means for obtaining an operation ratio from an output of the operation amount calculation means and an output of the suppression amount calculation means; A protection relay device using a photocurrent sensor, comprising: a determination unit configured to determine whether an accident is within the protection section or outside the protection section of the power system from the output of the operation amount calculation unit and the output of the operation ratio calculation unit. .

2. Two first and second photocurrent sensors for individually measuring input / output current are arranged at both ends of the protection section of the power system, wherein the first and second photocurrent sensors are an incident end, It has an analyzer that performs analysis in two polarization directions of plus 45 degrees and minus 45 degrees with respect to the polarization direction of the polarizer provided at the entrance end, and an exit end for each of the analysis components. And an optical fiber transmission path between the light source and the first photocurrent sensor, between the first and second photocurrent sensors, and between the second photocurrent sensor and the optical signal processing unit. Connected, a difference current detection means for detecting a difference current component from the output signal of the optical signal processing unit, a sum current detection means for detecting a sum current component from the output signal of the optical signal processing unit, and the difference current From the output of the detecting means and the output of the sum current detecting means, an individual input / output current is calculated. Correction operation means for obtaining an operation amount from an output of the correction operation means; an operation amount operation means for obtaining a suppression amount from an output of the correction operation means; an output of the operation amount operation means; Obtain the operation ratio from the output of the suppression amount calculation means Operating ratio calculating means, and a judging means for determining from the output of the operating amount calculating means and the output of the operating ratio calculating means whether the accident is within the protection section of the power system or outside the protection section. A protective relay using a photocurrent sensor.

3. A protection relay device for monitoring an accident in a power system having a protection section, wherein the protection relay device includes:

A light source for emitting a predetermined optical signal,

A difference current detection unit that detects the difference current output of the first optical signal processing unit; a sum current detection unit that detects the sum current output of the second optical signal processing unit; and An operation amount calculating means for obtaining an operation amount from the output;

An operation ratio calculating unit that obtains an operation ratio from the output of the operation amount calculating unit and the output of the suppression amount calculating unit; A protection means comprising: a determination means for determining whether the power gun has an accident inside the protection section or outside the protection section based on an output of the operation amount calculation means and an output of the operation ratio calculation means. Electrical equipment.

4. In the protective relay device according to claim 3,

The first photocurrent sensor,

A first polarizer for converting a predetermined optical signal from the light source into a linearly polarized signal, and receiving the linearly polarized signal output from the first polarizer, and A first Faraday element that rotates the plane of polarization of the linearly polarized signal by a predetermined angle in proportion to the magnitude of the first current by a Faraday effect due to the generated magnetic field;

A first analyzer that divides the signal of the linearly polarized light output from the first Faraday element into at least an optical signal of a component in the X direction and an optical signal of a component in the y direction; The protective relay device, wherein the optical signal is the first optical signal.

5. The protective relay according to claim 4,

The second photocurrent sensor is

A second polarizer for converting the first optical signal from the first analyzer into a linearly polarized signal,

The linearly polarized signal output from the second polarizer is received, and the Faraday effect caused by a magnetic field generated by the second current causes the second current to be proportional to the magnitude of the second current. A second Faraday element for rotating the plane of polarization of the linearly polarized signal output from the second polarizer by a predetermined angle,

A second analyzer that divides the linearly polarized signal output from the second Faraday element into the X-direction component second optical signal and the y-direction component third optical signal.

6. The protective relay according to claim 5,

The polarization direction of the first optical signal is the same as the polarization direction of the second optical signal. Is a protective relay.

7. The protective relay according to claim 6,

The first optical signal processing unit,

A first photoelectric converter for converting the second optical signal output from the second analyzer of the second photocurrent sensor into an electric signal; and A first low-pass filter circuit for extracting a DC component from the output electric signal,

A first high-pass filter circuit for extracting an AC component from the electric signal output from the first photoelectric converter,

A protection relay device comprising: a first divider for dividing the AC component by the DC component to obtain the difference current output.

8. The protective relay according to claim 7,

The second optical signal processing unit includes:

A second photoelectric converter for converting the third optical signal output from the second analyzer of the second photocurrent sensor into an electric signal;

A second single-pass filter circuit for extracting a DC component from the electric signal output from the second photoelectric converter,

A second high-pass filter circuit for extracting an AC component from the electric signal output from the second photoelectric converter,

A protective relay device comprising: a second divider for dividing the AC component by the DC component to obtain the sum current output.

9. The protective relay according to claim 8,

The flow direction of the first current from outside the protection section to inside the protection section is positive,

The outflow direction of the first current from the inside of the protection section to the outside of the protection section is negative, The flow direction of the second current from the outside of the protection section to the inside of the protection section is positive,

A protection relay device in which the outflow direction of the second current from the inside of the protection section to the outside of the protection section is negative.

10. The protective relay according to claim 9,

The direction of propagation of light in the first photocurrent sensor is provided so as to coincide with the direction of a magnetic field generated by the first current detected by the first photocurrent sensor, and the second photocurrent is A protective relay provided so that the light propagation direction in the sensor matches the magnetic field generated by the second current detected by the second photocurrent sensor.

11. The protective relay according to claim 10,

The first analyzer is installed at an angle of 45 ° with respect to the first polarizer.

1 2. In the protective relay device according to claim 11,

The protective relay device, wherein the second analyzer is installed at an angle of 45 ° with respect to the second polarizer.

13. A protective relay device for monitoring an accident in a power system having a protected section, wherein the protective relay device includes:

A light source for emitting a predetermined optical signal,

A first photocurrent sensor disposed on one end side of the protection section of the power system, the first photocurrent sensor receiving the optical signal from the light source, Rotating the polarization plane of the optical signal in proportion to the magnitude of the first current flowing on one end side, and converting the first optical signal of at least one direction component of the optical signal whose polarization plane has been rotated. A first photocurrent sensor that emits; A second photocurrent sensor disposed at the other end of the protection section of the power system, wherein the second photocurrent sensor transmits the first optical signal from the first photocurrent sensor. Receiving, furthermore, rotating the polarization plane of the first optical signal further in proportion to the magnitude of the second current flowing to the other end of the protection section of the power system, and further rotating the polarization plane. A second photocurrent sensor that emits a second optical signal of one direction component and a third optical signal of another direction component of the first optical signal;

A difference current detection unit that detects the difference current output of the first optical signal processing unit; a sum current detection unit that detects the sum current output of the second optical signal processing unit; and Correction operation means for obtaining individual input / output currents from the output and the output of the sum current detection means;

Determining means for determining whether the accident is inside the protection zone of the power system gun or outside the protection zone based on the output of the operation amount calculation unit and the output of the operation ratio calculation unit.

1 4. A method for detecting an accident in a power system having a protection section, comprising: arranging a first photocurrent sensor on one end side of the protection section of the power system;

Arranging a second photocurrent sensor at the other end of the protection section of the power system; Sensing the magnitude of a second current flowing to the other end of the protection section of the power system by the second photocurrent sensor;

Obtaining a suppression amount from the difference current output and the sum current output; and obtaining an operation ratio from the operation amount and the suppression amount.

A method for detecting an accident in a power system, comprising: a step of determining whether the accident is inside the protection section or outside the protection section of the power system based on the operation amount and the operation ratio output.

15. A method for detecting an accident in a power system having a protection section, comprising: arranging a first photocurrent sensor at one end of the protection section of the power system;

Arranging a second photocurrent sensor at the other end of the protection section of the power system;

Obtaining a difference current output that is a difference between the first current and the second current; and obtaining a sum current output that is a sum of the first current and the second current. Calculate individual input / output current from sum current output Calculate operation amount from the input / output current Obtain the suppression amount from the input / output current.

Determining whether the accident is inside the protection section of the power system or outside the protection section based on the operation amount and the operation ratio.