Environmental problems like increasing concentration of CO2 in
the air, global warming and various problems that are arising due
to insufficiency in fuel energetic resources can be alleviated using
renewable large scale electrical power producing energy resources
such as solar, wind and tidal etc. [1–5]. Among all, wind power has
scientifically proven to be the most promising source for generation
of electricity with least environmental impact [3]. In case of
wind energy system, the aerodynamic energy in the form of kinetic
energy of the wind gets converted to clean electrical energy
through a proper technical arrangement of a wind turbine (WT)
and an induction generator [6]. The induction generator used
may be of fixed-speed type or variable speed type. The mostly used
variable speed type induction generators are the Doubly-Fed
Induction Generators (DFIGs) [2].
DFIGs are preferred due to the advantages of using reduced size
(25–30%) power converters, implementation of power factor control
at a minimal cost and the four quadrant converter operation
which makes it similar to that of a synchronous generator. It has
the unique ability to generate power both in sub-synchronous as
well as super-synchronous regions of rotor speed [6]. To maintain
the operability along with reliability and power quality of the grid,
Wind Energy Conversion Systems (WECS) are integrated with the
power grids rather operating standalone. But prior to grid integration,
the WTs must meet the technical standards implemented by
most of the power system operators known as ‘‘grid codes”. The grid
code requirements are of two types: static and dynamic requirements.
Static requirements include steady state behaviour and
power flow at the point of common coupling (PCC) whereas
dynamic grid code requirement includes the desired responses of
the induction generator during grid disturbances [7–9]. These
requirements include the operating range of voltage and frequency,