Abstract: A power transmission and distribution system suitable for subsea electrical loads includes a primary dc transmission cable connected to an onshore AC/DC converter module that connects the onshore end of the cable to an ac supply network. The subsea end of the cable is connected to a primary subsea power distribution unit and includes a DC/DC converter module having a modular topology with a series of interconnected DC/DC converter units. The DC/DC converter module is connected between the cable and a primary dc distribution network. Secondary dc transmission cables and associated circuit breakers connect the primary subsea power distribution unit to secondary subsea power distribution units that are located near the subsea loads. Each secondary subsea power distribution unit includes a DC/DC converter module having a modular topology with a series of interconnected DC/DC converter units. Respective secondary dc distribution networks supply power to one or more subsea loads.

Abstract: An electrical machine 20, 48 comprises a first stator 22 and a second stator 24 spaced from the first stator 22, at least one of the first stator 22 and the second stator 24 including a guide arrangement 26, 50. The electrical machine 20, 48 also includes a plurality of rotor elements 30, 46 located between the first stator 22 and the second stator 24 and cooperating with the guide arrangement 26, 50 for movement relative to the first stator 22 and the second stator 24. Adjacent rotor elements 30, 46 cooperate with each other so that the rotor elements 30, 46 form a rotor and at least one of the rotor elements 30, 46 includes a coupling element 32 to transfer force to or from the rotor.

Abstract: A dc energy store includes auxiliary systems operable in different modes, including self-supporting, island mode and normal modes. In the self-supporting mode a first controller uses a voltage demand signal indicative of desired ac voltage of an AC/DC power converter to control semiconductor power switching devices to achieve the desired level of ac voltage. The voltage demand signal is derived from comparing a voltage feedback signal and a second voltage demand signal preset to provide the desired ac voltage for the auxiliary systems. A second controller uses a current demand signal indicative of the desired dc link current to control the semiconductor power switching devices of a DC/DC power converter to achieve the desired level of dc link current. The current demand signal is derived from comparing a dc link voltage demand signal indicative of a desired dc link voltage and a dc link voltage feedback signal.

Abstract: A taut cable with a fiber optic cable with Bragg diffusion gratings allows a suitable driver circuit to determine the shape of the taut cable at a large number of points along its length. This enables the total 3-dimensional shape of the taut cable to be estimated and from which the position of the vessel relative to a seabed weight attached to the taut cable can be inferred.

Abstract: A method of estimating the environmental force acting on a supported jack-up vessel is described. The vessel is positioned in a force determination position and the strain on at least one support leg of the jack-up vessel is measured while a first thrust is applied to the vessel. A second thrust is applied to the vessel while the vessel is maintained in the force determination position. The variation in the strain in the at least one support leg is monitored as the second thrust is applied and the strain is used to calculate an estimate of the environmental force acting on the vessel. The method allows a dynamic positioning (DP) system of the jack-up vessel to determine a suitable thrust to apply to the vessel as the support legs of the vessel are raised. By applying this suitable thrust the position of the vessel can be maintained when the vessel transitions from being supported by the support legs to being supported by water.

Abstract: A wind turbine typically includes a generator and a rotating mechanical system having a natural period. The present invention relates to a method of controlling generator torque that minimizes oscillations in the speed of the generator rotor. In the event of a grid fault or transient, or a fault in the power converter, the generator torque is decreased at a substantially constant rate with respect to time. The rate at which the generator torque is decreases is proportional to the nominal rated torque of the generator and inversely proportional to an integer multiple of the natural period of the rotating mechanical system.

Abstract: A reactive energy compensator is provided. The compensator is connected to an alternating electrical network including M phase(s), M being an integer greater than or equal to 1. The compensator includes M connection terminals, N banks of capacitor(s) capable of providing reactive energy, N being an integer greater than or equal to 2, N two-way voltage inverters, connected to each other in parallel and each connected to a unique capacitor bank, each inverter being able to convert a direct current into an alternating current including M phase(s) in one direction and the alternating current into direct current in the other direction, each inverter including first and second input terminals and M output terminal(s), the input terminals being connected to the corresponding capacitor bank, each output terminal corresponding to a phase of the alternating current and being connected to a corresponding connection terminal, and a device for balancing the voltage of the N capacitor banks.

Abstract: A method of operating a dual fed system is described where power is supplied to a electrical load from first and second ac busbars at a ratio that achieves a desired level of exhaust emissions such as nitrogen oxides (NOx), carbon dioxide (CO2) and other pollutants produced by the prime movers associated with generators. Preferably, the method may be used to operate a dual fed marine propulsion system wherein the electrical load is a thruster. Operating a dual fed marine propulsion system using the method of the present invention makes it possible to optimise thrust allocation between thrusters in a way that is similar to that used in conventional dynamic positioning (DP) systems and then share or allocate the required power between generators to minimise exhaust emissions.

Abstract: A blade for a water current turbine rotor, which extends along a radial direction and comprises an outer surface, an inner surface, a leading edge, and a trailing edge. The leading edge is the edge of the blade that extends along the radial direction and is disposed upstream in the direction in which the water flows along the blade, while the trailing edge is the edge of the blade opposite the leading edge and is disposed downstream in the direction of flow. At least one portion of the blade has a profile comprising a thick portion and a thin portion, the cross section being perpendicular to the radial direction. The thick portion and the thin portion each have a maximum thickness along a direction perpendicular to the outer surface, the maximum thickness of the thick portion being at least four times greater than the maximum thickness of the thin portion.

Abstract: A high vacuum component, e.g. a vacuum chamber wall or a component that is operated or positioned within a vacuum chamber in use is described. The component is substantially formed of a layered material comprising a fibrous composite material layer having a surface that is coated with a copper intermediate layer and an impermeable outer layer of nickel. In use the outer layer is exposed to a high vacuum.

Abstract: A method of operating a power converter arrangement, the power converter arrangement includes a dc link and a dc load/source, an active rectifier/inverter having dc terminals connected to the dc link and is adapted to provide a variable dc link voltage between a maximum and a minimum limits, an interleaved buck converter having a plurality of converter circuits connected between the dc link and the dc load/source, wherein each converter circuit includes a first switch, a second switch, and a reactor, the method including determining one or more null values of dc link voltage with reference to the voltage across the dc load/source, and if a null value of dc link voltage is between the maximum and the minimum limits, controlling the active rectifier/inverter to provide a dc link voltage that is substantially the same as the null value of dc link voltage.

Abstract: A structural component that experiences a changing magnetic field during use is described. The structural component can be a stator bore tube, a stator tooth or stator support, for example. A stator bore tube is made of a multi-layered composite material with layers of unidirectional carbon fibre reinforced polymer (CFRP). The eddy current direction is along the axis of the stator bore tube. The carbon fibres in the CFRP layers are orientated along the circumferential direction of the stator bore tube.

Abstract: A heat sink is disclosed including a cold plate, a plurality of heat pipes, and a plurality of fins. The cold plate has a first surface arranged substantially vertical and adapted to thermally couple to a heat source. Each of the plurality of heat pipes have an evaporator section arranged substantially vertical and thermally coupled to the cold plate, a condenser section arranged at an incline, and a single bend section coupling the evaporator section and the condenser section. The plurality of fins are thermally coupled to the condenser sections of the plurality of heat pipes.

Abstract: A heat sink is disclosed including a cold plate, a plurality of heat pipes, a plurality of fins, and a heating unit. The cold plate has a first surface adapted to thermally couple to a heat source. Each of the heat pipes has an evaporator section thermally coupled to the cold plate and a condenser section coupled to the evaporator section. The plurality of fins are thermally coupled to the condenser sections of the plurality of heat pipes. The heating unit is adapted to heat condenser sections of a subset of the plurality of heat pipes.

Abstract: A system for maintaining a high vacuum in a vacuum enclosure such as cryostat, for example, is described. The system includes a high-vacuum pump having an input that is connected to the cryostat and an output. A vacuum vessel is connected to the output of the high-vacuum pump. A second vacuum pump is connectable to the vacuum vessel. The system is operated such that the high-vacuum pump maintains the cryostat at a high vacuum and the second vacuum pump is periodically operated to maintain the pressure of the vacuum vessel below a threshold pressure. The second vacuum pump may be either permanently connected to, or removable from, the vacuum vessel. The vacuum vessel acts to maintain the output of the high-vacuum pump within a suitable pressure range. This removes the need for the output of the high-vacuum pump to be connected to a continuously operating, second-stage vacuum pump.

Abstract: A method of manufacturing a coil support member in which a thermosetting or thermoplastic material is introduced into a mould cavity and hardened, wherein one or more components are positioned within the mould cavity during the manufacturing process before the thermosetting or thermoplastic material is introduced, the components are then embedded in the thermosetting or thermoplastic material and form an integral part of the coil support member, and one or more functional filler materials are added to the thermosetting or thermoplastic material to improve the thermal matching between the integral components and the thermosetting or thermoplastic material.

Abstract: A method of estimating the environmental force acting on a supported jack-up vessel is described. The vessel is positioned in a force determination position and the strain on at least one support leg of the jack-up vessel is measured while a first thrust is applied to the vessel. A second thrust is applied to the vessel whilst the vessel is maintained in the force determination position. The variation in the strain in the at least one support leg is monitored as the second thrust is applied and the strain is used to calculate an estimate of the environmental force acting on the vessel. The method allows a dynamic positioning (DP) system of the jack-up vessel to determine a suitable thrust to apply to the vessel as the support legs of the vessel are raised. By applying this suitable thrust the position of the vessel can be maintained when the vessel transitions from being supported by the support legs to being supported by water.

Abstract: A rotating electrical machine comprises a rotor having an axis of rotation and a stator assembly surrounding the rotor. The stator assembly comprises a plurality of circumferentially arranged stator segments and a plurality of link elements of which at least one link element extends between each of the circumferentially adjacent stator segments. Each link element provides a rigid circumferential connection between circumferentially adjacent stator segments so that the linked stator segments form a torsionally stiff annular stator and also provides a radially flexible connection between circumferentially adjacent stator segments to permit relative movement between adjacent linked stator segments in the radial direction.

Abstract: An active magnetic bearing comprising a plurality of electromagnetic actuators, each actuator receiving for control thereof an input current and being able to exert a radial force on a shaft of a rotary machine, with respect to the rotation axis of said shaft, the shaft being able to be held without contact between the electromagnetic actuators and to undergo radial motion when it is in rotation, means for supplying input current of each actuator, the supply means comprising means for controlling the input current of each actuator, according to the position of the shaft with respect to the actuators. The supply means comprise means for damping the radial motion of the shaft.

Abstract: An offshore wind farm includes a plurality of wind turbines connected to an onshore converter station by means of a distributed power transmission system. The power transmission system includes a series of offshore converter platforms distributed within the wind farm. Each converter platform includes a busbar carrying an ac voltage for the converter platform and to which the wind turbines are connected. Each converter platform also includes one or more converter transformers connected to the busbar and a series of one or more converter modules. The power transmission system includes dc transmission lines which deliver generated power back to the onshore converter station.