The necessity to solve global warming problems by
reducing CO2 emission in the electricity generation field had
led to increasing interest in microgrids (MGs), particularly those
containing the renewable sources such as solar and wind generation.
Wind speed fluctuations cause high variations in the output
power of a wind turbine which cause fluctuations in frequency
and voltage of the MG during islanding mode and originate
stability problems. In this paper, three techniques are proposed for
solving and reducing the consequences of this problem. In the first
technique, we develop a new fuzzy logic pitch angle controller. In
the second technique, we design an energy-storage ultracapacitor
which directly smoothes the output power of the wind turbine and
enhances the performance of the MG during the islanding mode.
In the third technique, storage batteries are used to support the
MG in the islanding mode.