Wind Penetration Limited by Thermal Constraints and Frequency Stability

With the increase of wind generation in the United States it is important to determine the ability of a transmission system to handle large increases in wind power. This subject needs to be studied from both the steady state and dynamic issues related to wind generation. This paper provides a process to determine the transmission capacity of an existing transmission system, based on thermal limitations and a steady state analysis. Next, the paper develops the concepts behind the modeling of wind turbines particularly as they are related to the frequency stability of the power system. A comparison of fixed speed generator (FSG) wind turbine and doubly-fed induction generator (DFIG) wind turbines is performed in terms of inertial response capabilities, a key issue in frequency stability. Finally, an example is provided in the form of a set of simulations, measuring the frequency response of FSG´s and DFIG´s.