JPS594925B2 - Constant monitoring method for phase comparison relays - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant monitoring system for a phase comparison relay, and particularly to a constant monitoring system for a phase comparison relay suitable for sending out a continuous trip permission signal when a circuit breaker is opened.

As a protective relay device for an important power transmission line such as the so-called main power transmission line of an electric power system, a high-speed operation, highly reliable carrier protection relay device with excellent protection performance is generally employed.

In particular, ultra-high-voltage and ultra-super-high-voltage power transmission lines are equipped with a phase-comparison transport protection relay device that can apply a multi-phase reclosing method that selectively cuts off only the failed phase and recloses it at high speed.

Such a phase comparison relay is equipped with a constant monitoring circuit that detects and displays an abnormality in the phase comparison relay based on the carrier signal from the other end and the operating status of the phase comparison relay. There is a problem in that it is not possible to detect when the carrier signal indicates trip permission.

The present invention seeks to solve this problem.

The conventional constant monitoring circuit will be explained with reference to FIG. 5, and the constant monitoring circuit of the present invention will be explained with reference to FIG. 6.Before that, the premise of the present invention will be explained with reference to FIGS. 1 to 4.

FIG. 1 shows a power system in which a phase comparison relay 7 is installed, and the phase comparison relay is installed at an electric station A and an electric station B.

Items common to both electrical stations are designated by the same reference numerals.

Reference numeral 1 indicates a busbar, and reference numeral 2 indicates a generator behind the power station. When a fault occurs on the power transmission line, the fault current is supplied from this generator.

The busbars 1 of electric stations A and B are interconnected by a power transmission line 5 via a circuit breaker 4, respectively.

When an accident occurs on the power transmission line 5, the relay side current 6 proportional to the fault current flowing through the power transmission line 5 is guided by the current transformer 3 installed at both electric stations to the phase comparison relay 7, and the output circuit 11 of 7 The circuit breaker 4 is opened.

The current 6 guided to the phase comparison relay γ is converted from a sinusoidal alternating current into a rectangular wave by a rectangular wave shaping circuit 8 inside the phase comparison relay.

The relay side currents 6A and 6B detected at both electric stations have the same polarity when a passing current occurs in the event of an external fault as shown in FIG. 2a.

In a phase comparison relay that is treated as a power supply terminal to an electrical station, a rectangular wave made of a positive half wave that exceeds level LH becomes a trip-permissible phase signal (hereinafter referred to as F2 signal), and other sections are trip-permitted. This becomes a lock phase signal (hereinafter referred to as F1 signal).

In addition, in the phase comparison relay that is treated as a variable power supply at electric station B, the rectangular wave created by the current on the side that includes zero from level LL becomes the F2 signal, contrary to the power supply end, and the other section becomes the F1 signal. becomes.

The phase signal generated by the rectangular wave shaping circuit 8 is guided to the matching circuit 9 (actually, it passes through a circuit that compensates for the transmission delay time until the phase signal transmitted from the other end reaches the matching circuit 9 at the other end). is omitted here for the sake of brevity), and is simultaneously transmitted to the transmitter 13 of the information transmission device 12, and generally further transmitted to the receiver 14 of the other party's information transmission device 12 via the microwave line 15. Ru.

On the other hand, in the same way, the other end phase signal sent from the transmitter 13 of the other end information transmission device 12 through the microwave line 15 passes through the receiver 14 of the information transmission device 12 at the other end, and then passes through the phase comparison relay 7. It is introduced into the other input terminal of the matching circuit 9.

In the matching circuit 9, an AND signal of the F2 signals at both ends is created,
If this magnitude is measured by the next integrating circuit 10 and is large enough to be determined as an internal accident that should be protected, generally 6O-0) or more, the output circuit 11 issues a command to draw out the circuit breaker 4.

Although only one set of phase comparison relays is shown in FIG. 1, in the phase comparison method, each phase comparison relay is installed for each phase of A, B, and C, and the above-mentioned operation is performed independently for each phase.

Next, referring to FIG. 2, the response of the device shown in FIG. 1 to a system accident will be explained.

Components in FIG. 2 that are the same as those in FIG. 1 are designated by the same reference numerals.

Figure 2a shows the response to an accident outside the protected area, and as shown, the accident point F is outside the electrical station B.

Therefore, the current on the relay side of the transformer 3 is A terminal 6A and B terminal 6B.
In this case, both the size and the phase are the same.

The A terminal current, which is treated as the power supply terminal, is converted into a rectangular wave by the slice level LH in the rectangular wave shaping circuit 8 as shown in 8A, and then F2
In other sections, the F1 signal becomes the F1 signal.

The B-terminal current, which is treated as a variable power supply terminal, is converted into a rectangular wave by the slice level LL in the rectangular wave shaping circuit 8, and is converted into an F2 signal as shown in 8B, contrary to the electrical station A, which is treated as a power supply terminal, and the other section is an F1 signal. become.

In the matching circuit 9, the F2 signals of 8A and 8B are ANDed, but as shown in 9 (A, B), the AND output of 9 cannot be obtained.
Therefore, since there is no signal at all in the integrating circuit 10 and the output circuit 11 as shown in 10 (A, B) and 11 (A, B), respectively, no breaker tripping signal is generated.

It is well known that the slice level L at the power supply end is variable and the slice level LL at the source end is configured to be I, H) I, L so that the F2 signals at both ends do not overlap due to an external accident. This is a fact.

Figure 2 shows the case of an internal accident when power is supplied at both ends, and as shown, there is an accident point F on the power transmission line 5 connecting electric station A and electric station B.

Due to an internal accident in the section, contrary to Figure 2a, the currents on the relay side of transformer 3 A terminal 6A and B terminal 6B are almost in opposite phase 8
As shown in A and 8B, a square wave is created at each terminal station,
Since F1 signal and F2 signal are generated, matching circuit 9 (
In A, B), matching outputs as shown in the figure appear, and when this is measured (integrated) by the integrating circuit 10, the slice level SL, which is approximately the same as shown in 10 (A, B), is reached in the output circuit. An output is generated from 11 (A, B), and this signal opens the circuit breaker and eliminates the accident F.

In Figure 2 C, the accident point is inside the protected area, as in Figure 2, but unlike in Figure 2, there is no power source behind electric station B at the variable power source end (generator 2 is missing). Therefore, this is a case where no fault current is supplied from the B terminal.

Therefore, 6A and 8A are exactly the same as shown in FIG.

However, as shown in 6B, the current at the B end is not completely heated, so it is always below the LL level, and as shown in 8B, it is F over the entire section.
2, that is, it becomes a phase signal that allows continuous tripping.

Therefore, the F2 signal of 8A appears as it is in the negative number circuit 9 (A, B), and 10 (A, 'B), 11 (A, B)
It is clear that the breaker disconnection signal is issued.

In other words, the phase comparison relay at one end is treated as a variable power supply end (LL
If the current is below level LL, F2
Since the signal is generated, the circuit breaker can be tripped even if no fault current flows.

Now, FIG. 3 shows the conveyance control circuit.

Reference numeral 16 indicates a normally open contact of an auxiliary relay which is energized by a pallet switch when the breaker contact is opened, and is closed when the breaker is opened.

17 represents an OR gate, and PT represents a signal power source.

When there is a signal from the rectangular wave shaping circuit 8 of the phase comparison relay T to the transmitter 13 of the information transmission device 12, the F2 signal is transmitted to the other end, and when there is no signal to the transmitter 13, the F1 signal is transmitted to the other end.

Therefore, a cutoff command is issued to the breaker, and when the breaker opens, 16 is closed, and a signal is continuously supplied from PT to 13 via 17, so that a continuous F2 signal is transmitted to the other end.

There are various benefits to configuring the transport control circuit in this way, including the elimination of internal accidents during so-called single-end track charging operation, where only the breaker at the variable power supply end is closed. is possible.

If the contact 16 is not used, the phase signal at the variable power supply terminal is a repeated signal of Fl and F2, or a continuous F2 signal when the current is small, but since the breaker is opened at the power supply terminal and the current is zero, there is a continuous F signal and a double signal. .

Since the continuous F1 signal from the power supply terminal does not change before and after the occurrence of an internal fault, it is impossible to remove the internal fault.

When a continuous F2 signal is generated by opening the circuit breaker, the phase comparison relay 7 at the variable power source terminal is always in a positive output state, and the contact 7-a in FIG. 4 is closed.

That is, the breaker is closed at the variable power source end, and the phase comparison relay obtains a repeated signal of Fl and F2 or a continuous F2 signal from the passing current as described above.

On the other hand, what is received from the power source end is a continuous F2 signal due to the opening of the breaker.

Therefore, at the variable power supply end, if the voltage drops due to an internal fault, the undervoltage relay 18 detects this and closes it, so that the tripping coil 19 can be excited.

Note that the phase comparison relay at the power supply end has zero current due to the opening of the breaker, and a continuous F and double signal is obtained.

Therefore, how does the received signal from the variable power supply end change?
Moreover, it will not operate even if an internal accident occurs.

FIG. 4 shows the concept of the cutoff circuit of the phase comparison relay device. 7-a is the contact output of the phase comparison relay 7, and when 7 is operated, 7-a is closed.

18 is the contact output of the undervoltage relay. When an accident occurs in the system, the system voltage drops, so the undervoltage relay that receives the system voltage as input detects this and operates, and 18 closes.

When 19 is excited by the tripping coil of the breaker, the breaker opens.

20 is a pallet switch of a circuit breaker, which closes the circuit when the circuit breaker is closed and opens the circuit when the circuit breaker is opened.

PN is a DC operating bus bar. FIG. 5 shows a conventional example of a constant monitoring circuit for the phase comparison relay 7 in the phase comparison conveyance protection relay device constructed as described above.

First, reference numerals 7a, 7b, and 7c indicate phase comparison relays for each phase, each of which receives phase signals from its own end and the opposite end of its own phase and outputs an operating signal.

26 is a timer provided for each phase.
It is determined that the two signals are continuous signals by, for example, continuing for a time corresponding to one cycle or more, and the signal is output.

Reference numeral 21 denotes an inhibit circuit which compares the outputs of the corresponding timer 26 and the phase comparison relay 7, and outputs when the output is greater than the output at 26 and the output at 7.

Reference numeral 28 denotes an OR circuit, and 29 outputs an output when the input continues for a time equivalent to three cycles or more, for example, to display and notify that an abnormality has occurred in the phase comparison relay.

This monitoring circuit operates as follows.

First, in a state where there is no external accident or accident as shown in FIG. 2a, the phase signal from the other end is a repetition of Fl and F2, and the F2 signal has a length of about half a cycle.

(It is not a continuous F2 signal), so the timer 26 does not output.

The phase comparison relay 7 does not output due to an external fault, and the inhibit circuit 27 does not output.

If the phase comparison relay 7 outputs an output in this state, the inhibit circuit 27 outputs, and if this state continues for three cycles or more, an abnormality display is issued via the timer 29.

The reason why the phase comparison relay I outputs an output is not only an internal abnormality in the relay but also an internal fault in the power transmission line.

In the case of an internal accident, the time from the time when the phase comparison relay 7 at the own end outputs to the time when the breaker at the other end is opened, a continuous F2 signal is transmitted, and the timer 26 at the own end detects that it is a continuous F2 signal. Assuming that T1 is T1, a drive signal continues to be applied to the timer 29 via the inhibit circuit 27 during this period.

Regarding this T1 period, it is impossible to distinguish whether the cause of the inhibit circuit 27 giving an output is due to an internal fault in the power transmission line or an internal abnormality in the relay.

However, the time T when the timer 29 gives the operating output
2 (time equivalent to about 3 cycles) is set longer than T. Therefore, the timer 29 correctly outputs only the occurrence of an internal abnormality in the phase comparison relay 7, and does not output in the event of a transmission line fault.

Next, considering the single-end line charging operation state, as mentioned above, the variable power source end with the breaker closed receives a continuous F2 signal from the power source end with the breaker open, and the inhibit circuit 27 is activated by the timer 26. The timer 29 does not output an indication that there is an abnormality.

When an internal accident occurs or when the phase comparison relay 1 outputs an output due to a device abnormality, the variable power supply terminal continues to receive the F2 signal continuously and no abnormality indication is displayed.

Although no abnormality is displayed when the phase comparison relay 7 outputs an erroneous signal as described above, it does not mean that the breaker is erroneously tripped, as described above with reference to FIG. 4.

On the other hand, regarding the power supply end, the phase comparison relay 7 is not outputting as described above.

At this time, the current flowing through the variable power supply terminal is sufficiently larger than the comparison level LL described in FIG.
If the F2 repeated signal is received, "abnormality" can be correctly displayed as in the case where the circuit breaker at both ends is closed and there is no external accident or accident.

If the current at the variable power supply end is smaller than level LL and the phase comparison relay 1 outputs when the power supply end receives the continuous F2 signal, an abnormality cannot be displayed.

However, even if it cannot be displayed, the power supply end circuit breaker is originally in an open state, so it can be said that there is little actual damage.

Even if the phase comparison relay 7 gives an output by mistake, the fourth
As shown in the figure, if the small car voltage relay 18 is not closed, the tripping coil 19 of the circuit breaker will not be energized by mistake, and in addition, it is already open at the power supply end when one end of the line is in the charging operation state. It merely re-energizes the breaker trip coil.

In this single-end line charging operation state, abnormality indications may not be displayed correctly, but since this operation state is performed by simultaneously opening the three phases at one end, it is necessary to recognize this operating state at both ends and take some countermeasures. be able to.

Since the operation is for a very short time and such operation is rare, it can be said that monitoring itself is unnecessary.

As described above, the conventional monitoring circuit shown in FIG. 5 is capable of correctly detecting an abnormality in the phase comparison relay 7 except for the single-end line charging operation state.

However, it has been found that this is not necessarily satisfactory when actively creating a continuous F2 signal as shown in FIG.

That is, when the signal from the other end becomes a continuous F2 signal due to a transmission error, the inhibit circuit 27 does not output even if an error occurs in the phase comparison relay, making it difficult to detect and display this.

However, it is desirable that the monitoring circuit for actively generating continuous F2 signals can correctly detect and display even continuous F2 signals due to transmission abnormalities.

From the above, in the present invention, not only is it possible to detect an erroneous output due to an internal failure of the phase comparison relay itself and display an abnormality, but also to receive a continuous F2 signal due to a transmission error, and as a result, the phase comparison relay The purpose of the present invention is to provide a constant monitoring method for a phase comparison relay that can detect the output of a phase comparison relay and indicate an abnormality.

In order to achieve this object, the present invention, as shown in one embodiment in FIG. 6, is carried out as follows.

a) The inhibit circuit 27 does not take the logic of the timer 26 and the phase comparison relay 7 of the same phase, but of different phases.

b) The timer 29' is set to, for example, 10 seconds, which is longer than the time required to complete high-speed reclosing.

According to this circuit, when there is no internal accident, timer 2
Since the input of 6 is a repetition of the F1 signal and F2 signal, and the F2 signal is less than one cycle, the timer 26 does not output, and when the phase comparison relay 7 mistakenly continues to give an output in this state, the inhibit circuit 27, OR circuit 2
8. The occurrence of an abnormality can be correctly displayed via the timer 29'.

Next, let us consider that a continuous F2 signal occurs only in the a phase due to a transmission abnormality (it can be said that it is almost impossible for this to occur simultaneously in two or more phases.

), the signal from the opposite end of the a-phase phase comparison relay 7a is a continuous F2 signal, and the signal at its own end is a repeated signal of Fl and F2, so 7a provides a continuous operation output to the inhibit circuit 27a.

At this time, since the timer 26a is still a continuous F2 signal, it naturally outputs it, but its output is the inhibit circuit 2γa.
Since the voltage is not applied to the phase comparison relay 7a1, the inhibit circuit 27at, the OR circuit, and the timer 29' indicate that "abnormality has occurred".

As described above, the monitoring circuit of the present invention not only detects an abnormality inside the phase comparison relay, but also detects a transmission abnormality by blocking the output of the phase comparison relay of a different phase using the output of the timer 26.

Although the present invention cannot detect a transmission abnormality that changes to a continuous F1 signal, another countermeasure is taken against this.

Next, looking at the response when an internal accident occurs, timer 2
The time required to reach the operation 9' is about 10 seconds as described above.

This time is even longer than the time it takes to open the breaker due to an internal accident, pass the no-voltage time for reclosing the circuit, re-close the breaker, and re-close it if necessary. .

Therefore, no matter what the inputs or outputs of the phase comparison relay 7, timer 26, etc. are during this time, the timer 29' will not output any output to indicate the occurrence of an abnormality.

As a result of re-turning the power on, when the fault is removed, such as an arc fault, the gold-phase circuit breaker is closed and the circuit shown in Figure 3 does not result in a continuous F2 signal, so the timer 29'
cannot produce an output without losing its input before its output.

As a result of restarting, if the fault is not eliminated, such as a permanent fault, all phases will be shut off at once (protection for each phase by phase comparison is performed only for the first accident; in the case of restarting, any phase Even if there is an accident, all phases are cut off.

), so timer 26at26bt26c are all continuous F.
Since the input to the timer 29' is lost, the timer 29' does not detect an abnormality.

Finally, regarding the one-end line charging operation, the phase comparison relay 7 at the variable power supply end is in an operating state.

However, in the single-end line charging operation, all circuit breakers at the power supply end are opened, so the timer 26 outputs all outputs, the inhibit circuit 27 does not output, and no abnormality is displayed.

Even if an internal accident occurs, continuous F2 will continue from the power supply end.
The signal is being sent, and the constant monitoring circuit at the variable power supply end does not output an abnormality signal.

On the other hand, at the power supply end, when the phase comparison relay erroneously gives an operating output, it is possible to indicate the presence of an abnormality (the input of the timer whose logic is combined in the inhibit circuit 27 is Fl,
There are two cases: when the signal is a repeating F2 signal) and when it cannot be displayed (when the input of the timer whose logic is combined by the inhibit circuit 27 is a continuous F2 signal).

However, as explained in FIG. 5, even if no abnormality display is displayed on the power supply end side (breaker open) during single-end line charging operation, there is no actual damage.

As described in detail above, the present invention not only detects abnormalities that occur in the phase comparison relay, but also detects continuous F
This can also be detected when there are two signals.

This effect is to prevent the output of the phase comparison relay of the other phase by checking the continuous F2 signal of the own phase, and to prevent the output of the phase comparison relay of the other phase, and to prevent the output of the phase comparison relay of the other phase.
This is achieved by setting the confirmation time longer than the time required to complete the reclosure.

In other words, the present invention focuses on the fact that only some phases of the carriers of the phase comparison transport protection relay device become continuous F2 signals only when an accident occurs or when a transmission abnormality occurs.

In the former case, since the duration is fixed, the timer 29' detects this and prevents an abnormal display; in the latter case, the timer 26 and phase comparison relay 7 of the same phase input continuous F2 signals. By combining the outputs of 7 and 26 of different phases with an inhibit circuit, it is possible to indicate transmission abnormalities.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of a general phase comparison carrier protection relay device, Figure 2 is a diagram showing the concept of waveform shaping at each end of the device in Figure 1, Figure 3 is its carrier control circuit, and Figure 4 is a diagram showing the concept of waveform shaping at each end of the device. 5 is a constant monitoring circuit of a conventional phase comparison relay, and FIG. 6 is a constant monitoring circuit of the present invention. γ... Phase comparison relay, 26, 29'... Timer, 27... Inhibit circuit, 28... OR circuit.

Claims (1)

[Claims] 1. When the current of the transmission line is detected for each phase at each terminal of the transmission line, and the current passing through the transmission line is considered to have the same polarity at each terminal, the phase comparison relay, which is treated as the power supply terminal, detects the current level above the specified current level. Trick is allowed during periods that do not include zero current; a phase signal that prohibits tripping during other periods is sent to the other end, and the phase comparison relay, which is treated as a variable power supply terminal, performs tricks during periods when the current is below a predetermined level and includes zero current. A phase signal that allows tripping and prohibits tripping during other periods is sent to the other end, and the relationship between the phase signal at the own end and the phase signal at the other end is determined, and the trip is controlled for each phase at each end. In a phase comparison relay, an open terminal of a breaker sends a phase signal that allows continuous tripping to the other end, and when the breaker fails to reclose, all phases are cut off at once. A first timer for each phase that outputs when the phase carrier signal is a phase signal that allows continuous tripping, and when there is no output from the first timer and a phase comparison relay for the phase and another phase for this timer outputs. A logic circuit provided for each phase comparison relay of each phase outputs when the output is detected.When the output of the logic circuit is obtained continuously for a predetermined period of time or more, it outputs that there is an abnormality in the phase comparison relay or a carrier signal transmission abnormality. A second timer is added, and the predetermined time of the second timer is set to be a time that is sufficiently longer than the time it takes for the circuit breakers to be controlled to open and close all at once after the accident on the power transmission line is removed. A constant monitoring system for ′Σ phase comparison relays.