JPS6070923A - Protecting relaying device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a protective relay device that protects an electric power system, and in particular, to a protection relay device that improves reliability by making it possible to reliably eliminate accidents in the event of a system accident. Regarding relay devices.

[Technical background of the invention and its problems]

Conventionally, various types of protective relays have been used to protect power systems, but distance relays are often used because they are easy to apply to power systems and can provide reliable protection. This distance relay detects faults by introducing the phase voltage and phase current or line voltage and line current of the power system, measuring the line impedance to the fault point, and determining the distance and direction. It is something.

By the way, in a protective relay device using this distance relay, an unnecessary response may occur not only due to a system failure but also due to a loss of synchronization. In other words, if synchronization occurs, the power phases between the generators will not be synchronized, and each generator will operate at its own rotation speed, and the voltage phases between the generators may be in the same phase or out of phase. Repeatedly, this eliminates the need for distance relays that use voltage and current inputs to mistake synchronization as an accident.
It is a response. Therefore, if the distance relay is configured to send a trip command to the circuit breaker,
It may be cut off accidentally when synchronization is lost. However, when out of synchronization, the power and current change gradually, and in the event of an accident, they change suddenly, so this is used to detect out of synchronization, and the output is used to lock the tripping circuit using the distance relay. As a countermeasure against unnecessary response when a protective relay device loses synchronization using a distance relay, it is often used in combination with the Maw element of a distance relay, which is generally used to trip a circuit breaker. An out-of-synchronization detection circuit is constructed in combination with an offset motor element having an even wider operating range than the above.

FIG. 1 is a block diagram showing the configuration of this type of conventional out-of-synchronization detection circuit. In the figure, 1 is a Moo element, 2 is an offset Moo element, 3°6 is a knot circuit, and 4 is a knot circuit.
5 is an AND circuit, 5 is an out-of-synchronization detection timer, and 7 is a flip-flop circuit.

In other words, the flip-flop circuit 7 uses the non-operation of the moor element 1 and the operation of the offset element 2 that continue for longer than the setting time limit of the out-of-synchronization detection timer 5 as a set side input, and uses the non-operation of the offset mole element 2 as a reset side input. The flip-flop circuit 7 is configured to send an output as an out-of-synchronization detection output only when a signal is input to the cell side. This output continues until a signal is input to the reset side.

FIG. 2 shows the operating characteristics (ranges) of the Maw element 1 and the offset Maw element 2, which are the constituent elements of FIG. 1, in an RX diagram. In Figure 2, A is the load impedance point of the power transmission line under normal conditions, B is the impedance of the power transmission line,
C shows the fault point impedance within the protection range, D shows the impedance locus at the time of loss of synchronization, and E shows the system fault point near the relay installation point.

Hereinafter, a conventional desynchronization detection circuit will be explained in detail with reference to FIGS. 1 and 2. The out-of-synchronization detection circuit shown in FIG. 1 detects out-of-synchronization by utilizing the fact that the transition time of the impedance locus is different at the time of a system failure and at the time of out-of-synchronization. In other words, in Fig. 2, first, when a system fault occurs, the impedance instantly shifts from load impedance point A to fault point C, so Moh element 1 and off-cellar 1 to Moo element 2 in Fig. 1 operate simultaneously, and Moh element 1 Since the output of is input to the AND circuit 4 via the NOT circuit 3, the AND condition is not satisfied. Therefore, the flip-flop circuit 7
is not set, and in this case, out-of-synchronization is not detected.

Next, when out-of-synchronization occurs, the impedance locus at the time of out-of-synchronization shown in FIG. 2 moves slowly on the RX diagram. Then, when this trajectory enters the operating range of Mo element 1,
Since the operation of the distance relay issues a tripping command to the breaker, causing an erroneous breaker, it is necessary to lock the tripping circuit by the distance relay using the output of the out-of-synchronization detection circuit shown in FIG. That is, when synchronization is lost, the offset Mo element 2 operates first, and at this time, the Mo element 1 does not operate, so the AND condition of the AND circuit 4 is established via the NOT circuit 3.
The out-of-synchronization detection timer 5 starts counting. When this out-of-synchronization occurs, the motor element 1 does not operate within the settling time limit of the out-of-synchronization detection timer 5, so a signal is input to the set side of the 5-flip-flop circuit 7, and at this time, the offset motor element 2 does not operate. Therefore, it is inverted by the NOT circuit 6 and no signal is input to the reset side. Therefore, the flop flip circuit 7 is set and its output is output to detect out-of-synchronization.

Now, there is no problem with the desynchronization detection circuit having such a configuration if the tripping command is instantaneously sent to the circuit breaker.
There is a slight problem when sending a trip command to a circuit breaker for a limited time. That is, as is well known, the system voltage is input to the polar coil of the Mor element via the voltage transformer.

For this reason, in the case of a system fault E near the relay installation point in FIG. 2, the system voltage drops significantly, and in the worst case, no voltage may be applied to the polar coil of the motor element. Therefore,
In general, a memory circuit is installed in the motor element to leave the pre-failure voltage in the polarity coil for several cycles to ensure reliable operation even in the event of a system fault near the relay installation point. In addition, since the offset motor element incorporates not only voltage but also current in its polar coil, it can operate satisfactorily even in the event of an accident near the relay installation point. Therefore, if the breaker tripping command is sent instantaneously, even if there is a system fault near the relay installation point, the motor element will not return midway, but the breaker tripping command will be sent for a limited time. In this case, the Mo element will return after several cycles of memory effect time.

Therefore, in the conventional out-of-synchronization detection circuit, the setting time of the out-of-sync detection timer 5 is the time limit for removing the breaker (naturally, in this case, the motor element for the breaker command is held in an external circuit).
In this case, due to the operation of the offset motor element 2 and the return of the motor element 1 due to the continuation of the accident, the out-of-synchronization detection timer 5 is timed up and a signal is input to the Ceramyl side of the flip-flop circuit 7. There is a problem in that reliability is low because the output is sent out to detect out-of-synchronization, and the breaker tripping circuit using the distance relay is locked, making it impossible to perform a time-limited breaker.

[Purpose of the invention]

The present invention was made in consideration of the above circumstances, and
The purpose is to provide a highly reliable protective relay device that can reliably detect and remove grid faults near the relay installation point in the case of time-limited interruption without mistaking the fault as an out-of-synchronization event. be.

[Summary of the invention]

In order to achieve the above object, the present invention continues to lock the out-of-sync detection circuit through the operation of the motor element, so that even in the event of a time-limited breaker, the out-of-sync detection output will cause the breaker to trip. This system is characterized by being able to reliably eliminate system faults without locking the circuit.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram showing a configuration example of an out-of-sync detection device applied to the protective relay device of the present invention.
Components that are the same as those in FIG. 1 are designated by the same reference numerals and their explanations will be omitted. In other words, in FIG. 3, the out-of-synchronization detection circuit in FIG.
and a flip-flop circuit 9 which uses the output of the Moo element 1 as a set side input, and uses the output of the offset Moo element 2 obtained via the knot circuit 8 as a reset side input, respectively.
In addition, the output of the flip-flop circuit 9 is sent out only when a signal is input to the set side, and this output is continuously sent out until a signal is input to the reset side.

In the out-of-synchronization detection device having such a configuration, when a system fault occurs, the impedance instantly shifts from the load impedance point A in FIG. 2 to the fault point C. At the same time, a signal is inputted to the set side of the flip-flop circuit 9 due to the operation of the MOE element 1, and no signal is inputted to the reset side via the NOT circuit 8 due to the operation of the offset MOE element 2. Therefore, although the flip-flop circuit 9 sends out an output, it is routed through the NOT circuit 3, so the AND condition of the AND circuit 4 is not satisfied and no out-of-synchronization is detected. Next, when the fault is removed, the offseller 1 hemo element 2 returns and a signal is input to the reset side of the flip-flop circuit 9 via the knot circuit 8.
The output of flip-flop circuit 9 is sent to reset 1.

On the other hand, even if the above-mentioned fault is a single system fault near the relay installation point, the impedance shifts instantly from the load impedance point A to the fault point E, so the moor element 1 and the offset moor element 2 operate simultaneously, and as described above, Similarly, the flip-flop circuit 9 is set. Then, Mo element 1
Even if the memory effect disappears and the motor element 1 returns, the output of the flip-flop circuit 9 continues to operate until the offset motor element 2 returns due to the removal of the fault. For this reason,
As explained in FIG. 1, when the motor element 1 is restored due to a system failure near the relay installation point, an out-of-synchronization detection output is not sent out and the circuit breaker tripping circuit is not locked.

Next, when the synchronization is lost, the offset motor element 2 operates first, and since the motor element 1 is not operating at this time, the flip-flop circuit 9 is not set and its output is not sent out.

Since this condition is inverted via the NOT circuit 310-, the AND condition of the AND circuit 4 is satisfied and the out-of-sync detection timer 5 starts counting. At the time of this out-of-synchronization, the motor element 1 does not operate within the settling time limit Js of the out-of-synchronization detection timer 5, so a signal is input to the set side of the flip-flop circuit 70, and at this time, the offset motor element 2 is operating. Therefore, the signal is inverted by the NOT circuit 6 and no signal is input to the reset side. Therefore, the output of the flip-flop circuit 7 is sent out to detect out-of-synchronization, and this out-of-synchronization detection output is sent out continuously until the offset motor element 2 returns.

In the above embodiment, an inverted version of the output of the offset motor element 2 was used as the reset side input of the flip-flop circuit 9, but this can be used as an accident detection element, such as an undervoltage detection element or an overcurrent detection element, to detect the output of the flip-flop circuit 9. It is also possible to use an inverted version of . In addition, the present invention is not limited to the above embodiments, and can be implemented with various modifications without changing the gist thereof.

〔Effect of the invention〕

As explained above, according to the present invention, the out-of-synchronization detection circuit is kept locked by the operation of the motor element, so even a system fault near the relay installation point in the case of a time-limited cutoff will not be mistaken as an out-of-synchronization. It is possible to provide an extremely reliable protective relay device that can reliably detect and eliminate an accident without causing a synchronization, and can also reliably lock the circuit by using an out-of-synchronization detection circuit to remove a circuit breaker when the out-of-synchronization occurs.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a conventional out-of-synchronization detection circuit, FIG. 2 is a characteristic diagram showing the operating ranges of the Moh element and the offset Moo element, respectively, and FIG. 3 is a schematic configuration diagram showing an embodiment of the present invention. It is. 1... Moo element, 2... Offset Moo element, 3゜6.8... Knot circuit, 4... AND circuit, 5...
・Out-of-synchronization detection timer, A, 9...Flip-flop circuit, A...Load impedance, B...Transmission line impedance, C, E...Fault point impedance, D
... Impedance trajectory when out of synchronization.

Claims (1)

[Claims] A distance relay is provided with a motor element as a distance element and an offset motor element having a wider operating range than the motor element, and which detects an accident by introducing the voltage and current of the power system and outputs a breaker trip command; an out-of-synchronization detection circuit that detects out-of-synchronization on the condition that the element is inoperative and the offset motor element is in operation for a predetermined period of time or more, and locks the breaker trip command with the output of the out-of-synchronization detection circuit; A protective relay device comprising means for locking the out-of-synchronization detection circuit under the condition that an element operates.