Analysis of Series-DC Offshore Wind Plants with Aerodynamic Wake Effects

In series-dc wind plants, variations in power output among turbines due to aerodynamic effects may lead to violations of operational limits of electric machines and power electronic converters. Turbine wakes constitute the predominant cause of such variations. It is, therefore, imperative to incorporate wake models during analysis of wind plant-level issues and control strategies. In this paper, two candidate energy conversion configurations previously proposed for series-dc connected turbines are considered. They are analyzed in the context of a notional offshore wind plant using the Jensen wake model. An optimization problem is formulated for maximizing total plant power output. A key finding is that this objective is attainable without any turbine violating operational limits for arbitrary wind direction and speed. This, however, may require variation of transmission voltage or current as a function of prevailing wind conditions by means of the onshore converter interfacing the plant with the terrestrial power grid.