Flexibility of the power system: background, relevance, and categorization

The definitions of flexibility and the place of flexibility in the structure of the main general properties of energy systems are given. The factors and trends are indicated, which determine the appearance of current energy systems, and even more future energy systems. The emerging trends will require a revision of the principles and means of power system management and control towards increasing the flexibility. Based on these factors, it is possible, firstly, to analyse flexibility as a complex property, using differentiation by aspects and categories, and, secondly, to determine and categorize the means of ensuring flexibility. The paper concludes with the European energy regulators' view of flexibility as a marketable service