30.09.2022 | Grids: why the voltage conversion from 50 to 110 kV is crucial

No electricity supply security without a powerful grid

A powerful and stable grid is crucial for ensuring electricity supply security. Getting it right takes years of forward planning. Ivo Müller (Head of Operation & Maintenance) and Jörg Kottmann (Head of Asset Management) explain how Axpo is making its grid fit for the future.

Ivo, the prospect of an electricity shortage in winter has been making headlines. What role does the grid play in this? 

It is important to look at the overall system. After all, it is not possible to have electricity supply security without a stable grid. To ensure that the grid is stable – i.e. that there are no outages – the amount of energy fed into it must be exactly equal to the amount that is being consumed. The grid must then also have enough capacity to transport the required electricity reliably at all times. 

And where does the biggest challenge lie – on the energy side, or the grid side?

IVO: An electricity shortage is actually a problem on the energy side, not on the grid side. It means that electricity demand cannot be fully covered by the available production capacities and imports over a longer period of time. The risk of an electricity shortage has risen significantly this year.

What does this mean for Axpo as a grid operator at supply level?

IVO: The Federal Council has agreed various management measures (prohibitions, rationing, cyclical grid disconnections), which it will enact in the form of a regulation in the case of extreme emergency. Like all other grid operators, Axpo is part of OSTRAL (the Organisation for Power Supply in Extraordinary Situations), which has been tasked with implementing the measures. Axpo has therefore made preparations to implement them as smoothly as possible. For example, we have developed grid disconnection plans, so that we can divide our medium-voltage grids into small sub-grids and switch off the individual sub-grids in accordance with the Electricity Management Ordinance (BVO). Of course, we will only put these plans into action after the Federal Council has enacted the BVO.

What are the main reasons behind the high demand for electricity?

JOERG: More and more oil and gas heating systems are being replaced with heat pumps, which is fuelling the demand for electricity. We are seeing a similar effect in the area of electric vehicles. Due to the substitution effect alone, the consumption of electrical energy will increase disproportionately in relation to overall energy consumption. The number of newly registered electric cars is increasing rapidly. At the same time, demand is being driven by the digitalisation of society. For example, the additional data centre facilities that have been or will be installed in Axpo’s supply area are already making themselves felt. Their peak loads alone make up more than 10 percent of the total load. All these factors are putting ever more pressure on the grids each year.

IVO: The decentralisation of electricity production – especially the planned expansion of photovoltaic systems – is posing a further challenge for the grid. The system will shift increasingly from centralised, predictable electricity generation to decentralised, volatile generation. This will not be possible without a powerful and efficient grid. Having such a grid is crucial to ensuring a bright energy future.

And do we have such a grid?

JOERG: Axpo already started to gradually expand its entire transregional distribution grid from 50 to 110 kilovolts in the mid-1980s, when the company was still operating under the name NOK. Even back then, electricity consumption was rising dramatically. Thanks to the far-sighted planning of those in charge at the time, we are in a good position today. The large-scale voltage conversion project will take around five years to complete. We are convinced that it will enable us to meet the requirements of the energy transition. It will, of course, be followed by investments to improve and modernise the grid.

Where are the potential stumbling blocks to completing the voltage conversion successfully?

JOERG: The lengthy approval processes pose a major challenge. By law, power lines have to be laid in the ground if the additional costs are not twice as high as for an overhead line. When submitting plans to the Swiss Federal Inspectorate for Heavy Current Installations (ESTI), the different options have to be presented. Despite this requirement, which is intended to encourage underground cabling, the process does not appear to be getting any quicker. In addition, there are numerous other legal requirements and objections that can delay a project by years.

But how exactly does a voltage conversion contribute towards the security of supply?

JOERG: Instead of building further conventional and bigger grids, we are adapting the existing distribution grids so that more electricity can be transported through them. With the voltage conversion from 50 to 110 kV, we are doubling the output that can be carried in the network. At the same time, we are reducing grid losses by 75 percent. The voltage conversion makes sense from both an environmental and an economic perspective. It also ensures that the grid will be powerful, stable and efficient in the future as well.

Axpo ‘drives’ on main roads

With its transregional distribution grids, Axpo’s grid infrastructure covers high voltages in particular. If we were to compare the electricity grid with our road network, these would be the main roads. Through its own distribution grids, Axpo is connected on one end to the transmission grid of the national grid company Swissgrid, and on the other end to the distribution grids of customers, i.e. the cantonal and regional power stations. Swissgrid is responsible for the 380 kV and 220 kV grid. These could be compared to motorways. The cantonal and regional power stations are responsible for fine distribution. They transport the electricity to our plug sockets. Their grid could be compared to regional and district roads.

Regulatory basis for grid planning is in place

The Federal Council wants to bring electricity grid planning into harmony with future developments in the energy sector. It is doing so on the basis of the 2030/2040 scenario framework for the energy industry, which will be reviewed and updated every four years. The grid operators, including Axpo, can decide themselves how to apply the national requirements from the scenario framework to their grid territories and nodes. They also bear the cost of converting and expanding the electricity grids in Switzerland. The requirements are taken into account in the periodic multi-year planning that is subsequently carried out by the grid operators. The Federal Council is expected to approve the scenario framework in the fourth quarter of 2022. This will give the grid operators a strong basis on which to carry out or update their grid planning. 

More articles for you

Show all

Energy market

Weather and politics strong drivers of energy markets

European Energy Markets Monthly, July 2024

Read more


Hydrone propels pilot expertise sky-high

Aerial efficiency: monitoring power plants and the grid using drones

Read more


Pigniu reservoir: the first-ever removal of deposited sediments via flushing

The Pigniu reservoir of Kraftwerke Ilanz AG was temporarily completely emptied

Read more

Energy regulations

Additional regulation for electricity companies with ‘systemic importance’?

In the wake of the energy crisis, the Federal Council has presented a draft for the regulation of electricity companies with ‘systemic importance.’

Read more