Permanent magnet wind generators: control strategies to manage voltage unbalances

The paper presents four different control strategies for grid connected voltage source inverters, devoted to the interface of permanent magnet synchronous wind generators with the distribution network. A common dq-axes control is compared with two modified controls in the dq frame which take into account also negative sequence components of voltages, and currents and a control approach in the stationary αβ frame which reduces the computational complexity of the control itself. An ATPDraw model of a 2 MW wind generator has been developed and employed for simulating the responses of the four control schemes to voltage unbalances and voltage dips. The improved control strategies have shown better performances in terms of reduction of 100 Hz oscillating power components during network voltage unbalances.