Abstract: A method of controlling a combined plant to provide frequency support to a power grid operating at a variable grid frequency, wherein the combined plant includes at least one generator and an energy store, and the combined plant is adapted to supply power to the power grid, the method including the steps of charging the energy store at less than its rated power when frequency support is not needed. When frequency support is needed the combined plant is controlled to increase or decrease the overall power that it supplies to the power grid to provide frequency support. The control of the combined plant can be designed to maximize frequency support revenues.

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.

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 method of controlling a combined plant to provide frequency support to a power grid operating at a variable grid frequency, wherein the combined plant includes at least one generator and an energy store, and the combined plant is adapted to supply power to the power grid, the method including the steps of charging the energy store at less than its rated power when frequency support is not needed. When frequency support is needed the combined plant is controlled to increase or decrease the overall power that it supplies to the power grid to provide frequency support. The control of the combined plant can be designed to maximize frequency support revenues.

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: 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.

Abstract: Various computer-implemented methods for classifying defects on a specimen are provided. One method includes assigning individual defects detected on the specimen to defect groups based on one or more characteristics of the individual defects. The method also includes displaying information about the defect groups to a user. In addition, the method includes allowing the user to assign a classification to each of the defect groups. Systems configured to classify defects on a specimen are also provided. One system includes program instructions executable on a processor for assigning individual defects detected on the specimen to defect groups based on one or more characteristics of the individual defects. The system also includes a user interface configured for displaying information about the defect groups to a user and allowing the user to assign a classification to each of the defect groups.

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 minimises 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 as shown in graph (c). 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: Various computer-implemented methods for classifying defects on a specimen are provided. One method includes assigning individual defects detected on the specimen to defect groups based on one or more characteristics of the individual defects. The method also includes displaying information about the defect groups to a user. In addition, the method includes allowing the user to assign a classification to each of the defect groups. Systems configured to classify defects on a specimen are also provided. One system includes program instructions executable on a processor for assigning individual defects detected on the specimen to defect groups based on one or more characteristics of the individual defects. The system also includes a user interface configured for displaying information about the defect groups to a user and allowing the user to assign a classification to each of the defect groups.