Systematic Design of Automation, Protection, and Control in Substations

A design tool is proposed for the subsequent development steps of a substation control system, viz. task specification, system design, software production, and hardware implementation. Process control is characterized by properties like causality, determinism, asynchronity, stochastic events, and real-time control. All control tasks can directly be expressed in terms of a subclass of Petri nets with the above mentioned properties. The formal Petri net properties guarantee well defined interfaces (supporting task sharing), limit consequences of changes (in technology or by extension) to local alterations (i.e. reusability of the unaffected parts), permit concurrent task formulation (supporting availability and response time respectively) and facilitate formal error elimination. Moreover, the system design can be mapped via software to hardware by formal procedures.