Wind turbine control

Wind turbine systems and methods are provided. The wind turbine system includes a plurality of coaxial, counter-rotating turbine assemblies. First and second shroud assemblies define a generally spherical volume containing the first and second turbine assemblies. The first and second shroud assemblies each include a shroud member that is controlled in response to information from a wind sensor to selectively shield or expose portions of the respective turbine assemblies to the wind by changing the rotational position of the shroud members about the system axis. The turbine assemblies are interconnected to a generator for the production of electrical power.