JP2009033819A - Overcurrent relay device with voltage suppression - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an overcurrent relay device with voltage suppression, for preventing power failure from spreading, even two overcurrent relays with voltage suppression are installed. <P>SOLUTION: Among first-third current transformers 3<SB>1</SB>-3<SB>3</SB>, the first and second current transformers 3<SB>1</SB>and 3<SB>2</SB>are sum-connected and the second and third current transformers 3<SB>2</SB>and 3<SB>3</SB>are sum-connected. Upon detecting short-circuit failure on the basis of a first short-circuit current I<SB>Ry1</SB>to be inputted from the first and second current transformers 3<SB>1</SB>and 3<SB>2</SB>sum-connected, an interline voltage V<SB>TR</SB>and an R-phase voltage V<SB>R</SB>, a first overcurrent relay 50<SB>1</SB>with voltage suppression integrally interrupts first-third breakers 2<SB>1</SB>-2<SB>3</SB>provided on each of phases of a power transmission line. Upon detecting short-circuit failure on the basis of a second short-circuit current I<SB>Ry2</SB>to be inputted from the second and third current transformers 3<SB>2</SB>and 3<SB>3</SB>sum-connected, the interline voltage V<SB>TR</SB>and the R-phase voltage V<SB>R</SB>, a second overcurrent relay 50<SB>2</SB>with voltage suppression integrally interrupts the first-third breakers 2<SB>1</SB>-2<SB>3</SB>provided on each of phases of the power transmission line. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an overcurrent relay device with voltage suppression, and more particularly to an overcurrent relay device with voltage suppression for protecting a three-phase AC circuit from a short circuit accident.

  Conventionally, in a three-phase AC circuit, an overcurrent relay (OC) is installed for each phase in order to protect the three-phase AC circuit from a short circuit accident (see, for example, Patent Document 1 below).

  Moreover, if the detection of a short-circuit accident is performed only with the current value, the load current and the short-circuit current may not be distinguished. Therefore, the overcurrent relay with voltage suppression has a function of correcting the current detection sensitivity according to the voltage value. Is used.

For example, as shown in FIG. 10, the _first to _third current transformers (CT) 3 ₁ to ₃ 3 installed in the R-phase, S-phase, and T-phase of the transmission / distribution line respectively. Overcurrent relays with voltage suppression (OCV) 4 ₁ to 4 ₃ are connected to each other, and from the transformer for instrument 6 installed on the bus, the first overcurrent relay with voltage suppression 4 ₁ has an R phase-S phase. of the line enter the voltage V _RS, the ₂ second overcurrent relay with voltage suppression 4 enter the line voltage V _ST of S phase -T phase, the third voltage suppression with overcurrent relay 4 ₃ inputs the line voltage V _TR of the T-phase -R phase, when the short circuit occurs in the electric transmission, the first to third biasing voltage suppression overcurrent relay 41 _{to 3} in accordance with the accident appearance operates as follows, R-phase of the transmission and distribution lines, collectively blocking the first to third circuit breaker 2 ₁ to 2 ₃ of which are respectively installed on the S-phase and T-phase It has to.
(1) In the case of a short-circuit accident between the R phase and the S phase A short circuit current flows in the R phase and the S phase of the transmission and distribution line, and the line voltage V _RS between the R phase and the S phase and the line voltage V between the S phase and the T phase. _{Since ST} occurs, the first and second overcurrent relays 4 ₁ , 4 ₂ with voltage suppression operate to collectively cut off the _first to _third circuit breakers 2 ₁ to 2 ₃ .
(2) In the case of a short circuit accident between the S phase and the T phase A short circuit current flows in the S phase and T phase of the transmission and distribution line, and the S phase-T phase line voltage V _ST and the T phase-R phase line voltage V _{Since TR} occurs, the second and third overcurrent relays with voltage suppression 4 ₂ and 4 ₃ operate to collectively cut off the _first to _third circuit breakers 2 ₁ to 2 ₃ .
(3) Short-circuit accident between T-phase and R-phase Short-circuit current flows in the R-phase and T-phase of the transmission and distribution line, and the R-S phase line voltage V _RS and the T-phase-R phase line voltage V _{Since TR} occurs, the first and third overcurrent relays 4 ₁ , 4 ₃ with voltage suppression operate to collectively cut off the _first to _third circuit breakers 2 ₁ to 2 ₃ .
(4) In the case of a short circuit accident between R phase, S phase and T phase Short circuit current flows in R phase, S phase and T phase, line voltage V _RS between R phase and S phase, and line between S phase and T phase Since the voltage V _ST and the T-phase to R-phase line voltage V _TR are generated, the _first to _third overcurrent relays 4 ₁ to 4 ₃ with voltage suppression operate and the _first to _third circuit breakers 2 ₁ collectively shut off to 2 _3.

Moreover, in the power transmission / distribution line of the terminal circuit, etc., the short circuit current flows in two phases, and the overcurrent relay with voltage suppression is installed only in the two phases to reduce the equipment cost. For example, as shown in FIG. 11, the first and second current transformers 3 ₁ and 3 ₂ respectively installed in the R phase and the T phase among the R phase, S phase, and T phase of the transmission and distribution lines And the second overcurrent relay with voltage suppression 4 ₁ , 4 ₂ are connected to each other, and from the transformer 6 for the instrument installed on the bus, the first overcurrent relay with voltage suppression 4 ₁ is connected to the R-phase-S. enter the line voltage V _RS phases, the ₂ second overcurrent relay with voltage suppression 4 to input line voltage V _TR of the T-phase -R phase, when the short circuit occurs in the electric transmission The first and second voltage suppression overcurrent relays 4 ₁ , 4 ₂ operate as follows according to the accident situation, and are installed in the R phase, S phase and T phase of the transmission and distribution lines, respectively. The first to third circuit breakers 2 ₁ to 2 ₃ are collectively cut off.
(1) In the case of a short circuit accident between the R phase and the S phase Since a short circuit current flows in the R phase of the transmission and distribution line and a line voltage V _RS between the R phase and the S phase is generated, the first overcurrent relay with voltage suppression 4 ₁ operates to collectively shut off the _first to _third circuit breakers 2 ₁ to 2 ₃ .
(2) In the case of a short circuit accident between the S phase and the T phase Since a short circuit current flows in the T phase of the transmission and distribution line and a line voltage V _TR between the T phase and the R phase is generated, the second overcurrent relay with voltage suppression 4 ₂ operates to collectively shut off the _first to _third circuit breakers 2 ₁ to 2 ₃ .
(3) Short-circuit accident between T-phase and R-phase Short-circuit current flows in the R-phase and T-phase of the transmission and distribution line, and the R-S phase line voltage V _RS and the T-phase-R phase line voltage V _{Since TR} occurs, the first and second overcurrent relays with voltage suppression 4 ₁ and 4 ₂ operate to collectively cut off the _first to _third circuit breakers 2 ₁ to 2 ₃ .
(4) In the case of a short circuit accident between the R phase, the S phase, and the T phase A short circuit current flows in the R phase and the T phase, and the line voltage V _RS between the R phase and the S phase and the line voltage V _TR between the T phase and the R phase. Therefore, the first and second overcurrent relays with voltage suppression 4 ₁ , 4 ₂ operate to collectively cut off the _first to _third circuit breakers 2 ₁ to 2 ₃ .
JP-A-8-005659

However, since two or three overcurrent relays with voltage suppression are installed for each transmission / distribution line, there are the following problems.
(1) There is a request to reduce the equipment cost by setting the number of overcurrent relays with voltage suppression to two instead of three.
(2) If the number of overcurrent relays with voltage suppression is two, it is possible to protect the three-phase AC circuit from a short circuit accident of its own circuit, but an overcurrent relay with voltage suppression is installed. Short circuit accidents that do not extend to other phases and other circuits cannot be detected, and the three-phase AC circuit is protected by the short-circuit protection relay on the power supply side, thus expanding the range of power outages.

  An object of the present invention is to provide an overcurrent relay device with voltage suppression that can prevent the expansion of the power outage range even when the number of overcurrent relays with voltage suppression is set to two.

The overcurrent relay device with voltage suppression of the present invention is an overcurrent relay device with voltage suppression for protecting a three-phase AC circuit from a short-circuit accident, and is installed in a first phase of the three-phase AC circuit. The first current transformer (3 ₁ ) and the second current transformer (3) installed in the second phase of the three-phase AC circuit and connected to the first current transformer. ₂ ) and a third current transformer (3 ₃ ) installed in the third phase of the three-phase AC circuit and connected to the second current transformer. When a short circuit fault is detected based on the first short circuit current (I _Ry1 ) input from the first and second current transformers and the voltage information of the three phase AC circuit, each phase of the three phase AC circuit is detected. the first to third circuit breaker installed and (2 ₁ to 2 ₃₎ the first voltage suppression with overcurrent relay for collectively blocking (50 _1), second and third variable which is the sum connected Upon detection of a short circuit on the basis of a second short-circuit current which is inputted from the vessel and (I _Ry2) to said voltage information, it said first to third second overcurrent relay with voltage suppression for collectively blocking the circuit breaker (50 ₂ ).
Here, the first and second voltage suppression overcurrent relays use one line voltage (V _TR ) and one phase voltage (V _R ) in a predetermined combination obtained from the voltage information, When the line voltage is equal to or lower than the predetermined first voltage value (k1), it is determined that a short-circuit accident has occurred, and the predetermined second voltage value is greater than the first voltage value. A short-circuit accident occurs when the phase of the line voltage is delayed or advanced by a predetermined angle range (α) with respect to the phase of the line voltage before the short-circuit accident as a reference. May be determined.
The first and second overcurrent relays with voltage suppression are configured such that the line voltage is less than or equal to the second voltage value and the line voltage is based on a phase of the line voltage before a short circuit accident. When the phase is delayed only within the angular range, it is determined that there is a short-circuit accident between the first phase and the second phase of the three-phase AC circuit, and the line voltage is the second voltage. And when the phase of the line voltage advances only within the angle range with reference to the phase of the line voltage before the short-circuit accident, the second phase of the three-phase AC circuit It is determined that there is a short circuit accident with the third phase, the line voltage is equal to or less than the first voltage value, and the line voltage is based on the phase of the line voltage before the short circuit accident. The phase of the phase voltage is not delayed or advanced by the angle range, and the phase voltage before the short circuit accident A short-circuit accident between the first phase and the third phase of the three-phase AC circuit when the phase of the phase voltage is advanced by a predetermined other angle range (β) as a reference. The line voltage is less than or equal to the first voltage value, and the phase of the line voltage is delayed or advanced by the angle range with reference to the phase of the line voltage before the short circuit accident. The three-phase alternating current when the phase voltage phase is not delayed or advanced within the other angle range with reference to the phase voltage phase before the short-circuit accident. It may be determined that there is a short circuit accident between the first phase, the second phase, and the third phase of the circuit.
When the first and second overcurrent relays with voltage suppression determine that a short-circuit accident has occurred, a suppression voltage (V _Ry ) is calculated using the line voltage, and a current is generated according to the calculated suppression voltage. When the amplitudes of the first and second short circuit currents exceed the current set value determined by the voltage suppression characteristic that defines the set value, the first to third circuit breakers may be collectively cut off.
In the case of a short circuit accident between the first phase and the second phase of the three-phase AC circuit, only the second overcurrent relay with voltage suppression operates and the first to third In the case of a short circuit accident between the second phase and the third phase of the three-phase AC circuit, only the first overcurrent relay with voltage suppression operates. Then, the first to third circuit breakers may be collectively disconnected.

  The overcurrent relay device with voltage suppression according to the present invention connects the first and second current transformers respectively installed in the first and second phases of the three-phase AC circuit and connects the first and second current transformers. Short-circuit across the circuit and other circuits even if the number of overcurrent relays with voltage suppression is two by connecting the second and third current transformers installed in the second and third phases respectively. There is an effect that it is possible to reliably detect an accident and prevent the expansion of the power outage range.

  For the above purpose, the first and second current transformers installed in the first and second phases of the transmission / distribution line are connected together, and the second current transformer and the third of the transmission / distribution line are connected. A first short-circuit current that is input from the first and second current transformers that are sum-connected to the third current transformer that is installed in the phase. When a short circuit fault is detected based on one line voltage and one phase voltage of a predetermined combination of power transmission and distribution lines, the first to third circuit breakers installed in each phase of the transmission and distribution lines are collectively shut off In addition, the overcurrent relay with the second voltage suppression has a line voltage of a predetermined combination of the second short-circuit current and the transmission / distribution line input from the first and third current transformers connected in sum. When a short-circuit accident is detected based on one phase voltage, it is realized by collectively shutting off the first to third circuit breakers. .

Embodiments of an overcurrent relay device with voltage suppression according to the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the overcurrent relay device with voltage suppression according to one embodiment of the present invention is installed in the R phase and the S phase of the transmission and distribution lines, respectively, and the first and second connected in sum. a current transformer 3 _1, 3 _2, installed in the T-phase of the transmission and distribution lines, and a third current transformer 3 ₃ which is a second current transformer 3 ₂ and OR connection, is the sum connected The first short-circuit current I _Ry1 input from the first and second current transformers 3 ₁ and 3 ₂ and the voltage information (R-phase, S-phase and When a short circuit accident is detected on the transmission / distribution line based on the T-phase-R line voltage V _TR and the R-phase phase voltage V _R obtained from the T-phase phase voltage), the R-phase, S a phase and T-phase to the first to third circuit breaker 2 ₁ to 2 ₃ first voltage overcurrent relay 50 ₁ with suppressed for collectively blocking the installed respectively, the second and third are the sum connected Current transformers 3 _2, 3 ₃ and the second short-circuit current I _Ry2 and between T phase -R phase of the line obtained from the voltage information input from the potential transformer 6 Voltage V _TR and R-phase inputted from the When a short circuit accident is detected based on the phase voltage V _R , a second overcurrent relay with voltage suppression 50 ₂ is provided that collectively cuts off the _first to _third circuit breakers 2 ₁ to 2 ₃ .

Therefore, when the load currents flowing in the R phase, S phase, and T phase of the transmission and distribution line when no short circuit accident has occurred are represented by I _R , I _S , and I _T , as shown in FIG. Since the phase load current I _R and the S phase load current I _S flow through the first and second current transformers 3 ₁ and 3 ₂ with a phase difference of 120 °, respectively, the sum-connected first and second currents The first load current I ₁ input from the current transformers 3 ₁ and 3 ₂ to the first overcurrent relay 50 ₁ with voltage suppression is the difference between the R-phase load current I _R and the S-phase load current I _S. A vector sum is obtained, and the amplitude of the first load current I _{1 is} the amplitude of the R-phase load current I _R (the S-phase load current I _S ).
I ₁ = I _R + I _S
| I ₁ | = | I _R + I _S | = | I _R | = | I _S |
Similarly, as shown in FIG. 2A, the second and third current transformers 3 ₂ and 3 ₃ are connected with a phase difference of 120 ° between the S-phase load current I _S and the T-phase load current I _T. Since the current flows respectively, the second load current I ₂ input from the second and third current transformers 3 ₂ , 3 ₃ connected to the sum to the second overcurrent relay 50 ₂ with voltage suppression is an S-phase load. The vector sum of the current I _S and the T-phase load current I _T is obtained, and the amplitude of the _second load current I _{2 is} the amplitude of the S-phase load current I _S (T-phase load current I _T ).
I ₂ = I _S + I _T
| I ₂ | = | I _S + I _T | = | I _S | = | I _T |

Further, in the first and second overcurrent relays 50 ₁ and 50 ₂ with voltage suppression, the phase of the T-phase to R-phase line voltage V _TR is 210 ° and the phase of the R-phase voltage V _R is 0. It operates on the basis of being ° (see FIG. 2B).

For this reason, the line voltage V _RS between the R phase and the S phase at the time of the short circuit accident between the R phase and the S phase of the transmission and distribution line and the line voltage V _ST between the S phase and the T phase at the time of the short circuit accident between the S phase and the T phase. Is 85 V of short-circuit accident detection sensitivity, the first and second overcurrent relays 50 ₁ , 50 ₂ with voltage suppression have a T-phase to R-phase line voltage V _TR of a predetermined first voltage value k1 = It is determined that a short-circuit accident has occurred on the condition that it is 85 V or less, and the T-phase to R-phase line voltage V _TR is a predetermined second voltage value k2 = 104.3 V or less, and a short-circuit accident proceed whether the phase of the previous T-phase -R phase of the line voltage V _TR of the phase = 210 ° of the time short circuit as a reference T phase -R phase line voltage V _TR of delayed by a predetermined angular range α (5.95 ° ≦ α ≦ 30 ° or −30 ° ≦ α ≦ −5.95 °) The following (1) and reference (2) below).
V _TR ≦ [{(110/3 ^1/2 ) × 1.5} ² + (85/2) ² ] ^1/2
≦ (95.26 ² +42.5 ² ) ^1/2
≦ 104.3 (V) (1)
α ≧ 30 ° -tan ⁻¹ (42.5 / 95.26)
≧ 5.95 (°) (2)

Further, when the first and second overcurrent relays with voltage suppression 50 ₁ and 50 ₂ determine that a short-circuit accident has occurred, the first and second overcurrent relays 50 ₁ and 50 ₂ determine the accident aspect and the result of the determination of the accident aspect as follows. Accordingly, the suppression voltage V _Ry is calculated.

(1) In the case of a short-circuit accident between the R phase and the S phase The line voltage V _TR between the T phase and the R phase is 104.3 V or less, and the line voltage V _TR between the T phase and the R phase before the short circuit accident is When the phase of the line voltage V _TR between the T phase and the R phase is delayed by an angle range α (+ α) with reference to the phase = 210 °, the first and second overcurrent relays with voltage suppression 50 ₁ , 50 ₂ is determined as a short circuit accident between the R phase and the S phase (see FIG. 3A).
When a short circuit accident occurs between the R phase and the S phase, an R phase short circuit current I _FR flows in the R phase of the transmission / distribution line in the internal direction as shown by a broken arrow in FIG. While the short-circuit current I _FS phase flows to the outside direction, the T-phase of the transmission and distribution lines does not flow a short-circuit current I _FT T-phase.
Therefore, the first short-circuit current I _Ry1 input to the first overcurrent relay with voltage suppression 50 ₁ from the first and _second current transformers 3 ₁ and 3 ₂ connected in sum is shown by a solid line in FIG. As indicated by the thick arrow, the vector sum of the R-phase short-circuit current I _FR and the S-phase short-circuit current I _FS is obtained, and the amplitude of the first short-circuit current I _Ry1 is “0” (see FIG. 4A). In FIG. 4, the short-circuit currents I _FR , I _FS and I _FT flowing in the inner direction of the transmission / distribution line are solid arrows, and the short-circuit currents I _FR , I _FS and I _FT flowing in the outer direction of the transmission / distribution line are (Indicated by a dashed-dotted arrow).
I _Ry1 = I _FR + I _FS = 0
| I _Ry1 | = | I _FR + I _FS | = 0
Further, the second short-circuit current I _Ry2 input from the second and third current transformers 3 ₂ and 3 ₃ connected in sum to the second overcurrent relay 50 ₂ with voltage suppression is shown by a broken line in FIG. As indicated by the thick arrow, the S-phase short-circuit current I _{FS is obtained} , and the amplitude of the second short-circuit current I _{Ry2 is} the amplitude of the S-phase short-circuit current I _FS (see FIG. 4A).
I _Ry2 = I _FS
| I _Ry2 | = | I _FS |
The first and second overcurrent relays with voltage suppression 50 ₁ , 50 ₂ calculate the suppression voltage V _Ry by the following formula using the T-phase to R-phase line voltage V _TR .
V _Ry = 2 × V × cos (60 ° + α)
Here, V = V _TR ∠ (210 ° + α)
(2) In the case of a short circuit accident between the S phase and the T phase The line voltage V _TR between the T phase and the R phase is 104.3 V or less, and the line voltage V _TR between the T phase and the R phase before the short circuit accident is The first and second overcurrent relays with voltage suppression 50 ₁ when the phase of the line voltage V _TR of T phase-R phase is advanced only within the angle range α (−α) with respect to the phase = 210 °. , 50 ₂ are determined as a short-circuit accident between the S phase and the T phase (see FIG. 3B).
When a short circuit accident S phase -T phase occurs, the short-circuit current I _FS of S-phase flows inwardly into S phase of the transmission and distribution lines, as shown by the dashed thick arrows in FIG. 6, the T-phase of the transmission and distribution lines short-circuit current I _FT T-phase is flowing to the outside direction, the R-phase of the transmission and distribution lines does not flow a short-circuit current I _FR of R-phase.
Therefore, the first short-circuit current I _Ry1 input from the first and _second current transformers 3 ₁ and 3 ₂ connected in sum to the first overcurrent relay 50 ₁ with voltage suppression is shown by a solid line in FIG. As indicated by a thick arrow, the S-phase short-circuit current I _{FS is obtained} , and the amplitude of the first short-circuit current I _{Ry1 is} the amplitude of the S-phase short-circuit current I _FS (see FIG. 4B).
I _Ry1 = I _FS
| I _Ry1 | = | I _FS |
Further, the second short-circuit current I _Ry2 input to the second overcurrent relay with voltage suppression 50 ₂ from the second and third current transformers 3 ₂ and 3 ₃ connected in sum is shown by a broken line in FIG. As indicated by the thick arrow, the vector sum of the S-phase short-circuit current I _FS and the T-phase short-circuit current I _FT is obtained, and the amplitude of the second short-circuit current I _Ry2 is “0” (see FIG. 4B). .
I _Ry2 = I _FS + I _FT = 0
| I _Ry2 | = | I _FS + I _FT | = 0
The first and second overcurrent relays with voltage suppression 50 ₁ , 50 ₂ calculate the suppression voltage V _Ry by the following formula using the T-phase to R-phase line voltage V _TR .
V _Ry = 2 × V × cos (60 ° + α)
Here, V = V _TR ∠ (210 ° −α)
(3) In the case of a short circuit accident between the T phase and the R phase The line voltage V _TR between the T phase and the R phase is 85 V or less, and the phase of the line voltage V _TR between the T phase and the R phase before the short circuit accident = The phase of the line voltage V _TR between the T phase and the R phase is not delayed or advanced by an angle range α with respect to 210 ° (that is, greater than −5.95 ° and 5.95 °). And the phase of the R-phase phase voltage V _R before the short circuit accident is 0 ° as a reference, and the phase of the R-phase phase voltage V _R has a predetermined other angle range β (6.76 ° ≦ β ≦ 60 °, see equation (3)) (−β), the first and second overcurrent relays with voltage suppression 50 ₁ , 50 ₂ have a short circuit accident between the T phase and the R phase. Determination is made (see FIG. 3C).
β ≧ 60 ° -tan ⁻¹ [42.5 / {110 / (2 × 3 ^1/2 )}]
≧ 6.76 (°) (3)
When a short-circuit accident between the T-phase and the R-phase occurs, a T-phase short-circuit current I _FT flows in the T-phase of the transmission / distribution line in the internal direction as shown by the broken arrow in FIG. While the short-circuit current I _FR phase flows to the outside direction, the S-phase of the transmission and distribution lines does not flow a short-circuit current I _FS of S phase.
Therefore, the first short-circuit current I _Ry1 input to the first overcurrent relay with voltage suppression 50 ₁ from the first and _second current transformers 3 ₁ and 3 ₂ connected in sum is represented by a solid line in FIG. As indicated by the thick arrow, the R-phase short-circuit current I _{FR is obtained} , and the amplitude of the first short-circuit current I _{Ry1 is} the amplitude of the R-phase short-circuit current I _FR (see FIG. 4C).
I _Ry1 = I _FR
｜ I _Ry1 ｜ ＝ ｜ I _FR ｜
Further, the second short-circuit current I _Ry2 input to the second overcurrent relay 50 ₂ with voltage suppression from the second and third current transformers 3 ₂ and 3 ₃ connected in sum is represented by a broken line in FIG. As indicated by the thick arrow, the T-phase short-circuit current I _{FT is obtained} , and the amplitude of the second short-circuit current I _{Ry2 is} the amplitude of the T-phase short-circuit current I _FT (see FIG. 4C).
I _Ry2 = I _FT
| I _Ry2 | = | I _FT |
The first and second overcurrent relays with voltage suppression 50 ₁ , 50 ₂ calculate the suppression voltage V _Ry by the following formula using the T-phase to R-phase line voltage V _TR .
V _Ry = V
Here, V = V _TR ∠210 °
(4) In the case of a short circuit accident between R phase, S phase and T phase The line voltage V _TR between T phase and R phase is 85V or less, and the line voltage V _TR between T phase and R phase before the short circuit accident. The phase of the line voltage V _TR between the T-phase and the R-phase is not delayed or advanced by the angle range α with respect to the phase of 210 = 210 ° (that is, greater than −5.95 ° and 5 .. is smaller than .95 °), and the phase of the R phase voltage V _R before the short-circuit accident is 0 ° or the phase of the R phase voltage V _R is delayed or advanced by another angle range β. The first and second overcurrent relays with voltage suppression 50 ₁ , 50 ₂ are R on the condition that the first and second voltage suppression overcurrent relays 50 ₁ , 50 ₂ are not deviated (ie, larger than −6.76 ° and smaller than 6.76 °) It is determined as a short-circuit accident between phase S, phase S, and phase T (see FIG. 3D).
When a short circuit accident occurs between the R phase, the S phase, and the T phase, the short circuit current I _FR of the R phase to the R phase, the S phase, and the T phase of the transmission and distribution line as shown by the broken arrows in FIG. The current I _FS and the T-phase short-circuit current I _FT flow in the internal direction with a phase difference of 120 °.
Therefore, the first short-circuit current I _Ry1 input to the first overcurrent relay 50 ₁ with voltage suppression from the first and _second current transformers 3 ₁ and 3 ₂ connected in sum is represented by a solid line in FIG. As indicated by the thick arrows, the vector sum of the R-phase short-circuit current I _FR and the S-phase short-circuit current I _FS is obtained, and the amplitude of the first short-circuit current I _Ry1 is the R-phase short-circuit current I _FR (S-phase short-circuit current I _FS ) (see FIG. 4D).
I _Ry1 = I _FR + I _FS
| I _Ry1 | = | I _FR + I _FS | = | I _FR | = | I _FS |
Further, the second short-circuit current I _Ry2 input from the second and third current transformers 3 ₂ and 3 ₃ connected in sum to the second overcurrent relay 50 ₂ with voltage suppression is shown by a broken line in FIG. As indicated by the thick arrow, the vector sum of the S-phase short-circuit current I _FS and the T-phase short-circuit current I _FT is obtained, and the amplitude of the second short-circuit current I _Ry2 is the S-phase short-circuit current I _FS I _FT ) (see FIG. 4D).
I _Ry2 = I _FS + I _FT
| I _Ry2 | = | I _FS + I _FT | = | I _FS | = | I _FT |
The first and second overcurrent relays 50 ₁ and 50 ₂ with voltage suppression use the T-phase to R-phase line voltage V _TR to calculate the suppression voltage V _{Ry according} to the following equation.
V _Ry = V
Here, V = V _TR ∠210 °

The first and second overcurrent relays 50 ₁ , 50 ₂ with voltage suppression have a current set value determined by a voltage suppression characteristic (see FIG. 9) that defines the magnification of the current set value according to the suppression voltage V _Ry . when the amplitude of the first and second short-circuit current I _Ry1, I _Ry2 is exceeded, collectively blocking the first to third circuit breaker 2 ₁ to 2 _3.
In the case of a short-circuit accident between the R-phase and the S-phase, the amplitude of the first short-circuit current I _Ry1 becomes “0”, but the first to first currents are controlled by the operation of the _second overcurrent relay with voltage suppression 50 ₂ . Since the 3 circuit breakers 2 ₁ to 2 _{3 are} collectively cut off, there is no problem. In the case of a short-circuit accident between the S-phase and the T-phase, the amplitude of the second short-circuit current I _Ry2 becomes “0”, but the first to the second currents are controlled by the operation of the first overcurrent relay 50 ₁ with voltage suppression. Since the 3 circuit breakers 2 ₁ to 2 _{3 are} collectively cut off, there is no problem.

In the above description, the first and second current transformers 3 ₁ and 3 ₂ installed in the R phase and the S phase of the transmission / distribution line are connected together and installed in the S phase and the T phase of the transmission / distribution line. Although the second and third current transformers 3 ₂ and 3 ₃ are sum-connected, the _two current transformers to be sum-connected may be in other combinations.
Further, although the T-phase-R phase line voltage V _TR and the R-phase phase voltage V _R are used, any one of the voltage combinations indicated by circles in Table 1 may be used. However, it is necessary to change the short-circuit accident occurrence determination condition and the accident aspect determination condition described above according to the combination of voltages.

  In the overcurrent relay device with voltage suppression according to the present invention, when two sets of current transformers and overcurrent relays with voltage suppression are used in combination for the transmission and distribution lines, there is a short-circuit accident that spans other circuits. Since a short-circuit current flows in any phase of its own circuit, this short-circuit accident can be reliably detected by at least one of the two overcurrent relays with voltage suppression.

  In the above, the current transformer connected in combination with the overcurrent relay with voltage suppression used in the transmission / distribution line has been described. However, the current transformer connected in the sum is a three-phase AC circuit other than the transmission / distribution line. The same effect can be obtained even when combined with the overcurrent relay with voltage suppression used in the above.

It is a figure for demonstrating the overcurrent relay apparatus with a voltage suppression by one Example of this invention. First and second load currents I ₁ and I ₂ input to the first and second voltage suppression overcurrent relays 50 ₁ and 50 ₂ shown in FIG. is a diagram for explaining the phase voltage V _R of the first and second voltage suppression with overcurrent relay 50 _1, 50 between the lines of the T-phase -R phase to be input to the _second voltage V _TR and R-phase. When a short-circuit accident occurs, the T-phase-R line voltage V _TR and the R-phase phase voltage input to the first and second overcurrent relays 50 ₁ , 50 ₂ with voltage suppression shown in FIG. it is a diagram for explaining V _R. For the first and second biasing voltage suppression overcurrent relay 50 _1, 50 ₂ to the first and second input respectively of the short-circuit current I _Ry1, I _Ry2 be described as shown in FIG. 1 when a short circuit accident occurs FIG. When a short circuit accident occurs between the R-phase and the S-phase of the transmission / distribution line, the first and second input respectively to the first and second overcurrent relays 50 ₁ and 50 ₂ with voltage suppression shown in FIG. it is a diagram for explaining a short-circuit current I _Ry1, I _Ry2. When a short circuit accident occurs between the S phase and the T phase of the transmission / distribution line, the first and second input respectively to the first and second overcurrent relays 50 ₁ and 50 ₂ with voltage suppression shown in FIG. it is a diagram for explaining a short-circuit current I _Ry1, I _Ry2. When a short circuit accident occurs between the T phase and the R phase of the transmission / distribution line, the first and second input respectively to the first and second overcurrent relays 50 ₁ and 50 ₂ with voltage suppression shown in FIG. it is a diagram for explaining a short-circuit current I _Ry1, I _Ry2. The first and second overcurrent relays 50 ₁ and 50 ₂ with voltage suppression shown in FIG. 1 when a short circuit accident occurs between the R phase, the S phase, and the T phase of the transmission / distribution line, respectively. it is a diagram for explaining a second short-circuit current I _Ry1, I _Ry2. It is a figure which shows an example of a voltage suppression characteristic. It is a figure for demonstrating the conventional method which installs the overcurrent relay with a voltage suppression in each phase of a power transmission and distribution line, and protects from a short circuit accident. It is a figure for demonstrating the conventional method which aims at the protection from a short circuit accident by installing the overcurrent relay with a voltage suppression only in two phases by the transmission / distribution line etc. of a terminal circuit.

Explanation of symbols

1 power 2 ₁ to 2 ₃ first to third circuit breaker 3 ₁ to 3 ₃ first to third current transformer 41 _{to 3} first to third voltage overcurrent relay 6 potential transformers with suppressed 50 ₁ , 50 ₂ first and second overcurrent relays with voltage suppression I _R , I _S , _IT load currents I ₁ , I ₂ first and second load currents I _FR , I _FS , I _FT short-circuited current I _Ry1, I _Ry2 first and second short-circuit current V _R, V _S, V _T-phase voltage V _RS, V _ST, V _TR line voltage V _Ry suppression voltage θ impedance angle k1, k2 first and second Voltage value α, β Angle range

Claims (5)

An overcurrent relay device with voltage suppression for protecting a three-phase AC circuit from a short circuit accident,
A first current transformer (3 ₁ ) installed in the first phase of the three-phase AC circuit;
A second current transformer (3 ₂ ) installed in the second phase of the three-phase alternating current circuit and connected to the first current transformer;
A third current transformer (3 ₃ ) installed in the third phase of the three-phase AC circuit and connected in union with the second current transformer;
When a short-circuit fault is detected based on the first short-circuit current (I _Ry1 ) input from the sum-connected first and second current transformers and voltage information of the three-phase AC circuit, the three-phase AC A _first overcurrent relay with voltage suppression (50 ₁ ) that collectively shuts off _first to _third circuit breakers (2 ₁ to 2 ₃ ) installed in each phase of the circuit;
When a short circuit fault is detected based on the second short circuit current (I _Ry2 ) input from the sum-connected second and third current transformers and the voltage information, the first to third circuit breakers are detected. A second overcurrent relay with voltage suppression (50 ₂ ) that simultaneously shuts off
An overcurrent relay device with voltage suppression, comprising: The first and second overcurrent relays with voltage suppression use the one line voltage (V _TR ) and one phase voltage (V _R ) in a predetermined combination obtained from the voltage information, If the voltage is equal to or lower than the predetermined first voltage value (k1), it is determined that a short circuit accident has occurred, and the predetermined second voltage value (k2) in which the line voltage is larger than the first voltage value It is determined that a short circuit accident has occurred if the phase of the line voltage is delayed or advanced by a predetermined angle range (α) with reference to the phase of the line voltage before the short circuit accident as a reference. The overcurrent relay device with voltage suppression according to claim 1, wherein: The first and second overcurrent relays with voltage suppression are:
When the line voltage is equal to or less than the second voltage value and the phase of the line voltage is delayed by the angle range with reference to the phase of the line voltage before the short circuit accident, the three Determining that there is a short circuit accident between the first phase and the second phase of the phase AC circuit;
When the line voltage is equal to or less than the second voltage value and the phase of the line voltage is advanced by the angle range with reference to the phase of the line voltage before the short circuit accident, the three Determining a short circuit accident between the second phase and the third phase of the phase AC circuit;
The line voltage is less than or equal to the first voltage value, and the phase of the line voltage is delayed or advanced by the angle range with reference to the phase of the line voltage before the short circuit accident. The first phase of the three-phase AC circuit when the phase voltage phase is advanced by a predetermined angle range (β) with reference to the phase voltage phase before the short circuit accident. Determining that there is a short circuit accident between the phase and the third phase;
The line voltage is less than or equal to the first voltage value, and the phase of the line voltage is delayed or advanced by the angle range with reference to the phase of the line voltage before the short circuit accident. And when the phase of the phase voltage is not delayed or advanced only within the other angle range with reference to the phase of the phase voltage before the short circuit accident, the first phase of the three-phase AC circuit Determining a short circuit accident between one phase, the second phase and the third phase;
The overcurrent relay device with voltage suppression according to claim 2, wherein: The first and second overcurrent relays with voltage suppression are:
When it is determined that a short-circuit accident has occurred, a suppression voltage (V _Ry ) is calculated using the line voltage,
When the amplitudes of the first and second short-circuit currents exceed a current set value determined by a voltage suppression characteristic that defines a current set value according to the calculated suppress voltage, the first to third cutoffs Shut off all the devices at once,
The overcurrent relay device with voltage suppression according to claim 2 or 3, characterized in that. In the case of a short circuit accident between the first phase and the second phase of the three-phase AC circuit, only the second overcurrent relay with voltage suppression operates and the first to third All the circuit breakers
In the case of a short circuit accident between the second phase and the third phase of the three-phase AC circuit, only the first overcurrent relay with voltage suppression operates and the first to third All circuit breakers
The overcurrent relay device with voltage suppression according to claim 1, wherein the overcurrent relay device has voltage suppression.

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