Analysis of the Implementation of the Primary and/or Inertial Frequency Control in Variable Speed Wind Turbines in an Isolated Power System with High Renewable Penetration. Case Study: El Hierro Power System

Abstract

With high levels of wind energy penetration, the frequency response of isolated powersystems is more likely to be affected in the event of a sudden frequency disturbance or fluctuatingwind conditions. In order to minimize excessive frequency deviations, several techniques and controlstrategies involving Variable Speed Wind Turbines (VSWTs) have been investigated in isolated powersystems. In this paper, the main benefits and disadvantages of introducing VSWTs—both their inertialcontribution and primary frequency regulation—in an exclusively renewable isolated power systemhave been analyzed. Special attention has been paid to the influence of the delays of control signalsin the wind farm when VSWTs provide primary regulation as well as to the wind power reservevalue which is needed. To achieve this objective, a methodology has been proposed and appliedto a case study: El Hierro power system. A mathematical dynamic model of the isolated powersystem, including exclusively renewable technologies, has been described. Representative generationschedules and wind speed signals have been fixed according to the observed system. Finally, in orderto obtain conclusions, realistic system events such as fluctuations in wind speed and the outage of thegeneration unit with the higher assigned power in the power system have been simulated.