The start grid represents the starting point for the grid planning process. This European grid model includes all grid elements that are in operation today and that will still be in operation or will be put into operation by 2030.
The reference grid is formed with the help of market and grid simulations, as well as stress tests. This is done by adding new Swiss grid projects to the start grid until there is no longer any relevant grid congestion in the various scenarios. The grid expansion requirements identified in this way are coordinated with the DSOs connected to the transmission system and foreign transmission system operators so that coordinated planning of the entire grid can take place.
- The result obtained from the market simulation shows the hourly power plant deployment per bidding zone (a country can consist of one or more bidding zones) and the resulting cross-border electricity exchange. The target function is to cover the load in each bidding zone, at minimum generation cost, taking into account the maximum cross-border capacity between bidding zones. The results per bidding zone from the market simulation are allocated to the nodes of the European grid model by means of mapping. This means that the hourly generation and the consumption per grid node are taken as input values for the grid simulation.
- For each scenario, grid simulations are calculated with the European grid model, and any congestion (n-1/tension violations) is detected. The utilisation of the grid elements per scenario is created from this, at which point it becomes clear where there is still a need for grid expansion. The NOVA principle is always applied when upgrading the grid. The NOVA principle stands for grid optimisation before grid enhancement before grid expansion. It aims to minimise the impact of grid expansion on the environment and the landscape.
- The start grid, supplemented by additional grid projects, is now subjected to various stress tests (e.g. multiple failures, short circuits, frequency/voltage variations, etc.). If the stress tests reveal a need for further grid upgrades, then additional grid projects are added in this step to make the grid sufficiently robust to cope with the conceivable extreme situations.
After the finalisation of the reference grid, the target grid is formed. All additional grid projects in the reference grid are evaluated with the help of the cost-benefit analysis. The evaluation of each individual grid expansion measure is carried out from an economic as well as an environmental and technical perspective and serves as a proof of need. In principle, only those projects where the benefits prevail will become part of the target grid.
The totality of the additional grid projects in the target grid compared to the start grid forms the Strategic Grid.
Strategic Grid 2025
Swissgrid had already developed a multi-year plan for the needs-based modernisation of the transmission system back in 2015, before the entry into force of the statutory provisions on the grid development process: the «Strategic Grid 2025». The «Strategic Grid 2025» includes ten projects. The defined projects are all in various stages of implementation. The following diagram provides an overview.
Swissgrid has already been able to complete some of the projects from the «Strategic Grid 2025», while others are in the project planning or implementation phase. Swissgrid thus makes an important contribution to the security of supply in Switzerland.
Experience shows that lengthy approval procedures in particular, as well as time delays due to objections or legal proceedings, mean that the project planning phase can take a very long time.
The needs-based expansion of the grid is crucial for Switzerland’s long-term security of supply. It is therefore important that political bodies, the authorities and the public support this critical infrastructure and that the modernisation of the transmission system is accelerated by means of efficient approval procedures.