pierengineering

Any devices with nonlinear voltage-current characteristics generate harmonics. The main sources of harmonics in industrial and commercial power systems are static power converters used as rectifiers for various industrial processes and for other applications such as adjustable/variable speed drives, uninterruptible power system (UPS), chargers, switched-mode supplies, static frequency converter, cycloconverters, etc.

Arc furnaces and saturated magnetic devices are also harmonic sources. Since nonlinear devices represent an ever-increasing percentage of the total load in industrial and commercial electrical power distribution systems, harmonic studies become an important part of overall system design and operation.

Fortunately, the available software for harmonic analysis has also grown. Guidelines for the acceptance of harmonic distortion at Point of Common Coupling (PCC) level are defined in IEEE Std 519™, and the inter-harmonic effects to voltage flickers at other system levels are also discussed. By modeling power system impedances as a function of frequency and harmonic sources as injecting currents or forced voltages, a harmonic study can be made to determine the effect of the harmonic contributions from nonlinear loads on the voltages and currents in the power system.

Reference Standard: IEEE Std 3002.8, IEC TR 61000-3-6, IEEE 18, IEEE 519

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