JP2524134Y2 - DC feed system protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention relates to a protection device for a DC feed system in a DC electric railway.

B. Summary of the Invention The present invention relates to a DC feed system for feeding a feeder from a first and a second DC substation adjacent to each other. Between the first undervoltage relay and
A second under-voltage relay is provided between the rail located at the installation location of the relay and the ground, and at least one of the under-voltage relays is operated between the first and second DC substations and the feeder line. By connecting and disconnecting each of the circuit breakers, the feeder line can be protected by an inexpensive and simple device.

C. Prior Art A DC feed system in a DC electric railway is constructed, for example, as shown in FIG. In FIG. 3, reference numerals 1 and 2 denote feeders for ascending and descending, respectively. Output powers of rectifiers 3 and 4 of the first and second DC substations adjacent to each other are supplied to these feeders 1 and 2 via DC high-speed circuit breakers 5, 6, 7, and 8, respectively. Reference numeral 9 denotes a rail connected between the negative electrodes of the rectifiers 3 and 4.

In the system configured as described above, protection against short circuit of the feeder, ground fault, and the like is performed by monitoring the current at each end of the feeder. That is, as shown in the figure, the current detector 1 provided at the outlet of the feeders 1 and 2 for each direction
1a, 11b, 11c, and 11d detect the current flowing through the feeders 1 and 2, and detect the normal current (start-up) by detecting devices 12a, 12b, 12c, and 12d including a ΔI-type relay, a current change rate relay, and an overcurrent relay. Current (including current) or an accident (short circuit) current, and if it is an accident (short circuit) current, the DC high-speed circuit breakers 5, 7 (or DC high-speed circuit breakers 6, 8) are disconnected. It is a hurry.

D. Problems to be Solved by the Invention The protection device for the DC feed system as described above needs to discriminate between the starting current and the fault current, and thus combines a ΔI type relay, a current change rate relay, an overcurrent relay, and the like. And a communication cutoff device (not shown) is also required. Therefore, when power is supplied to both the upper and lower lines as shown in FIG. 3, four sets of protection devices are required. Therefore, there are drawbacks in that the protection device becomes large in size, becomes heavy equipment, and becomes very expensive.

The present invention has been made in view of the above points, and an object of the present invention is to provide a protection device for a DC feed system which can reduce the cost of the device and simplify the device configuration.

E. Means for Solving the Problems The present invention is directed to a DC feed system for feeding power from a first and a second DC substation adjacent to each other to a feeder via a circuit breaker. (2) a first undervoltage relay provided between the ground and the feeder at the point where the feeder voltage is the lowest during steady-state feeding, among the feeders connecting the DC substation; A second undervoltage relay provided between the rail located at the installation location and the ground, and when at least one of the first undervoltage relay and the second undervoltage relay operates In addition, a circuit breaker provided between the first DC substation and the feeder line is disconnected from a circuit breaker provided between the second DC substation and the feeder line.

F. Action When a ground fault occurs between the feeder and ground, the voltage between the feeder and ground drops to approximately zero volts. Therefore, the first undervoltage relay operates, and the operation signal causes the breaker provided between the first DC substation and the feeder line and the circuit breaker provided between the second DC substation and the feeder line. Communication is cut off. This ensures that the feeder is protected from the ground fault.

Also, when a ground fault occurs between the rail and the ground, the voltage between the rail and the ground drops to substantially zero volt. For this reason, the second undervoltage relay operates, and the two circuit breakers are disconnected by the operation signal. This ensures that the feeder is protected from the ground fault.

When a short circuit occurs between the feeder and the rail, both the feeder-to-ground voltage and the rail-to-ground voltage decrease significantly. Therefore, the first and second undervoltage relays operate together, and the two circuit breakers are disconnected by the operation signal. This ensures that the feeder is protected from the short circuit.

At start-up, the feed-back current changes abruptly.
Since the voltage applied to each of the second undervoltage relays does not become lower than the set voltage of the relay, the first and second undervoltage relays do not operate by mistake. For this reason, there is no need to provide a current rate-of-change relay or the like for distinguishing the starting current from the fault current.

As described above, the first undervoltage relay operates when the feeder-to-ground ground fault occurs, the second undervoltage relay operates when the rail-to-ground ground fault occurs, and the second undervoltage relay occurs when the feeder-to-rail short circuit occurs. Since the first and second undervoltage relays operate, it is possible to easily determine whether the accident is a ground fault or a short circuit by knowing the operation state of each undervoltage relay.

G. Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the present invention. In FIG. 1, the same parts as those in FIG. 3 are denoted by the same reference numerals, and the description thereof will be omitted. When the power is supplied from the first and second DC substations (rectifiers 3 and 4), the undervoltage relays 21a, 21a, 21b are connected to each other. Undervoltage relays 22a and 22b are connected in parallel between the rail 9 located at the installation location of the undervoltage relays 21a and 21b and the ground. That is, if the outputs of the first and second DC substations adjacent to each other have the same capacity, they are provided at an intermediate point between the two substations as shown in the figure. Undervoltage relay 21a,
Diodes 23a to 23d having the illustrated polarities are connected in parallel to 21b, 22a, and 22b, respectively. The above-described current detectors 11a to 11d and detection devices 12a to 12d are omitted. Undervoltage relay
The operation setting voltages of the transistors 21a, 21b, 22a, and 22b are respectively set to values slightly lower than the voltages divided at the time of applying the minimum feed voltage, for example. When at least one of the undervoltage relays 21a and 22a is operated, the operation signal is used to disconnect and disconnect the DC high-speed circuit breakers 5 and 7 on the upstream feeder 1 side. Relays 21b, 22
When at least one of b operates, the operation signal disconnects the DC high-speed circuit breakers 6, 8 on the downstream feeder line 2 side. In order to cut off the communication as described above, the contact circuit of the undervoltage relay is configured as shown in FIG. 2, for example. That is, when the ascending feeders 1 side, a series circuit consisting of the normally closed contact 22 _ab normally open contacts 21 _aa and the relay 22a of the undervoltage relay 21a, the relay
The normally closed contact 21 _ab of the relay 21 a and the normally open contact 22 of the relay 22 a
_a series circuit consisting of _aa and a normally open contact 21 of the relay 21a.
_aa and a series circuit composed of the _normally open contact 22aa of the relay 22a are connected in parallel between the terminals 30 and 31, and when the terminals 30 and 31 are short-circuited, the DC high-speed circuit breakers 5 and 7 are disconnected. The downstream feeder 2 also forms a relay contact circuit in the same manner as in FIG.

In the device configured as described above, if a ground fault occurs between the up-feeder 1 and the ground, the undervoltage relay 21
The voltage across a drops to approximately zero volts, and the relay 21a operates. Then, the normally open contact 21 _aa of the undervoltage relay 21 a is closed, and the normally closed contact 22 _ab of the undervoltage relay 22 a remains closed, so that the terminals 30 and 31 are short-circuited, and the DC high-speed circuit breaker 5 is closed. , 7 is disconnected. This ensures that the feeder line 1 is protected from the ground fault.

When a ground fault occurs between the rail 9 and the ground, the voltage across the undervoltage relay 22a drops to substantially zero volt, and the relay 22a operates. Then, the normally open contact 22 _aa of the undervoltage relay 22 a is closed and the normally closed contact 21 _ab of the undervoltage relay 21 a is closed.
Remains closed, the terminals 30 and 31 are short-circuited, and the DC high-speed circuit breakers 5 and 7 are disconnected. This ensures that the feeder line 1 is protected from ground faults.

When a short circuit accident occurs between the feeder line 1 and the rail 9 (due to an internal short circuit of the train motor, etc.), the undervoltage relay 21a,
The voltage across each of the relays 21a and 22a is significantly reduced.
2a works together. Then, since the normally open contacts of the undervoltage relays 21a and 22a are both closed, the terminals 30 and 31 are short-circuited, and the DC high-speed circuit breakers 5 and 7 are disconnected. This ensures that the feeder line 1 is protected from the short circuit accident.

As described above, the circuit breakers 5 and 7 can be reliably shut off both at the time of a ground fault and at the time of a short circuit, and by monitoring which series circuit between the terminals 30 and 31 is closed, the feeder cable 1- A ground fault between the ground, a ground fault between the rail 9 and the ground, or a short circuit between the feeder line 1 and the rail 9 can be easily determined.

At the time of start-up, the feed-back current changes abruptly, but the voltages applied to the undervoltage relays 21a and 22a do not become lower than the set voltage of the relays.
a, 22a does not work. Therefore, there is no need to provide a current change rate relay, a ΔI type relay, an overcurrent relay, and the like for distinguishing the starting current from the fault current.

The above operation is exactly the same for the downstream feeder 2.

Here, the original purpose of electric railway is to run a train. Each train has its characteristic minimum operating voltage,
If the voltage falls below the regulation voltage, the train cannot be operated. Therefore, as in the present invention, even if the power supply to the feeder is stopped when the feeder voltage at the point where the voltage becomes the lowest in the steady state becomes lower than the lowest feed voltage, there is no adverse effect on the above-mentioned purpose.

H. Effects of the Invention As described above, according to the present invention, undervoltage relays are provided between the feeder line and the ground and between the rail and the ground at the point where the minimum feed voltage is obtained. Since the circuit breakers between the first and second DC substations and the feeder line are interrupted, the feeder line can be reliably protected from the accident even when a ground fault or short circuit occurs. In other words, it is very difficult to detect high-resistance ground faults in the protection of railway feeders, so in the past, for example, each substation was protected by detecting the negative electrode potential. Entanglement can be protected without blind spots.

In addition, since protection is performed by voltage detection, a ΔI type relay, a current change rate relay, an overcurrent relay, and the like for distinguishing and detecting a starting current and a fault current are not required, thereby simplifying the device configuration and reducing the cost of the device. Can be achieved.

Furthermore, whether only the first undervoltage relay has been activated,
Depending on whether only one of the undervoltage relays has been activated or both the first and second undervoltage relays have been activated.
It can be easily determined whether there is a ground fault between the ground, a ground fault between the rail and the ground, or a short circuit between the feeder and the rail.

[Brief description of the drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a circuit diagram showing the overall structure, FIG. 2 is a contact circuit diagram of a relay, and FIG. 3 is protection of a conventional DC feed system. It is a circuit diagram showing an example of a device. 1,2 ... feeder, 3,4 ... rectifier, 5,6,7,8 ... DC high speed circuit breaker, 9 ... rail, 21a, 21b, 22a, 22b ... undervoltage relay.

Claims (1)

(57) [Scope of request for utility model registration] 1. A DC feeder system for feeding power from a first and a second DC substation adjacent to each other to a feeder line via a circuit breaker, wherein the feeder line connects the first DC substation and the second DC substation. A first undervoltage relay provided between the ground and the feeder at the point where the feed voltage becomes the lowest during steady-state feeding; a rail positioned at the installation location of the first undervoltage relay and a ground; And a second undervoltage relay provided between the first DC substation and when at least one of the first undervoltage relay and the second undervoltage relay operates And a circuit breaker provided between the feeder and
A protection device for a DC feed system, wherein the DC feeder and the breaker provided between the feeder line are disconnected from each other.