Transient behaviour of an induction generation in small hydro plants

The transient behavior of an induction generator in a small hydro plant following disturbances in the utility´s transmission and distribution system was studied, and some conclusions concerning the protection and control of small hydro plants with induction generators are drawn. Two perturbations were considered: a sudden loss of load situation and a three-phase short circuit in the feeder. In both cases it was assumed that reclosure of the utility´s breaker would occur. From the studies performed it was concluded that the relays operated properly. In the situations considered both the over-frequency and the under-frequency relays were inhibited. It is stressed that the results are strongly dependent on the sizing of the shunt capacitor bank