Interaction of machine and line protection within a coordinated substation control system

Station control systems coordinating control and protection allow an easy interconnection of machine and line protection and provide reliable, fast, and flexible protection of the machine and the related network. Such a concept is described. It provides a unified system which coordinates substation control and protection based on microprocessors in a decentralized configuration. Numerical relays have a serial interface normally. Microprocessor-based substation control provides both global data and communication links. Therefore, the framework of a substation control system coordinating control and protection provides all facilities to solve the problem of machine protection generally. The basic considerations, the concept, and examples are presented