Centralized Protection and Control for Transmission System Operations: Practical Applications and Perspectives

Since substation automations systems were introduced in the 1990s to protect, control, and automate high-voltage and medium voltage substations, several new technologies have been applied to improve the functionality, performance, and efficiency of the design and architecture. Digital substations are beginning to replace substation automations systems, benefitting from new architectures that are based on digital interfaces provided by intelligent primary devices and related sensors. This transition was prompted by the intensive work in standardization of communication protocols and data models dedicated for power system automation, as defined in the International Electrotechnical Commission (IEC) 61850 series of standards. The evolution of technologies and performances driven by microelectronics enabled the functional integration of previously separated devices onto common hardware over the last three decades. Still, the functional integration was limited by requirements concerning reliability, resilience, testability, and life-cycle perspectives. In a substation, any device, such as a protection relay, was allocated to a bay, a feeder, or a zone. Applying concepts of IEC 61850 concerning the separation of physical signals, their conversion into digital information, and allocation of application functions using this information from any physical device, makes it possible to think about the next generation of digital substations. Based on virtualization technologies developed in the world of information technology (IT) to dramatically improve the design, operation, and maintenance of IT systems, centralized protection and control systems (CPCs) would allow an even more flexible and economic way to protect, control, and automate substations.