Examine advanced battery energy storage systems transforming grid stability through millisecond-response frequency regulation and multi-MW ramp rate control. Learn how BESS provides synthetic inertia for renewable-heavy grids, delivering primary frequency response within 100-500ms while managing power fluctuations from variable generation. Understand virtual power plant architectures aggregating distributed storage assets for coordinated grid services, including capacity firming, peak shaving, and ancillary market participation. Review control algorithms for state-of-charge optimization, degradation management, and revenue stacking across energy arbitrage and regulation markets. Discuss grid code compliance, communication protocols for TSO integration, and economic modeling of storage deployments. Essential for grid operators, project developers, and system integrators implementing utility-scale storage solutions.