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, wherein the system essentially consists of: a supply cable; at least one subsea pressure booster comprising a motor driving a pump or compressor; one subsea direct online switch (SDOS) for the at least one subsea pressure booster, wherein the SDOS comprises a linear, a rotary or a combined linear-rotary actuator coupled to a control link for opening or closing the SDOS, for stop or start of the at least one subsea pressure booster, independently from a power supply control system; 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 the SDOS; wherein the SDOS is coupled to the motor of the at least one subsea pressure booster; wherein the supply cable, between the AC power source and the motor of the at least one subsea pressure booster, is without a connected variable speed drive (VSD) and without a variable frequency drive (VFD); and wherein the distribution device is a subsea transformer comprising one primary winding coupled to the supply cable and one secondary winding for the at least one subsea pressure booster, coupled to a liquid filled subsea direct online switch (SDOS) with a pressure compensator, coupled to the at least one subsea pressure booster, with the subsea transformer arranged in a liquid filled and pressure compensated housing and the SDOS arranged in a separate housing, with remotely wet mate able connectors in between the housings.

2. The system according to claim 1, wherein the at least one subsea pressure booster comprises a hydraulic variable speed drive or torque converter or clutch and gear device, for adjusting a speed of the pump or compressor of the at least one subsea pressure booster from 0 or near 0 to a maximum, which maximum of at least 1.6 times higher with respect to rpm than for a motor of the at least one subsea pressure booster, or at least twice the motor rpm.

3. The system according to claim 1, comprising remotely wet mate able connectors in between the SDOS and the at least one subsea pressure booster.

4. A method of operating a system according to claim 1, comprising: connecting the subsea direct online switch with pressure compensator (SDOS), in order to start the at least one subsea pressure booster coupled to the SDOS; disconnecting the SDOS to stop the at least one subsea pressure booster; wherein the step includes sending a control signal via a control link, for opening or closing the SDOS by an actuator integrated or operatively connected to the SDOS; wherein the system comprises: at least two pressure boosters with a hydraulic variable speed drive or torque converter or clutch and gear device coupling the motor to the pump or compressor, wherein the at least two pressure boosters are started sequentially by closing a first SDOS and when a first pressure booster motor has finished a startup current transient, close a second SDOS and when a second pressure booster motor has finished a startup current transient start further pressure booster motors sequentially and likewise; and with the first and second 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.

5. A system for subsea pressure booster power supply and distribution, wherein the system essentially consists of: a supply cable; at least one subsea pressure booster comprising a motor driving a pump or compressor; one subsea direct online switch (SDOS) for the at least one subsea pressure booster; wherein the SDOS comprises a linear, a rotary or a combined linear-rotary actuator, coupled to a control link for opening or closing the SDOS, for stop or start of the at least one subsea pressure booster, independently from a power supply control system; 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 the SDOS; wherein the SDOS is coupled to the motor of the at least one subsea pressure booster; wherein the supply cable, between the AC power source and the motor of the at least one subsea pressure booster, is without a connected variable speed drive (VSD) and without a variable frequency drive (VFD); and wherein the at least one subsea pressure booster comprises a hydraulic variable speed drive or torque converter or clutch and gear device, arranged between the motor and the pump or compressor.

6. The system of claim 5, comprising a plurality of subsea pressure boosters, each subsea pressure booster of the plurality of subsea pressure boosters is operatively coupled to a distribution device via the SDOS.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1 and 2 illustrate embodiments of a system of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(2) 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.

(3) The figures are illustrative for essential components only and are out of scale for improved clarity.

(4) 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.

(5) Benefits of the system, methods and use of the invention include, but are not limited to: Simpler HV power supply systemno VSD required (neither topside nor subsea), including associated equipment including cooling (HVAC) and EX protection and noise filtering equipment. Longer step-outsDamaging noise is normally amplified with distance when pumps are operated by VSD and connected by long subsea cables. No-load start of motorIn preferable embodiments the motor is hydraulically or by a clutch device decoupled from the pump or compressor of the subsea pressure booster Soft startLess mechanical wear Full-range Variable Speed functionality, preferably embedded in the Pump Unit itselfBy means of variable angle or position guide vanes or other means controlling fluid flow inside the Torque Converter Rapid response to changes in process conditionsPreferable torque converter holds transferred power (kW) constant at any given guide vane position and provides immediate and soft response to any transient Rotodynamic stabilityMotor can operate at lower speeds than the pumpwhich gives less vibrations Low motor speed operationReduces friction losses on the motor leading to increased motor efficiency for high speed pump applications Reduced cost Improved reliability due to reduced number of components that can fail. Reduced overcurrent due to individual start of motor and subsequent individual start/coupling of pump/compressor. Avoid pressure housing/canisters rated to hundreds of bars differential pressure over the housing wall. Provide a simplified design nearly independent of water depth, voltage and current rating. 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. Low pressure LP or medium pressure MP penetrators and feedthroughs.