Energy loss due to harmonics in residential campus — A case study

Harmonics are the by-products of modern electronic devices i.e. nonlinear loads which create harmonics by drawing current in abrupt short pulses, rather than in a smooth sinusoidal manner. Any distribution circuit feeding nonlinear loads will contain some degree of harmonic frequencies. Due to the rapidly increasing number of non-linear loads in distribution systems, the harmonic distortion of the current and voltage increases. Examples of non-linear loads are personal computer, laser printer, television set (TV), fluorescent tube with electronic ballast, compact fluorescent lamp, battery charger, uninterrupted power supply (UPS) and any other equipment powered by switched-mode power supply (SMPS) unit. The harmonic distortion produced in residential buildings has not been given proper attention as linear loads were predominant earlier. As the number of harmonics-producing loads in residences has increased over the years, it has become increasingly necessary to address their effects on the distribution system. Power Quality of distribution networks is severely affected due to the flow of these generated harmonics. Harmonic currents generated by nonlinear loads can cause problems in the power system. These harmonics can cause excessive heat in many appliances, and hence reduce the life span of the distribution transformer supplying such loads. It can also increase power consumption and reduce system efficiency. It also lowers the system power factor, resulting in penalties on monthly utility bills. This paper presents the results of a case study of harmonic distortion caused by linear and non linear home appliances. An attempt has been made to calculate the energy losses of a residential campus comprising of 100 houses, due to harmonic distortion caused by linear/non- linear loads. The scope of work includes measurement and analysis of percentage total harmonic distortion which is found in the range of 50 to greater than 200. The reactive power contributed by these appliances which results in poor power factor of the distribution system is also studied and remedies are suggested to improve the power factor.