Electric grids - Foreword

The power grid can be defined as the infrastructure that connects electricity production and end-use. By providing this interface, the grid ensures not only a physical link for the circulation of energy flows, but also the provision of services for the community it serves:

• it allows you to take full advantage of the proliferation of uses;

• economies of scale and optimized production tools;

• it enhances power supply reliability through redundancy and resource pooling.

By matching supply and demand, it necessarily plays a major role in achieving and monitoring equilibrium, being the key structure of "electrical systems", i.e. interconnected production – transmission/distribution – consumption. These are immense distributed machines, sometimes covering areas on the scale of continents. They are governed by physical laws that make them complex and delicate to manage, since their smooth operation depends on constant balances that can never be taken for granted, and on compliance with countless technical constraints that evolve over time.

The very general concept of the power grid in fact conceals several segments:

• the network is both a system and a set of physical elements. It is in fact made up of multiple electrotechnical devices (lines, cables, transformers, switchgear, monitoring and control) associated in a coordinated manner, and it is this association that constitutes the network. It must also be analyzed in terms of its system function, which consists of intelligently matching production with precise technical characteristics (electrical and mechanical performance, controllability or "fatal" character, etc.), a given location and uses which themselves have their own characteristics (performance, period of use, power quality requirements);

• another view is that of the major purposes of the network: the main transmission network, built today on a European scale; the distribution network, irrigating the regions; the distribution networks, constituting the local energy loop; and the domestic network, serving the various applications within a single private facility. Each of these types of network has its own purpose, economic logic and players;

• This leads to a segmentation between the public network, operated by network operators as a "natural", regulated geographical monopoly, and the private network, belonging to customers and operated under their responsibility, to link the point of delivery and end uses, a point of delivery that visualizes the boundary between public and private networks.

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