WATER DELIVERY MAXIMISATION IN AUTONOMOUS WIND ELECTRIC PUMPING SYSTEMS

The paper presents the results of an experimental optimisation of the overall performances of an isolated Wind Electric Pumping System. In the considered WEPS the wind turbine drives a synchronous generator which is directly connected to the asynchronous motor of a 1 kW multi-stage submersible centrifugal pump. The system has therefore no electric buffer so that both the alternator and the pump run at variable speed and the generated electric energy in characterised by variable voltage and variable frequency. The analysis of the data shows that the excitation voltage of the synchronous generator can be conveniently used as control variable for both facilitating the start of the electric pump and maximising the water delivery once the pump is running. A control strategy, based on the measure of the alternator frequency only, has been implemented and tested both in steady-state conditions and with variable wind speed and the results have shown a remarkable increase in the average water delivery of the system.