Comparison of Model Parameter Derivation Accuracy Between a PMU-Based Generator Measurement System and Conventional Test Equipment: Field Demonstration at Muju Pumped-Storage Unit 1

This study evaluates the accuracy of model parameter derivation using a phasor measurement unit (PMU)-based permanently installed measurement system by comparing its results with those obtained from conventional test equipment at Muju Pumped-Storage Unit 1 (343 MVA). Seven characterization tests were conducted simultaneously using both systems, and a standard eight-step parameter estimation algorithm was applied independently to each dataset. Raw measurements exhibited minor differences (base field current 0.023%, saturation coefficients up to 0.81%). GENSAE and ESST4B model parameters were identical to three decimal places, indicating that the observed measurement differences of ≤1% did not affect the derived parameters at a single operating point of 71.2 MW (20.76% of rated capacity). PSS2A and HYGOV parameters were validated without re-derivation. A three-level comparison — measurement error (≤1%), equipment replacement effect (4–12%), and design-field discrepancy (8–50%) — shows that PMU measurement differences are approximately one order of magnitude smaller than parameter changes requiring re-determination. Within the scope of this single-unit, single-point demonstration, these findings provide preliminary evidence supporting PMU-based test exemption under Article 37 of the Korean Grid Reliability Standards.