Simulation of SCADA Signals Based on the Message Structure of the IEC 60870-5-101 Tele-control Protocol

The SCADA systems are very important to control widely distributed power networks. Each SCADA system uses a tele-control protocol for communication between stations, one of the commonly used protocols is the IEC60870-5-101 standard tele-control protocol . For this study, the IEC60870-5-101 was selected to simulate SCADA signals transferring between two stations due to its wide spread use in the tele-control systems, and it is also considered as a base structure for modern tele-control systems such as IEC60870-5-104. The aim of this simulation is to study the behavior of the tele-control protocol. Visual basic programming language was used to implement this simulation. The simulation was done by taking a transformer tap changer as an example for the experiment. For this tap changer, Regulating commands from the central station (control centre) were sent to the controlled station(remote station) in order to raise or lower the tap changer position then the step position indications were sent from the controlled station to the central station. Additional SCADA functions, such as generation of alarms and implementation of interlocks, which are not present in the existing SCADA systems, were added within Centre station besides its generation in the remote station.