Electrical Safety Engineering of Renewable Energy Systems

RODOLFO ARANEO, PhD, is an Associate Professor at the Department of Electrical Engineering at the University of Rome "La Sapienza".MASSIMO MITOLO, PhD, is a Professor of Physics and Electrical Engineering at the School of Integrated Design, Engineering and Automation of the Irvine Valley College, Irvine California.

• Preface ixAcknowledgments xi1 Fundamental Concepts of Electrical Safety Engineering 11.1 Introduction 11.2 Electric Shock 21.2.1 Ventricular Fibrillation 31.2.2 The Heart-current Factor 51.3 The Electrical Impedance of the Human Body 61.3.1 The Internal Resistance of the Human Body 71.4 Thermal Shock 101.5 Heated Surfaces of Electrical Equipment and Contact Burn Injuries 121.6 Ground-Potential and Ground-Resistance 141.6.1 Area of Influence of a Ground-electrode 181.7 Hemispherical Electrodes in Parallel 181.8 Hemispherical Electrodes in Series 191.9 Person’s Body Resistance-to-ground and Touch Voltages 201.10 Identification of Extraneous-Conductive-Parts 241.11 Measuring Touch Voltages 262 Safety-by-Design Approach in AC/DC Systems 312.1 Introduction 312.2 Class I PV Equipment 332.3 Class II PV Equipment 352.4 Ground Faults and Ground Fault Protection 352.5 Functionally Grounded PV Systems 372.6 Non-Ground-Referenced PV Systems 402.7 Ground-Referenced PV Systems 422.8 Fire Hazard in Ground-Referenced PV Systems 442.9 Faults at Loads Downstream the PV Inverter in Ground-Referenced PV Systems 472.10 Non-Electrically Separated PV System 482.11 PV Systems Wiring Methods and Safety 502.12 d.c. Currents and Safety 522.13 Electrical Safety of PV Systems 552.14 Rapid-Shutdown of PV Arrays on Buildings 572.15 Hazard and Risk 583 Grounding and Bonding 633.1 Introduction 633.2 Basic Concepts of Grounding Systems: The Ground Rod 673.3 The Maxwell Method 773.4 Multiple Rods: Mutual Resistance 833.5 Ground Rings and Ground Grid 873.6 Complex Arrangements: Rings and Ground Grids Combined with Rods and Horizontal Electrodes 1004 Lightning Protection Systems 1074.1 Review of Natural Lightning Physics, Modeling and Protection 1084.2 Lightning Protection of PV Systems 1214.2.1 Ground-Mounted PV Systems 1244.2.2 Rooftop Mounted PV Systems 1264.2.3 Protection against Overvoltage 1284.2.4 Surge Protective Devices (SPDs) 1304.3 Lighting Protection of Wind Turbines 1364.3.1 Lightning Protection System (LPS) 1394.3.2 Step and Touch Voltages 1434.3.3 Lightning Exposure Assessment 1444.3.4 Assessment of the Average Annual Number of Dangerous Events NL Due to Flashes Directly to and near Service Cables 1474.3.5 Lightning Protection Zones 1494.4 High-Frequency Grounding Systems 1514.4.1 Arrangement of Ground Electrodes 1554.4.2 Effective Length of a Ground Electrode 1574.4.3 Frequency-dependent Soil and Ionization 1585 Renewable Energy System Protection and Coordination 1695.1 Introduction 1695.2 Power Collection Systems 1705.3 Cable Connections 1825.4 Offshore Wind Farm 1885.5 Distributed Energy Resources: Battery Energy Storage Systems and Electric Vehicles 1926 Soil Resistivity Measurements and Ground Resistance 2056.1 Soil Resistivity Measurements 2056.2 Wenner Method 2086.3 Schlumberger Method 2146.4 Multi-layer Soils 2146.4.1 Ground Grid in Multi-layer Soil 2176.4.2 Ground Rod in Multi-layer Soil 2196.5 Fall-of-Potential Method for Ground Resistance Measurement 2206.6 Slope Method for Grounding Resistance Measurement 2236.7 Star-delta Method for Grounding Resistance Measurement 2246.8 Four Potential Method for Grounding Resistance Measurement 2256.9 Potentiometer Method for Grounding Resistance Measurement 226Appendix 1: Performance of Grounding Systems in Transient Conditions 2311 Grounding System Analysis 2322 Mathematical Model 2333 Computation of Impedances 2354 Green’s Function 2374.1 Static Formulation 2374.1.1 One-Layer Ground 2424.1.2 Two-Layer Ground 2434.2 Dynamic Formulation 2454.2.1 Equivalent Transmission Line Approach 2495 Numerical Integration Aspects 2525.1 Singular Term 2525.2 Sommerfeld Integrals 254Appendix 2: Cable Failures in Renewable Energy Systems 2651 Cable Failures in Renewable Energy Systems: Introduction 2662 Possible Solutions 2672.1 Optimal Solutions 2682.2 Termite Attacks Prevention 2693 Non-destructive Methods for Cable Testing and Fault-locating 2693.1 Insulation Resistance (IR) Test 2713.1.1 IR Measurement of the Cable Insulation (XLPE) 2713.1.2 IR Measurement of the Polyethylene (PE) Cable Jacket 2723.2 High-Potential Test 2723.3 LCR Test 2733.3.1 Insulation Resistance (IR) 2733.3.2 Dielectric Absorption Ratio (DAR) 2733.3.3 Polarization Index (PI) 2743.3.4 Quality Factor (Q) 2743.3.5 Dissipation Factor (DF) 2743.3.6 Time Domain Reflectometry (TDR) Test 2753.3.7 Arc Reflection (ARC) Test 2763.3.8 Bridge Methods 2763.4 Cable Fault Analysis 2793.4.1 Prelocation 2793.4.2 Pinpointing 2804 Sheath and Jacket Repairs 2805 Termite Baiting Stations and Monitoring 2816 Termite-proof Cables 283Index 285