Implementation of the Automatic Line Reclosure using PLC and Petri Nets Modelling

This paper presents an implementation of the line recloser automation sequence using PLC (Programable Logic Controller). The modelling of the automation process is done using the ordinary Petri Nets. There are presented several models corresponding to different line reclosure schemes. Then the implementation of the simpliest model model is done using Grafcet Language (the PLC programming language which becomes one of the most used language in the discreteand sequencial automation). An equivalance between PN modelling and Grafcet language is presented also here. This implementation represents an alternative to the classical hardwired reclosure automation scheme, (used even today in medium voltage networks), PC based softwares that runs on the servers in high voltage substations or dedicated (but rigid) functions existing in the expensive numerical protection relays.