This lecture note outlines the principles of power systems communication and control, covering topics such as transmission line theory, power line communication (PLC), and control mechanisms for power generation. Type of medias and network topologies in communications provide different opportunities to advance the speed, security, dependability, and sensitivity of protection relays. There are a several types of. The market, valued at $18. 8 billion in the base year of 2025, is forecasted to achieve a Compound Annual Growth Rate (CAGR) of 4.