Aerodynamic and electrical evaluation of a VAWT farm control system with passive rectifiers and mutual DC-bus

A wind farm with a simple electrical topology based on passive rectifiers and a single inverter (mutual topology) is compared to a more complex topology where each turbine has a separate inverter (separate topology). In both cases, the turbines are controlled electrically by varying the extracted power with the rotational velocity as control signal. These two electrical topologies are evaluated with respect to the absorbed power for a farm of four turbines placed either on a line or in a square configuration. The evaluation is done with a vortex model for the aerodynamics, coupled with a model of the electromechanical system. Simulations predict that individual control is beneficial for aerodynamically independent turbines if the wind speeds differ significantly between the turbines. If the differences in wind speed are caused by one turbine operating in the wake of another, the deviations in power output between the topologies are less prominent. The mutual topology can even deliver more power than the separate topology when one turbine is in the wake of another turbine if the wind speed changes rapidly.