Continuous drive of non-constant power load such as pump by two induction machine system utilizing solar energy

摘要

In order to make use of solar energy instead of oil and coal, the authors have proposed a new pumping system which is composed of two coupled induction machines with a photovoltaic array. One induction machine is driven by electric power of the photovoltaic array through a general purpose inverter and the other induction machine is interconnected to the utility line. This system can generate a desired mechanical power and supply the surplus electric power of the photovoltaic array to the utility line. In this paper the proposed two induction machine system is taken into consideration to drive the pump load for circulating water. As the power of this load is non - constant with respect to rotational speed, the inverter frequency is newly formulated in order to get the desired mechanical power while utilizing the maximum power of the photovoltaic array. And the variation of the rotational speed is estimated as a function of the fluctuating solar power. It is shown from experiments that the two induction machine system can continuously drive the volute pump even in a variable flow of water and fluctuating insolation.