Popov A. Analysis of Ferroresonance Processes in 6 kV Distribution Networks and Methods for their Damping

Object - ferroresonance processes in the electrical networks 6 kV with iso-lated neutral point and the voltage transformers of different types. Aim - increasing the reliability of the work of voltage transformers using for insulation checking by limiting the action of ferroresonance phenomena, development the methods of the analysis of ferroresonance processes for predicting the risk of the appearance of ferroresonance and its prevention in the electrical networks 6 kV with the isolated neutral point. Methods - fundamental laws of electrical engineering, the theory of linear and nonlinear circuits, the methods of the mathematical simulation, experimental methods, the methods of mathematical statistics and planning of experiment, the methods of physical simulation in the research efficiency of the proposed device for ferroresonance damping. Novelty - are created the simulation models, which can be used for a study of the effectiveness of the protection devices from the ferroresonance, for establishment of the range of the parameters of network 6 kV, with which is possible the evolution of the ferroresonance phenomena, which is different from the known the ability to determine minimally necessary active power and ballast resistance, required for damping of ferroresonance oscillations;analyzed the phenomenon of ferroresonance taking into account the scatter of the magnetization characteristics of voltage transformers and proved dependence between the domain of existence of steady ferroresonance and the parameters of these characteristics; is developed the experimental method of determining the magnetization characteristics of the measuring voltage transformers, in which as the power source is used the charged capacitor, which is different from the known by the fact that for its realization don't need to use an additional (measuring) winding; is developed the method of the identification of the ferroresonance mode based on the spectral analysis of the voltage 3u0, which is different from the known for the ability to simultaneously distinguish subharmonic ferroresonance, and also the ferroresonance at the frequencies 50 Hz and above. The results of dissertation work can be used for the determination of the parameters of electrical network, with which is possible the establishment of ferroresonant oscillations and with which it is necessary to inject means of protection from the ferroresonance, during the development of the algorithms of the identification of nonstationary modes, with the creation of the devices for protection from the ferroresonance, in particular, the obtained results can be used in all electrical networks with the insulated neutral point with a voltage of 6 kV.