24 MW, 75±15 rpm, dc-excited high voltage synchronous wind generator system with diode rectified controlled 60 kV d.c. output: preliminary design with key FEM validations

Source abstract

Super power wind generators, especially in off shore implementation require voltage boosting to say 60 kV d.c. for a 50+ km off shore sites to reduce cable weight, cost, losses. A d.c. excited synchronous at unity power factor generator designed to deliver directly power in d.c. at 60 kV dc, via a diode 12 pulse rectifier would imply the elimination of full power transformer with its high-cost power interrupter on load and separator on no-load. Also, the diode rectifier reduces the system cost while securing a high efficiency for d.c. output. Building up on an earlier attempt (power former) but suggesting a tooth wound winding with q1=2/5 made of nonoverlapping cable coils and a possible 1000 kW non-contacting induction rotary transformer at 500 Hz to supply the d.c. excitation on the rotor constitutes the core of the present paper. Preliminary analytical model based electromagnetic design of a 24 MW, 60 kV d.c. output synchronous generator (SG) is accompanied by key FEM validation to sustain the feasibility of the proposed solution.