<p>Interoperability between systems is becoming more critical in the electric power sector as dispersed generating resources, power system intelligence, and digitalization accelerate. Many fields describe interoperability as ‘the ability to interchange effectively between systems or unit devices to offer services’, which is commonly utilized. As database sharing and data mapping for system interconnection grow, new data mapping and gateways are needed for each system interconnection, exponentially increasing interconnection time and expense. To design an interoperability level evaluation method to ensure operability, the existing status of interoperability at home and abroad is researched and Power System Interoperability Standards suitable for our circumstances are derived. KEPCO’s power systems are assessed using international standards (IEC 61850, 61970).</p>