The performance analysis of a pico-hydro pump as turbine power plant

Abstract

Hydropower plant is a type of green technologies to generate electricity. One type of hydropower plants is Pump as Turbine (PAT), an economical alternative to building a power plant with small flow water (pico-hydro). The working principle of the PAT is by reversing the pump working. At PAT, the water flow enters the pump in the discharge section and exit through the suction section of the pump. Centrifugal pump is one type of pumps suitable for use as PAT. The motor from the centrifugal pump can be converted into a generator by replacing the magnetic shaft of the stator. The implementation of PAT was performed on Cibalok Waterfall, with a height of 2.5 m and a water flow of 31.915 L/sec at 70 cm water level. Grundfos NF 30-18 centrifugal pump was used at the implementation. Two models of impellers and two water inlet conditions were tested for comparison. The first model of the impeller was the original impeller from Grundfos NF 30-18 with steel metal material. The second model of the impeller was a modified impeller with a brass metal material. Meanwhile, the two water inlet conditions were a single inlet with a 4-inches diameter and an inlet with two 4-inches pipes. The experiments show that compared to the second model of the impeller, the first model of the impeller with two inlets of 4-inches pipes generated maximum water flow-rate, rotation speed and electrical power at 2.42 L/s, 1134.9 rpm, and 12.05 W, respectively.