Lightning severity in Malaysia and some parameters of interest for engineering applications

To the electric utility engineer, the parameters of the flash that are of primary interest are the crest current for the first and subsequent strokes, the waveshape of these currents, correlation between the parameters, the number of strokes per flash and flash incidence rates where the ground flash density, denoted as flashes per square km-year and symbolized by Ng. The first three parameters, as we know them today, are to a very large extent based on the measurements of Berger. Berger's masts, 70 and 80 meters high, were mounted atop Mt. San Salvatore (Switzerland), which is 650 meters above Lake Lugano, where it can be readily noted that these 125 records represent one of the best and most extensive set of data available to the industry to date. This paper focuses on the lightning severity scenario in Malaysia, which could also applicable to other tropic countries, and some of the useful parameters for lightning protection system design and forensic study. Some specific engineering applications have also been summarised, taking into account various lightning parameters, available from past and current measurements

A review on factors for maximizing solar fraction under wet climate environment in Malaysia

Solar energy is the most promising source of clean, renewable energy and it has the greatest potential of any power source to solve the world's energy problems. However, the problem, is how best to harness this vast amount of solar energy. Nevertheless, even if highly efficient Concentrating Solar Power (CSP) could be made cheaply, there would be considerable change in solar power. This technology is expected to be more efficient and to achieve a manufacturing cost of less than $1/W near future. This paper reviews and elaborates the methodology utilized to design and fabricate the solar dish concentrator and outlines the parameters that can be used to increase the efficiency of solar fraction in parabolic dish concentrator under wet climate environment in Malaysia. The study finally provides ideas to the continually increasing ability of these technologies to concentrate and harness solar energy for electricity production and thus eliminate the growing concern over climate change and how it will hurt the region's environment, human health and economy

Application of the insulator coordination gap models and effect of line design to backflashover studies

Any insulation coordination study must accurately (or as accurately as possible) express the type and magnitude of all overvoltages on the power system. If these overvoltages are higher than the rating of the equipment, they will result in damage to that equipment. This paper presents the application of the insulator coordination gap models and the effect of line design to the line performance in terms of backflashover rate. The models which are ranging from as simple as voltage controlled switch to as detail as leader progression model will carefully be evaluated. Sensitivity analyses on the effect of line designs such as variation in footing resistance, height of tower/conductor, tower surge impedance and soil resistivity will also be carried out in determining the backflashover rate and the probability of transformer damage by comparing the maximum voltage recorded at the substation entrance with the basic lightning insulation level (BIL). Results will then be compared in finding which model makes the analysis more or less sensitive to any design parameter

Protection of naval systems against electromagnetic effects due to lightning

This study investigates possible lightning threats to naval crafts, especially those sailing in the shallow waters of tropical oceans where thunderstorms prevail throughout the year and Far-East Asian region where dangerous positive lightning is a significant characteristic in winter thunderstorms. It is empathized that sea water acts as nearly a perfect conductor thus lightning electromagnetic transients propagate over the sea with almost zero attenuation of amplitude and high frequency components intact. The ratio between the peak electric fields at 5 km from the lightning channel, after fields propagate over dry soil and over sea water is 0.75. The ratio between the peak electric field derivatives under the same conditions is 0.1. Such small ratios are observed in the magnetic fields and their time derivatives as well. Apart from the conductivity, the topological irregularities of the plane over which propagation takes place also contribute to further attenuation of fields and their time derivatives. This makes marine naval systems more vulnerable to lightning induced effects than their ground-based counterparts. The paper discusses in detail the lapses of existing naval standards in the defense of electrical and electronic systems against both direct lightning currents and induced effects of nearby lightning. Consequently we propose the development of a dedicated standard for the lightning protection of naval systems, with the inclusion of several significant recommendations specified in this paper

Considering on return stroke current wave shape for tall objective cases

The return stroke current along the lightning channel for striking of the lightning to tall objective case is different from ground surface case with many factors affect this phenomenon. This study considers the engineering related to return stroke current models where the general equations are expressed and different models are generated. The results obtained will be compared and discussed

New algorithm for evaluation of electric fields due to indirect lightning strike

Evaluation of electric field due to indirect lightning strike is an interesting subject. Calculation of electric and magnetic fields in time domain with the consideration of ground conductivity effect in the shortest possible time is an important objective. In this paper, using dipole method, Maxwell's equation and Cooray-Rubinstein formula, a new method for calculation of electric field in time domain is proposed. In addition, this proposed algorithm can also be used to evaluate the effect at the far distance cases of observation point from lightning channel

Lightning protection: getting it wrong

Lightning has become a significant threat to electronics in many countries where the natural phenomenon has previously been treated only as an occasional attacker of careless living beings. Most tropical countries, several southern states of the U.S.A., Japan, and several parts of Australia, experience heavy annual lightning occurrence density. These regions also record high levels of lightning related injuries and accidents. However, many European countries, far northern and southern sections of North and South America, and countries such as South Africa and New Zealand areas that had not previously paid much attention to lightning (except South Africa where lightning research started in the early 20th century) are now more vigilant due to increased industrial development, greater sophistication of electronics, and wide expansion of power and communication networks. The extensive dependence of society on automated systems makes countries increasingly vulnerable to lightning related hazards. We present here information that we have obtained in several countries with respect to lightning protection through our long term experience in operating in the Asian region as researchers, consultants, and advisors on this subject. Our findings are directly applicable and will be helpful to many other regions of the world

Static power system security assessment via artificial neural network.

Maintaining system security is an important factor in the operation of a power system. The aim of this study is to evaluate the reliability using artificial neural network (ANN) in static security assessment to determine the security status of a power system. Feed Forward Back Propagation Neural Network is implemented to classify the security condition of IEEE 9 bus system. The input data of ANN are derived from offline Newton Raphson load flow analysis. The result obtained from the ANN method is compared with the Newton Raphson load flow analysis in terms of accuracy to predict the security level of IEEE 9 bus system and the computational time required by each method. The average time required by Newton- Raphson load flow analysis to evaluate security level of IEEE 9 bus system is 0.0481 seconds while the average time required by neural network is 0.0119 seconds. The accuracy of 13 hidden neurons feed forward back propagation neural network to predict the security level of IEEE 9 bus system is 98.57%. In conclusion, ANN is found to be reliable to evaluate the security level of IEEE 9 bus system

A theoretical approach to estimate the annual lightning hazards on human beings

This study provides a detailed account of the stepwise development of an empirical equation to estimate the number of lightning casualties in a given region. The factors considered in the development of the formula are; lightning density, population density and urbanization of a given region. The unknown constants of the equation have been evaluated by applying state-wise lightning death records and information on lightning density distribution in USA. The death figure per year due to lightning calculated for Sri Lanka using the empirical equation developed is in good agreement with the same figure reported for the country by actual data collected. The paper also discusses the limitations of the empirical equations that have been developed to calculate lightning density once the isokeraunic level is provided as the input parameter

New approach in time domain for evaluation of electric and magnetic fields near the lightning channel

The electric and magnetic fields due to lightning channel can be estimated by many methods such as Finite Difference Time Domain (FDTD) and dipole methods. Estimation of electric fields in time domain by dipole method for a realistic return stroke current along the lightning channel is very complex. On the other hand, the FDTD is an appropriate method for a close distance problem but it consumes high memory for the computer to process the result. This paper presents the combination of the FDTD and dipole methods for evaluation the magnetic fields at any observation points with less difficulty and less memory consumption. In addition, the use of the FDTD method provides the ability to evaluate the fields for the case of non-perfect ground conductivity. Hence, by applying the dipole and FDTD methods with the Caligaris et.al's algorithm, extended from Cooray-Rubinstein formula, the approach and formulation of electric and magnetic fields in time domain is proposed, with the consideration of the non-perfect ground conductivity effect. Results obtained from this new approach are compared with the measurements data published in literatures