A Simple Flexible and Robust Control Strategy for Wind Energy Conversion Systems Connected to a Utility Grid

Figure 7

Performances of the inverter side PI controllers in stand-alone mode. (a) d-axis load voltage reference (i), d-axis load voltage component (ii), and d-axis load voltage error (iii). (b) q-axis load voltage reference (i), q-axis load component (ii), and q-axis load voltage error (iii).

(a)

(b)