Maximum power point tracker

wind turbine maximum power point tracker

I'm designing a maximum power point tracker (MPPT) specifically optimized for wind turbines.

Currently available off-the-shelf MPPTs work fine in the application they were designed for. (See wikipedia: maximum power point tracker for details). However, apparently they won't work with wind turbines. When they pull the maximum instantaneous power from a spinning turbine, the turbine blades go slower and slower until it stops, at which point you're getting zero power out.

The wind turbine maximum power point tracker I'm designing will extract more energy over the course of a day than those MPPTs. Instead of pulling the current that maximizes instantaneous power out, it will pull somewhat less current in order to keep the blades spinning at the optimum speed. The optimum speed will change over the course of the day as the wind speed changes.

--DavidCary 08:14, 26 September 2008 (PDT)

I've considered 2 possible strategies:

(a) keep the blades spinning at the optimum speed, the speed that gives the maximum power out at the current wind conditions. The wind turbine acts as a base load power plant, in the sense that the amount of power it supplies is independent of the load.

When using this strategy "a" with off-grid systems tied to a battery, when some device (say, a cordless drill) needs a quick burst of energy -- more power than the wind turbine is currently generating -- supply that energy from the batteries.

(b) When there is low load, let the blades spin up slightly faster than the optimum speed. When some device (say, a cordless drill) needs a quick burst of energy -- more power than the wind turbine is currently generating -- supply that energy from by pulling *more* power from the wind turbine, temporarily slowing it down. The wind turbine acts as a peaking power plant.

This strategy "b" uses the spinning blades as a form of flywheel energy storage.

Which strategy is better for battery-less grid-tied wind turbines? Which strategy is better for off-grid systems with battery backup? --DavidCary 11:33, 27 September 2008 (PDT)

Online Resources

• How to Build Your Own SD-100 MPPT - Schematic & Instructions on how to build your own
• Red Rock Energy: Maximum Power Point Trackers