JPS60144111A - Distance 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] [Field of Application of the Invention] 2. The present invention relates to a distance relay device, and particularly to a distance relay device suitable for protecting short-distance power transmission lines and determining failures at the nearest end of the relay device installation. .

[Background of the invention]

In the conventional distance relay method, when a near-end fault occurs, the voltage signal that serves as the reference for distance judgment approaches zero, making direction judgment impossible. Therefore, the direction of the failure point can be determined for a short time of about 2 to 3 cycles.

However, for distance relays such as back-up protection relays that require their original protective function several cycles or more after a failure occurs, the voltage signal of the memory circuit for about 2 to 3 cycles is Since memory alone cannot be used,
Once the device is in operation, various methods of maintaining the operation as shown in FIG. 1 are used.

FIG. 1(a) shows that after the Moh type relay 44M operates,
4 so that its own operating range includes the zero impedance point.
This method allows the distance relay to continue operating even if the voltage signal becomes zero in the event of a near-end failure by providing a characteristic that changes to 4M'. In the figure, R indicates resistance and jX indicates reactance.

In addition, the same figure (b) uses a combination of a Moo type relay 44M and a reactance relay 44X, and 44M and 44X are used in combination.
Since both 4X have operated, the presence or absence of a failure can be determined from now on only by the operation of 44X, and the entire operating range of the origin of impedance can be achieved.

In addition, Fig. 3(C) basically has the same idea as Fig. 6(b), and combines a rectangular distance relay 44Z and a direction relay 67B. This method continues the operating conditions at the time of a near-end failure.

In addition to this, there are also systems that use operating conditions such as an overcurrent relay or an undervoltage relay as conditions for maintaining the continued operation of the 44M.

As shown in the above example, the conventional system can continue operating the distance relay even in the event of a near-end failure. However, if a fault occurs at the external near end after an internal near end fault has occurred, there is a drawback that, despite the internal fault main protection operation, if the external fault continues, it will be incorrectly determined to be in the internal direction and shut off. .

When an internal near-end fault occurs, both the main protection relay for internal fault detection and the back-up protection distance relay shown in FIG. 1 become operational. In this case, the output of the main protection relay is used to open the breaker and immediately opens it, while the output of the backup protection distance relay is input to a timer and is used to open the breaker upon time-up.

However, in general, 44M in Figure 1 is used to open the breaker and eliminate internal faults by operating the main protection relay.

Since 44X and 44Z are inoperative, the distance relay is inoperative, so the timer will not time up. However, an internal failure is followed by a near-end external failure,
This is 44M', 44X.

44Z, the backup protection distance relay continues to operate despite the removal of the internal fault, and will eventually time out and give a trip signal to the circuit breaker. By the way, in general, the breaker is reclosed in the following order: occurrence of a fault in the system → fault removal → re-closing, but in the case of the above-mentioned continuous failures, the breaker may be accidentally shut off by the backup protection relay output after the re-closing is successful. (possibility of re-shutoff).

In addition to the above, one method is to increase the time constant of the memory circuit for the reference voltage for determining distance and direction to extend the time for determining operation, but the frequency continues to fluctuate during system failures. This poses a problem in implementation since it is possible that the direction will be incorrectly determined.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to prevent malfunction of a backup relay even when a failure occurs in a protection zone or a failure occurs behind the protection zone. □ [Summary of the Invention] The present invention is to prevent delayed determination at a fault point at the rear of the protection zone by adding a current phase carbonization detector for detecting current reversal to a distance relay.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

FIG. 2 is a diagram showing the overall concept of the present invention. The symbols and operations in the figure will be explained.

1 is the power transmission line to be protected, circle Y is the distance relay device according to the present invention, and when a failure occurs in the power transmission line 1, a cutoff command is issued when the failure point is in the forward direction, that is, in the direction of point F1 in the figure. is output to circuit breaker CB. CT is a current transformer for inputting the passing current signal of the power transmission line 1 to the distance relay device RY;
PT is a voltage transformer for inputting an applied voltage signal of the power transmission line 1 to the distance relay device RY. The distance relay device RY in this figure is a so-called back-up protection relay device, and performs tripping control of the circuit breaker when the main protection relay device (not shown) cannot operate.

Now, taking a Moh type distance relay as an example of the operating range of the - separation relay device BY, the settling reach is set to Z as shown in Fig. 2(b).
11! ! : When doing so, let zl be the impedance from the relay installation point to point F1, and let I+ be the fault current. Also, assume that the rear fault point is F2, the impedance is z, and the i fault current is 1°. Distance relay device RY has fault impedance Z
Even in the case of a near-end failure where I and 20 are close to zero, it is necessary to reliably identify whether it is the front or the rear. For this reason, as described above, a voltage signal serving as a reference for direction determination is applied to the memory circuit to temporarily continue the operation of the distance relay devices R and Y. However, as mentioned above, this memory circuit has limitations due to the problem of frequency fluctuations and the maintenance of high precision of the hardware, and the limit of the current system is that the memory can operate within several cycles. However, distance relay devices are often used for backup protection, and their operation duration is only 1.
It will take almost seconds. However, looking at recent system failures,
It is feared that lightning damage will occur over a wide area, power transmission line short circuits and ground faults will occur multiple times, and complex conditions will continue, such as high-speed shutoffs due to main protection and continued rear failures. Third
As shown in the figure, the holding of the operating output of the distance relay device is released by detecting the phase change of the current signal.

The symbols and operation contents in FIG. 3 will be explained.

(2) is a system voltage signal installed in a relay device, which is the output signal of the 21a PT, and (2) is a current signal, which is the output signal of the CT in FIG. 4
4M is a memory-operated mode type relay that can determine the direction even in the case of a near-end failure, and this part has the same function as the conventional back-up protection relay shown in FIG. The contents of the memory-operated Moh type relay 44M are as follows: 31 is a memory circuit for storing the voltage signal V; for example, it is a bandpass filter whose center frequency is the fundamental wave, and its attenuation characteristic is used to input the input ■ for a certain period of time. It stores and outputs V,.

32 is a distance setting circuit and from voltage v1 current I, V+=V −
Vector composition Z m I is performed, and Zi is the distance setting value. The calculation unit 33 uses the output V of the memory circuit 31 as a reference voltage signal, and uses the output V of the distance setting circuit 32 as a reference voltage signal.
−Z n I , the calculation of equation (1) is performed.

IV; l ・IV ZaIICO8θ>Kt-(1
) However, in equation (1), K1 is the level determination setting value, and θ is the phase difference angle between ■ and V-ZRI. When the equation (1) is satisfied, the flip-flop 34 is set to output an output. The output of flip-flop 34 is used as a breaker trip signal. However, as mentioned above, since this output is used as the output of the backup protection relay device, it will eventually be shut off after an appropriate time of about 1 second due to time coordination with the main protection relay device. It is used as a maiden name.

On the other hand, the output of the AND circuit 37 is applied to the reset terminal R of the flip-flop 34, thereby blocking the output of the clip-flop 34.

The FD that provides one of the inputs to the AND circuit 37 is a failure detection relay, and for example, a relay for undervoltage detection, overvoltage detection, overcurrent detection, etc. is used. AND circuit 37
78I, which provides another input to the current phase change detection circuit. In 78I, 35 is a memory circuit for current signals, and like the memory circuit 31, it can be implemented using a bandpass filter. The output of the memory circuit 35 is a signal delayed from the current input current signal, and this is designated as I.

36 is a phase comparison circuit, for example, lIp l
- Generates an output when lIt 1co3θr > Kz - (2). However, θ1 is the phase difference angle between H and L, and K2 is a setting value for level determination.

37 is an AND gate, which resets the output of the flip-flop 34 when there is no output from either the failure detection relay FD or the current phase change detection circuit 78I.

That is, after the memory-operated Moo-type relay 44M detects a failure in the protection zone and sets the flip-flop 34, at least the failure detection relay FD becomes inoperable, but the current phase change detection circuit 78I detects the direction of the input current signal. When a reversal is detected and the slip-flop 340 becomes inoperable, the slip-flop 340 set condition is canceled to prevent an erroneous disconnection command from being given when the direction of flow of fault current is reversed from the forward fault to the backward fault'. I can do it.

Although the operating conditions of the current phase change detection circuit 78I in FIG. , the phase angle determination angle may be arbitrarily determined as a fan-shaped operating range.

Moreover, although a Moh type relay is shown as an example for 44M, it may be a distance relay such as a quadrilateral or polygonal type, or a directional relay.

〔Effect of the invention〕

The distance relay device according to the present invention can exhibit its effectiveness in systems where there are many chances of fault current reversal, such as remote backup protection of multi-terminal systems, and can prevent unnecessary interruptions during system operation. The effect of stabilizing power system operation can be seen through this.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional system, FIG. 2 is an overall conceptual diagram of the present invention, and FIG. 3 shows a specific embodiment of the present invention. 44M...Distance relay, 34...Flip-flop, FD...Failure detection relay, 78I...Current phase change detection height 1t21 (C) Fig. 2 (a-2 (b)

Claims (1)

[Claims] 1. In a distance relay device that determines the direction of a fault point by inputting voltage and current signals from a power system, a distance relay device is characterized in that the operation determination output is controlled by detecting a phase change of the input current signal. Relay device.