Analysis of UFR Criteria Based on System Analysis According to Expansion of Renewable Energy

As the penetration of Variable Renewable Energy (VRE) increases, the power system may face risks of frequency decline due to the degradation of system inertia and an increase in the Rate of Change of Frequency (RoCoF). The negative impact on frequency stability highlights the importance of establishing Under Frequency Relay (UFR) as well as defining procedures and criteria for frequency decline protection. For UFR analysis, real performance data is extracted based on the current electrical facilities and loads connected to the system. By reflecting this extracted data, system constants are calculated, and through these constants, frequency computations over time are conducted to establish optimal operating strategies for UFR. In other words, current methods of establishing UFR standards are based on real data. However, this paper analyzes UFR standards in operation using the Power Simulation Simulator for Engineering (PSS/E), a large-scale power system analysis program, establishes an optimal UFR operation plan for the system, and targets future systems that are planned but not yet connected