The role of SMS (substation monitoring systems) in enhancing protection and control functions

The basis of modern, microprocessor-based station control is an information bus, connecting all feeder units together. The SMS (substation monitoring system) is a part of the SCS (substation control system). The SMS deals mainly with the analog measuring quantities, the signals and the settings of the measuring, protection and regulation functions. Basically, all feeder-orientated tasks are performed in feeder units, where all feeder-related data are also stored. These feeder units are linked by the mentioned (serial) information bus, allowing the free exchange of information between all feeder units and the hierarchical higher levels, like substation units, network etc. The functionality is given by the software and I/O circuits only and comprises protection, measurement, regulation etc. The protection functions are autonomous. Based on this concept-called `PYRAMID´-a lot of substations have been designed and equipped