What is the smart grid and what will its role be in the future power grid?

The smart grid is a set of technologies, mainly computer-based, that allow the management of the power grid to be optimised, making it more secure, more efficient, more flexible and more economical. The smart grid will play a crucial role in enabling the grid to manage the growing and fluctuating share of intermittent electricity from renewable sources (wind and solar).

Today, the electricity grid works as follows: electricity, produced in large power plants (nuclear, hydro), is fed into the high-voltage grid and then transported to the end user via increasingly branched medium- and low-voltage grids. The least flexible power plants, such as nuclear power plants, continuously produce a constant volume of electricity (so-called “ribbon” electricity). The more flexible storage hydropower plants open and close their gates according to demand, so that the amount of electricity injected into the grid at any given time is equal to the electricity consumed by users. If this delicate balance is upset, the grid “falls”, resulting in a power outage that can quickly spread throughout the entire system.

With the ongoing energy transition, a paradigm shift is taking place. This transformation of the power grid will require the use of so-called smart grid technologies. The increasing decentralisation of generation, and the fluctuating injection of green electricity from solar and wind energy into low-voltage grids, will make balancing generation and consumption much more complex [→ Q48]. The flexibility of storage hydroelectric plants will no longer be sufficient to balance the grid. It is therefore necessary to introduce four new elements:

• The ability of the grid to transmit electricity in a bidirectional manner, and in particular to “uplift” the electricity ultimately injected by many small generators to medium and high voltage levels [→ Q98].
• Storage capacity at the local (at the generator), regional and national levels for surplus electricity [→ Q74].
• An ability to make production more flexible, by modulating in real time the electricity production of small structures (e.g. cogeneration units, incineration plants, small run-of-river hydroelectric plants, etc.) that have been aggregated into “virtual power plants”. These can be controlled dynamically from a remote location by the managers of these plants or the network, rather than in an inflexible manner by the operators of these different units.
• A capacity to make demand more flexible, making it possible to influence in real time the level of consumption of certain users in order to match production fluctuations as closely as possible. This is the notion of “Demand Side Management” (DSM) [→ Q78].

With all these new features, the electricity network will become extremely complex to manage: a Swiss network with 250,000 km of lines, 4 million connected users, and soon hundreds of thousands of decentralised production facilities (mainly photovoltaic). Advanced information technologies will be indispensable for collecting, transferring and managing millions of items of data on the state of the grid in real time. This mass of information will be processed centrally or decentrally by complex algorithms, which will optimise management decisions and ensure a balance between electricity production, storage and consumption while guaranteeing a high level of network security and efficiency. All of these technologies are covered by the generic term “smart grid”.