Boxue Du, PhD, is Professor and Director-Founder of the Institute of High Voltage at the School of Electrical and Information Engineering, Tianjin University, Tianjin, China. He sits on the boards of numerous high-impact journals, including High Voltage, The Journal of Electronics and Advanced Electrical Engineering, and Insulation Materials and Electrical Engineering. He is a Fellow of the IET and a member of multiple standards committees in IEEE. Zhonglei Li, PhD, is Associate Professor at the Key Laboratory of Smart Grid of Education Ministry, School of Electrical and Information Engineering, Tianjin University, Tianjin, China. He has published widely on polypropylene cable insulation and related subjects, and he is a Member of IEEE.

• About the Author xiPreface xiiiAcknowledgements xv1 Introduction 11.1 Background 11.2 State of the Art of PP Modification Method 61.2.1 Nanocomposites 61.2.2 Polymer Blending 91.2.3 Chemical Copolymerization and Grafting 101.2.4 Crystallization Regulation 111.3 Effect of Microstructures on Dielectric Properties 131.3.1 Effect of Molecular Chain Structures 131.3.2 Effect of Aggregate Structures 151.4 Effect of Operating Conditions on Dielectric Properties 171.4.1 Effect of Aging Treatment 171.4.2 Effect of Thermal Stress 181.4.3 Effect of Voltage Stress 181.5 Content of This Book 19References 21Part I Polypropylene Insulation for HVDC Cables 292 Space Charge and Dielectric Breakdown 312.1 Introduction 312.2 Effect of Elastomer on Space Charge and Breakdown Characteristics 322.3 Effect of Inorganic Nanofiller on Space Charge and Dielectric Breakdown 452.3.1 Metal Oxide Nanoparticles 452.3.2 Nanoplatelets 522.4 Effect of Organic Compounds on Space Charge and Dielectric Breakdown 642.4.1 Introduction 642.4.2 Voltage Stabilizer 642.4.3 Antioxidant Additives 802.5 Conclusion and Outlook 92References 923 Electrical Treeing Phenomenon 1033.1 Introduction 1033.2 Electrical Treeing Under Impulse Superimposed on DC Voltage 1053.2.1 Effects of Impulse Amplitude 1063.2.2 Effects of Impulse Frequency 1113.2.3 Effects of DC Voltage Amplitude 1123.3 Effect of Ambient Temperature on Electrical Treeing 1203.3.1 Effect of Low Temperature 1203.3.2 Effect of Operating Temperature 1293.4 Effect of Bending Deformation on Electrical Treeing 1413.4.1 Effect of Bending Deformation 1413.4.2 Effect of Elastic Phase 1483.5 Methods for Suppressing Electrical Treeing 1543.5.1 Effect of the Type of Voltage Stabilizer 1573.5.2 Effect of the Content of Voltage Stabilizer 1603.6 Conclusion and Outlook 165References 1664 Insulation Thickness Optimization for HVDC Cables 1734.1 Introduction 1734.1.1 Development of Insulation Thickness of HVDC Cables 1734.1.2 Advantages of Insulation Thinning 1744.2 Electric Field Distribution Calculation Model for HVDC Cables 1744.2.1 Classical Electromagnetic Theoretical Model 1744.2.2 Bipolar Electronic–Ionic Charge Transport Model 1784.2.2.1 Charge Generation 1794.2.2.2 Charge Transport 1794.2.2.3 Charge Recombination 1824.2.2.4 Charge Extraction 1824.3 Space Charge and Electric Field Under DC Voltage 1824.4 Space Charge and Electric Field Under Polarity Reversal Voltage 1874.4.1 Effect of Temperature Gradients 1884.4.2 Effect of Polarity Reversal Periods 1944.5 Insulation Thickness Optimization for HVDC Cables 1984.5.1 Theoretical Design and Verification of Insulation Thickness of dc Cable 1984.5.1.1 Design Method of Insulation Thickness of HVDC Cables 1994.5.1.2 Analysis and Calculation of Insulation Thickness of HVDC Cables 2004.5.1.3 Verification of Insulation Thickness of DC Cable 2034.5.2 Insulation Thickness Optimization Based on Modified BEICT Model 2074.6 Conclusions 214References 214Part II Polypropylene Insulation for HVAC Cables 2195 Polarization and Dielectric Relaxation 2215.1 Introduction 2215.2 Effect of Blending Modification 2255.2.1 FDS of PP Blend Insulation 2255.2.2 Effect on Dipole Orientational Polarization 2285.2.3 Effect on Carrier Hopping Polarization 2305.3 Effect of Monomer Grafting 2335.3.1 FDS of Grafting PP Insulation 2385.3.2 Effect on Dipole Orientational Polarization 2405.3.3 Effect on Carrier Hopping Polarization 2425.4 Effect of Thermal Ageing 2455.4.1 FDS of Thermal-Aged PP Insulation 2455.4.2 Effect on Dipole Orientational Polarization 2475.4.3 Effect on Carrier Hopping Polarization 2495.5 Conclusion and Outlook 252References 2526 AC Electrical Treeing and Dielectric Breakdown 2576.1 Introduction 2576.2 Electrical Treeing Dependent on Crystalline Morphology 2606.2.1 Crystalline Morphology 2606.2.2 Effect on Electrical Tree 2636.2.3 Effect on AC Breakdown 2696.3 An Insight into Electrical Tree Growth Within Heterogeneous Crystalline Structure 2736.3.1 Mechanism of Heterogeneous Crystalline Structure 2736.3.2 Heterogeneous Crystalline Structure Modulation Enhancing Dielectric Strength 2816.3.3 Electric Field Simulation of Heterogeneous Crystalline Structure 2916.3.3.1 Heterogeneous Mesoscopic Structure Simulation 2916.3.3.2 Electric Field Simulation in Mesoscopic Structure 2946.4 Methods for Suppressing Electrical Treeing 2976.4.1 Effect of Nucleating Agent and Cooling Rate on Dielectric Property of PP/POE 2976.4.2 Enhanced Dielectric Breakdown Property of Polypropylene Based on Mesoscopic Structure Modulation by Crystal Phase Transformation 3106.5 Conclusions 325References 3277 Electrothermal Aging and Lifetime Modeling 3337.1 Introduction 3337.2 Aging Mechanism and Lifetime Models 3347.2.1 Physical Lifetime Models 3347.2.1.1 Thermodynamic Models 3357.2.1.2 Space-Charge-Based Models 3387.2.1.3 PD-Induced Damage Model 3417.2.2 Phenomenological Lifetime Models 3437.2.2.1 Accelerated Life Tests Under Constant Stress 3437.2.2.2 Accelerated Life Tests Under Step Stress 3447.2.2.3 Single-Stress Electrical Lifetime Models 3457.2.2.4 Single-Stress Thermal Lifetime Models 3477.2.2.5 Combined Electrothermal Lifetime Models 3497.3 Thermal Aging 3527.3.1 Effect on Physical–Chemical Properties 3527.3.1.1 FT-IR Test 3527.3.1.2 XRD Test 3537.3.1.3 DSC Test 3547.3.1.4 SEM Test 3557.3.2 Effect on Mechanical and Electrical Properties 3557.3.2.1 Mechanical Test 3557.3.2.2 Conductivity Test 3577.3.2.3 FDS Test 3587.3.2.4 AC Breakdown Test 3597.3.3 Lifetime Prediction Under Thermal Stress 3607.3.3.1 Lifetime prediction model 3607.3.3.2 Validation of Prediction Model 3627.4 Electrical–Thermal Aging 3637.4.1 Breakdown Under Electrical–Thermal Stress 3637.4.2 Lifetime Models and Prediction 3677.5 Conclusions 370References 371Index 375