Subsea transformer with integrated high resistance ground

Patent metadata

Field	Value
Publication number	US-2016247618-A1
Application number	US-201514631676-A
Country	US
Kind code	A1
Filing date	Feb 25, 2015
Priority date	Feb 25, 2015
Publication date	Aug 25, 2016
Grant date	—

Abstract

According to some embodiments, a subsea transformer is protected by an integrated high resistance grounding (HRG) device. The active components, including primary and secondary sets of windings for the transformer are mounted in an oil-filled transformer tank that is suitable for long-term deployment in a subsea environment. The HRG device is mounted in the same oil-filled transformer tank as the active transformer components.

First claim

What is claimed is:

1 . A subsea transformer protected by resistance grounding comprising:
a primary set of coil windings; a secondary set of coil windings; a subsea transformer tank defined by a tank wall and housing said primary and secondary sets of coil windings and a transformer fluid which bathes said primary and secondary sets of coil windings, said tank wall being suitable for deployment in a subsea environment; and a resistance grounding device mounted within said transformer tank and being bathed in the transformer fluid, and comprising:
a first terminal electrically connected to a neutral node of said secondary set of coil windings; and
a second terminal electrically connected to a ground, said resistance grounding device configured to provide electrical resistance path between said first and second terminals.

2 . The subsea transformer according to claim 1 wherein an outer surface of the tank wall is exposed to seawater and an inner surface of the tank wall is exposed to the transformer fluid.

3 . The subsea transformer according to claim 1 wherein said resistance electrical path has a resistance of at least 1000 ohms.

4 . The subsea transformer according to claim 1 wherein said resistance electrical path includes a plurality of resistance elements electrically interconnected in series.

5 . The subsea transformer according to claim 4 wherein said plurality of resistance elements are grouped into a plurality of banks, each of which is mounted to a frame member of said transformer.

6 . The subsea transformer according to claim 1 wherein the transformer fluid is an insulating transformer oil.

7 . The subsea transformer according to claim 1 wherein the transformer is a step-down or a step-up transformer.

8 . The subsea transformer according to claim 1 wherein the subsea transformer is a step-down transformer, said primary set of windings are interconnected in a delta arrangement, and said secondary set of windings are interconnected in a wye arrangement.

9 . The subsea transformer according to claim 1 wherein said first and second terminals are electrically connected to said neutral node and said ground, respectively, via low resistance electrical paths.

10 . The subsea transformer according to claim 1 wherein said ground is the tank wall.

11 . The subsea transformer according to claim 1 wherein said transformer is configured to supply power to one or more subsea components used for processing hydrocarbon fluids produced from a subterranean rock formation.

12 . The subsea transformer according to claim 11 wherein said one or more subsea components are motors configured for driving one or more subsea pumps, compressors or separators.

Assignees

• Onesubsea Ip Uk Ltd

Inventors

• Diesen Asbjoern

Classifications

• H01F27/12

  Oil cooling · CPC title

• H02H9/08

  Limitation or suppression of earth fault currents, e.g. Petersen coil · CPC title

• H01F27/34 Primary

  Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields · CPC title

• H01F27/28

  Coils; Windings; Conductive connections · CPC title

• H01F27/02 Primary

  Casings · CPC title