JPH0212367B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to direct current and disconnection circuits, and particularly relates to arcless type DC and disconnection circuits used in fused power sources and DC power transmission. .

[Conventional technology]

Figure 3 shows, for example,
FIG. 1 is a schematic configuration diagram of a conventional direct current or disconnection circuit shown in Publication No. 12533. In this Figure 3,
1, a series circuit including a load 2 and a capacitor breaker 3 is connected between both ends of the DC power supply 1, and a series circuit including a switch 4, an inductor 5, and a capacitor power supply 6 is connected to the capacitor breaker 3. connected in parallel.

Further, FIG. 4 shows a waveform diagram of the current flowing through the sheath breaker 3 when the sheath disconnection operation is performed in the conventional direct current and disconnection circuit example shown in FIG.

The operation of the conventional example will be described below with reference to FIGS. 3 and 4. Now, at the moment
It is assumed that at _t1 , the breaker 3 is opened, and at the same time (at the time when the breaker 3 is opened by a predetermined stroke), the switch 4 is closed. At this time,
Depending on the polarity of the pre-charged capacitor power supply 6, if it is (-) polarity, it will be at time _t2 as shown in waveform i(-), and if it is (+) polarity, it will be as shown in waveform i(+). At time t ₂ ', the current I flowing through the shear breaker 3 becomes zero, and the intended shear breaker operation is carried out accordingly.
If the shearing at this time t ₂ or t ₂ ' ends in failure, the desired shearing will be repeated at the point in time when the current flowing through the sheath breaker 3 becomes zero in the next cycle. will be carried out. Note that the inductor 5 is used to adjust a time constant that defines the time from the opening of the shield breaker 3 until the current flowing through it becomes zero.

Conventional well-known direct current and disconnection circuits are constructed as described above, so that between the time when the breaker opens and the current flowing through the breaker becomes zero, the voltage between the electrodes of the breaker becomes zero. Arc plasma may be generated. This arc plasma damages the electrodes of the shield breaker, shortening its lifespan.

Furthermore, due to the presence of the arc plasma, even if the current flowing through the breaker becomes zero, at the next instant, the current tends to flow in the opposite direction, causing the breaker to break. There were problems such as the possibility of failure.

In view of the shortcomings of the known direct current and disconnection circuits, the present inventor has previously filed a patent application filed in 1983 by the applicant.
In No. 171795, we proposed an improved DC and disconnection circuit as shown in Figure 5.

In FIG. 5, 7 is a variable voltage DC power supply, which is connected to a load coil 13 through a series circuit consisting of a shield breaker 8 and a rectifier such as a diode 11. Furthermore, a series circuit consisting of a capacitor power supply 9 and a switch 10 and a shear breaker resistor 12 for absorbing energy are connected in parallel to the series circuit of the shear breaker 8 and the diode 11. A clover switch 14 is connected in parallel with the DC power supply 7, and a current sensor 15 is provided to detect the current of the disconnector 8. In addition, the series circuit consisting of the capacitor power supply 9 and the switch 10 includes:
An inductor 16 is inserted as necessary. A command circuit 17 is connected to the current sensor 15,
The output signal from the command circuit 17 causes the breaker 8 to open and close.

Next, the operation of the circuit shown in FIG. 5 will be described with reference to FIG. 6, which shows operational waveforms of the DC and disconnection circuit shown in FIG. First, the DC power supply 7 is energized, and the current flowing through the load coil 13 is raised to a constant value (I ₁ ). At this time, the current flowing through the load coil 13 and the current flowing through the shrapnel breaker 8 are approximately equal to each other. This energization causes load coil 1 to
After a predetermined amount of energy has been stored in 3, the crowbar switch 14 is closed, the current flowing through the load coil 13 is crowbarred by the crowbar switch 14, and the DC power source 7 is disconnected from the circuit. That is,
For example, when a certain predetermined electrical energy is held in the load coil 13 by energization from a normal variable DC power source 7 such as a thyristor power source, at this point, the potential of the positive polarity DC power source 7 becomes zero. or its polarity is reversed to a value near zero. At this time, the clover switch 14 is closed at the same time, but as described above, since the potential of the DC power supply 7 is set to zero or a negative value close to zero, the electric potential from the DC power supply 7 to the clover switch 14 is closed. The electricity is almost gone,
Electricity is supplied mainly based on the electrical energy held in the load coil 13. The DC power supply 7 is thus substantially disconnected from the circuit.

Next, the switch 10 is closed at time _t3 due to the occurrence of a failure or the like, and the capacitor power supply 9 is closed.
A more transient current I ₂ begins to flow through the sheath breaker 8 in the opposite direction to the current I ₁ and decreases over time. Therefore, at time _t4 , the difference between both currents _I1 and _I2 becomes zero, but the current change rate at this time is within the range that can be withstood by the diode 11 connected in series with the circuit breaker 8. Generally, the time difference between time t ₄ and time t ₃ is extremely short.

Then, at time _t4 , the current sensor 15 senses that the current flowing through the shield breaker 8 has become zero, and the command circuit 17 gives an opening command signal to the shield breaker 8. At time t ₅ after a certain delay time, the shroud breaker 8 is opened. At this time, since no current is flowing through the shingle breaker 8, arc plasma is not generated between the electrodes of the shingle breaker.

[Problem that the invention seeks to solve]

The above-mentioned conventional DC and disconnection circuits developed earlier by the present inventor have various advantages, but after successful disconnection, a voltage drop occurs in the resistor 12 due to the discharge current from the capacitor power supply 9. However, there was a problem in that the capacitor power supply 9 was reversely charged by the voltage generated across the disconnector.

This invention was made in order to solve the above-mentioned problems, and it is possible to disconnect the insulation in a short time without damaging the insulation breaker electrode, and to use a direct current that can protect the capacitor power supply. The purpose is to obtain a circuit breaker.

[Means for solving problems]

In the direct current or disconnection circuit according to the present invention, a series circuit of a shield disconnector and a rectifying element is provided between a DC power source and a load, and a series circuit of a capacitor power source and a switch is provided in parallel with this series circuit. In addition,
A bypass switch is provided in parallel to the capacitor power supply.

[Effect]

According to this invention, by closing a switch connected in series with the capacitor power supply, the current flowing from the capacitor power supply makes the current flowing to the capacitor breaker zero, and this zero current is detected and the capacitor breaker is activated. Open and perform the cutting operation without arcing. In the event of a power outage, the capacitor power supply is shorted using a bypass switch to prevent reverse charging.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a direct current or disconnection circuit according to the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of the above embodiment, and
FIG. 2 shows a waveform diagram of the breaker current in the above embodiment.

First, in Fig. 1, the differences from Fig. 5 are as follows.
A break resistor 12 is inserted into the discharge circuit of the capacitor power supply 9, and a voltage detection circuit 19 and a bypass switch 20 are connected in parallel to the capacitor power supply 9. The voltage detection circuit 19 is a bypass switch 20
It is now possible to control opening and closing. The other parts or elements are the same as those shown in FIG. 5, so their explanation will be omitted.

Next, referring to FIG. 2, the operation of the above embodiment shown in FIG. 1 will be explained. still,
The waveform diagram in FIG. 2 is basically the same as that in FIG. 6.

First, the DC power supply 7 is connected to the load coil 13 and energized to excite it. This load coil 1
When the voltage of the DC power supply 7 is lowered after the current flowing through the switch 3 reaches a certain value (I ₁ ), due to the action of the crowbar diode or switch 14,
A constant current flows within the time constant range set for the circuit consisting of the diode 11, the breaker 8, the load 13, and the switch 14, and the DC power source 7 is disconnected from the load coil 13.
At this time, the current flowing through the load coil 13 is equal to the current I ₁ flowing through the disconnector 8, and thus energy is stored in the load coil 13.

Next, at time t ₃ when a failure occurs, the second switch 10 is closed by an external command, and current I ₂ flows from the pre-charged capacitor power supply 9 to the disconnector 8 . The direction of this current I ₂ is opposite to the current I ₁ that previously flowed through the sheath breaker 8, so that the entire sheath breaker current I ₁ - I ₂ at time t ₃
It starts to decrease more and reaches zero at time t ₄ . In FIG. 2, the dotted line represents the current waveform when the diode 11 is not inserted in series with the breaker 8 and the breaker 8 is kept closed, and from time t ₄ to t _5.
The current takes a negative value during this time and becomes zero again at time _t5 , but if diode 11 is inserted,
The short-circuit current does not reverse as shown by the dotted line, and the period T is determined by the charging/discharging circuit constants of the capacitor power supply 9.
A zero current value is maintained throughout. The current sensor 15 detects this zero current value, and the command circuit 17
A command is given to open the disconnector 8. Therefore, during this period T, no current flows through the breaker 8, so even if the breaker 8 is opened, no arc plasma is generated between the breaker electrodes. When a voltage is generated between the electrodes of the breaker 8 due to the complete sintering operation, the gap between the electrodes has widened, so there may be no arc plasma. The disconnector 8 can have a high dielectric strength voltage. The operation up to this point is the same as in the case of FIG.

On the other hand, the capacitor power supply 9
is going to be charged in the reverse direction through the resistor 12, the load 13, the switch 14, the second switch 10, and if necessary the inductor 13.
, and before the reverse voltage is detected, a command signal is sent to the bypass switch 20 to close it, and the capacitor power supply 9 is short-circuited to prevent reverse charging, and the current is attenuated through the shrunken resistor 12 to completely eliminate the voltage. You can make a decision.

In the above embodiments, the case where a coil is used as the load has been described, but the present invention is not limited to this, and the same effect can be achieved even when a load resistor is used. However, in this case, the sheath breaking resistor 12 is no longer necessary. Furthermore, since stray inductance is normally included, the inductor 13 may be removed by adjusting the time constant.

Furthermore, since the electrode of the shield breaker 8 is generally moved mechanically, if it takes a predetermined amount of time to reach the open state after the open signal is input, the Alternatively, an open signal may be input. In other words, depending on the occurrence of a malfunction, etc.,
Give an open signal _to
2nd switch 1 earlier by the time corresponding to the time of t ₄
0 may be opened. In this case, current sensor 15 is not necessary. In addition, if the second switch 10 also requires a predetermined delay operation time, the second switch 10
The switch 10 may also be commanded to operate in advance.

〔Effect of the invention〕

As explained above, in the DC and disconnector circuits according to the present invention, when the switch is closed, the current flowing through the disconnector is reduced to zero by the current flowing from the capacitor power supply, and this zero current is detected. The capacitor power supply is short-circuited by a bypass switch during the power cutoff operation, which prevents the capacitor power supply from being charged with reverse voltage and prevents damage to the capacitor power supply. .

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of a direct current and disconnection circuit according to an embodiment of the present invention, Fig. 2 is a waveform diagram of the disconnection current of the above embodiment, and Fig. 3 is a diagram of a conventional known direct current and disconnection circuit. 4 is a waveform diagram of the conventional breaker current shown in FIG. 3, and FIG. 5 is a conventional direct current and breaker circuit according to the applicant's previous application. and FIG. 6 is a waveform diagram of the DC current and disconnection current of the disconnection circuit shown in FIG. 7...DC power supply, 8...Clip breaker, 9...Capacitor power supply, 10...Switch, 11...Rectifying element, 12...Clip resistance, 13...Load, 15...
...Current sensor, 17...Command circuit, 19...Voltage detection circuit, 20...Bypass switch. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In a direct current or disconnection circuit that performs direct current or disconnection using a disconnector provided between a DC power source and a load, a rectifier connected in series with the disconnector element,
A series circuit of at least a capacitor power supply and a switch connected in parallel to a series circuit of a capacitor and a rectifying element, detects when the current flowing through the capacitor and the switch becomes zero, and and a means for detecting a reverse voltage of the capacitor power supply and short-circuiting the capacitor power supply, the current zero state being a predetermined condition based on the operation of the rectifying element. A direct current or disconnection circuit characterized by being maintained over a period of . 2. The means for issuing an open command includes a current sensor that detects the shroud breaker current, and a command circuit that outputs an open command signal to the shunt breaker when the sensor detects a zero shunt breaker current; A direct current or disconnection circuit according to claim 1, comprising: 3. The shorting means is connected to both ends of the capacitor power supply and generates a short circuit command signal of the capacitor power supply when the reverse voltage is detected, and a voltage detection circuit that is connected to both ends of the capacitor power supply and generates a short circuit command signal of the capacitor power supply. A direct current or disconnection circuit according to claim 1 or 2, comprising a bypass switch that is closed by a bypass switch.