Full expandable model of parallel self-excited induction generators

Self-excited induction generators (SEIG) offer many advantages as variable-speed generators in renewable energy systems. Small hydro and wind generating systems have constraints on the size of individual machines, and several induction generators must be paralleled in order to access fully the potential of the site. SEIGs connected in parallel may lose excitation momentarily owing to large transient currents caused by differences in individual instantaneous voltages and frequency. This phenomenon cannot be easily simulated using the conventional models because it has such a fast transient nature. An innovative and automatic numerical solution for steady-state and transient analysis of any number of SEIGs operating in parallel is presented. Experimental results confirm the accuracy of the proposed model and open new possibilities for incorporating advanced control to monitor and optimise a parallel installation of SEIGs. The proposed SEIG model is applied to a two-turbine case, which can be extended to simulate a wind generating system.