SIMULATION OF VARIABLE SPEED SMALL HYDRO POWER PLANT

Abstract

This work deals with the simulation of a grid connected variable speed Small Hydro Power Plant. When the SHP plants face a large variation of discharge throughout the year, it is advantageous to use Variable Speed Generation. With the variation of discharge efficiency decreases very sharply at constant speed operation.. By variable speed operation high efficiency gain can be achieved at part load conditions. Potential advantages of variable speed hydroelectric generation are discussed in this work. Some general aspect of efficiency gain in turbines and improvement in plant operation are analysed. Variation of active and reactive power at sub synchronous and super synchronous speeds are also analyzed. Doubly Fed Induction Generator (DFIG) is used as variable speed generator. At super synchronous speed rotor can also deliver power to the grid thus can supply more than rated load without overheating. AC/DC/AC convertor is used with DFIG. Rating of convertor used in DFIG depends upon its maximum slip (/ 30%) , hence its rating is approximately one third of that would be used in Squirrel Cage Induction Generator . Control schemes for grid side convertor and rotor side convertor are discussed. Responses are obtained under different operating conditions.