**Preface to "Symmetry in Renewable Energy and Power Systems"**

The study of power systems is closely related with symmetry. For example, multiphase power systems are inherently symmetric. The study of symmetrical and asymmetrical faults in power systems is a critical issue. The phase sequence arrangements of multicircuit overhead lines on the same tower directly affects the symmetry of power transmission systems, which influences the operation of power grid and relay protection. Moreover, symmetry is a topic of intensive investigation in the analysis of grid interconnection, including symmetrical and asymmetrical network parameters in smart grid infrastructures. In renewable energy, the symmetry is present in the layout of wind power plants or photovoltaic plants, among others, while the performance of solar systems can differ if they are used with symmetric and asymmetric concentrating CPC collectors. Therefore, investigations related to symmetry in power systems and renewable energy will favor the advance in these disciplines.

> **Ra ´ul Ba ˜nos Navarro, Alfredo Alcayde** *Editors*
