JPH0231948A - Direct current feeding system - Google Patents

Abstract

PURPOSE:To prevent the erroneous cutting off of a solid current breaker caused by the charging/discharging of a capacitor and enable the setting of a cut-off current to a low current zone by separating the base resistance of a rectifier from a system at the time of the stoppage of the rectifier for feeding a DC power. CONSTITUTION:A switch 13 is controlled to be on during the operation of a thyristor rectifier 11 while to be off during the stoppage thereof. By turning off the switch 13 during the stoppage of the rectifier 11, even if a feeder 27 is fed from another substation, the route of a capacitor 23, a resistance 24, and a resistance 12 is removed and the capacitor 23 will not be charged. Although the switch 13 is on during the operation of the rectifier 11, the potentials on the rectifier side of a solid DC breaker 21 and the feeder side are nearly equal to each other due to the operation of the rectifier 11, without charging the capacitor 23. Thus, the capacitor 23 will not be charged preventing the discharged current of the capacitor 23 from flowing at the time of turning on the solid DC breaker 25.

Description

[Detailed description of the invention] (Purpose of the invention) (Industrial application field) The present invention relates to a DC feeding system for electric railways.

(Prior Art) Solid state DC interrupters are increasingly being used in DC feeding systems for electric railways. A conventional DC feeding system using a solid state DC interrupter is shown in Figure 2. In FIG. 2, 11 is a rectifier that converts AC power into DC power and supplies DC power to the wire, and 12 is a base resistor that allows base current to flow through the rectifier 11. Reference numeral 21 indicates a solid-state DC interrupter that switches on and off the DC power supplied to the feeder line, 22 indicates a turn-off thyristor constituting the solid-state DC interrupter, 23 indicates a capacitor 24 of the snubber circuit of the turn-off thyristor 22, and 25 indicates a solid-state DC interrupter. A solid DC interrupting device having the same configuration as 21 and opening/closing the regenerated power from the electric wire, 26 is a diode, and 27 is a feeder line.

Normally, power from the rectifier 11 is supplied to the feeder line through a solid state DC interrupter 21. When a short circuit or an overload occurs on the feeder line and an overcurrent flows through the solid-state DC cut-off device 21, this is detected and the solid-state DC cut-off device 21 shuts off. Similarly, when an overcurrent flows through the solid state DC cutoff device 25, this is detected and automatically cut off.

(Problem to be Solved by the Invention) In the feeder line system as described above, when the rectifier 11 is stopped and power is being fed by a rectifier connected to the same feeder line in another substation, the solid DC interrupter 21 The voltage on the rectifier side is almost Ov, and the voltage is established on the wire side. Therefore, the capacitor 2 of the snubber circuit of the solid DC interrupter 21
3 is charged through the resistor 24 and the base resistor 12 in a direction with the feeder line side being positive.

Here, when the solid-state DC interrupter 25 for regeneration is turned on, the charge in the capacitor 23 is discharged through the diode 26 and the solid-state DC interrupter 25. Since the inductance and resistance of the circuit are small, this discharged N current has a value equal to or larger than the current flowing through a normal solid state DC interrupter.

Therefore, even though there is no abnormality in the feeder wire, this current is detected and the solid state DC interrupter 25 interrupts the current.

As mentioned above, since the regenerative solid-state DC interrupter 25 is interrupted by the discharge current of the capacitor 23 of the snubber circuit, there is a problem in that the setting of the interrupting current of the solid-state DC interrupter 25 cannot be reduced. Ta. For this reason, the system had to withstand less than this breaking current, which was very uneconomical.

As described above, the object of the present invention is to provide a DC feeding system that prevents erroneous shut-off of a solid-state DC interrupter due to charging and discharging of a capacitor and allows setting of the interrupting current down to a low current range.

[Structure of the invention]

(Means for Solving the Problems) The present invention is to disconnect the base resistance of the rectifier from the system when the rectifier that supplies DC power is stopped.

(Function) According to the present invention, by disconnecting the base resistor when the rectifier is stopped, there is no charging path for the capacitor of the solid DC interrupter. The capacitor is not charged to the wire voltage, and there is no possibility of erroneous shutoff of the regenerative solid-state DC interrupter due to discharge of the capacitor. When the rectifier is in operation, the electric wire side and the rectifier side of the solid-state DC breaker have almost the same potential, so the capacitor is not charged and the solid-state DC breaker does not disconnect erroneously.

(Example) An example of the present invention is shown in FIG. Components that are the same as in FIG. 2 are numbered the same. 13 is the base resistance 12
This is a switch that opens and closes the

In FIG. 1, a switch 13 is controlled to be turned on when the rectifier 11 is in operation and turned off when the thyristor rectifier 11 is stopped. By turning off the switch 13 while the rectifier 11 is stopped, even if the feeder line 27 is fed from another substation, the path between the capacitor 23, the resistor 24, and the resistor 12 is eliminated, and the capacitor 23 will not be charged. . Further, while the rectifier 11 is in operation, the switch 13 is turned on, but since the rectifier 11 is in operation, the rectifier side and the wire side of the solid-state DC interrupter 21 have almost the same potential, and the capacitor 23 is not charged. .

As described above, in the configuration shown in FIG. 1, the capacitor 23 is not charged and no discharge current of the capacitor 23 flows when the solid state DC interrupter 25 is turned on.

Note that a series circuit of a capacitor and a resistor is connected in parallel to the rectifier element as a snubber circuit.

The aforementioned charging current of capacitor 23 flows through this snubber circuit. However, the capacitor of the thyristor's snubber circuit has a smaller capacitance than the capacitor 23 of the GTO's snubber circuit, and therefore the charging voltage of the capacitor 23 of the GTO's snubber circuit is the charging voltage of the snubber capacitor of the thyristor rectifier. Since the capacitor 23 of the GTO snubber circuit is smaller than that of the capacitor 23, the capacitor 23 of the GTO snubber circuit is not charged up to the voltage of the feeder line. Normally, the capacitor 23 of the GTO sniver circuit, which is smaller than the voltage of the snubber capacitor of the thyristor rectifier, is not charged to the voltage of the feeder line. Compared to the snubber capacitor voltage of a normal thyristor rectifier, the voltage of the capacitor 23 of the GTO snubber circuit is 1710-1720 or less. Therefore, the discharge current of the capacitor 23 of the GTO snubber circuit is very small and does not pose a problem.

Although the embodiment of FIG. 1 has been described using a switch, the effect remains the same even if a semiconductor switch such as a circuit breaker or a turn-off thyristor is used instead of the switch. Furthermore, although the turn-off thyristor has been described as a component of the solid-state DC interrupter, the effects of the present invention are the same even if the turn-off thyristor is used as a component of the solid-state DC interrupter.

〔Effect of the invention〕

As explained above, according to the present invention, the capacitor 23 of the snubber circuit of the heavy-duty solid-state DC interrupter 21 is not charged. Therefore, when the solid state DC interrupter 25 for regeneration is turned on, there will be no erroneous interrupt due to the discharge current of the capacitor 23. Therefore, it is possible to set the interrupting current down to a low current range, and a highly reliable DC feeding system can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a DC feeding system according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional DC feeding system. 11...Thyristor rectifier 12...Base resistor 13...Switch 21...Solid DC interrupter 22...Turn-off thyristor 23...Capacitor 24...Resistor 25...Solid DC interrupter 26 ...Diode 27...Feeder line agent Patent attorney Rule Yudo Ken Chika Ken Daishimaru Figure 1

Claims (1)

[Claims] A rectifier that supplies DC power to the feeder line, a solid state DC breaker device connected between the rectifier and the feeder line to interrupt fault current, and a regenerative device connected in antiparallel to the solid state DC breaker device via a diode. In a DC feeding system consisting of a solid DC breaker device and a series circuit of a switch and a base resistor connected in parallel to the rectifier, the switch is turned on when the rectifier is in operation, and the switch is turned on when the rectifier is stopped. A DC feeding system characterized by being turned off.