Environmental Engineering Reference
In-Depth Information
There is no uniquely correct way forward as yet, and more work is required.
In relation to wind generators, and DFIG devices in particular, there is a lack of
information at the time of writing as to their responses to single-phase faults. They
are likely to make some short-term fault contribution, but then trip rapidly as a
result of unbalanced phase currents.
In order to operate a system successfully with high levels of wind penetration, real
time information is required. To manage energy demand, wind farm output and
wind speed/direction will need to be reported every few minutes. There will also
need to be some instruction and status signals related to whether reserve is being
provided and the amount of reserve available. Network remedial action schemes
may need to be informed as to the output of one or a group of wind farms. Voltage
control schemes are likely to require information on the voltage at wind farms and
the farm's reactive power generation/absorption of MVAr in real time. Instructions
for the voltage control system and target may need to be given remotely and alarms
sent when out-of-limits control is in operation or an emergency trip is operated.
Wind farm status reports need to include, as a minimum:
down - lack of wind
down - on instruction or pre-gust control
down - maintenance
running free
running curtailed
How this is best managed is still to be explored. Some experts believe that
instruction and information from a wind farm controller is all that is required and
that all subsidiary intelligence rests at the wind farm. Others believe it safer to draw
information directly from each turbine. Possibly a hybrid will emerge which
satisfies both the security and efficiency criteria. Whichever method is adopted will
have to be interfaced with a range of supervisory, control and data acquisition
(SCADA) and energy management systems (EMS). Protocols differ, but, partly
because information exchange has proven difficult during major system incidents,
common interfacing packages are emerging.
Performance assessment and model trimming require disturbance recorders
with a sampling rate of typically 20 kHz, and, where practicable, remote reading
and resetting facilities.
4.9.1 System protection
The standard of protection increases with system importance. Thus a simple car-
tridge fuse may be used to protect an LV circuit whereas dual main protection
Search WWH ::

Custom Search