To facilitate the increase in the penetration of renewables in the powers systems, this thesis aims at alleviating the concerns raised for the frequency control schemes as a result of integration of renewables to the grid including the increased rate of change of frequency (ROCOF), larger frequency deviations that might endanger the frequency stability, lower frequency quality and the increased wear and tear of the generating units participating in frequency control. Proper indices are introduced to quantify these performance criteria. It has been shown that, when the voltage of the buses does not experience large deviations after the disturbances, the frequency response model (FRM) can accurately calculate all the performance indices except ROCOF. However, large voltage deviations reduce the accuracy of FRM in calculating all the performance indices. A simplified network preserving () model has been proposed in this thesis for calculating the performance indices; especially ROCOF. To rise to the aforementioned challenges, increasing the inertia of the grid through a combination of virtual inertia and synchronous condensers and incorporating loads in frequency control have been suggested in this thesis. Two control schemes are proposed for the coordinated participation of loads together with generating units in frequency control. Determining the parameters of these control schemes has been defined as optimization problems with proper objective functions and constraints. It has been shown that using the control parameters obtained by solving these problems, the proposed methods can achieve the determined objectives. Keywords: Demand response, Frequency stability, Multi-objective optimization, Power system modeling, Renewable energy resources, Virtual inertia, Wear and tear of generating units.
