In Wallonia, as in other places in Europe, the political will to increase the capacity of renewable generation, the evolution of the consumption pattern (electrical vehicles, heat pumps, etc.), and the changes in the electricity markets sector will raise several challenges in distribution systems in a near future. Without re-thinking the system, issues such as congestion, under and over voltage, and renewable power curtailment are likely to appear more often than today. In addition to investing in costly physical devices, one of the key aspects is to accommodate the variability of the renewable energy sources by some demand flexibility or by some storage, which are either currently almost inexistent or under-exploited. The GREDOR project addresses these challenges.
GREDOR is composed of 5 main work packages:
- Interaction models: definition of scenarios of evolution of renewable integration and load, definition of interaction models, qualitative and quantitative analysis of these models. This package is central to the GREDOR project since it aims at defining the relationships between the actors of an electrical distribution system – and how they should interact technically and financially to achieve the societal objectives, fostering demand and decentralized generation flexibility on one hand and ensuring compatibility with scenarios to be considered for the evolution of the electrical system from now until 2050, on the other hand. This task is led by ORES scrl, one of the Walloon DSO’s. The other participants are the Universities of Liège and Mons, the DSO Tecteo RESA, the TSO Elia, Tractebel, and EDF-Luminus.
- Investment strategy: how to plan investment in the distribution system knowing that new generation will be integrated to meet targets, that some flexibility may be available and be exploited on the generation and demand sides, etc. (how? See work packages 3 and 4). Long-term planning of distribution systems will be significantly impacted by the increased development of decentralized renewable generation and possible new electricity uses. The classical fit-and-forget investment approach may prove not to be the economic optimum as compared to new planning strategies considering new control and flexibility sources (demand-side management, automatic network control, etc.). In this task, several smart tools are developed for long-term distribution system planning. The tools will derive new optimal planning strategies and help the planner to select the optimal investment strategy. The link with the control approach developed for the operational planning will be considered: when searching for the optimal future network, the optimal operation planning is taken into account. The tools can for instance decide to invest in communication infrastructure and flexibility contracts, instead of investing in cables. Scenarios defined in the interaction model work package will be used as input. This task is led by Tractebel Engineering, which is responsible for the development of the distribution planning tools, with the contribution of ULg to provide its expertise in optimization problems under uncertainty, UMons for statistical modeling and Elia for its TSO experience in transmission planning.
- Operational planning: Planning the operation of a distribution network one day or a few days ahead is a bit like driving in the fog. It is mandatory to anticipate if one wants to hedge against uncertain events in the network to avoid endangering the system, at the lowest cost. In the context of a distribution network, planning means deciding in advance when and how to use the flexibility and storage means, so that it is always possible to balance consumption and generation. Furthermore, operational planning must be coordinated with real-time control. This task is lead by University of Liège (SYSTMOD Research Unit), which has a long experience in power system optimization, and will develop dedicated decision-making software. The other partners involved are the University of Mons for building statistical models of the main uncertain variables such as wind generation, and Elia and Tractebel for their guidance.
- Real-time control: This work package deals with the real-time operation of distribution systems hosting a significant amount of renewable and distributed energy sources. Real-time monitoring and control is the last resort to protect the system against unscheduled events. This involves: (1) estimating the current operating conditions from the available real-time measurements, complemented by pseudo-measurements. This, in turn, will lead to identifying the optimal reinforcement of the measurement configuration (2) anticipating the near-future (short-term) evolution of the system, with due attention paid to variable renewable energy input (3) controlling distributed generation units, flexible loads, load tap changers, energy storage, or shunt capacitors in a smooth and coordinated manner in order to automatically correct (thermal) congestions and voltages outside limits. This task is led by University of Liège (SYSTMOD Research Unit), which has a long background in developing tools for dynamic simulation, monitoring and operation of power systems. The other partners are the University of Mons, which will build on its experience in processing statistical information to determine appropriate pseudo-measurements and short-term renewable energy forecast, and Tractebel that will bring its well-established expertise in industrial projects.
- Data collection: A sufficiently rich set of test systems is needed to assess the developments of the other work packages. As a DSO, Tecteo RESA, relying on its MV network knowledge, will collect technical data regarding distribution network material as well as provide the detailed layout of MV network structure. Besides information related to MV energy flows will be gathered and processed by statistic analysis performed by UMons. Finally, Tecteo RESA, with the help of ORES, will point out consistent test networks in order to assess the tools developed in the other tasks. For this task, Tecteo RESA will be supported by the following partners: ORES, Tractebel, EDF-Luminus, Elia, ULg and UMons.
GREDOR is funded by the Public Service of Wallonia, Department of Energy and Sustainable Building, coordinated by the University of Liège (ULg) and encompasses academic partners and partners from the power systems industry. GREDOR started on January 1, 2013.
More information at https://gredor.be/