Going back to basics: electricity infrastructure

This second session on electricity touched upon the transmission, distribution and regulation.

To start the session, we illustrated it by presenting the section of a 70kV underground transmission cable used in regional transmission. Raw materials are key in the power system. The core of a transmission cable is made of conductive material that can be aluminium or copper. Copper conducts better the electricity and would have a smaller section than an aluminium conductor for the same rated power to be transmitted but the choice of material will impact the price.

The presented underground cable has an aluminium core, an insulation made of cross-linked polyethylene (XLPE) and an outer protective layer made of PVC. For an  overhead line, the look would be completely different as we would have bare conductors without insulation, the surrounding air being the insulation. Underground cables are better protected from harsh weather but more complex to install and to repair in case of failure. Overhead lines are more vulnerable to environmental factors but easier to maintain and to construct. They are also less expensive than underground cables. Once some physical elements of the power grid were explained, we moved to the different levels of the grid: transmission is accomplished via the high-voltage transmission grid. Distribution is at the local level, electricity is delivered to end-users through lower-voltage distribution networks. To ensure the proper functioning of this complex system, independent National Regulatory Authorities (NRAs) regulate in each EU member state.

Our first speakers explained the transmission side of the electricity sector to the audience. ENTSO-E, entity mandated by EU legislation, has Members from all across Europe (Members from the 36 European TSO’s, but also covering non EU members). The presentation included interconnections, the different synchronous areas where countries are functioning at the same frequency and are electrically interconnected for real time synchronization of electricity generation and consumption, TNYDP, network codes. The role of the TSO is to make sure that the grid operates safely. It is also to develop the grid and maintain security of supply and ensure the n -1 criteria which is that when one element fades in the system, the system still operates safely. We were then given concrete examples of grid extension.

While most countries have just one TSO, there are more than 2000 DSOs in Europe.

The Distribution System Operators (DSOs) operate, manage, and sometimes own the local and regional energy distribution networks, which transport electricity to end users at lower voltages than the transmission network. Our speaker presented the critical role of DSOs in the electricity system and its evolving role, as the energy system itself is evolving.We were also given technical explanations including on substations and transformers One of the French DSO explained in details how an electricity DSO functions, including key figures, grid planning and new connections possibilities.

Transmission system operators and distribution system operators are regulated entities. The 3^rd main actor of the power grid are the regulatory authorities. The Austrian regulator explained in detail the essential role of Regulatory Authority in each EU country

The informative session ended with the energy intensive industry, namely the chemical industry and paper industry, explaining the consumption part of the value chain.