Harmonics estimation and modeling of residential and commercial loads

The distortion in the voltage and current waveforms deteriorates the performance of the equipment/devices connected in the distribution systems. The analysis of the harmonics is essential to determine the performance and designing of these equipment and optimal location of the harmonic mitigation devices. In this paper a preliminary survey has been carried out in the domestic and commercial areas to identify the existing level of current and voltage harmonic and their characteristics for different type of residential and commercial loads. The voltage and current waveforms of some of the commonly used loads and their harmonics have been recorded using power analyzer and digital storage oscilloscope. The total harmonic distortion is used as a harmonic index to identify the effects of different nonlinear loads. The detail mathematical modeling of the personal computer type load is established to estimate the harmonic contents of such loads. To verify their characteristics whether the nonlinear loads behave like current-type or voltage-type harmonic source, some nonlinear loads are simulated and validated experimentally.