Those familiar with industrial instrumentation will find much within the electric power industry remarkably familiar in concept. In industrial instrumentation we apply principles of physics, electricity, and chemistry to the measurement and automation of a wide range of “processes”. In the electric power industry the main “process” is the flow of electrical energy across long distances, but within that main process are a multitude of smaller processes with their own sensors, final control elements, and computation/control devices.
Within each of those smaller processes in a large electrical power system there exist automatic monitoring and control systems very similar to industrial process controls. A general block diagram showing the essential components of a feedback control system (used elsewhere in this book) applies to electrical power system automation as well:
Measurement devices in an electrical power system usually take the form of instrument transformers designed to represent high voltage and high current quantities as smaller, proportionate electrical signals. Controllers take the form of protective relays and other control systems designed to display and record the measured quantities, as well as take automatic control action. Final control is generally realized in the form of circuit breakers designed to redirect power flow and/or isolate sections of the power system.
Modern electrical power automation systems, like industrial automation, also employ sophisticated digital communication subsystems to exchange critical data such as power flow and fault diagnosis across wide regions.