On the critical situation in the Swiss transmission grid on Monday, 20 May 2019, when individual grid elements were considerably overloaded or threatened to be overloaded, TSCNET shareholder Swissgrid, the Swiss transmission grid operator (TSO), has already completed an initial analysis. On that day, with a high Swiss domestic electricity production of around 12 GW, a total of around 4.5 GW was exported, most of it to Germany. Since the load flows typically run in the opposite direction, this atypical situation led to security breaches in the grid.
For reasons unknown, the European grid forecasts did not anticipate that export volumes would increase in the short term from Sunday to Monday. Swissgrid had thus to resolve the grid security breaches in real-time operation in cooperation with colleagues from the European TSOs. This incident shows that the forecasts can deviate considerably from the actual load flows. It also indicates the crucial importance of integrating all transmission grids in Europe, including Switzerland, into the grid modelling, so that any threats to grid security can be identified in advance and coordinated measures can be taken.
However, since Switzerland is excluded from market coupling due to the lack of an electricity agreement with the EU, the deviations between forecasts and effective load flows are likely to increase. An agreement, on the other hand, would include Swissgrid in the models for load flow calculation and capacity allocation of the European partners and provide the TSO with better information on the load flows through Switzerland.