Abstract: Diatom microbubblers comprising diatom biosilica or other silica linked to a catalyst for the decomposition of hydrogen peroxide, such as manganese oxide (MnO2), platinum (Pt), CuO (copper II oxide), or zinc peroxide (ZnO2) particles or nanosheets, or catalase are provided. Further provided are methods of reducing or eliminating biofilm or biofouling conditions.

Abstract: Provided is a method of controlling a permanent magnet generator, the method including: measuring mechanical noise of the generator; deriving two quantities indicative of an amplitude and a phase of an undesired harmonic of the measured noise; deriving, based on the quantities, a current to be injected in stator coils of the generator such as to reduce the undesired harmonic.

Abstract: Provided is a method of damping mechanical oscillations of plural wind turbines of a wind park commonly supplying electric energy to a grid, the method including: determining, for each of the plural wind turbines, a damping control signal for counteracting an oscillation of the respective wind turbine; supplying at least a subset of or a subset of modified versions of the damping control signals to respective wind turbines such that a sum of the supplied damping control signals is lower than a threshold.

Abstract: Provided is a control arrangement for controlling an electrical machine, including: a fundamental current controller, at least one harmonic flux controller related to a harmonic of an electrical frequency of the electrical machine, a summation system for adding voltage commands to obtain a summed voltage command based on which the electrical machine.

Abstract: Diatom microbubblers comprising diatom biosilica or other silica linked to a catalyst for the decomposition of hydrogen peroxide, such as manganese oxide (MnO2), platinum (Pt), CuO (copper II oxide), or zinc peroxide (ZnO2) particles or nanosheets, or catalase are provided. Further provided are methods of reducing or eliminating biofilm or biofouling conditions.

Abstract: Provided is a method of controlling a permanent magnet generator, the method including: measuring mechanical noise of the generator; deriving two quantities indicative of an amplitude and a phase of an undesired harmonic of the measured noise; deriving, based on the quantities, a current to be injected in stator coils of the generator such as to reduce the undesired harmonic.

Abstract: Provided is a control arrangement for controlling an electrical machine, including: a fundamental current controller, at least one harmonic flux controller related to a harmonic of an electrical frequency of the electrical machine, a summation system for adding voltage commands to obtain a summed voltage command based on which the electrical machine.

Abstract: A method, an arrangement and a computer program for controlling an energy flow to a grid, from an electrical alternating current machine with unbalanced impedance, in particular an electrical alternating current generator of a wind turbine, the method comprising: obtaining a first power signal representing a first power command.

Abstract: An arrangement for determining a d-component (Idref, I*d) of a reference current in a d-q coordinate system for reducing noise of a wind turbine, the arrangement including a noise/vibration determination module for determining noise/vibration components of oscillations of at least one wind turbine component, and a processing block for calculating a first type of the d-component of the reference current based on the noise/vibration component output by the noise/vibration determination module, is provided.

Abstract: A method to detect a decrease of the demagnetization of permanent magnets of the generator of a wind turbine, wherein a frequency converter is able to adapt to the variable frequency of the generator output voltage to the frequency of a power grid, wherein the AC/DC converter or the DC/AC converter of the frequency converter is been disabled, the electrical connections between the generator and the frequency converter are switched on via circuit breakers, the generator speed is determined; the generator output voltage is determined by a voltage sensor which is part of the frequency converter, the magnetic flux density of the generator is calculated depending on the generator speed and the generator output voltage, a demagnetization event is determined by comparing the resulting flux density value with a predetermined flux density value is provided.

Abstract: Provided is a method of damping mechanical oscillations of plural wind turbines of a wind park commonly supplying electric energy to a grid, the method including: determining, for each of the plural wind turbines, a damping control signal for counteracting an oscillation of the respective wind turbine; supplying at least a subset of or a subset of modified versions of the damping control signals to respective wind turbines such that a sum of the supplied damping control signals is lower than a threshold.

Abstract: A method and an apparatus for determining a phase and a frequency of an electric quantity being associated with an operation of an electrical device are described. The method comprises extracting a fundamental component of the electric quantity, calculating a positive sequence component of the electric quantity based on the extracted fundamental component, and determining the phase and the frequency of the electric quantity based on the calculated positive sequence component.

Abstract: A method to detect a decrease of the demagnetization of permanent magnets of the generator of a wind turbine, wherein a frequency converter is able to adapt to the variable frequency of the generator output voltage to the frequency of a power grid, wherein the AC/DC converter or the DC/AC converter of the frequency converter is been disabled, the electrical connections between the generator and the frequency converter are switched on via circuit breakers, the generator speed is determined; the generator output voltage is determined by a voltage sensor which is part of the frequency converter, the magnetic flux density of the generator is calculated depending on the generator speed and the generator output voltage, a demagnetization event is determined by comparing the resulting flux density value with a predetermined flux density value is provided.

Abstract: A method is provided for controlling a DC link voltage of a power converter connecting an electric generator of a wind turbine with a power grid. The method includes determining the rotational speed of a rotor of the electric generator. The method further includes determining a strength of harmonic components of the rotational speed of the rotor, wherein the harmonic components have frequency components being different from a fundamental rotational frequency of the electric generator. The method also includes determining a damping reference signal as a function of the determined strength of the harmonic components, and controlling the DC link voltage of the power converter in response to the determined damping reference signal. A corresponding control system is also provided.

Abstract: An arrangement for determining a d-component (Idref, I*d) of a reference current in a d-q coordinate system for reducing noise of a wind turbine, the arrangement including a noise/vibration determination module for determining noise/vibration components of oscillations of at least one wind turbine component, and a processing block for calculating a first type of the d-component of the reference current based on the noise/vibration component output by the noise/vibration determination module, is provided.

Abstract: A method, an arrangement and a computer program for controlling an energy flow to a grid, from an electrical alternating current machine with unbalanced impedance, in particular an electrical alternating current generator of a wind turbine, the method comprising: obtaining a first power signal representing a first power command.

Abstract: A method for controlling the operation of an electromechanical transducer is provided. The method includes (a) determining during a first period of time a first strength of the harmonic operational behavior of the transducer, (b) determining during a second period of time a second strength of the harmonic operational behavior of the transducer, wherein the second period of time is different from the first period of time, (c) calculating a harmonic control signal in response to both the determined first strength of the harmonic operational behavior and the determined second strength of the harmonic operational behavior, (d) generating a modified drive signal based on the calculated harmonic control signal, and (f) supplying the generated modified drive signal to electromagnetic coils of a stator of the transducer. Further, a corresponding control system for controlling the operation of an electromechanical transducer is provided.

Abstract: A method for controlling a power converter in a wind turbine generator, the power converter being connected to a power grid, the method comprising obtaining an alternating current (AC) line voltage at a connection point between the power converter and the power grid, obtaining a frequency of the power grid based on the AC line voltage, dynamically adapting the AC line voltage to the frequency of the power grid, generating a reference signal based on at least the frequency-adapted AC line voltage, and determining a converter control signal to be provided to the power converter based on the reference signal and the grid frequency in order to generate a power at the frequency of the power grid. Further, a wind turbine generator implementing the method is provided.

Abstract: A method and an apparatus for determining a phase and a frequency of an electric quantity being associated with an operation of an electrical device are described. The method comprises extracting a fundamental component of the electric quantity, calculating a positive sequence component of the electric quantity based on the extracted fundamental component, and determining the phase and the frequency of the electric quantity based on the calculated positive sequence component.

Abstract: A method for controlling a generator having a rotor with a plurality of magnets and a first stator winding and a second stator winding, electrically separate from the first stator winding is provided. The rotor rotates around a rotation axis perpendicular to a radial direction relative to the stator windings. The method includes allowing flow of a first electric current through the first stator winding, thereby generating a first radial force having a first magnitude and acting between the first stator winding and the rotor, and allowing flow of a second electric current through the second stator winding, thereby generating a second radial force having a second magnitude and acting between the second stator winding and the rotor, wherein the first magnitude is different from the second magnitude resulting in a net generator generated radial force generated by the first stator winding and the second stator winding at the rotor.