Implementation of a Methodology to Define the Optimum Capacity of a Wind Farm.

Abstract

The seasonality and variability of the windregime cause the wind farms to operate during a significant partof time in partial load regime and sometimes with very low loadfactors. In Portugal, the permission to the connection to theelectrical grid is given in terms of nominal power.Consequently the installable capacity is limited and theproductive capacity is only used during a reduced number ofhours per year.

Even installing a bigger capacity then the grid limitation, onlyin small periods the power output would exceed that value. Itshould then be necessary to shut down some of the turbines or,by any mean, to limit the output of the wind farm. In return,during large periods, the excess in capacity will permit toincrease the energy production and the wind farm income.

The determination of the periods when the wind farm loadimposes that one or more turbines should be shut down is notevident, when studying wind farms operating in complex terrainsites. In these regions, the load of each wind energy converterwill vary according to the wind velocity and orientation, beingusual to find large differences of load factor over shortdistances.

Furthermore, the determination of the optimum capacity inthese situations cannot be separated of the investment costs ofincreasing the nominal power installed. An economical analysishas to be associated to the productivity calculations, in order todetermine the ideal solution from the project economicalperformance point of view.

This work presents a test case based in a methodologydeveloped to support the project optimization of wind farmswith limitations in the power to be delivered to the grid.