Elia Innovation

The shift towards risk assesment in the operation of the Belgian power system, the projects GRASP & GARPUR

Historically in Europe, power system reliability management has been predominantly relying on the “N-1” criterion – whereby the system should be able to withstand at all times an unexpected failure or outage of a system component (power plant, transmission line or transformers).

Today, the increasing uncertainty of generation due to intermittent energy sources, and the growing complexity of the pan-European power system, increases the need for new reliability criteria – with a better balance between reliability and costs.

Elia is working on the development of new methods to plan and operate the Belgian power system within the Phd project GRASP and European  project GARPUR.

For more info, visit http://www.garpur-project.eu/

What are these projects about?

Elia’s top priority is to guarantee the reliability of the power supply. New approaches are required to evaluate grid reliability while taking account of the intrinsic variability and inherent uncertainty of RES generation. However, these approaches should also fit to the requirements of operating the power system 24/7: they should be fast, understandable by the operators and robust.

The projects Garpur and Grasp aims at on the one hand developing these new methods but also to test them in close to real life conditions to :

  • Identify needs for data collection and sharing required by these new methods
  • To show the value of migrating to probabilistic practices
  • Create trust in these new methods and set the base for the development of industrial grade tools and softwares.

What the use for Elia and what will be the outcome for society?

New probabilistic reliability approaches could provide multiple benefits, such as a more efficient grid use, an increased reliance on wind or solar or more transmission capacity given to the market. Yet, probabilistic methods are still perceived as complex and time consuming. In addition, there may not be sufficient and reliable statistical or other data available for evaluation, and finally practical experience to point to.

These barriers must be overcome by demonstrating the benefits of such new approaches to support TSOs in their daily operation activities. GARPUR and GRASP are two of the many initiatives performed by Elia to ensure this objective. This way, Elia will be able to continue ensuring the reliability of the power supply at an affordable cost for society.

Elia is currently working on the development of new methods for different planning and operational aspects of the Belgian power system:

GRASP, a PhD project, aims to develop a methodology for evaluating grid reliability at the operational planning stages that factors in forecasting errors regarding wind and PV generation.

The EU project GARPUR aims to develop new probabilistic criteria and relevant indicators for assessing reliability at different stages (system development, asset management and system operation) and evaluating their practical use (with respect to the current N-1 criterion).

While both projects focus on the same challenges, they approach them from different angles and have different objectives:

  •  GRASP is starting out from current practices and propose new procedures, aiming to produce recommendations based on a prototype that can be directly tested based on real situations in Belgium[r1].
  •  Garpur is fully reviewing the approach from the grid development stage (decided years in advance) to real-time operation and aims to produce EU recommendations on how to shift gradually towards a probabilistic approach.

The two projects will end in Q4 2017. Elia is already working on how to transfer and implement the results and recommendations of these demonstrations into its operational practices.


The power system operational situations are much more diverse and frequently evolving compared to the past. Deterministic criteria such as the well-known "N-1 criterion" should progressively evolve towards so called “probabilistic” reliability criteria. They would allow us to ensure system reliability at the cheapest cost for the society in a world in transition to its decarbonisation”

Jonathan Sprooten, Head of power system planning

“GARPUR and GRASP allowed us to demonstrate the value of moving progressively towards a probabilistic approach to reliability management. In particular, the work we performed in GARPUR and tested in a close to real life situation showed how we could improve the analysis of our long term studies (2030). We should work now with our colleagues from Asset Management and from the National Control Center to move from the “demonstration” to the development of an industrial grade tool we could use in our daily operations”

Arnaud Vergnol, Power system Planner