Interaction of Large Wind Power Generation Plants with the Power System

This paper surveys the impact of increasing level of wind generation on the performance indices of the interconnected system and what this entails in terms of improved control and protection schemes for wind turbines. After a brief review of the mathematical model of the doubly-fed induction generator (DFIG) and its control structure, simulation results are shown to quantify the effect of wind generation on system frequency, voltage profile and behavior during a short-circuit. The results were correlated with the outcome of a recent more comprehensive study. This study carried out by a consortium of major German utilities and research institutes summarised the experiences to-date with existing wind plants and worked out the necessary modifications on the existing grid code, which stipulates conditions for connection of wind farms to the high voltage grid. The paper then discusses some of the proposed major changes and extensions that include fault ride-through, voltage profile maintenance and the need for voltage control, system monitoring and protection as well as retrofitting of older units. The new requirements are defined taking into account some new developments in wind turbine technology, which should be utilized in the future to meet the enhanced grid requirements.