Computations on the Frenchtransmission grid in order to improvethe voltage security assessment

Abstract: As the electric consumption increases and the investments are hard to make, electricitynetworks are operated closer to their limits. In such conditions, a generator or a transmissionline outage can have tremendous impact, leaving a great number of people without electricity. Itis therefore a matter of prime importance to ensure power system security and in particularvoltage stability. Static criteria used in on-line simulations as well as protection and defensedevices such as load-shedding devices play a critical role for voltage stability and are thus crucialfor the network security. The core of this project is to determine efficient tools to detectundesirable conditions in operational context and to determine a pertinent activation level foran automatic load-shedding device used for the system protection against voltage instability.In the first part of this report, theoretical background regarding voltage stability ispresented, followed by the software and methodologies used during the Master’s thesis work.The second part of this report focuses on case studies conducted for the French powersystem. From an initial objective of updating static criteria, the results have actually led to thewithdrawal of these criteria and a switch to dynamic simulations for the North-East and Eastareas, as well as to the improvement of Astre software database. Simulations on the moststressed conditions from last winter allowed the updating of the activation level for theautomatic load-shedding device. These changes have been validated and will be applied forvoltage security assessment of the French network in the future.