JP2012157115A - Disconnection detection and protection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disconnection detection and protection device capable of protecting a transmission/distribution line by surely detecting a disconnection accident.SOLUTION: Trip signal generating means 14, 14, 15, and 15, under a condition that ground fault/short circuit accident determination means 13determines that no ground fault nor short circuit accident has occurred on a transmission/distribution line based on a ground fault protection relay operation signal Sand a short circuit protection relay operation signal S, outputs a trip signal Sfor shutting off A-phase, B-phase, and C-phase circuit breakers installed in A-phase, B-phase, and C-phase of the transmission/distribution line, when A-phase, B-phase, and C-phase current monitoring circuits 11, 11, and 11detect a disconnection accident based on the amount of variation in magnitude of A-phase, B-phase, and C-phase currents I, I, and I, otherwise AB-phase, BC-phase, and CA-phase inter-line current monitoring circuits 12, 12, and 12detect a disconnection accident based on the amount of variation in magnitude of AB-phase, BC-phase, and CA-phase inter-line currents I, I, and I.

Description

  The present invention relates to a disconnection detection and protection device suitable for protecting a transmission and distribution line from a disconnection accident.

In recent years, in transmission / distribution lines of 6 kV or less, the number of cases with a ground fault at the time of a disconnection accident has been reduced along with the use of an insulated wire, and therefore it has become difficult to selectively cut off by a ground fault protection relay.
Moreover, as a disconnection accident protection method, the reverse phase current relay method (46 relay method) that detects the reverse phase current at the time of the disconnection accident has been put into practical use, but since the disconnection cannot be reliably detected, The current situation is that no standard system is defined.

In addition, in the following patent document 1, the present applicant is able to accurately detect a one-wire disconnection without a ground fault and open the circuit breaker so that the live line state of the disconnected portion can be eliminated. An operational line determination unit that inputs the open / close state of the circuit breaker installed in the circuit to determine whether it is in a 1-line operation state or a 2-line operation state; A condition storage unit, a process activation unit that inputs the current value of each phase and detects that the current value of any one phase is equal to or less than a predetermined value, and is activated by the process activation unit. Based on the operation state of the line determined by the line determination unit, a calculation method of the operation state stored in the settling condition storage unit is extracted, and a phase angle calculation unit that calculates a phase angle according to the calculation method, and a phase angle calculation Calculated by the department It is determined whether or not the angle satisfies the settling condition.If the settling condition is satisfied, the motion calculation unit has motion detection, and the motion calculation unit has motion detection for one phase and has motion detection. When there is no operation detection for a phase other than the above phase, a disconnection protection relay is proposed that includes an operation determination unit that determines that this one phase has disconnection detection and outputs a disconnection detection signal.
Further, in Patent Document 2 below, a secondary circuit of a current transformer provided on a transmission / distribution line is provided with 3 to ensure that a one-wire disconnection accident can be reliably detected regardless of a one-line or two-line power transmission configuration. A first element for detecting that at least one phase current of the phase current is greater than or equal to a predetermined value, and a second element for detecting for each phase that the ratio of the interphase current to the maximum interphase current is less than or equal to a predetermined value 1 of a power transmission / distribution line provided with a current relay provided with an element, and determined to be a one-wire disconnection of the transmission / distribution line on condition of the operation of the first element and the two-phase operation of the second element A wire break detection circuit is disclosed.

JP 2009-81937 A JP-A-6-253446

However, the reversed-phase current relay system in practical use has the following problems.
(1) There is a risk of malfunction in a load with a large three-phase imbalance.
(2) 2-wire disconnection and 3-wire disconnection cannot be detected.
(3) In the branch line, it is difficult to detect the disconnection after the branch.

  The objective of this invention is providing the disconnection detection protection apparatus which can detect a disconnection accident reliably and can protect a power transmission and distribution line.

The disconnection detection / protection device of the present invention is a disconnection detection / protection device (10) for protecting a transmission / distribution line from a disconnection accident, wherein the first to third flows through the first to third phases of the transmission / distribution line. The magnitudes of the phase currents (I _A , I _B , I _C ) of the first and third phase currents are monitored based on the amount of change in the magnitudes of the first to third phase currents. First to third phase current monitoring means (11 _A , 11 _B , 11 _C ) for detecting whether or not a disconnection accident has occurred in the phase; and first to third line currents ( I _AB , I _BC , I _CA ) are monitored, and a disconnection accident occurs in the first to third phases of the transmission / distribution line based on the amount of change in the magnitude of the first to third line currents. the first to third of the line current monitoring means but for detecting whether the generated _{(12 a, 12 B, 12} C) and, the installed ground fault protection relay and short holding the electric transmission Based on the ground protection relay operation signal input from the relay (S _67G) and short-circuit protection relay operation signal (S _51), determine whether a ground fault and short-circuit fault has not occurred in said transmission distribution line The ground fault / short circuit accident judging means (13 ₃ ) and the ground fault / short circuit accident judging means for determining that the ground fault and short circuit accident have not occurred in the transmission / distribution line. When at least one of the first to third phase current monitoring means and the first to third line current monitoring means detects a disconnection accident of the transmission and distribution lines, the first to third of the transmission and distribution lines Trip signal generating means (14 ₁ , 14 ₂ , 15 ₄ , 15 ₅ ) for outputting a trip signal (S _T ) for breaking the first to third circuit breakers installed in the phase. It is characterized by.
Here, the first to third undervoltage relay operation signals (S _27A , S _27B , S) input from the first to third under voltage relays installed in the first to third phases of the transmission / distribution line First fail-safe means (13 ₄ ) for determining whether or not a ground fault and a short-circuit accident have occurred in the transmission / distribution line based on S _27C ), and the first to the first of the transmission / distribution line Based on the first to third tidal current detection relay operation signals (S _57A , S _57B , S _57C ) input from the first to third tidal current detection relays installed in the third phase, Second fail-safe means (15 ₁ to 15 ₃ , 13 ₅ ) for determining whether or not there is a power flow in at least one of the first to third phases; and the _first to _third breakers The first to third circuit breakers are turned on based on the first to third circuit breaker input signals input from Dolphin third fail-safe means for determining whether (15 ₄₎ and further comprising, said trip signal generating means, the first fail-safe means a ground fault and short-circuit fault occurs in electric transmission It is further determined that the second fail-safe means determines that there is no power flow in at least one of the first to third phases of the transmission and distribution line. As an alternative, the trip signal may be output.
When at least one of the first to third phase current monitoring means and the first to third line current monitoring means detects a disconnection accident of the transmission / distribution line, it is installed on the opposite end side of the transmission / distribution line Further comprising a disconnection detection signal transmission means for transmitting the end-side disconnection detection signal (S ₁ ) to another disconnection detection protection apparatus having the same configuration as that of the disconnection detection protection apparatus, and the trip signal generation means comprises the trip signal generation means, That at least one of the first to third other phase current monitoring means and the first to third other line current monitoring means of the other disconnection detection protection device has detected a disconnection accident of the transmission and distribution lines; The trip signal may be output on condition that the opposite end side disconnection detection signal (S ₂ ) shown is transmitted from the other disconnection detection protection device.
The trip signal generating means may further comprise timers (14 ₁ , 14 ₂ ) for sending and outputting the trip signal for the cooperation time with the ground fault protection relay.
The trip signal generating means may further comprise another timer (14 ₃ ) for outputting the trip signal delayed by a transmission delay of the opposite-end-side disconnection detection signal.

The disconnection detection protection device of the present invention has the following effects.
(1) On condition that no ground fault or short circuit accident has occurred in the transmission / distribution line, if a disconnection accident is detected based on the amount of change in each phase current and the amount of change in each line current, By outputting a trip signal for interrupting the phase breaker, it is possible to reliably detect a disconnection accident and protect the transmission and distribution lines.
(2) The disconnection detection accuracy can be improved.
(3) It can be applied to both a resistance grounding system and a non-grounding system.
(4) It is possible to select whether it is self-end determination or comprehensive determination with the opposite end according to the system status.

It is a figure which shows the structure of the disconnection detection protection apparatus 10 by one Example of this invention. It is a figure for demonstrating operation | movement of the disconnection detection protection apparatus 10 shown in FIG. 1 when the A phase of a power transmission / distribution electric wire is completely disconnected. It is a figure for demonstrating operation | movement of the disconnection detection protection apparatus 10 shown in FIG. 1 when the A phase of a transmission / distribution electric wire is incompletely disconnected.

  For the above purpose, on condition that no ground fault or short circuit accident has occurred in the transmission / distribution line, detect a disconnection accident based on the amount of change in the magnitude of each phase current or change in the magnitude of each line current This was realized by outputting a trip signal to shut off each phase breaker when a disconnection accident was detected based on the quantity.

Embodiments of the disconnection detection protection device of the present invention will be described below with reference to the drawings.
The disconnection detection and protection device of the present invention monitors the phase current and the line current before and after the disconnection accident so that the two-wire disconnection accident and the three-wire disconnection accident of the transmission and distribution lines can be detected. When the magnitude of at least one of the two phase currents is less than 5% of the magnitude of each phase current three cycles before, it is determined that a “disconnection accident has occurred” and of the three line current variations "A disconnection accident occurred" when at least one line current change amount is 5% or more of the phase current and the phase angle between the line current and the phase current is in the range of 0 ° to 5 °. As an example, the case of determining that the

The disconnection detection and protection device 10 according to one embodiment of the present invention is installed at both ends of the transmission / distribution line. As shown in FIG. 1, the A-phase, B-phase and C-phase current monitoring circuits 11 _A , 11 _B , 11 _C , AB phase, BC phase, and CA phase line current monitoring circuits 12 _AB , 12 _BC , 12 _CA , first to fifth OR circuits 13 _{1 to} 13 _5, and first to third timers 14 _{1 to} 14 ₃ and _first to _fifth AND circuits 15 ₁ to 15 ₅ .

Here, the A-phase current monitoring circuit 11 _A is input from the local end side of the installed not shown A phase (disconnection detection protection device 10 is installed side) A current transformer of the transmission and distribution lines monitoring the size of the a-phase current I _a, when the size of the a-phase current I _a is less than 5% of the size of three cycles before the a-phase current I _a, the disconnection accident "a phase It determines generated ", and outputs an output signal of high level to a first logic OR circuit 13 _1.
Similarly, the B-phase current monitoring circuit 11 _B monitors the magnitude of the B-phase current I _B input from a B-phase current transformer (not shown) installed in the B-phase on the own end side of the transmission and distribution line. If the size of the B phase current I _B is less than 5% of the size of the three cycles before B phase current I _B, it is determined that "disconnection accident occurred in phase B ', the high-level output The signal is output to the _first OR circuit 13 ₁ .
Further, the C-phase current monitoring circuit 11 _C monitors the magnitude of the C-phase current I _C input from a C-phase current transformer (not shown) installed in the C-phase on the own end side of the transmission and distribution line. If the magnitude of the phase current I _C is less than 5% of the size of 3 cycles ago C phase current I _C, it is determined that "disconnection accident occurred in phase C ', the high level of the output signal Is output to the _first OR circuit 13 ₁ .

The AB phase line current monitoring circuit 12 _AB is based on the A phase current I _A inputted from the A phase current transformer and the B phase current I _B inputted from the B phase current transformer. monitoring the size of the _AB, (the absolute value of the difference between the magnitude of the immediately preceding cycle AB phase line between the current change amount [Delta] I _AB) AB phase line between the current change amount [Delta] I _AB is a B-phase current I _B the magnitude of the is 5% or more, and, when the phase angle between AB phase line current between I _AB and B phase current I _B is in the range of 0 ° to 5 °, the "disconnection accident a phase occurs" determined to a to output an output signal of high level to the ₂ second OR circuit 13.
Similarly, the BC phase line current monitoring circuit 12 _BC is configured to generate a BC phase line based on the B phase current I _B input from the B phase current transformer and the C phase current I _C input from the C phase current transformer. monitoring the magnitude between the current I _BC, (the absolute value of the difference between the magnitude of the immediately preceding cycle BC phase line between the current change amount [Delta] I _BC) BC phase line between the current change amount [Delta] I _BC is C-phase current I _C If it is 5% or more of the magnitude and the phase angle between the BC phase line current I _BC and the C phase current I _C is in the range of 0 ° to 5 °, “the B phase is broken. It determines generated ", and outputs an output signal of high level to a second logical sum circuit 13 _2.
Further, the CA phase line current monitoring circuit 12 _CA is _arranged between the CA phase lines based on the C phase current I _C input from the C phase current transformer and the A phase current I _A input from the A phase current transformer. It monitors the magnitude of the current I _CA, (absolute value of the difference between the size of one cycle before the CA phase line between the current change amount [Delta] I _CA) CA phase line between the current change amount [Delta] I _CA is a phase current I _a size If the phase angle between the CA phase line-to-line current I _CA and the A phase current I _A is in the range of 0 ° to 5 °, a “C phase disconnection accident has occurred. it is determined that the "outputs an output signal of high level to a second logical sum circuit 13 _2.

The first OR circuit 13 ₁ (OR circuit) takes the OR of the output signals of the A-phase, B-phase, and C-phase current monitoring circuits 11 _A , 11 _B , 11 _C.
The second OR circuit 13 ₂ (OR circuit) takes the OR of the output signals of the AB phase, BC phase, and CA phase line current monitoring circuits 12 _AB , 12 _BC , and 12 _CA.

The third OR circuit 13 ₃ (OR circuit), when a ground fault or a short circuit accident electric transmission occurs intended to be so trip signal S _T from the disconnection detection protection device 10 is not output Yes, a ground fault direction relay operation signal S _67G (a signal that becomes high when the ground fault direction relay operates) is input from a ground fault direction relay (67G) (not shown) installed on the own end of the transmission / distribution line. Inverted signal and inverted signal of overcurrent relay operation signal S ₅₁ (a signal that becomes high level when the overcurrent relay is operated) input from an unillustrated overcurrent relay (51) installed on the end of the transmission / distribution line. OR with.

The first timer 14 ₁ is for cooperation with the ground fault direction relay, and outputs the output signal of the first OR circuit 13 _{1 with} a delay of one second. That is, when a high level output signal is input from the _first OR circuit 13 ₁ , the first timer 14 ₁ outputs a high level output signal with a delay of 1 second.
Similarly, the second timer 14 ₂ is for coordinating with the ground fault direction relay, and outputs the output signal of the _second OR circuit 13 _{2 with} a delay of 1 second. That is, when the high-level output signal is input from the _second OR circuit 13 ₂ , the second timer 14 ₂ outputs a high-level output signal with a delay of 1 second.

The fourth OR circuit 13 ₄ (NOR circuit) pays attention to the fact that the voltage of the bus at the end of the transmission / distribution line decreases at the time of a short-circuit accident but does not decrease at the time of the disconnection accident. In order to add as a fail-safe element that the A-phase, B-phase and C-phase undervoltage relays (27) (not shown) installed in the phases C and C are not operating, A phase, B phase, and C phase undervoltage relay operation signals S _27A , S _27B , S _27C (high-level when the A phase, B phase, and C phase under voltage relays are operated) (Or signal) is taken.

The first to _third AND circuits 15 ₁ to 15 ₃ (AND circuit) and the fifth OR circuit 13 ₅ (OR circuit) are connected to one or more of the A phase, B phase, and C phase of the power transmission and distribution line. This is to add that there is a tidal current as a fail-safe element.
Therefore, the first AND circuit 15 _1, the A-phase power flow detection relay operation signal S _57A input from local end side of the installed not shown to the A-phase A-phase power flow detection relay of transmission and distribution lines (57) Inverted signal (signal that becomes high level when the A-phase power flow detection relay is operated) and B-phase power flow detection input from a B-phase power flow detection relay (not shown) installed in the B phase on the own end of the transmission / distribution line Relay operation signal S _57B (a signal that goes high when the B-phase power flow detection relay operates) and a C-phase signal input from a C-phase power flow detection relay (not shown) installed on the C-phase on the own end of the transmission and distribution line The logical product of the power detection relay operation signal S _57C (a signal that becomes high level when the C-phase power flow detection relay operates) is obtained.
Second AND circuit 15 _2, the logical product of an inverted signal and the C-phase power flow detection relay operation signal S _57C of the A-phase power flow detection relay operation signal S _57A and B-phase power flow detection relay operation signal S _57B.
The third AND circuit 15 ₃ takes a logical product of the A phase power flow detection relay operation signal S _57A , the B phase power flow detection relay operation signal S _57B, and the inverted signal of the C phase power flow detection relay operation signal S _57C .
The fifth logical sum circuit 13 ₅ takes the logical sum of the output signals of the _first to _third logical product circuits 15 ₁ to 15 ₃ .

The fourth AND circuit 15 ₄ includes the output signals of the first and second timers 14 ₁ and 14 ₂ , the output signals of the third to fifth OR circuits 13 _{3 to} 13 ₅ , and the end of the transmission / distribution line. A phase, B phase and C phase circuit breaker input signals S _CBA , S _CBB , S input from A phase, B phase and C phase circuit breakers (not shown) installed in the A phase, B phase and C phase on the side Logical product with _CBC (signal which becomes high level when the A-phase, B-phase and C-phase circuit breakers are in the on state) is taken.
Here, the A-phase, B-phase, and C-phase circuit breaker input signals S _CBA , S _CBB , S _CBC are when the A-phase, B-phase, and C-phase circuit breakers are cut off when the transmission / distribution line is _operated . It is for adding as a fail-safe element for locking the disconnection detection protection apparatus 10 to the above.
The output signal of the _fourth AND circuit 15 ₄ is a disconnection installed on the opposite end side of the transmission / distribution line as a self-side disconnection detection signal S ₁ indicating that a disconnection accident has been detected by the disconnection detection protection device 10. The data is transmitted to the detection protection device 10 (hereinafter, referred to as “disconnection detection protection device 10 on the opposite end side”) via a transmission circuit and a communication line (not shown).

Fifth AND circuit 15 _5, disconnection accident by breaking detection protector 10 opposing end side disconnection detection signal S ₂ (the opposite end from the disconnection detection protection device 10 of the opposite end side transmitted via the communication line When the signal is detected, the signal becomes a high level) and the output signal of the _fourth AND circuit 15 ₄ is ANDed.

Third timer 14 ₃ is obtained by considering the transmission delay of the communication line to output a disconnection detection protection device 10 simultaneously trip signal S _T of the opposite end, the fifth AND circuit 15 ₅ of the output signal of the Is output with a delay of 2 seconds. That is, when a high level output signal is input from the _fifth AND circuit 15 ₅ , the third timer 14 ₃ outputs a high level output signal with a delay of 2 seconds.
The output signal of the third timer 14 _3, local end side of the A-phase as the trip signal S _T, is output to the B-phase and C-phase circuit breaker. Thus, A-phase local end side, B-phase and C-phase circuit breaker is blocked by the high level trip signal S _T.

Next, the operation of the disconnection detection protection device 10 in the normal state will be described with reference to FIG.
When there is no disconnection accident in the transmission / distribution line, the A phase, B phase, and C phase currents of the same magnitude as shown in FIG. I _A , I _B and I _C continue to flow with a phase difference of 120 °.
Therefore, the A-phase current monitoring circuit 11 _A is, the A-phase current change amount [Delta] I _A = 0 (i.e., the size of the A-phase current I _A of size = 3 cycles before the phase A current I _A), and therefore, " It is determined that a disconnection accident does not occur in phase A, and the low level output signal is still output.
Similarly, the B-phase current monitoring circuit 11 _B and the C-phase current monitoring circuit 11 _C still output a low level output signal.
As a result, the first OR circuit 13 ₁ is also remains outputs a low level output signal, the output signal of the fourth AND circuit 15 ₄ will remain low, a trip signal S _T also remains at a low level is there.

Next, the operation of the disconnection detection protection device 10 when the phase A of the transmission / distribution line is completely disconnected will be described with reference to FIG. 2 (b), FIG. 3 (a), and (b).
When the A phase of the transmission / distribution line is completely disconnected, as shown in FIG. 2B, the A phase current I _a = 0 after the A phase disconnection accident and the B phase current I _b after the A phase disconnection accident is obtained. The C phase current I _c has the same magnitude as the B phase current I _B and the C phase current I _{C in the} normal state, and a phase difference = 180 °.
Therefore, the A-phase current monitoring circuit 11 _A has the A-phase current change amount ΔI _A = | I _A | (that is, the magnitude of the A-phase current I _a after the A-phase disconnection accident = 0 (the A-phase current three cycles before). since the I less than 5% of the magnitude of _a)), a determination of "disconnection phase a fault has occurred", and outputs an output signal of high level to a first logic OR circuit 13 _1.
As a result, the output signal of the _first OR circuit 131 changes from the low level to the high level.

Further, as shown in FIG. 3 (b), AB between phase line current after the A-phase disconnection fault I _ab = -I _b = for the -I _B, AB-phase line-to-line current change amount ΔI _AB = | I _AB | − | I _ab | = (3 ^1/2 −1) · | I _B | ≈0.73 · | I _B | (that is, the AB phase line current I _ab after the A phase disconnection accident is the A phase disconnection accident equal to or greater than 5%) of B-phase current I _b after. The phase angle between the AB phase line current I _ab after the A phase disconnection accident and the B phase current I _b after the A phase disconnection accident is 0 ° (that is, the AB phase line current I _ab after the A phase disconnection accident). And the phase angle between the B-phase current I _b after the A-phase disconnection accident is within the range of 0 ° to 5 °.
Thus, AB-phase line-to-line current monitoring circuit 12 _AB, it is determined that "breakage accident A phase occurs", and outputs an output signal of high level to a second logical sum circuit 13 _2.
As a result, the output signal of the _second OR circuit 132 is changed from the low level to the high level.

Since the ground fault direction relay and the overcurrent relay do not operate even if the A phase of the power transmission / distribution line is completely disconnected, both the ground fault direction relay operation signal S _67G and the over current relay operation signal S ₅₁ remain at the low level.
As a result, the output signal of the _third OR circuit 133 remains at a high level.

The A-phase, B-phase, and C-phase undervoltage relays do not operate even if the A-phase of the transmission / distribution line is completely disconnected, so the A-phase, B-phase, and C-phase undervoltage relay operation signals _S27A , _S27B , _S27C All remain low.
As a result, the output signal of the _fourth OR circuit 134 remains at a high level.

When the A phase of the transmission / distribution line is completely disconnected, the B phase and C phase power flow detection relays remain in operation, but the B phase and C phase power flow detection relay operation signals S _57B and S _57C remain at high level. Since the A-phase power flow detection relay does not operate, the A-phase power flow detection relay operation signal S _{57A changes} from the high level to the low level.
As a result, since the output signal of the _first AND circuit 151 is changed from the low level to the high level, the output signal of the _fifth OR circuit 135 is changed from the low level to the high level.

As a result, the output signal of the _fifth AND circuit 15 ₅ changes from the low level to the high level, so that the high-level self-end-side disconnection detection signal S ₁ is sent to the opposite-end-side disconnection detection protection device 10 via the communication line. Is transmitted.

At this time, also in the disconnection detection protection device 10 of the opposite end, the complete disconnection of the A-phase of transmission and distribution lines are detected in a similar manner, the opposite side disconnection detection signal S ₂ of the high-level of the opposite end side disconnection detection It is transmitted from the protection device 10 via a communication line.

As a result, when all of the A-phase, B-phase, and C-phase circuit breakers on the end side are turned on, the output signal of the _fifth AND circuit 155 changes from low level to high level. a phase S _T disconnection detection from the protection device 10 itself end side, are outputted to the B-phase and C-phase circuit breaker, the a-phase of the self-end side, B-phase and C-phase circuit breaker is interrupted.
Similarly, the A-phase, B-phase, and C-phase circuit breakers on the opposite end side are also interrupted by the disconnection detection protection device 10 on the opposite end side.

Next, the operation of the disconnection detection protection device 10 when the phase A of the transmission / distribution line is incompletely disconnected will be described with reference to FIGS. 2 (c) and 3 (c).
When the A-phase of the transmission and distribution lines are incompletely broken, as shown in FIG. 2 (c), the size of the A-phase current I _a of the A-phase disconnection accident of normal A-phase current I _B size The B-phase and C-phase currents I _b , I _c after the A-phase disconnection accident are the same as the normal B-phase and C-phase currents I _B , I _C , The phase difference is larger than 120 ° and smaller than 180 ° in accordance with the magnitude of the phase current I _a (in the illustrated example, the phase difference is approximately 170 °).
Therefore, when the A-phase current I _a of the A-phase disconnection fault is less than 5% of the size of the three cycles before the phase A current I _A, a determination of "disconnection accident has occurred in the A-phase" high The level output signal is output to the first OR circuit 13 ₁ .
As a result, the output signal of the _first OR circuit 131 changes from the low level to the high level.

Further, as shown in FIG. 3C, the AB phase line current change amount ΔI _AB = | I _AB | − | I _ab |, and the AB phase line current I _ab and the A phase disconnection after the A phase disconnection accident The phase angle with the B-phase current I _b after the accident is greater than 0 ° and smaller than 30 ° according to the magnitude of the A-phase current I _a after the A-phase disconnection accident (in the illustrated example, the phase difference ≒ 15 °).
Therefore, the AB phase line current monitoring circuit 12 _AB is such that the AB phase line current I _ab after the A phase disconnection accident is 5% or more of the B phase current I _b after the A phase disconnection accident, and the A phase disconnection If the phase angle between the AB phase line current I _ab after the accident and the B phase current I _b after the A phase disconnection accident is within the range of 0 ° to 5 °, “A phase disconnection accident occurred. "determined to a to output an output signal of high level to a second logical sum circuit 13 _2.
As a result, the output signal of the _second OR circuit 132 is changed from the low level to the high level.

Since the A-phase of the transmission and distribution lines are ground direction relay and the overcurrent relay does not operate even if incomplete disconnection, ground fault direction relay operation signal S _67G and overcurrent relay operating signal S ₅₁ are both kept at a low level.
As a result, the output signal of the _third OR circuit 133 remains at a high level.

Even if the A phase of the transmission and distribution line is incompletely disconnected, the A phase, B phase, and C phase undervoltage relays do not operate. Therefore, the A phase, B phase, and C phase undervoltage relay operation signals S _27A , S _27B , S _27C All remain low.
As a result, the output signal of the _fourth OR circuit 134 remains at a high level.

If the A phase of the transmission / distribution line is disconnected to the extent that the AB phase line current monitoring circuit 12 _{AB determines} that “A phase disconnection has occurred”, the B phase and C phase power flow detection relays remain in operation. The B-phase and C-phase power flow detection relay operation signals S _57B and S _57C remain at the high level, but the A-phase power flow detection relay does not operate, so the A-phase power flow detection relay operation signal S _57A is at the low level.
As a result, since the output signal of the _first AND circuit 151 is changed from the low level to the high level, the output signal of the _fifth OR circuit 135 is changed from the low level to the high level.

As a result, the output signal of the _fifth AND circuit 15 ₅ changes from the low level to the high level, so that the high-level self-end-side disconnection detection signal S ₁ is sent to the opposite-end-side disconnection detection protection device 10 via the communication line. Is transmitted.

At this time, also in the disconnection detection protection device 10 of the opposite end, the accidental disconnection of the A-phase of transmission and distribution lines in the same manner is detected, disconnection opposite end disconnection detection signal S ₂ of the high-level of the opposite end It is transmitted from the detection protection device 10 via a communication line.

As a result, when all of the A-phase, B-phase, and C-phase circuit breakers on the end side are turned on, the output signal of the _fifth AND circuit 155 changes from low level to high level. a phase S _T disconnection detection from the protection device 10 itself end side, are outputted to the B-phase and C-phase circuit breaker, the a-phase of the self-end side, B-phase and C-phase circuit breaker is interrupted.
Similarly, the A-phase, B-phase, and C-phase circuit breakers on the opposite end side are also interrupted by the disconnection detection protection device 10 on the opposite end side.

In the above description, the disconnection detection protection device 10 has the fifth AND circuit 15 ₅ in order to adopt a comprehensive determination method between the own end and the opposite end (power transmission end and power reception end) so that disconnection after the branch can also be detected. Although provided with, in the case of performing only the local end determination may not be provided with the aND circuit 15 ₅ of the fifth. In this case, the output signal of the _fourth AND circuit 15 ₄ may be directly input to the third timer 14 ₃ , and the self-end-side disconnection detection signal output from the _fourth AND circuit 15 ₄ It is not necessary to transmit S ₁ to the disconnection detection protection device 10 on the opposite end side via the communication line.
In addition, in order to enable selection between self-end determination and comprehensive determination depending on the system status, a switch that causes the opposite-end-side disconnection detection signal S ₂ to be input to the _fifth AND circuit 15 ₅ only when comprehensive determination is performed. May be provided between the input terminal of the opposite-end-side disconnection detection signal S ₂ and the fifth AND circuit 15 ₅ .

As trip signal S _T is not outputted when tested, by not using the disconnection detection protection device 10, the a closing switch apparatus used in the signal is input and the fifth timer 14 ₃ and an output terminal of the trip signal S _T You may provide between.
Also, when there is a power flow in all of the A-phase, B-phase, and C-phase of the transmission and distribution lines, the A-phase, B-phase, and C-phase power flow detection relay operation signal S _57A , so that the trip signal _ST is not output reliably. S _57B, by providing a logical product circuit (aND circuit) ANDing S _57C, the output signal of the logical product circuit and the output terminal of the fifth timer 14 ₃ and the trip signal S _T at the high level You may make it close the switch provided in between.

To ensure that the trip signal S _T from the disconnection detection protection device 10 is not output when the ground fault or a short circuit accident electric transmission occurs, the ground fault direction relay operation signal S _67G third OR circuit 13 has been inputted to the _3, if the local end side on the ground fault over-voltage relay transmission and distribution lines (64V) is installed, enter the ground fault over-voltage relay operating signal to the third OR circuit 13 ₃ Also good.

10 disconnection detection protection device 11 _A , 11 _B , 11 _C A phase, B phase and C phase current monitoring circuit 12 _AB , 12 _BC , 12 _CA AB phase, BC phase and CA phase line current monitoring circuit 13 _{1 to} 13 ₅ 1st to 5th OR circuits 14 _{1 to} 13 _{3 1st} to 3rd timers 15 ₁ to 15 _{5 1st} to _5th AND circuits I _A , I _B , I _C A phase, B phase and C Phase currents I _a , I _b , I _c A phase, B phase and C phase currents ΔI _A , ΔI _B , ΔI _C A phase, B phase and C phase current variations I _AB , I _BC , I _CA AB phase, BC phase and CA phase line current I _ab A phase AB line current after the A phase disconnection accident ΔI _AB , ΔI _BC , ΔI _CA AB phase, BC phase and CA phase line current change S _67G fault direction relay operation signal S ₅₁ overcurrent relay operating signal _{S 27A, S 27B, S 27C} A phase, B phase and C phase undervoltage relay operation signal S _57A, S _{5 7B} , S _57C A phase, B phase and C phase power flow detection relay operation signal S _CBA , S _CBB , S _CBC A phase, B phase and C phase circuit breaker input signals S ₁ , S ₂ Own end side and opposite end side disconnection Detection signal _ST Trip signal

Claims (5)

A disconnection detection protection device (10) for protecting a transmission / distribution line from a disconnection accident,
The magnitudes of the first to third phase currents (I _A , I _B , I _C ) flowing through the first to third phases of the transmission / distribution line are monitored, and the first to third phase currents are monitored. First to third phase current monitoring means (11 _A , 11 _B , 11) for detecting whether or not a disconnection accident has occurred in the first to third phases of the transmission / distribution line based on the change in size. _C ) and
The magnitudes of the first to third line currents (I _AB , I _BC , I _CA ) of the transmission / distribution lines are monitored and based on the amount of change in the magnitudes of the first to third line currents. First to third line current monitoring means (12 _A , 12 _B , 12 _C ) for detecting whether or not a disconnection accident has occurred in the first to third phases of the transmission and distribution lines;
Based on the ground fault protection relay operation signal (S _67G ) and the short circuit protection relay operation signal (S ₅₁ ) input from the ground fault protection relay and the short circuit protection relay installed on the transmission and distribution line, A ground fault / short circuit accident judging means (13 ₃ ) for judging whether or not a fault accident and a short circuit accident have occurred;
The first to third phase current monitoring units and the first phase are provided on the condition that the ground fault / short circuit accident determination unit determines that no ground fault or short circuit accident has occurred in the transmission / distribution line. When at least one of the third to third line current monitoring means detects a disconnection accident of the transmission / distribution line, the first to third circuit breakers installed in the first to third phases of the transmission / distribution line Trip signal generating means (14 ₁ , 14 ₂ , 15 ₄ , 15 ₅ ) for outputting a trip signal (S _T ) for cutting off
A breakage detection protection device comprising: First to third undervoltage relay operation signals (S _27A , S _27B , S _27C ) input from first to third undervoltage relays installed in the first to third phases of the transmission and distribution lines. A first fail-safe means (13 ₄ ) for determining whether or not a ground fault and a short-circuit accident have occurred in the transmission and distribution line,
First to third tidal current detection relay operation signals (S _57A , S _57B , S _57C ) input from first to third tidal current detection relays installed in the first to third phases of the transmission and distribution lines. A second fail-safe means (15 ₁ to 15 ₃ , 13 ₅ ) for determining whether or not there is a power flow in at least one of the first to third phases of the transmission and distribution line,
A third fail for determining whether or not the first to third circuit breakers are turned on based on first to third circuit breaker input signals input from the first to third circuit breakers. Safe means (15 ₄ ),
The trip signal generating means determines that the first fail-safe means has not caused a ground fault or a short-circuit accident in the transmission / distribution line, and the second fail-safe means is the delivery / distribution. The trip signal is output on the further condition that it is determined that there is no power flow in at least one of the first to third phases of the wire.
The disconnection detection protection apparatus according to claim 1, wherein When at least one of the first to third phase current monitoring means and the first to third line current monitoring means detects a disconnection accident of the transmission / distribution line, it is installed on the opposite end side of the transmission / distribution line A disconnection detection signal transmission means for transmitting the end-side disconnection detection signal (S ₁ ) to the other disconnection detection protection device having the same configuration as that of the disconnection detection protection device,
The trip signal generating means is configured such that at least one of the first to third other phase current monitoring means and the first to third other line current monitoring means of the other disconnection detection protection device is the transmission / distribution line. The trip signal is output on the condition that the opposite-end-side disconnection detection signal (S ₂ ) indicating that the disconnection accident is detected is transmitted from the other disconnection detection protection device,
The disconnection detection protection device according to claim 1, wherein the disconnection detection protection device is provided. The trip signal generating means further comprises timers (14 ₁ , 14 ₂ ) for sending and outputting the trip signal for a cooperation time with the ground fault protection relay. Disconnection detection protection apparatus in any one. 5. The trip signal generating means further comprises another timer (14 ₃ ) for outputting the trip signal delayed by a transmission delay of the opposite-end-side disconnection detection signal. The disconnection detection protection device described.

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