An integrated system theoretic process analysis with multilevel flow modeling for the identification of cyber-physical hazards in a process industry

The deep integration of information technology and process industry production systems makes system failure increasingly multi-source and multi-scale. In contrast to conventional hazard methods, system theoretic process analysis (STPA) can analyze the hazards in system control processes from the perspective of interactions among the system components. Theoretically, this method offers advantages that are better suited for modern production systems. However, as of now, the integration between STPA and process industrial production systems is still lacking. To address this issue, this study improved the original STPA method. First, we propose the "5 flows" concept for the process industrial cyber-physical systems. The systems are described using multilevel flow modeling (MFM). This leads to the development of the MSTPA method, which is specifically designed to analyze the cyber-physical hazards in process industrial production systems. Subsequently, the cyber-physical hazards of a fluidized-bed catalytic cracking unit are analyzed in detail using the MSTPA method as an example. The results show that MSTPA can identify cyber-physical hazards in multiple dimensions. It is proved that, compared with the original STPA and traditional hazard methods, the MSTPA method can better identify cyber-physical hazards in process industrial production systems.