JPS6243021A - Automatic circuit breaker operator - 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 The present invention relates to an automatic disconnector operating device for high-speed opening of a disconnector.

When opening a disconnector, it is necessary to pay attention to the disconnecting ability of the disconnector. In general, a disconnector has the ability to cut off the transformer excitation current and short line charging current, but it does not have the ability to cut off the load current. Therefore, the opening operation is performed after thoroughly checking that there is no load current in the disconnector and the connection state, for example, the electric gap at both ends of the disconnector, and that no load is connected. When the disconnector is in a no-voltage state, that is, when the power supply is not connected, it is generally possible to open the disconnector, but
Immediately after disconnection from the power supply, if the charge accumulated in the stray capacitance of the transmission line is discharged by the transformer, load, etc. through the disconnector, this excess 'f! The disconnector opening operation must be prohibited until the tit flow is sufficiently attenuated.

This will be explained using the power system shown in FIG. 1 as an example.

In Fig. 1, 1 to 3 are circuit breakers, 4 to 11 are disconnectors, 12.13 is a power supply system or a generator, 14 is a load,
15 and 16 are underground cable transmission lines, and 17 is a transformer.

Now, suppose that an accident occurs in the cable 15 and the breaker 1.2 is tripped by the protective relay while the disconnector 7 is open and power is being supplied from the power source 112 to the load 14. The load 14 immediately performs a series of system switching operations to receive power supply from the power source 13, but first, the disconnector 6 must be opened in order to disconnect the fault location from the system. Judging from the connection state, there is no fault current or load current in the disconnector, so the conditions for opening the new circuit are met. However, for a while after the circuit breaker 1.2 trips, the stray capacitance of the cable as shown in Figure 2! 21, the inductance 22 and resistance 23 of the cable, and the zero-phase inductance 24 and resistance 25 of the transformer, a damping transient current 11 flows through the new circuit 6. This discharge current i may greatly exceed the breaking capacity of the disconnector, and after the breaker trips, the disconnector cannot be opened immediately, and can only be opened after this transient current becomes sufficiently small. This current usually disappears in a few seconds to 10 seconds, and conventional manual or manual activation (even if it is electric, it is started manually)
In some cases, this was done extremely slowly, requiring human judgment and telephone contact with other substations and power supply stations, and there was no need to pay attention to transient currents.

However, when a disconnector opening operation is performed by an automatic system operation device such as an automatic restoration device, a series of system operations are performed extremely quickly, so it has become necessary to pay attention to the above-mentioned current transient phenomenon. In addition, if there is no function to suspend the disconnector open operation command from the system automatic operation device for a certain period of time, the disconnector must open after a certain period of time after issuing the disconnector open operation signal to the system automatic operation device. For example, the disconnector opening operation signal is issued again, and this is repeated until the disconnector becomes open, which is undesirable.

The purpose of the present invention is to measure the disconnector current so as not to damage the contact part of the disconnector when the disconnector is opened due to transient current,
If the disconnector's breaking capacity is lower than -L, a command to open the disconnector is sent once, and the command is prevented from being issued again when the disconnector does not open.

The present invention will be explained in detail below.

FIG. 3 shows a practical example of the automatic disconnector operating device according to the present invention, in which 61 is an automatic disconnector operating circuit,
As this disconnector automatic operation circuit 61, each circuit shown in FIGS. 4 to 7 is used. Reference numeral 62 denotes an R-S flip-flop, which immediately issues a disconnector open operation command m to the disconnector automatic operation circuit 61 when the disconnector open operation command Q from the system automatic operation device is input to the set terminal S. This disconnector opening operation command l is shown as C in FIGS. 4 and 6, which will be described later.
This corresponds to i in FIGS. 5 and 7. 63 is an OR gate, and 64 is a timer circuit that is activated by a disconnector open operation command Q from the system automatic operating device and sends out an output n after a certain period of time T.

Next, the operation will be described. The disconnector open operation command Q from the system automatic operating device is input to the R-S flip-flop 62 and at the same time starts the timer circuit 64. The R-S flip-flop 62 immediately issues a disconnector opening operation command m to the disconnector automatic operation circuit 61.

The automatic disconnector operation circuit 61 outputs a disconnector open operation signal 0 when a predetermined condition is met. This disconnector opening operation signal 0 corresponds to d in FIGS. 4 and 6 and to k in FIGS. 5 and 7, which will be described later.

Either this disconnector open operation signal 0 is output, the disconnector open operation command Q is issued, and after a certain period of time T, the output n of the timer circuit 64 is output, or the hold release signal P is output from the system automatic operating device. If so, the signal q is input to the reset terminal R of the R-S flip-flop 62 and resets its output.

If the operation is performed as described above, if the disconnector does not open after a certain period of time after issuing the disconnector open operation signal to the system automatic operating device, the R-S flip-flop 62 will be reset, so the disconnector will be disconnected from now on. No inter-device operation signals are sent. Therefore, it is possible to avoid repeatedly sending out the opening operation signal until the disconnector is in the open state.

Next, specific examples of the automatic disconnector operation circuit 61 are shown in FIGS. 4 to 7.
Explain using diagrams.

FIG. 4 shows a first specific example of an automatic disconnector operation circuit, in which numeral 31 indicates the disconnector to be opened, which corresponds to the disconnector 6 in the above description. 32 is a sensor that is highly sensitive in a small current range and is installed at one end of the disconnector 31; 33 is a rectifier that receives the output obtained from the sensor 32 as an input and sends out a DC voltage a proportional to the effective value of the current; 34
is a comparator that determines whether the magnitude of the current of the disconnector is below the disconnector's breaking ability. Therefore, this comparator 34 compares the DC voltage a with the set value output e of the constant voltage circuit 36, and if a>e (the magnitude of the disconnector current is greater than or equal to the disconnector breaking capacity), the level is "L", e ＞
If a (the magnitude of the current of the disconnector is less than the disconnector's breaking capability), an "H" level signal is output. The disconnector open operation command C coming from the system automatic operating device is AND gate 3
5, when a>e, the opening operation signal d is not output. When e>a, the disconnector opening operation command C is not blocked by the AND gate 35, and the opening operation signal d is output. In addition, current detection related to the breaking ability of a disconnector is related to a very small current area compared to normal power flow.
It does not require a wide range like relays or current transformers for measurement, but requires high sensitivity in a small current range as a sensor. Also, the linearity of the sensor is not very important.

Next, in order to detect the size downstream of the disconnector, the peak of the output of the sensor 32 may be detected.
This will be explained using figures.

FIG. 5 shows a second specific example of the automatic disconnector operation circuit, and the same reference numerals are used for the same components as those in FIG. 4 or those having the same functions. In the figure, since the discharge current flowing through the disconnector 31 is generally oscillatory, the output g of the sensor 32 is an alternating current amount. This sensor output g and constant voltage circuit 3
The setting output r of 6 is compared by a comparator 41, and r
<When g, the output of the comparator 41 is "H" level,
When the disconnector current is less than the disconnector breaking capacity, this signal becomes “L” level.
7" level, but when it exceeds the cutting capacity of the disconnector, the current is oscillatory, so it repeats "L" level and "H" level in a square waveform. Therefore, the signal is input for a certain period of time. If the current is passed through the hold circuit 42 that outputs a held output, it will always be at "H" level when the current of the disconnector is above the new circuit's breaking capacity, and always "L" when it is below the new circuit's breaking capacity.
A signal j having a level of
It is input with.

This AND gate 44 blocks the disconnector opening operation command when the disconnector current exceeds the disconnector breaking capability,
It is not output as an open operation signal. When the disconnector current is below the disconnector breaking capacity, the disconnector opening operation command is outputted as an opening operation signal through the AND gate 44. Note that the hold time of the hold circuit 42 needs to be at least longer than the cycle of the discharge current.

Each of the above specific examples (Figures 4 and 5) was described with the aim of installing a highly sensitive sensor in a small current range, but instead of installing a sensor, it is possible to You should be able to receive information. The second case will be explained using FIGS. 6 and 7.

6 and 7 show third and fourth specific examples of automatic disconnector operation circuits, and in these figures, a single current transformer 52 installed at one end of the disconnector 351 to be opened is shown. Current information is distributed to an amplifier 55 as a voltage signal using an auxiliary current transformer 53 and a resistor 54.

This amplifier 55 is provided for the purpose of amplifying a small current range, since although the output range of the current transformer is wide, the sensitivity of the current transformer is limited. The requirements for the amplifier 455 are that it has a large gain and is resistant to noise (l), linearity is not important, and a narrow range is sufficient.For this reason, the amplifier 55 is generally of the saturation type. It becomes a amplifier. The output of the J unit 55 passes through a judgment circuit 56 to block or permit the disconnector open operation command (C in the case of Fig. 6 and i in the case of Fig. 7) issued by the system automatic operation device. For the determination circuit 56, a part of FIG. 4 is applied in FIG. 6, and a part of FIG. 5 is applied in FIG. 7, and the operations of these circuit sections 56 are the same as described above.

The above-described automatic disconnector operation circuit (Figures 4 to 7) can create conditions for opening the disconnector not only for transient currents but also for steady currents, so it can be used for multiple new circuits. The system automatic operation device can determine the system automatic operation procedure based on the information on whether or not the container can be opened.

As described above, according to the automatic disconnector operation device according to the present invention, when opening a disconnector inserted in a power system, the disconnector current of the disconnector to be opened is detected, and the disconnector current of the disconnector to be opened is detected. determines whether the disconnector current is greater than the breaking capacity of the new circuit switch, and when the judgment output indicates that the current of the disconnector is greater than the breaking capacity, the system automatic operating device once sends a command to open the disconnector; Since the opening operation command is not sent again when the disconnector is not opened, it is possible to prevent the disconnector opening operation signal from being repeatedly sent out even when there is a failure of the new circuit. Further, according to the present invention, it is possible to sufficiently cope with the transient phenomenon of the discharge current during the opening operation of a disconnector inserted in the power system without being affected by it.

[Brief explanation of drawings]

Fig. 1 is a power system diagram for explaining the present invention, Fig. 2 is an equivalent circuit diagram showing a cable charge discharge circuit when circuit breakers 1 and 2 and new circuit switch 7 are open in Fig. 1; 3 is a circuit diagram showing one embodiment of the present invention, and FIGS. 4 to 7 are circuit diagrams showing specific examples of the automatic disconnector operation circuit applied to FIG. Breaker, 4-11.3
1.51 is a disconnector, 12.13 is a power system or generator, 15.16 is an underground cable transmission line, 17 is a transformer,
32 is a sensor, 33 is a rectifier, 34.41 is a comparator, 35.44 is an AND gate, 36 is a constant voltage circuit, 4
2 is a hold circuit, 43 is an inversion circuit, 52 is a current transformer, 5
3 is an auxiliary current transformer, 54 is a resistor, 55 is an amplifier, 56 is a determination circuit, 61 is a disconnector automatic operation circuit, 62 is an R-S flip-flop, 63 is an OR gate, 64 is a timer circuit,
c, i, Q, m are disconnector open operation commands, d, k,
o is a disconnector opening operation signal, and P is a hold release signal.

Claims (5)

[Claims] (1) When opening a disconnector inserted in the power system, detect the current of the disconnector, determine whether the current of the disconnector is greater than the disconnection capacity, and send out the determination output. When the current of the disconnector is higher than the disconnection capacity, the output of the detection/judgment circuit once sends out an operation command to open the disconnector from the system automatic operation device, and the disconnector is opened. An automatic disconnector operating device characterized by comprising a circuit that prevents the operation command from being sent out after a certain period of time unless the condition is established. (2) The detection/judgment circuit includes a detection circuit that uses a sensor that is highly sensitive in a small current range to detect the current of the disconnector installed at one end of the disconnector, and an output of this detection circuit that detects the disconnector current. 2. The automatic disconnector operating device according to claim 1, further comprising a determination circuit that determines whether or not the disconnection current is equal to or higher than the disconnection capability, and sends out the determination output. (3) The detection/judgment circuit includes a current transformer installed at one end of the disconnector to detect the current of the disconnector, and a nonlinear amplifier that amplifies the output of this current transformer in a small current range. and a determination circuit that determines whether or not the current of the disconnector is equal to or higher than the disconnection capability based on the output of the detection circuit, and sends out the determination output. Automatic operating device. (4) The determination circuit includes a rectifier that rectifies the detection circuit output;
Claim 2 comprising a level detection circuit that compares the output of the rectifier with a set value, determines whether the magnitude of the disconnector current is greater than the disconnector's disconnecting capacity, and sends out the determination output. Or the disconnector automatic operating device according to paragraph 3. (5) The determination circuit includes a level detection circuit that compares the detection circuit output with a set value, and holds the output of this level detection circuit for a certain period of time to determine whether the peak value of the disconnector current is greater than or equal to the disconnector's breaking capacity. The automatic disconnector operating device according to claim 2 or 3, comprising a hold circuit that sends out an output corresponding to the above.