A system configured to deliver as output a polyphase current of constant frequency from a synchronous generator driven at variable speed. The system includes, at the output of the generator, an AC-to-DC active rectifier including one arm per phase of the current, a DC bus and a DC-to-AC inverter for the output including one arm per phase of the current, the inverter or the DC bus including an arm connected to the neutral, each arm including a controllable switch, the system including an electronic control unit driving the rectifier and including means for tracking a voltage for the rectifier and/or the inverter and means for controlling the inverter, the system including an EMC filter including one arm for each phase of the current, each arm including an inductor, a capacitor connected in a bypass downstream of the inductor, the arm connected to the neutral being connected to each bypass.

The invention relates to a system and method for protecting against faults between turns in excitation windings of synchronous machines with static excitation, which is based on comparison between the excitation intensity measured and the theoretical excitation current calculated for that operating point using the voltage and current measurements in the armature.

A hydroelectric power generation system includes: a generator driven by the hydraulic turbine; a head adjuster adjusting an effective head of the hydraulic turbine; and a controller cooperatively executing: flow rate control for controlling the generator such that a flow rate in the hydraulic turbine is brought close to a target flow rate; and head adjusting control for adjusting the effective head of the hydraulic turbine using the head adjuster such that the effective head of the hydraulic turbine falls within a first range.

A turboelectric generator system includes a gas turbine engine which includes, in fluid flow series, a gas-generator compressor, a combustor, a gas-generator turbine, and a variable-speed free power turbine. The system further comprises a variable-frequency electric machine rotatably connected with the free power turbine and a power converter configured to convert a variable frequency electrical output from the electric machine to a fixed frequency output.

The invention related to a control method for operating a synchronous machine, the machine comprising an exciter connected to a synchronous generator and a controller (40) for controlling the machine field excitation. The method comprises the steps of predefining a stable operation torque derivative range within which a stable operation of the machine occurs, performing a torque measuring or calculating for the machine, calculating the derivative of said torque, determining whether the calculated torque derivative is within the predefined stable operation torque derivative range for the machine, and, if the torque derivative is not within the predefined stable operation torque derivative range, modifying the machine field excitation to bring the torque derivative within the predefined stable operation torque derivative range.

A control circuit, a system and a method 200 of determining a position of a rotor in a permanent magnet motor PM1 in a state when the rotor is freely rotating, the motor being connected to a direct voltage link 101 via an inverter circuit 102, wherein the inverter circuit is operable for connecting windings of a stator of said motor to the direct voltage link, the method comprising the following a step a) short circuiting 201 the windings of the stator of said permanent magnet motor, a step b) measuring 202 a back electromotive force EMF of the short-circuited windings of the stator; and a step c) determining 203 the position of the rotor by means of the measured back EMF.

A rotary machine driving system includes: a rotary machine including a plurality of coils; an inverter device configured to operate the rotary machine at a variable speed, including a control device for controlling power conversion by an inverter circuit, and a coil switching device for switching a connection of the coils according to the control device. The control device commands the coil switching device to switch the connection of the coils when rotation of the rotary machine transitions between a low-speed rotation range and a high-speed rotation range due to acceleration and deceleration. A starting end and a terminal end of at least one set of coils per phase of the rotary machine are drawn out in a freely connectable state. The coil switching device includes at least one movable portion driven by one actuator.

A hybrid power generation unit and synchronous condenser system connectable to a power grid includes a combustion turbine coupled to a first shaft and operable to provide rotational energy to the first shaft, a gear box coupled to the first shaft, and a first clutch portion coupled to the first shaft. A motor is selectively coupled to the gear box to turn the gear box and the first shaft, a second clutch portion is connected to a second shaft, and a generator is coupled to the second shaft. The generator is selectively connectable to the grid to operate as a synchronous condenser when the first clutch portion and the second clutch portion are disengaged and to convert rotational energy from the first shaft to electrical power when the first clutch portion and the second clutch portion are engaged.

A method for modulating a torque ripple and/or a radial force of a three-phase current-operated electric machine includes selecting at least one of a harmonic (HM1_EM) in a torque of the electric machine and a harmonic (HM_X) of a load coupled to the electric machine. The at least one selected harmonic (HM1_EM, HM_X) is modulated by applying the at least one selected harmonic (HM1_EM, HM_X) to a d-current and/or a q-current or to a variable correlated therewith in order to generate a setpoint variable for driving the electric machine A phase angle (φd,k2φqk) of at least one of a harmonic (H.sub.Id) in the d-current and harmonic (H1q) in the q-current is at least temporarily set to be different with respect to a rotor angle,such that φ.sub.d,k ≠φ.sub.q,k applies.

An electrical power supply system, in particular for a microgrid, includes a DC bus, and a first rectifier and a second rectifier, with the first and second rectifiers each supplying power to the DC bus. The first rectifier is a diode rectifier and the second rectifier has switchable power semiconductors. The electrical power supply system further includes a generator supplying power to both rectifiers. The rectifiers can be connected at different times according to a load.