The critical factor is how much power your turbine can produce. If its output is low, the chances are the inverter will never run anyway. How is it all connected, your optimal solution would be to use the wind turbine to produce DC for your inverter, possibly with a battery bank for extra storage, and the inverter to be grid tied to incoming line AC. That way you benefit most from the turbine even if the Leaf isn't on charge.
Most grid-tied inverters have a data port that let you read their current input and output powers, you should be able to use it to produce your own disconnect circuit that breaks the AC to the charger when the output is below a threshold.
Brian.