Power system modelling and analysis in a mixed energy management and distribution management system

Energy management systems (EMS) and distribution management systems (DMS) have developed over the years as two distinct branches of control centres working on supervisory control and data acquisition (SCADA) platforms. A hybrid EMS/DMS system requires higher level security analysis functions such as state estimation and contingency analysis for EMS and feeder voltage and loss optimisation for DMS systems. This paper highlights specialities of these hybrid systems. Special emphasis has been placed on modelling aspects where the common elements between EMS and DMS must be modelled to cater to both types of functions. Since such a system does not have as high a degree of observability as a pure transmission system, the real-time applications such as topology/dynamic network colouring and state estimation have to be tailored to suit them. The complete suite of extended real-time and study mode functions, provide specific operational aids in maintaining security while providing an optimum economic operation. This paper discusses the modelling and functional details of such hybrid systems and practical experience gained during the implementation of such a system is presented.