Posts Tagged ‘Aerodynamic’

Leassons learned at Gotland University

February 15, 2011

From the last time I posted, we have learnt many things about the wind power industry. Here is a short summary of what we studied on this Master:

  • Principles of wind turbines: Components of wind turbines and the differences between synchronous and asynchronous generators must be known to understood the basic principles.
  • Climatology and Boundary Layer Theory: Kinetic energy from wind moves the blades, and thus electrical energy can be produced.
  • Aerodynamics: The shape and chord of blades are optimized by using formulas. Lectures provided by some accademics of Risoe and Uppsala universities were useful to understand these phisical principles.
  • Measurements Methods: Linear, non linear, CFD (Computational Fluids Dynamics) are useful to predict the wind resources at a determinated place by using MCP (measurement correlate and predict) techniques. Hence, software such as WindPro or WinSim are useful tools.
  • Wind Power potentials: Places located in cold climates or offshore wind farms have high potential in future but there are some considerations they must be valorated.
  • Grid Network: Before starting a new wind power project four words must be considered: Wind, wind, wind and infrastructure/grid network. Hence, it is important to know the point of common coupling (PCC) to connect the wind farm to the grid network.
  • Logistic: The other leg of the four words is obvious; roads, docks, and so on.
  • Public acepttance and environmental impact: Visual impact, flicker shadows, noises, consequences to the wildlife are other important aspects.
  • Policy and Legal Planning: Incentives and subsidiaries from administrations, legal frameworks… These frameworks can explain why some countries as Germany has such installed wind power capacity.

Brake Systems in Wind Turbines

July 12, 2010

According to quality parameters, DS472 (Danish Standard) and GL rules, wind turbines must have two independent braking systems. However, the IEC 61400-1 requirement does not specify what kind of two braking systems must have, but requires the protection system to remain effective even after the failure of any non-safe-life protection system component.

Usually, it makes sense to supply both aerodynamic and mechanical braking. Aerodynamic brake is more benign than mechanical braking, so it is always used in normal shut-downs. On the other side, although a braking system must be used during shut-downs, sometimes technicians allow rotor free turns (idle) within low winds. This strategy reduces the frequency of imposition of braking loads on the gear train.