JPH0531369B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a ground fault directional relay and its device,
In particular, the present invention relates to this type of relay and its device, which allows coordination of the protective operation of each fault direction relay when a plurality of ground fault direction relays are installed in series on a distribution line.

Conventional technology Ground fault directional relays detect zero-sequence voltage and zero-sequence current in the event of a ground fault, compare the phases of these voltages and currents, and detect whether the fault is connected to the power supply side by a zero-sequence current transformer. This is a relay that determines whether it is the load side or the load side, and performs a protective operation in the event of a ground fault on the load side.

A ground fault directional relay device generally installs several ground fault directional relays in series on a distribution line, detects a ground fault in each section, and immediately disconnects the load side of the distribution line where the fault occurred. A protective operation is performed so as not to affect the healthy section on the power supply side. The conventional protection operation is shown in the third example below.
This will be explained using figures.

Figure 3 is a wiring diagram in which multiple ground fault direction relays are installed on the distribution line, 1 is the transformer on the power supply side, 2 is the bridge or disconnector, 3 is the ground fault direction relay installed on the power supply side, and 4 is the ground fault direction relay installed on the power supply side. , 5, 6, 7, and 8 are the shear disconnectors installed on the distribution line on the distribution line side, and 9, 10, 11, 12, and 13 are the loads of each sheath disconnector 4, 5, 6, 7, and 8. Zero-phase current transformers installed on the side, DGR1, DGR2,
DGR3, DGR4, and DGR5 are ground fault direction relays connected to the zero-phase current transformers 9, 10, 11, 12, and 13, and are installed in series from the power supply side (upper stage) to the load side (lower stage). , the above-mentioned shiya disconnector 4~
Give command to 7 to cut off. 14 is a zero-phase voltage signal generator such as a zero-phase voltage relay, which converts the zero-phase voltage into a pulse-like signal V _p , and sends the signal to the common signal line M,
It is applied in parallel to the ground fault direction relays DGR1 to DGR5 via N.

Next, the operation will be explained. Now, for example, zero-phase current transformer 1
When a ground fault occurs at point E on the load side of No. 1, a zero-sequence current is generated in each zero-sequence current transformer 9 to 11, and a zero-sequence voltage signal V _p is generated from the zero-sequence voltage signal generator 14, It is input to the short-circuit direction relay. Then, the relays DGR1 to DGR3 on the power supply side of the ground fault are about to operate. In this case, only the ground fault directional relay DGR3 on the power supply side closest to the ground fault operates, and the disconnector 6
The operating times of each fault directional relay DGR1 to DGR5 are coordinated to ensure that the power source is disconnected quickly and does not affect the distribution line on the power supply side. This operation time is generally coordinated from the ground fault direction relay DGR3 on the lower stage, taking into account the break time of the break switch.
DGR1 and the sequential operation time are set to 0.2 seconds, 0.5 seconds, and 0.8 seconds, respectively, so that, for example, the ground fault direction relay DGR3 operates to quickly disconnect the line disconnector 6 and disconnect the distribution line below the fault. , the upper ground fault directional relays DGR2 and DGR1 are prevented from operating.

Problem to be solved by the invention The operating time of the ground fault direction relay 3 on the power supply side is
It may be set to a short time such as 0.5 seconds.
In this case, the ground fault direction relay DGR1~ on the distribution line side
DGR5 must be set to successively shorter times than 0.5 seconds, but due to the inertial characteristics of the earth fault direction relay,
There is a minimum time required for the operation time of the disconnector, etc.
There is a limit to the amount of time that can be saved. Particularly in the case of large-capacity distribution lines, there is a problem in that when a four-stage or five-stage configuration is arranged in series as shown in FIG. 3, it is virtually impossible to coordinate the operating times.

Means for solving the problem: A circuit for generating a lock selection signal and a lock signal for each fault direction relay, and a circuit that outputs an output signal when the lock selection signal and lock signal are input at the same time to generate a shear break command signal. It is installed in the prohibition signal generation circuit to prevent the relay from generating a prohibition signal due to the lock signal it generates. Locks the disconnection command signal and operates each fault direction relay.

Embodiment FIG. 1 is an internal wiring diagram of a ground fault direction relay according to an embodiment of the present invention, in which the same symbols as in FIG. 3 indicate the same or equivalent parts, and the explanation will be omitted. FIG. 2 shows a time chart for explaining the operation of FIG. 1. It should be noted that the ground fault direction relay shown in FIG. 1 is installed in parallel on the distribution line as in FIG. 3, and the zero-phase voltage signal is inputted from the common signal lines M and N.

In Figure 1, Z ₁ and Z ₂ are connection terminals connected to the zero-phase current transformer, and the ground fault directional relay DGR in Figure 3.
4 is a terminal connected to the zero-phase current transformer 12. m, n are zero-phase voltage signal terminals connected to the zero-phase voltage signal generator 14 via common signals M, N shown in FIG. 20 is a filter, 21
2 is an amplifier, and 22 is a waveform shaping circuit that shapes the zero-sequence current I ₀ into a rectangular zero-sequence current signal. 23 is a level detection circuit which outputs an output signal when the zero-sequence current I _p is above a certain level. 24 is a first AND circuit which receives a zero-sequence current signal and outputs an output signal when an AND condition is established and the zero-sequence current is above a certain level. A second AND circuit 25 receives the output signal of the first AND circuit 24 and the zero-phase voltage signal V _p , and outputs a shear cutting command signal when both signals are input simultaneously. Reference numeral 26 denotes a timer, which is started by a shear breaker command signal from the second AND circuit 25, energizes a relay 27 after _t2 hours, and cuts off the shear breaker 7 via the relay 27. 28 is a lock signal selection circuit connected to zero-phase voltage signal terminals m and n;
A lock selection signal A shown in the figure is generated. This lock selection signal A becomes an on signal after a certain off time T _a from the rise of the zero-phase voltage signal V _p pulse signal. As shown in FIG. 2, the off-time t _a is set to be longer in the order of the upper ground fault direction relays DGR1 to DGR5. 29 is a prohibition signal generation circuit, and an AND circuit 30 takes an AND condition between the lock selection signal which is the output signal of the lock signal selection circuit 28 and the lock signal inputted from the zero-phase voltage signal terminals m and n, and the AND condition is satisfied. It also includes a waveform shaping circuit 31 that sometimes outputs a prohibition signal (C in FIG. 2), and prohibits output from the second AND circuit 25. 32 is a timer which outputs an output signal for t ₁ hour and t ₂ hours after the output of the second AND circuit 25 is received. 33 is a lock signal generation circuit which generates a common signal by inserting it between the pulses of the zero-phase voltage signal V _p from the zero-phase voltage signal terminals m and n at the time t _b set in each fault direction relay _after one hour t. A lock signal is output to lines M and N.
As shown in Fig. 2, this lock signal is set to be issued to the signal lines M and N sequentially from the upper ground fault direction relay after a fixed time t _b after the pulse signal of the zero-phase voltage signal V _p . be done. P2, P3, and P4 indicate lock signals issued from each fault direction relay DGR2, DGR3, and DGR4. Note that the B signal in FIG. 2 indicates the signal at point b on the output side of the AND circuit 30.

In addition, the lock signal from each fault direction relay is
Since the zero-phase voltage signal is sent to the common signal lines M and N via the zero-phase voltage signal terminals m and n, and a lock signal from a ground fault direction relay other than the relay is accepted, the AND circuit 30 also receives its own lock signal. be done. Therefore, as shown in FIG. 2, each fault direction relay is set so that the relationship between the lock signal and the lock selection signal is such that the AND condition of the AND circuit 30 will not be satisfied with the signal it generates.

Next, the operation will be explained.

Now, if a ground fault occurs at point E' on the load side of the zero-phase current transformer 12 in Fig. 3, the zero-phase current input terminal Z of each fault directional relay DGR1 to DGR4 on the power supply side from the point of occurrence of the fault occurs. A zero-sequence current I _p is input to ₁ and Z ₂ , and a zero-sequence voltage signal V _p is input to zero-sequence voltage input terminals m and n,
If the zero-sequence current I _p is above a certain level, the first
is output from the AND circuit 24 to the second AND circuit 25. This second AND circuit 25 determines the phase of the zero-phase current signal and the zero-phase voltage signal, and when the ground fault is on the load side of the zero-phase current transformer, the AND condition of the second AND circuit 25 is established, a stop signal is issued, and the timers 26 and 32 are energized.
On the other hand, at the same time as the zero-phase voltage signal V _p is applied to each zero-phase voltage terminal m, n, the lock signal selection circuit 28 outputs a lock selection signal A having an off time _{t a} set respectively as shown in FIG. is generated and input to the AND circuit 30 of the prohibition signal generation circuit 29.

The zero-phase voltage signal V _p is also input to this AND circuit 30, but since the lock selection signal A is set so that the AND condition is not satisfied for both signals, no output signal is output. Also, when the AND condition of the second AND circuit is satisfied and a shearing command signal is issued, the timer 32 is energized, and after t ₁ hour, it outputs for t ₂ hours and the ground fault direction relays DGR2 and DGR are activated.
3.DGR4 receives lock signals P2, P3, and P4 from the lock signal generation circuit 33 during this time _t2 , and the zero-phase voltage signal terminals m and n of each fault direction relay.
from there to the common signal lines M and N. Therefore, as shown in FIG. 2, the AND circuit 30 of the ground fault direction relay DGR1 receives the zero-phase voltage signal V _p and the lock P from the ground fault direction relays DGR2, DGR3, and DGR4.
2, P3, P4 and lock selection signal A are added,
The lock selection signal A and the lock signals P2, P3, P
4, the AND condition is satisfied, and B is at point b on the output side.
A signal is generated.

When the AND condition with the first lock signal P2 is established, the waveform shaping circuit 31 generates the prohibition signal C, which gives an output prohibition signal to the second AND circuit 25, prohibiting the output of the shunt command signal and causing a ground fault. Locks the output of directional relay DGR1.

Next, the ground fault directional relay DGR2 is activated by the lock selection signal A and the lock signals P3 and P4 when an AND condition is established, and when the AND condition with P3 is established, the prohibition signal generating circuit 29 outputs a signal from the second AND circuit as described above. 2
5 is given a prohibition signal C, and this ground fault direction relay
DGR2 is also locked. Similarly, ground fault directional relay
DGR3 is also locked as described above by forming an AND circuit with lock signal P4. However, the ground fault direction relay
Since the lock selection signal A of the DGR 4 does not meet the AND condition with any of the lock signals, the lock is not applied, and the timer 26 operates when _t2 hours have elapsed since the cut-off command signal was generated. Turn off the disconnect switch 7 and disconnect the faulty distribution line from the power source.

Next, if a ground fault occurs at point E in Figure 3, the ground fault directional relay DGR4 will not generate a disconnection command signal because the fault is on the power supply side, so the lock signal P4 in Figure 2 will be activated. Therefore, the ground fault direction relay DGR3 is not locked, so that the relay DGR3 is operated and the ground fault direction relay DGR3 is operated to disconnect the ground fault breaker 6 _t2 hours after the generation of the shear break command signal.

After ₂ hours have elapsed, the timer 32 stops outputting, so no lock signal is generated, and each fault direction relay that was locked until then is unlocked and ready for the next accident.

Note that the reason why there is no lock signal _P1 in FIG. 2 is that the lock signal generation circuit is omitted for the highest level DGR1 since there is no higher level, and the lock selection signal A is not provided for the lowest level DGR5.
The reason why there is no lock signal selection circuit is because the lowest DGR5 does not need to be locked.

Next, backup protection will be explained.

In the above example, a ground fault occurred at point E' on the load side of the zero-phase current transformer 12, and even though the ground fault direction relay DGR4 operated, for some reason relay 27
If the disconnection signal is not output or if the disconnection signal is output and disconnector 7 does not disconnect immediately, after a certain period of time, the next upper ground fault direction relay DGR3 is operated and the relay is connected to the power supply side. impact must be kept to a minimum.

Reference numeral 40 in FIG. 1 is a backup protection circuit in preparation for such a situation, and a lock signal circuit prohibition circuit 41 is provided to stop the lock signal generation circuit 33 from generating a lock signal using the output signal of the timer 26. In addition,
The timer 32 may be controlled as a means for stopping the generation of the lock signal.

Now, in the above example, if the shield breaker 7 is not disconnected immediately, the earth fault direction relays DGR1 to DGR4 will all be locked by the timer 32 after time _t2 in FIG. The signal disappears, the lock is released, and the system returns to its original state, but since the ground fault continues, an output signal is output from the second AND circuit 25 again, and the same operation is repeated from the left side of Figure 2. . However, the backup protection circuit 40
If the signal from the timer 26 is provided, the signal from the timer 26 will be sent to the ground fault directional relay closest to the ground fault as shown in Figure 2.
Since only DGR4 is present, the lock signal P4 of the relay DGR4 is inhibited by the lock signal prohibition circuit 41 and will not be output during the next operation after returning to the original state, so the B signal of the earth fault direction relay DGR3 will not be generated. The DGR 3 operates, disconnects the shield breaker 6, and performs backup protection.

In the conventional example mentioned above, backup protection can be performed within the range where time coordination can be achieved, but when the number of stages is large and time coordination cannot be achieved as in the present invention, the conventional method can be used. Unable to perform backup protection. In the present invention, even if there are many stages, it is possible to disconnect only the next upper stage relay as described above, so in the above example, the protection zone of the earth fault directional relays DGR2 and DGR1 is not affected. ideal backup protection.

Effects of the Invention As described above, the present invention uses an electric signal to operate only the ground fault relay on the power supply side closest to the ground fault, and all the ground fault relays on the upper stage are locked. As there is no need to coordinate the operating times of multiple stages of ground fault relays from the lower stage to the upper stage, even if the operating time of the ground fault direction relay on the power supply side is set to 0.5 seconds or less. It is also possible to install multi-stage ground fault directional relays.

Furthermore, even if the number of stages increases, ideal backup protection can be achieved.

Further, since the transmission and reception of the lock signal between the respective fault direction relays utilizes a common signal line that originally exists as a zero-phase voltage signal line, there is no need to take the trouble to provide a signal line for the lock signal. Therefore, new costs such as the cost required for the signal line and the facility construction cost for the signal line are not required.

[Brief explanation of the drawing]

FIG. 1 is an internal wiring diagram of a ground fault directional relay of the present invention, FIG. 2 is a time chart for explaining the operation of FIG. 1, and FIG. 3 is a wiring diagram of the ground fault directional relay. In the figure, DGR1 to DGR5 are ground fault direction relays, 20 is a filter, 21 is an amplifier, 22 is a waveform shaping circuit, 23 is a level detection circuit, and 24 is a first
25 is a second AND circuit, 26,
32 is a timer, 28 is a lock signal selection circuit, 2
Reference numeral 9 represents an inhibit signal generation circuit, 33 represents a lock signal generation circuit, and 40 represents a backup protection circuit.

Claims (1)

[Scope of Claims] 1. A zero-sequence voltage signal detected from a power distribution line is received from a common signal line, and this zero-sequence voltage signal and a zero-sequence current signal of a zero-sequence current transformer are connected to a zero-sequence voltage signal terminal and a connection terminal. The ground fault direction relay is configured to determine the direction of the ground fault by comparing the phases of these two signals, and to issue a sag command signal when the ground fault is on the load side. A lock signal selection circuit that generates a lock selection signal that becomes an on signal after a predetermined off time in synchronization with the voltage signal when the signal is input to the zero-phase voltage terminal; a lock signal generating circuit that generates a pulse-like lock signal between the zero-sequence voltage signals for a period of time and sends it from the zero-sequence voltage signal terminal to another ground fault direction relay via the common signal line; The output side of the lock signal selection circuit is connected to the zero-sequence voltage signal terminal, and the ON signal of the lock selection signal and the lock signal from another ground fault direction relay input from the zero-sequence voltage signal terminal are simultaneously input. 1. A ground fault directional relay comprising: a prohibition signal generation circuit that sometimes outputs an output signal to prohibit generation of the shear break command signal. 2 A plurality of ground fault direction relays are installed from the upper stage on the power supply side to the lower stage on the load side of the distribution line, and the zero-sequence voltage signal and zero-sequence current signal detected from the distribution line are applied to each of these fault direction relays. In a ground fault direction relay device that determines the direction of a ground fault by comparing the phases of both signals and issues a shrunken command signal to perform a protective operation when a ground fault occurs on the load side, A phase voltage signal is applied as a pulse signal in parallel to each of the above-mentioned fault direction relays from a common signal line, and when the above-mentioned zero-phase voltage signal is generated in each fault direction relay, a constant width signal is applied in synchronization with the voltage signal. a circuit that generates a lock selection signal; a circuit that generates a pulsed lock signal between the pulses of the zero-phase voltage signal for a certain period of time according to the shearing command signal and sends it to a common signal line; , a prohibition signal generating circuit is provided which outputs an output signal to prohibit the generation of the shedding command signal when these lock selection signals and a lock signal other than the lock signal inputted from a common signal line are input at the same time, The lock selection signal is set to have a longer off time from the zero-sequence voltage signal from the upper ground fault relay to the lower one, and the lock selection signal is sequentially set to the zero-phase voltage signal from the upper ground fault relay to the lower ground fault relay. The lock selection signal and the lock signal are set between pulses so that the lock selection signal and the lock signal are not input to the prohibition signal generation circuit at the same time, and only the earth fault direction relay on the power supply side closest to the ground fault is activated, and the relay on the upper stage is A ground fault directional relay device characterized by locking the operation of a ground fault directional relay. 3 A plurality of ground fault direction relays are installed from the upper stage on the power supply side to the lower stage on the load side of the distribution line, and the zero-sequence voltage signal and zero-sequence current signal detected from the distribution line are applied to each of these fault direction relays. The direction of the ground fault is determined by comparing the phases of both signals, and when the ground fault occurs on the load side, a shunt breaker command signal is sent to the timer, and after a certain period of time, the shunt breaker is shut off to perform a protective operation. In the ground fault direction relay device, the zero-sequence voltage signal is applied in parallel as a pulse-like signal to each of the fault direction relays from a common signal line, and the zero-sequence voltage signal is applied to each fault direction relay in parallel. a circuit that generates a lock selection signal of a constant width in synchronization with the voltage signal when a voltage signal occurs; and a circuit that generates a lock selection signal of a constant width in synchronization with the voltage signal; A circuit that generates a signal and sends it to a common signal line, and when these lock selection signals and a lock signal other than the lock input from the common signal line are input at the same time, outputs an output signal and sends the above-mentioned shedding command signal. a prohibition signal generation circuit that prohibits the generation of the lock selection signal from the upper ground fault direction relay to the lower stage, and sets a longer off time from the zero-phase voltage signal in sequence from the upper stage ground fault direction relay, and The signals are sequentially inserted between the pulses of the zero-phase voltage signal starting from the lower stage of the directional relay, and set so that the own lock selection signal and the lock signal are not input to the prohibition signal generation circuit at the same time. A ground fault directional relay device comprising a backup protection circuit that stops the lock signal of the lock signal generation circuit in response to an output signal.