Investigation, Identification and Mitigation of Harmonic Distortions in Power Systems

• Author / Creator

  Wang, Yang

• Harmonic distortion has always been an important power quality concern for utilities and customers. In recent years, a wide variety of harmonic-producing loads, ranging from home appliances to industrial equipment, is being connected to power systems due to rapid advancement in power electronic technology. These harmonic sources can be grouped into two categories – distributed harmonic sources and concentrated harmonic sources. Distributed harmonic sources are associated with small power-electronic-based loads such as home appliances and office equipment. They are located randomly in distribution systems. Based on extensive field measurements and analysis, this thesis reveals the harmonic distortion characteristics in current distribution systems, especially those supplying residential customers. A main impact of increased harmonic sources is the system-capacitor resonance. This thesis further proposes a scheme to damp harmonic resonance for multiple switchable capacitors using a shared damping block. This damping block is designed in such a way that it will provide adequate damping capability for all possible on/off combinations of the capacitors involved. Performance and effectiveness of the proposed scheme are demonstrated through the comparative study on actual capacitor application cases. Concentrated harmonic sources are those industrial and commercial facilities that contain a large amount of nonlinear loads. When a harmonic problem occurs in a system with several such facilities as suspects, the first step is to determine which loads cause the harmonic problem. The second part of this thesis presents two measurement-based methods that can quantify the respective harmonic contributions of multiple concentrated harmonic sources to a harmonic problem. The first method is based on multiple linear regression (MLR). The second method advances the MLR-based method by including synchronized harmonic phasor data and by adopting independent component analysis (ICA). Performances of these methods have been demonstrated using simulation verifications, lab experiments and field measurements. The proposed methods are expected to become useful tools for power quality management.

• Subjects / Keywords

  • Shunt capacitor
  • Harmonic source identification
  • C-type filter
  • Harmonic distortion
  • Multiple linear regression
  • Residential harmonics
  • Independent component analysis
  • Harmonic resonance

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3K931M39

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.