Subsea power distribution system and method

1. A subsea power distribution system, comprising:

a power input to receive electrical power at a first voltage level;

an input transformer coupled to the power input and adapted to transform received electrical power to a second voltage level which is relatively lower than the first voltage level;

a distribution circuit to distribute received electrical power to two or more power distribution paths; and

at least one rectifier unit to receive transformed electrical power from the input transformer and output rectified electrical power, wherein each of the two or more power distribution paths includes

an inverter configured to receive rectified electrical power from the rectifier unit and to output AC electrical power at a third voltage level,

a distribution path transformer coupled to the respective inverter and configured to transform the output AC electrical power to a fourth voltage level which is relatively higher than the third voltage level,

a separate breaker or switch,

a cable,

a load, and

a power output to provide the transformed AC electrical power to a subsea load.

2. The subsea power distribution system of claim 1 , wherein the power input, the input transformer, the distribution circuit and the at least one rectifier unit form part of a subsea power distribution unit, and wherein each of the two or more power distribution paths includes a subsea drive unit including the respective inverter, distribution path transformer and power output, the subsea power distribution unit and the subsea drive unit being connected via wet-mateable subsea connectors.

3. The subsea power distribution system of claim 2 , wherein each of the two or more power distribution paths includes an intermediate power output provided at the subsea power distribution unit, an intermediate power input at the subsea drive unit, and a subsea cable connection between the intermediate power output and the intermediate power input for transmitting electrical power, wherein the subsea power distribution unit and the two or more subsea drive units each include a separate subsea enclosure.

4. The subsea power distribution system of claim 2 , wherein the subsea power distribution system is configured to distribute electrical power to subsea well equipment located at different subsea wellheads, wherein the two or more subsea drive units include a first subsea drive unit located in proximity to a first wellhead and a second subsea drive unit located in proximity to a different second wellhead.

5. The subsea power distribution system of claim 1 , wherein the rectifier unit is connected between an output of the input transformer and the distribution circuit, the distribution circuit being a DC distribution circuit, each of the two or more power distribution paths being supplied with rectified electrical power from said rectifier unit via the DC distribution circuit.

6. The subsea power distribution system of claim 1 , wherein the power distribution system comprises a rectifier unit for each of the two or more power distribution paths.

7. The subsea power distribution system of claim 6 , wherein the rectifier unit and the inverter of a respective one of the two or more power distribution paths form a frequency converter unit, in particular a variable speed drive.

8. The subsea power distribution system of claim 1 , wherein the first voltage level is a medium voltage level.

9. The subsea power distribution system of claim 1 , wherein the second voltage level and the third voltage level each is within a range of about 200 V to about 5,000 V.

10. The subsea power distribution system of claim 1 , wherein the fourth voltage level is within a range of about 1,000 V to about 10,000 V.

11. The subsea power distribution system of claim 1 , wherein each of the two or more power distribution paths includes a semiconductor switch.

12. The subsea power distribution system of claim 11 , wherein the semiconductor switch is controllable to control the output electrical power provided at the power output of a respective one of the two or more power distribution paths.

13. The subsea power distribution system of claim 1 , further comprising a controller adapted to control at least the inverters of the two or more power distribution paths.

14. The subsea power distribution system of claim 1 , wherein the distribution circuit is a DC distribution circuit, wherein the first voltage level is a medium or high voltage level, wherein the DC distribution occurs at a low voltage level, and wherein the fourth voltage level, at which the electric power is provided to the load, is a medium voltage level.

15. The subsea power distribution system of claim 4 , wherein the subsea power distribution system is configured to distribute electrical power to electric submersible pumps.

16. The subsea power distribution system of claim 3 , wherein the subsea power distribution system is configured to distribute electrical power to subsea well equipment located at different subsea wellheads, wherein the two or more subsea drive units include a first subsea drive unit located in proximity to a first wellhead and a second subsea drive unit located in proximity to a different second wellhead.

17. The subsea power distribution system of claim 16 , wherein the subsea power distribution system is configured to distribute electrical power to electric submersible pumps.

18. The subsea power distribution system of claim 7 , wherein the frequency converter unit is a variable speed drive.

19. The subsea power distribution system of claim 8 , wherein the first voltage level is a voltage level between about 1,000 V and about 80,000 Volt.

20. The subsea power distribution system of claim 9 , wherein the second voltage level and the third voltage level each is within a range of about 500 V to about 4,000 V.

21. The subsea power distribution system of claim 10 , wherein the fourth voltage level is within a range of about 1,500 V to about 6,000 V.

22. The subsea power distribution system of claim 19 , wherein the second voltage level and the third voltage level each is within a range of about 200 V to about 5,000 V.

23. The subsea power distribution system of claim 22 , wherein the fourth voltage level is within a range of about 1,000 V to about 10,000 V.

24. The subsea power distribution system of claim 11 , wherein each of the two or more power distribution paths further includes a mechanical switch.

25. The subsea power distribution system of claim 24 , wherein the mechanical switch is a contactor.

26. A method of operating a subsea power distribution system, the method comprising:

receiving input electrical power at a first voltage level on a power input;

transforming received electrical power to a second voltage level which is relatively lower than the first voltage level via a distribution transformer;

distributing received electrical power to two or more power distribution paths via a distribution circuit;

rectifying transformed electrical power given out by the input transformer via a rectifier unit which gives out rectified electrical power; and

for each of the two or more power distribution paths, performing the following:

receiving electrical power at a separate breaker or switch,

outputting the received electrical power to a cable,

inverting the rectified electrical power given out by the rectifier unit to obtain AC electrical power at a third voltage level via an inverter,

transforming the AC electrical power to a fourth voltage level which is relatively higher than the third voltage level via a distribution path transformer, and

providing the transformed AC electrical power to a subsea load via a power output.