STATCOM Controls for a Self-Excited Induction Generator Feeding Random Loads

Voltage and frequency fluctuations due to random load variation are the most important power-quality problem in a self-excited induction generator (SEIG) system. Traditionally, instantaneous voltage regulation can be achieved using static synchronous compensators (STATCOMs) to condition the reactive power flow in a power distribution system. However, their widespread use might be limited by temporary loss of synchronization owing to system frequency fluctuations. In this paper, an advanced, laboratory STATCOM was constructed based on the relative rotation speed theory, which is essential in estimating the frequency deviation and assisting the STATCOM in synchronism with system frequency. As a result, the stator voltage fluctuation due to random load variations can be eliminated and effective regulations in generator speed and mechanical power are thus able to be guaranteed. Both simulation and experimental results are in agreement with the proposed controller, leading to the conclusion that simultaneous voltage and frequency control for SEIG feeding the balanced three-phase loads is feasible.