Abstract: A method for damping power oscillation in an electric power grid, comprising: performing a procedure for determination of a phase shift between a filtered voltage signal and a filtered frequency signal; based on the performed procedure, determining which one of the filtered voltage signal and filtered frequency signal is leading or lagging in relation to the other one of the filtered voltage signal and filtered frequency signal; based on the determination of which one of the filtered voltage signal and filtered frequency signal is leading or lagging, setting a gain of a power oscillation damping controller to be positive or negative; applying the power oscillation damping controller with the set gain so as to produce an output signal outputted from the power oscillation damping controller; and based on the produced output signal, controlling an injection of electric power to the grid so as to dampen power oscillation in the grid.

Abstract: The invention relates to wind turbines, particularly to controlling reactive power exchange between a power grid and a wind power plant. The wind power plant has a plurality of wind turbine generators each having a corresponding power converter with a converter controller. Further, the wind power plant has a power plant transformer with an on load tap changer coupled between the wind power plant and the power grid. The power plant controller is regulating the on load tap changer and is generating reactive component setpoints for the wind turbine generators, when determining a need for production of short-term reactive power due to a sudden change in reactive power measured at the point of common coupling.

Abstract: Limiting generator loads in a wind turbine having a power converter with a line side inverter configured as a grid forming inverter. A maximum grid current value is determined based on a measured generator load and a limit function. A virtual impedance value and a virtual voltage drop over the virtual impedance value are determined. A virtual synchronous machine angle is determined based on a power reference and the virtual grid power. The voltage reference for controlling the line side inverter is determined based on the virtual synchronous machine angle, the virtual voltage drop and the voltage magnitude reference.

Abstract: The present invention relates to a direct alcohol fuel cell comprising a housing containing a proton exchange membrane (PEM) separating an anode section from a cathode section, which anode section and which cathode section are contained in the housing, the cathode section comprising a cathode collection element electrically connected to a cathode catalyst, which cathode catalyst is in diffusive communication with a gaseous oxidant, and the anode section comprising an anode collection element electrically connected to an anode catalyst, and a pervaporation membrane located at a spacing distance from the PEM, which pervaporation membrane provides diffusive communication between the anode catalyst and a fuel supply, wherein the housing comprises one or more venting holes providing fluid communication between the anode section and the ambient environment, which venting hole has or which venting holes have a largest dimension in the range of 25 ?m to 300 ?m, the venting hole being located within the spacing distan

Abstract: The present invention relates to a direct alcohol fuel cell (DAFC) comprising an anode terminal electrically connected to an anode catalyst in fluid communication with a fuel supply; a cathode catalyst in fluid communication with a gaseous oxidant; an electrically conducting cathode plate having a collecting element with evaporation holes, a bendable segment and a terminal site, which collecting element is electrically connected to the cathode catalyst; and a housing containing the collecting element, and a proton exchange membrane (PEM) between the anode catalyst and the cathode catalyst.

Abstract: Aspects of the present invention relate to a method for reducing high torque levels and/or high rates of change of torque in a wind turbine generator that comprises a machine-side converter and a line-side converter connected by a DC link, and, wherein the line-side converter is operated according to a virtual synchronous machine control scheme. The method comprises: determining a generator torque; determining a torque surplus indicating the amount that the generator torque exceeds a torque limit; determining an active power surplus corresponding to the torque surplus; controlling the line-side converter according to the virtual synchronous machine control scheme using an input parameter configured to reduce the active power output of the line side converter by the active power surplus.

Abstract: The invention relates to a method for controlling a power generating unit. The method includes determining a virtual impedance value, determining a virtual grid power based on the virtual resistance value and the grid current, determining a virtual synchronous machine rotational speed and/or a synchronous machine angle of a virtual synchronous generator, and determining a voltage reference for controlling a line side converter to generate the desired reactive power based on the virtual synchronous machine rotational speed or angle, a virtual voltage and the voltage magnitude reference.

Abstract: The invention relates to a method for controlling power generation of a VSM wind turbine. The wind turbine comprises a machine side converter, a line side converter, a DC link, and an electric storage device electrically connected to the DC link. The method comprises determining a first power control signal to the machine side converter, determining a second power control signal for controlling a desired output power of the line side converter based on a storage device voltage error, and a power production reference, and determining a charging current reference for controlling charging and discharging of the electric storage device based on a DC-link voltage error.

Abstract: The present invention relates to a direct alcohol fuel cell comprising a housing containing a proton exchange membrane (PEM) separating an anode section from a cathode section, which anode section and which cathode section are contained in the housing, the cathode section comprising a cathode collection element having one or more ventilation holes, which cathode collection element is electrically connected to a cathode catalyst, which cathode catalyst is in diffusive communication with a gaseous oxidant, and the anode section comprising an anode collection element electrically connected to an anode catalyst, the DAFC comprising an oleophobic filter covering the ventilation hole(s). The oleophobic filter may be held in place using any appropriate means as desired. The fuel cell is suited for a microelectronic device.

Abstract: Controlling a current injected to a power grid from a renewable power plant, in response to a voltage event in the power grid. At least a current at a point of common coupling between the renewable power plant and the power grid is determined and provided to a power plant controller (PPC). The PPC derives individual current setpoint corrections for at least some wind turbines, based on the determined current, and dispatches each derived current setpoint correction to wind turbine controllers of the corresponding wind turbines. The wind turbine controllers control a current output of the respective wind turbines, based on measurements of current and/or voltage at a point of connection between the wind turbine and an internal grid of the renewable power plant, and by taking into account the dispatched current setpoint correction.

Abstract: A method for controlling one or more renewable power generators forming a renewable power plant, and a controller configured to perform the method. In one aspect, plant voltage control is carried out on the basis of a more accurate voltage-reactive power relationship value which is determined dynamically based on grid conditions rather than the conventional approach of the voltage-reactive power relationship being a static value that is based on information provided by a transmission system operator during installation or commissioning of the power plant.

Abstract: The invention relates to a method for damping drive train oscillations of a VSM configured wind turbine. The method comprises determining a drive train damping power signal based on speed signal representing a generator speed, determining a power deviation based on a combination of a power reference for a desired power production, the drive train damping power-signal, a grid power supplied by the line side converter to the grid and a damping power, determining a virtual synchronous machine angle based on the power deviation so that the derivative of the virtual synchronous machine rotational speed is indicative of the power deviation, determining a converter reference for controlling the line side converter to generate the desired active power based on the virtual synchronous machine angle and a voltage reference for a voltage amplitude to be generated by the line side converter, and applying the converter reference to the line side converter.

Abstract: The invention relates to a method for controlling a wind turbine as virtual synchronous machine by determining the synchronous machine rotational speed rotational speed and the synchronous machine angle. The virtual synchronous machine rotational speed is determined based on a combination of a feedback of a damping power, a power reference for a desired power output of the wind turbine, a grid power supplied by the wind turbine to a power grid and a chopper power dissipated by the chopper and an inertial integration model, the synchronous machine angle is determined based on an integration of the synchronous machine rotational speed, and the damping power is determined based on the virtual synchronous machine rotational speed.

Abstract: The invention relates to wind turbines, particularly to controlling reactive power exchange between a power grid and a wind power plant. The wind power plant has a plurality of wind turbine generators each having a corresponding power converter with a converter controller. Further, the wind power plant has a power plant transformer with an on load tap changer coupled between the wind power plant and the power grid. The power plant controller is regulating the on load tap changer and is generating reactive component setpoints for the wind turbine generators, when determining a need for production of short-term reactive power due to a sudden change in reactive power measured at the point of common coupling.

Abstract: Aspects of the present invention relate to a method of voltage control for at least one wind turbine generator configured to absorb and supply reactive power on demand, the method comprises: receiving a dispatch signal from a power plant controller indicating a reactive power set point; determining a terminal voltage level of the at least one wind turbine generator; generating a reactive power correction value based on a deviation of the terminal voltage level from a voltage set point; adjusting the reactive power set point by the reactive power correction value; and controlling the at least one wind turbine generator according to the adjusted reactive power set point.

Abstract: The invention relates to a method for controlling a power generating unit. The method includes determining a virtual impedance value, determining a virtual grid power based on the virtual resistance value and the grid current, determining a virtual synchronous machine rotational speed and/or a synchronous machine angle of a virtual synchronous generator, and determining a voltage reference for controlling a line side converter to generate the desired reactive power based on the virtual synchronous machine rotational speed or angle, a virtual voltage and the voltage magnitude reference.

Abstract: Embodiments provide for the control of a power plant including several generators by setting a reference frame for the generators with a first and a second axis; measuring a grid demand voltage at the shared connection point; determining active and reactive currents required at the shared connection point based on the grid demand voltage and grid codes; transforming the active and reactive currents required at the shared connection point to the reference frame where the first axis defines a first current set point and the second axis defines a second current set point; and dispatching the first and second current set points to generator controllers associated with each generator. Current set points may be generated for positive/negative frames, direct quadrature frames, real/imaginary frames and may be set evenly for all generators or adjusted per generator.

Abstract: A grid side inverter system includes a grid side inverter, a phase locked loop controller arranged to determine a phase of a dq-frame dependent on a monitored grid voltage vector in the dq-frame and a reference grid voltage vector in the dq-frame, a current reference decision unit arranged to generate a reduction of at least one of an active and a reactive current reference, wherein a decision to generate the reduction is based on an electrical parameter relating to the phase difference of the monitored grid voltage vector and the PLL vector, a current controller arranged to determine control signals for the grid side inverter for controlling generation of active and reactive power to the grid dependent on the active and reactive current references and monitored active and a reactive grid currents in the dq-frame.

Abstract: Aspects of the present invention relate to a method for reducing high torque levels and/or high rates of change of torque in a wind turbine generator that comprises a machine-side converter and a line-side converter connected by a DC link, and, wherein the line-side converter is operated according to a virtual synchronous machine control scheme. The method comprises: determining a generator torque; determining a torque surplus indicating the amount that the generator torque exceeds a torque limit; determining an active power surplus corresponding to the torque surplus; controlling the line-side converter according to the virtual synchronous machine control scheme using an input parameter configured to reduce the active power output of the line side converter by the active power surplus.

Abstract: A method for controlling one or more renewable power generators forming a renewable power plant, and a controller configured to perform the method. In one aspect, plant voltage control is carried out on the basis of a more accurate voltage-reactive power relationship value which is determined dynamically based on grid conditions rather than the conventional approach of the voltage-reactive power relationship being a static value that is based on information provided by a transmission system operator during installation or commissioning of the power plant.