Survey of harmonic distortion from power quality measurements and the application of standards including simulation

Power quality is of ever growing concern to utilities and customers. The problem associated with high harmonic content in the power system not only results in poor quality of supply but also the operation of the system will get affected. Based on the specific case studies conducted at an industry, which manufactures different brakes for four wheelers, it was observed that 5th and 7th harmonics are predominant. The observations were made at pillar hardening, MIG welding, induction hardening, zinc plating rectifier etc., the issues of current and voltage harmonics are analyzed. Field measurements conducted at various location in the plant were used to develop models for the steady state harmonic analysis of the entire plant. Power flow analysis under study was performed using relevant software and is found that the power factor is identical with measured value. Using PSPICE software the current waveforms are generated at various stages in the industries in order to be identical with the field measurements taken. Field measurements are useful in the design of shunt filter, which is a combination of capacitance and inductance, is used to improve the power factor and harmonics suppression which is in accordance with IEEE 519-1992 to meet the limits on individual distortion and THD. Shunt filter is designed to improve power factor from 0.74 to 0.9. Current THD is reduced considerably.