Lightning insulation coordination is based on statistical approaches. This allows to correlate the electrical stress caused by lightning and the electrical strength of the insulations, both having probabilistic nature. This chapter provides an example of lightning insulation coordination. Specifically, it deals with the statistical appraisal of the so-called lightning performance of distribution systems, carried out by means of Monte Carlo (MC) simulations. The relevant application to both the cases of direct and indirect lightning events, considering the correlation between the probability distributions of the lightning current parameters, is described and discussed. In particular, the application to the indirect events is based on the definition of a surface around the power line and on the calculation of the induced voltages along the line caused by indirect events having stroke location uniformly distributed within such a surface. The result obtained through the MC simulations is fmally scaled taking into account the annual number of fl ashes per square kilometer expected in the region of interest. In order to obtain significant results, two aspects need to be considered: the surface around the power line should be large enough in order to collect all the events that may endanger the insulation, and the density of the stroke locations should be sufficiently high. Therefore, for medium voltage systems, or even more for the case of low voltage ones, the area can reach a large value indeed, and the number of events to be considered can be consequently huge. The chapter also describes the application of the stratified sampling technique able to reduce the computation effort typical to this type of calculation.

This chapter organises the lightning interactions with power transmission lines from the simple consequences of a direct stroke attachment to an unshielded line, to the complex consequences of a stroke attachment to shielded line with multiple groundwires, including the UBGW effects from phases with TLSA protection. It builds on the information in Chapters 1 and 2 of this volume to develop important measures in transmission line lightning performance: N L , the number of fl ashes (100 km) -1 year -1 of line length per year, and the number of those fl ashes that bypass an OHGW, giving a Shielding Failure Flashover Rate (SFFOR) with the same units. Simplified models from industrial standards are then used to illustrate important principles and concepts such as the 'critical current' that just causes backflashover from a normally earthed component to a phase conductor. Matrix methods are used to manage the self and mutual surge impedance, with sample calculations shown using Microsoft Excel Tm as a common language. Specialised computer programs to calculate BFR on lines with OHGW and full or partial application of TLSA are described further in Chapter 12 of this volume.

In this chapter, the major mechanisms by which overvoltages are stemmed from lightning were discussed. Particular emphasis was given to the voltages nduced on overhead LV networks by nearby strokes and to those transferred from the MV system, which are the most important ones on account of their magnitudes and frequencies of occurrence. Simple and effective models were used to represent the high frequency behaviour of typical distribution transformers and LV power installations

In this chapter, a broad view of 'lightning protection' includes the use of lightning in all proactive protection strategies. A summary of measurement technologies used on electric power systems and achievements of research campaigns will show the origins of some traditional surge waveforms, such as the 1.2/50 standard lightning impulse voltage wave, from nearly 100 years ago. Some of these methods and many results still apply to present-day Smart Grid component protection. The authors also cover the sequential evolution of the following: traditional travelling wave systems (TWS) for finding faults along individual cables and lines, from 1940s; the modern LLS based on travelling waves in two dimensions, from 1980s; and the recent wide-area power system monitoring and measurement systems, using time-synchronized measurements of voltage and current phasors (synchrophasors) from 2005, classed as a 'Smart Grid' initiative.

In this chapter, a general description of lightning overvoltage effects phenomena of renewable systems (with special focus on photovoltaic (PV) systems) is disclosed. A brief introduction to solar radiation and PV systems is presented in order to set up the general parameters and terminology of PV systems and their components. Time-dependent parameters, such as position of the sun, Earth's rotation, and solar's and tilted surface's (such as PV systems) angles, do form the basic references used in PV systems and in this chapter. Different literature sources were consulted for the representation of the available models for the estimation of the global solar radiation on the tilted surface or PV systems.

Electromagnetic computation methods (ECMs) have been widely used in analyzing lightning electromagnetic pulses (LEMPs) and lightning-caused surges in various systems. One of the advantages of ECMs, in comparison with circuit simulation methods, is that they allow a self-consistent, full-wave solution for both the transient current distribution in a three-dimensional conductor system and resultant electromagnetic fields, although they are computationally expensive. Among ECMs, the finite-difference time-domain (FDTD) method has been the most frequently used in lightning electromagnetic field and surge simulations. In this chapter, applications of the FDTD method to lightning electromagnetic field and surge simulations are reviewed. The applications include (i) surges on grounding electrodes, (ii) lightning surges on overhead power transmission lines (TLs) and towers, (iii) lightning surges on overhead power distribution and telecommunication lines, (iv) lightning electromagnetic environment and surges in power substations, (v) lightning surges on underground power and telecommunication cables, (vi) lightning surges in wind-turbine-generator towers, (vii) lightning surges in photovoltaic (PV) arrays, (viii) lightning surges and electromagnetic environment in buildings, (ix) lightning electromagnetic fields at close and far distances, and others.