The invention relates to a method for operating a wind turbine which comprises a power generator, a generator side converter, a grid side converter, a DC link electrically connected to an output of the generator side converter and an input of the grid side converter. The method comprises monitoring a wind turbine signal for detection of an operational condition which requires an increase of an output voltage of the grid side converter, upon detection of the operational condition, initiate an over-modulation mode wherein the grid side converter is operated with a modulation index in an over-modulation range, and upon the detection of the operational condition, initiate a DC-voltage adjustment mode wherein the a DC-voltage of the DC link is increased from a first voltage level towards a second voltage level.

A method of controlling an induction generator is provided connected to a utility grid, the method including: receiving an actual grid frequency; and controlling rotor windings of the generator by a rotor control signal having a rotor winding reference frequency being set in dependence of the actual grid frequency.

An arrangement contains an asynchronous machine having a rotor and a stator. The arrangement is set up in a generator mode for feeding electrical energy into an AC voltage network. The arrangement is characterized in that the asynchronous machine can be doubly fed. The asynchronous machine can be connected in a matrix configuration to the AC voltage network by a modular multi-level converter, and the modular multi-level converter is set up in a motor mode of the arrangement for starting up the asynchronous machine while short-circuiting the rotor or the stator.

The present disclosure relates to methods (300) to determine a duration of a period for warming up of a power converter (20) of a wind turbine (1). The method (300) comprises determining (301) a first indicator that is indicative of a time that the power converter (20) has been inactive. Further, the method (300) comprises determining (302) the period for warming up at least partially based on the first indicator. A power converter assembly is also disclosed.

A method for controlling an inverter-based resource having a power converter connected to an electrical grid includes receiving, via a regulator of a controller of the inverter-based resource, a plurality of power signals. The method also includes determining, via the regulator, a power error signal as a function of the plurality of power signals. Further, the method includes receiving, via the regulator, a dynamic multiplier factor from a supervisory controller. Moreover, the method includes applying, via the regulator, the dynamic multiplier factor to one or more gains of the regulator to determine one or more modified gains. In addition, the method includes applying the one or more modified gains to the power error signal to obtain an intermediate power signal. Thus, the method includes generating, via the regulator, one or more control commands for the power converter as a function of the intermediate power signal.

The system and method described herein provide control for a power generating asset having a double-fed generator connected to an electrical grid. Accordingly, a non-deliverable component and a deliverable component of a total power output of a generator of the power generating asset is determined via a controller. A compensation module of the controller then determines a first control signal based, at least in part, on the non-deliverable component. The first control signal is configured to establish a modified rotor current setpoint. Additionally, a buffer module of the controller then determines a buffer control signal for a DC energy buffer based, at least in part, on the non-deliverable component. The DC energy buffer is operably coupled between a line-side converter and a rotor-side converter of a power converter of the power generating asset. In response to the first control signal and the buffer control signal the non-deliverable component is delivered to the DC energy buffer via the line-side converter, thereby precluding the delivery of the non-deliverable component to or from the electrical grid. The deliverable component of the total power output of the generator is delivered to the electrical grid.

A wind turbine electrical power generating system includes a first generator configured to be mechanically coupled to a rotor, a second generator configured to be mechanically coupled to the rotor; and an electrical power conversion system including at least a first and a second power converter section. The first power converter section is electrically coupled between a rotor winding of the first generator and a coupling point and a stator winding of the first generator is electrically coupled to the coupling point such that only a fraction of electrical power generated by the first generator passes through the power conversion system. The second power converter section is electrically coupled between an electrical power output of the second generator and the coupling point such that the electrical power provided by the second generator to the coupling point passes through the power conversion system.

The system and method described herein provide grid-forming control of a power generating asset having a double-fed generator connected to a power grid. Accordingly, a stator-frequency error is determined for the generator. The components of the stator frequency error are identified as a torsional component corresponding to a drivetrain torsional vibration frequency and a stator component. Based on the stator component, a power output requirement for the generator is determined. This power output requirement is combined with the damping power command to develop a consolidated power requirement for the generator. Based on the consolidated power requirement, at least one control command for the generator is determined and an operating state of the generator is altered.

A method for controlling a wind turbine system connected to a power grid. The method comprises generating a wind turbine control signal based on a power control reference for controlling a power output of a wind turbine; monitoring an electrical frequency of the power grid; in response to detecting a change in the frequency in the power grid, activating a fast frequency support method comprising the steps of; adjusting the power control reference to cause an overproduction of power by the wind turbine; the overproduction of power causing a transfer of inertial kinetic energy from the wind turbine to electrical power; wherein the power control reference is determined by applying an adaptive gain function to a measurement of a difference in grid frequency from a nominal level.

A method of operating a wind turbine wherein the wind turbine includes a doubly-fed induction generator that converts rotational mechanical power to electrical power. The method includes operating the wind turbine in a first operational mode in which a speed of a rotor of the wind turbine is controlled to maximize the power generation by the wind turbine. Upon a monitored parameter reaching or dropping below a respective threshold, the wind turbine is operated in a second operational mode. The monitored parameter may include at least one of the rotational speed of the rotor, the rotational speed of the doubly-fed induction generator, a wind speed, an active electrical power, or generator torque. Operating the wind turbine in the second operational mode may include increasing the rotational speed of the doubly-fed induction generator at the expense of the generation of active electrical power by the power generating system.