Variable speed drive for subsea applications
A Variable Speed Drive ( 1 ) for subsea installations ( 20 ), subsea vessels or subsea vehicles, as well as to a corresponding subsea installation ( 20 ), subsea vessel or subsea vehicle, has an alternating current/alternating current converter ( 2 ) having a current-controlled capacitor-less direct current link ( 7 ).
1. A variable speed drive (VSD) for subsea installations, comprising:
an alternating current/alternating current converter;
a liquid-tight housing in which at least the converter is arranged;
wherein the housing is filled with an electrically isolating liquid; and
a volume compensator provided for the housing;
wherein the converter is equipped with power electronic switches, and wherein the converter is indirectly exposed to subsea environmental pressure, wherein the volume compensator provides the electrically isolating liquid with an overpressure with respect to a surrounding subsea pressure.
2. A variable speed drive (VSD) for subsea installations, comprising:
an alternating current/alternating current converter;
a liquid-tight housing in which at least the converter is arranged;
wherein the housing is filled with an electrically isolating liquid; and
a volume compensator provided for the housing;
wherein the converter is equipped with power electronic switches, and wherein the converter is indirectly exposed to subsea environmental pressure, wherein a differential pressure between an interior of the housing and an exterior of the housing is negligible.
3. The variable speed drive of claim 1 , wherein the electrically isolating liquid acts as a coolant to dissipate waste heat from electronics of the converter.
4. The variable speed drive of claim 1 , wherein the alternating current/alternating current converter has a current-controlled capacitor-less direct current link.
5. The variable speed drive of claim 4 , wherein the direct current link comprises a smoothing inductor.
6. The variable speed drive of claim 4 , wherein the direct current link consists of a smoothing inductor.
7. The variable speed drive of claim 1 , wherein a wall of the housing has a thickness of maximally 10 mm.
8. The variable speed drive of claim 1 , wherein the housing is directly exposed to seawater.
9. The variable speed drive of claim 1 , wherein the housing is arranged within a liquid-tight main vessel.
10. The variable speed drive of claim 9 , wherein the main vessel is at least partially filled with the electrically isolating liquid or another electrically isolating liquid.
11. The variable speed drive of claim 1 , wherein the converter comprises a thyristor-controlled rectifier and a thyristor-controlled line-commutated inverter.
12. A variable speed drive (VSD) for subsea installations, comprising:
an alternating current/alternating current converter;
a liquid-tight housing in which at least the converter is arranged;
wherein the housing is filled with an electrically isolating liquid; and
a volume compensator provided for the housing;
wherein the converter is equipped with power electronic switches, and wherein the converter is indirectly exposed to subsea environmental pressure, further comprising a separate air-filled containment comprising control electronics of the converter.
13. The variable speed drive of claim 12 , wherein the air-filled containment is arranged inside the housing.
14. A variable speed drive (VSD) for subsea installations, comprising:
an alternating current/alternating current converter;
a liquid-tight housing in which at least the converter is arranged;
wherein the housing is filled with an electrically isolating liquid; and
a volume compensator provided for the housing;
wherein the converter is equipped with power electronic switches, and wherein the converter is indirectly exposed to subsea environmental pressure, wherein the volume compensator is located on or inside the housing.
15. The variable speed drive of claim 1 , wherein the power electronic switches are selected from the group consisting of thyristors, metal oxide semiconductor field effect transistors, and insulated gate bipolar transistors.
16. A subsea installation, comprising:
a variable speed drive (VSD) comprising:
an alternating current/alternating current converter;
a liquid-tight housing in which at least the converter is arranged;
wherein the housing is filled with an electrically isolating liquid; and
a volume compensator provided for the housing;
wherein the converter is equipped with power electronic switches, and wherein the converter is indirectly exposed to subsea environmental pressure, wherein a differential pressure between an interior of the housing and an exterior of the housing is negligible.
17. A variable speed drive (VSD) for subsea installations, comprising:
an alternating current/alternating current converter;
a liquid-tight housing in which at least the converter is arranged;
wherein the housing is filled with an electrically isolating liquid; and
a volume compensator for the housing, the volume compensator configured to provide a pressure inside said housing substantially similar to a subsea environmental pressure when the variable speed drive is installed subsea;
wherein the converter is equipped with power electronic switches and is disposed in the electrically isolating liquid in the housing, such that the converter and the power electronic switches are indirectly exposed to the subsea environmental pressure.
18. The variable speed drive of claim 17 , wherein the converter comprises a power electronic switch-controlled rectifier and a power electronic switch-controlled line-commutated inverter.
19. The variable speed drive of claim 17 , wherein the power electronic switches are selected from the group consisting of thyristors, metal oxide semiconductor field effect transistors, and insulated gate bipolar transistors.