JPS5910129A - Shortcircuit current suppressing device - 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 a short circuit current suppressing device for a power system.

Generally, when a ground fault or line-to-line circuit fault occurs in a power system, a large current flows and has a negative impact W on devices such as rectifiers connected to the power system. To prevent this, conventionally, for example, the first
A short-circuit suppression method was used as shown in the figure. In FIG. 1, the input side of the transformer 10 is connected to an AC power source (not shown), and the output side is connected to a power transmission line 3 via a current limiting reactor 2. F represents a ground fault accident. A thyristor switch 4 in which thyristors 4a and 4b are connected in antiparallel is connected to both ends of the current limiting reactor 20. In the circuit configured as described above, during normal operation, the thyristor switch 4 is turned on by a control circuit (not shown) to allow a current of five currents to flow through the thyristor switch 4, thereby supplying power from the f-voltage regulator 1 to the power transmission line 3. Here, if an accident such as a ground fault or a short circuit between lines occurs at point F in the diagram of the power transmission line 3, turn off the thyristor switch 4 to suppress the short circuit current through the current limiting reactor 2. However, in the short-circuit current suppression method as described above, it is necessary to keep the current flowing through the thyristor switch 4 at all times, which increases the current capacity of the thyristor. For this reason, the thyristor switch 4 has a larger capacity and a larger shape5, and since the thyristors 4a and 4b are always in a soldered state, the power loss due to their on-current increases, and the power loss of the grid increases accordingly. The thyristor switch 4 has disadvantages such as storage 1, and the method for extinguishing the thyristor switch 4 in the event of a short circuit accident is the thyristor 4a.

After cutting off the supply of gate current to thyristors 4b, the thyristors 4a and 4b are turned off for one cycle of alternating current. Therefore, in order to extinguish the thyristor switch 4, an energization period of a maximum of l cycles is required from the occurrence of the short circuit accident. This may cause a delay in suppressing the short-circuit current. Therefore, in order to quickly extinguish the thyristor switch 4 within a short period of time after the occurrence of a short-circuit accident, it is necessary to add a forced commutation circuit or the like. This has the disadvantage that the circuit configuration of the power system becomes complicated.

The present invention has been made in view of the above points, and includes a plurality of impedance elements inserted in an electric circuit that supplies alternating current power to loads of a power system and set so that impedance is approximately constant, and a plurality of impedance elements that 'ii connected in parallel to any one element and passing through the element
It is an object of the present invention to provide a short-circuit nine-flow suppression device equipped with a bypass switching element that bypasses the flow only in the event of a short-circuit accident.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, the same parts as in FIG. 1 are denoted by the same reference numerals, and the explanation thereof will be omitted. A plurality of impedance elements, such as a current limiting reactor 12 and a capacitor 3, are inserted in series in the electrical path connecting the transformer 1 and power transmission #i13. The impedance of current limiting reactor 2 and capacitor 3 is set to be Zo -10 OK. A bypass switching element such as a thyristor 14 is connected to both ends of the capacitor ω0 13. ,． 14t) connected in antiparallel is connected.

Next, the operation of the apparatus configured as described above will be explained. When the seats are occupied, the thyristor switch 14 is turned off by a control circuit (not shown) 1, and then an alternating current flows from the alternating current transformer l through the current limiting reactor 12 and the capacitor 3 to the power transmission line 3. At this time, since the sum of the impedances of the current limiting reactor 12 and the capacitor 13 is almost zero as described above, the output power of the AC transformer 1 is almost not lost and is supplied to the line 3. If an accident such as a ground fault or short circuit occurs at the illustrated point F of the transmission tR3, the thyristor switch 14 is switched to the unillustrated control circuit W!rvc.
So turn it on. Then, the output current of the AC transformer l is bypassed to the thyristor switch 14 side without passing through the capacitor 13. As a result, the short circuit current flows through the current limiting reactor 12 and the thyristor switch 14, and is therefore suppressed by the impedance of the current limiting reactor 12.

In the above embodiment, the thyristor switch 14 is connected to both ends of the capacitor 130, but even if the thyristor switch 14 is connected to both ends of the current limiting reactor 12, the short circuit can be suppressed in the same manner as described above.

As described above, according to the present invention, an impedance element whose argument is set so that the impedance is almost zero is inserted in the electric circuit that supplies AC power to the load of the power system, and any one of these one number of impedance elements is inserted. Bypass switching elements that are in the off state during normal operation are connected in parallel to one element, and in the event of a short circuit accident, the switching element is activated to bypass the short circuit current and suppress the short circuit current. During steady state, there is no power loss due to switching elements, and power loss in the grid is extremely small.
Further, since the switching element r allows current to flow only in the event of a short circuit accident, the current capacity of the switching element is reduced, and effects such as reduction in capacity and size can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a conventional short-circuit current suppression method for a power system, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Transformer, 3... Power transmission line, 12... Current limiting reactor, 13... Capacitor, 14... Thyristor switch, 14a, 14b... Thyristor.

Claims (1)

[Claims] It is inserted into the electrical circuit that supplies AC power to the load of the power system,
Multiple impedance elements set so that the impedance is approximately zero, and these? A short-circuit current suppressing device comprising: a bypass switching element which is connected in parallel to one of several impedance elements and is configured to bypass the current passing through the element only in the event of an electrical fault.