Utilization of the voltage rate to localization of harmonic sources in a power system
The paper proposes the new approach to determine which side, the utility or the customer is dominant harmonic source in a power system. At the beginning, review of existing approaches to localization of harmonic sources is given. Then, the theoretical background of the new approach is presented. The used criterion of localization of harmonic sources in a power system is based on examining the voltage ratio, which is defined in the paper. The results of investigation of sensibility of this ratio to the errors burdening quantities used for its calculation are analyzed. The practical conclusions are given. It is underlined that the presented approach has better properties than existing ones.
Estimation of the Utility's and Consumer's Contribution to Harmonic Distortion
A method has been presented for the allocation of responsibilities between a utility and a consumer with reference to the distortion of 3-phase voltage waveforms at the point of common coupling. The input data required for applying this method are the measured voltage and current waveforms at the point of common coupling. The frequencies in the measured waveforms are estimated and a Kalman filter is used to estimate the phasors at these frequencies. Subsequently, the parameters of the electrical system of the industrial load have been estimated using the recursive least-squares technique. With these estimated data, the individual contributions to the distortion of the 3-phase voltage waveforms have been calculated. The proposed method has been illustrated by means of a practical example.
The Determination of Physicochemical Characteristics of Biodiesel and Its Blending Oils
The viscosity,combustion heat,sulfur content,carbon residue,ash,flash point,moisture and cetane value of biodiesel and its blending oils with diesel were determined.The influence of temperature on the viscosity was studied,and the physicochemical characteristics of biodiesel and its blending oils were compared with diesel.The results indicated that biodiesel and its blending oils had some superior performances and good application prospect.