JPS649688B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic disconnector operating device for high-speed operation of a disconnector.

When opening a disconnector, it is necessary to pay attention to the disconnection capacity 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, that no power source or load is connected to both ends of the disconnector. In a no-voltage state, that is, when the power supply is not connected, the disconnector can generally be opened, but immediately after it is disconnected from the power supply, the charge accumulated in the stray capacitance of the power transmission line will cause the disconnector to open. If the transient current is discharged by the transformer, load, etc., the disconnector opening operation must be prohibited until this transient current has sufficiently attenuated.

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

In Figure 1, 1 to 3 bridges and disconnectors, 4 to 11
12 and 13 are power supply systems or generators, 14 is a load, 15 and 16 are underground cable transmission lines, and 17 is a transformer.

Now, the disconnector 7 is opened and the power supply 12 is connected to the load 1.
Cable 15 while power is being supplied to 4.
Assume that an accident occurs and the circuit breakers 1 and 2 are tripped by the protective relay. 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 disconnector are met. However, for a while after the circuit breakers 1 and 2 trip, as shown in FIG. A damping transient current i ₁ flows through the disconnector 6 due to the resonance phenomenon. This discharge current _i1 may greatly exceed the disconnecting capacity of the disconnector, and after the disconnector trips, the disconnector cannot be opened immediately; it can only be opened after this transient current becomes sufficiently small. becomes. This current usually disappears in a few seconds to several tens of seconds, and in the case of conventional manual or manual activation (even if it is electric, it is started manually). Because it involved human judgment and telephone contact with other substations and power supply stations, it was carried out extremely slowly, 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 will not open after a certain period of time after issuing the disconnector open operation signal to the system automatic operation device. If not, the disconnector opening operation signal will be issued again and this will be repeated until the disconnector is in the open state, which is not preferable.

The purpose of the present invention is to measure the disconnector current so as not to damage the contact part of the disconnector when operating the disconnector due to transient current, and if this is less than the disconnector's breaking capacity, it will once send a command to open the disconnector. However, it is designed to prevent the command from being issued again when the disconnector is not opened.

The present invention will be explained in detail below.

FIG. 3 shows an embodiment of the automatic disconnector operation device according to the present invention. In the figure, 61 is an automatic disconnector operation circuit, and the automatic disconnector operation circuit 61 is shown in FIGS. 4 to 7. Each circuit shown is used. Reference numeral 62 denotes an R-S flip-flop, which immediately outputs a disconnector open operation command m to the disconnector automatic operation circuit 61 when a disconnector open operation command l from the system automatic operation device is inputted to the set terminal S. This disconnector opening operation command m corresponds to c in FIGS. 4 and 6, which will be described later, and 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 l from a system automatic operating device and sends out an output n after a certain period of time T.

Next, to explain the operation, the disconnector open operation command l from the system automatic operating device is input to the R-S flip-flop 62 and at the same time the timer circuit 64
Start. The R-S flip-flop 62 immediately issues a command to the disconnector automatic operation circuit 61 to open the disconnector.
issue. The automatic disconnector operation circuit 61 outputs a disconnector open operation signal o when a predetermined condition is satisfied. This disconnector opening operation signal o corresponds to d in FIGS. 4 and 6, which will be described later, and corresponds to k in FIGS. 5 and 7.

This disconnector open operation signal o is output, the disconnector open operation command l is issued, and after a certain period of time T, the output n of the timer circuit 64 is output, or the system automatic operation device outputs the hold release signal P. If so, signal q is input to the reset terminal R of the RS 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 that the disconnector will be disconnected from now on. No device opening operation signal is sent. Therefore, it is possible to avoid repeatedly sending out the opening operation signal until the disconnector is in the open state.

Next, a specific example of the automatic disconnector operation circuit 61 will be described using FIGS. 4 to 7.

FIG. 4 shows a first specific example of the 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 with high sensitivity in a small current range installed at one end of the disconnector 31; 33 is a sensor 32;
34 is a comparator that determines whether the magnitude of the current of the disconnector is below the disconnection capacity of the disconnector. be. Therefore, the 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's breaking capacity), it becomes "L". If the level e>a (the magnitude of the current of the disconnector is less than the disconnector's breaking capacity), an "H" level signal b is output. The disconnector opening operation command c coming from the system automatic operating device is blocked by the AND gate 35 when a>e, and 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 disconnecting switches and disconnecting capabilities is related to a very small current range compared to normal power flow, and does not require a wide range like relays or current transformers for measurement, but instead can be used as a sensor. High sensitivity in the small current range is required. Also, the linearity of the sensor is not very important.

Next, in order to detect the magnitude of the disconnector current, the peak of the output of the sensor 32 may be detected, and this case will be explained using FIG. 5.

FIG. 5 shows a second specific example of the automatic disconnector operation circuit, and the same reference numerals are used for the same parts or parts having the same functions as in FIG. 4. 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 the setting output f of the constant voltage circuit 36 are compared by a comparator 41, and when f<g, the output h of the comparator 41 is at "H" level, and f>
When it is g, it becomes "L" level. This signal h is always at the "L" level when the disconnector current is below the disconnector's breaking capacity, but when it is above the disconnector's breaking capacity, the signal h is in the form of a square wave because the discharge current is oscillatory. “L” level and “H” level are repeated.
Therefore, if the signal h is passed through the hold circuit 42 that holds the input for a certain period of time and outputs an output, it will always be "H" when the disconnector current exceeds the disconnector's disconnection capacity.
When the level is below the disconnecting capacity of the disconnector, a signal j that is always at the "L" level is obtained as the output of the hold circuit 42. This signal j passes through an inverting circuit 43,
The command is input to the AND gate 44 along with the disconnector open operation command i from the system automatic operating device. By this AND gate 44, when the current of the disconnector is higher than the disconnector's breaking capacity, the command to open the disconnector is blocked,
The opening operation signal k is not output. When the disconnector current is below the disconnector's breaking capacity, the disconnector opening operation command is outputted as an opening operation signal k 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 on the premise that a sensor with high sensitivity in a small current range is installed, but instead of installing a sensor, current information can be obtained from an existing current transformer. You can also receive. This case will be explained using FIGS. 6 and 7.

FIG. 6 and FIG. 7 show third and fourth specific examples of the automatic disconnector operation circuit, and in these figures, the current from the current transformer 52 installed at one end of the disconnector 51 to be opened is shown. Current information auxiliary current transformer 53
and an amplifier 55 as a voltage signal using a resistor 54.
to be distributed. 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 poor.
The requirements for the amplifier 55 are that it has a large gain and is resistant to noise, linearity is not important, and a narrow range is sufficient.For this reason, the amplifier 55 is generally a saturation amplifier. Become a vessel. Amplifier 55
The output of is passed through 56 judgment circuits and outputs a disconnector open operation command (c, in the case of Fig. 6) issued by the system automatic operation device.
In the case of Figure 7, i) is blocked or allowed. For the determination circuit 56, a part of FIG. 4 is applied in FIG. 6, a part of FIG. 5 is applied in FIG.
The operations of these circuit sections 56 are the same as described above.

The above-mentioned automatic disconnector operation circuit (Figures 4 to 7)
(Figure) can create conditions for whether or not the relevant disconnector can be opened not only for transient currents but also for steady currents, so the system automatic operation device can automatically operate the system based on information on whether or not multiple disconnectors can be opened. The procedure can be determined.

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. It is determined whether or not the disconnector current is greater than or equal to the breaking capacity of the disconnector, and based on the judgment output, when the current of the disconnector is less than or equal to the line breaking capacity, the system automatic operating device issues a command to open the disconnector. Since the opening operation command is not sent out again when the disconnector is not opened, it is possible to prevent the disconnector open operation signal from being repeatedly sent out even when there is a failure of the disconnector. 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 the cable charge discharge circuit when the disconnectors 1, 2 and 7 are open in Fig. 1, and Fig. 3 is a circuit diagram showing an embodiment of the present invention. , FIG. 4 to FIG. 7 are circuit diagrams showing specific examples of the automatic disconnector operation circuit applied to FIG.
1 is a disconnector, 12 and 13 are power supply systems or generators, 15 and 16 are underground cable transmission lines, 17 is a transformer, 32 is a sensor, 33 is a rectifier, 34 and 41
is a comparator, 35 and 44 are AND gates, 3
6 is a constant voltage circuit, 42 is a hold circuit, 43 is an inversion circuit, 52 is a current transformer, 53 is an auxiliary current transformer, 54
is a resistor, 55 is an amplifier, 56 is a judgment 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, l, m are disconnector open operation commands, d, k, o
is a disconnector open operation signal, and P is a hold release signal.

Claims (1)

[Scope of Claims] 1. When opening a disconnector inserted in a power system, the current of the disconnector is detected, it is determined whether the current of the disconnector is greater than the disconnection capacity of the disconnector, and the A detection/judgment circuit is provided to send out a judgment output, and when the current of the disconnector is below the disconnection capacity, the output of the detection/judgment circuit once sends out a command to open the disconnector from the system automatic operating device; An automatic disconnector operating device comprising a circuit that prevents an operation command from being sent out after a certain period of time unless the disconnector is in an open state. 2 The detection/judgment circuit consists of 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 a detection circuit that uses a sensor that is highly sensitive in a small current range to detect the current of the disconnector using the output of this detection circuit. The automatic disconnector operating device according to claim 1, comprising a determination circuit that determines whether the disconnection or disconnection capacity is exceeded and sends out the determination output. 3. The detection/judgment circuit consists of 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. Automatic operation of a disconnector according to claim 1, comprising a detection circuit and a determination circuit that determines whether the current of the disconnector is equal to or higher than the disconnection capacity based on the output of the detection circuit and sends out the determination output. Device. 4 The determination circuit compares the rectifier that rectifies the detection circuit output and the rectifier output with a set value, determines whether the magnitude of the disconnector current is greater than the disconnector's disconnection capacity, and sends out the determination output. 3. An automatic disconnector operating device according to claim 2 or 3, comprising a level detection circuit. 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, and determines whether the peak value of the disconnector current is greater than or equal to the disconnector's breaking capacity. An automatic disconnector operating device according to claim 2 or 3, comprising a hold circuit that sends out a corresponding output.