An interesting application note from our supplier Acromag - on how FPGA technology is assisting in energy
conservation with Wind Turbine Control.
Energy conservation is ever-growing in importance, both from
environmental and personal perspectives. Using less energy will preserve
resources and reduce consumer costs provided appropriate low-energy devices are
made available, reliable, and put into commonplace use. Successful green power
generation requires that: a) more power is produced than is consumed in
generating the power, and b) the mechanisms and control apparatus deployed
yield sufficient payback to recapture the overall investment made for
installation and a lifetime of maintenance. Field Programmable Gate Array
(FPGA) technology is currently playing a significant role in energy
conservation. Wind turbine control is just one application where PMC modules
with reconfigurable FPGAs are being used in renewable energy ventures.
The basic components of a control system to maximise energy
capture from a wind turbine include: rotor pointing, blade speed regulation,
minimisation of pointing and pitch control, and the mitigation of disturbances
(i.e. excessive rotor speed, wind gusts, etc.). See Figure 1. Additionally, the
environment inside the rotor head, or nacelle, is very hostile. Any control
device used in this environment must be self-diagnostic, rebootable, extreme
temperature tolerant, vibration tolerant, and of course, affordable. There are
many methodologies that will be or are currently being implemented. Many of
these approaches will share the basic control architecture components of
Acromag PMC FPGA modules provide a unique combination
well-suited to the application’s requirements. Conduction cooling and wide
ambient operating ranges help withstand the extremes temperatures. High channel
density with up to 97 single-ended I/O points on the front edge and up to 64
single-ended I/O points on the rear connector enables monitoring and control of
many components. Logic is stored in reprogrammable flash memory, available in
variable capacities, and is re-bootable at any time. The PMCs are able to generate
and monitor high speed serial communications. They can simplify the capture of
encoder and position feedback, as well as facilitate driving stepper motor
systems and closing servo loops. And finally, the capability to execute the
RTOS of choice on top of either a soft of hard PowerPC foundation makes the
selection of PMC FPGA modules very popular for wind turbine control and similar
green applications.
In Figure 2 above, the Setpoint would include items such as
the Target_RPM at which the rotor most efficiently generates power and any
boundary conditions (pitch, RPM, rate of movement for pitch and pointing
correction, etc.). Based upon wind speed and direction information from the
anemometer attached to the turbine head’s nacelle, it is possible to determine
the ideal Target_Pitch for the rotor turbine blades. The Pitch_Encoder data
provides present position information and the Pitch_Motor_Cmd is generated to
acquire Target_Pitch. Similarly, using wind direction information from the
anemometer, rotor pointing is adjusted for optimal use of the prevailing wind
source. Capturing sensory information, executing algorithms to maximise energy
capture, and generating commands to address circumstantially ideal rotor
pointing and blade pitch positioning are simple tasks for robust PMC FPGA
modules.
In fact, PMC modules, such as Acromag’s PMCVFX70 with a
Virtex-5 FPGA and PowerPC core can be solely tasked to this undertaking in
standalone configurations. No in-rotor or in-nacelle computer is required.
For further information about the Acromag product range in
Australia & New Zealand, please contact
Acromag (all other countries) +1 248-624-1541
