In everyday life, unplanned events are often a positive surprise. An unexpected sunny day, a banknote in an old jacket or a last-minute visit from friends. But when it comes to the grid, anything unplanned is undesirable – and can even be dangerous. The grid capacity of the Swiss transmission grid is precisely calculated to the nearest quarter of an hour. If unplanned electricity suddenly flows through our grid, i.e. electricity that was not foreseen in the calculations, this can cause overloads of grid elements. In this type of situation, Swissgrid must intervene and rebalance the grid. Consequently, unplanned flows are always associated with effort and risks in the grid.
For several years now, Swissgrid has been working with the electricity industry to warn people of the risks that unplanned flows pose to our grid stability.
What are unplanned flows?
For several years now, Swissgrid has been working with the electricity industry to warn people of the risks that unplanned flows pose to our grid stability and therefore to Switzerland’s security of supply.
When electricity flows, it is impossible to predict which path the current will choose. This is because electricity always seeks the path of least resistance. This means that if electricity has to flow from point A to point B, it will not necessarily flow there directly. In the event of cross-border energy exchange, it is possible that only part of the electricity exchanged will flow directly across the national border. Another part might flow through the grid of a neighbouring country. There is a difference between the volume of electricity exchanged and the physical flow between the two countries or parties trading the electricity. The difference between the trade flow and the physical flow is the unplanned flow – the part that flows through the country that wasn’t actually involved in the electricity exchange. There are two types of unplanned flows: transit flows and ring flows.
The difference between the trade flow and the physical flow is the unplanned flow – the part that flows through the country that wasn’t actually involved in the electricity exchange.
Electricity likes to travel...
We talk about transit flows when electricity is exchanged across borders but makes its way through a third country. To understand this situation, it can be compared to a journey: a school class has to travel from Offenburg (Germany) to Strasbourg (France). As the direct train is full, the students split up. The children who can’t get a seat on the direct train catch another train that goes via Basel. The whole class starts at the same point and meets at the same place – but they have travelled via different routes. The same thing happens with transit flows. When an exchange transaction takes place, electricity produced at a power plant may be intended for consumption at another location. However, not all of the current will flow to the destination via the same path. Part of it will find its way via another country. This country is not involved in the exchange.
...or it goes round in circles
A ring flow is when a country exchanges electricity within its own borders. However, the electricity flows along the line of a neighbouring country. The electricity is therefore exchanged in country A, but flows from country A to country B and back again. If we compare this with a train journey, it is like travelling from Ticino to Valais. Passengers have to change trains in Italy and travel from there to Valais. This is the fastest connection – the path of least resistance.
Swissgrid is doing everything it can to minimise unplanned flows. An electricity agreement between Switzerland and the EU would be a long-term solution.
The lack of an agreement leads to nasty surprises
But why are there more and more unplanned flows in the grid? One reason for this is the lack of an electricity agreement between Switzerland and the EU. Yet an agreement of this kind is essential for Switzerland’s security of supply. With 41 cross-border lines, the Swiss electricity grid is highly integrated into the continental European grid. Interaction with European transmission system operators is one of Swissgrid’s daily tasks. However, due to the lack of an electricity agreement, Switzerland is increasingly being excluded from important platforms. Furthermore, it is not adequately included in grid capacity calculations. As a result, Swissgrid is unable to predict the precise load on the grid, and Swissgrid operators have to use electricity to stabilise the grid. This is associated with effort and costs, and questions are increasingly being raised about the availability of these «remedial actions», given that they usually utilise hydropower in Switzerland.
The 70% rule is another challenge. Three years ago, the Minimum Remaining Available Margin law came into force for EU countries. This stipulates that all EU transmission system operators must reserve at least 70% of their transfer capacity for cross-border exchange. However, only EU countries are included in this cross-border exchange. In the absence of an agreement with the EU, Switzerland is not taken into account.
Looking to the future
Unplanned flows are undesirable in the grid, and are always associated with risks and effort. Unplanned flows will increasingly lead to overloads of grid elements. In this type of situation, Swissgrid must intervene and rectify the problem. This leads to a greater threat to grid stability, and therefore to Switzerland’s security of supply, as well as ultimately resulting in higher costs for Swiss electricity consumers. Swissgrid is doing everything it can to minimise unplanned flows. An electricity agreement between Switzerland and the EU would be a long-term solution.