CN106209039A - A kind of novel mixed type dc circuit breaker and power cell - Google Patents

Abstract

The invention relates to a novel hybrid DC circuit breaker and power unit. The DC circuit breaker includes a commutation branch connected in parallel, a breaking branch and an energy absorbing branch. The breaking branch includes several series connected breaking branches. unit, wherein the breaking unit adopts a specific power unit structure, the specific power unit structure includes at least one forward channel branch and at least one reverse channel branch connected in parallel, the forward channel branch and the reverse channel Each branch includes a fully-controlled power device and a diode connected in series in the same direction, and the conduction directions of the forward channel branch and the reverse channel branch are opposite. The breaking unit of the DC circuit breaker effectively improves the flexibility and reliability of breaking current of the circuit breaker by connecting multiple single-channel branches in parallel.

Description

A New Hybrid DC Circuit Breaker and Power Unit

technical field

The invention relates to a novel hybrid direct current circuit breaker and a power unit, belonging to the technical field of direct current transmission.

Background technique

The multi-terminal DC transmission and DC grid technology based on flexible DC is of great significance for greatly improving the ability of the grid to accept renewable energy and realizing the long-distance deployment of renewable energy. With the increase of DC grid voltage and transmission capacity, there are higher requirements for the flexibility and reliability of DC circuit breaker breaking current.

The invention patent "a hybrid DC circuit breaker topology" with the publication number CN105609344A discloses a DC circuit breaker topology. The solid-state switch S of this topology includes several IGBT modules connected in series, and each IGBT module consists of two It is composed of two IGBTs in reverse series to realize bidirectional turn-off fault current. However, since multiple IGBT modules are connected in series, when any one of the IGBTs fails, the circuit breaker no longer has the ability to cut off in the direction in which the IGBT is turned on. When any two reverse-conducting IGBTs fail, the circuit breaker The circuit breaker no longer has the cut-off function, and the reliability and flexibility of the circuit breaker to break the fault current are poor.

Therefore, based on the above analysis, how to quickly isolate the fault while enhancing the flexibility and reliability of breaking the fault current has become a key issue in the research of hybrid HVDC circuit breakers.

Contents of the invention

The purpose of the present invention is to propose a new type of hybrid DC circuit breaker and power unit, which is used to solve the problem that the DC circuit breaker is connected in series with fully controlled power devices, resulting in poor reliability and flexibility in breaking the fault current of the DC circuit breaker .

In order to solve the problems of the technologies described above, the present invention includes:

A power unit, the power unit includes at least one forward channel branch and at least one reverse channel branch connected in parallel; the forward channel branch and the reverse channel branch each include a full A controlled power device and a diode, the conduction directions of the forward channel branch and the reverse channel branch are opposite.

Further, the power unit further includes a capacitor branch; the capacitor branch includes a capacitor, and the capacitor branch is connected in parallel with the forward channel branch and the reverse channel branch.

Further, the power unit further includes a bidirectional channel branch, and the bidirectional channel branch includes two fully-controlled power devices in reverse series.

Further, the fully-controlled power device is an IGBT or an IGCT.

A novel hybrid direct current circuit breaker, the direct current circuit breaker includes a commutation branch connected in parallel, a breaking branch and an energy absorption branch; the commutation branch includes a mechanical switch and at least one commutation unit, The breaking branch includes several breaking units connected in series, wherein the breaking unit adopts a specific power unit structure, and the specific power unit structure includes at least one forward channel branch connected in parallel and at least one reverse channel branch, the forward channel branch and the reverse channel branch both include a fully-controlled power device and a diode connected in series in the same direction, the forward channel branch and the reverse channel branch The conduction direction of the road is opposite.

Further, the specific power unit structure further includes a capacitor branch, the capacitor branch includes a capacitor, and the capacitor branch is connected in parallel with the forward channel branch and the reverse channel branch.

Further, the specific power unit structure also includes a bidirectional channel branch, and the bidirectional channel branch includes two fully-controlled power devices in reverse series.

Further, the converter unit adopts the specific power unit structure.

Further, the fully-controlled power device is an IGBT or an IGCT.

The beneficial effects of the present invention are:

Compared with other solutions in the prior art, the power unit of the present invention adopts the parallel connection mode of the forward channel branch and the reverse channel branch, which enhances the reliability and flexibility of the circuit. When the power unit includes multiple forward channel branches and reverse channel branches, the ability of the novel hybrid DC circuit breaker to cut off the fault current can be effectively improved.

In addition, the power unit also includes a parallel capacitor branch for absorbing the fault current, which can effectively reduce the damage effect of the fault current on the power device and correspondingly improve the service life of the DC circuit breaker.

Description of drawings

Fig. 1 is the power unit topology in embodiment 1;

Fig. 2 is the power unit topology in embodiment 2;

Fig. 3 is the power unit topology in embodiment 3;

Fig. 4 is the power unit topology in embodiment 4;

Figure 5 is a new hybrid DC circuit breaker topology.

detailed description

The present invention proposes a new type of hybrid DC circuit breaker and power unit, the main improvement of which is: multiple forward channel branches and reverse channel branches are connected in parallel, and a capacitor branch is connected in parallel, which enhances the hybrid The flexibility and reliability of the wiring of the DC circuit breaker avoids the impact loss of the fault current on the power device. The present invention will be further described in detail in conjunction with the accompanying drawings.

Embodiment 1 of a power unit;

Referring to Fig. 1, the power unit includes a forward channel branch and a reverse channel branch connected in parallel, wherein the forward channel branch is composed of IGBT (1) and diode (2), and the reverse channel branch is composed of IGBT (4 ) and diode (3), and a diode is connected in antiparallel to both ends of IGBT (1) and IGBT (4), where the conduction direction of the forward channel branch is along the direction of the arrow in Figure 1, and the conduction direction of the reverse channel branch is The conduction direction is opposite to that of the forward channel branch.

Embodiment 2 of a power unit;

Referring to Fig. 2, the power unit includes a capacitor branch, a forward channel branch and a reverse channel branch connected in parallel; the capacitor branch includes a capacitor (9), and the forward channel branch is composed of IGBT (5) and Diode (6), the reverse channel branch is composed of IGBT (8) and diode (7), and the two ends of IGBT (5) and IGBT (8) are respectively anti-parallel with a diode, wherein the conduction of the forward channel branch The direction is along the direction of the arrow in FIG. 2 , and the conduction direction of the reverse channel branch is opposite to that of the forward channel branch.

Embodiment 3 of a power unit;

With reference to Fig. 3, this power unit comprises a capacitor branch, a forward channel branch, a reverse channel branch and a two-way channel branch connected in parallel; Wherein, the capacitor branch comprises a capacitor (16), forward The channel branch is composed of IGBT (10) and diode (11) in series in the same direction, the reverse channel branch is composed of IGBT (15) and diode (14) in series in the same direction, and the bidirectional channel branch is composed of IGBT (12) and IGBT (13) Composed of anti-series, IGBT (10), IGBT (12), IGBT (13) and IGBT (15) are connected in anti-parallel with a diode at both ends, wherein the conduction direction of the forward channel branch is along the direction of the arrow in Figure 3, and the anti-parallel The conduction direction of the forward channel branch is opposite to the conduction direction of the forward channel branch.

Embodiment 4 of a power unit;

With reference to Fig. 4, this power unit comprises a capacitor branch, two forward channel branches and two reverse channel branches connected in parallel; Wherein, the capacitor branch comprises a capacitor (25), the first forward channel The branch is composed of IGBT (17) and diode (18) in series in the same direction, the second forward channel branch is composed of IGBT (19) and diode (20) in series in the same direction, and the first reverse channel branch is composed of IGBT (22) and the diode (21) in the same direction in series, and the second reverse channel branch is composed of the IGBT (24) and the diode (23) in the same direction in series, wherein the conduction direction of the forward channel branch is along the direction of the arrow in Figure 4, and the opposite The conduction direction of the forward channel branch is opposite to the conduction direction of the forward channel branch.

In addition, the IGBTs in the above four power unit embodiments can also be replaced by other fully-controlled devices, such as IGCTs.

Referring to the method of increasing the bidirectional channel branch in embodiment 3 and the method of increasing the forward channel branch and the reverse channel branch in embodiment 4, if necessary, more parallel connections can also be similarly added in the power unit Forward channel branch, reverse channel branch and bidirectional channel branch to enhance the flow capacity and flexibility of the unit module.

Embodiment of a new hybrid DC circuit breaker;

Referring to Fig. 5, the DC circuit breaker includes a commutating branch, a breaking branch and an energy absorbing branch connected in parallel. Wherein, the commutation branch includes a mechanical switch and several commutation units, the breaking branch includes several series-connected breaking units, and the energy absorbing branch includes a lightning arrester unit.

Wherein, the breaking unit adopts any power unit structure in the above-mentioned power unit embodiments 1 to 4. Since the introduction of the power unit structure has been given in detail in the above content, it will not be repeated here.

In addition, the converter unit can adopt any power unit structure in the above-mentioned power unit embodiments 1 to 4, or can adopt the H-bridge structure or the half-bridge structure in the prior art, and the number of converter units is smaller than that of the breaking unit .

The working principle of the new hybrid DC circuit breaker:

When the DC power grid fails and the DC circuit breaker issues a breaking command, the IGBT in the breaking unit is turned on, and the IGBT in the converter unit is turned off. When all the current is transferred to the breaking branch, the fast mechanical switch is broken. When the opening distance of the mechanical switch is large enough, the IGBT in the breaking unit is turned off, and the fault current charges the capacitor connected in parallel in the breaking unit. When the capacitor voltage reaches the action threshold of the arrester, the arrester operates to consume the fault current, DC The circuit breaker is opened.

Claims (10)

1. a power cell, it is characterised in that described power cell includes at least one forward channel branch road being connected in parallel With at least one backward channel branch road；Described forward channel branch road and backward channel branch road all comprise a full control of series aiding connection Type power device and a diode, the conducting direction of described forward channel branch road and backward channel branch road is contrary.

Power cell the most according to claim 1, it is characterised in that described power cell also includes a capacitive branch, Described capacitive branch includes an electric capacity, described capacitive branch and described forward channel branch road and described backward channel branch circuit parallel connection Connect.

Power cell the most according to claim 1 and 2, it is characterised in that described power cell also includes a two-way Road branch road, described duplex channel branch road includes the full-control type power device of two differential concatenations.

Power cell the most according to claim 1 and 2, it is characterised in that described full-control type power device be IGBT or IGCT。

5. a novel mixed type dc circuit breaker, described dc circuit breaker includes the change of current branch road being connected in parallel, cut-offs branch road With energy absorption branch road；Described change of current branch road includes a mechanical switch and at least one convertor unit, described in cut-off branch road bag Include that several are connected in series cut-offs unit, it is characterised in that described in cut-off unit and use a kind of particular power cell structure, institute State at least one forward channel branch road and at least one backward channel branch road, institute that particular power cell structure includes being connected in parallel State forward channel branch road and backward channel branch road all comprises a full-control type power device and a diode, the institute of series aiding connection The conducting direction stating forward channel branch road and backward channel branch road is contrary.

Novel mixed type dc circuit breaker the most according to claim 5, it is characterised in that described particular power cell structure Also including a capacitive branch, described capacitive branch includes an electric capacity, described capacitive branch and described forward channel branch road and Described backward channel branch circuit parallel connection connects.

7. according to the novel mixed type dc circuit breaker described in claim 5 or 6, it is characterised in that described particular power cell Structure also includes that a duplex channel branch road, described duplex channel branch road include the full-control type power device of two differential concatenations.

8. according to the novel mixed type dc circuit breaker described in claim 5 or 6, it is characterised in that described convertor unit uses Described particular power cell structure.

Novel mixed type dc circuit breaker the most according to claim 7, it is characterised in that described convertor unit uses described Particular power cell structure.

10. according to the novel mixed type dc circuit breaker described in claim 5 or 6, it is characterised in that described full-control type power device Part is IGBT or IGCT.