Transients and ferroresonance in single phase transformers, being a study of methods of analytical and numerical calculations of the transient and ferroresonance phenomena including the nonlineaxity and hysteresis effects

Initially the fundamental equations are derived from the physical system which provide a basis to draw the equivalent circuit diagram. Then the previous analytical and numerical works on transient current and ferroresonance phenomena are reviewed and the aim of the present investigation is given in Chapter 1. In order to reduce the number of circuit parameters, the parameters are generalized making use of the "standard coefficients". Thus, in Chapter 2 the differential equations obtained in Chapter 1 are put into new forms. Since there are a number of methods of representing the B/H characteristics the possibilities are compared at the beginning of Chapter 3 to choose the most suitable one. To estimate the coefficients of the functions representing the characteristics the experimental B/H pattern is required. Therefore, the method used to obtain these characteristics is explained. The main purpose of Chapter 3 is actually to calculate the transient current. So analytical and numerical techniques are developed. In Chapter 4 fundamental ferroresonance is investigated. To visualize the jump phenomena a graphical solution is presented and used to predict the jump points. To achieve more accurate results, additional terms are included in the expressions of flux linkages. Subharmonic ferroresonance is, in fact, a part of ferroresonance but, since its nature differs from fundamental ferroresonance, it is studied separately in Chapter 5. In this chapter, using the Preisach model and experimental series method for the B/H representation, the hysteresis effect on subharmonic ferroresonance is examined. By an analytical method the stability of this phenomenon is investigated. Although there is "analysis" and "comparisons" sections at the end of each chapter, general conclusions are drawn and some suggestions are made for the future work in Chapter 6. All the explanatory figures are located in the text side and the experimental and computed figures are presented in a separate "diagrams" section.Initially the fundamental equations are derived from the physical system which provide a basis to draw the equivalent circuit diagram. Then the previous analytical and numerical works on transient current and ferroresonance phenomena are reviewed and the aim of the present investigation is given in Chapter 1. In order to reduce the number of circuit parameters, the parameters are generalized making use of the "standard coefficients". Thus, in Chapter 2 the differential equations obtained in Chapter 1 are put into new forms. Since there are a number of methods of representing the B/H characteristics the possibilities are compared at the beginning of Chapter 3 to choose the most suitable one. To estimate the coefficients of the functions representing the characteristics the experimental B/H pattern is required. Therefore, the method used to obtain these characteristics is explained. The main purpose of Chapter 3 is actually to calculate the transient current. So analytical and numerical techniques are developed. In Chapter 4 fundamental ferroresonance is investigated. To visualize the jump phenomena a graphical solution is presented and used to predict the jump points. To achieve more accurate results, additional terms are included in the expressions of flux linkages. Subharmonic ferroresonance is, in fact, a part of ferroresonance but, since its nature differs from fundamental ferroresonance, it is studied separately in Chapter 5. In this chapter, using the Preisach model and experimental series method for the B/H representation, the hysteresis effect on subharmonic ferroresonance is examined. By an analytical method the stability of this phenomenon is investigated. Although there is "analysis" and "comparisons" sections at the end of each chapter, general conclusions are drawn and some suggestions are made for the future work in Chapter 6. All the explanatory figures are located in the text side and the experimental and computed figures are presented in a separate "diagrams" section