Electromagnetic Transient Analysis and Novel Protective Relaying Techniques for Power Transformers

1 Introduction: Transformer differential protection principle and existing problem analysis 1.1 Introduction 1.2 Fundamentals of transformer differential protection 1.3 Some problems about power transformer main protection 1.4 Analysis of Electromagnetic Transient and Adaptability of Second Harmonic Restraint Based Differential Protection of UHV Power Transformer 1.5 Study on comparisons among some waveform symmetry principle based transformer differential protection 1.6 Summary 2 Malfunction mechanism analysis due to nonlinearity of transformer core 2.1 Introduction 2.2 The ultra-saturation phenomenon of loaded transformer energization and its impacts on differential protection 2.3 Studies on the unusual maloperation of transformer differential protection during the nonlinear load switch-in 2.4 Analysis of a sort of unusual mal-operation of transformer differential protection due to removal of external fault 2.5 Analysis and countermeasure of abnormal operation behaviors of the differential protection of converter transformer 2.6 Summary 3 Novel analysis tools on operating characteristics of Transformer differential protection 3.1 Introduction 3.2 Studies on the operation behavior of differential protection during a loaded transformer energization 3.3 The Comparative investigation on current differential criteria between the one using phase current and the one using phase-phase current difference for the transformer using Y-delta connection 3.4 Comparative analysis on current percentage differential protections using a novel reliability evaluation criterion 3.5 Comparative studies on percentage differential criteria using phase current and superimposed phase current 3.6 A novel analysis methodology of differential protection operation behaviour 3.7 Summary 4 Novel magnetizing inrush identification schemes 4.1 Introduction 4.2 Studies for identification of the inrush based on improved correlation algorithm 4.3 A novel method for discrimination of internal faults and inrush currents by using waveform singularity factor 4.4 A new principle of discrimination between inrush current and internal fault current of transformer based on self-correlation function 4.5 Identifying inrush current using sinusoidal proximity factor 4.6 A wavelet transform based sheme for power transformer inrush identification 4.7 A novel adaptive scheme of discrimination between internal faults and inrush currents of transformer using mathematical Morphology 4.8 Identifying transformer inrush current based on normalized grille curve 4.9 A novel algorithm for discrimination between inrush currents and internal faults based on equivalent instantaneous leakage inductance 4.10 A two terminal network-based method for discrimination between internal faults and inrush currents 4.11 Summary 5 Comprehensive countermeasures on improving the performance of transformer differential protection 5.1 Introduction 5.2 A method to eliminate the magnetizing inrush current of energized transformers 5.3 Identification of cross-country fault of power transformer for fast unblocking of differential protection 5.4 Adaptive scheme in the transformer main protection 5.5 A Series Multi-resolution Morphological Gradient based Criterion to Identify CT Saturation 5.6 A new adaptive method to identify CT saturation using grille fractal 5.7 Summary