Reduction of transport loss, increase of transport capacity

Voltage conversion on Primeo Energie's medium-voltage grid in the Jura Nord grid area from 13 kV to 20 kV

Back in the early 1980s, management decided to prepare the medium-voltage grid for a future voltage conversion from 13 kV to 20 kV. Since then, Primeo Energie has only installed 20 kV-compatible components for replacement and new investments.

Transport losses will be significantly reduced as a result of the voltage conversion – from currently 6.3 GWh to 2.6 GWh. This corresponds to an annual recurring saving of 3.7 GWh (3,700,000 kWh), which in turn corresponds to the annual production of a photovoltaic system with 18,500 m2 module area. At the same time, transport capacity increases by more than 50%.

The voltage conversion reduces the cost of grid use in the medium and long-term.

The demands on the power grid are increasing. Population growth, digitalisation, decarbonisation of heating and traffic, decentralised feed-in from photovoltaics and other sources require a powerful and low-loss grid.

The conversion will take place in six regions over the next few years. Roughly speaking, this will be from the south to the north. We will start with the substation/region Liesberg in the second quarter of 2023. The project will be completed around 2029 in the region of Saint-Louis. The dates will be adjusted as needed.

Project schedule and geographic overview

Six regions – step by step

  • The grid area has been divided into six regions.
  • The actual conversion will take only a few weeks per region.
  • The regions will be connected by coupling stations until the next region has been converted.
  • Start in March 2023
  • The dates for the subsequent regions are being updated on an ongoing basis.

Questions and answers

What is it about?

If a new medium-voltage grid were to be built on a greenfield site today, the operating voltage would be 20 kV. The required components are standard materials as used throughout Switzerland and Europe. However, the power grids have grown historically and the decision on which voltage to use for which grid level was made long ago. The decision was usually based on the available insulation materials and the voltage supplied by the connection to the first "large" hydropower plant.

Thanks to the preparatory work, which has been underway since the early 1980s, Primeo Energie is now able to convert to a modern operating voltage. The benefits of lower transport losses and the higher transport capacity will have an effect for decades.

What is the medium-voltage grid?

The medium-voltage grid, also known as the regional distribution system, can be compared with the main roads in a road network. Experts refer to Grid Level 5. At this level, we increase the voltage from the current 13 kV to 20 kV.

The seven grid levels of the Swiss power grid

What are the reasons for this voltage conversion?

Increasing the voltage significantly and permanently reduces the transport losses. At the same time, transport capacity on the same infrastructure increases significantly. The demands on the power grids are increasing. Decentralised feed-in and the decarbonisation of heating and transport require a strong grid.

Primeo Energie has been consistently pursuing the goal of one day converting the voltage since the early 1980s, which now allows us to implement the advantages with only a small amount of residual investments. (As standard, 20 kV-compatible components have been available since around the mid-1960s. Previously, operating voltages of 16 kV or less were used). As a power grid is a large system consisting of many components, it takes planning and time to prepare and implement systematic changes.

What are the benefits for customers?

An efficient power grid at all grid levels is the basis for a high level of supply reliability. The voltage conversion increases the transport capacity on the medium-voltage grid by more than 50%.

The voltage conversion reduces the cost of grid use in the medium and long-term.

Is there a legal basis for this?

Electricity Supply Act (ESA), "Tasks of the Grid Operator, Art. 8"

For safe, effective and efficient grid use, the operator must determine the voltage for a particular grid level.

Why now?

Load flows are changing because of the increasing number of decentralised energy producers. In the past, customers "pulled" the energy from the power station by means of a cable. Today, energy is also "pushed," e.g. from one commune with several photovoltaic systems to another.

Decarbonisation of heating and transport leads to lower overall energy consumption (oil, petrol, gas). Heat pumps and electric vehicles are significantly more efficient, but the shift from fossil fuels to electricity puts an additional strain on the power grid.

Electricity is continuously gaining in importance. We have known this since the 1980s. Since then, Primeo Energie has installed only 20 kV-compatible components for replacement and new investments. This allows us to take the final steps and to convert the voltage.

Who is affected by the conversion?

It's similar to a road construction project. You can expect delays when driving through areas where roadworks are underway. In the case of voltage conversion, this means: The day on which the transformer substation supplying your property with electricity is converted, you can expect a power cut of one to two hours. We will inform each customer of the exact times.

Industrial customers with their own medium-voltage power grid will be particularly affected. Their systems must also be capable of 20 kV. This is another issue that we have been discussing since the early 1980s. Systems that are not yet designed for this purpose will have to be replaced in the near future.

What does this mean for you? What do you need to do?

Please note that the scheduled power cut will affect you for approximately one to two hours. We will inform you about the project and the precise time of the conversion as we go along. Please take a moment and think about what a power cut means to you. This might sometimes be unplanned. If it should not happen to you under any circumstances, you must install an emergency power supply that is independent of the grid. We will not publicly post the exact switch-off times for each property. Such information will be provided only individually.

We actively approach industrial customers with their own medium-voltage power grid systems. They can, of course, also contact us.

General recommendation: Don't plan the biggest party, most complicated experiment, record product, or similar a occasion during the time window of the conversion.