Floating substation and distribution method for managing electrical power generated by an offshore power production plant

Abstract

A floating substation for managing electrical power generated by an offshore wind power production plant has a floating platform (11) comprising a hull (12) configured to receive a hydrostatic force from the bottom upwards, and an open-air main deck (13), which is directly supported by the hull (12); and an electrical power management unit (14), which is arranged on the main deck (13) and is configured to receive electrical power from the wind power production plant (2) via at least one electric inlet cable (5), to transform the voltage of the received electrical power, and to supply the transformed electrical power to a remote station (7) via at least one electric outlet cable (6).

Description

[0001] "FLOATING SUBSTATION AND DISTRIBUTION METHOD FOR MANAGING ELECTRICAL POWER GENERATED BY AN OFFSHORE POWER PRODUCTION PLANT"

[0002] Cross-Reference to Related Applications

[0003] This Patent Application claims priority from Italian Patent Application No . 102022000026817 filed on December 23 , 2022 , the entire disclosure of which is incorporated herein by reference .

[0004] Technical Field

[0005] The present invention relates to a floating substation and a distribution method for managing electrical power generated by an of fshore power production plant .

[0006] Moreover, the present invention relates to an electrical power production and distribution system comprising said floating substation .

[0007] State of the Art

[0008] As is known, considerable technological advances have been made in the last decades with regard to electric generators that exploit renewable energy sources at an of fshore site . In particular, these technological advances have led to the manufacturing of wind turbine generators with rated powers of tens of MW connected to each other to form of fshore wind farms in a body of water, characteri zed by increasing dimensions , higher powers , and long distances from the mainland .

[0009] A consequence of such technological advances is the increase in the total rated power of each wind farm, which can exceed 100 MW, and thus in the number of interconnecting cables , commonly called "array cables" , each of which connects a group of wind turbine generators to each other converging towards a distribution substation, and the number of which can exceed ten cables . Therefore , in order to make the transport of high powers more cost-ef fective , it is necessary to increase the voltage of the electrical power and possibly convert the electric signal from alternating current to direct current or vice versa .

[0010] Said distribution substation is electrically connected to a remote station, typically placed on the mainland, via additional electric cables , known as "export cables" , to trans fer the power to an electric grid on the mainland .

[0011] Said distribution substation generally comprises heavy electrical components , such as alternating-current and high- voltage trans formers which trans form the voltage value from 66 kV to 230 kV . Moreover, the distribution substation comprises additional heavy electrical components , such as for example switching reactors which stabili ze the electrical signal .

[0012] In addition to said heavy electrical components , the distribution substation typically comprises additional , lighter electrical components that are sensitive to accelerations , such as for example insulated disconnectors enclosed in a casing insulated from the external environment via pressuri zed gas , which are commonly called "Gas- Insulated Switchgears ( GISs ) " . In particular, both GISs that operate with alternating current and GISs that operate with direct current are known .

[0013] Typically, the distribution substation can operate with HVAC (High Voltage Alternate Current ) or, alternatively, with HVDC (High Voltage Direct Current ) . Regardless of the characteristics o f the managed electric current , alternating current or direct current , the electrical components of the distribution substation have a considerable weight .

[0014] In the case where the body of water has a limited depth, in order to support the distribution substation above the surface of the body of water, it is known to utili ze fixed foundations comprising plinths piled to the bed of the body of water, commonly called "j ackets" .

[0015] However, such constructive solution can be excessively heavy, complex and risky to make since the bed of the body of water can be uneven and inhomogeneous . Moreover, said constructive solution becomes economically unsustainable in the case where the body of water has a great depth .

[0016] In the oil & gas industry, numerous types of floating platforms that accommodate hydrocarbon extraction and processing plants are known, such as for example semisubmersibles , tension-leg platforms ( TLPs ) , tubular platforms ( spar buoys ) , or ships . Such types of floating platforms have in common the fact of compris ing modules with a vertical development , which support the hydrocarbon extraction and processing plants and consist of columns and levels . Therefore , the center of gravity of said floating platforms is located at a high height , at a great distance from the surface of the body of water and, as a consequence , the stability of the floating platform is limited .

[0017] Nevertheless , for depths of the body of water greater than about 60 meters , it is generally advantageous to set up a floating distribution substation moored on the bed of the body of water .

[0018] Since it floats , the distribution substation is subj ect to shi fts and accelerations due to the wave motion or to currents of the body of water . By way of example , the floating distribution substation is subj ect to rolling, pitching and j olting shi fts and accelerations .

[0019] Such dynamic behavior induced by the environmental forces (waves , wind, currents , etc . ) on the distribution substation causes both the electrical components of the distribution substation and the array cables as well as the export cables to undergo stresses that can damage them . In particular, array and export cables typically have an operational li fe of over 20 years and, as a consequence , since they are subj ect to cyclic stresses due to the dynamic behavior of the distribution substation, the risk that fatigue damage may occur is high . Similarly, the main electrical components of the substation consist of delicate elements that poorly withstand high dynamic stresses .

[0020] Subject-Matter of the Patent

[0021] An obj ect of the present invention is to provide a floating substation for managing electrical power generated by an of fshore power production plant which mitigates the drawbacks of the prior art . In particular, an obj ect of the present invention is to mitigate the drawbacks connected to the use of fixed foundations and to improve the stability and the dynamic behavior of the floating substation . Moreover, it is an obj ect of the present invention to increase the simplicity of installation of the electric cables .

[0022] In accordance with the present invention, a floating substation for managing electrical power generated by an of fshore wind power production plant is provided, the floating substation comprising :

[0023] - a floating platform comprising a hull configured to receive a hydrostatic force from the bottom upwards when at least partially immersed in a body of water, and an open-air main deck, which is directly supported by the hull ; and

[0024] - an electrical power management unit , which is arranged on the main deck and is configured to receive electrical power from the wind power production plant via at least one electric inlet cable , to trans form the voltage of the received electrical power, and to supply the trans formed electrical power to a remote station via at least one electric outlet cable .

[0025] Thanks to the present invention, it is possible to lower the center of gravity of the floating substation, so as to limit the shi fts and the accelerations of the floating substation due to the movements of the body of water . In this manner, it is possible to reduce the risk of damaging the electrical power management unit and the electric inlet and outlet cables .

[0026] In other words , the floating platform comprises one single open-air main deck, directly supported by the hull and without any covering, entailing a saving also in terms of weight . In actual fact , the floating platform comprises a single-level structure that develops hori zontally, from one side of the hull to the other both longitudinally and transversely . In this manner, it is possible to keep the center of gravity of the floating substation low since all the heavier electrical components are arranged on the main deck .

[0027] The main deck is thus the structure supporting the heavy electrical components and the equipment for pulling and connecting the array cables and the export cables .

[0028] A further obj ect of the present invention is to provide a distribution method for managing electrical power generated by an of fshore power production plant which mitigates the drawbacks of the prior art set out herein .

[0029] In accordance with the present invention, a distribution method for managing electrical power generated by an of fshore wind power production plant is provided, the distribution method comprising the steps of :

[0030] - arranging an electrical power management unit on an open-air main deck of a floating platform placed in a body of water ;

[0031] - transmitting electrical power from the wind power production plant to the electrical power management unit ; trans forming the voltage of the transmitted electrical power via the electrical power management unit ; and

[0032] - supplying the trans formed electrical power from the electrical power management unit to a remote station .

[0033] Thanks to the present method, it is possible to distribute electrical power from a production plant to a remote substation in a safe and reliable manner .

[0034] In particular, thanks to the fact that the electrical power management unit is arranged on a floating platform having an open-air main deck, it is possible to lower the center of gravity of the floating platform, in this manner limiting the shi fts and the accelerations of the electrical power management unit in the body of water .

[0035] Brief Description of the Figures

[0036] Further characteristics and advantages of the present invention will become apparent from the appended dependent claims and from the following description of a non-limiting example embodiment , with reference to the accompanying figures , wherein :

[0037] - Figure 1 is a schematic view of an electrical power production and distribution system manufactured in accordance with the present invention;

[0038] - Figure 2 is a perspective view, with parts removed for clarity and parts schemati zed, of a floating substation of the system of Figure 1 ;

[0039] - Figure 3 is a side elevation view, with parts removed for clarity and parts schemati zed, of the floating substation of Figure 2 ; and

[0040] - Figure 4 is a section view, with parts removed for clarity and parts schemati zed, of the floating substation of Figure 2 .

[0041] Detailed Description of the Figures

[0042] With reference to Figure 1 , reference numeral 1 indicates , as a whole , an electrical power production and distribution system for producing and distributing electrical power from a renewable energy source to a remote distribution network . The production and distribution system 1 comprises an of fshore wind power production plant 2 , which is arranged in a body of water 3 and is configured to generate electricity; a floating substation 4 for managing the electrical power generated by the wind power production plant 2 ; an electric inlet cable 5 , which electrically connects the wind power production plant 2 to the floating substation 4 to transmit electrical power from the wind power production plant 2 to the floating substation 4 ; and an electric outlet cable 6 , which electrically connects the floating substation 4 to a remote station 7 to transmit electrical power from the floating substation 4 to the remote station 7 .

[0043] The substation 4 floats in the body of water 3 and, in particular, is moored at the wind power production plant 2 .

[0044] In the particular non-limiting case of the present invention described and illustrated herein, the wind power production plant 2 comprises a plurality of wind turbine generators 8 connected to each other in series via the inlet cable 5 . In particular, each wind turbine generator 8 comprises a respective foundation 9 floating in the body of water 3 .

[0045] The electric inlet cable 5 is commonly called "array cable" and the electric output cable 6 is commonly called "export cable" .

[0046] In particular, the production and distribution system 1 comprises a plurality of electric inlet cables 5 and a plurality of electric output cables 6 .

[0047] More speci fically, the electric inlet cables 5 and the electric outlet cables 6 are configured to transmit high- voltage power and preferably comprise copper conductors wrapped in a series of shielding layers .

[0048] In accordance with an embodiment , the production and distribution system 1 comprises a plurality of electric inlet cables 5 , each of which connects in series a respective group of wind turbine generators 8 to the floating substation 4 . Moreover, the production and distribution system 1 comprises a plurality of electric outlet cables 6 , each of which connects the floating substation 4 to the remote station 7 .

[0049] In particular, each electric inlet cable 5 extends between various consecutive wind turbine generators 8 ( two in the case shown in Figure 1 ) and between a wind turbine generator 8 and the floating substation 4 , resting for a respective section on the bed of the body of water 3 i f allowed by the non-exceedingly great depths . Moreover, each electric outlet cable 6 extends between the floating substation 4 and the remote station 7 resting for a respective section on the bed of the body of water 3 .

[0050] In the particular case described and illustrated herein, the remote station 7 is placed on the mainland at a great distance from the floating substation 4 . In particular, the remote station 7 is connected to an electric grid 10 and is configured to trans form the voltage of the electrical power transmitted by the floating substation 4 to a voltage value suitable for supplying the electrical power into the electric grid 10 . More speci fically, the remote station 7 is configured to adj ust the voltage of the electrical power transmitted by the floating substation 4 to the voltage of the electric grid 10 .

[0051] With reference to Figure 2 , the floating substation 4 comprises a floating platform 11 comprising a hull 12 configured to receive a hydrostatic force from the bottom upwards when at least partially immersed in the body of water 3 , and an open-air main deck 13 , which is directly supported by the hull 12 ; and an electrical power management unit 14 , which is arranged on the main deck 13 and is configured to receive electrical power from the wind power production plant 2 via the electric inlet cable 5 ( Figures 1 , 3 and 4 ) , to trans form the voltage of the received electrical power, and to supply the trans formed electrical power to a remote station 7 ( Figure 1 ) via the electric outlet cable 6 ( Figures 1 , 3 and 4 ) .

[0052] In particular, the floating platform 11 comprises one single main deck 13 directly supported by the hull 12 and without any covering . In other words , the floating platform 11 comprises a single-level structure that develops hori zontally from one side to the other, both longitudinally and transversely .

[0053] More speci fically, the main deck 13 has a substantially quadrilateral shape in plan, preferably a substantially square shape .

[0054] In the particular non-limiting case of the present invention described and illustrated herein, the hull 12 comprises a base 15 , which is arranged at a distance from the main deck 13 , and a plurality of columns 16 , which connect the base 15 to the main deck 13 .

[0055] In particular, each column 16 extends transversely with respect to the main deck 13 and the base 15 . In practice , the columns 16 have the function o f supporting and allowing the floating of the main deck 13 on the surface of the body of water 3 .

[0056] More speci fically, the hull 12 comprises four columns

[0057] 16 , each of which is arranged at a corner of the substantially quadrilateral shape of the main deck 13 . In practice , the hull 12 is provided with four through openings

[0058] 17 , each of which is delimited by two adj acent columns 16 , by the base 15 and by the main deck 13 .

[0059] In accordance with an embodiment, the base 15 is flat and extends along a plane substantially parallel to the main deck 13 .

[0060] In particular, the base 15 has a substantially quadrangular frame shape in plan . More speci fically, the base 15 comprises four elongated elements 18 ( commonly called "pontoons" ) , each of which extends transversely with respect to the columns 16 and connects two adj acent columns 16 to each other . In practice , the base 15 is provided with a central through opening 19 delimited by the elongated elements 18 .

[0061] In particular, the base 15 and the columns 16 are divided into watertight compartments via a plurality of bulkheads , not shown in the accompanying figures , so as to ensure the floating of the floating platform 11 also in the case of flooding of a given number of watertight compartments . Moreover, each column 16 is configured to accommodate at least one tank, not shown in the accompanying figures , for holding service liquids , such as water or oily liquids . In this manner, it is possible to further lower the center of gravity of the floating platform 11 , positioning said tank below the main deck 13 .

[0062] In accordance with a non-limiting embodiment of the present invention, the electrical power management unit 14 is configured to trans form the voltage of the electrical power generated by the wind power production plant 2 from about 66 kV to about 230 kV .

[0063] In particular, the electrical power management unit 14 comprises an electrical panel 20 , which is configured to selectively electrically connect / disconnect the electrical power management unit 14 to / from the electric inlet cable 5 ( Figures 1 , 3 and 4 ) ; and an electrical panel 21 , which is configured to selectively electrically connect / disconnect the electrical power management unit 14 to / from the electric outlet cable 6 .

[0064] More speci fically, each of the electrical panels 20 and 21 comprises a switching device , not shown in the accompanying figures , which is insulated in a pressuri zed gas , such as for example sul fur hexafluoride ( S Fs) . More speci fically, said switching device is commonly called "Gas- Insulated Switchgear ( GIS ) " .

[0065] In the particular non-limiting case of the present invention described and illustrated herein, the floating platform 11 comprises an upper mezzanine 27 , which is raised with respect to the main deck 13 and supports the electrical panel 20 ; and an upper mez zanine 28 , which is raised with respect to the main deck 13 and supports the electrical panel 21 .

[0066] In particular, the upper mez zanines 27 and 28 are arranged on the main deck 13 according to an arrangement that minimi zes the dynamic ef fects due to the environmental forces and enables the rapid installation of the electric inlet cables 5 and electric outlet cables 6 .

[0067] More speci fically, the surface in plan of each mez zanine 27 , 28 is smaller than the surface in plan of the main deck 13 . In the particular non-limiting case of the present invention described and illustrated herein, the extension in plan of each mezzanine 27 , 28 is smaller than a quarter of the extension in plan of the main deck 13 .

[0068] In accordance with an embodiment , the electrical power management unit 14 comprises at least one electrical trans former 22 , which is configured to trans form the voltage of the electrical power received from the wind power production plant 2 from an input value to an output value greater than the input value .

[0069] In particular, the electrical trans former 22 is configured to transform the voltage of the electrical power received from the wind power production plant 2 from 66 kV to 230 kV .

[0070] More speci fically, the electrical power management unit 14 comprises two electrical trans formers 22 , each of which is directly placed on the main deck 13 .

[0071] Moreover, the electrical power management unit 14 comprises at least one voltage stabili zer 23 configured to keep the voltage of the received electrical power within a defined voltage band also when voltage fluctuations occur, allowing adapting the voltage of the electrical power to the requirements of the production and distribution system 1 and simultaneously reducing the losses .

[0072] In particular, the electrical power management unit 14 comprises two voltage stabili zers 23 , each of which is directly placed on the main deck 13 .

[0073] With reference to Figure 3 , the electrical connections between the electrical components of the electrical power management unit 14 are shown .

[0074] In particular, the electrical power management unit 14 comprises an electric cable 24 , which electrically connects the electrical panel 20 to the electrical trans former 22 ; an electric cable 25 , which electrically connects the electrical trans former 22 to the electrical panel 21 ; and an electric cable 26 which electrically connects the electrical panel 21 to the voltage stabili zer 23 .

[0075] The electric inlet cable 5 electrically connects the wind power production plant 2 ( Figure 1 ) to the electrical panel 20 and the outlet cable 6 electrically connects the electrical panel 21 to the remote station 7 ( Figure 1 ) .

[0076] With reference to Figure 4 , the base 15 is shaped so as to allow the passage of the electric inlet cables 5 and the electric outlet cables 6 through the central through opening 19 .

[0077] In particular, the electric inlet cables 5 are coupled to a first elongated element 18 and the electric outlet cables 6 are coupled to a second elongated element 18 opposite the first elongated element 18 .

[0078] In use and with reference to Figure 1 , the wind turbine generators 8 of the wind power production plant 2 generate electrical power, which is transmitted to the floating substation 4 via the electric inlet cable 5 .

[0079] With reference to Figure 3 , the inlet cable 5 transmits the electrical power generated by the wind power production plant 2 to the electrical panel 20 . The electric cable 24 transmits the electrical power from the electrical panel 20 to the electrical trans former 22 , which trans forms the voltage of the received electrical power from an input value to an output value greater than the input value . In particular, the electrical trans former 22 trans forms the voltage of the received electrical power from about 66 kV to about 230 kV .

[0080] The trans formed electrical power is transmitted from the electrical trans former 22 to the electrical panel 21 via the electric cable 25 . Possible fluctuations in the voltage of the electrical power are stabili zed via the voltage stabili zer 23 , which is connected to the electrical panel 21 via the electric cable 26 .

[0081] At this point , the trans formed power is supplied from the electrical panel 21 to the remote station 7 via the electric outlet cable 6 .

[0082] It is finally evident that variations can be made to the present invention with respect to the described embodiment without departing from the scope of protection of the appended claims .

Claims

CLAIMS1. A floating substation for managing electrical power generated by an offshore wind power production plant, the floating substation (4) comprising: a floating platform (11) comprising a hull (12) configured to receive a hydrostatic force from the bottom upwards when at least partially immersed in a body of water (3) , and an open-air main deck (13) , which is directly supported by the hull (12) ; and- an electrical power management unit (14) , which is arranged on the main deck (13) and is configured to receive electrical power from the wind power production plant (2) via at least one electric inlet cable (5) , to transform the voltage of the received electrical power, and to supply the transformed electrical power to a remote station (7) via at least one electric outlet cable (6) .

2. The floating substation as claimed in Claim 1, wherein the electrical power management unit (14) comprises at least one first electrical panel (20) , which is configured to selectively electrically connect / disconnect the electrical power management unit (14) to / from the at least one electric inlet cable (5) .

3. The floating substation as claimed in Claim 1 or 2, wherein the electrical power management unit (14) comprises at least one second electrical panel (21) , which is configured to selectively electrically connect / disconnect the electrical power management unit (14) to / from the at least one electric outlet cable (6) .

4. The floating substation as claimed in any one of the foregoing Claims, wherein the electrical power management unit (14) comprises at least one electrical transformer (22) , which is configured to transform the voltage of the electrical power received from the wind power production plant (2) from an input value to an output value greater than the input value.

5. The floating substation as claimed in any one of the foregoing Claims, wherein the main deck (13) has a substantially quadrilateral shape in plan, preferably a substantially square shape.

6. The floating substation as claimed in Claim 5, wherein the hull (12) comprises a base (15) , which is placed at a distance from the main deck (13) , and a plurality of columns (16) , which connect the base (15) to the main deck (13) .

7. The floating substation as claimed in Claim 6, wherein the hull (12) comprises four columns (16) , each of which is arranged at a corner of the substantially quadrilateral shape of the main deck (13) .

8. The floating substation as claimed in Claim 6 or 7, wherein the base (15) is provided with a central through opening (19) , preferably so as to allow the passage of the at least one electric inlet cable (5) and the at least one electric outlet cable (6) through the central through opening (19) .

9. The floating substation as claimed in Claim 8, wherein the base (15) has a substantially quadrangular frame shape in plan.

10. An electrical power production and distribution system comprising:- an offshore wind power production plant (2) , which is arranged in a body of water (3) and is configured to generate electricity, preferably the wind power production plant (2) comprising at least one wind turbine generator (8) ;- a floating substation (4) as claimed in any one of the foregoing Claims; at least one electric inlet cable (5) , which electrically connects the wind power production plant (2) to the floating substation (4) for transmitting electrical power from the wind power production plant (2) to the floating substation (4) ; andat least one electric outlet cable (6) , which electrically connects the floating substation (4) to a remote station (7) for transmitting electrical power from the floating substation (4) to the remote station (7) .

11. A distribution method for managing electrical power generated by an offshore wind power production plant, the distribution method comprising the steps of:- arranging an electrical power management unit (14) on an open-air main deck (13) of a floating platform (11) placed in a body of water (3) ;- transmitting electrical power from the wind power production plant (2) to the electrical power management unit (14) ; transforming the voltage of the transmitted electrical power by means of the electrical power management unit ( 14 ) ; and- supplying the transformed electrical power from the electrical power management unit (14) to a remote station (7) .

12. The distribution method as claimed in Claim 11, and comprising the step of selectively electrically connecting / disconnecting the electrical power management unit (14) to / from the wind power production plant (2) via a first electrical panel (20) of the electrical power management unit (14) .

13. The distribution method as claimed in Claim 11 or 12, and comprising the step of selectively electrically connecting / disconnecting the electrical power management unit (14) to / from the remote station (7) via a second electrical panel (21) of the electrical power management unit (14) .

14. The distribution method as claimed in any one of Claims 11 to 13, wherein the voltage of the electrical power transmitted from the wind power production plant (2) to the electrical power management unit (14) is transformed from an input value to an output value greater than the input value.

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