Variable speed operation of a wind turbine driven self-excited induction generator connected to a low power DC-link

The paper presents a mathematical model of the self-excited induction generator (SEIG), based on the equivalent circuit, enabling to define its operating point as a function of input torque, speed and phase flux linkage. By this model, a profitable strategy is developed to maximize the power conversion efficiency of a SEIG driven by a variable speed wind turbine and supplying an adjustable load. To apply this procedure to an existing machine, a technique for circuit parameter identification is presented, based on variable supply voltage/frequency no load tests and a variable load torque meter test at rated frequency. This procedure is applied to a real 30 kW-rated induction motor to verify its performance operating as a generator.