The impact of large scale wind power generation on power system oscillations

Increasing amounts of wind turbines are connected to electrical power systems. This affects many aspects of their operation and behaviour. In this paper, the impact of large scale wind power generation on power system oscillations is treated. The three main types of power system oscillations, namely oscillations of a group of generators against a strong system and intra- and inter-area oscillations are studied. To this end, test systems are used. The effect of wind power on the oscillations is investigated by gradually replacing the power generated by the synchronous generators in the system by power from either constant or variable speed wind turbines, while observing the movement of the eigenvalues through the complex plane. From the results, it is concluded that the effect of wind power on power system oscillations depends on the wind turbine concept (constant or variable speed) and on the wind power penetration. In most cases, an increase in frequency and damping of power system oscillations was observed. This observation is caused by a relative reduction in size of the synchronous generators that engage in power system oscillations, which is equivalent to strengthening their mutual coupling. Further, it was shown that constant speed wind turbines damp power system oscillations more than variable speed turbines. This is caused by the damping effect of the squirrel cage induction generator used in constant speed wind turbines. (C) 2003 Elsevier Science B.V. All rights reserved.