This is an abstract proposal for 2 presentations that have a dialogue in presenting, and a joint paper.

IEA TCP WIND Task 25 ”Design and Operation of Energy Systems with Large Amounts of Variable Generation” compiled Recommended Practices for power system impact studies, what has traditionally been called wind and solar integration studies. This provides research institutes, consultants, and system operators with the best available information on how to perform an integration study. It is also useful in benchmarking any integration studies: the recommendations check list can be used to mark what has and has not been taken into account. The latest update, to Edition 3, includes recommendations for very high shares of wind and solar – wind and solar dominated power systems, with energy system coupling. It is based on more than 10 years of work within the International Energy Agency Wind Technology Collaboration Programme (IEA Wind TCP) Task 25: Design and Operation of Power Systems with Large Amounts of Wind Power and the IEA Photovoltaic Power System Programme (PVPS) TCP Task 14: High Penetration of PV Systems in Electricity Grids.

The Recommended Practices contain the following sections: Input data; Scenario set up; Adequacy; Operational impacts; Dynamics; Analysing and presenting the results. Each section highlights the issues with the main recommendations, for small/medium wind and solar shares in the power system and also for wind and solar dominated systems.

Following the presentation of Recommended Practices checklist there will be a dialogue on how this has been taken into account in a case study investigating electrification of industry and transport in Sweden. Sweden benefits from a carbon-neutral electricity system composed by hydropower nuclear power and wind power. However, with a large energy-intensive industry, including iron and steel as well as petro-chemical industry, which need to move away from fossil-fuels the electricity demand is expected to double.

To analyse the changes in the electricity and energy system that electrification of the industrial and transport sectors entails, a large geographical range is required to capture trade flows and a long time horizon that reflects changed conditions for investments in new electricity production and storage with associated infrastructure over time. At the same time, a high geographical resolution is needed to represent transmission constraints in the electricity grid and a high time resolution to capture the variability of weather-dependent electricity production. To cope with this, the analysis in is based on three different electricity system models in combination; a European investment model to study the development of the electricity system based on today's capacity mix up to the year 2065 followed up by calculations with an investment model with high geographical resolution for the Nordic electricity system from which results are used to calculate flows of active and reactive power in an electricity grid simulation model and to check that the calculated electricity systems are physically and electrically reasonable in normal operation and to identify the need for reactive power compensation.

We will go through the different modelling choices made in the study, relate them to the recommended practises, discuss the implications on results and future work.