JPS59117027A - Dc 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 Application of the Invention] The present invention relates to a line-rechargeable DC breaker, and particularly to a DC breaker suitable for overall power flow reversal control.

[Prior art]

The prior art will be explained based on FIGS. 1 to 4.

FIG. 1 is a circuit diagram showing an overall power flow reversal control system (hereinafter referred to as power flow reversal control), and FIG. 2 is an operation example.

Normally, the DC system is on the AC side) The converter 2 converts it into DC (or vice versa) via the transformer 1, and then converts the DC to AC (or vice versa) via the line with another converter 3 (or vice versa). to supply electricity. Although the figure shows an example of two-terminal power transmission, it also shows an example in which a DC cutoff device 1o is provided on the line in consideration of multi-terminal power transmission. The control method shown in the figure is based on the method of switching the current margin Δ, and the DC current setting value I
With 4F applied to both converters, the current margin changeover switch 5 can be switched to the I or ■ side to reverse the current. Both converters are provided with constant current control circuits 6, 7 and phase control circuits 8, 9, respectively, to control the line current I.
An example of operation in which d, Idp, and ΔId are compared is shown in FIG. '2. Before reversal (line voltage is positive polarity), Iap shown by operating characteristic I is applied to the converter 2 side, and Idp - ΔId shown by operating characteristic ■ is applied to the converter 3 side, and it is operated at the operating point of the intersection A. There is. If overall power flow reversal control is to be performed, it can be achieved by switching the current margin changeover switch 5 to the I side. As is clear from the operating characteristics after inversion (line voltage is negative polarity) in Figure 2, the operating characteristic Idp - ΔId shown by I is added to the converter 2 side, and Iap shown by operating characteristic ■ is added to the converter 3 side. , is operated at the operating point of the intersection B. That is, the overall power flow reversal control is performed by switching the current margin changeover switch 5.

FIG. 3 shows an example of the configuration of the DC breaker device 10 shown in FIG. and glue handle hole 1 closing switch 12 for cutting off direct current, nonlinear resistance (for example, zinc oxide resistance) for overvoltage suppression and energy absorption of the breaker.
It consists of Figure 4 shows an example of the waveforms of line current i and line voltage V at the time of power flow reversal, where the line current is constant and
Only the polarity of the line voltage is reversed between times Ts and Tz. Generally, this time is about 0.2 to 0.5 seconds. If the charging resistance is chosen to be a small value, taking into consideration the high-speed reclosing of the circuit breaker, the charging voltage of the capacitor≠jisa will be equal to the voltage waveform shown in Figure 4, and a ground fault will occur during the current reversal. However, when cutting off the line current, the charging voltage of the capacitor was too small to cut off the line current. Furthermore, if a high charging resistance is selected, the charging/discharging time of the capacitor C becomes longer, and the polarity of the charging voltage of the capacitor differs from the polarity of the line voltage after the current flow is reversed. In this case, the polarity of the capacitor can also be switched by operating a disconnector. However, in connection with the control method, there was a need for a method that could cut off the power without any problems even in the event of an accident during a reversal of the current.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reliable DC breaker that can be disconnected without any trouble even when the polarity of the line voltage is reversed.

[Summary of the invention]

Focusing on the fact that power flow reversal control is performed by switching the current margin, the present invention provides a disconnector that obtains a signal directly or indirectly from the current margin changeover switch and inverts the polarity of the capacitor using this signal. It is characterized by a switching operation.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. Third
Items with the same functions as those in the figure are indicated by the same numbers. Switches 13 and 14 for reversing the polarity of the capacitor are provided at both ends of the charging capacitor C, and are connected to the operating device 15 at multiple contacts a and a' or contacts a and b'. Contacts a and b' and contact a' are connected externally, and a charging resistor r is connected between contact a' and the ground, and a reactor L and a closing switch 12 are connected in series between contact a' and one end of the commutation breaker. Form an LC oscillating current circuit. The operating unit 15 operates by delaying the signal from the current margin changeover switch 5 with a delay device 16. An example of operation is shown in FIG.

Now, when the current margin changeover switch 5 is connected to the ■ side and ΔId is applied to one converter, when the current margin changeover switch 5 is changed to the I side to perform power flow reversal control, this switching signal is transferred to the delay device. 16, the switch 15 is operated after delaying by 11, and t2 is the switch 13.
operation time. If the charging resistor has a high resistance, the terminal voltage V of the capacitor C will be as shown by the chain line in Figure 6. Depending on the selection of the delay time tl, the terminal voltage of the capacitor will always have the same polarity as the line voltage. This has the effect of preventing a decrease in v.

FIG. 7 shows another embodiment, in which the charging resistor r' is made small and responsibilities such as high-speed reclosing are taken into account. Contacts a and b are connected to the capacitor selector switch 17 and 18.
, c, a', b', and c' are provided, and an operating device 19 that switches from contacts a and a' to contacts b' and an operating device 21 that switches from contacts b' to contacts C and C' are used to connect the capacitor. An example of the operation is shown in FIG. 8. In this case, the current margin changeover switch 5 is switched by a signal from the operating device 19, and when performing power flow reversal control,
First, operate the operating device 19 to close contact a.

Switch from a' to contact b/.

This switching signal is passed through the delay device 20 from the auxiliary switch linked with the operating device 19 to t! The current margin change-over switch 5 is switched from the ■ side to the I side with a delay of 10 seconds to perform power flow reversal control. After the power flow is reversed, the switch is contacted by a signal delayed by t2 through the delay device 22 compared to the signal before the power flow is reversed.

It is connected to the line by switching from b' to contacts c and c'.

According to this configuration, the capacitor is disconnected from the line before the current is reversed, and after the current is reversed, the polarity of the capacitor is reversed and connected to the line, which has the effect of preventing a drop in the charging voltage of the capacitor.

FIG. 9 is a preliminary configuration example showing another embodiment.

In the figure, a grounding disconnection section 23 is provided between the switch 14 and the charging resistor r', and a capacitor C
and open/close operations between the top and bottom. FIG. 10 shows an example of operation. When the current is reversed, operate the capacitor switching controller 15 and the controller 24 of the grounding disconnector 23 to disconnect the capacitor C from the line, and then switch the stain flow margin switching switch using a signal delayed by the delay device 26. 5 is switched from the ■ side to the 1 side to perform power flow reversal control. In this case, during the current reversal, the switches 13, 14 switch from contacts a and a' to contacts b' and reverse the polarity of the capacitor C. However, since the ground side disconnector 23 is in an open state, the charging voltage of the capacitor C does not decrease and is maintained at the line voltage before the current reversal. After the power flow is reversed, the operating device 25 of the ground side disconnector is operated by a signal delayed by the multi-delay device 27 than the switching signal of the current margin changeover switch 5 at the time of power flow reversal, and the disconnector 23 is closed. With the polarity reversed, it is connected to the negative polarity line and returns to normal operation. According to this embodiment, even if the value of the charging resistor r' is reduced to satisfy the requirements such as high-speed reclosing, the grounding side disconnector is opened to prevent a drop in the charging voltage, and the capacitor is Because the polarity can be switched, even in the event of an accident during power flow reversal, the current can be commutated by turning on the closing switch 12, and the current can be cut off by opening the circuit breaker 11), making it possible to create a reliable DC breaker. Can be provided.

In implementing the present invention, other closing means such as a gap may be used in place of the closing switch 12, and a current margin switching switch is used as a polarity reversal signal of the line voltage, but the constant voltage control device of the converter It is possible to use an accompanying signal that is used to determine the output value, etc., of an accident.

〔Effect of the invention〕

As described above, according to the present invention, the reliability of the DC breaker can be improved because the line voltage can be cut off without any problem even when the polarity of the line voltage is reversed.

[Brief explanation of the drawing]

Fig. 1 is a circuit configuration diagram illustrating an example of power flow reversal control, Fig. 2 is a characteristic diagram illustrating an example of the operation of Fig. 1, Fig. 3 is a circuit configuration diagram of a DC breaker illustrating a conventional technique, and Fig. 4 3 is a characteristic diagram showing the operation example of FIG. 3, FIG. 5 is a circuit configuration diagram of a DC breaker showing an embodiment of the present invention, FIG. 6 is a characteristic diagram showing the operation example of FIG. 5, and FIG. 7 is a characteristic diagram showing the operation example of FIG. , FIG. 9 is a circuit configuration diagram of a DC breaker explaining another embodiment of the present invention, FIG.
FIG. 0 is a characteristic diagram showing an example of the operation of FIGS. 7 and 9. 5... Current margin switching switch, 11... Commutation breaker, 12... Closing switch, 13, 14, 17
゜18...Capacitor polarity switch, 15, 19
゜21... Capacitor polarity switching operator, 16, 20
゜22...Delay device, r...Charging resistor, L...Reactor, C...Charging capacitor. Fig. 1 △Work〆 Work dLP Fig. 3 Military 4-Fig. 0 9th Fig. IO mouth, W<

Claims (1)

[Scope of Claims] 1. A DC breaker configured by connecting a series circuit of a line charging capacitor, a reactor, and a closing means connected to a line of a DC transmission system in parallel to a commutation breaker. A DC breaker comprising a polarity reversal connection device that connects the charging capacitor to the line with the polarity reversed when the polarity of the charging capacitor is reversed. 2. The DC breaker according to claim 1, wherein the polarity reversal connection device is operated by a signal from a current margin changeover switch. 3. In the device described in claim 1 above, the polarity reversal connection device has a polarity switching switch on both sides of the charging capacitor, and the bipolar switching switch has a polarity switching switch on each side of the charging capacitor. A DC breaker comprising: a movable element connected to one end of the charging capacitor; and at least two stators connected to both end lines of the charging capacitor and capable of switching connection to the movable element.