Analytical Study for Determining the Harmonic Distortion Responsibility in Distribution Systems

Industrial processes are heavily automated, to improve their manufacturing efficiencies and performances. The result of this trend is that the industrial customers of electric power introduce highly nonlinear loads to the power distribution system, due to the excessive use of power electronic equipment's. This can introduce a large amount of harmonic distortion throughout the system. Since the distribution systems are including different categories of loads, the contributions of waveform distortion between the utility and the customer are of growing interest. Power components such as active, reactive and apparent power are well defined under sinusoidal balanced systems. At present, the definitions and physical meanings of power components are still debatable, so none of the approaches can lead to power component definitions, which satisfy all required power properties under non-sinusoidal conditions. Due to this reason, it is important to determine precisely the magnitude and direction of energy and power for each harmonic order; in case of non-sinusoidal condition the thesis suggests an approach in power theory. The idea of this approach has been inspired from the concept of instantaneous power. The thesis concerns with this matter, and aim towards the development of an adequate method dealing with the possibility of determining the responsibility of the harmonic distortion and focusing on the problem of interactions between the utility distortion and the customer distortion. This method can be used for billing purposes to control harmonic distortion levels in Distribution systems. A software program has been developed, using MATLAB, in order to perform the study in an easy way to deduce all harmonic power components (outputs) while fed with direct measurement of external periodic signals of voltage and current (input data). Now, the voltages and currents measured at the Point of Common Coupling (PCC) are sufficient for determining the magnitude and direction of power for each harmonic order. This developed method can be implemented in any power quality measurement device, which monitors the voltage and current harmonics (amplitudes and phase angles) simultaneously