DE202012100024U1 - HVDC HYBRID circuit breaker with protective circuit - Google Patents

Abstract

A DC circuit breaker (100) comprising: a main circuit breaker (110) and an interrupter (120) and an auxiliary circuit breaker (170) connected in series, the series circuit comprising the interrupter and the auxiliary circuit breaker with the main circuit breaker is connected in parallel, the auxiliary power switch (170) comprising: a first circuit structure (251) comprising: a power semiconductor switching element (210), a first diode (225) having a first polarity and with the power semiconductor switching element (210) is connected in series, and a protection circuit which is connected in parallel with the power semiconductor switching element (210), the protection circuit comprising: a capacitor (221), a first resistor (222) which is connected to the capacitor (221 ) is connected in parallel, a second diode (223) which has the first polarity and a second resistor (224) which is connected to the second Diode (223) is connected in parallel, the parallel connection of the second diode (223) and the second resistor (224) with the ...

Description

FIELD OF THE INVENTION

The invention relates generally to high voltage direct current (HVDC) hybrid power switches and more particularly to protective circuits in such power switches.

BACKGROUND OF THE INVENTION

HVDC hybrid circuit breakers, such as those in WO 2011/057675 are usually based on a combination of a solid-state main power switch, which is connected in parallel with a series circuit of a solid state auxiliary power switch and a mechanical breaker. The operating principle of a hybrid circuit breaker is that the main circuit breaker, the auxiliary circuit breaker and the breaker are closed during normal operation. When a trip signal is received, the hybrid power switch attempts to interrupt the current flowing through it by first opening the auxiliary power switch, thereby commutating the current flowing through the auxiliary power switch and the breaker to the main power switch. Subsequently, the breaker is opened to disconnect the auxiliary power switch, and finally the main power switch is opened, resulting in a commutation of the current flowing from the main power switch to a surge arrester connected in parallel with the main power switch.

Frequently, hybrid power switches are provided with protection circuits to suppress voltage transition conditions that arise in response to the sudden interruption of the current when the breaker is opened. A protective circuit usually comprises a capacitor which is connected in parallel with the auxiliary power switch.

When the interruption operation of the hybrid power switch is initiated by opening the auxiliary power switch, the snubber capacitor is charged, but as soon as the current commutes from the auxiliary power switch to the main power switch, the capacitor is discharged through the breaker and the main power switch. This discharge process, and the resulting non-zero current through the breaker, interferes with the interruption operation of the breaker.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a more efficient alternative to the techniques described above and the prior art.

More specifically, it is an object of the present invention to provide an improved hybrid HVDC circuit breaker.

These and other objects of the present invention are achieved by means of a direct current (DC) circuit breaker having the features defined in independent claim 1. Embodiments of the invention are characterized by the independent claims.

In accordance with one aspect of the invention, a DC power switch is provided. The circuit breaker comprises a main circuit breaker, a breaker and an auxiliary circuit breaker. The breaker and the auxiliary circuit breaker are connected in series. The series connection of breaker and auxiliary circuit breaker is connected in parallel with the main circuit breaker. The auxiliary power switch includes a first circuit structure and a second circuit configuration. The first circuit configuration includes a power semiconductor switching element, a first diode, and a protection circuit. The first diode has a first polarity and is connected in series with the power semiconductor switching element. The protective circuit comprises a capacitor, a first resistor, a second diode and a second resistor. The first resistor is connected in parallel with the capacitor. The second diode has the first polarity. The second resistor is connected in parallel with the second diode. The parallel connection of the second diode and the second resistor is connected in series with the parallel connection of the capacitor and the first resistor. The second circuit construction is identical to the first circuit construction. The first and second circuit structures are connected in anti-parallel with each other.

The present invention takes advantage of the knowledge that uncontrolled discharge of the snubber capacitor during the cut-off operation of a hybrid HVDC circuit breaker can be prevented by providing the auxiliary power switch with a diode connected in series with the power semiconductor switch element. The diode prevents uncontrolled discharge of the damping capacitor through the main power switch. Further, by providing two identical branches which are anti-parallel to each other, bidirectional operation of the circuit breaker is possible.

An embodiment of the invention is advantageous in that the problems associated with the prior art hybrid circuit breakers, that is, problems due to a discharge current, which flows from the capacitor through the breaker and the main power switch, are reduced. More specifically, the non-zero current flowing through the breaker of a prior art hybrid power switch obstructs the interrupting action of the breaker. On the other hand, in an embodiment of the present invention, uncontrolled discharging of the capacitor is prevented, whereby the breaker can interrupt the current.

According to one embodiment of the invention, the power semiconductor switching element comprises an insulated gate bipolar transistor (IGBT) and a third diode. The IGBT has a second polarity. The third diode has the first polarity. The third diode is connected in parallel with the IGBT. The first polarity is opposite to the second polarity.

According to one embodiment of the invention, the power semiconductor switching element comprises a bi-mode insulated gate transistor (BiGT) and a third diode. The BiGT has a second polarity. The third diode has the first polarity. The third diode is connected in parallel with the BiGT. The first polarity is opposite to the second polarity.

According to one embodiment of the invention, the main power switch comprises a plurality of power semiconductor switching elements. The switching elements are connected in series.

According to one embodiment of the invention, the breaker comprises a mechanical switch.

According to one embodiment of the invention, the auxiliary power switch comprises a power semiconductor switching element. Furthermore, the auxiliary power switch may include a plurality of power semiconductor switching elements connected in series.

While advantages of the present invention have been described in some instances with respect to embodiments of the hybrid power switch of the first aspect of the invention, considerations apply to embodiments of the method of the second aspect of the invention.

Other objects, features, details, embodiments, and advantages of the present invention will become apparent from the following detailed disclosure, the drawings, and the appended claims. Those skilled in the art will recognize that various features of the present invention may be combined to produce embodiments other than those described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will be better understood by the following illustrative and non-limitative detailed description of embodiments of the present invention, taken in conjunction with the accompanying drawings, in which:

1 FIG. 10 is a schematic illustration of a prior art HVDC hybrid circuit breaker. FIG.

2 FIG. 12 is a schematic illustration of a hybrid HVDC circuit breaker according to one embodiment of the invention. FIG.

All figures are diagrammatic, not necessarily to scale and generally show only parts necessary to understand the invention, other parts being omitted or merely hinted at.

DETAILED DESCRIPTION

Regarding 1 An HVDC hybrid circuit breaker of the prior art will be described.

The hybrid circuit breaker 100 includes a main circuit breaker 110 , a fast breaker, ie a high-speed switch, 120 , an auxiliary circuit breaker 130 , a surge arrester 140 and a snubber capacitor 150 , The breaker 120 and the auxiliary circuit breaker 130 are connected in series, and the series circuit of breakers 120 and auxiliary circuit breakers 130 is with the main circuit breaker 110 connected in parallel. The surge arrester 140 is with the main circuit breaker 110 and the series circuit of breakers 120 and auxiliary circuit breakers 130 connected in parallel. The damping capacitor 150 is with the auxiliary circuit breaker 130 connected in parallel.

The hybrid circuit breaker 100 can connect to an external circuit, such as an HVDC transmission line 101 and 102 be connected. For example, the hybrid circuit breaker 100 used to connect an HVDC transmission line to a switchgear busbar to disconnect the transmission line from the busbar in the event of a technical malfunction or maintenance.

The following is the operating principle of the hybrid circuit breaker 100 described. During normal operation, the main circuit breaker 110 , the breaker 120 and the auxiliary circuit breaker 130 closed. If the hybrid circuit breaker 100 receives a trip signal, the circuit breaker tries 100 , the current flowing through it, ie from the terminal 101 to 102 or vice versa, by first turning off the auxiliary circuit breaker 130 opens, reducing the current passing through the auxiliary circuit breaker 130 and the breaker 120 to the main circuit breaker 110 flows, is commuted. Subsequently, the breaker 120 opened to the auxiliary circuit breaker 130 and finally becomes the main circuit breaker 110 open, resulting in a commutation of the current from the main circuit breaker 110 to the surge arrester 140 leads.

The hybrid circuit breaker 100 is with a snubber capacitor 150 equipped to suppress voltage transients that arise in response to the sudden interruption of the current when the interrupter 120 is opened.

A problem encountered in prior art hybrid circuit breakers, such as that described with reference to FIGS 1 described hybrid circuit breaker 100 , that is, is that the charged snubber capacitor 150 through the breaker 120 and the main circuit breaker 110 is discharged when the auxiliary circuit breaker 130 is opened as indicated by the arrow 160 in 1 is illustrated. As a result of the current not equal to zero, that through the breaker 120 flows, the interruption effect of the breaker 120 with special needs.

Hereinafter, an embodiment of the invention with reference to 2 described. For ease of illustration, only the auxiliary circuit breaker is in 2 illustrated, ie the in 2 illustrated circuitry corresponds to the circuit structure 170 from 1 ,

The auxiliary circuit breaker 200 includes two identical branches 251 and 252 , which are connected to each other anti-parallel. The first branch 251 includes a diode 225 which is anti-parallel to the transistor of a power semiconductor switching element 210 is switched, as in 2 is illustrated. The transistor included in the power semiconductor switching element 210 is included, z. As an IGBT or a BiGT. Furthermore, the first branch includes 251 a protective circuit, which is a capacitor 221 , a resistance 222 leading to the capacitor 221 is connected in parallel, a diode 223 and a resistance 224 that's to the diode 223 is connected in parallel includes.

The purpose of the power semiconductor switching element 210 series connected diode 225 is it, unloading the snubber capacitor 221 by the breaker and the main circuit breaker of the hybrid circuit breaker. The anti-parallel connection of the first branch 251 and the second branch 252 allows bidirectional operation of the circuit breaker.

Those skilled in the art will recognize that the present invention is by no means limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

In summary, it can be said that a hybrid HVDC circuit breaker is provided. The circuit breaker includes a solid main circuit breaker, a mechanical quick breaker and an auxiliary circuit breaker. The breaker and the auxiliary circuit breaker are connected in series. The auxiliary power switch comprises a first branch comprising a power semiconductor switching element, a snubber capacitor and a diode. The diode is connected in series with the power semiconductor switching element, so that uncontrolled discharge of the damping capacitor is prevented by the main power switch. Further, the auxiliary power switch comprises a second branch identical to the first branch and connected in anti-parallel to the first branch. The antiparallel connection of the first and second branches allows bidirectional operation of the circuit breaker.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2011/057675 [0002]

Claims (7)

DC (power) circuit breaker ( 100 ), comprising: a main circuit breaker ( 110 ) and a breaker ( 120 ) and an auxiliary circuit breaker ( 170 ), which are connected in series, wherein the series circuit of the breaker and the auxiliary power switch with the main power switch is connected in parallel, wherein the auxiliary power switch ( 170 ) Comprises: a first circuit structure ( 251 ), comprising: a power semiconductor switching element ( 210 ), a first diode ( 225 ) having a first polarity and connected to the power semiconductor switching element ( 210 ) is connected in series, and a protective circuit connected to the power semiconductor switching element ( 210 ), wherein the protective circuit comprises: a capacitor ( 221 ), a first resistor ( 222 ) connected to the capacitor ( 221 ) is connected in parallel, a second diode ( 223 ), which has the first polarity, and a second resistor ( 224 ) connected to the second diode ( 223 ) is connected in parallel, wherein the parallel connection of the second diode ( 223 ) and the second resistance ( 224 ) with the parallel connection of the capacitor ( 221 ) and the first resistance ( 222 ) is connected in series, and a second circuit structure ( 251 ) which is identical to the first circuit construction, wherein the first circuit construction ( 251 ) and the second circuit structure ( 251 ) are connected to each other anti-parallel. The DC power switch according to claim 1, wherein the power semiconductor switching element comprises an insulated gate bipolar transistor, IGBT, having a second polarity, and a third diode, which preferably has the first polarity and is preferably connected in parallel with the IGBT , wherein the first polarity is preferably opposite to the second polarity. The DC power switch according to claim 1, wherein the power semiconductor switching element comprises a bi-mode insulated gate transistor, BiGT, having a second polarity, and a third diode, which preferably has the first polarity, and preferably with the BiGT is connected in parallel, wherein the first polarity is preferably opposite to the second polarity. A DC circuit breaker according to any one of the preceding claims, wherein the main power switch comprises a plurality of power semiconductor switching elements connected in series. A DC circuit breaker according to any one of the preceding claims, wherein the breaker comprises a mechanical switch. A DC circuit breaker according to any one of the preceding claims, wherein the auxiliary power switch comprises a power semiconductor switching element. A DC circuit breaker according to any one of the preceding claims, wherein the auxiliary power switch comprises a plurality of power semiconductor switching elements connected in series.

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