Ge Energy Power Conversion Technology Gmbh

Kai Alexander Rothenhagen

Duro Basic

Piotr Sadowski

Aurélie Bocquel

Niels Weitendorf

A doubly-fed induction generator (DFIG) system is described. The DFIG system includes an induction electric machine including a stator having a stator winding and a rotor having a rotor winding. The stator winding is electrically connected to at least one output terminal and the rotor winding is electrically connected to the at least one output terminal by means of a power converter. The power converter includes a first active rectifier/inverter with alternating current AC terminals electrically connected to the rotor winding, and direct current DC terminals, and a second active rectifier/inverter with DC terminals electrically connected to the DC terminals of the first active rectifier/inverter by a DC link, and AC terminals electrically connected to the at least one output terminal. A controller is adapted to control the first active rectifier/inverter so that the frequency of the AC current at its AC terminals is substantially constant during at least one of a 'line charging mode' and an “islanded mode”.

Methods of operating doubly-fed induction generator systems

A system and method of operating a pumped storage power plant using a double fed induction machine with a frequency converter in a rotor circuit is disclosed. A current target value for the rotor current frequency is determined based on a target power to be transmitted between an electrical grid and the double fed induction machine depending on measured actual operating variables. A current inadmissible synchronous deadband is determined depending on variables characterizing a current state of the pumped storage power plant. The synchronous deadband is determined by a permissible minimum required rotor current frequency or speed difference of the rotor speed from the synchronous speed for the stationary operation. The converter is controlled to generate voltages and currents with the current target value of the rotor current frequency if the current target value of the rotor current frequency or speed does not fall in the current inadmissible synchronous deadband.

System and method for operating a pumped storage power plant with a double fed induction machine

A method for controlling a back-to-back three-phase three-level converter having a grid-side AC/DC converter and a machine-side DC/AC converter connected by a split DC link which defines a DC link midpoint. The method includes controlling the grid-side converter to convert AC power from a grid into DC power of the DC link, controlling the machine-side converter to convert DC power from the DC link to AC power to feed a low frequency machine, and concurrently performing common mode voltage injection for the machine-side converter so as to at least partially compensate midpoint voltage ripple caused by the machine-side converter. The method further includes performing common mode voltage injection for the grid-side converter so as to at least partly further compensate the portion of the midpoint voltage ripple which remains uncompensated by controlling the machine-side converter. A control system implementing the control method and a power conversion system utilizing same.

System and method for controlling a back-to-back three-level converter with voltage ripple compensation

A method is disclosed to protect a power converter arrangement with a power converter that has a DC side that is connected to a DC intermediate circuit, an AC side, and controllable switches that can be controllably switched at a high frequency to invert the DC voltage of the DC intermediate circuit into an AC voltage. A protective device that can be activated and deactivated is provided to protect the power converter from overload by connecting an external thyristor rectifier bridge with a brake resistor (R) to the AC side of the power converter. If a predetermined error situation is detected, the external thyristors are triggered to turn on, to activate the protective device. If it is detected that the predetermined error situation has disappeared, the external thyristors are turned off. A power converter arrangement with a device to protect against overload is also disclosed.

Method to protect a power converter arrangement and power converter arrangement with a protective device

A multi-phase electric circuit including an electric machine and an inverter, wherein machine encompasses a rotor connected to the inverter via at least two brushes for each phase, wherein each of the brushes of each phase is connected to the inverter via a separate brush line.

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Berlin, Germany

Kai Alexander Rothenhagen