Contents lists available at ScienceDirect Electric Power Systems Research journal homepage: www.elsevier.com/locate/epsr Grid operation-based outage maintenance planning Guillaume Crognier, Pascal Tournebise, Manuel Ruiz ⁎ , Patrick Panciatici RTE - Réseau de Transport d’Electricité, Paris La Défense, France ARTICLE INFO Keywords: Energy transition Maintenance Planning Risk ABSTRACT The increasing integration of renewable energies in the French electricity network leads to important changes in its operation, resulting in new grid constraints. Besides, some maintenance tasks on the overhead power lines are live-line works, and others require a planned outage. Such interruptions may not be feasible with a renewables- driven grid operation. As a consequence, current maintenance planning methods might not be relevant in the future. In particular, they have to take into account the risk implied by performing maintenance when having a high proportion of renewables in the grid. This work presents a three-step approach for tackling this issue. First, risk values corresponding to diferent future scenarios are computed, using the (N-1) security assessment. Second, these computed values are included in several optimisation approaches in order to fnd a good schedule. Eventually, a third step validates the obtained planning. 1. Introduction Guaranteeing both electricity delivery and supply is one of the most important mission of a transmission system operator such as RTE. But such an objective can be carried out only if the grid is correctly main- tained. In particular, some maintenance operations on the overhead power lines are live-line works while others require to shut the power down. When this happens, both electricity delivery and supply have to be guaranteed, meaning that maintenance operations have to be planned carefully. Indeed, the security of a grid is by defnition its ability to survive contingencies [1]. When there is not any maintenance operation, the (N-1) security assessment rule makes the network re- silient to an unexpected contingency [2]. However, if several break- downs are to occur the grid might face major blackouts [3]. In this context, planned outages due to maintenance work have to be sched- uled with extreme caution. Alongside with this very operational aspect, anticipating what maintenance plannings will look like in the years to come helps in designing efcient network design strategies. If future maintenance operations appear to be unfeasible due to an aging network, new gen- eration and consumption plans or even the energy transition, RTE has to anticipate these changes and adapt its current maintenance practices and design, as of today, new strategies. In the literature, ”outage planning” often refers to the maintenance of the generation units [4,5], even if occasionally more specifc grid constraints are taken into consideration [6,7]. Finally, some studies were conducted in order to fnd optimal outage schedules for both generating units and transmission networks [8–11]. As RTE is an electricity transmission operator, this contribution only considers the maintenance operations on the network as in [12]. Additionally, the ongoing energy transition is leading to new grid constraints, causing previous maintenance plannings not to be ne- cessarily feasible in near future. More recent papers studying the unit commitment problem add the uncertainty coming from renewables. In order to take these stochastic aspects into account, most of them choose to model the problem with chance constraints [13,14], multi-stage optimisation [15] or robust formulations [16]. However, very few papers consider the impact of the energy tran- sition on maintenance outage planning. An example of such a study can be found in [17]. Moreover, in all the references cited above the grid operation is assumed to be known and the uncertainty, if included, comes from the renewable generation. This paper’s main contribution is to describe a new methodology able to account for uncertainty in grid operation. By applying this methodology to future grid fow scenarios, RTE will be able to con- solidate the long-term tractability of its current maintenance practices and network design strategies. This paper provides technical insights on the problem im- plementation but the intention is to expose clearly the whole metho- dology. In particular, strong assumptions that are needed to make the whole process tractable will be discussed at length in a dedicated sec- tion. The mentioned methodology is actually a three-step approach of the problem. First, fnancial risk values are computed for diferent scenarios https://doi.org/10.1016/j.epsr.2020.106682 Received 26 September 2019; Received in revised form 27 May 2020; Accepted 1 August 2020 ⁎ Corresponding author. E-mail addresses: pascal.tournebise@rte-france.com (P. Tournebise), manuel.ruiz@rte-france.com (M. Ruiz), patrick.panciatici@rte-france.com (P. Panciatici). Electric Power Systems Research 190 (2021) 106682 Available online 28 August 2020 0378-7796/ © 2020 Published by Elsevier B.V. T