Provided is a method for controlling, by means of field-oriented closed-loop control, an active rectifier which is electrically connected to a stator of a generator of a wind turbine. The generator has a rotor which is mounted so as to be rotatable about the stator and comprises the steps of determining a mechanical position of the rotor with respect to the stator, predefining DC components of rotor-fixed d and q coordinates for at least one 3-phase stator current, determining an AC component for the q coordinate at least as a function of the mechanical position of the rotor, modulating the determined AC component of the q coordinate onto the predefined DC component of the q coordinate, so that a modulated q coordinate is produced which has a DC component and an AC component, and controlling the active rectifier at least as a function of the modulated q coordinate and preferably as a function of the d coordinate.

Systems and methods for generating electricity from a fluid turbine are provided. In one aspect, the system employs a Tesla turbine to rotate a drive shaft, the drive shaft providing torque to operate an electrical generator. The incoming fluid flow that operates the Tesla turbine enters a hollow portion of the drive shaft and exists the system as an exhaust flow. The system may operate from standard water supplies provided to a residence or business, thereby reclaiming excess water pressure energy.

The present invention relates to a wind turbine with an electrical machine wherein said electrical machine comprises a stator (702) with one or more electrical winding(s) (704), said electrical winding(s) being arranged to be connected to an electrical grid (760) by at least one cable (740) with at least one phase conductor (746), the at least one cable (740) comprises at least one return path (744) to conduct leakage currents, and at least one electrical shield (745), the stator being electrically isolated from a stator housing (701). The invention also relates to a method for minimizing stray currents in an electrical machine in a wind turbine.

An energy harvester for use in-line with a pipe to harness potential and kinetic energy of fluids flowing therein. Structure for the energy harvester may include a shaft and a blade extending radially therefrom. The shaft can penetrate a housing that operates as a pipe section to install the device in-line with pipe. The shaft can couple with an electrical generator. A load may connect with voltage terminals on the generator so that fluid impinging on the blades will rotate the generator to power the load, effectively harvesting power from the flowing fluid. In one implementation, a load control device that couples with the generator voltage terminals controls a pressure characteristic of the fluid, such as pressure drop, by applying an electrical load on the generator and controllably impeding rotation of the shaft.

A turboexpander can operate as a microgrid electric generator for islanding operations. The turboexpander can recover energy lost during a pressure letdown sequence to generate electricity. Pressurized process gas can cause a turbine to rotate, thereby rotating a rotor within a stator of the turboexpander. A power electronics can include an islanding mode inverter to output an alternating current that comprises a frequency and an amplitude compatible with powering a load. The power electronics can include a battery that is charged by the turboexpander and can provide power for starting up the turboexpander. The power electrics can include a bidirectional inverter to send excess power from the turboexpander to a power grid and to receive power from the power grid for start-up.

Three controls, three variable gear assemblies, an optional hatch or variable propeller pitch, and a variable overlap generator (VO generator), as well as one or more commutator and brush-less free direct current generators may be used independently and together to provide constant frequency and voltage output power and to increase the amount of output power generated with the same input water flow or wind speed in a plurality of embodiments useful in wind power generation and water renewable energy generators for any of tidal and ocean current or wave conditions. Two Transgear assemblies side-by-side and sharing the same central shaft may comprise a constant speed motor control, produce required constant frequency and voltage and be reduced in part count and complexity. The variable overlap generator of a marine hydrokinetic or wind power generator may be used as a low torque generator, a high power-rated generator or a control in these applications and may generate more electric power than a conventional fixed power generator (the rotor axially aligned to overlap the stator in a conventional manner) over a wider input range. An electromotive force (EMF) embodiment generates alternating current at constant frequency and voltage in varying wind and water speed conditions.

A method for controlling a windfarm having a plurality of wind power installations and feeding into an electrical supply network at a network connection point is provided. The method includes inputting at least one control error at a control error input of a windfarm control module, generating at least one manipulated variable depending on the at least one control error using at least one controller, and outputting the at least one manipulated variable at a manipulated variable output for transmission to the wind power installations. The method includes recording in each case at least one state of the windfarm, the windpower installations thereof and/or an ambient condition as form state at a state input of the control module, and altering or predefining at least one property of the at least one controller depending on the at least one recorded form state by means of a controller setting device.

A drone with its own power generating function is introduced. The drone includes a central body, a battery attached to the bottom of the central body, multiple arms extended from the central body radially, drive rotors to be fitted on the top of the arms, a ring-shaped subsidiary guide positioned below the arms and supported by the multiple arms and multiple 1st generators arranged in parallel to the drive rotors on the subsidiary guide

A turboexpander can operate as a microgrid electric generator for islanding operations. The turboexpander can recover energy lost during a pressure letdown sequence to generate electricity. Pressurized process gas can cause a turbine to rotate, thereby rotating a rotor within a stator of the turboexpander. A power electronics can include an islanding mode inverter to output an alternating current that comprises a frequency and an amplitude compatible with powering a load. The power electronics can include a battery that is charged by the turboexpander and can provide power for starting up the turboexpander. The power electrics can include a bidirectional inverter to send excess power from the turboexpander to a power grid and to receive power from the power grid for start-up.

An energy harvester for use in-line with a pipe to harness potential and kinetic energy of fluids flowing therein. Structure for the energy harvester may include a shaft and a blade extending radially therefrom. The shaft can penetrate a housing that operates as a pipe section to install the device in-line with pipe. The shaft can couple with an electrical generator. A load may connect with voltage terminals on the generator so that fluid impinging on the blades will rotate the generator to power the load, effectively harvesting power from the flowing fluid. In one implementation, a load control device that couples with the generator voltage terminals controls a pressure characteristic of the fluid, such as pressure drop, by applying an electrical load on the generator and controllably impeding rotation of the shaft.