Patent Application
20120057308
The present application relates generally to electrical power deliver systems and more particularly relates to modular stacked power converter vessels for sub-sea power delivery by direct current (DC) power transmission.
Transportation of electrical power to, for example, oil, gas, or other types of sub-sea electrical equipment, often requires low or high power to be transported over any type of distance to serve one or multiple loads. Electrical power delivery systems for offshore or sub-sea electrical loads generally use a DC (direct current) transmission bus or cable. The receiving end and the sending end of the DC transmission bus may include modular stacked power converters that are largely symmetrical in structure. The configuration of the modular stacked power converters preferably may be expandable and reconfigurable based upon local load requirements and changes.
In modular stacked high voltage DC power transmission and distribution topologies, DC to AC (alternating current) converter modules and the like may be designed for a nominal DC voltage of a few kilovolts, e.g., only about five (5) kilovolts. These modules, however, also may need to be insulated for high voltages, e.g., about fifty (50) kilovolts against the ground potential. This requirement may be difficult to fulfill with typical high voltage engineering designs where all metallic screens or vessels are typically at one potential, e.g., ground potential. Much more electrical insulation space may be required with the typical complex and multipart converter designs. As a result, complex sub-sea converter systems cannot be efficiently marinized or optimized from a high voltage engineering design point of view.
There is thus a desire for optimized packaging and grounding systems and methods for modular stacked high voltage, direct current power transmission systems for sub-sea use. Such systems and methods may provide optimum power delivery with low system costs and complexity, high system reliability and maintainability, high efficiency, and high power density.
The present application thus provides a modular stacked power converter vessel. The modular stacked power converter vessel may include an inner container at a first potential, a modular stacked power converter positioned within the inner container, and an outer container. The outer container surrounds the inner container and may be at a second potential.
The present application further provides a modular stacked power converter vessel. The modular stacked power converter vessel may include an inner container, a modular stacked power converter positioned within the inner container, and an outer container surrounding the inner container. The modular stacked power converter may have a converter potential and the inner container may have about the converter potential. The outer container may have a ground potential.
The present application further provides a marinized high voltage direct current system for sub-sea DC power transmission and distribution. The marinized high voltage direct current system may include a first module at a first potential, a second module at a second potential, and an electrical connection between the first module and the second module. The first module and the second module both may include a number of modular stacked power converters therein. Each of the modular stacked power converters may be positioned within a modular stacked power converter vessel. The modular stacked power converter vessel may include an inner container within an outer container.
These and other features and improvements of the present application will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.
Referring now to the drawings, in which like numerals refer to like elements throughout the several view,
Each of the transformers 150 may be in connection with a number of the modular stacked power converters 110. In this example, the modular stacked power converters 110 may take the form of a number of AC to DC power converters 160. Any number or configuration of the AC to DC power converters 160 may be used herein. The AC to DC power converters 160 convert the AC current to high voltage DC current. A number of chopper modules 170 may be used with the AC to DC power converters 160. The chopper modules 170 may be configured to operate as bypass switches if necessary. The AC to DC power converters 160 may be in connection with one or more high voltage direct current (HVDC) buses or cables 180. Other configurations also may be used herein.
A cooling system 390 may be positioned between the inner container 360 and the outer container 370 and in connection with the modular stacked power converter 110. The cooling system 390 as positioned inside the inner container 370 may not be exposed to higher potential differences as compared to standard drive systems. Other configurations and other components may be used herein.
The shape of the modular stacked power converter vessel 350 may accommodate the pressures of deep-sea applications such as by using a spherical or a cylindrical shape 400. Other shapes and/or combinations of shapes may be used herein. The inner container 360 and the outer container 370 may define a space 410 therebetween. The space 410 may be filled with a medium 420 such as an insulating material with high mechanical strength, e.g., an epoxy resin or a glass fiber reinforced plastic. The medium 420 also may be a gas with an optimum voltage withstanding capability, e.g., an insulating oil, sulfur hexafluoride (“SF6”), and the like. The medium 420 also may provide sufficient thermal conductivity, i.e., transfer of heat created by electrical losses to the outer container 370. Alternatively, the heat transfer may be provided by cooling tubes with a suitable cooling fluid, e.g., de-ionized water, where the cooling system is designed to withstand the DC high voltage that exists between the inner and the outer vessels. The space 410 may have any desired size. Other types of mediums 420 may be used herein.
The maximum nominal voltage difference between the components within the inner container 360 may be limited to few kilovolts only such that standard drive components may be used. Specifically, the electrical designs may be identical for all components, independent from the high voltage potential of the components against earth. High voltage may exist only between the surfaces of the inner container 360 and the outer container 370 that have a high voltage optimized design and, particularly, equal distances therebetween.
The modular stacked power converter vessels 350 thus provide optimized packaging and grounding systems and methods for marinized modular stacked HVDC systems. The modular stacked power converter vessels 350 achieve optimum power delivery with low system costs and complexity, high system reliability and maintainability, high efficiency, and high power density. The modular stacked power converter vessels 350 may operate with low or high power, over long or short distances, and for any type or number of loads.
It should be apparent that the foregoing relates only to certain embodiments of the present application and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.
