Networked controllers
Voltage setting - Role, obligations and organization of producers for the needs of the French electrical system

The reactive energy produced or consumed by the generators must pass through the transmission network to reach the consumer. The current associated with the circulation of this energy generates joule losses in the transmission lines and cables, as well as voltage drops. What's more, its production generates additional losses and wears out the equipment of generating units. One way of compensating for this as close as possible to distribution networks, and therefore to consumers, is to use reactive energy compensation devices connected to the network.

There are two types of voltage and reactive power control devices: static devices, such as capacitors and inductors, and dynamic devices, such as synchronous compensators and FACTS. The installation of these devices is usually the responsibility of the transmission system operators.