Shuyu Jia, Qinglai Guo
ABSTRACT The economical, stable and efficient operation of power systems is intrinsically linked to secondary systems and their diverse functional applications. With the advancement of communication technologies, control algorithms, and emerging regulatory entities, modern power systems have evolved to become more intelligent yet complex compared to traditional grids. As the conceptual framework of power system security expands from primary system safety to a holistic cyber‐physical paradigm, the functional safety of secondary systems has emerged as a critical and paramount requirement for ensuring overall grid stability and reliability. This paper systematically reviews research on functional safety analysis and mitigation strategies for secondary systems from a cyber‐physical perspective. Firstly, the basic concept and propagation mechanism of power system functional security are introduced; secondly, the research difficulties of functional security are analysed from the three dimensions of system, data and software security; then, the current research status of functional security in different dimensions is summarised; finally, we offer a forward‐looking perspective on future research directions for analysing and mitigating functional safety risks, emphasising the prevention of physical grid failures caused by secondary system anomalies from a cyber‐physical viewpoint.