Frequency Control Issues in Power Systems: the Effect of High Share of Wind Energy

Technological advances, low production costs, efficiency, emission-free operation, and abundance of supply are some of the factors that have strongly motivated the use of renewable energy sources for electrical energy production in recent years. The economy of scale has placed wind generation well ahead of other renewable technological alternatives, a fact that is reflected in the significant increase in operating units in many power systems. However, the inherent characteristics of wind such as: natural intermittence and non-dispatchability, might negatively impact the power system performance in terms of frequency stability by reducing the inertial resources as well as the regulation capability. This paper presents a comprehensive analysis of power system frequency control issues, its theoretical basis, and time-domain simulations that illustrate each of the electromagnetic and mechanical phenomena involved. Additionally, a methodology for evaluating the minimum amount of inertial resources in a power system, so that the frequency response complies with a given grid code under various wind penetration scenarios, is proposed. Finally, the proposal is assessed by performing time-domain simulations in MATLAB/Simulink® using two approaches for representing the behavior of the power system: the detailed modeling of the components and the load frequency control scheme.