Recent growth in deployment of distributed energy resources (DERs), energy storage systems, and advanced grid control schemes have increased the levels of variability in generation and load conditions over the transmission and distribution system. Large scale decentralization of electricity production and rise in the adoption of independently operable (micro-) grids has made it even more difficult to control load or generation perturbations caused by production or consumption variability. Complementary to the traditional Supervisory Control and Data Acquisition (SCADA) based control, modern grid control based on much faster measurements such as time-synchronized phasor data has proved to be promising to provide additional robustness. Two unique use cases will be used to present the modern grid challenges and discuss solutions. The first is the issue of spinning reserve due to variations in renewable energy, mainly PV cloud events. The second is the issue of sudden reverse power flow into the power station in systems with high renewable penetration and unprecedented sudden load loss.