Control of variable speed wind turbines: design task

Owing to concern over the environment, there is much interest in renewable sources of electrical power generation, of which one of the most promising is wind power. There are essentially two types of wind turbines, namely con stant speed and variable speed machines. In comparison to constant speed wi nd turbines, variable speed wind turbines are perceived to have several pot ential advantages which outweigh the considerable cost of the power electro nics required to realize variable speed operation. The two frequently menti oned ones are: additional energy capture below rated wind speed and additio nal power-train compliance and associated load alleviation above rated wind speed. The purpose of this paper is to investigate the design of the contr ol system (as opposed to the synthesis of the controller) for variable spee d wind turbines. The choice of control strategy is investigated and appropr iate realizations of the controller, to cater for the implementation issues of accommodation of variation in the plant dynamics over the operational e nvelope and switching transients, are identified. A thorough investigation of the dynamics and control of both stall regulated and pitch regulated var iable speed machines is undertaken.