Calculating transmission reliability margins based on statistical data

TenneT TSO GmbH has developed a new concept to calculate the transmission reliability margins (TRMs) on borders that are managed by using the available transfer capacity (ATC) approach. It is based on the identification of the relevant uncertainties of the capacity calculation process and a statistical analysis that is based on well-established methods. The concept is very versatile and in line with general guidelines for transmission system operators (TSOs) organized within ENTSO-E¹. This paper explains the incentive for TenneT to develop a new TRM concept, describes the new method in detail and compares it with the current practice.