This paper provides a comprehensive review of the key applications and technological evolution of communication technologies in the field of relay protection in recent years, with a focus on the integration patterns and performance characteristics of optical fiber communication . This paper provides a comprehensive review of the key applications and technological evolution of communication technologies in the field of relay protection in recent years, with a focus on the integration patterns and performance characteristics of optical fiber communication . With the deep integration of smart grids and information and communication technologies, power system relay protection is undergoing a fundamental transformation from traditional localized, closed architectures to communication-based, distributed, and collaborative intelligent protection systems. able sources such as wind and solar. These clean energy sources, connected through inverters and flexible transmission systems, are transforming traditional grids based on synchronous generators into more flexible cant challenges to system stability. Nowhere is that clearer than in the challenge to. localized, closed architectures to communication-based, distributed, and collaborative intelligent protection systems. The incorporation of communication technologies has significantly enhanced the real-time performance and accuracy of fault detection, information exchange, and coordinat d. Relay protection systems are essential in maintaining the safety and reliability of modern electrical grids. With the open access of a large number of distributed generation, DC transmission and electric vehicles, a new deep low-carbon power system dominated by power electronic devices has. The global energy transition is ushering in a new era of power electronic-dominated grids (PEDGs), to complement the increase in the widespread integration of renewable sources like wind and solar.