A bulk-power system is the large-scale electric grid that generates, transmits, and routes electricity across wide areas. It includes power plants, high-voltage transmission lines, substations, control centers, transformers, and related equipment needed to keep electricity reliable and balanced in real time.
It matters in cyber security because disruption at this level can affect millions of customers and other critical services at once. Attackers may target control devices, remote access paths, firmware, vendor maintenance channels, or supply-chain weaknesses to manipulate operations or cause outages. Defenders focus on asset inventories, network segmentation, strict authentication, signed updates, monitoring, and recovery planning. In practice, bulk-power system security is about protecting both the physical grid and the digital systems that operate it.