Abstract: A hybrid switch for a power converter and a method of operating said hybrid switch, the hybrid switch comprising: at a minimum a first and a second element comprising one or more switching devices of a first semiconductor type, and at a minimum a third element comprising one or more switching devices of a second semiconductor type, wherein the second semiconductor type is different from the first semiconductor type, and wherein each element is independently configurable and connected to a separate respective control terminal; and, a controller connected to the control terminals, wherein the controller is configured to control each element independently through each respective control terminal, and wherein the controller is further configured to activate elements based on a measured or estimated current and/or power as required by an operating condition of the converter.

Abstract: A method for islanding detection in an electrical power grid supplied by an electrical power source. The method includes measuring an output voltage (Vpcc) and a grid current (Ig) at an interconnection point of the power source with the power grid; estimating at least one grid parameter from the output voltage (Vpcc) and the grid current (Ig) based on optimizing a cost function, which minimizes a difference between the measured output voltage (Vpcc) and an estimated output voltage or a difference between the measured grid current (Ig) and an estimated grid current, which estimated output voltage or estimated output current is a function of the measured grid current (Ig) or the measured output voltage (Vpcc) and the least one estimated grid parameter; and detecting an islanding condition by detecting a jump and/or a deviation in the at least one estimated grid parameter.

Abstract: The present invention relates to a method of operating a wind farm comprising an upstream and a downstream turbine, wherein the upstream turbine is operated with current operation parameters under current wind conditions, wherein the method comprises the steps of: receiving future wind conditions for a time period for the wind farm, and evaluating required operation parameters for minimising wake effect of the downstream turbine under the future wind conditions, and determining a cost coefficient for changing the operation parameters to required operation parameters under consideration of fatigue effect of the wind turbine, calculating power productions P0 and Pc, in the predetermined time period, by the wind farm if operated with the current operation parameters under the current wind conditions and if operated with the required operation parameters under the future wind conditions, respectively, and operating the upstream turbine with the required operation parameters if the cost coefficient is lower than a

Abstract: The present invention is concerned with an operation of a wind farm with a plurality of wind turbines in view of a dynamic frequency response. According to the invention, dynamic frequency support and power production for all wind turbines in a wind farm are handled concurrently in a single optimization step and taking into account wake effects within the wind farm as well as optional wind forecast information. The dynamic frequency support capability of the entire wind farm is planned in advance according to grid requirements and power system condition changes. While existing methods de-load wind turbines with a static percentage in order to supply additional power when needed, the proposed method incorporates the dynamic frequency support into the optimal operation system of wind farm.

Abstract: An inverter system for a photovoltaic panel includes: an inverter adapted for transforming a DC voltage from the photovoltaic panel into an AC voltage to be supplied to an electrical grid; a DC link interconnected with the inverter and providing a positive DC link output connectable to a positive pole of the photovoltaic panel and a negative DC link output connectable to a negative pole of the photovoltaic panel; a switch for disconnecting the negative pole of the photovoltaic panel from the DC link; and a controller for controlling the inverter and the switch; wherein the controller is adapted for opening the switch, such that the photovoltaic panel is solely supplyable by the positive DC link output.

Abstract: A method for islanding detection in an electrical power grid supplied by an electrical power source. The method includes measuring an output voltage (Vpcc) and a grid current (Ig) at an interconnection point of the power source with the power grid; estimating at least one grid parameter from the output voltage (Vpcc) and the grid current (Ig) based on optimizing a cost function, which minimizes a difference between the measured output voltage (Vpcc) and an estimated output voltage or a difference between the measured grid current (Ig) and an estimated grid current, which estimated output voltage or estimated output current is a function of the measured grid current (Ig) or the measured output voltage (Vpcc) and the least one estimated grid parameter; and detecting an islanding condition by detecting a jump and/or a deviation in the at least one estimated grid parameter.

Abstract: A method for controlling a modular multi-level converter comprises the steps of: collecting control input variables from the converter; transmitting the control input variables to a controller of the converter via a first communication medium; determining, in the controller, and actual state of the converter and at least one control output variable based on a model of the converter; and transmitting the control output variable to the converter for controlling the converter via a second communication medium. The model of the converter accounts for the first and/or the second communication medium.

Abstract: A DC/AC converter is provided with a new control device and method for managing inrush current transients during operation without requiring additional external devices or emergency operating modes forcing the DC/AC converter to shut down. The present invention is particularly, but not exclusively, aimed at grid connected DC/AC, converters, often subject to inrush current phenomena due to perturbations in the grid.

Abstract: The present invention is concerned with an operation of a wind farm with a plurality of wind turbines in view of a dynamic frequency response. According to the invention, dynamic frequency support and power production for all wind turbines in a wind farm are handled concurrently in a single optimization step and taking into account wake effects within the wind farm as well as optional wind forecast information. The dynamic frequency support capability of the entire wind farm is planned in advance according to grid requirements and power system condition changes. While existing methods de-load wind turbines with a static percentage in order to supply additional power when needed, the proposed method incorporates the dynamic frequency support into the optimal operation system of wind farm.

Abstract: The present invention relates to a method of operating a wind farm comprising an upstream and a downstream turbine, wherein the upstream turbine is operated with current operation parameters under current wind conditions, wherein the method comprises the steps of: receiving future wind conditions for a time period for the wind farm, and evaluating required operation parameters for minimising wake effect of the downstream turbine under the future wind conditions, and determining a cost coefficient for changing the operation parameters to required operation parameters under consideration of fatigue effect of the wind turbine, calculating power productions Po and Pc, in the predetermined time period, by the wind farm if operated with the current operation parameters under the current wind conditions and if operated with the required operation parameters under the future wind conditions, respectively, and operating the upstream turbine with the required operation parameters if the cost coefficient is lower than a

Abstract: DC/AC converter comprising a new control device and method for managing inrush current transients during operation without requiring additional external devices or emergency operating modes forcing the DC/AC converter to shut down. The present invention is particularly, but not exclusively, aimed at grid connected DC/AC, converters, often subject to inrush current phenomena due to perturbations in the grid.

Abstract: A method for controlling a modular multi-level converter comprises the steps of: collecting control input variables from the converter; transmitting the control input variables to a controller of the converter via a first communication medium; determining, in the controller, and actual state of the converter and at least one control output variable based on a model of the converter; and transmitting the control output variable to the converter for controlling the converter via a second communication medium. The model of the converter accounts for the first and/or the second communication medium.

Abstract: In a method based on the MPDTC algorithm for controlling an inverter of an electrical system, the harmonics and resonances in the inverter can be damped by extracting frequency information from predicted data of the MPDTC algorithm and by damping harmonic distortion of the electrical system by reintroducing the extracted frequency information into a control loop of the inverter.

Abstract: In a method based on the MPDTC algorithm for controlling an inverter of an electrical system, the harmonics and resonances in the inverter can be damped by extracting frequency information from predicted data of the MPDTC algorithm and by damping harmonic distortion of the electrical system by reintroducing the extracted frequency information into a control loop of the inverter.

Abstract: Registering a sheet in a differential drive registration system by identifying observed state values corresponding to a sheet handled by the differential drive registration system. The method also including determining an error vector, wherein the error vector is defined by a difference between the observed state values and reference state values for the sheet. Control input values are also determined based on the error vector, a set of control parameters, and the observed state values. The control input values being determined such that there is a linear differential relationship between the observed state values and the control input values. Additionally the method includes generating drive wheel velocities in the differential drive registration system based on the control input values. The identifying and determining steps being repeated for the sheet in a closed-loop process such that the observed state values substantially track the reference state values.

Abstract: Registering a sheet in a differential drive registration system by identifying observed state values corresponding to a sheet handled by the differential drive registration system. The method also including determining an error vector, wherein the error vector is defined by a difference between the observed state values and reference state values for the sheet. Control input values are also determined based on the error vector, a set of control parameters, and the observed state values. The control input values being determined such that there is a linear differential relationship between the observed state values and the control input values. Additionally the method includes generating drive wheel velocities in the differential drive registration system based on the control input values. The identifying and determining steps being repeated for the sheet in a closed-loop process such that the observed state values substantially track the reference state values.