Critical infrastructure systems include critical physical processes. These processes are controlled by automation systems which combine humans, computers, communications and procedures. Automation systems are used to increase the efficiency of process control by trading of high personnel costs for low computer system costs. They also contribute to improved performance by taking advantage of faster computer control instead of human reaction times. The automation systems are often referred to as process control systems (PCS) or Supervisory Control and Data Acquisition (SCADA) systems, and the widespread use of such systems makes them critical to the safe, reliable, and efficient operation of many physical processes.
Power system operation is becoming ever more complex in today’s deregulated environment. Maintaining reliable service depends on increasingly sophisticated control and protection algorithm and also the automation equipment. At the same time, system and device limits are being tested. Interconnected dependent systems give rise to new classes of relationships, both physical and economical. Increased deployment of protection schemes designed to allow increased loading of devices and operation closer to transient and static system limits heightens the possibility of unstable modes resulting from typical stimuli. Complex control at the EMS (Energy Management Systems) level worsens these issues.
The term SCADA (Supervisory Control and Data Acquisition) is used to represent the communications component and control architecture that provides control capabilities to a power system. Most often included are elements in a power system responsible for system monitoring and control communications. The term SCADA includes all automation elements for the electrical infrastructure: EMS, protective relaying, AGC (Automatic Generation Control), WAP (Wide Area Protection), communications, etc. the elements that make up a SCADA system provide the sensory and command interfaces between the bulk power system and its associated control functions.