HARMONIC CANCELLATION OF HYBRID LOADS IN RESIDENTIAL AND COMMERCIAL INSTALLATION

Nowadays, Non-linear loads are widely used in residential and commercial applications. This nonlinearity distort the drawn source current which injects harmonics to the electric grid. These harmonics negatively affect not only the electric grid at the point of common coupling but also affect the load itself in different ways. Harmonic currents limits are set by international standard IEC 61000 and IEEE 519 to protect the network from the high level of harmonics injected by the customer loads. These loads have low power like LED lamps, Computers, printers, TV sets, Florescent and incandescent lamps, however the residential and commercial loads represent above 70% of the total load supplied by the electric network. For this reason the overall impact on power quality indices of the network is negative. As the loads are different in nature, the drawn current is different in terms of harmonic currents amplitude and phase shift. In some cases, this diversity may lead to natural harmonic cancellation for load combined together due to the diversity factor. By other word, Harmonic requirements for a specific load are supplied by another load connected together away from the supply leading to improved resultant source current with lower harmonic contents. In this research, power analysis for individual home appliance loads is carried out to assess and evaluate the nonlinearity nature of each load and also analysis conducted for combined or hybrid loads. Lighting lamps loads are assessed together with better power quality indices for the combination rather than the individual lighting loads. Similarly, all home appliance loads are combined together. The resultant power factor is improved and current THD is decreased due to the concept of diversity phenomena. Recommendations for the residential building electrical installation designer and load manufacturer are presented as a conclusion at the end of this paper.