Alarm handling in supervisory control and data acquisition (SCADA) system is a critical issue in securing critical infrastructures (CIs). Each error or delay in clearing an alarm may jeopardize the reliability and security of the CI at the national level. This paper analyzes and models the SCADA alarm communication management by using the unified modeling language and colored timed Petri nets. The proposed alarm-handling model does not refer to a specific CI application and it is based on a general approach which alarm transactions are integrated with dispatcher’s commands and substation’s operator maintenance. To demonstrate the potential of the proposed alarm-handling model, a real case study in power system is simulated and some scenarios with different number of substations and error rates are analyzed.
