JP2008161013A - Ground fault overcurrent relay device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground fault overcurrent relay device for a power supply end, capable of remarkably shortening a fault eliminating time. <P>SOLUTION: A first ground fault overcurrent relay device 10<SB>1</SB>for power supply end disposed on a power supply end of an own line 1L of a parallel dual power transmission line includes a trip signal generating circuit 20 for generating a first trip signal S<SB>1</SB>for interrupting a first breaker 4<SB>1</SB>provided on the power supply end side of the own line 1L when detecting a ground fault in the own line 1L. The trip signal generating circuit 20 includes an own line fault determining circuit 25 for obtaining a value calculated by dividing the difference between a first zero phase current I<SB>01</SB>and a second zero phase current I<SB>02</SB>by the sum of the first zero phase current I<SB>01</SB>and the second zero phase current I<SB>02</SB>, and outputting an output signal when the obtained value is not less than a threshold value; and a third logical AND circuit 23<SB>3</SB>for obtaining logical AND between an output signal of the own line fault determining circuit 25 and a second contact point signals S<SB>C2</SB>to be inputted from a second breaker 4<SB>2</SB>provided on the power supply end side of the other line 2L. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ground fault overcurrent relay device, and more particularly to a ground fault overcurrent relay device suitable for installation on the power supply end side of a balanced two-line power transmission line.

Generally, a ground fault overcurrent relay device (OCG) used for protection in the event of a ground fault in a power system is an electric quantity (zero phase current) of its own line (a transmission line in which the ground fault overcurrent relay device is installed). Other ground fault overcurrent relays installed on the transmission line behind the opposite end (non-power source) to determine the fault section based on the magnitude of I ₀ ) And time cooperation (accumulation of 0.4 s to 0.5 s).
Therefore, in the ground fault overcurrent relay installed at the power supply end side, as will be described below, the accident elimination time becomes longer, so the ground fault overcurrent relay is used as a back-up protection in the balanced two-line transmission line. In addition, the accident removal time is shortened by installing a separate main protection relay device that operates instantaneously due to a ground fault in the protection section.

As shown in FIG. 4, a first power transmission line 1L (hereinafter referred to as “own line 1L”) and a second power transmission line 2L branched from a bus line supplied with power from a power source 1 (zero-phase power source). (Hereinafter referred to as “other line 2L”) on the power supply end side (bus side) (see “first and second power supply ground fault overcurrent relay devices 110 ₁ , 110 _2”). ) Are installed, and ground fault direction relay devices (hereinafter referred to as “first and second opposite end ground fault direction relays) are provided on the opposite end side (opposite side of the bus line) of the own line 1L and the other line 2L. It is assumed that electrical devices (DG) 120 ₁ and 120 ₂ are referred to).

The first power supply ground fault overcurrent relay device 110 ₁ includes a first zero phase current I input from a first zero phase current transformer (ZCT) 3 ₁ installed on the power supply end side of the own line 1L. _{When the} occurrence of a ground fault in the own line 1L is detected based on ₀₁ , a first trip signal S ₁ for breaking the _first circuit breaker 41 installed on the power supply end side of the own line 1L is generated.
A second power supply terminal land fault overcurrent relay device 110 _2, a second zero-phase current I ₀₂ Based on other lines 2L inputted second from the zero-phase current transformer 3 ₂ installed on the other line 2L Is detected, the second trip signal S ₂ for breaking the second circuit breaker 4 ₂ installed on the power supply end side of the other line 2L is generated.

The first opposing ground fault direction relay device 120 ₁ has a second grounded-type instrument transformer (EVT) 2 ₂ provided on the opposing end bus (hereinafter referred to as “opposing end bus”). on the basis of the third zero-phase current I ₀₃ inputted from the third zero-phase current transformer 3 ₃ installed on the opposite end side of the opposite end zero-phase voltage V _0b and self line 1L inputted from the self Upon detection of the ground fault occurs in the line 1L, to generate a third trip signal S ₃ for blocking the third breaker 4 ₃ placed on the opposite end of its own line 1L.
Second opposing end ground fault direction relay device 120 _2, first installed in the opposite end of the second earth type instrument transformer 2 ₂ opposing end zero-phase voltage input from V _0b and other line 2L Upon detection of the ground fault occurs in the other line 2L based from the zero-phase current transformer 3 ₄ 4 to the fourth zero-phase current I ₀₄ inputted, 4th placed on opposite end of the other line 2L generating a breaker 4 ₄ 4 trip signal S ₄ of for blocking the.

The first power source ground fault overcurrent relay device 110 ₁ includes a trip signal generation circuit 130 as shown in FIG. 5 in order to generate the _first trip signal S ₁ .
Here, the trip signal generation circuit 130 includes a relay determination circuit 131, first to third delay circuits (timers) 132 _{1 to} 132 ₃ , an AND circuit 133, and an OR circuit 134.

Relay determination circuit 131 detects a ground fault generated in the own line 1L based on the magnitude of the first zero-phase current I _01, and outputs an output signal of high level.
The first delay circuit 132 ₁ delays the first OVG output signal S _OVG1 inputted from the first ground fault over-voltage relay device (OVG) 5 ₁ Only first timed coordination time T1 _1. Here, the first ground fault over-voltage relay device 5 _1, first of setpoint or magnitude of the power supply terminal zero-phase voltage V _0a inputted from earth type potential transformer 2 ₁ provided in bus Then, a high-level first OVG output signal S _OVG1 is output. The first timed coordination time T1 ₁ is set for the timed coordination with other ground fault overcurrent relay apparatus installed at opposite ends behind the transmission line of its own line 1L (not shown) (e.g. Set to 800 ms).
AND circuit 133 takes a logical product of the output signal and the first OVG output signal S _OVG1 by the first delay circuit 132 ₁ is delayed first by timed coordination time T1 the _first relay determining circuit 131.
The second delay circuit 132 ₂ delays the output signal of the logical product circuit 133 by the first zero-phase free vibration malfunction prevention time T2 ₁ . Here, the first zero-phase free vibration lockout time T2 ₁ is the zero-phase free vibration is set to prevent malfunction due to (after the accident point disconnecting also the zero-phase voltage only remains phenomenon predetermined time) (typically 100ms To be set). The first operation of the power supply terminal land fault overcurrent relay device 110 ₁ timed T _OCG1 the total time of the first time period coordinated time T1 ₁ and the first zero-phase free vibration lockout time T2 ₁ (T _OCG1 = T1 ₁ + T2 ₁ ).
The third delay circuit 132 ₃ delays the first OVG output signal S _OVG1 inputted from the first ground fault over-voltage relay device 5 ₁ Only first OVG breaking time T3 _1. Here, the first OVG breaking time T3 ₁ is set in order to cut off the first breaker 4 ₁ only the first ground fault over-voltage relay device 5 ₁ operation.
The logical sum circuit 134 takes a logical sum of the output signal of the _second delay circuit 132 _{2 and} the output signal of the third delay circuit 132 ₃ .

Second power supply ground fault overcurrent relay device 110 ₂ includes a trip signal generation circuit (not shown) having the same configuration as trip signal generation circuit 130 described above.

The first opposed end ground fault direction relay device 120 ₁ includes a trip signal generation circuit 140 as shown in FIG. 6 in order to generate the _third trip signal S ₃ .
Here, the trip signal generation circuit 140 includes a relay determination circuit 141, first to third delay circuits (timers) 142 _{1 to} 142 ₃ , an AND circuit 143, and an OR circuit 144.

Relay determining circuit 141, a ground fault generated in the own line 1L based on the phase relation of the third zero-phase current magnitude and opposite end zero-phase voltage of the I ₀₃ V _0b and third zero-phase current I ₀₃ When detected, a high level output signal is output.
The first delay circuit 142 ₁ delays the second OVG output signal S _OVG2 inputted from the second ground fault over-voltage relay device 5 ₂ by a third timed coordination time T1 _3. Here, the second ground fault over-voltage relay device 5 _2, the high level when the magnitude of the second opposing end zero-phase voltage V _0b inputted from earth type potential transformer 2 ₂ becomes equal to or higher than set point The second OVG output signal S _OVG2 is output. Further, the first time cooperation time T1 ₁ (for example, 800 ms) set in the second delay circuit 132 ₂ shown in FIG. 5 is the third time cooperation time T1 ₃ (for example, 400 ms) for the time cooperation. (T1 ₁ > T1 ₃ ).
The logical product circuit 143 calculates the logical product of the output signal of the relay determination circuit 141 and the second OVG output signal S _OVG2 delayed by the _first delay circuit 142 ₁ by the third time cooperation time T1 ₃ .
The second delay circuit 142 ₂ delays the output signal of the AND circuit 143 by the third zero-phase free vibration malfunction prevention time T2 ₃ . In addition, the operation time limit T _DG1 of the first opposite-end ground fault direction relay device 120 ₁ is the total time of the third time cooperation time T1 ₃ and the third zero-phase free vibration malfunction prevention time T2 ₃ (T _DG1 = T1 ₃ + T2 ₃ ).
The third delay circuit 142 ₃ delays the second OVG output signal S _OVG2 inputted from the second ground fault over-voltage relay device 5 ₂ by a third OVG interruption time T3 _3. Here, the third OVG breaking time T3 ₃ is set in order to block the third breaker 4 ₃ at only the second ground fault over-voltage relay device 5 ₂ operation.
OR circuit 144 takes the logical sum of the second delay circuit 142 and _second output signal and the third delay circuit 142 ₃ of the output signal.

The second opposite-end ground fault direction relay device 120 ₂ includes a trip signal generation circuit (not shown) having the same configuration as the trip signal generation circuit 140 described above.

When ground fault at a time t ₀ shown in FIG. 7 has occurred in the own line 1L, which is the first power supply terminal land fault overcurrent relay device 110 ₁ of the guard interval, the fault current (zero-phase current I ₀₎ FIG. 4 flows toward the accident point as indicated by a broken arrow, and therefore _first to _fourth zero-phase currents I _{01 to} I ₀₄ flowing through the first to fourth zero-phase current transformers 3 _{1 to} 3 ₄ , respectively. The direction of is the direction indicated by the arrow in FIG. As a result, the first and second power source ground fault overcurrent relay devices 110 ₁ , 110 ₂ operate, and the direction of the third zero-phase current I ₀₃ is the same as the operation direction (internal direction). opposite end ground fault direction relay device 120 ₁ is operated.

Since the operation time limit T _DG1 of the first opposing ground fault direction relay device 120 ₁ is shorter than the operation time _limits T _OCG1 and T _OCG2 of the first and second power source ground fault overcurrent relay devices 110 ₁ and 110 _2. First, the first opposing ground fault direction relay device 120 ₁ operates to interrupt the third circuit breaker 4 ₃ installed on the opposing end side of the own line 1L. At this time, as shown in FIG. 7, the third circuit breaker 4 ₃ includes the relay determination time T _RY (50 ms) and the operation time limit T _DG1 (= T 1 ₃ ) of the first opposing ground fault direction relay device 120 _1. (+ T2 ₃ = 400 ms + 100 ms = 500 ms) at time t ₂ , which is blocked by the _third trip signal S ₃ output from the first opposite-end ground fault direction relay device 120 _1, but the third cutoff the vessels 4 ₃ is completely cut off, the time t ₃ when the circuit breaker interruption time T _CB (50 ms) has elapsed from the time t _2.

When the third circuit breaker 4 ₃ is completely cut off at the time t ₃ , the fault current flows only from the power supply end of the own line 1L toward the fault point (ie, the first zero as shown in FIG. 7). Since only the phase current I ₀₁ flows), only the first power source ground fault overcurrent relay device 110 ₁ continues to operate and shuts off the first circuit breaker 4 ₁ installed on the power source side of the own line 1L. To do. At this time, the first circuit breaker 4 ₁ is connected to the relay determination time T _RY (50 ms) and the operation time limit T _OCG1 (= T1 ₁ + T2) of the first power supply ground fault overcurrent relay device 110 ₁ from the accident occurrence time t ₀ . ₁ = 800 ms + 100 ms = 900 ms), but the first circuit breaker is completely interrupted by the _first trip signal S ₁ output from the first power source ground fault overcurrent relay device 110 ₁ at time t ₄ when elapses. 4 ₁ is completely cut off at time t ₅ when the circuit breaker breaking time T _CB (50 ms) has elapsed from time t ₄ .

The following Patent Document 1 discloses a ground fault having high reliability that can be surely interrupted regardless of the magnitude of the fault point resistance at the time of a ground fault and can be easily applied to two or more multi-line transmission lines. A line selection protection relay device is disclosed. In this ground fault line selection protection relay device, the line zero-phase current detected by the current detector is supplied to the ratio calculation circuit via the converter. The neutral point zero-phase current detected by the current detector is supplied to the ratio calculation circuit via the input converter. In the ratio calculation circuit, the ratio of the line zero-phase current and the neutral point zero-phase current is calculated and supplied to the accident detection circuit to determine whether or not it is greater than 1 / number of lines. When the ratio is large, it is determined that a ground fault has occurred, and a determination signal is supplied from the detection circuit to the determination output circuit. The determination output circuit supplies a break signal to the breaker, and line 1 is separated from the bus. Since the ratio does not include the fault point resistance value, a ground fault is reliably detected without being affected by this resistance value.
Further, the applicant in Patent Document 2 below, in order to enable a reduction in the power failure range when an accident occurs in parallel receiving mode while enabling operation at the same facility regardless receiving mode, the current I ₁ the sum current relay element that operates over current of the current sum of I _2, the current I _1, and each individual Tsugiden elements operating in overcurrent I _2, the sum current relay element operation when the busbar breaker " ”On” to confirm that the bus line breaker is opened immediately and the operation of each individual relay element to confirm that the bus line breaker or sound line breaker is “open”. It has proposed a composite power receiving bus protection relay device that can open the fault circuit breaker in both cases of parallel power reception and individual power reception by having a sequence function to be opened.
JP-A-5-328588 JP-A-11-206006

However, in the first power supply ground fault overcurrent relay device 110 ₁ described above, when a ground fault occurs in the own line 1L, the first circuit breaker 4 ₁ detects the relay determination time T ₀ from the fault occurrence time t _{0. Since} it is shut off at time t ₅ when the total time of _RY , operation time limit T _OCG1 and circuit breaker breaking time T _CB has elapsed (see Fig. 7), it takes time (about 1 s) to eliminate this ground fault. There is a problem of adversely affecting the equipment.

In addition, the operation time limit T _OCG1 may be increased due to operational restrictions when the neutral point compensation reactor (NGL) of the zero-phase power supply behind the opposite-end bus is large or when the system is changed. When a ground fault occurs at 1L, there is a problem that the accident removal time is further increased and the facilities are adversely affected.

  It is an object of the present invention to provide a ground fault overcurrent relay device for a power supply terminal that can greatly reduce the accident removal time.

The ground fault overcurrent relay device of the present invention is a balanced two-line power transmission line composed of a self-line (1L) and another line (2L) laid between a power source side bus and a counter end bus on the opposite end side. A ground fault overcurrent relay device (10 ₁ ) installed on the power supply end side of the own line, and detecting a ground fault occurrence on the own line, the own line provided on the power supply end side of the own line A trip signal generation circuit (20) for generating a trip signal (S ₁ ) for breaking the circuit breaker (4 ₁ ) is provided, and the trip signal generation circuit is directed from the power supply terminal of the own line toward the accident point. The difference between the own line zero-phase current (I ₀₁ ) flowing and the other line zero-phase current (I ₀₂ ) flowing from the power supply terminal of the other line toward the fault point, the own line zero-phase current and the other line zero-phase current If a ground fault is detected based on the ratio to the sum of Characterized in that it comprises a trip signal generating means for generating a trip signal.
Here, the trip signal generating means, the other line of the installed adjacent line circuit breaker to the power supply terminal side (4 ₂₎ provided that the is not interrupted, ground fault in the self-line on the basis of the ratio When the occurrence of an accident is detected, the trip signal may be generated by shortening the operation time limit.
The trip signal generating means obtains a value obtained by dividing the difference between the self-line zero-phase current and the other-line zero-phase current by the sum of the self-line zero-phase current and the other-line zero-phase current. A self-line accident determination circuit (25) that outputs an output signal when the value is greater than or equal to a determination value, and an output signal of the self-line accident determination circuit and a contact signal (S _C2 ) input from the adjacent line breaker And a logical product circuit (23 ₃ ) that takes a logical product.
When the own line fault determination circuit has a zero-phase power source behind the opposite-end bus, the ratio between the zero-phase power source capacity behind the opposite end and the zero-phase power source capacity behind the power source terminal is “k”. A value obtained by dividing the difference between the self-line zero-phase current and the other-line zero-phase current by the sum of the self-line zero-phase current and the other-line zero-phase current and further dividing by “1 + k”; An output signal may be output when the obtained value is equal to or greater than the determination value.
The determination value may be set to “1-X / 100” when an X% section from the power supply end to the opposite end of the own line is set as a time-reduced protection section.
The time-limited shortening protection section may be a section of 80 to 85% from the power supply end to the opposite end of the own line.
The other ground fault overcurrent relay device (10 ₂ ) installed on the power supply end side of the other line may have the same configuration as that of the ground fault overcurrent relay device and may be integrally configured.

The ground fault overcurrent relay device of the present invention has the following effects.
(1) A ground fault overcurrent relay installed on the power supply end side of a balanced two-line transmission line has its own line zero-phase current flowing from the power supply end of the own line toward the fault point and the fault point from the power supply end of the other line. If a ground fault is detected based on the ratio of the difference between the zero-phase current of the other line flowing toward the sum of the zero-phase current of the own line and the zero-phase current of the other line, a trip signal is generated by shortening the operation time limit. The removal time of ground faults occurring on the own line can be greatly shortened.
(2) Since the accident continuation time is also greatly shortened, adverse effects on the equipment at the time of the accident can be reduced.
(3) Since it is possible to omit the main protection relay device, the investment cost to the facility can be reduced.
(4) Although only the difference between the zero-phase current of the own line and the zero-phase current of the other line is affected by the change in the zero-phase power supply capacity behind the power supply end, By using the ratio between the zero-phase current and the sum of the zero-phase currents of the other lines, it is possible to determine the own line fault without being affected by the change in the zero-phase power source capacity behind the power supply end.
(5) If there is a power supply behind the opposite end, a ground fault can be made without changing the detection sensitivity by considering the ratio of the zero-phase power supply capacity behind the opposite end and the zero-phase power supply capacity behind the power supply end. Can be removed.

  For the above purpose, the ground fault overcurrent relay installed on the power line end of the own line is directed to the self-line zero-phase current flowing from the power line end of the own line toward the fault point and from the power line end of the other line to the fault point. When a ground fault is detected based on the ratio of the zero-phase current flowing through the other line, the trip time is generated by shortening the operation time limit.

Embodiments of the ground fault overcurrent relay device of the present invention will be described below with reference to the drawings.
The ground fault overcurrent relay device of the present invention is a ground fault overcurrent relay device installed on the power supply end side of the balanced two-line transmission line, and when a ground fault occurs, the fault line is connected to the power source end of the balanced two-line transmission line. Pay attention to the fact that the ratio of the fault current (first zero-phase current I ₀₁ ) is larger than the ratio of the fault current (second zero-phase current I ₀₂ ) of the healthy line. And the ratio of the difference between the fault line fault current and the fault line fault current to the sum of the fault line fault current and the fault line fault current (the value obtained by dividing the former by the latter). Then, the trip time is generated by shortening the operation time period.

Accordingly, the first power supply ground fault overcurrent relay device 10 ₁ (ground fault overcurrent relay device according to one embodiment of the present invention) shown in FIG. 1 is installed on the power supply end side of the other line 2L which is a healthy line. and second circuit breakers 4 ₂ is not blocked, and, upon detecting a ground fault generated in its own line 1L with accident circuits based on the own line accident determination condition shown in (1), first at opposite ends ground direction relay device 120 _first operating time period T _DG1 first self line accident determining lockout time T4 ₁ which is settled to be shorter than the ability to generate the first trip signals S ₁ This is different from the conventional first power supply ground fault overcurrent relay device 110 _{1 shown} in FIG.
(I ₀₁ −I ₀₂ ) / (I ₀₁ + I ₀₂ ) ≧ 0.2 (1)
Here, the determination value is timed shortened GI (i.e., a first range of its own line 1L to generate the first trip signals S ₁ by the own line accident determining lockout time T4 ₁ with respect to earth fault) If the determined X% section from the power supply end of the own line 1L to the opposite end is set as the time-reduced protection section, the determination value = 1−X / 100. Therefore, the determination value (= 0.2) in the expression (1) is used when the 80% section from the power supply end to the opposite end of the own line 1L is used as the time-reduced protection section. Note that the time reduction protection section requires a margin of about 15 to 20% in consideration of errors such as current transformer errors (CT errors), relay errors, and line constant errors. The section is 80 to 85% up to the opposite end.
The first self-line accident determining lockout time T4 ₁ is basically (set to about 100 ms) set in the first zero-phase free vibration lockout time T2 ₁ and the same purpose, It also includes a function to prevent instantaneous changes when determining own line accidents.

That is, the first power supply terminal land fault overcurrent relay device 10 _1, the second contact signal S _C2 input from the second circuit breaker 4 ₂ is at high level (second circuit breaker 4 ₂ blocking by showing that no.), and a second input the first zero-phase current I ₀₁ from the second zero-phase current transformer 3 ₂ input from the first zero-phase current transformer 3 ₁ The value obtained by dividing the difference from the zero-phase current I ₀₂ (= I ₀₁ −I ₀₂ ) by the first zero-phase current I ₀₁ , the second zero-phase current I ₀₂ and the sum (I ₀₁ + I ₀₂ ) On the condition that (= 0.2) or more, the first trip signal S ₁ is generated during the first own line fault determination malfunction prevention time T 4 ₁ .
To achieve this, the first power supply terminal land fault overcurrent relay device 10 _1, instead of the trip signal generating circuit 120 shown in FIG. 5, comprises a trip signal generating circuit 20 shown in FIG.

As shown in FIG. 2, the trip signal generation circuit 20 includes a relay determination circuit 21, first to fourth delay circuits (timers) 22 _{1 to} 22 _4, and _first to third AND circuits 23 ₁ to 23 ₁ . 23 ₃ , an OR circuit 24, and a local line fault determination circuit 25.

Similar to the relay determination circuit 131 shown in FIG. 5, when the relay determination circuit 21 detects a ground fault that has occurred in the own line 1L based on the magnitude of the first zero-phase current I ₀₁ , the relay determination circuit 21 outputs a high level. Output a signal.
The first delay circuit 22 _1, similar to the first delay circuit 132 ₁ shown in FIG. 5, delays the first OVG output signal S _OVG1 by a first timed coordination time T1 _1.
Similarly to the logical product circuit 133 shown in FIG. 5, the first logical product circuit 23 ₁ is delayed by the first time cooperation time T1 ₁ by the output signal of the relay determination circuit 21 and the first delay circuit 22 ₁ . The logical product with the first OVG output signal S _OVG1 is obtained.
Similarly to the _second delay circuit 132 ₂ shown in FIG. 5, the second delay circuit 22 ₂ outputs the output signal of the first AND circuit 23 ₁ for the first zero-phase free vibration malfunction prevention time T2 _1. Delay.
Similar to the _third delay circuit 132 ₃ shown in FIG. 5, the third delay circuit 22 ₃ delays the first OVG output signal S _OVG1 by the first OVG cutoff time T3 ₁ .
The second AND circuit 23 ₂ performs the first trip when a ground fault is not detected in the relay determination circuit 21 (when the first power source ground fault overcurrent relay device 10 ₁ is not operating). is intended so that the signal S ₁ is not output in the first self-line accident determining lockout time T4 ₁ by mistake, the output signal of the relay determining circuit 21 and the logic of the first OVG output signal S _OVG1 Take the product.
Own line accident determining circuit 25, a first difference between the zero-phase current I ₀₁ and the second zero-phase current _{I 02 (= I 01 -I 02} ) and the first zero-phase current I ₀₁ second zero A value obtained by dividing the phase current I ₀₂ by the sum (I ₀₁ + I ₀₂ ) is obtained, and if the obtained value is equal to or greater than the determination value (= 0.2), a high-level output signal is output.
The third AND circuit 23 ₃ takes the logical product of the output signal of the _second AND circuit 23 ₂ , the output signal of the own line fault determination circuit 25, and the second contact signal S _C2 .
The fourth delay circuit 22 ₄ delays the output signal of the _third AND circuit 23 _{3 by} a first malfunction prevention time T4 ₁ at the time of the own line fault determination.
The logical sum circuit 24 takes a logical sum of the output signal of the _second delay circuit 22 ₂ , the output signal of the third delay circuit 22 ₃ , and the output signal of the fourth delay circuit 22 ₄ .

  Next, the operation of the trip signal generation circuit 20 when a ground fault occurs in the own line 1L shown in FIG. 1 will be described with reference to FIG.

When a ground fault occurs at time t ₀ in the own line 1L, the _first to _fourth zero-phase currents flowing through the first to fourth zero-phase current transformers 3 _{1 to} 3 ₄ as described with reference to FIG. The directions of I _{01 to} I ₀₄ are the directions indicated by arrows in FIG. As a result, the first and second power source ground fault overcurrent relay devices 10 ₁ and 10 ₂ operate, and the direction of the third zero-phase current I ₀₃ is the same as the operation direction (internal direction). opposite end ground fault direction relay device 120 ₁ is operated.

Accordingly, the relay determining circuit 21 of the trip signal generating circuit 20 to the first power supply terminal land fault overcurrent relay device 10 ₁ comprises the ground fault in the self line 1L based on the first zero-phase current I ₀₁ is generated A high level output signal is output. First ground fault over-voltage relay device 5 _1, the magnitude of the power supply terminal zero-phase voltage V _0a is at setpoint above, outputs the first OVG output signal S _OVG1 high level. As a result, the output signal of the _second AND circuit 23 ₂ changes from the low level to the high level.
Further, the difference (= I ₀₁ -I ₀₂₎ and the first zero-phase current I ₀₁ second zero-phase current I ₀₂ of the first zero-phase current I ₀₁ and the second zero-phase current I ₀₂ OR If the value divided by (I ₀₁ + I ₀₂ ) is equal to or greater than the determination value (= 0.2), the own line accident determination circuit 25 determines that a ground fault has occurred in the own line 1L, and the high level Output the output signal.
As a result, when the second contact signal S _C2 input from the second circuit breaker 4 ₂ is at a high level, the output signal of the _third AND circuit 23 ₃ is changed from a low level to a high level.

The high-level output signal of the _third AND circuit 23 ₃ is delayed by the first own line fault determination malfunction prevention time T 4 ₁ by the fourth delay circuit 22 ₄ and then input to the OR circuit 24. The As a result, the output signal of the OR circuit 24 changes from the low level to the high level.
As a result, the high-level first trip signal S ₁ changes from the accident occurrence time t ₀ to the first power source ground fault overcurrent relay device 10 ₁ , the relay determination time T _RY (50 ms), and the fourth time limit coordination time. After the total time of T4 ₁ (100 ms) (= 50 ms + 100 ms = 150 ms) has elapsed, it is output from the trip signal generation circuit 20 to the first circuit breaker 4 ₁ .

At this time, also in the first opposing end ground fault direction relay device 120 ₁ , as described with reference to FIGS. 6 and 7, the second opposing end ground fault direction relay device from the accident occurrence time t ₀ . The third trip signal S ₃ at the high level becomes the third circuit breaker at the time t ₂ when the total time of the relay determination time T _RY (50 ms) 120 ₂ and the operation time limit T _DG1 (= 50 ms + 400 ms + 100 ms = 550 ms) has elapsed. 4 is outputted to _3, the first self-line accident determining lockout time T4 ₁ (100 ms) is shorter settling than the second operation of the opposite end ground fault direction relay device 120 ₂ timed T _DG1 (500 ms) Therefore, the high-level first trip signal S ₁ is output at time t _1a earlier than time t ₂ as shown in FIG.

Accordingly, the first circuit breaker 4 ₁ is completely cut off at time t _1b , which is earlier than the third circuit breaker 4 _3, by the circuit breaker cut-off time T _CB (50 ms) from time t _1a . As a result, compared with the case of the conventional first power supply ground fault overcurrent relay device 110 ₁ shown by a broken line in FIG. 3 (see FIG. 7), the first circuit breaker 4 ₁ is t ₅ −t _1b = It is possible to shut off earlier by T _{OCG1 −T4 1} (= 900 ms−100 ms = 800 ms).

When the first circuit breaker 4 ₁ is completely cut off, the fault current flows only from the power supply end of the other line 2L toward the fault point, so that the first opposing ground fault direction relay device 120 ₁ operates. Subsequently, the third circuit breaker 4 ₃ is completely cut off at time t ₃ when the circuit breaker breaking time T _CB (50 ms) has elapsed from time t ₂ . Therefore, the third circuit breaker 4 ₃ is completely cut off at the same time t ₃ as in the conventional case shown in FIG.

The second power supply ground fault overcurrent relay device 10 ₂ is configured in the same manner as the first power supply ground fault overcurrent relay device 10 ₁ , so that when a ground fault occurs in the other line 2L, a second circuit breaker 4 ₂ can be shut off as soon as T _OCG2 -T4 ₂ than the second power supply terminal locations fault overcurrent relay device 110 _2. Here, T _OCG2 is the second operation timing of the power supply terminal land fault overcurrent relay device 10 _2, T4 ₂ is trip signal generating circuit _{(Figure 2} a second power supply terminal land fault overcurrent relay device 10 comprises 2 is a second delay circuit set in the fourth delay circuit of FIG. 2), and the malfunction prevention time at the time of second own line fault determination.

If there is a zero-phase power source behind the opposite end (behind the opposite end bus), the zero-phase power capacity (opposite end bus) behind the opposite end is substituted for the own line fault judgment condition shown in equation (1). The ratio k between the zero-phase power supply capacity at the back and the zero-phase power supply capacity at the back of the power supply terminal (the zero-phase power supply capacity behind the bus) (zero-phase power supply capacity = neutral grounding resistance (NGR) + neutral point compensating reactor ( By using the own line accident determination condition shown in the equation (2) considering NGL)), the ground fault can be eliminated without changing the detection sensitivity.
(I ₀₁ −I ₀₂ ) / (I ₀₁ + I ₀₂ ) / (1 + k) ≧ 0.2 (2)
Here, k = (zero phase power capacity behind the opposite end) / (zero phase power capacity behind the power end)
In this case, the own line fault determination circuit 25 shown in FIG. 2 calculates the difference (= I ₀₁ −I ₀₂ ) between the first zero-phase current I ₀₁ and the second zero-phase current I ₀₂ as the first A value obtained by further dividing the value obtained by dividing the zero-phase current I ₀₁ , the second zero-phase current I ₀₂ and the sum (I ₀₁ + I ₀₂ ) by “1 + k” is obtained, and the obtained value is “0.2” or more. And outputs a high level output signal.

Further, when considering short circuit priority, an inoperative condition of an undervoltage relay device (not shown) connected to the bus may be added. In this case, an inverter circuit for inverting the polarity of the high level undervoltage relay operation signal indicating the operation of the undervoltage relay device is added to the trip signal generation circuit 20 shown in FIG. Are input to the _third AND circuit 23 ₃ , the output signal of the _second AND circuit 23 ₂ , the output signal of the own line fault determination circuit 25, the second contact signal S _C2, and the inverter circuit What is necessary is just to make the _3rd AND circuit 23 ₃ take a logical product with an output signal.

In the above description, the first and second power source ground fault overcurrent relay devices 10 ₁ and 10 ₂ are individually configured, but may be configured integrally.
Further, the delay circuits such as the _{first to} fourth delay circuits 22 _{1 to} 22 ₄ shown in FIG. 2 may be configured by a circuit that delays the input signal by a predetermined time, or the input signal is inputted. And a timer that outputs an output signal after counting a predetermined number of times.

Is a diagram for explaining an embodiment the first power supply terminal land fault overcurrent relay device 10 ₁ is a ground fault overcurrent relay device according to the present invention. First power supply terminal land fault overcurrent relay device 10 ₁ shown in FIG. 1 is a block diagram showing the configuration of a trip signal generation circuit 20 that comprises. It is a figure for demonstrating operation | movement of the trip signal generation circuit 20 shown in FIG. 2 when a ground fault accident generate | occur | produces in the own line 1L shown in FIG. It is a figure for demonstrating that the ground fault overcurrent relay apparatus is used as a backup protection in a balanced two-line transmission line. FIG. 5 is a block diagram showing a configuration of a trip signal generation circuit 130 included in the first power supply ground fault overcurrent relay device 110 ₁ shown in FIG. 4. FIG. 5 is a block diagram illustrating a configuration of a trip signal generation circuit 140 included in the first opposite-end ground fault direction relay device 120 ₁ illustrated in FIG. 4. To explain the operation of _first power supply ground fault overcurrent relay device 110 ₁ and first opposing ground fault direction relay device 120 ₁ shown in FIG. 4 when a ground fault occurs in own line 1L. FIG.

Explanation of symbols

1 power supply 2 _1, 2 ₂ first and second grounding-type instrument transformer 3 ₁ to 3 ₄ first to fourth ZCT 41 _{to 4} first through fourth breakers 5 ₁ , 5 ₂ 1st and 2nd ground fault overvoltage relay devices 10 ₁ , 10 ₂ , 110 ₁ , 110 ₂ 1st and 2nd power supply ground fault overcurrent relay devices 20, 130, 140 Trip signal generating circuit 21 , 131, 141 Relay determination circuits 22 _{1 to} 22 ₄ First to fourth delay circuits 23 ₁ to 2 _{3 1st} to _3rd AND circuits 24, 134, 144 OR circuit 25 Own line fault determination circuit 120 ₁ , 120 ₂ first and second opposite ends ground direction relay device 132 _{1-132 3,} 142 _{1 to 142 3} first to third delay circuits 133 and 143 aND circuits 1L own line 2L other line V _0a Power supply end zero phase voltage V _{0b Opposing} end zero phase voltage I _{01 to} I ₀₄ 1st to 4th zero phase current S ₁ To S ₄ first through fourth trip signal S _OVG1, S _OVG2 first and second OVG output signal S _C1, S _C2 first and second contact signal T1 ₁ to T1 ₄ first to fourth timed Cooperation time T2 _{1 to} T2 ₄ First to fourth zero-phase free vibration malfunction prevention time T3 _{1 to} T3 ₄ First to fourth OVG cut-off times T4 _{1 to} T4 ₄ First to fourth own line fault determination Malfunction prevention time T _OCG1 , T _OCG2 , T _DG1 operation time limit T _RY relay processing time T _CB breaker breaking time t _{0 to} t ₅ , t _1a , t _1b time

Claims (7)

Installed on the power supply end side of the own line of the balanced two-line power transmission line composed of the own line (1L) and the other line (2L) laid between the power supply end side bus line and the opposite end side opposite end bus line A ground fault overcurrent relay device (10 ₁ ),
When the occurrence of a ground fault in the own line is detected, a trip signal generating circuit (S ₁ ) for generating a trip signal (S ₁ ) for breaking the own line breaker (4 ₁ ) provided on the power source end side of the own line ( 20),
The trip signal generation circuit includes a self-line zero-phase current (I ₀₁ ) that flows from the power supply end of the self-line toward the fault point, and another line zero-phase current (I ₀₁ ) that flows from the power supply end of the other line toward the fault point ( Trip signal generating means for generating the trip signal by shortening the operation time period when a ground fault is detected based on the ratio of the difference between I ₀₂ ) and the sum of the zero-phase current of the own line and the zero-phase current of the other line Comprising
A ground fault overcurrent relay device. On the condition that the trip line generating means is not interrupted by the adjacent circuit breaker (4 ₂ ) installed on the power supply end side of the other line, a ground fault in the own line is generated based on the ratio. 2. The ground fault overcurrent relay device according to claim 1, wherein when detected, the trip signal is generated by shortening an operation time limit. The trip signal generating means is
A value obtained by dividing the difference between the self-line zero-phase current and the other-line zero-phase current by the sum of the self-line zero-phase current and the other-line zero-phase current is obtained, and the obtained value is equal to or greater than a determination value. And a self-line accident determination circuit (25) for outputting an output signal;
A logical product circuit (23 ₃ ) that takes the logical product of the output signal of the own line fault determination circuit and the contact signal (S _C2 ) input from the adjacent circuit breaker;
The ground fault overcurrent relay device according to claim 2, comprising:   When the own line fault determination circuit has a zero-phase power source behind the opposite-end bus, the ratio between the zero-phase power source capacity behind the opposite end and the zero-phase power source capacity behind the power source terminal is “k”. A value obtained by dividing the difference between the self-line zero-phase current and the other-line zero-phase current by the sum of the self-line zero-phase current and the other-line zero-phase current and further dividing by “1 + k”; The ground fault overcurrent relay device according to claim 3, wherein an output signal is output when the obtained value is equal to or greater than the determination value.   The determination value is set to "1-X / 100" when a section of X% from the power supply end of the own line to the opposite end is set as a time-reduced protection section. Or the earth fault overcurrent relay apparatus of 4.   6. The ground fault overcurrent relay device according to claim 5, wherein the time-reduced protection section is a section of 80 to 85% from the power supply end to the opposite end of the own line. The other ground fault overcurrent relay device (10 ₂ ) installed on the power supply end side of the other line has the same configuration as that of the ground fault overcurrent relay device and is integrally formed. The ground fault overcurrent relay device according to any one of claims 1 to 6.

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