IN Norway, the potential for large scale generation of wind
power is huge, but the impact of the wind generation on the
power system will no longer be negligible if high penetration
levels are going to be reached. The extent to which wind power
can be integrated into the power system without affecting the
overall stable operation depends on the technology available to
mitigate the possible negative impacts such as loss of generation
for frequency support, voltage flicker, voltage and power
variation due to the variable speed of the wind and the risk of
instability due to lower degree of controllability.
Many countries in Europe and other parts of the world are developing
or modifying interconnection rules and processes for
wind power through a grid code [1], [2]. The grid codes have
identified many potential adverse impacts of large scale integration
of wind resources. The risk of voltage collapse for lack of
reactive power support is one of the critical issues when it comes
to contingencies in the power system. Closely linked to this is
the low voltage ride through (LVRT) capability, which is one
of the most demanding requirements that have been included in
the grid codes. The LVRT requirement, although details are differing
from country to country, basically demands that the wind
farm remains connected to the grid for voltage dips as low as
5% retained voltage [3]. The Nordel grid codes have adopted
the LVRT profile shown in Fig. 1 for recommendation in the
Nordic region [4].