Balanced Performance of Three-phase SEIG Supplying Off-grid Single-phase Power Using a Passive Excitation Scheme

Harnessing and supplying off-grid single-phase power from a three-phase self-excited induction generator (SEIG) leads to a significant imbalance in stator phase voltages and currents. This paper presents a passive (capacitor-based) phase-balancing excitation scheme for supplying single-phase loads from a micro-hydro-driven three-phase SEIG. The steady-state behavior of the proposed scheme is analyzed using symmetrical component theory and two-port network representation to examine system performance under variable generator speed and different resistive (R) and resistive–inductive (RL) loading conditions. In addition, a detailed transient analysis is carried out using a stationary αβ0 reference frame–based dynamic model to investigate voltage and current build-up, sudden load switching, and balance restoration. The results show that, for a given load, the phase-balancing capacitor values remain nearly invariant with respect to varying SEIG speed, enabling balanced operation without the use of power electronic interfaces. Simulation studies performed in the MATLAB/Simulink environment and experimental validation on a 2.2 kW laboratory prototype demonstrate near-zero voltage and current unbalance factors, along with acceptable voltage regulation of approximately 0.65% for an R load and 4.39% for an RL load at rated speed. Comparative evaluation with well-known excitation schemes further confirms the effectiveness of the proposed approach for off-grid single-phase power generation.