Voltage and frequency control for island operated induction generators

Over the last few years the interest in distributed generation and island operation of small production units has increased. Many of the existing such units are hydro power stations with induction generators. These are not initially constructed for island operation, but with some extra equipment this kind of operation is feasible. In this paper the behaviour of two parallel-operated induction generators driven by hydro turbines are studied during load steps. The influence of a STATCOM based voltage regulator is also investigated and it is shown that a fast voltage regulator may not be desirable for induction generators in combination with hydro turbines.