  Pulsar wind nebulae (PWNe) have been established as the most populous class
of TeV gamma-ray emitters. Since launch, the Fermi Large Area Telescope
(LAT)identified five high-energy (100MeV <E< 100 GeV) gamma-ray sources as
PWNe, and detected a large number of PWNe candidates, all powered by young and
energetic pulsars. The wealth of multi-wavelength data available and the new
results provided by Fermi-LAT give us an opportunity to find new PWNe and to
explore the radiative processes taking place in known ones. The TeV gamma-ray
unidentifiedsources (UNIDs) are the best candidates for finding new PWNe. Using
45 months of Fermi-LAT data for energies above 10 GeV, an analysis was
performed near the position of 58TeV PWNe and UNIDs within 5deg of the Galactic
Plane to establish new constraints on PWNe properties and find new clues on the
nature of UNIDs. Of the 58 sources, 30 were detected, and this work provides
their gamma-rayfluxes for energies above 10 GeV. The spectral energy
distributions (SED) andupper limits, in the multi-wavelength context, also
provide new information on the source nature and can help distinguish between
emission scenarios, i.e. between classification as a pulsar candidate or as a
PWN candidate. Six new GeV PWNe candidates are described in detail and compared
with existing models. A population study of GeV PWNe candidates as a function
of the pulsar/PWN system characteristics is presented.
