JPS6224889B2 - - Google Patents

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 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 transmission line will If the transient current is discharged through the transformer, load, etc., the disconnector opening operation shall 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, the cable's stray capacitance 21 and cable inductance 22 increase as shown in Figure 2.
Due to the resonance phenomenon of the resistor 23, the zero-sequence inductance 24 of the transformer, and the resistor 25, a damping transient current _i1 flows through the disconnector 6. This transient current _i1 may greatly exceed the disconnection capacity of the disconnector,
After the disconnector trips, the disconnector cannot be opened immediately; it can only be opened after this transient current becomes sufficiently small. This current usually disappears in a few seconds to tens of seconds, and conventional manual or manual startup (even if it is electric, it is started manually) requires human judgment and telephone contact with other substations and power supply stations. Therefore, it was carried out very 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.

The purpose of the present invention is to measure the disconnector current so as not to damage the contact part of the disconnector due to transient current when opening the disconnector, and if this exceeds the disconnector's breaking capacity,
This prevents the disconnector from being opened.

The present invention will be explained in detail below.

FIG. 3 shows a first embodiment of the automatic disconnector operating device according to the present invention. In the figure, 31 is the disconnector to be opened, which corresponds to the disconnector 6 in the above description. 32 is a highly sensitive sensor in a small current range installed at one end of the disconnector 31; 33;
is a rectifier which inputs the output obtained from the sensor 32 and sends out a DC voltage a proportional to the effective value of the current, and 34 determines whether the magnitude of the current of the disconnector is less than the disconnector's breaking capacity. It is a comparator that Therefore, this comparator 34 compares the DC voltage a with the set value output e of the constant voltage circuit 36,
If a>e (the magnitude of the disconnector current is greater than or equal to the disconnector's breaking capacity), the level is "L";e>a (the magnitude of the disconnector current is less than or equal to the disconnector's breaking capacity) If so, the "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. Note that current detection related to disconnectors 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. 4.

FIG. 4 shows a second embodiment of the automatic disconnector operating device according to the present invention, and the same reference numerals are used for the same parts or parts having the same functions as in FIG. 3. 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 36
The set outputs f of are compared by a comparator 41, and when f<g, the output h of the comparator 41 becomes an "H" level, and when f>g, an output h of the comparator 41 becomes an "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,
Repeat “H” level. Therefore, if the signal h is passed through the hold circuit 42 which outputs an output by holding the input for a certain period of time, when the current of the disconnector is above the disconnector's breaking capacity, it is always at "H" level, and is below the disconnector's breaking capacity. At this time, 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 the inverting circuit 43 and is input to the AND gate 44 together with the disconnector open operation command i from the system automatic operating device. By this AND gate 44, when the current of the disconnector exceeds the disconnector's breaking capacity, the disconnector opening operation command is blocked and the opening operation signal k is not output. When the current of the disconnector is below the disconnector's breaking capacity, the command to open the disconnector is AND gate 4.
4 and is output as the opening operation signal k. 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 embodiments (Figures 3 and 4) has been described on the premise that a sensor with high sensitivity in a small current range is installed. You can also get current information from the current device. This case will be explained using FIGS. 5 and 6.

5 and 6 show third and fourth embodiments of the automatic disconnector operating device according to the present invention, respectively,
In these figures, the disconnector 5 to be opened is
Current information from a current transformer 52 installed at one end of the amplifier 1 is distributed to an amplifier 55 as a voltage signal using an auxiliary current transformer 53 and a resistor 54. This amplifier 55
Although the current transformer has a wide output range, the sensitivity of this current transformer is poor, so it is provided for the purpose of amplifying the small current range. 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 saturated type amplifier. It becomes a purse. The output of the amplifier 55 is passed through a determination circuit 56 to block or permit a disconnector open operation command (c in the case of FIG. 5, i in the case of FIG. 6) issued by the system automatic operating device. For the determination circuit 56, a part of the first embodiment of the present invention in FIG. 3 is applied in FIG. 5, and a part of the second embodiment in FIG. 4 is applied in FIG.
The operations of these circuit sections 56 are the same as described above.

As described above, when the automatic disconnector operating device according to the present invention is used, when opening a disconnector inserted in a power system, the disconnector current of the disconnector to be opened is detected, and the disconnector is opened. Determines whether or not the current is greater than the disconnection capacity of the disconnector, and based on the judgment output, when the current of the disconnector exceeds the disconnection capacity, prevents the system automatic operating device from issuing an operation command to open the disconnector. This makes it possible to prevent the disconnector from opening. Therefore, when automatic system operation is performed by an automatic system operation device such as an automatic restoration device, a series of system operations are performed extremely quickly.If the present invention is applied to such a case, The opening operation of the device can be fully handled without being affected by transient phenomena of discharge current.

[Brief explanation of the drawing]

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 FIGS. 3 to 6 are each a disconnector according to the present invention. It is a circuit diagram showing each embodiment of the automatic operation device, and in the figure, 1 to 3 are the bridges and disconnectors, 4 to 11, and 3.
1 and 51 are disconnectors, 12 and 13 are power supply systems or generators, 15 and 16 are underground cable transmission lines, 1
7 is a transformer, 32 is a sensor, 33 is a rectifier, 3
4 and 41 are comparators, 35 and 44 are AND gates, 36 is a constant voltage circuit, 42 is a hold circuit,
43 is an inverting 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, i and l are disconnector open operation commands, and d and k are disconnector open operation commands. It is an operation 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 that sends out a judgment output, and when the current of the disconnector exceeds the disconnection capacity, the output of the detection/judgment circuit prevents a command from the system automatic operating device to open the disconnector. An automatic disconnector operating device characterized by: 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.