A Systematic Approach for Medium-Voltage Power Factor Correction Design

The value proposition for the installation of power factor (PF) correction (PFC) to avoid costly utility penalties is easily understood. The attractive payback of such PFC opportunities often pushes the project ahead without engineering considerations. In the case of medium-voltage PFC, lack of upfront engineering can lead to unexpected consequences in the performance of the PFC equipment ranging from nuisance trips and blown fuses to catastrophic failure in the extreme. In this paper, the authors propose a systematic approach to the design of PFC for medium-voltage systems. Three actual case studies were selected to illustrate this systematic approach and show that it can be applied regardless of the size, type, and complexity of the facility. Such a methodology is composed of load flow and harmonic measurements, harmonic analysis, utility billing demand and PF analysis, and reactive compensation specification in the form of either capacitors or harmonic filters, if needed. Diverse and competing design constraints, including daily and week load cycles, nearby utility capacitors, switched or stepped requirements, specifics of utility tariffs, loads with high harmonic content, and harmonic resonance, are identified, analyzed, and then incorporated into the solution to ensure successful performance of the PFC equipment.