Patent Publication Number: US-2023163599-A1

Title: Offshore power transmission and distribution network

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application No. 63/281,457, filed Nov. 19, 2021, which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to systems and methods for offshore power transmission and distribution networks. 
     BACKGROUND 
     Although onshore power transmission is known, offshore power transmission poses different challenges due to the installation, operation, and efficiency in a subsea environment. 
     These and other deficiencies exist. 
     SUMMARY OF THE DISCLOSURE 
     Embodiments of the present disclosure provide a power distribution system. The power distribution system may include a plurality of generation nodes; a plurality of distribution nodes; and a plurality of load nodes. A first generation node may be configured to generate and transmit power to a first distribution node via a first transmission type, the first transmission type including medium voltage direct current (MVDC) or high voltage direct current (HVDC) or low frequency alternating current (LFAC). A second generation node may be configured to generate and transmit power to a second distribution node via a second transmission type, the second transmission type including high voltage alternating current (HVAC). The first distribution node may be configured to distribute the power to a first load node via the second transmission type, and distribute the power to a second load node via a third transmission type, the third transmission type including medium voltage alternating current (MVAC). The first load node may be configured to transmit the power to a first subsea facility via one or more flow lines and the third transmission type. The second load node may be configured to transmit the power to a second subsea facility via the one or more flow lines and the third transmission type. 
     Embodiments of the present disclosure provide a power distribution system. The power distribution system may include a plurality of generation nodes; a plurality of distribution nodes; and a plurality of load nodes. A first generation node may be configured to generate and transmit power to a first distribution node via a first transmission type, the first transmission type including MVDC or HVDC. A second generation node may be configured to generate and transmit power to a second distribution node via the first transmission type. The first distribution node may be configured to distribute the power to a first distribution load node via a second transmission type, the second transmission type include HVAC. The second distribution node may be configured to distribute the power to a second distribution load node via the second transmission type. The first distribution load node may be configured to transmit the power to a plurality of load nodes. The second distribution load note may be configured to transmit the power to a third load node. 
     Embodiments of the present disclosure provide a power distribution system. The power distribution system may include a plurality of generation nodes, distribution notes, and load nodes. A first generation node may be configured to generate and transmit power to a first distribution node via a first transmission type, the first transmission type including HVAC. A second generation node may be configured to generate and transmit power to the first distribution node via a second transmission type, the second transmission type including MVDC or HVDC. A third generation node may be configured to generate and transmit power to a second distribution node via the second transmission type. The first distribution node may be configured to distribute the power to a first load node. The second distribution node may be configured to distribute the power to two or more additional load nodes. 
     Embodiments of the present disclosure provide a power distribution system. The power distribution system may include a generation node a load node. The generation node may be configured to generate and transmit power to the load node by a first transmission type including HVAC via a subsea electrical distribution system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the present disclosure, together with further objects and advantages, may best be understood by reference to the following description taken in conjunction with the accompanying drawings. 
         FIG.  1    depicts an embodiment of a power distribution system according to an aspect of this disclosure. 
         FIG.  2    depicts a power distribution system according to an example embodiment. 
         FIG.  3    depicts a power distribution system according to an example embodiment. 
         FIG.  4    depicts a power distribution system according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following description of embodiments provides non-limiting representative examples referencing numerals to particularly describe features and teachings of different aspects of the invention. The embodiments described should be recognized as capable of implementation separately, or in combination, with other embodiments from the description of the embodiments. A person of ordinary skill in the art reviewing the description of embodiments should be able to learn and understand the different described aspects of the invention. The description of embodiments should facilitate understanding of the invention to such an extent that other implementations, not specifically covered but within the knowledge of a person of skill in the art having read the description of embodiments, would be understood to be consistent with an application of the invention. 
     The systems and methods disclosed herein transmit high power from onshore generation stations to deep water offshore facilities or between a plurality of deep water offshore facilities. Although subsea power transmission architecture has been studied to solve specific challenges, there is not a viable solution to distribute and transmit large quantities of power over long distances in deep water to a plurality of consumers. To address these and/or other challenges, the systems and methods disclosed herein include offshore power transmission and distribution networks to deliver electrical power to offshore consumers. Among other advantages, the disclosed embodiments may reduce a need for power generation on electrical topsides, allow longer subsea tiebacks to access stranded oil, and allow power to be shared between one or more assets. 
     The systems and methods disclosed herein may utilize a variety of types of nodes, which may generally refer to a variety of different types of facilities where electrical power may be generated, stored, transformed, distributed, or used to power a load. Without limitation, these nodes may include generation nodes, distribution nodes, load nodes, and/or any combination thereof, as explained below. 
     In some examples, one or more generation nodes may be configured to serve as a source of power for the transmission network. For example, the generation node may include an onshore power plant, jacket on the shelf with power, offshore gas turbine generators, a wind turbine, and so on. 
     In some examples, one or more distribution nodes may be configured to receive power from one or more generation nodes and distribute the power to one or more other distribution nodes and/or one or more load nodes. For example, the distribution node may include a substation, such as a transmission substation, a switching station, or a collector substation. In some examples, the distribution node may also serve as a load node. 
     In some examples, one or more load nodes may include or be associated with one or more consumers, such as a group of consumers, of electrical power. For example, the load node may comprise a motor or transformer, such as a stepdown transform, at an electrical distribution substation or subsea power grid. The load node may include, for instance, subsea equipment and/or equipment located on an offshore platform (e.g., topsides equipment). 
     In some examples, high voltage AC (HVAC) power transmission is utilized from a facility to a grid. In some examples, the facility may comprise a remote facility. In some examples, the grid may comprise a subsea power grid including one or more transformers, switchgear, and/or any combination thereof. The power may be routed to subsea electrical power consumers and/or an electrical topside. Although power may be transferred via HVAC, there is a point or threshold distance at which transfer of the power via AC is not feasible or not possible. At or before this point, in which the switch is made to HVDC, and all or nearly all of the diameter of the conductor is thus utilized. In this manner, bulk amounts of power may be transmitted for distribution at long distances. 
     In some examples, a combination of high voltage DC (HVDC) power transmission, HVAC, medium voltage (MVAC), and/or low frequency AC (LFAC) may be configured to transmit a large quantity of electrical power from a first facility to one or more second facilities. For example, the first facility may comprise a remote facility. In some examples, at least one of the second facilities may comprise an offshore electrical topside facility. In other examples, the one or more second facilities may comprise a plurality of offshore electrical topside facilities. Power may be inverted to MVAC for local or remote use, or HVAC where it may be supplied to an offshore electrical hub either subsea or topside where it may be stepped down in voltage and further distributed to consumers. 
     For the following systems, numerous power transmissions for various ranges of parameters for feeds may be used. For MVDC or HVDC, this may include 120 MW and extend about &lt;300 km and 250 MW and extend about 500 km-600 km, respectively. For LFAC, this may include about 50 MW and 300 km-600 km. For HVAC, this may include about 30 MW-80 MW and extend about &gt;200 km. For MVAC, this may include about 33 kV. In addition, various direct electrical heating cables (DEH) and flow lines may be utilized. 
     As noted, the present disclosure includes embodiments of offshore power transmission and distribution networks to deliver electrical power to offshore consumers. In one embodiment, an offshore power transmission and distribution network utilizes HVAC power transmission from a remote facility to a subsea power grid, which may include a subsea step-down transformer and subsea switchgear. The power can then be routed to subsea electrical power consumers and/or an electrical topside. In another embodiment, an offshore power transmission and distribution network utilizes a combination of HVDC power transmission from a remote facility or multiple facilities and HVAC, MVAC and/or LFAC to transmit a large quantity of electrical power to an offshore topside facility. Power is then inverted to MVAC for local or remote use or HVAC where it can then be supplied to offshore electrical hub either subsea or topside where it can be stepped down in voltage and further distributed to consumers. Examples of such embodiments are described in further detail herein. 
       FIG.  1    illustrates a power distribution system according to an example embodiment in which HVAC is used for initial transmission from an onshore power generation facility. The first system may comprise a first network. The first network may include a radial network  100 . For example, the radial network may include a generation node  110 , a distribution system  120 , and a load node  130 . It is understood that although single instances of components of network  100  may be depicted, network  100  may include any number of components. 
     The generation node  110  may include a power source generation node, including but not limited to renewables or a power plant. The power source generation node may be located onshore. In addition, the radial network may include a cable  105  (a feed  105 ), such as an HVAC cable that may terminate at a transformer. The power may be transmitted from the generation node  110  to the distribution system  120 , such as a subsea electrical distribution system and supply power to various features, such as a topside of an offshore platform. In some examples, the distribution system  120  may include any number of transformers, boosting pumps, and/or compressors. In addition, the radial network  100  may utilize one or more feed lines between the generation node  110  and the load node  130 . The feed  105  from the generation node  110  to the subsea electrical distribution system  120  may be via HVAC to distribute the power to the load node  130 . Various flow lines  115  and DEH cables  125  and MVAC  135  may be used to tie the distribution system  120  and load node  130 . In an embodiment, the subsea electrical distribution system  120  may include one or more transformers to step the voltage down from high voltage to medium voltage for use by the subsea equipment and the illustrated platform. 
       FIG.  2    illustrates a power distribution system according to an example embodiment. The second system may comprise a second network. The second network may include a bulk power radial hub network  200 . For example, the bulk power radial hub network  200  may include one or more generation nodes, distribution nodes, and load nodes. It is understood that although single instances of components of network  200  may be depicted, network  200  may include any number of components and include or reference any component of network  100  of  FIG.  1   . 
     As illustrated in  FIG.  2   , a first generation node  210  may comprise an onshore power generation node. A second generation node  220  may be configured to provide supplemental power from an additional source, for instance offshore power generation features which may include but are not limited to a wind turbine. In some examples, the wind turbine may be part of a wind farm. Without limitation, the feed  205  from the first generation node  210  to the distribution node  230  may be via DC, HVAC, or LFAC. Without limitation, the feed  215  from the second generation node  220  to the distribution node  230  may be via HVAC. Power may be distributed to a subsea system from the distribution node  230 . The distribution node  230  may distribute the power to various load nodes  240 ,  250  via feeds. For example, the distribution node  230  may distribute power to a first load node  240  via HVAC  215 . The distribution node  230  may also distribute power to a second load node  250  via MVAC  235 . In some examples, the load nodes may be tied to respective subsea systems for power supply thereto. For example, the first load node  240  may be tied to a first subsea system  245  via flow line  225 , and the second load node  250  may be tied to a second subsea system  255  via flow line  225 . The distribution node  230  may also distribute power to a third load node  260  via HVAC  215 . In addition, an existing platform  270  with limited spinning reserve may be configured to receive the distributed power through the third load node via MVAC. That is, one of the load nodes  260  may be tied to the existing platform  270  via MVAC  235 . In addition, various flow lines  225  and DEH cables  265  may be used. 
       FIG.  3    illustrates a power distribution system according to an example embodiment. The third system may comprise a third network. The third network may include a bulk power ring network  300 . For example, the bulk power ring network  300  may include one or more generation nodes, distribution nodes, and load nodes. It is understood that although single instances of components of network  300  may be depicted, network  300  may include any number of components and include or reference any component of network  100  of  FIG.  1   , and network  200  of  FIG.  2   . 
     In some embodiments, the system may include multiple generation nodes  310 ,  320  located onshore. The onshore generation nodes  310 ,  320  may have similar configurations or different configurations (e.g., the same fuel sources or different fuel sources). The feed  305  for power from the first generation node  310  to a first distribution node  330  may be via MVDC or HVDC. The first distribution node  330  may comprise an unmanned platform or facility configured to distribute and deliver power to other nodes. The feed  305  from the second generation node  320  to a second distribution node  340  may be MVDC or HVDC. Feed  305  may be used to tie first distribution node  330  to second distribution node  340  (e.g., an offshore transport). For example, each of the first and second distribution nodes  330 ,  340  may be tied to each other via MVDC or HVDC  305 , and also tied to distribution and load nodes  350 ,  360 . For example, the first distribution node  330  may feed power to a first distribution and load node  350  via HVAC  315 . The second distribution node  340  may feed power to a second distribution and load node  360  via HVAC  315 . Each of the distribution and load nodes  350 ,  360  may be configured to distribute power to various load nodes  370 ,  380 ,  390 . For example, the first distribution and load node  350  may distribute power to a first load node  370  and a second load node  380  via MVAC  325 . The second distribution and load node  360  may be tied to the third load node  370  via various feeds. In addition, various flow lines  335  and DEH cables  345  may be used. 
       FIG.  4    illustrates a power distribution system according to an example embodiment. This system may comprise a network  400 . The network  400  may include one or more generation nodes, distribution nodes, and load nodes. It is understood that although single instances of components of network  400  may be depicted, network  400  may include any number of components and include or reference any component of network  100  of  FIG.  1   , network  200  of  FIG.  2   , and network  300  of  FIG.  3   . 
     For example, a first generation node  410  may comprise one or more turbines. The first generation node  410  and a second generation node  420  may be tied to a first distribution node  440 . For example, the first generation node  410  may be tied to the first distribution node  440  via HVAC feed  405 . The second generation node  420  may be tied to the first distribution node  440  via MVDC or HVDC feed  415 . The third generation node  430  may be tied to a second distribution node  450  via MVDC or HVDC  415 . The first and second distribution nodes  440 ,  450  may be tied via MVDC or HVDC  415 . The first distribution node  440  may be configured to distribute power to a first load node  460  via HVAC  405 . The second distribution node  450  may be configured to distribute power to a second load node  470  via HVAC  405 . In this manner, the flexibility of the power generation and distribution of the network  400  is shown, and as such is not limited to power from a source on shore such as the beach but rather may be derived from an existing refinery or similar asset located on shore. In addition, renewable may derive power from any number of sources, including but not limited to wind, solar, etc. 
     For any of the above systems, a plurality of categories of components may be utilized, in any number and in any combination. For example, the plurality of categories of components may include cable, topside equipment, and subsea equipment. The cables may include static and dynamic cables, and/or any combination thereof. The topside equipment may include a transformer, a frequency converter, a shunt reactor, and/or any combination thereof. The subsea equipment may include a transformer, a frequency converter, a shunt reactor, an adjustable speed drive, a wet mate connector, and/or any combination thereof. For MVAC operation, such as &lt;69 kV, the depth of operation subsea for each of the static and dynamic cables may extend to at least 3000 m, topside equipment may include any combination of a transformer, a frequency converter, a shunt reactor, and the subsea equipment may include a transformer, ASD, and a wet mate connector. For HVAC operation, such as &gt;69 kV, the depth of operation subsea for the static cable may extend to at least 3000 m, topside equipment may include any combination of a transformer, a frequency converter, a shunt reactor, and subsea equipment may include a transformer. For LFAC operation, the depth of operation subsea for the static cable may extend to at least 3000 m, topside equipment may include any combination of a transformer, a frequency converter, a shunt reactor, and the subsea equipment may include a ASD configured to operated at a low frequency. For HVDC operation, the topside equipment may include a transformer and a shunt reactor. 
     In the preceding specification, various embodiments have been described with references to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded as an illustrative rather than restrictive sense.