Abstract: A method for controlling the operation of a wind turbine which includes a mechanical drive train, an electric generator being mechanically connected to the drive train, and a power converter being electrically connected to the generator is provided. The method comprises (a) determining a frequency of an AC output voltage signal provided by the power converter; (b) recognizing, whether there has been a modification of the determined frequency with respect to a previously determined frequency, which modification is larger than a given threshold; (c) if the modification of the determined frequency is larger than the given threshold, changing a power reference signal for the wind turbine; (d) providing the changed power reference signal to a controller of the wind turbine; and (e) controlling the operation of the wind turbine on the basis of the changed power reference signal.

Abstract: A self-commutated converter is connected to further self-commutated converters by its AC voltage connection via an inductive component using a coupling point, which is common to all the converters, in an AC voltage network. An active power P and a frequency fN are determined from a network voltage at the coupling point and a converter current flowing via the inductive component. A active power difference value ?P is supplied to an orthogonal controller and to a parallel controller. The output value from the parallel controller is used to minimize the reactive power exchanged between converter and coupling point. The frequency difference value ?f is supplied to a frequency controller and the output value from the frequency controller is logically combined with the output value from the orthogonal controller and the output value from the parallel controller, the frequency difference value ?f being simultaneously minimized.

Abstract: A controller is provided for controlling a power converter that converts electrical input power of a wind turbine into electrical output power provided to a grid. The power converter includes grid-side and turbine-side converter parts. The controller comprises an input terminal for receiving a voltage reference signal associated with a predefined grid voltage and a frequency reference signal associated with a predefined grid frequency, and a network bridge controller adapted to control power conversion of the grid-side converter part. The network bridge controller includes a modulator for modulating gate drive command signals in the grid-side converter part based on a reference voltage and a reference angle derived from the voltage reference signal and the frequency reference signal. The modulator is adapted to modulate the gate drive command signals to maintain the predefined grid voltage and the predefined grid frequency in the power converter in case of failure within the grid.

Abstract: A power supply arrangement adapted to provide auxiliary power to a wind farm that feeds into a HVDC transmission link is provided. The power supply arrangement has an auxiliary power supply to deliver auxiliary power (Paux) to the wind farm; a backfeed control for initiating provision of a backfeed voltage on the HVDC link during a wind farm downtime; a backfeed switch to close a DC current path between the HVDC link and the auxiliary power supply; and a power converter for converting the backfeed voltage into auxiliary power (Paux). A wind farm arranged to feed into a HVDC transmission link is also provided, having such a power supply arrangement for providing auxiliary power (Paux) to the wind farm during a wind farm downtime. A method of providing auxiliary power (Pbackfeed) to a wind farm during a wind farm downtime is also provided.

Abstract: A disturbance on an electric signal at an electric connection between an electric power generating system and a power grid is decomposed into a first disturbance with a first strength assigned to the electric power generating system and a second disturbance with a second strength assigned to the power grid. A voltage value of a voltage of the electric signal is measured. A current value of a current of the electric signal is measured. A value of an open circuit voltage of an equivalent voltage source is calculated based on the measured voltage value, the measured current value and a characteristic equivalent impedance of the electric power generating system so that the electric power generating system is in a harmonic model. The strength of the first disturbance is determined based on the calculated value of the open circuit voltage of the equivalent voltage source.

Abstract: A current controller device using a vector control algorithm for controlling conversion of DC power into AC power is provided. The controller device has an open loop control loop gain and produces a first and a second voltage demand signals based on a first and a second current demand signals, a first and a second current feedback signals, a first and a second voltage feedback signals. The open loop control loop gain depends on frequencies of the first and second current feedback signals. A first and a second filters are provided at a first and a second current feedback inputs respectively. The first and second filters each have a filter characteristics to reduce the frequencies of the first and second current feedback signals at which the open loop control loop gain is greater than unity and has a phase less than or equal to minus 180°.

Abstract: A controller is provided for controlling a power converter that converts electrical input power of a wind turbine into electrical output power provided to a grid. The power converter includes grid-side and turbine-side converter parts. The controller comprises an input terminal for receiving a voltage reference signal associated with a predefined grid voltage and a frequency reference signal associated with a predefined grid frequency, and a network bridge controller adapted to control power conversion of the grid-side converter part. The network bridge controller includes a modulator for modulating gate drive command signals in the grid-side converter part based on a reference voltage and a reference angle derived from the voltage reference signal and the frequency reference signal. The modulator is adapted to modulate the gate drive command signals to maintain the predefined grid voltage and the predefined grid frequency in the power converter in case of failure within the grid.

Abstract: A disturbance on an electric signal at an electric connection between an electric power generating system and a power grid is decomposed into a first disturbance with a first strength assigned to the electric power generating system and a second disturbance with a second strength assigned to the power grid. A voltage value of a voltage of the electric signal is measured. A current value of a current of the electric signal is measured. A value of an open circuit voltage of an equivalent voltage source is calculated based on the measured voltage value, the measured current value and a characteristic equivalent impedance of the electric power generating system so that the electric power generating system is in a harmonic model. The strength of the first disturbance is determined based on the calculated value of the open circuit voltage of the equivalent voltage source.

Abstract: A full converter connected to a series compensated transmission line. The full converter comprises a generator side converter, a DC link connected across an output of the generator side converter, a line side converter connected across an output of the DC link, and a converter controller configured to control the full converter to mitigate effects of subsynchronous oscillations present on the series compensated transmission line.

Abstract: A full converter connected to a series compensated transmission line. The full converter comprises a generator side converter, a DC link connected across an output of the generator side converter, a line side converter connected across an output of the DC link, and a converter controller configured to control the full converter to mitigate effects of subsynchronous oscillations present on the series compensated transmission line.

Abstract: There is provided a controller for a converter and a respective method of operating such a controller. The converter receives an input power and provides an output power by a switching operation wherein in an embodiment the output power has at least two phases. The controller includes an input for receiving a feedback signal depending on the output power of the converter, and an output for providing a control signal to the converter to thereby control the switching operation of the converter. The control signal corresponds to a switching pattern that is updated in response to the feedback signal. The control signal includes a harmonic compensation signal which reduces higher harmonics in the output power, the higher harmonics originating from a time delay between taking the feedback signal and the updating of the switching pattern.

Abstract: A current controller device using a vector control algorithm for controlling conversion of DC power into AC power is provided. The controller device has an open loop control loop gain and produces a first and a second voltage demand signals based on a first and a second current demand signals, a first and a second current feedback signals, a first and a second voltage feedback signals. The open loop control loop gain depends on frequencies of the first and second current feedback signals. A first and a second filters are provided at a first and a second current feedback inputs respectively. The first and second filters each have a filter characteristics to reduce the frequencies of the first and second current feedback signals at which the open loop control loop gain is greater than unity and has a phase less than or equal to minus 180°.

Abstract: The present invention provides a power converter that can be used to interface a generator (4) that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency and including features that allow the power converter to remain connected to the supply network and retain control during supply network fault and transient conditions. The power converter includes a generator bridge (10) electrically connected to the stator of the generator (4) and a network bridge (14). A dc link (12) is connected between the generator bridge (10) and the network bridge (14). A filter (16) having network terminals is connected between the network bridge (14) and the supply network. A first controller (18) is provided for controlling the operation of the semiconductor power switching devices of the generator bridge (14).

Abstract: The present invention provides a power converter that can be used to interface a generator (4) that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency and including features that allow the power converter to remain connected to the supply network and retain control during supply network fault and transient conditions. The power converter includes a generator bridge (10) electrically connected to the stator of the generator (4) and a network bridge (14). A dc link (12) is connected between the generator bridge (10) and the network bridge (14). A filter (16) having network terminals is connected between the network bridge (14) and the supply network. A first controller (18) is provided for controlling the operation of the semiconductor power switching devices of the generator bridge (14).

Abstract: The present invention provides a power converter that can be used to interface a generator (4) that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency and including features that allow the power converter to remain connected to the supply network and retain control during supply network fault and transient conditions. The power converter includes a generator bridge (10) electrically connected to the stator of the generator (4) and a network bridge (14). A dc link (12) is connected between the generator bridge (10) and the network bridge (14). A filter (16) having network terminals is connected between the network bridge (14) and the supply network. A first controller (18) is provided for controlling the operation of the semiconductor power switching devices of the generator bridge (14).

Abstract: The present invention provides a power converter that can be used to interface a generator (4) that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency and including features that allow the power converter to remain connected to the supply network and retain control during supply network fault and transient conditions. The power converter includes a generator bridge (10) electrically connected to the stator of the generator (4) and a network bridge (14). A dc link (12) is connected between the generator bridge (10) and the network bridge (14). A filter (16) having network terminals is connected between the network bridge (14) and the supply network. A first controller (18) is provided for controlling the operation of the semiconductor power switching devices of the generator bridge (14).

Abstract: The present invention provides a power converter that can be used to interface a generator (4) that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency and including features that allow the power converter to remain connected to the supply network and retain control during supply network fault and transient conditions. The power converter includes a generator bridge (10) electrically connected to the stator of the generator (4) and a network bridge (14). A dc link (12) is connected between the generator bridge (10) and the network bridge (14). A filter (16) having network terminals is connected between the network bridge (14) and the supply network. A first controller (18) is provided for controlling the operation of the semiconductor power switching devices of the generator bridge (14).

Abstract: The present invention provides a power converter that can be used to interface a generator (4) that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency and including features that allow the power converter to remain connected to the supply network and retain control during supply network fault and transient conditions. The power converter includes a generator bridge (10) electrically connected to the stator of the generator (4) and a network bridge (14). A dc link (12) is connected between the generator bridge (10) and the network bridge (14). A filter (16) having network terminals is connected between the network bridge (14) and the supply network. A first controller (18) is provided for controlling the operation of the semiconductor power switching devices of the generator bridge (14).

Abstract: The present invention provides_a power converter that can be used to interface a generator (4) that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency and including features that allow the power converter to remain connected to the supply network and retain control during supply network fault and transient conditions. The power converter includes a generator bridge (10) electrically connected to the stator of the generator (4) and a network bridge (14). A dc link (12) is connected between the generator bridge (10) and the network bridge (14). A filter (16) having network terminals is connected between the network bridge (14) and the supply network. A first controller (18) is provided for controlling the operation of the semiconductor power switching devices of the generator bridge (14).

Abstract: The present invention provides a power converter that can be used to interface a generator that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency and including features that allow the power converter to remain connected to the supply network and retain control during supply network fault and transient conditions. The power converter includes a generator bridge electrically connected to the stator of the generator and a network bridge. A dc link is connected between the generator bridge and the network bridge. A filter having network terminals is connected between the network bridge and the supply network. A first controller is provided for controlling the operation of the semiconductor power switching devices of the generator bridge. Similarly, a second controller is provided for controlling the operation of the semiconductor power switching devices of the network bridge.