Consistency Verification of Frequency Maintenance Criteria Based on Minimum Level of Inertia in South Korea

With the increase in inverter-based resources, maintaining system stability has made frequency maintenance criteria an important factor. In South Korea, there are two frequency maintenance criteria for N-1 and N-2 contingency faults, and consistency between these criteria is necessary to ensure the rational use of limited frequency response resources. This article proposes a method to verify the consistency of the criteria based on the minimum inertia in the system. The proposed methodology has the following salient features: i) developing a methodology to verify consistency between criteria based on minimum system inertia, ii) identifying the inconsistency in South Korea's existing frequency maintenance criteria and the need for their revision, iii) evaluating the impact of inconsistent frequency maintenance criteria on non-synchronous generation and system non-synchronous penetration. The methodology was validated on the IEEE 39 bus test system and applied to 7040 hourly operational data from the energy management system of the South Korean to verify the differences in criteria. The main result is that the two frequency maintenance criteria are inconsistent, require more frequency response resources in the N-1 criterion. The findings provide practical implications for system planners and operators, highlighting the need for frequency maintenance criteria revision in South Korea.