The present subject matter is directed to an electrical power circuit connected to a power grid and method of operating same. The electrical power circuit has a power converter electrically coupled to a generator, such as a doubly-fed induction generator, having a rotor and a stator. Thus, the method includes operating rotor connections of the rotor of the generator in a wye configuration during a first rotor speed operating range. Further, the method includes monitoring a rotor speed of the rotor of the generator. Thus, the method also includes transitioning the rotor connections of the rotor from the wye configuration to a delta configuration if the rotor speed changes to a second rotor speed operating range.

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.

An actuating device of a pump of a fuel pumping system of an engine, including a motor, a generator, an inverter, a switching member and a control member, the motor including a first rotor coupled to the pump and a first stator including at least one input stator winding, the generator including a second rotor coupled to a drive shaft of the engine, and a second stator including at least one output stator winding, the control member being configured to control the switching member in order to selectively connect each input stator winding: to a corresponding output stator winding if a speed of the engine is higher than or equal to a predetermined speed; to a corresponding output of the inverter, otherwise.

A propulsion channel for aircraft at least one first dual-fed polyphase asynchronous rotating electric machine configured to be mechanically coupled to a turbine engine. The propulsion channel further includes at least one second polyphase rotating electric machine electrically coupled to the first asynchronous rotating electric machine, and a control and storage module configured to control the first polyphase asynchronous rotating electric machine. The module is connected to the first dual-feed polyphase asynchronous rotating electric machine as well as to the at least second polyphase rotating electric machine. The at least second polyphase rotating electric machine includes a polyphase synchronous rotating electric machine with permanent magnet.

An object of the present invention is to provide a drive system that is provided with an induction generator having a primary winding including a main winding and an auxiliary winding and a secondary conductor, can vary the voltage of the main winding, and can increase the maximum output power of the auxiliary winding. Therefore, provided is a drive system, which is provided with an induction generator having a primary winding including a main winding and an auxiliary winding and a secondary conductor, including: a starting battery that starts the induction generator; a traction inverter that drives a traction motor; an auxiliary device inverter that drives an auxiliary device motor; a rectifier the input side of which is connected to the main winding and the output side of which is connected to the traction inverter; and a power generation inverter the output side of which is connected to the auxiliary winding and the input side of which is connected to the auxiliary device inverter and the starting battery.

A wind power generating system includes: a wind mill, an induction rotating machine coupled to a rotating shaft of the wind mill; a power converting device that supplies exciting current to the induction rotating machine; a heat medium circulating structure that circulates a heat medium that receives heat generated by the induction rotating machine; a heat accumulator that accumulates heat of the heat medium; a thermal power generator that converts, into electric power, the heat of the heat medium accumulated in the heat accumulator; and an armature control unit that controls the exciting current in accordance with electric power demand of an electric power system. The armature control unit performs one or both of power generation mode control in which the induction rotating machine is operated as a power generator and heat generation mode control in which the induction rotating machine is operated as a heat generator.

A control system configured to control switching of taps of an on-load tap changer provided on an electric power transformer. The on-load tap changer includes switches that are controllable to switch between transformer taps. The control system includes a detector configured to detect an indication of a zero crossing of a transformer voltage of the transformer and a control signal generator configured to generate a control signal that controls a switching of the switches for performing a tap change to a new transformer tap. The control signal generator is configured to determine the timing of the control signal for changing the transformer tap based on the detected indication of the zero crossing of the transformer voltage such that the switching of at least one of the switches for performing the tap change occurs a predetermined time prior to a zero crossing of a tap voltage at the new transformer tap.

A hybrid asynchronous induction machine includes a stator disposed in a stator housing, the stator comprising an input winding for a polyphase input signal, a primary output winding and a secondary output winding. The machine also includes a rotor having a shaft connected to a flywheel of an energy storage unit. The rotor comprises a primary rotor winding for a polyphase AC excitation signal and a secondary rotor winding for bidirectional power flow. The hybrid asynchronous induction machine is further configured to receive a compensation signal for cancelling low-frequency electrical resonances.

A method of controlling the operation of a doubly fed induction machine is provided. The DFIM includes a stator electrically coupled to a power grid and a rotor rotating with a rotational speed. The DFIM has a synchronous rotational speed of the rotor and a rated rotational speed of the rotor. Rotation of the rotor at the synchronous rotational speed generates one or more slot harmonic distortions having a harmonic order. The method comprises operating the DFIM at the rated rotational speed of the rotor, wherein the rated rotational speed of the rotor is set to a value selected such that a shift of the harmonic order of one or more of the slot harmonic distortions at the rated rotational speed of the rotor is an integer number or is within a predefined limit of an integer number.

A system for supporting the stability of an electrical grid comprises an asynchronous electric machine with an accessible rotor circuit and a stator with a stator circuit connected to the grid. A flywheel is coupled to the rotor, for the machine to absorb electric energy and store it as kinetic energy, and to convert the stored kinetic energy in electric energy to be delivered to the grid A static converter is connected between the grid and the rotor circuit An electronic control measures a grid frequency and determines ROCOF values, being a derivative of the frequency In case of a change in the frequency, the machine immediately provides an uncontrolled natural inertial response. Moreover, the static converter is controlled such that the machine supplies a controlled synthetic inertial response wherein the active power absorbed/supplied is modulated according to the determined ROCOF value and the uncontrolled natural inertial response already provided.