JPS63296517A - Semiconductor interrupter - Google Patents

Abstract

PURPOSE:To reduce the cost of an interrupter by applying OFF-control to a semiconductor switch connected to the secondary winding of a series transformer at the current interruption of the circuit at the secondary winding of a transformer so as to act the primary winding of the series transformer as a choke coil thereby interrupting the current. CONSTITUTION:The semiconductor interrupter consists of the series transformer 2 whose primary winding is energized by a main transformer 1 while being inserted in series with the circuit of the secondary winding of the main transformer 1 and a semiconductor switch 3 connected in anti-parallel with the semiconductor element being able to be ON/OFF control externally and connected to the secondary winding of the series transformer 2, and the primary winding of the series transformer 2 is acted like a choke coil by applying OFF control to the semiconductor switch 3 at first at the current interruption of the secondary side circuit of the main transformer 1 to interrupt the current. Thus, the small capacity of series transformer is enough for the purpose and the cost of the semiconductor interrupter is remarkably reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention uses a semiconductor element that can be turned on and off from the outside, that is, a semiconductor switching element, to quickly eliminate short circuit accidents that occur in an AC circuit. Related to semiconductor circuit breakers for AC circuits.

[Conventional technology]

Normally, when a short circuit occurs in a circuit such as a single power system,
A common method is to use a circuit breaker to shut off the circuit after several cycles. However, when using this method, the power transmission lines, cables, and electrical equipment are required to have a short circuit strength that can withstand several cycles of short circuit current, and the construction cost and unit cost of the equipment are high. It is a factor that causes the expansion of

In contrast, with recent advances in power electronics, circuit breakers, current limiters, and the like using semiconductors have been developed. It is known that by using semiconductors, fault current can be limited at a speed incomparable to conventional methods, and the above problems can be greatly improved. This semiconductor circuit breaker is made by connecting a large number of semiconductor elements such as GTO thyristor elements in series and parallel, which can be turned on and off from the outside, to generate high voltage.

This makes it possible to cut off large currents.

[Problem that the invention seeks to solve]

What are the problems with the semiconductor circuit breaker constructed in this way?

Simultaneity of control when controlling a large number of semiconductor devices simultaneously,
Uniformity of voltage sharing and current sharing of each element, etc.

There are technical problems that are difficult to solve, and the cost of the circuit breaker is enormous.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor circuit breaker that has fewer technical problems than conventional semiconductor circuit breakers and does not require a significant increase in cost.

[Means for solving problems]

In order to achieve the above object, the present invention provides a series transformer that is inserted in series into a secondary circuit of a main transformer and whose primary winding is excited by the main transformer, and a series transformer that can be turned on and off from the outside. A semiconductor circuit breaker is configured using a semiconductor switch in which controllable semiconductor elements are connected in antiparallel and connected to the secondary winding of the series transformer, and At the time of current interruption, the semiconductor switch is first controlled to turn off, thereby causing the primary winding of the series transformer to act as a blocking wire to interrupt the current.

[Effect]

By configuring the semiconductor circuit breaker as described above, the secondary winding voltage of the series transformer can be set arbitrarily, so the number of series stages of semiconductor elements constituting the semiconductor switch connected to this secondary winding For example, by reducing the number of series stages, the problem of control simultaneity and voltage sharing of elements can be solved at once, and only the problem of current sharing can be easily solved. As will be explained in detail in the Examples section below, the configuration of the secondary winding circuit of the series transformer allows the series transformer to be of small capacity, which has the advantage of greatly reducing the cost of the semiconductor circuit breaker. arise.

Note that the current interruption by the semiconductor circuit breaker with the above configuration is essentially a current-limiting interruption in which the primary winding of the series transformer is used as a blocking wire, and the secondary circuit of the main transformer is Since the excitation current remains for the primary winding of the series transformer, a switching device such as a disconnector may be added to the secondary circuit of the main transformer to completely cut off this excitation current.

[Embodiments of the invention]

Next, examples of the present invention will be described. @1 Figure shows the first embodiment of the present invention as a single-phase circuit. 1 A series transformer 2 for connecting a semiconductor switch to a circuit normally formed by a main transformer 1 and a load 4. and a semiconductor switch 3 is added. This semiconductor switch is constructed by, for example, a plurality of GTO thyristor elements connected in series and parallel and connected in anti-parallel. Since this semiconductor switch is normally on, almost no voltage is generated on the primary side of the series transformer 2. Therefore, when the semiconductor switch is on, it is the same as if the additional circuit were not present. but,
As shown in FIG. 1, when an accident occurs in which the load is short-circuited, the current transformer 5 detects the current, the control section 6 detects an abnormality in the current, detects the accident, and turns off the semiconductor switch 3.

When the semiconductor switch 3 turns off, the impedance seen from the primary side of the series transformer 2 increases instantaneously, so that the secondary voltage of the main transformer 1 is applied to the primary winding of the series transformer 2, and the load The side voltage becomes zero and the circuit current is rapidly limited.

In the method shown in FIG. 1, transformers 1 and 2 must have the same capacity. An embodiment that improves this problem is shown in FIG.

A tertiary winding 113 is provided in the main transformer 11, and E2
A voltage of 1 is made to appear on the primary side of the series transformer 12. At this time, if E12 = E21 (E12 is the secondary voltage of the main transformer 1), the capacity of the series transformer 12 will be % of the capacity of the main transformer.

What is shown in FIG. 3 is yet another embodiment, which is an example of application to a large capacity circuit. That is, the series transformer n is divided into a large number of partial series transformers...2N, the primary windings of each partial series transformer are connected in series, and the tertiary windings of the same number of partial series transformers are connected in series. Subsequent windings 213~
21N in the main transformer 21, and 21N in each partial series transformer.
The next winding is excited from the tertiary and subsequent windings through the semiconductor switches 233 to 23N, and can be applied to a very large capacity circuit.

〔Effect of the invention〕

When a semiconductor switch is used to interrupt high-speed current in a circuit, if the semiconductor switch is directly inserted into the circuit as in the past, the semiconductor switch is naturally required to have performance that can withstand the voltage and current conditions of the circuit. However, according to the present invention, the current, voltage, and capacity can be freely set without being restricted by the applied circuit, which reduces the technical problems of conventional semiconductor circuit breakers that connect a large number of semiconductor elements in series and parallel. By providing a tertiary winding or a winding after the third in the main transformer to excite the secondary winding of the series transformer or partial series transformer, the series transformer can be Since the capacity or the total capacity of the partial series transformer can be reduced, the cost of the A-disconnector does not need to be so large. Therefore, the scope of application of the semiconductor circuit breaker based on the construction principle of the present invention is infinitely expanded. Its excellent current limiting-d
If cut-off characteristics are widely applied to conventional AC circuits, the concept of short-circuit tolerance can be completely changed for equipment connected to lower-level systems. The cost benefits of this are considered to be immeasurable.

[Brief explanation of drawings]

Figures 1, 2 and 3 each represent the first embodiment of the present invention.
．． FIG. 3 is a circuit configuration diagram of semiconductor circuit breakers according to second and third embodiments. 1.11.21...Main transformer, 2,12.22...
Series transformer. 23~2N...partial series transformer, 113...tertiary winding. 213~21N...Third and subsequent windings, 3, 13, 23
3～23N...l Wangduokuki device 5 1st Fig. 1/Maf Pressure device $2 Fig. 19

Claims (1)

[Claims] 1) A series transformer that is inserted in series into a secondary circuit of a main transformer and whose primary winding is excited by the main transformer, and a semiconductor element that can be turned on and off from the outside. and a semiconductor switch connected in antiparallel to the secondary winding of the series transformer, by first controlling the semiconductor switch to turn off when current in the secondary circuit of the main transformer is cut off. A semiconductor circuit breaker characterized in that the primary winding of the series transformer acts as a blocking wire to interrupt current. 2) In the semiconductor circuit breaker according to claim 1, the main transformer is provided with a tertiary winding, and the secondary winding of the series transformer to which the semiconductor switch is connected is connected to the semiconductor switch via the switch. A semiconductor circuit breaker characterized in that it is excited by a tertiary winding. 3) In the semiconductor circuit breaker according to claim 1, the series transformer inserted in series into the secondary circuit of the main transformer is a partial series transformer in which the respective primary windings are connected in series with each other. The main transformer consists of a primary winding and a secondary winding, as well as three windings, the same number as the partial series transformer.
A semiconductor circuit breaker, characterized in that the following windings are connected to the secondary windings of the partial series transformer via semiconductor switches.