A method is provided for controlling a wind turbine that has a generator that is controlled via a converter in a boost operation, in which an electrical power that is fed into an electrical transmission network is increased via a generative deceleration of the generator. The method comprises using a control to determining a set point value for a generator torque depending on an actual value of a rotational speed. The determined set point value for the generator torque is applied to a generator via a limiter with a predefinable upper and lower limit. Determining the set point value for the generator torque in boost operation that leads to an increased fed-in electrical power in response to a boost signal; and limiting a temporal change of the set point value for the generator torque in a recovery operation in response to a recovery signal.

A wind turbine system is described comprising a plurality of wind turbine modules, each including a rotor, mounted to a support structure including a tower. In use, each rotor has an associated rotating unbalance that defines an unbalance vector. The wind turbine system includes control means configured to coordinate the rotational speeds of the plurality of rotors to attenuate oscillations of the support structure caused by the rotating unbalance of the rotors. Also described is a method of controlling such a wind turbine system. The method comprises coordinating the rotational speeds of the plurality of rotors to attenuate oscillations of the support structure caused by the rotating unbalance of the rotors.

A hydropower plant for regulating the frequency of an electric grid has an upper water reservoir, a lower water reservoir, and a waterway that connects the upper water reservoir to the lower water reservoir. A turbine is arranged in the waterway and includes a runner, a guide vane apparatus and a device for blowing out the runner space. An electric double-fed asynchronous machine is mechanically connected to the turbine and a frequency converter is electrically connected to the asynchronous machine. A mains transformer is electrically connected to the asynchronous machine, frequency converter and mains grid. A resistor is arranged in a DC intermediate circuit of the frequency converter in such a way that it may connect the line sections of the DC intermediate circuit to one another. There is also provided a device for cooling the resistor.

A power converter assembly for an electrical power system connected to a power grid includes a rotor-side converter configured for coupling to a generator rotor of a generator of the electrical power system, a line-side converter electrically coupled to rotor-side converter via a DC link, and a dynamic brake assembly electrically coupled to the DC link. The line-side converter is configured for coupling to the power grid. The dynamic brake assembly includes a plurality of switching devices connected in parallel and a plurality of inductors electrically coupled between the plurality of switching devices.

A power converter assembly for an electrical power system connected to a power grid includes a rotor-side converter configured for coupling to a generator rotor of a generator of the electrical power system, a line-side converter electrically coupled to rotor-side converter via a DC link, and a dynamic brake assembly electrically coupled to the DC link. The line-side converter is configured for coupling to the power grid. The dynamic brake assembly includes a plurality of switching devices connected in parallel and a plurality of inductors electrically coupled between the plurality of switching devices.

A method is provided of protecting a wind turbine with a doubly-fed induction generator (DFIG) against a sub-synchronous resonance (SSR) event acting on the wind turbine. A plurality of power-output values or current-output values is measured over a given period of time that corresponds to a measurement cycle. It is determined whether power-output values or current-output-values measured in the at-least-one measurement cycle are indicative of an SSR-event critical for further operation of the wind turbine. The wind turbine is shut down if the measured power-output values or current-output values are indeed indicative of an SSR-event critical for operation of the wind turbine.

Unique systems, methods, techniques and apparatuses of hybrid power plants are disclosed. One exemplary embodiment is a hybrid power plant system including a plurality of hybrid generation units each including an AC collection bus, an AC power source, an AC-AC power converter coupled to the AC power source and AC collection bus, a DC power source, a DC-AC converter coupled to the DC power source and the AC collection bus, an energy storage device, and a power transformer coupled to the AC collection bus and structured to receive AC power from the AC collection bus, step up a voltage of the received AC power, and output medium voltage AC (MVAC) power.

Systems and methods for operating an energy storage system in a wind turbine system are provided. A wind turbine system can include a wind turbine, a power conversion system operably coupled to the wind turbine and an AC line bus, and an energy storage system coupled to the AC line bus. The energy storage system can include a transformer, a power converter, and an energy storage device and can be configured to store and provide power generated by the wind turbine. The method can include operating the wind turbine system to generate power, determining one or more operating parameters for the wind turbine system, determining an operating mode based on the one or more operating parameters, and controlling the wind turbine system based at least in part on the operating mode. Controlling the wind turbine can control a power flow into or out of the energy storage system.

A method for a method for minimizing inrush of current during start-up of an alternating current (AC) electrical power system connected to a power grid includes determining a grid voltage of the power grid. The method also includes charging an AC capacitance of a grid filter of the electrical power system from an initial capacitance value to a predetermined percentage of the grid voltage. Further, the method includes connecting the electrical power system to the power grid when the AC capacitance in the grid filter reaches the predetermined percentage of the grid voltage. Moreover, the method includes initiating start-up of the electrical power system.

The present disclosure is directed to an energy storage system including a power source and a power converter coupled to the power source. The power converter is configured to output power suitable for consumption in a utility grid. The energy storage system also includes an energy storage device configured to receive the power output from the power converter and a charge discharge converter coupled between the power converter and the energy storage device. The charge discharge converter is configured to control at least one of charging or discharging the energy storage device. Furthermore, the energy storage device includes a transformer coupled between the charge discharge converter and the power converter.