JPH02280618A - Protective relay device with countermeasure function to immobility of circuit breaker - 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 Industrial Application] The present invention relates to a protective relay device with a breaker deactivation device for stabilizing a power system.

[Conventional technology]

For example, Figure 5 (published by the Institute of Electrical Engineers of Japan on July 20, 1981)
Protection w1 electrical engineering pages 218-219, 224-226
1.2 is a circuit diagram of a conventional protective relay device with breaker deactivation device shown on page 1. In the figure, 1.2 is a power supply, lTR12
TR is transformer, CTI, C70 is current transformer, CBI-CB
S is a breaker, 01.02 is a bus bar, IL, 2L is a transmission line, 87 is a ratio differential relay for ITR transformer protection,
The operating coil OC is provided in a differential circuit that connects the secondary circuits of the current transformers CTI and C70 to each other, and the secondary circuit of the current transformer is energized by the inflow or outflow current from the differential circuit. Built-in suppression coils CRI and CR2 are provided in the circuit. 51F1 is an overcurrent relay provided in the secondary circuit of the current transformer R5CT1.

In this configuration, under normal conditions, from power supply 1 to transformer ITR
Load current 1o is flowing to. In this case, the current transformer CTI
, C70's secondary currents r, , r2 are equal in magnitude, so
The current flowing through the operating coil ○C, which is a differential circuit of the ratio differential relay 87, is 11Iz-O. Therefore, the ratio differential relay 87 is inoperative.

This ratio differential relay 87 includes current transformer CTI and current transformer CT2.
This is a four-relay relay whose suppressing force is the sum of the secondary currents. As for the suppressing force, the larger of the secondary currents of the current transformers CTI and Cr2, or the sum of the secondary currents may be used.

The reason why the suppressing force is added is to prevent the ratio differential relay 87 from malfunctioning due to a differential error current between the current transformers CTI Cr2 generated by a large through current in the event of an external failure.

When an internal fault occurs in the transformer ITR, a fault current 18, Ift, flows toward the transformer fault point F1. At this time, a current I flowing through the operating coil OC of the ratio differential relay 87
FI+IF! Since =≠0, the ratio differential relay 87 will operate.

FIG. 6 is a block diagram of a conventional breaker inoperation command output circuit, in which 3 is a ratio differential relay 87 and an overcurrent relay 5.
1F1 is an AND circuit which receives each output as input, and 4 is a timer circuit which operates upon receiving the output of AND circuit 3 and outputs a interrupter non-operation detection signal (hereinafter abbreviated as CBF signal) after a certain period of time.

As mentioned above, when an internal failure occurs in the transformer ITR, the ratio differential relay 87 operates and outputs a trip signal, trips the breaker CBI, stops the electric power, and connects the failure point to the power grid. separate from At this time, CBI
If the transformer ITR does not trip (open), a fault current of 1° continues to flow to the transformer ITR, which is detected by the overcurrent relay 51F1. As a result, the ratio differential relay 87
The timer circuit 4 is driven under the AND condition of simultaneous operation of the overcurrent relay 51F1 and the overcurrent relay 51F1.
5), a breaker non-operation detection signal (CBF signal) is sent.

When the CBF signal is output, circuit breakers CB3 and C84 are tripped. In other words, the breaker inoperation detection function detects that the breaker CBI has failed to trip (inoperation), and detects the breaker connected to the same bus as the inoperable breaker (in the case of Fig. 5, CBI, C84). , C84 are connected to the same busbar).

[Problem to be solved by the invention]

This conventional configuration has the following disadvantages, which will be explained with reference to FIGS. 7 and 8.

Figure 7 shows that when a normal load current of 1o is flowing,
This figure shows a case where a ground fault occurs at point F2 on the secondary side of current transformer CTI. In this case, since the secondary current I of the current transformer CTI flows from point F2 to point 82 -E of the ground, only the secondary current I2 of the current transformer CT2 flows into the operating coil OC of the ratio differential relay 87. flows, and ratio differential relay 87 operates, tripping circuit breaker CBI.

Figure 8 shows the state after the circuit breaker CBI has tripped, and the ground fault point of the secondary side F2 of the current transformer CTI is shown as E.
Let El be the grounding point on the z-ratio differential relay side.

Depending on the size of the power plant or substation, how equipment is placed, and how it is grounded, there may be a potential difference between points 81 and 82. If there is a potential difference between point 81 and point E, the ring current IX
will flow. Depending on the magnitude of this ring current rx, both the ratio differential relay 87 and the overcurrent relay 51F1 operate, so after driving the timer circuit 4 in FIG.
A signal will be issued.

In other words, when a ground fault occurs on the secondary side of the current transformer, even though breaker CB1 has tripped, it is determined that breaker CB1 is inoperable, and other breaker CB3 connected to the same mother vAO1 , there was a problem in that it tripped up to C84.

This invention was made in order to solve the above-mentioned problems, and aims to provide a protective relay device with a function to prevent breaker failure, in which no CBF signal is output in the event of a ground fault on the secondary side of a current transformer. purpose.

[Means to solve the problem]

The protective relay device according to the present invention includes a first current transformer and a second current transformer that are provided on the input side and the output side of the device to be protected and are differentially connected via a ratio differential relay. , a third current transformer is provided, and an overcurrent relay is interposed in the secondary circuit of the third current transformer, so that the output of the ratio operation protective relay, the output of the overcurrent relay, and the second A breaker non-operation command output circuit is provided which sends a breaker non-operation command when all three overcurrent relays interposed in the secondary circuit of the current transformer operate.

[Effect]

In this invention, only the overcurrent relay in the secondary circuit of the second current transformer of the first and second current transformers differentially connected via the ratio differential relay and the ratio operating relay operate. So,
Since the breaker non-operation command is not sent and the breaker non-operation command is sent only after the overcurrent relay of the third current transformer secondary circuit is also activated, the breaker non-operation command signal may be sent by mistake. There is no such thing as tripping all circuit breakers connected to the same bus.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In Figure 1, 5F1.5F2 are current transformers CT1, CT
This is an overcurrent relay installed in each of the secondary circuits of No. 3.

Since the other configurations are the same as those in FIG. 5, the same reference numerals are given.

FIG. 2 is a block diagram of the breaker non-operation command output circuit, and the AND circuit 3 is a ratio differential relay 87, an overcurrent '4g
! The outputs of the electric appliances 51F1 and 51F2 are input.

In this configuration, a load current 1o normally flows from the power source 1 to the transformer ITR. In this case, the current transformer CTI,
Secondary current of CT2 1. Since I2 has the same size, the operating coil o which is the differential circuit of the ratio differential 41 electric appliance 87
The current flowing through c is summer.

! 2=0. Therefore, the ratio differential relay 87 is inoperative.

If an internal fault occurs in the transformer ITR, the fault current 1. ,I, flows. At this time,
The current flowing through the operating coil OC of the ratio differential relay 87 is f
Since r++I□-≠0, the ratio differential relay 87 operates and issues a trip signal as shown in Figure 2, tripping the circuit breaker CBI, stopping the power supply 1, and removing the fault from the power system. Separate.

At this time, if there is a problem with the circuit breaker CBI,
If I does not trip, the fault current IF+ to the transformer ITR continues to flow, so that CT, c”ri of 2
Current also flows to the next side, overcurrent relay 51F1.51F2
work together. That is, since the ratio differential relay 87 and overcurrent relays 51Fl and 51F2 all operate, the AN
The output of the D circuit 3 becomes rHJ, drives the timer circuit 4, and sends out the CBF signal after a certain period of time (for example, after 100 ms). When the CBF signal is output, the same bus as CBI 01
The circuit breakers CB3 and C84 connected to the circuit trip.

Next, we will explain the operation when the F2 point on the secondary side of the current transformer CTI has a ground fault while the normal load current To is flowing.
The figure and FIG. 4 will be explained.

In this case, the secondary current I of the current transformer CTI flows from point F2 to point 82 - F3 of the ground, so the ratio differential relay 87
The secondary current of current transformer CT2 is applied to the operating coil OC! t flows, the ratio differential relay 87 operates, and the breaker CBI
Trisof.

FIG. 4 shows the state after the breaker CBI is tripped, and when there is a potential difference between the ground fault point of the current transformer CTl0 and the point 82, a ring current IK flows through the operating coil OC. Depending on the magnitude of this ring current lK, both the ratio differential relay 87 and the overcurrent relay 51F operate, but the overcurrent relay 51F
Since no current flows through the circuit No. 2, the overcurrent relay 51
F2 does not work. Therefore, the AND circuit 3 shown in FIG.
The AND condition is not satisfied, and the CBF signal is not sent.

Therefore, according to this embodiment, when a ground fault occurs on the secondary side of the current transformer, even though the breaker CBI has tripped, the breaker C
It is reliably prevented that the BI is determined to be inoperable and the other circuit breakers CB3 and C84 connected to the same bus ol are tripped.

〔Effect of the invention〕

As explained above, this invention includes two overcurrent relays for detecting breaker malfunction, one in the secondary circuit of a differentially connected current transformer, and the other in the secondary circuit of a current transformer that is connected differentially to another current transformer connected to the same power line. vessel 2
By providing a timer circuit in each of the following circuits and driving a timer circuit that sends a CBF signal when both of them and the ratio differential relay are operating, it is possible to connect the ground at one location on the secondary side of the current transformer. It is possible to prevent a CBF signal from being erroneously sent due to interference, and it is possible to improve reliability* compared to the conventional method.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing a breaker inoperation command output circuit in the above embodiment, and Figs. 3 and 4 explain the operation of the above embodiment. Figure 5 is a circuit diagram of a conventional circuit breaker malfunctioning protection device with electrical equipment cover device; Figure 6 is a block diagram showing a circuit breaker malfunction command output circuit in the conventional example; Figures 7 and 8 are explanatory diagrams of the operation of the device shown in Figure 5. In the figures, ITR - the transformer to be protected,
, CT2, CTa -- current transformer, OC-operating coil, 8
7-Protective relay (ratio differential relay) 51F1.51F2
・-・Overcurrent relay, 3-・-AND circuit, 4-timer circuit. In addition, in the figures, the same reference numerals indicate the same or relevant bones.

Claims (1)

[Claims] A first current transformer and a second current transformer are provided on the input side and the output side of the equipment to be protected, and a suppression coil and a differential current are connected to one end of the secondary side of both current transformers. In a protection relay device having a ratio differential relay having an operating coil, and an overcurrent relay inserted in the secondary circuit of the second current transformer,
a third current transformer that detects the same current as the second current transformer;
The third current transformer has an overcurrent relay inserted in the secondary circuit, and when the output of the ratio protection relay and the output of both overcurrent relays are input together, a breaker non-operation command is issued. A protective relay device with a breaker malfunction countermeasure function, characterized by having a circuit breaker malfunction command output circuit for sending out a breaker malfunction command.