UMBRELLA is developing an innovative toolbox to support the decentralised grid security approach of TSOs, giving the opportunity to increase cooperation when facing the increased complexity in system's operation. A decentralised network security analysis with everyone "on board" looking at the same results and evaluating solutions in a coordinated and optimised way, increases the efficiency of the network operation. Furthermore, umbrella methodologies gives a step forward in the evaluation of uncertainties and their impact in different operational timeframes, the introduction of risk-based assessment and optimisation of remedial actions. This toolbox to be used in different operational timeframes includes:
- Modelling and simulation of uncertainties due to market activities, renewable energy sources on different time scales (RES forecast) and outages
- Optimisation algorithms of remedial actions in reaction to simulated risks on different time scales according to total costs and transmission capacities
- Development of risk based assessment concepts for anticipated system states with and without corrective actions
To perform the presented work, Umbrella has the following project structure:
Scientific Work Packages
Work Package 2 of the UMBRELLA project aims at developing a set of methods describing the key developments influencing the future state of the European electricity grid. Securing the stable operation of the electricity grid requires not only the consideration of the most likely (or expected) development but also of possible deviations from this scheduled path. These deviations are referred to as uncertainties. Most relevant for a secure grid operation are four sources of uncertainties, namely:
- renewable energy infeed: wind and solar power,
- power plant outages and
- short-term trading activities.
Most of the mentioned processes are more or less easy to predict individually. However, TSOs have limited information on the detail of these processes, but can only observe an aggregation of them. This makes the collection of data and its use more difficult. In order to predict the possible deviations as good as possible, these processes have to be separated from each other and in a later step aggregated again. These predictions will later be used by other work packages of the UMBRELLA project.
Work Package 3 will focus on the significant changes in energy generation. Especially the growing utilization of renewable energy sources and the nuclear phase-out in several EU countries lead to a rising number and frequency of congestions in the transmission grid. At the same time, the selection of measures to relieve these congestions is getting more complex due to the increasing number of load flow control devices like Phase-shifting Transformer (PST) and HVDC connections and their interdependencies with topological modifications and required redispatch measures. Therefore the objective of this work package is the development of an expert system that is capable of assisting the transmission system operators in the congestion management process.
The topic of Work Package 4 is risk-based security assessment, which encompasses both the probability and the severity of events. A risk-based measure carries more information than the deterministic criterion and allows for a quantitative definition of how secure the system is, as opposed to the binary N-1 criterion which only deems the system secure or insecure. A risk-based criterion allows for a more explicit definition of the trade-off between security and cost, and can lead to a more effective utilization of existing transmission capacity.
Due to the more comprehensive treatment of probabilities, risk-based methods are better suited for incorporation not only of outage probabilities but also of different kinds of forecast uncertainty. Special attention is paid to the influence of fluctuating generation resources on power system operation. Further, the developed methods include concepts that assess how cascading events, state-of-the-art technological measures (e.g. FACTS and PSTs) and how different market designs/cooperation rules between TSOs influence the overall system risk.
Prototyping Work Packages
The main objective of Work Package 5 is the provision of a toolbox which supports TSOs with the handling of the tasks and challenges arising from the growing share of electricity generation from intermittent renewable energy sources. Two different parts of a TSO’s field of work are concerned, the operational planning as well as the real-time operation process. The first step to achieve the main objective is the identification of methods most appropriate and promising for these two processes. The respective methods are provided by the research activities carried out in the framework of the work packages 2, 3 and 4 and have to be evaluated based on the demands expressed by TSOs. Afterwards, the major challenge of this work package is the synthesis of the different methods and concepts into one integrated toolbox which can be operated by a TSO as a part of the operational planning and real-time operation processes.
In Work Package 6 the functionality of the developed toolbox is demonstrated using appropriate test cases. First of all, the tests need to be specified by the participating TSOs. The required testbeds have to be made available to all functions developed subsequently in order to run the tests. The test cases have to represent a sound basis for additional analyses such as sensitivity analysis and scenario assessment. Due to the fact that the participating TSOs are significantly afflicted by the increasing share of infeed from renewable energy sources, special attention will be focused on cases with a high infeed of renewables resulting in stressed grid situations that require remedial actions. Beyond the evaluation of the toolbox, the test results will particularly be used to identify needs for further harmonisation of operational requirements in TSO cooperation rules.
Testing the toolbox is an important part of project since the toolbox has to be used in real-time. Currently the focus of the project is given to the scientific work packages. However, the next phase of the project will integrate the results of the scientific work packages into a toolbox. This toolbox will be tested and demonstrated with the help of the TSOs.
More information and results can be found on the UMBRELLA website: www.e-umbrella.eu