D. Johari

Universiti Teknologi MARA | UiTM · School of Electrical Engineering

This paper presents the characteristics of the preliminary breakdown pulses (PBP) in 51 positive ground flashes recorded during 2014 summer thunderstorms in Sweden. Electric field measurements were conducted remotely using a broadband antenna system (up to 100 MHz) for a recording length of 1 s with 200 ms trigger time. In the analysis, PBP trains...

This paper presents the characteristics of the electric field pulses observed during leader propagation in positive ground flashes. We analysed in detail the electric field changes occurring just before the first return stroke in 51 positive ground flashes during 2014 summer thunderstorms in Uppsala, Sweden. Pronounced leader pulses (having the sam...

This paper presents the characteristics of the electric fields produced by the first and the subsequent return strokes observed in positive ground flashes in Sweden. Fifty one positive ground flashes containing 60 return strokes recorded during 2014 summer thunderstorms were analyzed. In our analysis, only 12% of the cases were multiple-stroke whil...

This paper presents the development of hybrid Meta-Evolutionary Programming (EP) and Artificial Neural Network (ANN) prediction system for lightning occurrence based on historical lightning and meteorological data from a Malaysian environment. It involved the development of the ANN design and embedding EP optimization technique for optimizing learn...

Malaysia has high lightning and thunderstorm occurrences throughout the year. A vast amount of its data have been recorded which allows various lightning-related studies to be conducted. This paper presents the application of artificial neural network (ANN) in predicting the occurrence of lightning events based on historical lightning and meteorolo...

Economic dispatch study is important in the electric power industry because it is concerned with efficient electrical power production and economics. It is crucial to reduce the operating costs of electric energy because even small savings have a large impact on total generation costs and fuel consumption. This paper presents the proposed algorithm...

span>Particle swarm optimization (PSO) is the most widely used soft computing algorithm in photovoltaic systems to address partial shading conditions (PSC). The success of the PSO run heavily depends on the initial population size (NP). A higher NP increases the probability of a global peak (GP) solution, but at the expense of a longer convergence...

Over the years, many studies have been conducted to measure, analyze, and characterize the lightning electric field waveform for a better conception of the lightning phenomenon. Moreover, the characterization mainly on the negative return strokes also significantly contributed to the development of the lightning detection system. Those studies most...

Lightning is a naturally occurring phenomenon that involves a sudden electrostatic discharge caused by an imbalance between electrically charged cloud regions. Although lightning is visibly amazing, its impact can be dangerous and damaging, which many studies have carried out lightning-generated electric field measurements to assess the electrical...

Lightning can occur between the clouds (intra-clouds), ground-to-cloud (CG), and inside the clouds. The lightning strike hazards can be managed appropriately using a lightning detector system consisting of an antenna, buffer amplifier circuit, and a measurement device. In this study, the development and fabrication of small-scale parallel plate ant...

Over the years, many studies have been conducted to measure and classify the lightning-generated electric field waveform for a better understanding of the lightning physics phenomenon. Through measurement and classification, the features of the negative lightning return strokes can be accessed and analysed. In most studies, the classification of ne...

Compared to negative cloud-to-ground (CG) lightning, positive CG are less frequent but can produce strokes with higher peak currents making them to be potentially more dangerous. This paper presents an investigation on positive cloud-to-ground (CG) lightning activity in Shah Alam, Malaysia recorded by SAFIR 3000 lightning location system (LLS). For...

span>The initialization stage12 of a Soft Computing (SC) algorithm is vital as it affects the success rate of algorithms in solving multi-peak global optimization problems. The individuals in an initial population, which are known as search agents, are often generated randomly using pseudo-random number generator (PRNG) due to unavailability of pri...

span>This paper presents the conceptual study on grid-to-electric vehicle (G2V) wireless power transfer (WPT) using Single Phase Matrix Converter (SPMC). In this work, the SPMC is used as a direct AC to AC converter to convert the input supply voltage at 50 Hz frequency to the output of 20 kHz to meet the WPT switching frequency operation of the tr...

span>The development of active power filter (APF) using rectifier boost technique has been identified to compensate for the pulsating nature of the distorted supply current waveform of non-linear load. In this work, investigation is carried out on the operation of rectifier without any filters function. This is then extended to operate the rectifie...

This paper presents the analysis study between multilevel inverters that are often classified into multilevel voltage source and multilevel current source inverters. For multilevel voltage source inverter (MVSI), the specific topology studied for this work is the Cascaded H-Bridge MVSI. Whereas, the multilevel current source inverter (MCSI) is base...

The main components of a Stand-Alone Photovoltaic (SAPV) system consists of PV array, DC-DC converter, load and the maximum power point tracking (MPPT) control algorithm. MPPT algorithm was used for extracting maximum available power from PV module under a particular environmental condition by controlling the duty ratio of DC-DC converter. Based on...

span>The main components of a Stand-Alone Photovoltaic (SAPV) system consists of PV array, DC-DC converter, load and the maximum power point tracking (MPPT) control algorithm. MPPT algorithm was used for extracting maximum available power from PV module under a particular environmental condition by controlling the duty ratio of DC-DC converter. Bas...

Drastic climate change and more frequent occurrences of natural disaster which destruct power system infrastructure results i n power delivery congestion at the transmission network. Heavily loaded transmission network that operates during adverse weather is very prone to outage, hence may trigger more critical problem such as voltage collapse. Res...

In this study, electromagnetic field radiation bursts known as chaotic pulse trains (CPTs) and regular pulse trains (RPTs) generated by lightning flashes were analyzed. Through a numerical analysis it was found that a typical CPT could be generated by superimposing several RPTs onto each other. It is suggested that the chaotic pulse trains are crea...

In this study, the electric field signatures of negative ground flashes pertinent to the Swedish thunderstorms were recorded simultaneously during the summer of 2014 using wide (up to 100 MHz) and narrow (at 3 MHz and 30 MHz as central frequencies) bandwidth antenna systems. The electric field signatures were recorded for a time duration of 250 ms....

Compared to negative ground flashes, not much is known about the characteristics of leaders in positive ground flashes. This paper presents some characteristics of the electric field pulses observed during leader propagation in positive ground flashes. We analyzed in detail the electric field changes produced by 50 positive ground flashes during 20...

Power transformer has been identified as crucial and vital equipment in power system. Any disturbance such as faults will result in immense impact to the whole power system. This paper presents the development of an Evolutionary Programming (EP) – Taguchi Method (TM) – Artificial Neural Network (ANN) based technique for the classification of incipi...

— In this study, Electric field sensed by the wide band and narrow band (3MHz and 30MHz) antenna systems recorded simultaneously, have been analysed. The measurement was carried out during the summer 2014. Although, the electric field produced by lightning was recorded for 250ms, field radiation by the preliminary breakdown (PB) process has only be...

In this paper, we report for the first time the observation of chaotic pulse train (CPT) preceding natural subsequent negative return strokes and also CPT occurrence in IC flashes from tropical thunderstorms in South Malaysia. In CG flashes, all CPTs were occurred in between return strokes with 41.1% have occurred between the first and second retur...

This paper presents optimized Artificial Neural Network to identify and detect incipient faults in power transformer. This study involved the development of Artificial Neural Network (ANN) models and embedding Evolutionary Programming (EP) as the computational technique to optimize the built ANN. The optimized ANN is namely as EPANN. As one of the...

This paper presents hybrid Taguchi-Artificial Neural Network to detect incipient faults in oil-immersed power transformer. It involved the development of Artificial Neural Network (ANN) designs and embedding Taguchi methodology to fine tune the parameters of a backpropagation feed-forward ANN. Detection of incipient faults in power transformer is e...

Power transformer is one of the fundamental equipments in the power system. Transformer breakdown or damage may interrupt power distribution and transmission operation, as well as incur high repair cost. Thus, detection of incipient faults in power transformer is essential and it has become an interesting topic to study. This paper presents the app...

Thunderstorm is a form of weather characteristic containing strong wind, lightning, heavy rain and sometimes snow or hail. It can be associated with a cloud type of cumulonimbus. Depending on its type, thunderstorm has great potential to produce serious damage to human life and property. Therefore, there are many sophisticated instrument used to re...

Total system losses of the power system relate to the reactive power management in the network. This paper presents a method to minimize the system losses by utilizing Reactive Power Planning (RPP) approach. In this technique, the control variables of RPP were formulated as an optimization problem and Multiagent Immune Evolutionary Programming (MAI...

An electrical power system consists of many individual dynamic devices connected together to form a large and complex dynamic system. To analyze the behavior of such devices, its physical model needs to be transformed into mathematical model before it can be solved on a computer. In electric utility practices, the aspect of modeling and computation...

An essential element of electric utility resource planning is the long term forecast of the electricity consumption. This paper presents an approach to forecast annual electricity consumption by using artificial neural network based on historical data for Malaysia. It involves developing several ANN designs and selecting the best network that can p...

This paper describes the design of a fuzzy logic controller using voltage output as feedback for significantly improving the dynamic performance of boost dc-dc converter by using MATLAB@Simulink software. The objective of this proposed methodology is to develop fuzzy logic controller on control boost dc-dc converter using MATLAB@Simulink software....

This paper presents the development of hybrid Meta-Evolutionary Programming and Artificial Neural Network lightning prediction system based on historical lightning and meteorological data in Malaysia. It involved the development of the ANN design and optimization of the system using EP optimization technique. ANN is employed as it has the ability t...

The main objective of this document is to compare the performance between Fuzzy Logic controller (FLC) and Proportional Integral Derivative controller (PIDC) in improving the performance of DC/DC Buck Converters. The evaluation of the output has been carried out and compared by software simulation using MATLAB Simulink. Fuzzy logic controller has b...

This paper presents a new technique termed as Multiagent Immune Evolutionary Programming (MAIEP) optimization technique for optimizing reactive power planning with an objective to improve the loadability margin in a power system. Loadability margin is an issue in power system operation due to the increase in system loading with limited avenues for...

Assessment of power transformer conditions has become increasingly important in recent years. As an asset that represents one of the largest investments in a utility's system, detection of incipient faults in power transformers is crucial. Dissolved gas-in-oil analysis (DGA) is a successful technique to detect these potential faults and it provides...