A New Electronic Load Controller for the Self-excited Induction Generator to Decrease Stator Winding Stress

Abstract

Constant voltage and frequency can be generated by a Self-Excited Induction Generator (SEIG) driven with a fixed-speed low-head hydro-turbine when a constant electrical load is maintained by an Electronic Load Controller (ELC). In the Conventional-ELC (C-ELC), usually a chopper with a dump load is used in parallel with the consumer loads to provide regulation of voltage and control of frequency. In the C-ELC configuration a high degree of stress can be experienced by stator windings and excitation capacitors resulting from chopper operation, since in each chopping period the dump load is connected to the stator winding for a short period then disconnected. A new ELC topology is proposed to reduce this stress. Compared with the C-ELC, the main dump load has been divided into two separated parts. A part of the dump load can be connected in parallel with the consumer loads, resulting in less variation in the total load seen by the SEIG and less stress on the stator windings and excitation capacitors. This proposed topology can be utilized per-phase using bi-directional power switches, hence it can operate with unbalanced consumer loads. Simulation results demonstrate that even with unbalanced three-phase loads (assisted with bi-directional switches per-phase), the proposed topology has the capability to regulate voltage from no-load to full load. Moreover, the Total Harmonic Distortion (THD) analysis for output (stator) current shows a 9% improvement compared with the most recent results in the literature.