Technical and regulatory exigencies for grid connection of wind generation

Abstract

Pollution problems such as the greenhouse effect as well as the high value and volatility of fuel prices have forced and accelerated the development and use of renewable energy sources. In the three last decades, the level of penetration of renewable energy sources has undergone an important growth in several countries, mainly in the USA and Europe, where levels of 20% have been reached. Main technologies of renewable energies include wind, hydraulic, solar (photovoltaic and thermal), biofuels (liquid biodiesel, biomass, biogas), and geothermal energy. Within this great variety of alternative energy sources, wind energy has experienced a fast growth due to several advantages, such as costs, feasibility, abundance of wind resources, maturity of the technology and shorter construction times (Ackermann, 2005). This trend is expected to be increased even more in the near future, sustained mainly by the cost competitiveness of wind power technology and the development of new power electronics technologies, new circuit topologies and control strategies (Guerrero et al., 2010). However, there are some disadvantages for wind energy, as wind generation is uncontrollably variable because of the intermittency of the primary resource, i.e. the wind. Another important disadvantage is that the best places to install a wind farm, due to the certainty and intensities of suitable wind, are located in remote areas. This aspect requires of additional infrastructure to convey the generated power to the demand centres. Unfortunately, in several countries the regulatory aspect does not follow this fast growth of wind possibilities. Many countries do not have specific rules for wind generators and others do not make the necessary operating studies before installing a wind farm (Heier, 2006). Power system operators must consider the availability of these power plants which are not dispatchable and are not accessible all the time. Today, developing countries, such as Argentina, are subjected to an analogous situation with wind energy, having perhaps one of the best sources of such energy around the world. Nowadays, there are several operative wind farms and others in stage of building and planning. Similar to other countries, in Argentina there is a lack of regulatory aspects related to this topic (Labriola, 2007). This chapter thoroughly presents a revision of wind generation, including the following sections. In the first part, a brief history of the wind energy developments is presented. Following, some remarks related to the modern wind energy systems are made. Then, a survey of modern structures of wind turbines is carried out, including towers and foundations, rotor, nacelle with drive train and other equipment, control systems, etc. Subsequently, major wind turbine concepts related to fixed and variable speed operation and control modes are described. Eventually, technical and regulatory exigencies for the integration of wind generation into the electrical grid are discussed in detail, including a study of selected countries grid codes.