Analysis of time-varying harmonics in electrical distribution systems
This thesis analyzes the time-varying nature of fundamental and harmonic signals in electric power distribution systems. Measurements show that signal variations are neither completely deterministic nor random. As a consequence the deterministic and random parts are analyzed separately. Two methods are employed to extract the deterministic and random parts. One method extracts the deterministic part using regression analysis, and the remaining random part is expected to resemble the normal distribution. A procedure for obtaining the distribution of the peak voltages is presented. In the second method, wavelet transforms is applied to harmonic signal variations. The Discrete Wavelet Transform is used to quantify harmonic changes with time. Experimental data of fundamental and harmonic currents are analyzed both methods and the results presented. The thesis concludes with the potential applications of the proposed techniques.