Autonomous water pumping system based on wind generation. Control by rotor frequency

There exists in Argentina a growing interest in alternative energy sources such as wind and solar energy for water pumping in remote areas. In this context, the main objective of the paper is to present and evaluate a configuration for an autonomous wind energy conversion system oriented to water pumping. It consists of a wind turbine with a wound rotor generator, electrically coupled with a squirrel cage induction machine moving a centrifugal-type water pump. The power flow control is performed through the rotor winding of the generator by changing the frequency and voltage of its excitation. The system is controlled by means of a torque control which follows the optimal turbine torque in order to maximize the volume of water pumped based on the optimization of the wind energy capture. The energy injection from a secondary energy source to DC-link is also foreseen, in such a way that the pump could absorb both power sources. An analysis of the system operation points and the power flow for different wind speed and solar radiation is accomplished, supported by simulation results.