The provided sources offer a comprehensive overview of Phasor Measurement Units (PMUs) and their critical role in modern power grids, with a specific focus on Denmark’s TSO, Energinet. They explain what PMUs are, detailing their ability to provide time-synchronised, high-speed measurements of electrical quantities, which significantly enhances grid situational awareness compared to traditional systems. The documents highlight numerous benefits of PMUs, including improved dynamic event detection, state estimation, and oscillation monitoring, and their importance for integrating renewable energy and validating grid models. Furthermore, the text addresses limitations and challenges associated with PMU deployment, such as the need for robust communication infrastructure and data quality management. Finally, the sources explore future advancements in PMU technology, discussing their enabling role for concepts like digital twins, dynamic balancing, and ultimately, self-healing grids, demonstrating a global trend towards more automated and resilient power systems.