JP2000175346A - Overcurrent relay coordination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable improving operating precision of an overcurrent relay coordination device. SOLUTION: This overcurrent relay coordination device is provided with a memory circuit 6 previously storing the value of a flowing current where protective coordination of an upperstream side relay 2 and a downstream side relay 3 is not established, comparing circuits 7, 8 comparing a current value 1a which is previously stored in the memory circuit 6 with an upperstream side flowing current I1 or a downstream side flowing current I2, a delay circuit 9 delaying an output of the comparing circuit 7 by a specified time when the current value 1a is smaller than the upperstream side flowing current I1, and a synthesizing circuit 10 operating logic product of the output of the delay circuit 9 and the output of the upperstream side relay 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overcurrent relay coordination device which is added to realize overcurrent coordination characteristics when there are two or more protection relays which cannot take overcurrent protection coordination.

[0002]

2. Description of the Related Art When a switchboard is added downstream of a conventional switchboard, it is necessary to coordinate protection by two or more protective relays. However, when the characteristics unique to the protective relay do not match, coordination cannot be achieved, or the protective relay must be replaced or the current transformer must be replaced, resulting in a significant modification of the switchboard, and work cannot be performed due to energization. Sometimes. For this reason, protection coordination cannot be achieved in many cases.

[0003]

In the work of coordinating protection relays, which has been considered difficult in the prior art, the overcurrent relay coordinator of the present invention is added to the outside to protect the protection relay mounted on the switchboard. It is possible to ensure protection coordination of relays. As a result, it is an object of the present invention to provide an overcurrent relay coordinating device that does not require a significant system change or modification of the protection relay.

[0004]

The overcurrent relay coordinating device of the present invention is characterized in that the protection protection coordination of two or more protection relays is classified into patterns and set in the proposed circuit in advance. And

An overcurrent relay coordinating device according to a first aspect of the present invention includes an upstream relay installed on a power supply side of a system and operating by detecting an upstream conduction current flowing through a power supply system circuit, and an overcurrent relay of the upstream relay. A circuit breaker trip output circuit to which a protection operation contact signal is supplied, an upstream circuit breaker to which a trip output of the circuit is supplied, and which disconnects the power supply system circuit;
A downstream relay which is installed on the load side of the system and detects and operates a downstream conduction current flowing through the load system circuit, and a breaker trip output circuit to which an overcurrent protection operation contact signal of the downstream relay is supplied, A trip output of this circuit is supplied, and a downstream circuit breaker that disconnects the load system circuit, and a memory that previously stores a predetermined energizing current value indicating a range in which protection coordination between the upstream relay and the downstream relay cannot be performed. A circuit for comparing the current value stored in the memory circuit with the upstream current and the downstream current, and an overcurrent protection operation of the upstream relay based on a comparison result by the comparison circuit. A delay circuit for delaying the contact signal or the contact signal for overcurrent protection operation of the downstream relay by a predetermined time.

In other words, in the time limit characteristic region of the protection relay mounted on the upstream side and the protection relay mounted on the downstream side, the current one-hour characteristic of the higher-order protection relay should originally be positioned above the characteristic of the downstream protection relay. The kimono is located below the downstream protection relay characteristic when the time-current characteristic of the upper protection relay is equal to or more than the determined current value Ia.

In this case, the input current value of the upstream protection relay is I ₁ , and the input current value of the downstream protection relay is I ₂ , and the respective magnitudes are compared as follows to determine the operating state of the protection relay. Control.

(1) If I ₁ > Ia AND I ₂ > Ia: It is determined that the current is caused by an accident that has occurred downstream of the downstream relay. The proposed circuit delays the operation of the upstream relay by the specified time so that the upstream relay operates after the downstream relay, preventing the trip of the upstream circuit breaker,
A process for operating the downstream circuit breaker first is performed.

(2) If I ₁ > Ia AND I ₂ <Ia: It is determined that the current is caused by an accident that has occurred downstream of the upstream relay and upstream of the downstream protection relay. In the proposed circuit, the upstream circuit breaker is tripped according to the characteristics of the relay without processing the operation of the upstream relay.

According to a second aspect of the present invention, there is provided an overcurrent relay coordinating device, wherein a first input circuit for inputting a protection operation contact of the first overcurrent protection relay and a second input circuit located downstream of the first overcurrent protection relay. A second input circuit for inputting the protection operation contact of the second overcurrent protection relay and the first and second overcurrent protection relays in a range where the protection coordination of the first and second overcurrent protection relays cannot be achieved. A memory circuit for storing a time necessary for time coordination, a delay circuit for performing contact output after a predetermined time in the first and second input circuits by the memory circuit, and a delay circuit for the delay circuit. And an output circuit provided to trip a circuit breaker corresponding to the first or second overcurrent protection relay according to the output.

That is, in the reciprocal time characteristic region of the protection relay mounted on the upstream side and the protection relay mounted on the downstream side, a sufficient operation time difference between the characteristic curves is taken to allow an error in operation and a disc of the induction disk type. It is necessary to be able to break unnecessary motion due to inertial motion. However, if the operation time difference cannot be sufficiently obtained due to the characteristics of the mutual protection relays at a certain current value Ib or more, not only the downstream relay operation but also the upper relay will operate. Therefore, the proposed circuit controls the operation of the upstream circuit breaker to be delayed based on the current value of the upstream side relay and the input current value of the downstream side relay.

(1) If I ₁ > Ia AND I ₂ > Ib: It is determined that there is not a sufficient time difference between the operation times of the upstream relay and the downstream relay. The proposed circuit performs a predetermined delay process for the operation of the upstream relay and then trips the upstream circuit breaker. If a secondary fault occurs in the downstream relay and the downstream circuit breaker has tripped normally, the fault current is eliminated, the operation of the upstream relay stops, and the upstream circuit breaker does not trip.

According to a third aspect of the present invention, there is provided an overcurrent relay coordinating device, wherein a first input circuit for inputting the same current element as the short-circuit protection instantaneous element protection relay, and an input circuit located downstream of the instantaneous element protection relay. A second input circuit that inputs the same current element as the current of the instantaneous element protection relay, a circuit that captures the operating contact of the instantaneous element of the two instantaneous element protection relays, and a predetermined circuit that indicates a range where protection coordination cannot be achieved. A memory circuit for storing a current value; a comparison circuit for comparing the current value stored in the memory circuit with the values of the first and second input circuits; A delay circuit that outputs a contact, a synthesizing circuit that takes an AND state of an output of the delay circuit and an output of a circuit to which an operating contact of the instantaneous element protection relay is input, It is characterized by comprising an output circuit which is provided to trip.

That is, in the instantaneous operation region of the protection relay mounted on the upstream side and the protection relay mounted on the downstream side, it is general that mutual coordination cannot be achieved. This means that the instantaneous element of the upstream relay operates first due to the secondary fault current of the downstream relay and trips the upstream circuit breaker. Such, in the instantaneous operation region at a certain current value Ic above, the input current I2 of the current value I ₁ and the downstream relay upstream relay,
Control is performed to delay the trip operation of the upstream circuit breaker.

(1) In the case of I ₁ > Ia AND I ₂ > Ic: It is determined that the operation area is an operation area by the instantaneous element of the upstream relay and the downstream relay. According to the circuit of the present invention, the upstream circuit breaker is tripped after a predetermined delay processing for the operation of the upstream relay. If the secondary side fault of the downstream side relay has occurred and the downstream side breaker has tripped normally, the fault current is eliminated and the operation of the upstream side relay stops, and the upstream side breaker does not trip.

With the above-described configuration, the current-hour characteristic curve of the upper-layer relay is originally different from that of the lower-layer relay in the time limit characteristic region of the protection relay mounted on the upstream side and the protection relay mounted on the downstream side. According to the present invention, even if the one to be located on the upper side of the current-time characteristic curve is located below the downstream-side relay characteristic when the time-current characteristic of the upper-side relay is equal to or more than the determined current value, By comparing the input current value of the upstream relay and the input current value of the downstream relay, the operating state of each protection relay can be controlled.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the overcurrent relay coordinator according to the present invention will be described.

In FIG. 1, an upstream relay 2 is provided on the power supply side of the system and has an upstream current I
_The upstream circuit breaker 4 is a circuit switch that is connected in series with the upstream relay 2 and disconnects the power system circuit by the operation of the upstream relay 2.

Further, the downstream-side relay 3 is overcurrent relay which operates by detecting the downstream flowing current I ₂ flowing through the load system circuit is provided on the load side of the system, downstream breaker 5 downstream relay 3 And a circuit switch for disconnecting the load system circuit by the operation of the downstream relay 3.

The memory circuit 6 is a circuit that stores in advance the current value Ia which is a section in which protection coordination is not taken. The comparison circuit 7 is connected to the upstream relay 2, the downstream relay 3 and the memory circuit 6, a circuit for comparing the magnitude of the downstream flowing current I ₂ on the upstream side applied current I ₁ or downstream relay third current value Ia and the upstream relay 2 of the memory circuit 6.

Similarly to the comparison circuit 7, the comparison circuit 8 is connected to the upstream relay 2, the downstream relay 3 and the memory circuit 6, and the current value Ia of the memory circuit 6 and the upstream conduction current I ₁ of the upstream relay 2 Alternatively, it is a circuit for comparing the magnitude of the downstream side conduction current I ₂ of the downstream side relay 3.

The delay circuit 9 is connected to the comparison circuit 7 and delays the output of the comparison circuit 7 by a predetermined time when the current value Ia <I _1. The synthesis circuit 10 is an output circuit of the upstream relay 2. And the delay circuit 9
Is a circuit for calculating a logical product AND of the output of the upstream relay 2 and the output of

The combining circuit 11, unlike the combining circuit 10, is not connected to the delay circuit, but is connected to the output circuit of the downstream relay 3 and the comparison circuit 8, and performs the logical product of the output of the comparison circuit 8 and the output of the downstream relay 3. This is a circuit for calculating AND.

The circuit breaker trip output circuit 12 is
0 and trips the upstream circuit breaker 4 (trip)
The circuit breaker trip output circuit 13 is connected to the combining circuit 11 and generates a signal for tripping the downstream circuit breaker 5.

The comparators 7 and 8, the delay circuit 9, the synthesizing circuits 10 and 11, and the circuit breaker trip output circuits 12 and 13 form a main body of the overcurrent relay coordinator 1.

FIG. 2 shows the characteristic A of the upstream relay 2 and the characteristic B of the downstream relay 3, with the horizontal axis representing current and the vertical axis representing time. When a current smaller than the current value Ia flows, the protection relay of the upstream relay 2 and the downstream relay 3 is coordinated. However, coordination is not achieved when the current value Ia is exceeded. This will be described with reference to the magnitude of the flowing current.

(1) When I ₁ <Ia and I ₂ <Ia The upstream-side current I _{1 of the} upstream-side relay 2 and the downstream-side relay 3
Since the downstream-side current I ₂ is smaller than the current value Ia, the downstream-side relay 3 operates before the upstream-side relay 2, so that the effect of the delay circuit 9 need not be added.

(2) When I ₁ > Ia and I ₂ > Ia The upstream-side current I _{1 of the} upstream-side relay 2 and the downstream-side relay 3
Since the downstream flowing current I ₂ is greater than both current Ia, it is determined from the downstream breaker 5 and accident downstream,
It is desirable that the downstream circuit breaker 5 be tripped by the downstream relay 3. However, when the delay circuit 9 does not function, the upstream circuit breaker 4 trips because the operating characteristics of the upstream relay 2 are fast from the characteristics A and B in FIG. Therefore, by utilizing the overcurrent relay coordinating device 1, the trip time of the upstream circuit breaker 4 is delayed by a predetermined time by the operation of the delay circuit 9, so that the downstream relay 3 is operated first.

An overcurrent relay coordinating device according to a third aspect of the present invention includes a first input circuit 2a for inputting the same current element as the short-circuit protection instantaneous element protection relay, and an input circuit located downstream of the instantaneous element protection relay. A second input circuit 3a for inputting the same current element as the current of the instantaneous element protection relay, a circuit for receiving the operating contacts of the instantaneous elements of the two instantaneous element protection relays, and a predetermined circuit indicating a range where protection coordination cannot be achieved. A memory circuit 6 for storing a current value, comparison circuits 7 and 8 for comparing the current value stored in the memory circuit 6 with the values of the first and second input circuits, and comparison results of the comparison circuits 7 and 8 A delay circuit 9 that outputs a contact after setting a timer, a combination circuit 10, 11 that takes an AND state between an output of the delay circuit 9 and an output of a circuit to which an operating contact of the instantaneous element protection relay is input, Output It is characterized by comprising a circuit breaker trip output circuit 12 which is provided to trip the more breaker.

Therefore, in this case, it is common that mutual protection cannot be achieved in the instantaneous operation region of the protection relay mounted on the upstream side and the protection relay mounted on the downstream side. And, it means that the instantaneous element of the higher-order protection relay operates first and trips the higher-order circuit breaker due to the secondary fault current of the downstream protection relay. If the protection in the instantaneous element region cannot be achieved at a certain current value or more, control is performed so that the trip operation of the circuit breaker is delayed by the current value of the upper-side relay and the input current of the downstream-side relay.

(3) In the case of I ₁ > Ia and I ₂ <Ia The location of the accident is systematically between the upstream circuit breaker 4 and the downstream circuit breaker 5, and the normal operation is performed by the operation of the upstream relay 2. It is.

An overcurrent relay coordinating device according to a second aspect is provided with a first input circuit 2a for inputting a protection operation contact of the first overcurrent protection relay and a downstream of the first overcurrent protection relay 2a. The second input circuit 3a for inputting the protection operation contact of the second overcurrent protection relay, and the first and second overcurrent protection relays in a range where the protection coordination of the first and second overcurrent protection relays cannot be achieved. A memory circuit 6 for storing a time required for time coordination of the current protection relay;
And a delay circuit 9 that outputs a contact after a predetermined time in the memory circuit 6 to the second input circuit, and trips a circuit breaker corresponding to the first or second overcurrent protection relay by the output of the delay circuit 9 And a circuit breaker trip output circuit 12 provided for the purpose.

Therefore, in this case, in the instantaneous operation region of the protection relay mounted on the upstream side and the protection relay mounted on the downstream side, the operation time difference between the characteristic curves is originally sufficiently taken, and the allowable error and the induction in the operation are obtained. It is necessary to avoid unnecessary operation due to inertial operation in a disk type instrument. However, when mutual cooperation cannot be achieved at a certain current value or more, not only the downstream protection relay but also the upper protection relay operates. Therefore, the trip operation of the circuit breaker is controlled to be delayed by the current value of the upper relay and the input current of the lower relay.

(4) Case of I ₁ <Ia and I ₂ > Ia This case does not exist in principle in the embodiment.

FIG. 3 shows that the time limit characteristics of the upstream relay 2 and the downstream relay 3 are extremely close to each other in a range larger than the current value Ia, and in the case of a characteristic error of the relay or an induction disk type,
There is a concern about unnecessary operation of the overcurrent relay on the upper side due to its inertia. In this case, if the overcurrent relay coordination device 1 is employed, it is possible to delay the trip operation of the upstream circuit breaker 4 by the upstream relay 2 in the unnecessary operation range.

FIG. 4 shows that in the range larger than the current value Ia, coordination cannot be achieved because the upstream relay 2 and the downstream relay 3 each have instantaneous characteristics. Also in this case, if the overcurrent relay coordinating device 1 is adopted, the instantaneous element of the upstream relay 2 can be delayed by a predetermined time, so that even if a short circuit accident occurs downstream of the downstream circuit breaker 5, the upstream circuit breaker 4 is not required. Operation can be prevented.

[0037]

According to the present invention, when the two protective relays cannot adjust the setting mutually due to their characteristics, or when the additional setting of the switchboard does not allow the proper setting in the work process, the present invention is applied. Overcurrent protection coordination can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an overcurrent relay coordination device showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the operation of the overcurrent relay coordinating device of FIG.

FIG. 3 is an explanatory diagram showing an operation of the overcurrent relay coordinating device of FIG. 1;

FIG. 4 is an explanatory diagram showing an operation of the overcurrent relay coordinating device of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Overcurrent relay coordination device 2 Upstream relay 3 Downstream relay 4 Upstream circuit breaker 5 Downstream circuit breaker 6 Memory circuit 7 Comparison circuit 8 Comparison circuit 9 Delay circuit 10 Synthesis circuit 11 Synthesis circuit 12 Circuit breaker trip output circuit 13 Circuit breaker Trip output circuit

Claims (3)

[Claims] An upstream relay that is installed on a power supply side of a power system and detects and operates an upstream current flowing in a power supply system circuit, and a circuit breaker trip to which an overcurrent protection operation contact signal of the upstream relay is supplied. An output circuit, an upstream circuit breaker to which a trip output of the circuit is supplied and disconnects the power supply system circuit, and a downstream side which is installed on the load side of the system and detects and operates a downstream conduction current flowing through the load system circuit. A relay, a circuit breaker trip output circuit to which an overcurrent protection operation contact signal of the downstream side relay is supplied, a downstream circuit breaker to which a trip output of the circuit is supplied and disconnects the load system circuit, and the upstream side relay A memory circuit for storing in advance a predetermined energizing current value indicating a range in which protection coordination with the downstream relay cannot be performed, and the energizing current value stored in advance in the memory circuit, A comparison circuit for comparing the flow-side energizing current and the downstream-side energizing current, and, based on a result of the comparison by the comparison circuit, an overcurrent protection operation contact signal of the upstream relay or an overcurrent protection operation contact signal of the downstream relay, An overcurrent relay coordination device, comprising: a delay circuit that delays by a time. 2. A first input circuit for inputting a protection operation contact of a first overcurrent protection relay, and a protection operation contact of a second overcurrent protection relay located downstream of the first overcurrent protection relay. In a range where the protection coordination between the first and second overcurrent protection relays cannot be achieved with the second input circuit for inputting A memory circuit for storing time,
A delay circuit that outputs a contact to the first and second input circuits after a predetermined time in the memory circuit, and the output of the delay circuit corresponds to the first or second overcurrent protection relay. An overcurrent relay coordinator, comprising: an output circuit provided to trip the circuit breaker. 3. A first input circuit for inputting the same current element as the short-circuit protection instantaneous element protection relay, and a current identical to the current of another instantaneous element protection relay located downstream of the instantaneous element protection relay. A second input circuit for inputting an element, a circuit for capturing operating contacts of instantaneous elements of the two instantaneous element protection relays, a memory circuit for storing a predetermined current value indicating a range in which protection coordination cannot be achieved, A comparing circuit that compares the current value stored in the memory circuit with the values of the first and second input circuits, a delay circuit that outputs a contact after setting a timer based on a comparison result of the comparing circuit; And an output circuit provided for tripping the circuit breaker with the output of the composite circuit. An overcurrent relay coordinating device characterized in that: