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Abstract
T
Wind generation is becoming an important part of the generating capacity of the
modern utility grids. The wind farm protection system is usually divided into
different protection zones including the wind farm area, wind farm collection
system, wind farm interconnection system and the utility area. The medium voltage
collector feeder in a wind farm is usually protected by conventional protection
strategy. The conventional protection scheme suffer from some drawback such as
inability to discriminate between faults occurring at wind turbine generator (WTG)
and faults occurring at the medium voltage cable. It also suffers from inability to
isolate faulty cable from WTG side i.e. WTG is feeding the fault.
The above mentioned drawbacks can be alleviated using the new proposed
protection schemes. Two new protection schemes have been used in this thesis.
The first scheme is based on directional angle and discrete wavelet transform
(DWT) algorithms. This scheme is convenient for small WTG with capacity less
than 1MVA. It uses the voltage and current signals to achieve the protection of
single feeder. Any fault occurs at any parallel feeder and power grid is considered
external fault. The second scheme is based on differential current and directional
angle. This scheme is suitable for WTG with capacity greater than 1MVA and is
used to protect the whole feeders in the wind farm since the medium voltage cable
in this scheme is divided into several zones.