Controlling harmonics from nonlinear loads in commercial facilities

Nonlinear loads are becoming a larger percentage of the total load in commercial facilities. Fluorescent lighting has always resulted in some harmonic generation. Now, single phase power electronic loads are a major portion of the load in many commercial facilities. They have become a problem for neutral conductors, transformer heating, and interference with other loads on the facility. Besides, single phase electronic equipment, many adjustable speed drives are now commonly applied for HVAC equipment. UPS equipment can have similar characteristics to the ASDs. The combination of these different nonlinear loads can also result in excessive injection of harmonic components from the customer facility onto the utility power system. Harmonic problems can be solved by controlling the harmonics in the loads themselves, through filtering (active or passive) on the electrical system, or by rating the system components to handle the harmonic levels. This paper discusses the expected harmonic levels in a facility as a function of the amount of nonlinear load of the different types. Alternatives for reducing harmonic distortion levels are discussed