ANALYSIS OF HARMONICS ON HOUSEHOLD GENERATORS

ABSTRACT

This research work is aimed at studying the effect of harmonics in house hold generators, which was carried out by performing harmonic test using resistive, capacitive and inductive loads on a series connection to an alternating current source, performing harmonic test using resistive, capacitive and inductive loads on a series connection to different ratings of household generator power source and Introduce harmonic reduction method such as a passive LC filter into the system. The method of harmonic investigation analysis was done with different household generators with various loads to vary the resistive, inductive and mixed loads. The capacitive load was not included in the tests as they were not available at the time of the tests. These harmonics were reduced by designing passive LC filter using Series Resonance. During series resonance, the inductive reactance of system components (such as transformers) is equal to the capacitive reactance of system components (such as cables or capacitor banks). Upon comparing the result of total harmonics distortion without passive LC filters and determination of harmonics in household generators in-cooperated with filters, various observations were made as follows. In all the three generator models tested it was observed that the no load THD for the higher rated generator models were lower than 750VA model. It was also observed that inductive loads used (eg 75W electric fan) have higher THD than resistive loads. This was due to the fact that inductive loads generate more harmonics than resistive loads followed by the energy saving bulbs that oscillator in their circuits and this tends to cause harmonics too. ix The higher rated generators have better THD values overall which can be attributed mostly to good automatic voltage regulators (AVR) and output impedance matching between source to load.