Load shedding to secure power grids is a proven way to prevent network crashes in Europe.
"Bulk consumers in particular, such as cement mills or large cold stores, have special contracts as load shedding customers. They must automatically shut down within defined times, typically in the seconds range. Even in the electronically networked (intelligent) power grid, all end users can be equipped with load shedding control. Load managers can selectively switch off end devices at short notice; suitable are consumer devices such as boilers, refrigerators and freezers, if they are equipped to be controlled." (Translated from the German version in Wikipedia)
In the Fair Grid network, the Fair Box controller autonomously controls disconnecting and connecting large consumers such as air conditioners at an under-frequency range between 49 and 48 Hz. The circuits are linear and event-based in order to achieve a fair distribution between the different power consumers and a rocking and deceleration avoid frequent switching on and off. Criteria for prioritized switching on and off may be waiting times, energy consumption, peak power, solar power, weekdays, random circuits or pre-orders.
Web links: https://de.wikipedia.org/wiki/Unterfrequenz https://physics.stackexchange.com/questions/2641/how-does-load-affect-frequency-on-the-power-grid
The Fair Box has a potential-free ON / OFF auxiliary contact for switching large loads. A radio output with equivalent function is available as an alternative to facilitate the installation. If large loads are not switched off in short term the event of imminent grid overload the assigned phase is switched off by the main switch of the Fair Box as well as in the event of a repeated sabotage message to the grid operator.
For any power grid, power-up after grid outage such as a maintenance or repair is a particular challenge since motorized consumers particularly need significantly higher currents during restart. The Fair Box automatically switches after a power failure with a time delay and thus facilitates the so-called black start after power failures. It is a fair save system.
Businesses, authorities or hospitals may agree by contract a higher protected base load with the network operators, to the extent that the cost of providing a higher electricity generation capacity is billed commensurately from the originator. By prior notification to the network operator at the latest one week before the event, the cut-off and cut-off frequencies can be improved in favour of the customer. However, this results in a worse position during the week before the event.