Abstract: The present disclosure is directed to a system comprising a structure being prone to lightning strikes and icing, wherein the structure comprises a shielding arrangement electrically connected to a lightning arrangement, an electric heating arrangement connected to a power source for mitigating icing of the structure, and an electrical insulation arrangement being effectively provided between the shielding arrangement and the electric heating arrangement. A power source is configured for applying a predetermined amount of electric test- and/or maintenance-energy such that the electric test- and/or maintenance-energy is effectively present between the shielding arrangement and the electric heating arrangement. A determination device is electrically connected to the shielding arrangement and to the electric heating arrangement in a way that the shield-heating-voltage and/or the shield-heating-current being present between the shielding arrangement and the electric heating arrangement can be determined.

Abstract: A method for controlling an active harmonic filter of an inverter-based resource includes receiving, via a maximum compensation tracker module, a grid feedback signal, determining, via the maximum compensation tracker module, a phase shift signal based, at least in part, on the grid feedback signal, applying, via the maximum compensation tracker module, a phase shift offset signal to the phase shift signal to obtain a modified phase shift signal, determining, via the maximum compensation tracker module, a voltage reference signal for the active harmonic filter based, at least in part, on the grid feedback signal and the modified phase shift signal; and controlling, via the maximum compensation tracker module, the active harmonic filter using the voltage reference signal, wherein the phase shift offset signal ensures that the active harmonic filter injects a current substantially out of phase of a targeted harmonic.

Abstract: A method for controlling a wind farm having a plurality of wind turbines electrically connected to an electrical grid through a point of interconnection includes (a) determining, via a controller of the wind farm, a phase and an amplitude of individual power oscillations from each of the plurality of wind turbine power systems. The method also includes (b) determining, via the controller, a farm-level power oscillation for the wind farm based on the individual power oscillations from each of the plurality of wind turbine power systems. Further, the method includes (c) implementing, via the controller, a phase-shifting control scheme using the phases and the amplitudes of the individual power oscillations from each of the plurality of wind turbine power systems so as to maintain the farm-level power oscillation below a predetermined oscillation threshold.

Abstract: A wind turbine and operating method include a double-fed induction generator with a generator rotor and a generator stator, a power conversion assembly having respective rotor-side and line-side power converters, and a load. The generator rotor is coupled to the rotor-side power converter. The line-side power converter and the load are coupled to a grid via a low voltage winding of a transformer. A first sum of a rated current of the generator rotor and a rated current of the load is more than an upper current limit of the low voltage winding. When operating the generator at a sub-synchronous speed, a first current is provided to the generator rotor that is less than a normal generator rotor current, and a second current is provide to the load, wherein a second sum of the first current and the second current is equal to or less than the upper current limit of the low voltage winding.

Abstract: A method for operating a power supply system connected to a grid, the power supply system including a rotor, a doubly-fed induction generator (DFIG), a power conversion assembly, and an active filter. The DFIG includes a generator rotor mechanically connected with the rotor and a generator stator. The power conversion assembly includes a rotor-side power converter. The active filter electrically connected with the generator stator via a stator bus and the rotor-side power converter electrically connected with the generator rotor via a rotor bus. Based on a rotor frequency of the generator rotor, the method determines an expected harmonic frequency for a stator current flowing on the stator bus. An amplitude of the stator current at the expected harmonic frequency is determined via a data set of stator current values. The method controls the active filter based on the amplitude of the stator current at the expected harmonic frequency.

Abstract: It is provided a wind turbine and methods of operating a wind turbine as described herein.

Abstract: The present disclosure is directed to a system comprising a structure being prone to lightning strikes and icing, wherein the structure comprises a shielding arrangement electrically connected to a lightning arrangement, an electric heating arrangement connected to a power source for mitigating icing of the structure, and an electrical insulation arrangement being effectively provided between the shielding arrangement and the electric heating arrangement. A power source is configured for applying a predetermined amount of electric test- and/or maintenance-energy such that the electric test- and/or maintenance-energy is effectively present between the shielding arrangement and the electric heating arrangement. A determination device is electrically connected to the shielding arrangement and to the electric heating arrangement in a way that the shield-heating-voltage and/or the shield-heating-current being present between the shielding arrangement and the electric heating arrangement can be determined.

Abstract: The system and method described herein provide grid-forming control of a power generating asset having a generator, such as 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 damping component corresponding to a tower damping 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.

Abstract: A method for controlling an inverter-based resource having an asynchronous machine connected to a power grid to provide grid-forming control of the inverter-based resource includes coupling at least one additional device to terminals of a first converter of the inverter-based resource. Further, the method includes emulating, via a controller, at least one of the at least one additional device or the first converter as a first virtual synchronous machine. Moreover, the method includes coordinating, via the controller, operation of the first virtual synchronous machine and a second converter of the inverter-based resource using a vector-control approach to control at least one of voltage and frequency at a point of interconnection between the inverter-based resource and the power grid in a closed loop manner.

Abstract: A method for controlling an inverter-based resource having an asynchronous machine connected to a power grid to provide grid-forming control of the inverter-based resource includes coupling at least one additional device to terminals of a first converter of the inverter-based resource. Further, the method includes emulating, via a controller, at least one of the at least one additional device or the first converter as a first virtual synchronous machine. Moreover, the method includes coordinating, via the controller, operation of the first virtual synchronous machine and a second converter of the inverter-based resource using a vector-control approach to control at least one of voltage and frequency at a point of interconnection between the inverter-based resource and the power grid in a closed loop manner.

Abstract: A method for compensating for flicker induced by a wind turbine power system connected to a power grid includes operating a power converter of the wind turbine power system based on a nominal reactive current command and a nominal torque command. In response to receiving a periodic torque command modifier, the method includes determining a reactive current command modifier for the power converter based on one or more operational parameters of the wind turbine power system and/or the power grid and the torque command modifier. The method also includes simultaneously modifying the nominal reactive current command as a function of the reactive current command modifier and the nominal torque command as a function of the torque command modifier. Accordingly, modifying the nominal torque command causes low-frequency voltage variations in the power grid and simultaneously modifying the reactive current command attenuates the low-frequency voltage variations.

Abstract: A method for compensating for flicker induced by a wind turbine power system connected to a power grid includes operating a power converter of the wind turbine power system based on a nominal reactive current command and a nominal torque command. In response to receiving a periodic torque command modifier, the method includes determining a reactive current command modifier for the power converter based on one or more operational parameters of the wind turbine power system and/or the power grid and the torque command modifier. The method also includes simultaneously modifying the nominal reactive current command as a function of the reactive current command modifier and the nominal torque command as a function of the torque command modifier. Accordingly, modifying the nominal torque command causes low-frequency voltage variations in the power grid and simultaneously modifying the reactive current command attenuates the low-frequency voltage variations.

Abstract: A method for operating a turbine having a rotor including a hub and at least one blade rotatably arranged around its longitudinal axis at the hub, an induction generator having a stator and rotor coupled to the turbine shaft, a pitch drive system having an actuator, a control system, and a measuring device. The method includes: measuring the operational value of a component of the pitch drive system and adjusting the angle to the target pitch angle, wherein the wind turbine is operated according to at least two operational modes. During a first mode, a first target pitch angle is determined at least according to a power curve of the wind turbine or measured wind speed. During a second mode, a second target pitch angle is determined by adding a pitch offset to the first target pitch and is activated when the measured operational value exceeds a predefined activation threshold.

Abstract: The present subject matter is directed to a wind turbine electrical power configured to minimize power losses. The power system includes a generator having a generator stator and a generator rotor, a power converter electrically coupled to the generator, a main transformer electrically coupled to the power converter and the power grid, and an auxiliary transformer. More specifically, the main transformer is connected to the power grid via a voltage line comprising a voltage switch gear. Thus, the auxiliary transformer is connected directly to the voltage line, i.e. rather than being connected to the grid through the main transformer.

Abstract: System and methods for optimizing operation of a wind turbine are disclosed. In one aspect, the method also includes determining, via a converter controller of a power converter, a tap position of a tap changer configured between the power grid and a primary winding of a transformer. Another step includes calculating, via the converter controller, a primary voltage of the primary winding as a function of the tap position. The method also includes implementing, via the converter controller, a control action if the primary voltage or a measured secondary voltage of a secondary winding of the transformer is outside of a predetermined voltage range.

Abstract: The present subject matter is directed to a method for initializing a startup sequence of a wind turbine. The method includes a step of defining a plurality of operating conditions of the wind turbine. As such, upon satisfaction of the plurality of operating conditions, a run-ready signal may be generated, wherein the run-ready signal indicates a readiness of a power converter of the wind turbine to generate power. The method may also include defining a subset of the plurality of operating conditions, wherein the subset of operating conditions are independent of speed conditions of the wind turbine. Another step of the method includes generating a spin-ready signal for the wind turbine upon satisfaction of the subset of operating conditions. The method may also include controlling a rotor of the wind turbine based at least in part on the spin-ready signal.

Abstract: The present subject matter is directed to a wind turbine electrical power configured to minimize power losses. The power system includes a generator having a generator stator and a generator rotor, a power converter electrically coupled to the generator, a main transformer electrically coupled to the power converter and the power grid, and an auxiliary transformer. More specifically, the main transformer is connected to the power grid via a voltage line comprising a voltage switch gear. Thus, the auxiliary transformer is connected directly to the voltage line, i.e. rather than being connected to the grid through the main transformer.

Abstract: A method for operating a turbine having a rotor including a hub and at least one blade rotatably arranged around its longitudinal axis at the hub, an induction generator having a stator and rotor coupled to the turbine shaft, a pitch drive system having an actuator, a control system, and a measuring device. The method includes: measuring the operational value of a component of the pitch drive system and adjusting the angle to the target pitch angle, wherein the wind turbine is operated according to at least two operational modes. During a first mode, a first target pitch angle is determined at least according to a power curve of the wind turbine or measured wind speed. During a second mode, a second target pitch angle is determined by adding a pitch offset to the first target pitch and is activated when the measured operational value exceeds a predefined activation threshold.

Abstract: A method for controlling the power output of a wind turbine, which includes a transformer with multiple taps, is provided. The method includes sensing a voltage of the transformer during operation of the wind turbine, determining the reactive power, and automatically maintaining a set value of the reactive power by controlling the output voltage of the transformer.

Abstract: Systems and methods for controlling a renewable energy system based on actual reactive power capability of the renewable energy system are provided. The reactive power output of the renewable energy system can be controlled based at least in part on an initial reactive power limit. The initial reactive power limit can be determined based on rated reactive power for the power generation units in the renewable energy system. When a difference between a reactive power demand and the actual reactive power production of the renewable energy system fall outside a threshold, the initial reactive power limit can be adjusted to a corrected reactive power limit that is closer to the actual reactive power capability of the renewable energy system.