Woodward Kempen Gmbh

Joerg Kretschmann

Stephan Engelhardt

The invention relates to a method to control power output of a doubly-fed induction machine to a grid including the steps of measuring grid voltage and grid current in a three phase coordinate system, transforming grid voltage and grid current into a stator frame coordinate system, decomposing the grid voltage and grid current in the stator frame coordinate system in a positive sequence system and in a negative sequence system, calculating active and reactive power in the positive and negative sequence system, and controlling active and reactive power in the positive and negative sequence system. The object to provide a method to control power output of a doubly-fed induction machine which provides good dynamics and is able to allow fault-ride-through operations when unbalanced grid voltages occurs is solved in that active and reactive power in the positive and negative sequence system are used as independent state variables in a state controller, whereas the state controller generates manipulated values in the positive and negative sequence system separately which are subjected as manipulated state vectors to a state feedback in a stator frame coordinate system without further control loops before the manipulated vector resulting from state feedback is used to set the rotor voltage.

Direct power control with component separation

The invention relates to a device and method for controlling a double-fed asynchronous machine (), preferably for a power plant, in particular for a wind or water power plant. The device includes an indirect converter () which is connected on the rotor side to the double-fed asynchronous machine (). The indirect converter () includes a rotor-side converter () and a line-side converter (). At least one control element () is provided for controlling the indirect converter (). At least one software-based and/or hardware-based damping element () is provided which has changeable damping characteristics.

Growing community of inventors

Kempen, Germany

Joerg Kretschmann