6 MVA five-level hybrid converter for windpower

For the further improvement of today´s full converter systems for windpower applications a 6 MVA converter prototype has been developed. It is utilizing the ANPC5L topology as inverter on the grid-side and the simple 2-quadrant ANPC3L topology as rectifier for a permanent magnet synchronous generator (PMG). ANPC stands for Active Neutral Point Clamped, which is the base for the derivation of multiple topologies, i.e. 3-, 5- and higher levels. The ANPC5L converter is realized as a hybrid converter based on IGCT (Integrated Gate Commutated Thyristor) presspack devices and IGBT (Insulated Gate Bipolar Transistor) modules. The ANPC5L is modulated at 2 kHz. The IGCTs, used as inner switches, are operated at fundamental frequency, which allows a substantial reduction in silicon size. To meet the harmonic limits of the IEEE 519 no additional passive filter is required. To fulfill the more stringent VDEW requirements a simple LC filter is implemented. On the permanent generator side a simplified 2-quadrant 3 level converter (2Q-ANP3L), with 50% less turn-off switches than in a conventional NPC converter, is used. The operation of this simple topology with a discontinuous modulation allows the adjustment of the power factor of the permanent magnet synchronous generator for all operation conditions. The 6 MVA converter has been designed, built and tested in the power lab. The dimensions of the 6 MVA converter prototype, represents one of the most compact designs achieved for windpower applications today.