Pump-as-turbine (PAT) for small scale power generation: A comparative analysis

Pumps can be operated as turbines to generate electricity by changing the mode of its operation and reversing the direction of power flow. Since the pump manufacturers usually do not provide datasheet showing the pump´s characteristics and performance when operating as turbines, problem arises as to understand how the pump behaves in the turbine mode or reverse running mode. To resolve the problem scientists have developed different mathematical models to find the pump behavior in the turbine mode and its characteristics. In this paper, the BEP (best efficiency point) of a pump operated as turbine (PAT) turbine is mathematically determined using two different methods with the help of the experimentally obtained general pump characteristics data. The BEP is then used to determine the amount of hydraulic power and hence in turn the amount of electrical power that can be generated when an induction machine (operated in generator mode) is coupled to the pump. Also a suitable site is assumed to determine the operating points or range of the PAT using the conventional mathematical models available in many literatures of fluid mechanics.