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

Abstract

A floating substation for managing power generated by an offshore wind power plant includes a floating platform (11) having a float (12) configured to receive upward hydrostatic pressure from the bottom and an open main deck (13) directly supported by the float (12), and a power management unit (14) arranged on the main deck (13) and configured to receive power from the wind power plant (2) via at least one electrical input cable (5), convert the voltage of the received power, and supply the converted power to a remote station (7) via at least one electrical output cable (6).

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to Italian Patent Application No. 102022000026817, filed December 23, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a floating substation and distribution method for managing electrical power generated by an offshore power plant.

[0003] The present invention also relates to an electric power production and distribution system comprising the floating substation. [Background technology]

[0004] The past decade has seen significant technological advances in offshore renewable energy generators, leading to the production of large-scale, high-power, tens-of-megawatt wind turbine generators that can be interconnected to form offshore wind farms in the ocean, and are located at long distances from land.

[0005] The result of these technological advances is an increase in the total rated power output of each wind farm, which can exceed 100 MW, and hence the number of interconnecting cables, commonly called "array cables", which connect groups of wind turbine generators together and to distribution substations, which can number more than 10. Therefore, to transport higher power more cost-effectively, it is necessary to increase the voltage of the electricity and, where possible, convert the electrical signal from AC to DC and vice versa.

[0006] The distribution substations are electrically connected to remote stations, typically located on land, via additional electrical cables known as "export cables," which transport the power to the land-based power grid.

[0007] The distribution substation typically includes large electrical components such as AC high voltage converters that convert voltage levels from 66 kV to 230 kV, and additional large electrical components such as switching reactors to stabilize the electrical signals.

[0008] In addition to the large electrical components, distribution subsystems typically include additional lightweight electrical components that are sensitive to acceleration, such as insulating disconnectors that are enclosed in enclosures that are insulated from the outside environment via pressurized gas and are commonly referred to as "gas insulated switchgear (GIS)." In particular, both AC-operated and DC-operated GIS are known.

[0009] Typically, distribution substations may operate on HVAC (High Voltage Alternating Current) or alternatively on HVDC (High Voltage Direct Current). Regardless of the nature of the current being managed, i.e., AC or DC, the electrical components of a distribution substation have a significant weight.

[0010] In cases where the depth of the seawater is limited, it is known to utilize a fixed foundation comprising foundation stones, commonly referred to as a "jacket", stacked on the bottom of the seawater to support the distribution substation above the surface of the seawater.

[0011] However, because the seabed can be uneven and uneven, such engineering solutions can be excessively heavy, complex and dangerous to construct, and in cases where the seabed is very deep, the engineering solutions become economically unsustainable.

[0012] In the oil and gas industry, many types of floating platforms are known that house hydrocarbon extraction and processing plants, such as semi-submersible offshore drilling rigs, tension-moored platforms (TLPs), tubular platforms (spar buoys), or ships. These types of floating platforms have in common the fact that they support the hydrocarbon extraction and processing plant and comprise a vertically deployable module consisting of a spar and a horizontal surface. Therefore, the center of gravity of the floating platform is located at a considerable height, at a considerable distance from the surface of the seawater, which results in limited stability of the floating platform.

[0013] Nevertheless, for seawater depths greater than about 60 meters, it is generally advantageous to construct floating distribution substations moored to the seawater bottom.

[0014] Being floating, the distribution substation is subject to displacements and accelerations due to wave action or currents in the ocean. For example, floating distribution substations are subject to displacements and accelerations due to rolling, pitching, and shocks.

[0015] This dynamic behavior induced in the distribution substation by environmental forces (waves, wind, currents, etc.) places stresses on both the distribution substation's electrical components and the array cables as well as the export cables that can damage them. Specifically, the array and export cables typically have operational lives in excess of 20 years, and as a result, are at high risk of fatigue damage due to the cyclic stresses caused by the dynamic behavior of the distribution substation. Similarly, the substation's main electrical components are made of precision components with low resistance to high dynamic stresses. Summary of the Invention [Problem to be solved by the invention]

[0016] The object of the present invention is to provide a floating substation for managing the power generated by an offshore power plant, which overcomes the drawbacks of the prior art. More specifically, the object of the present invention is to overcome the drawbacks associated with the use of fixed foundations and to improve the stability and dynamic behavior of the floating substation. It is also an object of the present invention to increase the ease of laying electrical cables. [Means for solving the problem]

[0017] According to the present invention, there is provided a floating substation for managing power generated by an offshore wind power plant, the floating substation comprising: a floating platform comprising a floating body configured to receive an upward hydrostatic pressure force from the bottom when at least partially submerged in seawater, and an open main deck directly supported by the floating body; a power management unit arranged on the main deck and configured to receive power from the wind power plant via at least one electrical lead-in cable, convert a voltage of the received power, and supply the converted power to a remote station via at least one electrical lead-out cable; It is equipped with:

[0018] The present invention allows the center of gravity of the floating substation to be lowered to limit displacement and acceleration of the floating substation due to seawater movement, thus reducing the risk of damage to the power management unit and electrical lead-in and lead-out cables.

[0019] In other words, the floating platform has a single open main deck that is supported directly on the floating body and does not have any covering, which entails savings in weight. In fact, the floating platform has a single level structure that extends horizontally from one side of the floating body to the other in both the longitudinal and lateral directions. In this way, it is possible to keep the center of gravity of the floating substation low, since all of the relatively heavy electrical components are located on the main deck.

[0020] The main deck is therefore the structure that supports the heavy electrical components and the facilities for tensioning and connecting the array and export cables.

[0021] It is a further object of the present invention to provide a distribution method for managing electrical power generated by an offshore power plant that overcomes the drawbacks of the prior art described herein.

[0022] According to the present invention, there is provided a distribution method for managing power generated by an offshore wind power plant, the distribution method comprising: - disposing a power management unit on an open main deck of a floating platform installed in seawater; - transmitting power from the wind power plant to a power management unit; - converting the voltage of the transmitted power via a power management unit; - supplying the converted power from the power management unit to the remote station; Includes.

[0023] In this way, it is possible to distribute power from a power plant to remote substations in a safe and secure manner.

[0024] In particular, the fact that the power management unit is located on a floating platform with an open main deck makes it possible to lower the center of gravity of the floating platform and thus limit the displacement and acceleration of the power management unit in seawater.

[0025] Further features and advantages of the invention will become apparent from the appended dependent claims and from the following description of non-limiting example embodiments, with reference to the accompanying drawings. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic diagram of an electrical power production and distribution system constructed in accordance with the present invention; [Figure 2] 2 is a partially schematic, partially broken away perspective view of a floating substation of the system of FIG. 1; [Figure 3] FIG. 3 is a partially schematic side view, with parts removed for clarity, of the floating substation of FIG. 2; [Figure 4] 3 is a partially schematic cross-sectional view of the floating substation of FIG. 2, with parts removed for clarity; DETAILED DESCRIPTION OF THE INVENTION

[0027] Referring to Figure 1, reference numeral 1 generally designates an electricity production and distribution system for producing and distributing electricity from renewable energy sources to a remote electricity grid. The production and distribution system 1 includes an offshore wind power plant 2 disposed in seawater 3 and configured to generate electricity, a floating substation 4 for managing the electricity generated by the wind power plant 2, an electrical inflow cable 5 electrically connecting the wind power plant 2 to the floating substation 4 and transmitting the electricity from the wind power plant 2 to the floating substation 4, and an electrical outflow cable 6 electrically connecting the floating substation 4 to a remote station 7 and transmitting the electricity from the floating substation 4 to the remote station 7.

[0028] The substation 4 is floating in seawater 3 and is specifically moored to the wind power plant 2.

[0029] In the particular, non-limiting case of the invention described and illustrated herein, the wind power plant 2 comprises a plurality of wind turbine generators 8 connected in series with one another via lead-in cables 5. In particular, each wind turbine generator 8 comprises a respective foundation 9 floating in seawater 3.

[0030] The electrical input cable 5 is commonly called an "array cable," and the electrical output cable 6 is commonly called an "export cable."

[0031] More specifically, the production distribution system 1 includes a plurality of electrical lead-in cables 5 and a plurality of electrical lead-out cables 6 .

[0032] More specifically, electrical inlet cable 5 and electrical outlet cable 6 are configured to transmit high voltage power and preferably comprise copper conductors wrapped with a series of shielding layers.

[0033] According to one embodiment, the production distribution system 1 comprises a plurality of electrical input cables 5, each of which serially connects a respective group of wind turbine generators 8 to the floating substations 4. The production distribution system 1 also comprises a plurality of electrical output cables 6, each of which connects the floating substations 4 to a remote station 7.

[0034] More specifically, each electrical lead-in cable 5 extends between successive wind turbine generators 8 (two in the case shown in FIG. 1 ) and between the wind turbine generators 8 and the floating substation 4, with each section resting on the bottom of the seawater 3 as far as the depth allows. Also, each electrical lead-out cable 6 extends between the floating substation 4 and the remote station 7, with each section resting on the bottom of the seawater 3.

[0035] In the particular case described and illustrated herein, a remote station 7 is installed on land at a large distance from the floating substation 4. In particular, the remote station 7 is connected to the power grid 10 and is configured to convert the voltage of the power transmitted by the floating substation 4 to a voltage value suitable for supplying power to the power grid 10. More specifically, the remote station 7 is configured to adjust the voltage of the power transmitted by the floating substation 4 to the voltage of the power grid 10.

[0036] Referring to Figure 2, the floating substation 4 comprises a floating platform 11 having a float 12 configured to receive an upward hydrostatic force from the bottom when at least partially submerged in seawater 3, and an open main deck 13 directly supported by the float 12, and a power management unit 14 arranged on the main deck 13 and configured to receive power from the wind power plant 2 via an electrical input cable 5 (Figures 1, 3, and 4), convert the voltage of the received power, and supply the converted power to the remote station 7 (Figure 1) via an electrical output cable 6 (Figures 1, 3, and 4).

[0037] In particular, the floating platform 11 comprises a single main deck 13 that is supported directly on the floating body 12 and is free of any covering. In other words, the floating platform 11 comprises a single level structure that extends horizontally from one side to the other in both the longitudinal and lateral directions.

[0038] More specifically, the main deck 13 has a substantially quadrilateral shape in design, preferably a substantially square shape.

[0039] In the particular non-limiting case of the invention described and illustrated herein, the floating body 12 comprises a base 15 spaced a distance from the main deck 13 and a plurality of columns 16 connecting the base 15 to the main deck 13.

[0040] More specifically, each spur 16 extends transversely with respect to the main deck 13 and the base 15. In fact, the spurs 16 have the function of supporting the main deck 13 on the surface of the seawater 3, allowing it to float.

[0041] More specifically, the floating body 12 comprises four columns 16, each positioned at a corner of the substantially quadrilateral-shaped main deck 13. In fact, the floating body 12 comprises four through-openings 17, each defined by two adjacent columns 16, the base 15 and the main deck 13.

[0042] According to one embodiment, the base 15 is flat and extends in a plane substantially parallel to the main deck 13 .

[0043] In particular, the base 15 has a substantially rectangular frame shape in design. More specifically, the base 15 comprises four elongate elements 18 (commonly called "pontoons"), each of which extends transversely to the columns 16 and connects two adjacent columns 16 together. In fact, the base 15 comprises a central through-opening 19 defined by the elongate elements 18.

[0044] More specifically, the base 15 and column 16 are divided into watertight compartments via a number of bulkheads not shown in the accompanying drawings so as to ensure that the floating platform 11 remains afloat even in the event that a given number of watertight compartments are flooded.

[0045] Each spar 16 is also configured to accommodate at least one tank, not shown in the accompanying drawings, for storing working liquids such as water or oily liquids. In this way, the center of gravity of the floating platform 11 can be further lowered and said tanks can be located below the main deck 13.

[0046] According to a non-limiting embodiment of the present invention, the power management unit 14 is configured to convert the voltage of the power generated by the wind power plant 2 from about 66 kV to about 230 kV.

[0047] Specifically, power management unit 14 comprises an electrical panel 20 configured to selectively electrically connect / disconnect power management unit 14 to / from electrical inlet cable 5 (FIGS. 1, 3, and 4), and an electrical panel 21 configured to selectively electrically connect / disconnect power management unit 14 to / from electrical outlet cable 6.

[0048] More specifically, each of the electrical panels 20 and 21 includes switching devices, not shown in the accompanying drawings, that are insulated by a pressurized gas, such as sulfur hexafluoride (SF6), and more specifically, the switching devices are commonly referred to as "gas insulated switchgear (GIS)."

[0049] In the particular, non-limiting case of the present invention described and illustrated herein, the floating platform 11 comprises an upper mezzanine 27 disposed above the main deck 13 and supporting the electrical panel 20, and an upper mezzanine 28 disposed above the main deck 13 and supporting the electrical panel 21.

[0050] In particular, the upper mezzanines 27 and 28 are located on the main deck 13 in an arrangement that allows for rapid installation of the electrical incoming and outgoing cables 5 and 6 with minimal dynamic effects due to environmental forces.

[0051] More specifically, the design surface of each mezzanine 27, 28 is smaller than the design surface of the main deck 13. In the specific, non-limiting case of the invention described and illustrated herein, the design extent of each mezzanine 27, 28 is less than one-quarter the design extent of the main deck 13.

[0052] According to one embodiment, the power management unit 14 comprises at least one transformer 22 configured to transform the voltage of the power received from the wind power plant 2 from an input value to an output value greater than the input value.

[0053] In particular, the transformer 22 is configured to convert the voltage of the power received from the wind power plant 2 from 66 kV to 230 kV.

[0054] More specifically, the power management unit 14 comprises two transformers 22, each of which is mounted directly on the main deck 13.

[0055] The power management unit 14 also comprises at least one voltage stabilizer 23 configured to maintain the voltage of the received power within a specified voltage range, even when voltage fluctuations occur, and to adapt the power voltage to the requirements of the production distribution system 1, while simultaneously reducing losses.

[0056] In particular, the power management unit 14 comprises two voltage stabilizers 23, each of which is installed directly on the main deck 13.

[0057] Referring to FIG. 3, the electrical connections between the electrical components of the power management unit 14 are shown.

[0058] Specifically, the power management unit 14 includes an electrical cable 24 electrically connecting the electrical panel 20 to the transformer 22, an electrical cable 25 electrically connecting the transformer 22 to the electrical panel 21, and an electrical cable 26 electrically connecting the electrical panel 21 to the voltage stabilizer 23.

[0059] An electrical inlet cable 5 electrically connects the wind power plant 2 (FIG. 1) to the electrical panel 20, and an outlet cable 6 electrically connects the electrical panel 21 to the remote station 7 (FIG. 1).

[0060] Referring to FIG. 4, the base 15 is shaped to allow passage of the electrical inlet cable 5 and electrical outlet cable 6 through a central through opening 19 .

[0061] More specifically, the electrical input cable 5 is connected to a first elongated element 18 , and the electrical output cable 6 is connected to a second elongated element 18 opposite the first elongated element 18 .

[0062] In use, and with reference to FIG. 1, the wind turbine generator 8 of the wind power plant 2 generates electrical power which is transmitted to the floating substation 4 via the electrical lead-in cable 5 .

[0063] 3, an inlet cable 5 transmits the power generated by the wind power plant 2 to an electrical panel 20. An electrical cable 24 transmits the power from the electrical panel 20 to a transformer 22, which converts the voltage of the received power from an input value to an output value that is greater than the input value. Specifically, the transformer 22 converts the voltage of the received power from approximately 66 kV to approximately 230 kV.

[0064] The converted power is transmitted from the transformer 22 to the electrical panel 21 via an electrical cable 25. Possible fluctuations in the voltage of the power are stabilized via a voltage stabilizer 23 connected to the electrical panel 21 via an electrical cable 26.

[0065] At this point, the converted power is supplied from the electrical panel 21 to the remote station 7 via the electrical lead-out cable 6 .

[0066] Finally, it is obvious that modifications can be made to the invention with respect to the described embodiments without departing from the protective scope of the appended claims. [Explanation of symbols]

[0067] 1. Electricity production and distribution system 2. Wind power plants 3 Seawater 4. Floating Substation 5 Electrical lead-in cable 6 Electrical lead-out cable 7 Remote Station 8. Wind Turbine Generator 9. Foundation 10 Electricity distribution network 11 Floating Platform 12 Floating Body 13 Open Main Deck 14 Power Management Unit 15 base 16 Column 17 Through opening 18 Long Elements 19 Central through opening 20 Electrical Panel No. 1 21 Second Electrical Panel 22 Transformer 23 Voltage Stabilizer 24 Electrical Cables 25 Electrical Cables 26 Electrical Cable 27 Upper Mezzanine 28 Upper Mezzanine

Claims

1. 1. A floating substation for managing power generated by an offshore wind power plant, comprising: a floating platform (11) comprising a floating body (12) configured to receive an upward hydrostatic pressure force from the bottom when at least partially submerged in seawater (3), and an open main deck (13) supported directly on said floating body (12); a power management unit (14) arranged on the main deck (13) and configured to receive power from the wind power plant (2) via at least one electrical input cable (5), to convert the voltage of the received power, and to supply the converted power to a remote station (7) via at least one electrical output cable (6); A floating substation (4) comprising:

2. 2. The floating substation of claim 1, wherein the power management unit (14) comprises at least one first electrical panel (20) configured to selectively electrically connect / disconnect the power management unit (14) to / from the at least one electrical feed-in cable (5).

3. 3. The floating substation according to claim 1 or 2, wherein the power management unit (14) comprises at least one second electrical panel (21) configured to selectively electrically connect / disconnect the power management unit (14) to / from the at least one electrical lead-out cable (6).

4. 4. The floating substation according to claim 1, wherein the power management unit (14) comprises at least one transformer (22) configured to convert the voltage of the power received from the wind power plant (2) from an input value to an output value that is greater than the input value.

5. A floating substation according to any one of claims 1 to 4, wherein said main deck (13) has a substantially quadrilateral shape in design, preferably a substantially square shape.

6. 6. The floating substation of claim 5, wherein the floating body (12) comprises a base (15) installed at a distance from the main deck (13), and a plurality of columns (16) connecting the base (15) to the main deck (13).

7. 7. The floating substation of claim 6, wherein the floating body (12) comprises four stilts (16), each stilt located at a corner of the substantially quadrilateral shape of the main deck (13).

8. 8. A floating substation according to claim 6 or 7, wherein the base (15) is preferably provided with a central through-opening (19) to allow passage of the at least one electrical input cable (5) and the at least one electrical output cable (6) through the central through-opening (19).

9. 9. The floating substation according to claim 8, wherein said base (15) has a substantially rectangular frame shape in design.

10. an offshore wind power plant (2) arranged in seawater (3) and configured to generate electricity, preferably comprising at least one wind turbine generator (8); - a floating substation (4) according to any one of claims 1 to 9; - at least one electrical lead-in cable (5) electrically connecting said wind power plant (2) to said floating substation (4) for transmitting power from said wind power plant (2) to said floating substation (4); - at least one electrical lead-out cable (6) electrically connecting said floating substation (4) to said remote station (7) for transmitting power from said floating substation (4) to said remote station (7); An electric power production and distribution system comprising:

11. 1. A distribution method for managing power generated by an offshore wind power plant, comprising: - placing a power management unit (14) on the open main deck (13) of a floating platform (11) installed in seawater (3); - transmitting power from said wind power plant (2) to said power management unit (14); - converting the voltage of the transmitted power by the power management unit (14); - supplying said converted power from said power management unit (14) to a remote station (7); A method of distribution comprising:

12. 12. The method of claim 11, comprising selectively electrically connecting / disconnecting the power management unit (14) to / from the wind power plant (2) via a first electrical panel (20) of the power management unit (14).

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

14. 14. The method of claim 11, wherein the voltage of the power transmitted from the wind power plant to the power management unit is converted from an input value to an output value greater than the input value.

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