Harmonic activity estimation and harmonic analysis of office equipment

Increasing use of electronic equipment and computers in office buildings has raised harmonicproblems in low voltage distribution systems. Harmonics may cause unreliable operation ofdistribution systems, malfunction of equipments, and likewise reduce the efficiency and lifeexpectancy of connected equipments. In office buildings, one of the main harmonic sources isa large number of computer loads. Especially, personal computers cause harmonic distortionsto their supply system. In order to minimize losses and to design a reliable system, analyzingthe harmonics gains importance. System components should be properly modeled to performa proper harmonic analysis.In this study, office equipments, especially PCs, are analyzed in details and the necessarymeasurements, modeling and evaluation procedures are applied. In considerations ofmodeling procedures, all measurements of equipments are realized under laboratoryconditions.The nonlinear characteristics of office equipments are obtained with the help of measurementsand proper nonlinear models are developed. Various MATLAB coded programs havedeveloped for modeling based on the Newton-Raphson Iterative Method and the results havecrosschecked with the Simulink simulations. Simulink models of the office equipments areformed and simulations are carried out in time and frequency domain.In numerical application, a three-storey medium size office building with PC loads andlighting systems is modeled with the proposed current injection method and Fouriertransforms are applied. In addition, the symmetrical components theory is implemented undernonsinusoidal conditions and power quantities for nonsinusoidal situations and unbalancedloads are calculated .In this research, the current distributions, voltage distributions and harmonic activities can beobtained for both the phase and neutral lines with the help of developed and proposed models.All of the calculations, evaluations, models and analyses are implemented with MATLABsoftware and Simulink toolboxes.Keywords: Office equipment, personal computers, harmonic load, harmonic activity,harmonic analysis, nonsinusoidal power definitions, harmonic energy, nonlinear resistancemodel, current injection model, MATLAB.JURY:1. Doç. Dr. Osman KILIÇ (Supervisor) Date: 29.08.20062. Prof. Dr. Celal KOCATEPE Page: 2783. Doç. Dr. Nurettin UMURKAN4. Prof. Dr. Fahrettin ARSLAN5. Prof. Dr. Nizamettin AYDIN