JPH06165365A - Distance relay device - Google Patents

Abstract

PURPOSE:To prevent needless break by outputting a time limit change command only to the relay in waiting thanks for a rear provision protective function, according to the state of the opening and closing of the link breaker of a bus, when detecting the distant fault of a system from the voltage and the current of a transmission line and performing time limit break for rear provision. CONSTITUTION:Among substations A, B, and C, which have double bus systems with transmission lines 40 and 42, the distance between the substations A and B is supposed to be long and the distance between the substations B and C short. For example, in case that a fault occurs at the point f of a transmission line 40 and that the relay of the substation C does not operate, the relay 33a in the substation B and the relays 33c and 33d in the substation A detect the distant fault from the change of voltage and a current, as the relay on the second stage provided in the rear, and waits for trip with the time limit geared to the distance. Here, if the bus link breaker in the substation C is closed, the relays 33c and 33d performs the specified time limit operation with the command from the relay 33a. If the bus link equipment in the substation C is open, the relay 33d commands time limit operation only to the relay 33c. Hereby, unnecessary break is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance relay device for detecting a short circuit or a ground fault occurring in a power transmission line of a power system and giving a breaker command to a circuit breaker to eliminate the fault from the system.

[0002]

2. Description of the Related Art A conventional protection system will be described with reference to FIG. 4 showing a typical parallel two-line transmission system. In FIG. 4, A
Busbars 31a and 31b at the substation are
The bus lines are divided by two, and two parallel two-line power transmission lines are connected to each of the two routes, indicating that they are connected to the B, C, D, and E substations. Of course, the connection state of the power transmission lines is arbitrary, and each power transmission line may be connected to any bus bar of the A substation, and FIG. 4 shows an example thereof. 33 is a protective relay (hereinafter, protection relay) installed in the substation A for the transmission line 34, which is a current transformer 35 for measuring the current of the transmission line, and a transformer for measuring the voltage of the transmission line. 36 signals are given. It should be noted that there is essentially no difference even if the transformer for the instrument is installed on the busbar. Further, the protection relay 33 detects an accident, and when it judges that it should operate, gives a break command (trip command) 38 to the circuit breaker 37 to isolate the accident section and eliminate the accident from the system. Normally, a transmission line protection relay is equipped with main protection and back-up protection, the former is mainly provided for instantaneous protection against accidents that occur in the section of the transmission line, and the latter is instantaneous due to non-operation of the main protection relay. It is provided as a backup in case the accident was not eliminated. The backup protection relay is considered as a backup not only for transmission line accidents up to the next substation, but also for distant accidents. Therefore, a distance relay is usually adopted as a backup protection relay. This distance relay is based on the principle of measuring the impedance from the system voltage and current at the installation terminal to the fault point where the following calculations are performed.

[0003] V _R: A substation R-phase system voltage. V _S : A substation S-phase system voltage. I _R : A substation transmission line R-phase current. I _S : A substation transmission line S-phase current. I _O : A substation transmission line (own line) zero-phase current. I _O ′: A substation transmission line (adjacent line) zero-phase current.

As can be seen from the equations (1) and (2), the distance relay does not use the current information of the other substation side, and detects an accident far from the information of only the self-end. This is because the distance relay is different from the main protection relay in terms of principle and device configuration, and is due to a difference in purpose.
Therefore, in the case of an accident beyond the partner substation, the distance relay causes an error in distance measurement calculation in principle. This is due to the influence of the current flowing in from the transmission lines other than the own line connected to the partner substation busbar. In FIG. 4, C of the A substation to the transmission line protection relay for the A substation of the B substation,
This is the inflow current from the transmission lines for the D and E substations. The same thing occurs in the three-terminal transmission line as shown in FIG. This is due to the so-called shunt effect due to the inflow current from the rear of the C substation to the A substation relay 33.

Next, an example of the concept of settling of the distance relay for protection of the backup equipment will be described with reference to FIGS. 6 and 7. The distance relay is usually X ₁ , X ₂ , X ₃ , as shown in FIG.
(X ₄ ) has a protection characteristic of 3 (to 4) stages, and the protection sequence has time intervals T ₂ and T ₃ for elements from the second stage onward as shown in FIG. , (T ₄ )
Protects with. This is for time coordination with transmission line protection relays that are farther from the other party, and is designed so that a terminal close to the accident point issues a disconnection command in a shorter time and the minimum required disconnection is completed. . FIG. 8 shows an example of this time coordination. The horizontal axis represents distance (impedance) and the vertical axis represents time. The first stage is the distance settling of about 80% of the transmission line's own section, the instantaneous cutoff by the first stage operation, and the second stage T ₂
Timed shut off in the third stage is set to T ₃ TU blocked. This is the state in which the relay set value and the time settling are set in such a manner that they do not intersect between the substations, as shown in the figure, in a coordinated state. However, in reality, it is quite difficult to realize ideal cooperation as shown in FIG. This is because the transmission lines have various lengths and the performance limits of the distance relay. As described above, the distance measurement performance of the distance relay is affected by the current flowing from another transmission line of the partner substation, so the distance setting after the second stage can be operated reliably against the partner substation bus accident. This will be done in consideration of the possibility of backing up a distant accident. Therefore, when there is a short-distance transmission line and a long-distance transmission line in the next section, it becomes difficult to cooperate with the distance relay second stage in the next section. This causes difficulty in coordinating the remote protection relay including the second stage.

In FIG. 9, the transmission lines between the A and B substations and between the B and E substations are long, and the distance between the B and C substations is extremely short. The two-stage reach intersects with the distance relay second-stage reach installed in the B substation, causing an accident at a far point f as shown in Fig. 9, and the main protection relay (including the first stage of the backup equipment) is not available at the C substation. In the case of operation, the breaker trips at A substation, B substation, and E substation. In this case, the breaker trip at the A and E substations is essentially unnecessary. In addition, the main protection in case of an accident in the section,
Although the non-operation of the first stage of the backup equipment is considered to be small by definition, in many cases the first stage of the backup equipment is not used at all times or is locked in reality, and common parts such as current transformers are common. The cause is assumed to be due to a defect in. As a countermeasure against this, for example, there is a method according to Japanese Patent Publication No. 52-2096. This is the control to extend the second stage time limit of the backup equipment which protects the same direction of the neighboring substation from this terminal when the main equipment protection relay does not operate and the relay protection relay detects an accident. Figure
10 will be used to explain this aspect. If there is an accident at a distant point f, and the main protection relay at the C end is inoperative, the backup protection relay operates at the B substation, and the second stage protection time limit is applied to the A and E substations. A control signal 39 for extending T ₂ to T ₂ ′. This prevents the second-stage relays of the A and E substations from issuing a trip command to the circuit breakers all at once. This state is shown in FIG. The control command from the accident detection terminal to the controlled terminal described later is given through some communication line.

[0007]

The above-mentioned conventional method is an effective means, but when it is applied to a normally adopted double bus system, further improvement is required. As shown in FIG. 12, when an accident occurs at the point f of the transmission line 40 under the same condition as in FIG. 10 and the relay of the C substation is inoperative,
In B substation, the main protection relays 33a and 33b do not operate on both lines, and the relays 33c, 33d, 33e, and 33f of A substation and E substation are provided with the condition that the relay relays operate, and the time extension control of the second stage of the backup equipment is performed. Transmit signal. However, in the B substation, there are cases where the buses are separated and operated for system operation reasons. In such a case, relays 33d, 33 in FIG. 12 are used.
No control over f is required. Because in the double bus system C
A substation relay 33 installed in the substation detects an accident on the side of the transmission line 40 and trips the busbar breaker before the operation time of the second stage of the backup equipment.
This is because the substation relay 33f is restored. If there is an accident at another point and the relay 33b originally had to back up in the T ₂ time period, inconvenience would occur. Controlling time extension for a relay, which is originally a separate system, is out of purpose. The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a distance relay device in which a control command is given only to a terminal of the second stage of the backup equipment which requires time extension control.

[0008]

In order to achieve the above object, the present invention relates to a means for detecting a system fault by the voltage and current of a transmission line, a backup protection means for performing a time interruption for a distant fault, and A distance relay device equipped with a judgment means for changing and controlling the backup protection time limit for a relay having a remote protection function in the same direction installed in another substation facing the substation According to the open / close state of the circuit breaker, the time change control command of the relay having the protection function is provided.

[Operation] When the condition that the bus-barrier breaker at the signal transmitting end is closed is satisfied, the main protection relay non-operation condition and the time extension control condition composed of the AND operation of the backup relay are unconditionally opposed. It is transmitted as a control command to the relay of the same direction protection at the substation. Further, when the condition that the busbar circuit breaker is closed is not satisfied, the signal is transmitted only to the corresponding opposite relay.

[0009]

Embodiments will be described below with reference to the drawings. Figure 1
Is a distance relay device according to the present invention, FIG. 1 (a) shows a device configuration for transmitting busbar connection conditions to other substations, and FIG. 1 (b) is a configuration diagram for giving a trip command to the distance relay. is there. In Fig. 1 (a), 1 is the condition that the busbar breaker at the signal transmission end is closed, 2 is the condition that the main protection relay is not operating,
3 is a backup relay operating condition, 4 is a time protection control condition consisting of a main protection relay non-operating condition 2 and a backup relay operating condition 3, and 5 is another transmission connected to the same bus as the transmission line. It is a condition for detecting an electric wire. Therefore, when the condition that the busbar circuit breaker at the signal transmitting end is closed is satisfied, the main protection relay non-operation condition 2 and the auxiliary relay operation condition 3 and the time extension control condition 4 consisting of AND The control command is transmitted to the relay of the same direction protection at the opposite substation according to the condition. Further, when the condition 1 is not satisfied, only the corresponding opposite relay is controlled by ANDing with the condition 5 that detects another transmission line connected to the same bus as the transmission line detecting the condition 4. Send command.

Now, if the control command 6 is not received, FIG.
As shown in, there is no control command transmission reception condition 7,
Since the inhibit conditions of the second stage is established, the second stage time period is T _2, thus the distance relay Overall, the X ₁ Come to instantaneously tripped in each set time period of the X ₂ T _2, X ₃ in T _3. However, if the control command 6 is received, the above condition is not satisfied, and as a result, the second stage time period is extended to T ₂ ′. In this case, T ₂ <T ₂ ′ <T ₃ is appropriate for the time scale. No special control is provided for timed trips of the third stage or higher.

Next, the operation will be described with reference to FIG. Similar to FIG. 9 described above, FIG. 3 assumes that a short distance transmission line is provided between the B substation and the C substation, and an accident occurs at the point f of the transmission line 40.
If the substation relay is not working, B substation relay 33
a, A substation relays 33c and 33d are second-stage relays f
A point accident has been detected and the device is on standby for a timed trip. Where B
The other transmission line relay of the substation is omitted because it is restored by the operation of the bus separation relay 41 in the B substation. The extension control condition 4 of the second stage time period is satisfied in each of the relays. If the C substation bus breaker is closed, both relays 33c and 33d are relays.
Receives from the instruction 6 33a, second stage operates after time period of T ₂ '. This is coordinated with the second stage time limit T ₂ of the B substation 33a relay. When the busbar breaker is open, the B substation relay 33a gives a control command only to the A substation relay 33c. That is, the relay 33d remains in the normal second stage trip time limit. At this time, for example, if an accident occurs on the power transmission line 42, the second stage of the backup equipment of the relay 33d can be dealt with by the normal time period T ₂ .

[0012]

As described above, according to the present invention, the distance relay having the backup protection function in the same direction of the substation facing the substation is provided with the second relay according to the self-bus communication condition.
Since it is configured to enable or disable the extension control of the post-stage backup time period, it is possible to perform time period protection suitable for the system state.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a distance relay device according to the present invention.

FIG. 2 is a diagram showing the busbar connection status.

FIG. 3 is a diagram illustrating an operation.

FIG. 4 is a diagram showing a conventional protective relay system.

FIG. 5 is a diagram showing a case of a three-terminal power transmission line.

FIG. 6 is a diagram showing protection characteristics of a distance relay.

FIG. 7 is a diagram showing protection characteristics of a distance relay.

FIG. 8 is a diagram showing time coordination of a distance relay.

FIG. 9 is a diagram showing protection time coordination of each substation.

FIG. 10 is a diagram showing inconvenience of the conventional device.

FIG. 11 is a diagram showing the inconvenience of the conventional device in time coordination.

FIG. 12 is a diagram showing a disadvantage of the conventional device in a system diagram.

[Explanation of symbols]

 1 Busbar contact “closed” condition 2 Main protection relay “non-operation” condition 3 Backup protection relay “operation” condition 5 Same busbar “connection” condition 6 Control command transmission command 7 Control command transmission reception condition

Claims (1)

[Claims] 1. A means for detecting a system fault by means of the voltage and current of a transmission line, a backup protection means for timely shutting off a distant fault, and the same unit installed at another electric station opposite to the electric station. A distance relay device, comprising: a relay device having a distant directional protection function, and a determination means for changing and controlling a backup protection time period in accordance with the open / closed state of a bus bar communication breaker of a bus.