Abstract: The subject matter described herein includes an active compensatory augmented diode bridge rectifier system. According to one aspect, the system includes a generator unit configured to generate a current flow made up entirely of active current and a diode rectifier configured to receive the active current from the generator unit, to direct the active current to a connected power grid, and to receive a reactive current. The system further includes an active compensator configured to optimize the generator unit to produce the active current and to generate the reactive power used to facilitate the operation of the diode rectifier.

Abstract: The subject matter described herein includes an active compensatory augmented diode bridge rectifier system. According to one aspect, the system comprises a generator unit configured to generate a current flow comprised entirely of active current and a diode rectifier configured to receive the active current from the generator unit, to direct the active current to a connected power grid, and to receive a reactive current. The system further includes an active compensator configured to optimize the generator unit to produce the active current and to generate the reactive power used to facilitate the operation of the diode rectifier.

Abstract: A wind mill apparatus for generating electric power to a grid point of an electric network. The apparatus includes a wind rotor, an electric generator operatively connected to the wind rotor, and an electric multiphase ac link operatively connecting the generator to the grid point. The ac link includes a first current path including a switchgear, a second current path including a dc link including a first converter operatively connected to the generator, a second converter operatively connected to the grid point, and a capacitor operatively connected between the conductors of the dc link. The ac link further includes a connectable multiphase dump load for blocking during a fault condition on the network the reactive power flow in the ac link, yet providing a reduced transfer of active power.

Abstract: A method and arrangement for controlling a doubly-fed induction machine by a frequency converter including a rotor side converter (INU) connected to a rotor circuit of a doubly-fed induction machine (DFIG) and having a control system with rotor flux as a feedback variable, a grid side converter (ISU) connected to an AC power network, and a direct voltage intermediate circuit (DC) connected between the rotor side converter (INU) and the grid side converter (ISU). The method includes forming a rotor flux reference (?r,ref), forming a damping signal (?ref,D), summing the damping signal and the rotor flux reference for obtaining a modified rotor flux reference (?ref), and feeding the modified rotor flux reference to a controller of the rotor side converter (INU) for damping sub-synchronous resonances.

Abstract: A wind mill apparatus for generating electric power to a grid point of an electric network. The apparatus includes a wind rotor, an electric generator operatively connected to the wind rotor, and an electric multiphase ac link operatively connecting the generator to the grid point. The ac link includes a first current path including a switchgear, a second current path including a dc link including a first converter operatively connected to the generator, a second converter operatively connected to the grid point, and a capacitor operatively connected between the conductors of the dc link. The ac link further includes a connectable multiphase dump load for blocking during a fault condition on the network the reactive power flow in the ac link, yet providing a reduced transfer of active power.

Abstract: A power converter arrangement for connecting an induction generator to an electric power network comprises a first path provided for transferring electric power from the induction generator to the electric power network during a first operation condition, and a second path provided for transferring electric power from the induction generator to the electric power network during a second operation condition, where the first path includes an AC-AC converter and the second path includes a switch. A capacitor arrangement is interconnected between the induction generator and the first and second paths and a first AC reactor device is interconnected between the capacitor arrangement and the first and second paths, where the capacitor arrangement is provided for compensating for a magnetization current of the induction generator.

Abstract: A power converter arrangement for connecting an induction generator to an electric power network comprises a first path provided for transferring electric power from the induction generator to the electric power network during a first operation condition, and a second path provided for transferring electric power from the induction generator to the electric power network during a second operation condition, where the first path includes an AC-AC converter and the second path includes a switch. A capacitor arrangement is interconnected between the induction generator and the first and second paths and a first AC reactor device is interconnected between the capacitor arrangement and the first and second paths, where the capacitor arrangement is provided for compensating for a magnetization current of the induction generator.

Abstract: An arrangement and a method for starting a slip-ring machine, the arrangement comprising a frequency converter arranged to be connected between a supply network and a rotor of the slip-ring machine for controlling the slip-ring machine, and starting means for starting the slip-ring machine. The starting means are arranged between the frequency converter and the rotor of the slip-ring machine, whereby the frequency converter is arranged to control the magnitude of the current of the rotor of the slip-ring machine in connection with starting the slip-ring machine.

Abstract: Method for defining quadrature-axis magnetizing inductance of a synchronous machine, the synchronous machine being supplied by an inverter. The method comprises steps, wherein the synchronous machine is started without load or with reduced load; the rotor current of the synchronous machine is kept substantially at zero, the synchronous machine is accelerated to initial angular velocity of measurement, the load angle (ds) of the synchronous machine is guided substantially to 90 degrees, the stator voltage (us), the stator current (is) and the electrical angular velocity (?) of the synchronous machine is defined and the quadrature-axis magnetizing inductance of the synchronous machine (lmq) is defined on the basis of the stator voltage (us), the stator current (is) and the electrical angular velocity (?) of the machine.

Abstract: An arrangement and a method for starting a slip-ring machine, the arrangement comprising a frequency converter arranged to be connected between a supply network and a rotor of the slip-ring machine for controlling the slip-ring machine, and starting means for starting the slip-ring machine. The starting means are arranged between the frequency converter and the rotor of the slip-ring machine, whereby the frequency converter is arranged to control the magnitude of the current of the rotor of the slip-ring machine in connection with starting the slip-ring machine.

Abstract: Method for defining quadrature-axis magnetizing inductance of a synchronous machine, the synchronous machine being supplied by an inverter. The method comprises steps, wherein the synchronous machine is started without load or with reduced load; the rotor current of the synchronous machine is kept substantially at zero, the synchronous machine is accelerated to initial angular velocity of measurement, the load angle (ds) of the synchronous machine is guided substantially to 90 degrees, the stator voltage (us), the stator current (is) and the electrical angular velocity (?) of the synchronous machine is defined and the quadrature-axis magnetizing inductance of the synchronous machine (lmq) is defined on the basis of the stator voltage (us), the stator current (is) and the electrical angular velocity (?) of the machine.