As 189 grid-management substations nationwide have, starting in 2026, been restricting new interconnection of renewable energy and large-scale demand through conditional curtailment, long-duration ESS (Energy Storage System) is shifting from a simple generation-consumption buffer into an essential variable in grid interface design. Korea's Ministry of Trade, Industry and Energy's centralized-contract market has presented a target of securing approximately 0.5 GW annually from 2026 to 2029, and a cumulative 21.5 GW by 2038, of long-duration ESS, which translates directly into standardization pressure on the communication and response specifications across the three-tier BMS-PCS-EMS hierarchy. In the current structure, where grid-interconnection queue information is not disclosed, designing margin into an individual ESS system's…