Small Wind Electric Systems Wind Turbine Electrical Output – Electricity from a spinning shaft Balance of Systems – Types – Components
First Things First. What does a small wind turbine produce? Wild Alternating Current (Wild AC) – “Wild” due to the fluctuating voltage, current and frequency. – Why is this? Most modern small wind turbines are direct drive permanent magnet systems (there are exceptions) – In most cases the wild AC needs to be rectified. Conversion of Alternating Current (AC) to Direct Current (DC) WILD ACDC Hz
Electricity from a Spinning Shaft Click Here for Animation
Why Alternating Current? Simplicity of permanent magnets alternators This AC power is rectified to Direct Current regardless of battery or grid-tie configuration. 3 phase output is most common
Why Three Phase? Most effective use of space and materials!
Axial Flux PM Alternators
Small Wind Systems Small Wind Systems: Battery (off-grid) systems Grid-Tie with battery backup systems Batteryless / Direct grid-tied systems Direct Drive Batteryless Systems
Battery (off-grid) systems Regulation and Conversion
Battery (off-grid) systems Controller
Off-Grid Hybrid System Combines multiple DC charging systems
Battery (off-grid) Hybrid system Controller
Benefits of Hybrid Systems? Wind and solar compliment one another! JanFebMarAprMayJunJulAugSepOctNov Dec Hours of sunshine or average wind power (Watts/m 2 ) Average wind power Data from SE Iowa Hours of Sunshine
PV modules and wind turbine (no generation) Battery (storage) Loads (utilization) PV modules and wind turbine (active generation) Summer Winter Battery (storage) Loads (utilization) The Effects of Seasons on Hybrid Power Systems
Grid-Tie with Battery Backup Controller
Grid-Tie with Battery Backup Benefits: – Potential sale of excess energy – Battery backup during electrical grid failure – Incentives supported Downfalls: – Expensive – Added maintenance (batteries)
Batteryless / Direct Grid-Tie Systems Controller
Benefits: – Sale of excess energy to the grid – Lower system cost – Incentives supported Downfalls: – No battery back up. If the grid fails you are left in the dark.
Direct Drive Batteryless System Controller
Benefits: – Simplicity – Lowest in cost (no balance of system needed) Downfalls: – Only power loads when resource is available – Heating applications require large turbines