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.

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.

A method for operating an asynchronous doubly-fed wind turbine generator connected to a power grid in a grid-forming mode to emulate a virtual synchronous machine. The doubly-fed wind turbine generator includes a line-side converter coupled to a rotor-side converter via a direct current (DC) link. The method includes receiving, via a controller, at least one reference command from an external controller. The method also includes controlling rotor flux of the doubly-fed wind turbine generator using the at least one reference command. Further, the method includes providing power droop control for the doubly-fed wind turbine generator through at least one of rotor-side reference frame rotation and d-axis flux control.

Method of operating a wind turbine in response to a wind speed, the wind turbine having at least a rotor with a plurality of blades and a generator comprising a generator rotor and a generator stator, the method comprising, at wind speeds above a first wind speed, increasing the pitch angle of the blades and reducing the rotor speed with increasing wind speed, said first wind speed being superior to the nominal wind speed; wherein at a second wind speed, the speed of the generator rotor is equal to the synchronous generator rotor speed, said second wind speed being superior to said first wind speed; and wherein at wind speeds superior to said second wind speed, the speed of the generator rotor is lower than the synchronous generator rotor speed.

A method for operating an asynchronous doubly-fed wind turbine generator connected to a power grid in a grid-forming mode to emulate a virtual synchronous machine. The doubly-fed wind turbine generator includes a line-side converter coupled to a rotor-side converter via a direct current (DC) link. The method includes receiving, via a controller, at least one reference command from an external controller. The method also includes controlling rotor flux of the doubly-fed wind turbine generator using the at least one reference command. Further, the method includes providing power droop control for the doubly-fed wind turbine generator through at least one of rotor-side reference frame rotation and d-axis flux control.

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.

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.

The present invention discloses a power generation system including a double-fed induction generator, a power converter, and a controller. The double-fed induction generator includes a rotor and a stator coupled to a grid. The power converter includes a rotor side converter coupled to the rotor of the generator, a grid side converter coupled to the grid, and a DC bus coupled between the rotor side converter and the grid side converter. The controller includes a rotor side controller for controlling the rotor side converter and a grid side controller for controlling the grid side converter. The rotor side controller includes a compensator having a transfer function and configured to counter a negative resistance effect of the generator to suppress sub-synchronous oscillations. The present invention further discloses a system for suppressing sub-synchronous oscillations and a method for controlling operation of a power system.

Provided are a control method and system for enhancing an endurance capability to an abnormal voltage of a wind turbine generator system. The control method, includes; providing a doubly-fed wind turbine generator system connected to a power grid; detecting a voltage of the power grid, and determining whether the voltage of the power grid has a fault; when the voltage of the power grid has a fault, detecting a voltage of the DC buses, and determining whether the voltage of the DC buses exceeds a limit value; when the voltage of the DC buses exceeds the limit value, performing integrated system coordination control according to an abnormal operating condition mode; and when the voltage of the power grid returns to a normal range, performing integrated system coordination control according to a normal operating condition mode.

A method for controlling a wind turbine comprising inputting an actual value of rotational speed and a rotational speed setpoint into a control and outputting a set point value for a generator torque from the control. Inputting the set point value for the generator torque into a limiter with a predefinable upper and lower limit and outputting a limited torque value that is fed into a converter control. Increasing the actual value of the fed-in electrical power by an additional amount of power in response to a boost signal, wherein the fed-in electrical power and the additional amount of power are combined into an aggregated power setpoint value. Determining the set point value for the generator torque from the aggregated power setpoint value and applying the set point value for the generator torque in the boost operation to the limiter both as the upper limit and as the lower limit.