Nikitina A. An automated system of power consumption control and the assessment of quality of power processes in low voltage distributed networks

The thesis deals with the problem of low quality of electric energy in the low power distribution networks of industrial enterprises, which greatly affects the operation mode and electromagnetic compatibility of the consumers connected to these networks. The thesis contains the analysis of the issue of the peculiarities of the change of quality indicators (QI) of electric energy (EE) in the researched electric networks and promising methods of their control and determination of EE consumption in the conditions of industrial enterprises. It is proved that in the conditions of saturation of distribution networks by nonlinear consumers the dominant factor of QI deterioration consists in non-sinusoidal currents and in a number of cases also in supply voltages, against the background of rather high level of their asymmetry. The peculiarity of the calculations of energy processes in these conditions consists in the impossibility of direct use of the theory and methods applicable to their sinusoidal change, and among the existing systems of determination of electric consumption and QI of electric energy, only computer means of measurement and their low-cost microcontroller analogues for a case of the distributed measuring systems are suitable for the solution of the set tasks. As a result, the directions of improvement of existing methods and means of determination of energy consumption and QI of electric energy via the components of instantaneous power and features of development of new ones are determined, which makes it possible to introduce effective measures of automatic compensation for asymmetry and nonsinusoidality in low voltage electric networks. Improved calculated ratios for the researched components of energy consumption and electricity quality indicators are obtained. The possibility of forming payment for electricity for individual consumers depending on the main components of power that determine the energy process – active, reactive and distortion power is determined. The efficiency of identification with the help of the developed mathematical support of single-phase and three-phase consumers that distort the quality of energy processes in low-voltage distribution networks based on the control of certain QI in individual network nodes is proved. The ways of realization of the developed methods and means as a part of automatic system of technical accounting of the electric power are determined and features of its construction and effective use are revealed. The reliability of the theoretical propositions obtained in the thesis is confirmed by the results of mathematical and physical modeling, experimental research and experimental testing in industry.