Heat, ventilation and air conditioning (HVAC) systems or district cooling plants are key functions of modern buildings for optimum indoor environmental comfort. The key components of HVAC systems or district cooling plants are chillers, compressors, centrifugal pumps and fans. They are designed for peak load conditions. As they are often not fully loaded, significant energy savings could be achieved by controlling the flow speed. Plant designers often choose variable speed drives (VFDs) as a tool to control the flow speed of the HVAC systems or district cooling plants. However, it is common knowledge that these AC drives are the main source of harmonic currents. Sensitive electrical components operating in erratic environments under harmonic distortions may break down unexpectedly and result in discomfort and costly repairs. High harmonic currents can also jeopardize the reliable operation of emergency diesel gensets.