Electrical Systems of a Grid Connected 2 MW Mini Hydro Power Project at Siripagama

Abstract

This paper presents the electrical system design of a 2MW Mini Hydropower Power Plant (MHPP) project at Siripagama. Catchments area of 19.1 km2 and annual average rainfall of 3935 mm yield to 3.5 m3/s designed flow. Net head was found as 68 m. Plant was sized to 2 MW and accordingly structural components and electro-mechanical system were designed. Two numbers of electro-mechanical units in which each unit consists of Francis turbine of 1054 kW, synchronous generator of 1250 kVA, 400 V and two number of 33 kV 1800 kVA step up transformers. The generator systems were modeled using PSCAD simulation package to check the performance of generator. Also the system together with the transformer was studied during the normal loading and load rejection operations. Grid interconnection lines were modeled using SYNERGEE software. This was used to study the line flows and voltages in the feeder from Ratnapura grid substation to the Siripagama MHPP. The simulation results confirm the proper operation of the MHPP and the grid without violating the limits of voltage and conductor ratings. Finally the total system was commissioned on 19th June 2006. Initially the plant factor was about 36% and in October it rose to 56%. This is one of the projects, which confirmed the better performance of the micro hydro plant in Sri Lanka.