بهره برداری از منابع باد متوسط ​​توسط سیستم های پمپاژ برقی بادی مستقل

A laboratory test rig has been developed, in order to analyse the mutual interaction of the different components of a low power WEPS, in the presence of arbitrarily chosen wind intensity. The performances with moderate wind speed of a system composed by a horizontal axis, fixed-pitch wind turbine, a synchronous generator and a centrifugal electric pump have been investigated, both at the start and under steady-state conditions. A control strategy of the alternator field voltage, which facilitates the starting of the pump in the presence of modest wind intensity and maximises average water discharge under any wind condition, has been defined, implemented on an electronic board and tested.

The use of low power Wind Electric Pumping Systems (WEPS) is extremely attractive for autonomous applications (without any electric buffer such as batteries or grid) in rural areas or isolated sites even if their wind resource is moderate, as they combine the main advantages of wind energy utilisation with the minimisation of its handicaps [1], [2] and [3]. The analysis of the performances of such WEPS architecture was carried out by the Department of Mechanical Engineering at the University of Calabria in collaboration with the CNR-CNPM (Milan) by means of field tests both in Calabria and in Sardinia [4], and the results were very satisfactory. The main weak point of the system was the starting up of the electric pump with modest wind intensity. The field tests, however, were unsuitable for investigating such behaviour in detail. A laboratory test rig has therefore been developed, in order to investigate the mutual interaction of the different components of a WEPS, in the presence of arbitrarily chosen wind intensity, both at the start and under steady-state conditions [5]. In particular, the influence of the alternator field voltage on the performance of the overall system has been analysed in detail. On the basis of this study, a control strategy of the field voltage, which facilitates the starting of the pump in the presence of modest wind intensity and maximises average water discharge in any wind condition, has been defined, implemented on an electronic board and tested.

A laboratory test rig, which enables the simulation of variable wind conditions, has been set up for analysing the mutual interaction of the components of a WEPS. The tests have shown that a configuration with a synchronous generator directly connected to the induction motor of a centrifugal pump is suited to moderate wind, but that submersible pump performances are strongly influenced by the control strategy of the alternator field voltage. In particular: 1. the standard field voltage regulator of a commercial alternator is not suited for a WEPS; 2. the starting up of the pump is facilitated by the weakening of the field voltage of the synchronous generator; 3. water discharge can be maximised by a field voltage, which increases proportionally to the rotational speed of the alternator; a new field voltage controller, therefore, has been implemented and tested, the results can be summarised as follows: 4. the starting up of the pump — which does not necessarily mean the beginning of water discharge — has been achieved even under very low wind conditions; 5. in the presence of low wind intensity and/or high geodetic heads, the proposed control strategy determines a considerable increase in water discharge of the WEPS in comparison with constant field voltage or standard output voltage control.