An integrated approach to substation automation problem based on multifunctional protective relays

In recent years the utility business has faced changes related to privatization, deregulation and internationalization. The diversification and complexity of functions required by most distribution utilities becomes a strong trend of evolution. At the same time the integration of an increasing number of functions in digital devices provides resources for new and more complex schemes. Thus advanced automation algorithms can be implemented associating extra processing power with powerful communication networks. Modern software packages conceived to interface protective relays also play an important role in the global solution. This paper proposes a highly integrated approach for control and automation in distribution substations, based on the modern EFACEC protective relays and its SCADA system. The integration in these units of control functions such as automatic reclosing, automatic voltage regulation, load shedding and restoration, circuit breaker failure protection and other control and supervision functions is analyzed. The improvement of classical algorithms and the definition of new methods for automation based on the interaction among different units through the local area network are described. The conclusions are based on an economical and technical analysis, where potential advantages and benefits combined with new possibilities are evaluated.