InhaltsangabeAbout the Authors ix Preface xi 1 Principles of Transformer Differential Protection and Existing Problem Analysis 1 1.1 Introduction 1 1.2 Fundamentals of Transformer Differential Protection 2 1.2.1 Transformer Faults 2 1.2.2 Differential Protection of Transformers 3 1.2.3 The Unbalanced Current and Measures to Eliminate Its Effect 5 1.3 Some Problems with Power Transformer Main Protection 7 1.3.1 Other Types of Power Transformer Differential Protections 7 1.3.2 Research on Novel Protection Principles 9 1.4 Analysis of Electromagnetic Transients and Adaptability of Second Harmonic Restraint Based Differential Protection of a UHV Power Transformer 17 1.4.1 Modelling of the UHV Power Transformer 18 1.4.2 Simulation and Analysis 20 1.5 Study on Comparisons among Some Waveform Symmetry Principle Based Transformer Differential Protection 27 1.5.1 The Comparison and Analysis of Several Kinds of Symmetrical Waveform Theories 27 1.5.2 The Theory of Waveform Symmetry of Derivatives of Current and Its Analysis 28 1.5.3 Principle and Analysis of the Waveform Correlation Method 32 1.5.4 Analysis of Reliability and Sensitivity of Several Criteria 33 1.6 Summary 36 References 36 2 Malfunction Mechanism Analysis due to Nonlinearity of Transformer Core 39 2.1 Introduction 39 2.2 The Ultra-Saturation Phenomenon of Loaded Transformer Energizing and its Impacts on Differential Protection 43 2.2.1 Loaded Transformer Energizing Model Based on Second Order Equivalent Circuit 43 2.2.2 Preliminary Simulation Studies 48 2.3 Studies on the Unusual Mal-Operation of Transformer Differential Protection during the Nonlinear Load Switch-In 57 2.3.1 Simulation Model of the Nonlinear Load Switch-In 57 2.3.2 Simulation Results and Analysis of Mal-Operation Mechanism of Differential Protection 62 2.4 Analysis of a Sort of Unusual Mal-operation of Transformer Differential Protection due to Removal of External Fault 70 2.4.1 Modelling of the External Fault Inception and Removal and Current Transformer 70 2.4.2 Analysis of Low Current Mal-operation of Differential Protection 72 2.5 Analysis and Countermeasure of Abnormal Operation Behaviours of the Differential Protection of the Converter Transformer 80 2.5.1 Recurrence and Analysis of the Reported Abnormal Operation of the Differential Protection of the Converter Transformer 80 2.5.2 TimeDifference Criterion to Discriminate between Faults and Magnetizing Inrushes of the Converter Transformer 86 2.6 Summary 95 References 95 3 Novel Analysis Tools on Operating Characteristics of Transformer Differential Protection 97 3.1 Introduction 97 3.2 Studies on the Operation Behaviour of Differential Protection during a Loaded Transformer Energizing 99 3.2.1 Simulation Models of Loaded Transformer Switch-On and CT 99 3.2.2 Analysis of the Mal-operation Mechanism of Differential Protection 102 3.3 Comparative Investigation on Current Differential Criteria between One Using Phase Current and One Using Phase-Phase Current Difference for the Transformer using Y-Delta Connection 109 3.3.1 Analyses of Applying the Phase Current Differential to the Power Transformer with Y/Delta Connection and its Existing Bases 109 3.3.2 Rationality Analyses of Applying the Phase Current Differential Criterion to the Power Transformer with Y/Delta Connection 113 3.4 Comparative Analysis on Current Percentage Differential Protections Using a Novel Reliability Evaluation Criterion 117 3.4.1 Introduction to CPD and NPD 117 3.4.2 Performance Comparison between CPD and NPD in the Case of CT Saturation 118 3.4.3 Performance Comparison between CPD and NPD in the Case of Internal Fault 121 3.5 Comparative Studies on Percentage Differential Criteria Using Phase Current and Superimposed Phase Current 123 3.5.1 The Dynamic Locus of p - 1p +1 in the Case of CT Saturation 123 3.5.2 Sensitivity Comparison betw

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Xiangning Lin, Professor, College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, China. Prof. Lin was the first to discover the ultra-saturation phenomenon of power transformer and he designed operating characteristics analysis planes to make clear the advantages and disadvantages of existing differential protection of power transformer. He invented a variety of novel protection algorithms for the main protection of the power transformer. A series of papers were published in journals including IEEE Transactions on Power Systems and IEEE Transactions on Power Delivery. The work has been widely acknowledged and cited by international peers. He also pioneers the introduction of modern signal processing techniques to design the protection criteria for power transformer. He was the winner of the 2nd Class National Natural Science Award in 2009. He has published nearly 200 papers and books (in Chinese), he also owns over 15 patents. Jing Ma, Associate Professor, School of Electrical and Electronic Engineering, North China Electric Power University, Beijing, China. Prof. Ma was the first to apply the two-terminal network algorithm to the areas of power system protection. The work has been widely acknowledged and cited by international peers. He also proposed an approach based on grille fractal to solve the TA saturation problem, and the related paper has been published in the IEEE Transactions on Power Delivery. The research results were used in many practical engineering projects. Dr. Qing Tian, Senior Engineer with the Maintenance and Test Center of EHV Transmission Co. Ltd, Southern Power Grid, Guangzhou, China. Dr. Hanli Weng, Senior Engineer with Three-Gorge Hydropower Plant, China Yangtze Power Co., Ltd. Both have been working in this area since 1995. Their main research fields include power system operation analysis and control, voltage and reactive power optimization, power system reliability and risk assessment and power system energy saving assessment and planning.

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