JP2569560B2 - Semiconductor breaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses a semiconductor element that can be turned on / off externally, that is, a semiconductor switching element, to quickly remove a short circuit accident occurring in an AC circuit. The present invention relates to a semiconductor circuit breaker for an AC circuit.

[Prior Art] Generally, when a short circuit accident occurs in a circuit such as an electric power system, a method of interrupting a circuit after several cycles by a circuit breaker is generally used. However, In such a powered electrode to block the opening and release the current mechanical circuit breaker, that the electrode was short-circuited at time T ₁ as shown in Figure 4 is blocked in a time T ₂ of the open release current zero However, transmission lines, cables, and electrical equipment are required to have short-circuit strength that can withstand the short-circuit current of a large current caused by several cycles. It is a factor to expand.

On the other hand, with the recent advancement of power electronics, breakers or current limiters using semiconductors have been developed. It is known that the use of a semiconductor allows the fault current to be limited at a speed incomparable with the prior art, so that the above problem can be greatly improved. In this semiconductor circuit breaker, a large number of self-extinguishing semiconductor elements, for example, GTO thyristor elements, which can be turned on / off externally, are connected in series and parallel to enable high voltage and high current interruption.
As shown in FIG. 5, when a short-circuit fault occurs at time T _1, since the turn-off time of the GTO thyristor is about 30 .mu.s, by commutation circuit current in current limiting circuit after the turn-off time T ₃ , a much shorter time T ₄ from mechanical circuit breaker described above, can be blocked limiting short-circuit current is small generator initial state.

[Problems to be solved by the invention]

The problems of the semiconductor circuit breaker configured in this way are technical difficulties to solve, such as control simultaneity when controlling a large number of semiconductor devices simultaneously, uniformity of voltage sharing and current sharing of each device. There is a problem and the cost as a circuit breaker becomes enormous.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor circuit breaker which has few technical problems as in the conventional semiconductor circuit breaker and does not require much cost.

[Means for solving the problem]

To achieve the above object, according to the present invention, a series transformer inserted in series into a secondary circuit of a main transformer and having a primary winding excited by the main transformer, A semiconductor breaker is formed by using a semiconductor switch that is connected in anti-parallel with a controllable self-extinguishing type semiconductor element and is connected to a secondary winding of the series transformer. When the current of the secondary circuit is cut off, the semiconductor switch is first turned off so that the primary winding of the series transformer acts as an obstruction loop to cut off the current.

[Action]

By configuring the semiconductor circuit breaker as described above, the secondary winding voltage of the series transformer can be set arbitrarily. Therefore, the number of series-connected semiconductor elements constituting the semiconductor switch connected to the secondary winding And the number of parallels can be changed arbitrarily,
For example, by reducing the number of series stages to simultaneously solve the problems of control concurrency and element voltage sharing, it is possible to easily solve only the current sharing problem, and details will be described in the following embodiments. As described above, the configuration of the secondary winding circuit of the series transformer requires only a small capacity of the series transformer, and has an advantage that the cost of the semiconductor circuit breaker is greatly reduced. Further, as described above, since the current of the semiconductor switch can be cut off within one cycle, the capacity of the semiconductor breaker can be reduced as compared with the case where a normal mechanical breaker is used.

In addition, the interruption of the current by the semiconductor circuit breaker having the above configuration is essentially a current-limiting interruption in which the primary winding of the series transformer is an obstruction loop, and is connected to the secondary circuit of the main transformer. Since the exciting current for the primary winding of the series transformer remains, a switching device such as a disconnector for completely shutting off the exciting current may be added to the secondary circuit of the main transformer.

(Example of the invention)

Next, examples of the present invention will be described. FIG. 1 shows a first embodiment of the present invention by a single-phase circuit.
In general, a series transformer 2 and a semiconductor switch 3 for connecting a semiconductor switch are added to a circuit formed by the main transformer 1 and the load 4. This semiconductor switch is formed by connecting a plurality of GTO thyristor elements known as self-turn-off devices in series and parallel, for example, in antiparallel. Since the 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 the absence of the additional circuit. However, when an accident occurs in which the load is short-circuited as shown in FIG. Let it. When the semiconductor switch 3 is turned off, the impedance seen from the primary side of the series transformer 2 instantaneously increases, so that the secondary voltage of the main transformer 1 is applied to the primary winding of the series transformer 2,
The load side voltage becomes zero, and the circuit current is rapidly limited.

In the method shown in FIG. 1, the transformers 1 and 2 need to have the same capacity. FIG. 2 shows an embodiment in which this is improved.

The main transformer 11 to the tertiary winding 113 is provided, even during normal so as to issue a voltage of E ₂₁ on the primary side of the series transformer 12.
At this time, if E ₁₂ = E ₂₁ (E ₁₂ is the secondary voltage of the main transformer 11), the capacity of the series transformer 12 can be half that of the main transformer.

FIG. 3 shows another embodiment, which is an application example applied to a large-capacity circuit. That is, the series transformer 22 is divided into a number of partial series transformers 23... 2N, the primary windings of each partial series transformer are connected in series, and the same number of tertiary and subsequent windings as the partial series transformers are connected. Lines 213 to 21N are provided in the main transformer 21, and the secondary windings of the respective partial series transformers are excited from the tertiary and subsequent windings through the semiconductor switches 233 to 23N, respectively. In addition, it can be applied to a large capacity circuit.

〔The invention's effect〕

When a high-speed current cutoff of a circuit is performed by using a semiconductor switch, if the semiconductor switch is directly inserted into the circuit as in the related art, the semiconductor switch is naturally required to have a performance capable of withstanding the voltage and current conditions of the circuit. However, according to the present invention, since the current, voltage, and capacity can be set freely without being restricted by the applied circuit, the technical problems in the conventional semiconductor circuit breaker that connects a large number of semiconductor elements in series and parallel are reduced. And providing a tertiary or tertiary winding on the main transformer to excite the secondary winding of the series or partial series transformer, Since the capacity or the total capacity of the partial series transformer can be reduced, the cost of the circuit breaker does not need to be so large. In addition, the current can be cut off in a much shorter time than the cut-off time of the mechanical circuit breaker by turning off the self-arc-extinguishing type semiconductor element, so the load connected to the main transformer is limited in the initial state of short-circuit current and cut off. Has the great advantage of being able to Therefore, the applicable range of the semiconductor circuit breaker based on the configuration principle of the present invention is infinitely widened.
If the excellent current limiting / cutoff characteristics become widely applied to conventional AC circuits, the equipment connected to the lower system will
The concept of short-circuit tolerance can be renewed. The cost merit of this is considered to be immeasurable.

[Brief description of the drawings]

FIG. 1, FIG. 2 and FIG. 3 respectively show the first and second embodiments of the present invention.
FIG. 4 is a circuit configuration diagram of a semiconductor circuit breaker according to the second and third embodiments, and FIGS. 4 and 5 are current interruption characteristic diagrams of a semiconductor circuit breaker including a mechanical circuit breaker and a self-extinguishing type semiconductor element, respectively. It is. 1,11,21 …… Main transformer, 2,12,22 …… Series transformer, 23-2N
…… Partial series transformer, 113 …… Tertiary winding, 213-21N ……
Third and subsequent windings, 3,13,233 to 23N ... Semiconductor switch.

Claims (3)

(57) [Claims] 1. A main transformer connected in series to a secondary circuit of a main transformer.
A series transformer in which a secondary winding is excited by the main transformer;
A semiconductor switch in which a self-extinguishing type semiconductor element that can be turned on / off from the outside is connected in anti-parallel and connected to a secondary winding of the series transformer, and a secondary circuit of the main transformer is provided. The semiconductor circuit breaker characterized in that the semiconductor switch is first turned off at the time of interrupting the current so that the primary winding of the series transformer acts as a blockage loop to cut off the current. 2. A semiconductor circuit breaker according to claim 1, wherein the main transformer has a tertiary winding, and the secondary winding of the series transformer to which the semiconductor switch is connected is connected to this switch. Characterized by being excited by the tertiary winding via a semiconductor circuit breaker. 3. The semiconductor circuit breaker according to claim 1, wherein the series transformers inserted in series in the secondary circuit of the main transformer have respective primary windings connected in series. The main transformer is composed of a partial series transformer.
In addition to the secondary winding and the secondary winding, the same number of tertiary and subsequent windings as the partial series transformer are provided and connected to the secondary windings of the partial series transformer via semiconductor switches, respectively. A semiconductor circuit breaker characterized by the above-mentioned.