WO2023090995A1 - An improved offshore wind turbine - Google Patents

An improved offshore wind turbine Download PDF

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Publication number
WO2023090995A1
WO2023090995A1 PCT/MY2022/050115 MY2022050115W WO2023090995A1 WO 2023090995 A1 WO2023090995 A1 WO 2023090995A1 MY 2022050115 W MY2022050115 W MY 2022050115W WO 2023090995 A1 WO2023090995 A1 WO 2023090995A1
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WO
WIPO (PCT)
Prior art keywords
wind turbine
tower
nacelle
platform
offshore wind
Prior art date
Application number
PCT/MY2022/050115
Other languages
French (fr)
Inventor
Izleena Bt M IQBAR
Fauzy Omar BASHEER B OSMAN
Original Assignee
Petroliam Nasional Berhad (Petronas)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Petroliam Nasional Berhad (Petronas) filed Critical Petroliam Nasional Berhad (Petronas)
Publication of WO2023090995A1 publication Critical patent/WO2023090995A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D7/00—Controlling wind motors 
    • F03D7/02—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D13/00—Assembly, mounting or commissioning of wind motors; Arrangements specially adapted for transporting wind motor components
    • F03D13/20—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors
    • F03D13/25—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors specially adapted for offshore installation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D80/00—Details, components or accessories not provided for in groups F03D1/00 - F03D17/00
    • F03D80/30—Lightning protection
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
    • B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
    • B63B2035/4433—Floating structures carrying electric power plants
    • B63B2035/446—Floating structures carrying electric power plants for converting wind energy into electric energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
    • B63B21/50—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers
    • B63B21/502—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers by means of tension legs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00—Components
    • F05B2240/57—Seals
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00—Components
    • F05B2240/90—Mounting on supporting structures or systems
    • F05B2240/93—Mounting on supporting structures or systems on a structure floating on a liquid surface
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

Definitions

  • the invention relates to the generation of electricity from wind drive turbines.
  • the invention relates to wind turbine structures based offshore.
  • Offshore oil and gas platforms are situated in water depths often times more than 50m which require floating substructures.
  • the power generation is normally based on turbo fired machineries utilize fuel gas and susceptible to carbon emissions.
  • the invention provides an offshore wind turbine structure comprising: a rotor nacelle assembly comprising a three-blade horizontal axis turbine supported by a tower; a tension leg platform arranged to support the tower and rotor nacelle assembly; a control system arranged to control pitch and yaw of said blades as a function of electricity loss.
  • the wind turbine control system is adapted for low wind speed region by optimised to maximizing power take-off and minimize the electricity losses. In so doing the electricity losses may be reduced to 50 kW and consequently, maximising available power generation which may otherwise be lost during such a low wind environment.
  • Figure 1 is an elevation view of an offshore wind turbine according to one embodiment of the present invention
  • FIGS. 2A and 2B are various views of a lightning discharge ring according to one embodiment of the present invention.
  • Figures 3A to 3D are various views of a tower assembly according to one embodiment of the present invention
  • Figures 4A and 4B are isometric views of tower sections according to a further embodiment of the present invention, and;
  • Figure 5 is a schematic view of a nacelle for an offshore wind turbine according to one embodiment of the present invention.
  • the invention seeks to address some of the major impediments in the implementation of offshore wind power generation, such as: i) Low wind speed; ii) Component & System Integration iii) Lightning Protection, and; iv) Corrosion.
  • the invention is directed to a floating offshore wind turbine integrated with an offshore structure such as but not limiting to, the Oil and Gas Platform as shown in Figure 1.
  • FIG. 1 shows one embodiment of an improved offshore wind turbine 5 according to one embodiment of the present invention.
  • the nacelle 15 is supported on a tower 20. Wind drives the rotor 10, which then generates power within the nacelle 15, for eventual delivery.
  • the tower 20 is connected at point T to a tension leg platform 40, which comprises supporting elements 44 directing the weight of the tower and wind turbine to the substructure 42.
  • the substructure provides the floating platform with excess buoyancy, with the platform 40 being vertically moored to the seabed 30 by mooring lines 35, acting in tension, to an anchor 25.
  • the structure is vertically restrained from vertical movement, as well as restricted in rotation about the vertical axis of the wind turbine.
  • a feature that enhances the suitability of offshore wind power generation is the ability to remain viable in low wind speed conditions.
  • the wind turbine is designed to decrease specific power ration.
  • the specific power ratio may be reduced to 152 W/mw.
  • the rotor size may be increased up to 129m.
  • the wind turbine control system for low wind speed region may be optimised to maximize power take-off and minimize the electricity losses. In so doing the electricity losses may be reduced to 50 kW by tuning the generators and improving the algorithm for yawing and pitching.
  • a control system may control yawing and pitching as a function of electricity loss, rather than maximising power.
  • the system is directed to a specific arrangement and integration of the wind turbine, electrical components and floating substructure as shown in Table 1.
  • the wind turbine structure includes a rotor nacelle assembly (RNA), tower, lift and cranes.
  • RNA rotor includes a three-blade horizontal axis upwind turbine with blade pitch to regulate the power, a nacelle system and a tower.
  • the electrical components may include converters, inverters, energy storage system (ESS) and cooling system.
  • the floating substructure may include a tension leg platform (TLP), mooring lines, crane, grid cable, anchors be it gravity-based anchors sitting on the seabed.
  • Blades are part of the rotor of the wind turbine, and may be made of a composite material.
  • the length may be more than 63 metres.
  • the leading edge in the tip may be protected against pitting, wear and penetrating water.
  • Other arrangements are also possible, which will fit within the scope of the invention.
  • the tower 65 may be part of the support structure of the system to cany the nacelle.
  • the hub height of the wind turbine may be above the sea level by not less than 100m.
  • the tower 65 may be designed as a tubular steel tower supported by a floating offshore foundation (tension leg platform (TLP)).
  • TLP tension leg platform
  • the tower may have three sections 70, 75, 80, with the first section 80 being cylindrical (tower bottom) and the second 75 and third 70 being conical. The shape changes from cylindrical to conical at a height of about 5m.
  • a ladder with climbing protection system and rest platforms may be required. At least one platform for each section is scheduled. A lift guided on the ladder may be required.
  • electrical components may be installed. These are situated on two platforms within the first section. The access door leads to the platform at lowest level. Further electrical installation may be intended inside the tower such as cable routes for the main power transmission, the supply voltage and the lightning protection.
  • Figures 4A and 4B show the placing of electrical devices 90, 95, 100, 115, door, ladder and service lift in the bottom section having Platform #1 85 and Platform #2 100.
  • the access door is placed in the bottom section near the foundation top edge (Platform #1). It has to have a size of at least 1.8 meter by 0.7 meter.
  • the tower 65 may contain 4 platforms as described in the following list. All platforms cover the tower section completely except cuts for ladder / service lift and cables.
  • Entry platform a. Height: approximately 1 meter above foundation top edge b. Diameter: approximately 5.8 meters
  • Mounting platform SI - S2 a. Height: approximately 4.75 meters above foundation top edge b. Diameter: approximately 5.8meters
  • Mounting platform S32 - S3 a. Height: approximately 40.07 meters above foundation top edge b. Diameter: approximately 4.45 meters
  • Mounting platform S3 - YAW a. Height: approximately 80.73 meters above foundation top edge. b. Diameter: approximately 3.0 meters The ladder starts 180 mm above foundation top edge and ends shortly below the mounting platform S3-YAW. There is a for ladder between lift exist platform (top of tower) and platform S3-YAW. The ladders are designed for use with a ladder guided service lift and for climbing with the nose to the tower wall. Openings in the platforms for the service lift and ladders are secured with rails with the following requirements: a. Rail height 1100 mm. b. Doors close: automatically. c. Doors provided with interlock.
  • the service lift starts at the entry platform and ends at the exit platform ca. 5 meters underneath the top flange.
  • This lift is capable to move up to 300kg and to fit to the ladder system of the tower.
  • the main cables from the cable loop to the bottom are guided on the left side of the ladder.
  • the cables for 230 V/ 400 V and control cables are guided on the right side of the ladder.
  • the tower is lit evenly where the lamps are installed on the right side of the low voltage cables.
  • the tower flanges contain welding bushes for cable bridges transmit the lightning current.
  • the complete tower has to meet all the requirements of corrosion protection class (with protection of more than 15 years): a. Outside (stress zone 3) : class CX b. Inside (stress zone 4): class C4
  • the operational conditions are determined by the on-site micro grid requirements and power to grid concept. From operational control point of view, there exists three different working schemes; battery loading regime where turbine is producing up to rated capacity, complete power supply where turbine is producing up to the required load and partial power supply where turbine is producing up to the set required partial load.
  • the following quantities should be according to and compliant to our micro grid and / or grid requirements while operating the wind turbine; power factor regulation, power curtailment, voltage range and control, remote voltage control frequency, flicker, harmonics, fault ride-through (FRT) requirements and repeating fault sequences.
  • the basic requirement for the power and energy management is to provide a continuous and secure power supply to the user, for example, an offshore oil and gas platform.
  • the wind turbine may be integrated with the multi-source converters and ESS will contribute this concept.
  • the energy management system has to ensure a smooth transition of ramping up the gas turbine to the required load in case of system failure to prevent power outages.
  • the ESS objective is to keep the amount the electricity produced constant over a period during fluctuation of power generation.
  • the complete electric equipment will be integrated into the tower base located directly above the floating platform.
  • the TLP 5 is based on the stability due to buoyancy principle.
  • the geometry layout is quadratic with buoyancy bodies 42 at the comers.
  • Everything below the tower base flange T in Figure 1 is identified as floating sub structure 40.
  • Parts of the floating substructure 40 include one upper node to mount the tower 20 to the substructure, an upper node supporting structure 44 consisting of four inclined cantilever beams, four middle nodes to connect the cantilever beams to the vertical pipes, four vertical pipes, four lower nodes to connect the vertical pipes to the horizontal pipes, four horizontal pipes, four vertical, cylindrical buoyancy bodies, tow boat landings, one service crane, work / access platforms and walkways and ladders.
  • Parts of the station keeping system are minimum four and maximum 8 pre-stressed mooring lines (tendons) 35 as connection to the gravity anchor and one gravity anchor 25 (reinforced concrete structure) with shear resistance elements.
  • the TLP 5 is connected with gravity anchor 25 by mooring lines (tendons) 35 and specific connector and interface elements comprises of the following parts; maximum of a. 8 off vertical mooring lines b. 8 bottom tendon connectors c. 8 top tendon connectors d. 8 interface elements at TLP side e. 8 interface elements at gravity anchor side
  • a permanent winch / crane will be installed in order to lift loads up to 400kg between tower bottom and nacelle.
  • a device On the ground floor of the tower, a device should be installed to assist material handling through the tower door.
  • the system will be equipped with a suitable offshore cooling system according to site environmental conditions.
  • the tower bottom (Platform 1 and 2) containing electrical cabinets (power electronics, controller, ESS) will have sufficient cooling suitable for offshore application.
  • Power electronics, controller, ESS power electronics, controller, ESS
  • the sealing system has to have a lifetime of 25 years and must be able to withstand internal and external conditions of the wind turbine during the complete lifetime.
  • the outside air will be filtered and dried by the nacelle filtering system 135 and blown into the nacelle. By this procedure, the air will generate a positive pressure inside of the nacelle.
  • the air will leave the nacelle by clearly defined outlet openings 140A, MOB at the bottom side of the nacelle. In case of small, unexpected openings, the air will go through these openings and will prevent the turbine from contamination with outside air.
  • the air filtering and ventilation system have to have the capacity to generate a positive pressure of minimum 20 mbar under all conditions during the lifetime of the turbine.
  • a pressure sensor has to be installed to monitor the value of 20 mbar. If deviations detected, the system has to provide this information to the operating system.
  • the ventilation system has to be designed with a redundant system.
  • a positive pressure has to be realized in the complete wind turbine including tower and floating offshore foundation. The humidity inside the turbine and tower assembly has to be monitored by suitable sensors to be connected to the turbine controller.
  • Wind turbines are often struck by lightning because of their special shape, their tall structure and being placed in the open air. Besides seriously damaging the blades, lightning results in accidents in which low-voltage and control circuit breakdowns frequently occur in many wind farms worldwide.
  • the wind turbine is designed for lightning protection according to site conditions.
  • the blade lightning protection system should be composed of a metal blade tip lightning arrester, suitable number of blade body lightning receptors, a lightning conducting cable and a lightning discharge ring as shown in Figures 2A and 2B.
  • the lightning discharge ring assembly 45 is specifically designed by the wind turbine manufacturer.
  • the lightning discharge ring includes the discharge ring 50, electrically isolated from the blade by a ring platform 55, which I, in turn, mounted to the blade through an isolating adhesive 60.
  • the discharge ring is then connected to a grounded lightning conducting cable (not shown).
  • the connection has to be in the area of the trailing edge.
  • the overall resistance of lightning transmission cable is ⁇ 50mQ.

Abstract

An offshore wind turbine structure comprising: a rotor nacelle assembly comprising a three- blade horizontal axis turbine supported by a tower; a tension leg platform arranged to support the tower and rotor nacelle assembly; a control system arranged to control pitch and yaw of said blades as a function of electricity loss.

Description

AN IMPROVED OFFSHORE WIND TURBINE
Field of Invention
The invention relates to the generation of electricity from wind drive turbines. In particular, the invention relates to wind turbine structures based offshore.
Background
Offshore oil and gas platforms are situated in water depths often times more than 50m which require floating substructures. The power generation is normally based on turbo fired machineries utilize fuel gas and susceptible to carbon emissions.
In solution may be to implement a renewable energy system. However, wind turbine systems are generally not cost effective for weak wind areas where the annual average wind speed at hub height is smaller than 7.5m/s. For economic reasons offshore wind turbines are designed for IEC class II and class I wind speed sites (i.e. annual average wind speed larger than 8.5 m/s, 10 m/s respectively) while onshore we can get class S to cater for weak wind areas. For a floating foundation this is even more restrictive as they are designed “to follow” the high wind speed sites. In contrast to this situation the demand is to install CO2 effective, hence renewable electrical generators with high power density (i.e. wind turbine generators) to support industrial plants that cannot follow the wind but are bound to local offshore oil and gas resources. This leads to the severe problem of establishing a techno-economically viable offshore wind turbine system in weak wind regions.
Summary of Invention In a first aspect, the invention provides an offshore wind turbine structure comprising: a rotor nacelle assembly comprising a three-blade horizontal axis turbine supported by a tower; a tension leg platform arranged to support the tower and rotor nacelle assembly; a control system arranged to control pitch and yaw of said blades as a function of electricity loss.
Therefore, the wind turbine control system is adapted for low wind speed region by optimised to maximizing power take-off and minimize the electricity losses. In so doing the electricity losses may be reduced to 50 kW and consequently, maximising available power generation which may otherwise be lost during such a low wind environment.
Brief Description of Drawings
It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible and consequently, the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.
Figure 1 is an elevation view of an offshore wind turbine according to one embodiment of the present invention;
Figure 2A and 2B are various views of a lightning discharge ring according to one embodiment of the present invention;
Figures 3A to 3D are various views of a tower assembly according to one embodiment of the present invention; Figures 4A and 4B are isometric views of tower sections according to a further embodiment of the present invention, and;
Figure 5 is a schematic view of a nacelle for an offshore wind turbine according to one embodiment of the present invention.
Detailed Description
The invention seeks to address some of the major impediments in the implementation of offshore wind power generation, such as: i) Low wind speed; ii) Component & System Integration iii) Lightning Protection, and; iv) Corrosion.
In one aspect, the invention is directed to a floating offshore wind turbine integrated with an offshore structure such as but not limiting to, the Oil and Gas Platform as shown in Figure 1.
Figure 1 shows one embodiment of an improved offshore wind turbine 5 according to one embodiment of the present invention. The nacelle 15 is supported on a tower 20. Wind drives the rotor 10, which then generates power within the nacelle 15, for eventual delivery. The tower 20 is connected at point T to a tension leg platform 40, which comprises supporting elements 44 directing the weight of the tower and wind turbine to the substructure 42.
The substructure provides the floating platform with excess buoyancy, with the platform 40 being vertically moored to the seabed 30 by mooring lines 35, acting in tension, to an anchor 25. The structure is vertically restrained from vertical movement, as well as restricted in rotation about the vertical axis of the wind turbine. Low Wind Speed
A feature that enhances the suitability of offshore wind power generation is the ability to remain viable in low wind speed conditions.
To this end, in one embodiment of the present invention, the wind turbine is designed to decrease specific power ration. In a one embodiment, the specific power ratio may be reduced to 152 W/mw. In one example, for the generator rated power of 2.5 MW, the rotor size may be increased up to 129m.
In a further embodiment, the wind turbine control system for low wind speed region may be optimised to maximize power take-off and minimize the electricity losses. In so doing the electricity losses may be reduced to 50 kW by tuning the generators and improving the algorithm for yawing and pitching. Thus, in a further embodiment, a control system may control yawing and pitching as a function of electricity loss, rather than maximising power.
Component & System Integration In a further aspect of the invention, the system is directed to a specific arrangement and integration of the wind turbine, electrical components and floating substructure as shown in Table 1.
Figure imgf000006_0001
Figure imgf000007_0001
The wind turbine structure includes a rotor nacelle assembly (RNA), tower, lift and cranes. The RNA rotor includes a three-blade horizontal axis upwind turbine with blade pitch to regulate the power, a nacelle system and a tower. The electrical components may include converters, inverters, energy storage system (ESS) and cooling system. The floating substructure may include a tension leg platform (TLP), mooring lines, crane, grid cable, anchors be it gravity-based anchors sitting on the seabed.
Blades are part of the rotor of the wind turbine, and may be made of a composite material.
By way of example, for a 2.5MW turbine, the length may be more than 63 metres. The leading edge in the tip may be protected against pitting, wear and penetrating water. Other arrangements are also possible, which will fit within the scope of the invention.
An indicative overview of tower geometiy is shown in Figures 3A to 3D. The tower 65 may be part of the support structure of the system to cany the nacelle. The hub height of the wind turbine may be above the sea level by not less than 100m. The tower 65 may be designed as a tubular steel tower supported by a floating offshore foundation (tension leg platform (TLP)). The tower may have three sections 70, 75, 80, with the first section 80 being cylindrical (tower bottom) and the second 75 and third 70 being conical. The shape changes from cylindrical to conical at a height of about 5m. To assure a safe ascent / descend inside the tower, a ladder with climbing protection system and rest platforms may be required. At least one platform for each section is scheduled. A lift guided on the ladder may be required. At the bottom of the tower, electrical components may be installed. These are situated on two platforms within the first section. The access door leads to the platform at lowest level. Further electrical installation may be intended inside the tower such as cable routes for the main power transmission, the supply voltage and the lightning protection.
Figures 4A and 4B show the placing of electrical devices 90, 95, 100, 115, door, ladder and service lift in the bottom section having Platform #1 85 and Platform #2 100. The access door is placed in the bottom section near the foundation top edge (Platform #1). It has to have a size of at least 1.8 meter by 0.7 meter.
In a further embodiment, the tower 65 may contain 4 platforms as described in the following list. All platforms cover the tower section completely except cuts for ladder / service lift and cables.
1. Entry platform: a. Height: approximately 1 meter above foundation top edge b. Diameter: approximately 5.8 meters
2. Mounting platform SI - S2: a. Height: approximately 4.75 meters above foundation top edge b. Diameter: approximately 5.8meters
3. Mounting platform S32 - S3 : a. Height: approximately 40.07 meters above foundation top edge b. Diameter: approximately 4.45 meters
4. Mounting platform S3 - YAW: a. Height: approximately 80.73 meters above foundation top edge. b. Diameter: approximately 3.0 meters The ladder starts 180 mm above foundation top edge and ends shortly below the mounting platform S3-YAW. There is a for ladder between lift exist platform (top of tower) and platform S3-YAW. The ladders are designed for use with a ladder guided service lift and for climbing with the nose to the tower wall. Openings in the platforms for the service lift and ladders are secured with rails with the following requirements: a. Rail height 1100 mm. b. Doors close: automatically. c. Doors provided with interlock.
The service lift starts at the entry platform and ends at the exit platform ca. 5 meters underneath the top flange. This lift is capable to move up to 300kg and to fit to the ladder system of the tower. The main cables from the cable loop to the bottom are guided on the left side of the ladder. The cables for 230 V/ 400 V and control cables are guided on the right side of the ladder. The tower is lit evenly where the lamps are installed on the right side of the low voltage cables. The tower flanges contain welding bushes for cable bridges transmit the lightning current. The complete tower has to meet all the requirements of corrosion protection class (with protection of more than 15 years): a. Outside (stress zone 3) : class CX b. Inside (stress zone 4): class C4
The operational conditions are determined by the on-site micro grid requirements and power to grid concept. From operational control point of view, there exists three different working schemes; battery loading regime where turbine is producing up to rated capacity, complete power supply where turbine is producing up to the required load and partial power supply where turbine is producing up to the set required partial load. The following quantities should be according to and compliant to our micro grid and / or grid requirements while operating the wind turbine; power factor regulation, power curtailment, voltage range and control, remote voltage control frequency, flicker, harmonics, fault ride-through (FRT) requirements and repeating fault sequences. The basic requirement for the power and energy management is to provide a continuous and secure power supply to the user, for example, an offshore oil and gas platform. The wind turbine may be integrated with the multi-source converters and ESS will contribute this concept. The energy management system has to ensure a smooth transition of ramping up the gas turbine to the required load in case of system failure to prevent power outages. Also, the ESS objective is to keep the amount the electricity produced constant over a period during fluctuation of power generation. The complete electric equipment will be integrated into the tower base located directly above the floating platform.
Referring back to Figure 1, the TLP 5 is based on the stability due to buoyancy principle. The geometry layout is quadratic with buoyancy bodies 42 at the comers. Everything below the tower base flange T in Figure 1 is identified as floating sub structure 40. Parts of the floating substructure 40 include one upper node to mount the tower 20 to the substructure, an upper node supporting structure 44 consisting of four inclined cantilever beams, four middle nodes to connect the cantilever beams to the vertical pipes, four vertical pipes, four lower nodes to connect the vertical pipes to the horizontal pipes, four horizontal pipes, four vertical, cylindrical buoyancy bodies, tow boat landings, one service crane, work / access platforms and walkways and ladders. Parts of the station keeping system are minimum four and maximum 8 pre-stressed mooring lines (tendons) 35 as connection to the gravity anchor and one gravity anchor 25 (reinforced concrete structure) with shear resistance elements. The TLP 5 is connected with gravity anchor 25 by mooring lines (tendons) 35 and specific connector and interface elements comprises of the following parts; maximum of a. 8 off vertical mooring lines b. 8 bottom tendon connectors c. 8 top tendon connectors d. 8 interface elements at TLP side e. 8 interface elements at gravity anchor side
Corrosion
In the nacelle, a permanent winch / crane will be installed in order to lift loads up to 400kg between tower bottom and nacelle. On the ground floor of the tower, a device should be installed to assist material handling through the tower door. The system will be equipped with a suitable offshore cooling system according to site environmental conditions. The tower bottom (Platform 1 and 2) containing electrical cabinets (power electronics, controller, ESS) will have sufficient cooling suitable for offshore application. As shown in Figure 5, to maximise the air inside the turbine is dry and salt free, a positive pressure has to be installed. With respect to this requirement, all gaps in the body 130 of the nacelle 125 have to be sealed with suitable methods and sealing systems. The sealing system has to have a lifetime of 25 years and must be able to withstand internal and external conditions of the wind turbine during the complete lifetime. The outside air will be filtered and dried by the nacelle filtering system 135 and blown into the nacelle. By this procedure, the air will generate a positive pressure inside of the nacelle. The air will leave the nacelle by clearly defined outlet openings 140A, MOB at the bottom side of the nacelle. In case of small, unexpected openings, the air will go through these openings and will prevent the turbine from contamination with outside air. The air filtering and ventilation system have to have the capacity to generate a positive pressure of minimum 20 mbar under all conditions during the lifetime of the turbine. To ensure that the system is working according to this requirement, a pressure sensor has to be installed to monitor the value of 20 mbar. If deviations detected, the system has to provide this information to the operating system. To ensure that the positive pressure can be realized under all conditions in all situations, the ventilation system has to be designed with a redundant system. A positive pressure has to be realized in the complete wind turbine including tower and floating offshore foundation. The humidity inside the turbine and tower assembly has to be monitored by suitable sensors to be connected to the turbine controller.
Lightning Protection
Tall structures are attractive to lightning, especially when located in flat planes with nothing much else around, as wind turbines often are. Wind turbines are often struck by lightning because of their special shape, their tall structure and being placed in the open air. Besides seriously damaging the blades, lightning results in accidents in which low-voltage and control circuit breakdowns frequently occur in many wind farms worldwide.
Consequently, the wind turbine is designed for lightning protection according to site conditions. The blade lightning protection system should be composed of a metal blade tip lightning arrester, suitable number of blade body lightning receptors, a lightning conducting cable and a lightning discharge ring as shown in Figures 2A and 2B. The lightning discharge ring assembly 45 is specifically designed by the wind turbine manufacturer. The lightning discharge ring includes the discharge ring 50, electrically isolated from the blade by a ring platform 55, which I, in turn, mounted to the blade through an isolating adhesive 60. The discharge ring is then connected to a grounded lightning conducting cable (not shown). The connection has to be in the area of the trailing edge. The overall resistance of lightning transmission cable is < 50mQ.

Claims

An offshore wind turbine structure comprising: a rotor nacelle assembly comprising a three-blade horizontal axis turbine supported by a tower; a tension leg platform arranged to support the tower and rotor nacelle assembly; a control system arranged to control pitch and yaw of said blades as a function of electricity loss. The offshore wind turbine structure according to claim 1, wherein said electricity loss to 50kW. The offshore wind turbine structure according to claim 1, wherein said nacelle arranged to be sealed, a filtering system mounted to the nacelle arranged to blow air into the nacelle and outlets for venting air; said filtering system arranged to maintain a positive pressure in said nacelle. The offshore wind turbine structure according to claim 1, further including a lightning discharge ring assembly coupled to each blade; said lightning discharge ring assembly comprising a lightning discharge ring connected to a grounded lightning conducting cable, said lightning discharge ring mounted to a platform, said platform adhered to said blade; wherein the lightning discharge ring is electrically isolated from the blade, by the platform.
PCT/MY2022/050115 2021-11-19 2022-11-18 An improved offshore wind turbine WO2023090995A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005302399A (en) * 2004-04-08 2005-10-27 Kanazawa Inst Of Technology Wind power system
US20100133830A1 (en) * 2009-10-29 2010-06-03 Friedrich Loh Systems and methods for assembling a pitch assembly for use in a wind turbine
EP2853734A1 (en) * 2013-09-26 2015-04-01 Mitsubishi Heavy Industries, Ltd. Ventilation system for a renewable energy power generating apparatus
US20170045037A1 (en) * 2015-08-10 2017-02-16 Nordex Energy Gmbh Wind turbine rotor blade having a spark gap
CN112648149A (en) * 2021-01-04 2021-04-13 上海电气风电集团股份有限公司 Marine formula fan basis and offshore wind turbine that floats

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005302399A (en) * 2004-04-08 2005-10-27 Kanazawa Inst Of Technology Wind power system
US20100133830A1 (en) * 2009-10-29 2010-06-03 Friedrich Loh Systems and methods for assembling a pitch assembly for use in a wind turbine
EP2853734A1 (en) * 2013-09-26 2015-04-01 Mitsubishi Heavy Industries, Ltd. Ventilation system for a renewable energy power generating apparatus
US20170045037A1 (en) * 2015-08-10 2017-02-16 Nordex Energy Gmbh Wind turbine rotor blade having a spark gap
CN112648149A (en) * 2021-01-04 2021-04-13 上海电气风电集团股份有限公司 Marine formula fan basis and offshore wind turbine that floats

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