Analisis Distorsi Harmonik untuk Penghitungan Kapasitas Derating pada Transformator Ship to Shore Crane Terminal Petikemas Belawan Fase 2

Abstract

Ports play an important role in supporting domestic and international goods distribution, one of which is Belawan Port in North Sumatra. The Belawan Container Terminal Phase 2 operates Ship to Shore (STS) Cranes equipped with a 1,250 kVA dry-type main transformer and a 150 kVA auxiliary transformer. Nonlinear loads from electric motors and Variable Speed Drives (VSD) generate harmonic distortion that affects transformer derating. This study aims to analyze the Total Harmonic Distortion of current (THDi) through direct measurement and Matlab Simulink simulation, as well as to evaluate the effectiveness of passive and active filters in reducing harmonics. The results indicate that without filters, THDi is significantly high, reaching a maximum of 91.55% in measurements and 97.45% in simulations, which poses risks of reduced efficiency and shortened transformer lifespan. The application of active filters is able to reduce THDi in the range of 2.31%–9.88% with higher flexibility to load variations, while passive filters suppress THDi up to 3.99%–14.17%. Analysis based on IEEE 519-2014 standards shows that the ideal THDi limit is 8%, whereas field measurements reached 29.07%, indicating the necessity of harmonic mitigation. Derating calculations reveal that the STS Crane transformer requires a 12% capacity reduction to ensure safe operation. Thus, the application of harmonic filters is effective in improving power quality, extending transformer lifetime, and ensuring the reliability of STS Crane operations