Posts Tagged ‘Generators’

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.

Power Quality Standards.

July 13, 2010

Voltage provided by Wind turbines must comply some requirements specified in the IEC 61400-21 standard. Here we are some power quality parameters that power energy from wind turbines must be under control:

Rated Data

  • Rated Power (Pn) (or Active Power): Maximum continuous electric output power for a wind turbine under operating conditions.
  • Rated Reactive Power (Q­­­­­n): Reactive power under rated power, nominal voltage and frequency.
  • Rate Apparent Power (Sn): Apparent power from the wind turbine while operating at rated power and nominal voltage and frequency.
  • Rated Current (In): Current from the wind turbine while operating at rated power and nominal voltage a frequency.


Generators in Wind Turbines.

July 9, 2010

Basically, any type of three-phase generator could work in a wind turbine but they must fulfill some requirements. We have just classified them according to their generator type and the coming prototypes that nowadays we are studying. This post, as the last one, is a summary from the book Wind Power in Power Systems (Chapter 4) by Thomas Ackermann. However, for any further information, this link can be interesting.

Asynchronous (Induction) Generator.

It is the most numerous in wind turbines. Advantages: Robustness, mechanical simplicity, low price. Disadvantages: It has to receive an exciting current from another source and consumes reactive power (so, reactive power is supplied by the grid or by a power electronic system).


Types of Commercial Wind Turbines.

July 8, 2010

We already saw the different wind turbines we can find nowadays, from the HAWT to VAWT. However, the most commercial at this moment are the High Tip Speed Ratio HAWT. In this post, we are going to describe the different models of wind turbines and what kind of technology they use to convert the mechanical energy to electric energy.

If we pay attention at the above table, we can see there are two wind turbines models according to their Speed Control and Power Control. Thereby, we can find four models: Type A, Type B, Type C, and Type D (see the below diagram). There are three variants for the Type A (A1,A2 and A3). Although it would be possible to manufacture the same variations for the B, C and D Types, it would be not worthy (from the commercial point of view) because these models lack the capability for a fast reduction of power (see the grey-colored boxes in the first diagram). Let´s start describing the possibilities to control the power the aerodynamic forces on the turbine rotor.