Power quality improvement of small hydro station

Paper presents generation system dedicated to small hydro power station. The conventional generation system uses cage induction generator which demand of reactive power is very high and then its power quality in transients and steady state is very poor. To improve the quality of power, a three level NPC power electronic parallel compensator is applied. The generation system reactive current and power is controlled using voltage oriented method. The rotating x-y frame responds space vector of the grid voltage. To prove such system a laboratory 7.5 kW generation stand was built and tested. The NPC three level converter operation was tested in transient condition during turn-on the generator to grid. As result of compensator operation the peak current was reduced. In steady state the compensator produces reactive power demanded by the generator and then the generation system reactive power demand is null.