JP2003153430A - Network protector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a network protector for preventing the break error of a protection circuit breaker due to an inrush load current. SOLUTION: A current phase angle detection relay 23 has characteristics for operating when the phase angle of current flowing into a load side is delayed by 0-π/2 to a network bus voltage Vn. A control circuit 24 opens a protector circuit breaker 15 when the current phase angle detection relay 23 does not operate and the operation state of the network relay 21 continues at least for a specific time. As a result, the control circuit 24 judges that the reverse power (current) detected by a network relay 21 is not the reverse power and prevents a circuit break signal from being outputted to the protector circuit breaker 15 even if the network relay 21 detects the inverse power (current) when the phase to the network bus voltage Vn in a load inrush current is in the fourth quadrant, thus preventing break error to the load inrush current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network protector for protecting a load side of a network distribution system in which electric power is distributed from a plurality of high voltage distribution lines to the load side.

[0002]

2. Description of the Related Art Generally, a network power distribution system supplies power from a plurality of high voltage distribution lines to a network bus, and further supplies power from the network bus to a load side through a protector circuit breaker. As a high power distribution system, it is mainly used in high-load overcrowded areas in urban areas. Usually, the high-voltage distribution line of two or more lines receives power to the network bus through the load transformer, and the secondary side of the load transformer is always operated in parallel via the network protector.

FIG. 6 is a system diagram of such a network power distribution system. Usually, electric power is received from two or more high-voltage distribution lines to the network bus bar 13 via the load transformer 11 and the take-off circuit breaker 12, and electric power is supplied to a plurality of load sides via the network protector 14. .

In the network protector 14, the electric power of the network bus 13 is supplied to the load side through the protector circuit breaker 15, the transaction instrument transformer / current transformer 16, the network transformer 17 and the load disconnector 18. In addition, the voltage supplied from the network bus 13 to the load side is detected by the voltage transformer 19 and input to the phase comparison relay 20, and the network relay 21 is connected to the voltage transformer 19.
Input the voltage through and the current through the network current transformer 22. Then, the protector circuit breaker 15 is cut off when reverse power flows into the load side or when there is an overvoltage.

That is, the network protector 14
Is the reverse power (current) cutoff, differential voltage input, no voltage input 3
It has two automatic control functions. Among these three automatic control functions, the reverse power (current) cutoff function is used to protect the network protector 1 from a healthy line when the distribution line is stopped or when an accident occurs.
Reverse power (current) flowing to the stop line via 4 is detected by the network relay 21 and the corresponding protector breaker 15
Shut off and continue to supply power through a healthy line.

FIG. 7 is an operational characteristic diagram of the network relay 21. As shown in FIG. 7, the network relay 2
The disconnection operation detection characteristic (maximum sensitivity angle Φ) of 1 has a slope of the lead angle with respect to the network bus voltage Vn in consideration of the reverse power (current) aspect of the network distribution system. That is, the protector breaker 1 of the network relay 21
5 detection characteristic curve S1 and interruption detection characteristic curve S2
Are characteristics orthogonal to the maximum sensitivity angle Φ and have characteristics of a closing area E1 and a cutoff area E2, respectively.

[0007]

However, when power is distributed to a load, there is a load inrush current It (excitation inrush current in the case of a transformer), and the reverse power (current) interruption operation detection characteristic of the network relay 21. Has a forward angle, the network relay 21 may operate (reverse power (current detection)) depending on the magnitude of the inrush current It. In this case, the protector breaker 15 interrupts reverse power (current) even though the power system is normal and the protector passing current is in the forward direction. Depending on the magnitude of the inrush current, all protector circuit breakers 15 may be cut off. Therefore, conventionally, the interruption command is delayed until the inrush current It decays.

However, since the inrush current It and the continuation time differ depending on the capacity and characteristics of the load side transformer or the closing phase, the maximum value must be assumed, and the delay time must be the reverse power (current) interruption protection coordination. It is fully possible not to establish. For this reason, measures other than those due to the delay of the cutoff command are required.

An object of the present invention is to provide a network protector capable of preventing erroneous disconnection of a protector circuit breaker due to load inrush current.

[0010]

A network protector according to the invention of claim 1 supplies power to a network bus from a plurality of high voltage distribution lines, and further supplies power from the network bus to a load side through a protector circuit breaker. In a network protector for protecting the load side of the network distribution system for supplying, a current phase angle detection relay that operates when the phase angle of the current flowing into the load side is a delay of 0 to π / 2 with respect to the network bus voltage. A network relay that prevents reverse power from flowing from the load side to the network bus, and the protector breaker when the current phase angle detection relay is inoperative and the operating state of the network relay continues for a predetermined time period or longer. And a control circuit for opening.

In the network protector according to the first aspect of the present invention, in the current phase angle detection relay, the phase angle of the current flowing into the load side is 0 to the network bus voltage.
The control circuit has a characteristic of operating when the delay is π / 2, and the control circuit opens the protector circuit breaker when the current phase angle detection relay is inactive and the operating state of the network relay continues for a predetermined time period or longer. As a result, when the phase of the load inrush current with respect to the network bus voltage is in the 4th quadrant, the control circuit determines that the reverse power (current) is not detected even if the network relay detects the reverse power (current) and shuts off to the protector circuit breaker. Since no signal is output, it is possible to prevent erroneous interruption of the load inrush current.

A network protector according to a second aspect of the present invention is of a network power distribution system in which power is supplied from a plurality of high voltage distribution lines to a network bus, and further, power is supplied from the network bus to a load side through a protector breaker. In a network protector that protects the load side, a network relay that prevents reverse power from flowing from the load side to the network bus, and a phase advancing capacitor that is turned on to the load side when the network relay operates and the network. And a control circuit for opening the protector breaker when the operating state of the relay continues for a predetermined time period or longer.

In the network protector according to the second aspect of the present invention, the control circuit turns on the phase advancing capacitor on the load side when the network relay operates, and
When the operating condition of the network relay continues for a specified time or longer, open the protector breaker. Since the load inrush current is advanced by turning on the phase-advancing capacitor, it is possible to prevent erroneous interruption by moving away from the interruption characteristic range of the network relay.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a system diagram of a network power distribution system to which a network protector 14 according to an embodiment of the present invention is applied. This embodiment is different from the conventional example shown in FIG. 6 in that the current phase angle detection relay 23 operates when the phase angle of the current flowing into the load is delayed by 0 to π / 2 with respect to the network bus voltage Vn. And a control circuit 24 for opening the protector breaker 15 when the current phase angle detecting relay is not operating and the operating state of the network relay 21 continues for a predetermined time period or longer. Since other configurations are the same as those of the conventional example shown in FIG. 5, the same elements are denoted by the same reference numerals, and duplicated description will be omitted.

In FIG. 1, a current phase angle detecting relay 23
Is connected to the network current transformer 21, and the phase of the current passing through the network protector 14 is detected. That is, in the current phase angle detection relay 23, the phase angle of the current flowing into the load side 14 is 0 to π with respect to the network bus voltage.
It operates when there is a delay of / 2, and its operation signal is input to the control circuit 24. On the other hand, the network relay 21 operates when it detects that reverse power flows from the load side to the network bus 13, and the operation signal is input to the control circuit 24.

FIG. 2 is a circuit diagram of the control circuit 24. When the current phase angle detection relay 23 operates, the contact 23a is closed and input to the AND circuit 26 via the NOT circuit 25. That is, when the phase angle of the current flowing into the load side 14 is a delay of 0 to π / 2 with respect to the network bus voltage (when the load current is in the fourth quadrant on the polar coordinates), AN
The logical value “0” is output to the D circuit 26. From this,
When the inrush current (load current) is outside the fourth quadrant on the polar coordinates, the AND circuit 26 outputs the logical value "1".

On the other hand, when the network relay 21 operates, the contact 21a is closed and input to the AND circuit 26 via the timer 27. The timer 27 is set with a confirmation time limit for absorbing variations in the operation of the network relay 21. This confirmation time period is for the interruption lock of the protector circuit breaker 15 of all lines by regenerative electric power such as a motor load. That is, the network relay 21
When the operating state of (1) continues for a predetermined time or longer determined by the timer 27, the logical value "1" is output to the AND circuit 26.

Therefore, the control circuit 24 determines that the current phase angle detecting relay 23 is inactive (when the load current is in the fourth quadrant on the polar coordinates) and the operating state of the network relay 21 continues for a predetermined time period or longer. The protector breaker 15 will be opened.

FIG. 3 is a characteristic diagram of the closing area and the breaking area of the protector circuit breaker 15 according to the embodiment of the present invention. The characteristics of the current phase angle detection relay 23 are added to the operation characteristics of the network relay 21 shown in FIG.
When the phase angle of the load current is delayed by 0 to π / 2 with respect to the network bus voltage Vn (when the load current is in the fourth quadrant on the polar coordinates), the cutoff region is excluded.

That is, in order to prevent erroneous disconnection due to the load inrush current It, the disconnection detection characteristic curve S2 of the network relay 21 goes from the second quadrant of the polar coordinates to the fourth quadrant, and the line lags behind the origin by π / 2 (vertical axis). The characteristics are in line. As a result, even if the load inrush current It becomes large, it does not enter the cutoff region E2.

When the load inrush current It is in the fourth quadrant on the polar coordinates, the current phase angle detecting relay 23 operates, so that the contact 23a is closed and the output of the NOT circuit 25 becomes the logical value "0", while the inrush When the current (load current) is not in the fourth quadrant on the polar coordinates, the current phase angle detection relay 2
No. 3 remains inoperative and the contact 23a is opened, and NO
The output of the T circuit 25 has a logical value "1".

The protector is shut off by an AND condition between the output of the contact 23a and the logical value via the NOT circuit 25 and the logical value after the reverse power confirmation time limit determined by the timer 27 for closing the contact 21a when the reverse power of the network relay 21 is detected. Since the circuit breaker 15 is cut off, it is possible to prevent the protector circuit breaker 15 from being accidentally cut off due to the load rush current.

In the above description, the current phase angle detecting relay 2 is used.
3 is provided to obtain the characteristic of excluding the cutoff region when the load current is in the fourth quadrant on the polar coordinates. However, the load inrush current It is obtained by vector combination of the load inrush current It and the current of the phase advance capacitor. It is also possible to prevent erroneous disconnection due to.

FIG. 4 is a circuit diagram of the control circuit 24 when the phase advancing capacitor is turned on to the load side when the network relay 21 operates. As shown in FIG. 4, when the network relay 21 operates, the contact 21a of the network relay 21 closes and the phase advancing capacitor is turned on to the load side. On the other hand, the operating state of the network relay 21 is input to the timer 27, and the protector breaker 15 is opened when it continues for a predetermined time or longer.

FIG. 5 shows the vector combination of the load inrush current It and the phase advance capacitor current Ic in the network relay 21.
FIG. 10 is a characteristic diagram shown in the operating characteristic diagram of FIG. As a result, the vector combined current Is does not enter the cutoff area E2 of the network relay, and erroneous cutoff can be prevented.

As described above, when the phase advancing capacitor is turned on, when reverse power (current) of the network relay 21 is detected, a network for shutting off the protector circuit breaker 15 of all lines by regenerative power such as a motor load. Utilizing the confirmation time limit for absorbing the variation in the operation of the relay 21, the phase advancing capacitor is turned on before the confirmation time limit by the timer 27 elapses. That is, the reverse power detection signal of the network relay 21 due to the load inrush current It (21a is closed)
Then, the phase advancing capacitor is turned on to prevent erroneous cutoff by the phase advancing capacitor current before the confirmation time limit by the timer 27 elapses.

[0027]

As described above, according to the present invention, it is possible to prevent erroneous disconnection of the protector circuit breaker due to the load rush current caused by the characteristics of the network relay. Also,
The prevention of erroneous disconnection due to the load inrush current is not performed with the time-delayed characteristic during the period when the load inrush current is occurring.
It does not prevent the establishment of the network protection disconnection protection coordination.

[Brief description of drawings]

FIG. 1 is a system diagram of a network power distribution system to which a network protector according to an embodiment of the present invention is applied.

FIG. 2 is a circuit diagram of a control circuit according to an embodiment of the present invention.

FIG. 3 is a characteristic diagram of a closing area and a breaking area of the protector circuit breaker according to the embodiment of the present invention.

FIG. 4 is a circuit diagram of a control circuit when a phase advancing capacitor is turned on to the load side when the network relay according to the embodiment of the present invention operates.

FIG. 5 is a characteristic diagram showing vector composition of a load inrush current and a phase advance capacitor current in an operation characteristic diagram of the network relay according to the embodiment of the present invention.

FIG. 6 is a system diagram of a conventional network power distribution system.

FIG. 7 is an operation characteristic diagram of a conventional network relay.

[Explanation of symbols]

11 ... Load transformer, 12 ... Take-off circuit breaker, 13 ... Network busbar, 14 ... Network protector, 15
… Protector breaker, 16… Transducer current transformer,
17 ... Network transformer, 18 ... Load disconnector, 19 ...
Meter transformer, 20 ... Phase comparison relay, 21 ... Network relay, 22 ... Network current transformer, 23 ... Current phase angle detection relay, 24 ... Control circuit, 25 ... NOT circuit,
26 ... AND circuit, 27 ... Timer

Claims (2)

[Claims] 1. A network protector for protecting the load side of a network power distribution system, wherein power is supplied from a plurality of high-voltage distribution lines to a network bus, and further power is supplied from the network bus through a protector breaker to the load side. , A current phase angle detection relay that operates when the phase angle of the current flowing into the load side is a delay of 0 to π / 2 with respect to the network bus voltage, and that reverse power flows from the load side to the network bus line. A network comprising a network relay for preventing and a control circuit for opening the protector breaker when the current phase angle detection relay is inoperative and the operating state of the network relay continues for a predetermined time period or longer. Protector. 2. A network protector for protecting the load side of a network power distribution system, wherein power is supplied from a plurality of high-voltage distribution lines to a network bus and further power is supplied from the network bus to a load side via a protector breaker. , A network relay that prevents reverse power from flowing from the load side to the network bus, and a phase advancing capacitor is turned on to the load side when the network relay operates and the operating state of the network relay continues for a predetermined time or longer. And a control circuit that opens the protector circuit breaker when the network protector is opened.