SYSTEM FOR SUBSEA PRESSURE BOOSTER POWER SUPPLY AND DISTRIBUTION, METHOD FOR OPERATION AND USE THEREOF

Abstract

The invention provides a system for subsea pressure booster HV (high voltage), MV (medium voltage) and LV (low voltage) power supply and distribution. The system is distinguished in that the system consists of, essentially consists of or comprises: a supply cable without a connected variable speed drive/variable frequency drive (VSD, VFD); at least one subsea pressure booster, and; one subsea direct online switch (SDOS) for each subsea pressure booster, wherein the supply cable at a source end is coupled to an AC power source at a topside, onshore or subsea location, wherein the supply cable at a pressure booster end is coupled directly or via a distribution device to at least one subsea direct online switch, SDOS, wherein each SDOS is coupled to one subsea pressure booster. Method of operation and use of the system.

Claims

1. A system for subsea pressure booster power supply and distribution, the system comprising: a supply cable without a connected variable speed drive/variable frequency drive (VSD, VFD); at least one subsea pressure booster; one subsea direct online switch (SDOS) for each subsea pressure booster; wherein the supply cable at a source end is coupled to an AC power source at a topside, onshore or subsea location; wherein the supply cable at a pressure booster end is coupled directly or via a distribution device to at least one subsea direct online switch, SDOS; and wherein each SDOS is coupled to one subsea pressure booster.

2. The system according to claim 1, comprising at least two subsea pressure boosters and liquid filled subsea direct online switches with pressure compensator, coupled via a distribution device to the pressure booster end of the supply cable.

3. The system according to claim 1, wherein the distribution device is a subsea transformer, with one primary winding coupled to the supply cable and one secondary winding for each subsea pressure booster, with each secondary winding coupled to a liquid filled subsea direct online switch with pressure compensator, SDOS, coupled to a subsea pressure booster, with the transformer arranged in a liquid filled and pressure compensated housing and each SDOS arranged in a separate housing, with remotely wet mate able connectors in between the housings.

4. The system according to claim 1, wherein the distribution device is a distribution box, coupled with remotely wet mate able connectors to one liquid filled subsea direct online switch with pressure compensator for each subsea pressure booster.

5. The system according to claim 1, wherein each SDOS and distribution device is arranged in a liquid filled housing comprising a pressure balancing device for balancing the pressure inside the housing to outside ambient pressure, and with feedthroughs/penetrators of low pressure LP type or medium pressure MP type.

6. The system according to claim 1, wherein each subsea pressure booster comprises a hydraulic variable speed drive or torque converter or clutch and gear device, for adjusting the speed of the pressure booster from 0 or near 0 to a maximum, which maximum preferably is at least 1,6 times higher with respect to rpm than for a motor of the subsea pressure booster, preferably at least twice the motor rpm.

7. A method of operating a system according to claim 1, comprising: connecting a subsea direct online switch with pressure compensator, SDOS, in order to start the pressure booster coupled to the SDOS; and disconnecting the SDOS to stop the pressure booster.

8. The method according to claim 7, wherein the steps include sending a control signal via a control link, for opening or closing the SDOS by an actuator integrated or operatively connected to the SDOS.

9. The method according to claim 7, wherein the system comprises at least two pressure boosters with a hydraulic variable speed drive or torque converter or clutch and gear device coupling motor to pump or compressor wherein pressure boosters are started sequentially by closing a first SDOS and when a first pressure booster motor has finished the startup current transient, close a second SDOS and when a second pressure booster motor has finished the startup current transient start further pressure booster motors sequentially and likewise; with the pressure booster motors rotating stable, couple in a first pressure booster pump or compressor, when the first pressure booster pump or compressor rotates stable, couple in a second pressure booster pump or compressor, and couple in further pumps or compressors sequentially and likewise.

10. (canceled)

11. The system according to claim 3, comprising remotely wet mate able connectors in between each SDOS and pressure booster.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0035] FIGS. 1 and 2 illustrate embodiments of a system of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Reference is made to FIG. 1, illustrating an embodiment of the system 1 of the invention with three subsea pressure boosters 2. A distribution device 3 in the form of a transformer or a distribution box is arranged on the seabed in a pressure booster end of the supply cable 4. One liquid filled subsea direct online switch with pressure compensator (SDOS) 5 for each subsea pressure booster is arranged, between the distribution device and each subsea pressure booster. The supply cable is extending from a source end 6, on an FPSO (floating production, storage and offloading vessel), to a pressure booster end 7 on the seabed.

[0037] The figures are illustrative for essential components only and are out of scale for improved clarity.

[0038] Reference is made to FIG. 2, illustrating an embodiment of the system 1 of the invention with one subsea pressure booster 2. At the subsea pressure booster end of the supply cable 4, a SDOS 5 is arranged between the supply cable and the subsea pressure booster 2.

[0039] Benefits of the system, methods and use of the invention include, but are not limited to: [0040] Simpler HV power supply system—no VSD required (neither topside nor subsea), including associated equipment including cooling (HVAC) and EX protection and noise filtering equipment. [0041] Longer step-outs—Damaging noise is normally amplified with distance when pumps are operated by VSD and connected by long subsea cables. [0042] No-load start of motor—In preferable embodiments the motor is hydraulically or by a clutch device decoupled from the pump or compressor of the subsea pressure booster [0043] Soft start—Less mechanical wear [0044] Full-range Variable Speed functionality, preferably embedded in the Pump Unit itself—By means of variable angle or position guide vanes or other means controlling fluid flow inside the Torque Converter [0045] Rapid response to changes in process conditions—Preferable torque converter holds transferred power (kW) constant at any given guide vane position and provides immediate and soft response to any transient [0046] Rotodynamic stability—Motor can operate at lower speeds than the pump—which gives less vibrations [0047] Low motor speed operation—Reduces friction losses on the motor leading to increased motor efficiency for high speed pump applications [0048] Reduced cost [0049] Improved reliability due to reduced number of components that can fail. [0050] Reduced overcurrent due to individual start of motor and subsequent individual start/coupling of pump/compressor. [0051] Avoid pressure housing/canisters rated to hundreds of bars differential pressure over the housing wall. [0052] Provide a simplified design nearly independent of water depth, voltage and current rating. [0053] Replaceable components, individually or in groups, preferably by unmanned intervention, aided only by an ROV-remotely operable vehicle, or a ROT-remotely operable tool, deployable and controlled from a vessel. [0054] Low pressure LP or medium pressure MP penetrators and feedthroughs.