Effect of load current harmonics on vibration of three-phase generator

Abstract

Almost all today electrical loads are considered non-linear such as switch mode power supply (SMPS) for powering computer and mobile phone or variable speed drive (VSD) for driving home and industrial electric motors. These loads generate ac non-sinusoidal current containing a lot of harmonics as indicated by its high total harmonics distortion (THD) figure. Current harmonics bring negative effects into all electrical power system components, including three-phase generator. This paper provides analysis of load current harmonics effects on vibration of three-phase generator. Three different laboratory experiments have been conducted i.e. three-phase linear resistive loading, non-linear loading with a three-phase ac/dc converter and non-linear loading with three single-phase capacitor filtered ac/dc converters. Results show that the higher load current harmonics content the higher is vibration of the three-phase generator. Non-linear loading with a three-phase ac/dc converter that generate about 24.7% THD gives an increase of 4.3% and 5.5% in average of vertical and horizontal vibrations of the three-phase generator respectively. Further, non-linear loading with three single-phase capacitor filtered ac/dc converters that generate THD as high as 74.9% gives significant increase of 28.1% and 23.6% in average of vertical and horizontal vibrations respectively.

PENGARUH HARMONISA ARUS AKIBAT PENGGUNAAN BEBAN NON-LINIER TERHADAP HASIL PENGUKURAN kWhmeter ANALOG

“…Gelombang harmonisa juga berdampak terhadap meningkatnya vibrasi generator sehingga menambah besar rugi mekanik dan pada akhirnya menurunkan efisiensi generator. Sementara itu harmonisa pada transformator akan mengakibatkan bertambahnya rugi-rugi inti (histerisis dan arus pusar) serta rugi-rugi simpangan magnetik (stray magnetic losses) dan tembaga pada belitan [12], [13], [14]. Dampak buruk harmonisa terhadap alat-alat ukur yang terpasang pada sistem kelistrikan adalah terjadinya kesalahan pengukuran jika alat-alat ukur yang terpasang tidak bekerja dengan baik untuk gelombang tegangan atau arus yang mengandung harmonisa.…”