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Ferroresonance is a complex non-linear electrical phenomenon that can make thermal and dielectric problems to the electric power equipment. Ferroresonance causes overcurrents and overvoltages which is dangerous for electrical equipment. In this paper, ferroresonance investigation will be carried out for the 33kV/110V VT at PMU Kota Kemuning, Malaysia using ATP-EMTP simulation. Different preconditions of ferroresonance modes were simulated to ascertain possible ferroresonance conditions in reality compare with simulated values. The effect of changing the values of series capacitor is considered. The purpose of this series of simulations is to determine the range of the series capacitance value within which the ferroresonance is likely to occur.

Lightning locating system is very useful for the purpose of giving exact coordinates of lightning events. However, such a system is usually very large and expensive. This project attempts to provide instantaneous detection of lightning strike using the Time of Arrival (TOA) method of a single detection station (comprises of three antennas). It also models the whole detection system using suitable mathematical equations. The measurement system is based on the application of mathematical and geometrical formulas. Several parameters such as the distance from the radiation source to the station and the lightning path are significant in influencing the accuracy of the results (elevation and azimuth angles). The signals obtained by all antennas were analysed using the LabVIEW software. Improvements in the lightning discharge locating system can be made by adopting a multi-station technique instead of the currently adopted single-station technique.

This paper proposes a new model of soil ionization, in the form of an equivalent circuit containing capacitive and resistive elements representing a network of soil particles and air voids. In previously published models, the effect of soil ionization is only indirectly considered by changing the soil resistivity and the electrode radius. This has resulted in inferior performance of those models in terms of voltage response accuracy. In this work, the energy balance concept was applied to compute the arc resistance. The soil structure is modeled by using two-layer capacitor elements. The soil ionization process is incorporated inside the two-layer capacitor elements using specially derived differential equations. Unlike previous models, a discrete form of soil ionization is used. The accuracy of the proposed equivalent circuit model was confirmed by the small differences between the computed and experimental results.

The purpose of this research is to investigate the severity of voltages induced on gas pipeline installed in parallel to a 115 kV overhead transmission line. The overhead transmission line (OHTL) is configured as a single-circuit. One of the phases exposed to single phase to ground fault. Transmission of high voltage along the same right of way (ROW) with metallic conductor may possibly introduce interference on metallic conductors such as gas pipeline (GPL) due to power frequency voltage as well as due to phase faults and switching phenomena. Two main approaches were used to compute the induced voltages, namely the method of moment (MOM), which is based on electromagnetic field theory, and circuit based method. The simulation considers the length of OHTL and GPL are 30 km and 10km respectively. The pipeline buried at 1 m underground in homogenous earth structure with various soil resistivites ranged from 10 to 1000 Ω-m. The transmission line consists of 150 towers and 200 m span length. The separation distance between the GPL and OHTL is varied from 5 to 100 m. The phase to ground fault current changed from 0.5 to 10 kA. Several observation points are made throughout the corridor, to examinant the induced voltages at different locations. The result show that, the soil resistivity, separation distance, and fault current had significant effect on pipeline induced voltage. In case of the observation points lying on the soil or on the outer surface of the pipeline coating, the induced voltage increased, when the soil resistivity increase, as expected. In case of the observation points placed inside the pipeline metal, and the pipeline is well coated, the induced voltage will decreased, when the soil resistivity increase.

The effect of frequency dependent soil properties on the impedance and transient response of the grounding electrode was investigated. The frequency dependent soil models as proposed by Scott, Smith-Longmire, and Visacro-Alipio were critically reviewed. A novel method was proposed to integrate the frequency dependent soil electrical properties in the circuit model of grounding electrode. To validate the application of the method in circuit model, the voltage responses of the grounding electrode obtained by the circuit and electromagnetic models were compared. The voltage responses obtained by the circuit and electromagnetic models were in excellent agreement in terms of voltage peaks and wave shapes. The differences between voltage peaks obtained by the circuit and electromagnetic models were found less than 1%.

This aim of this paper is to study the preliminary breakdown pulses (PBP) of positive cloud-to-ground (+CG) lightning flashes in Malaysia. There is a difference in PBP characteristics when a comparison is made between positive and negative flashes. To the best of the authors’ knowledge, this is the first time the PBP characteristics preceding positive lightning in Malaysia are reported. This study was carried out in Johor Bahru, Malaysia using a broadband antenna system during a monsoon period (Oct-Dec, 2012). It is found that the PBP for +CG lightning is much more complicated compared to the positive cloud-to-ground (–CG) lightning since only negative PBP trains are usually present in the –CG lightning. Out of 21 analyzed positive flashes, four types of PBP trains were identified according to their initial polarities. These are negative PBP (20%), positive PBP (15%), PBP with polarity reversal (10%), and PBP with irregular polarity (15%). The balance 40% of flashes are without any PBP. The effect of geographical region may also cause the observed differences in the cloud discharge processes including the types of PBP. More studies are needed to determine the relationship between the return stroke and PBP.

The purpose of this paper is to investigate the severity of lightning induced voltages on a gas pipeline installed in parallel with overhead transmission line using two different simulation packages. The results from this study using CDEGS, which solves a given problem based on electromagnetic computations, reveal that the induced voltages on the pipeline are more accurate compared to that obtained by PSCAD simulation, which is based on the circuit approach. Unlike PSCAD, CDEGS considers many salient factors such as soil model, inductive, capacitive and conductive couplings, and multiple soil structures. Models of a double circuit 132kV transmission line, gas pipelines, soil with different resistivities and variable lightning surges were developed. The effects of pipelines located at various heights above ground and distance of pipeline from the power lines were also studied. Compared to previously published work using PSCAD, it is found that CDEGS has given more accurate results. Several findings which were not possible using PSCAD were observed such as the effect of soil structure on induced voltage and multiple layers soil. This also led to better understanding of the conductive coupling from lightning strikes and fault conditions. The modeling work using CDEGS not only useful for providing more reliable data for further protection and mitigation techniques, but is also very versatile to study the effects of various other important factors affecting the induced voltage on the pipelines.

This paper presents a study of the ferroresonance phenomena occurring on Voltage Transformer (VT) of 132 kV substation at PMU Kota, Malaysia. Ferroresonance is a complex non-linear electrical phenomenon that can make dielectric and thermal problems to the electric power device. It causes overcurrent and overvoltage that is harmful for electrical apparatuses. The analysis is made by The Alternative Transients Program (ATP) which is a version of Electromagnetic Transients Program (EMTP) simulation compare with experimental events. The impact of changing the values of shunt capacitor (C shunt ) has been considered. The purpose of these kinds of simulations is to determine the range of the shunt capacitance value within which the ferroresonance is likely to occur.

Various methods are used to locate cloud-to ground lightning flash. The accuracy of the methods depends on the number of sensor stations, station topology, mathematical model adopted for the analyses, and the type of measuring equipment. For a single station with the configuration of short baseline in a measuring system, the accuracy of analysis is mostly based on the chosen mathematical equations (and assumptions) which can be solved in either linear or nonlinear mode. This paper concentrates on the simulation of a lightning flash and its detection based on the Time of Arrival (TOA) method by utilizing four broadband antennas. The accuracy of the TOA method is also evaluated in this work. A Matlab based simulation of the measuring system is implemented to construct a randomly located lightning flash with its corresponding electromagnetic radiation. Then, suitable mathematical models used as measurement systems based on the 3-antenna TOA method to determine the azimuth and elevation angles, which in turn can be used for the calculation of flash coordinates in term of (X, Y, Z) with the help of the fourth antenna.

Various methods are used to locate cloud-to-ground lightning flash. The accuracy of the methods depends on the number of sensor stations, station topology, mathematical model adopted for the analyses, and type of measuring equipment. For a single station with the configuration of short baseline in a measuring system, the accuracy analysis is mostly based on the chosen mathematical equations (and all relative assumptions) which can be solved in either linear or nonlinear mode. This paper concentrates on the simulation of a lightning flash based on Time of Arrival (TOA) method by utilizing three broadband antennas. The accuracy of the TOA method is also evaluated in this work. A Mat lab based simulation of the measuring system is implemented to construct a randomly located lightning flash with its corresponding electromagnetic radiation. Then, suitable mathematical models used as measurement systems based on the TOA method to determine the azimuth and elevation angles.

Lightning Air Terminal (LAT) is normally a sharp-tipped rod that is used to intercept direct lightning strike to ground structures. However it was found that LAT sometimes does not function as it should be due to aging and prolonged exposure to the acidic rain. This paper presents on the studies to determine chemical compounds; Polyvinyl Acetate and Polyvinyl Alcohol that can be use to enhance LATs' capturing capability. The chemicals act as a ‘make-up’ that helps the LAT to resist the effect of acid rain while increasing its conductivity and lightning leaders capturing capability. These findings were based on laboratory experiments. Further research has to be done on actual site testing using rocket-triggered lightning or on-situ monitoring of LATs performance. However it was found that in an environment where acidity is at pH 4, Polyvinyl Acetate is best for the LATs' performance improvement.

Over voltages in power system may occur due to lightning, fault or switching operation. These overvoltages could reach dangerous amplitudes for power system apparatus. To protect the system electrical equipment and to guarantee an economic and reliable operation, surge arresters are applied in almost all types of electrical power network. Gapless zinc oxide (ZnO) surge arresters are widely used. The surge arresters are usually connected between the phase and ground terminals. They limit the voltage level in equipments such as transformers below the withstand voltage level.

Weibull distribution has been used widely by many researches around the world especially in the analysis of high voltage experimental data. Unfortunately, most of the experimental data analysis was not following the accurate statistical technique. Thus in this paper, a statistical study on the tree inception voltage of silicone rubber and epoxy resin is presented. The tree inception voltage of silicone rubber and epoxy resin was measured via camera-equipped online monitoring system. The leaf-like specimen was used as test sample. The experiment was performed based on IEC 1072:1991 “Methods of Test for Evaluating the Resistance of Insulating Materials against the Initiation of Electrical Trees”. The obtained results were analysed statistically by using fitting method. Anderson-Darling goodness-of-fit test was performed in order to obtain the best fitting distribution. Comparison exercise was made between the fitted distribution and Weibull distribution. Based on Anderson-Darling tests, the tree inception voltage of silicone rubber and epoxy resin was best fitted with Johnson SB distribution. Based on this fitted distribution, the value of tree inception voltage for silicone rubber and epoxy resin was calculated and equalled to 3.1529 kV and 4.6528 kV respectively. Thus, it was found that, the fitting method by means of Anderson-Darling goodness-of-fit test was successful to recognize the best fitted distribution for the value of tree inception voltage for silicone rubber and epoxy resin.

Partial discharge is the main cause of cable failures. It is the responsibility of the utility company to ensure continuous supply of electricity to its customers. Hence, partial discharge needs to be detected and identified before it leads to supply interruptions due to cable insulation failure. In this work, PD diagnostic was carried out using the oscillating wave test system (OWTS). The measurement results together with the cable history data were then used to determine an index known as the severity index which can correctly characterise the cable health. Tests were carried out on 20 underground cables in the Temerloh region. Both crosslinked polyethylene (XLPE) and paper insulated lead cable (PILC) types of cable insulation were studied. By using the severity index classification of cable diagnosis, the electric utility can enhance the reliability of its distribution system by carrying out appropriate repair actions, and hence can save cost and reduce the number of forced outages.

Lightning is the transfer of significant charge between two charged object, it can occur between cloud to cloud, cloud to air and cloud to ground. Lightning strikes can kill people, knock out radio communication, electrical power devices, and destroy houses, trees as well as animals. The lightning strike hazards may be properly managed by using a lightning detector system. The detection concepts can be based on Electromagnetic Field or Electric field. In this paper, the characteristics of the flat plate antenna in measuring the electric field has been reviewed and analysed. The experiment using parallel plate antenna has been setup to detect the E field during the thunderstorm days. The E- field data has been collected and used for data manipulation or others application.

Analysis of shielding failure is carried out to observe flashover of insulators parallel with phase conductors of a transmission line associated with a lightning strike on phase conductor. Peak current of different magnitude have been used to represent the multiple strokes lightning (MSL). This paper aims to simulate the worst case due to transmission shielding failure with three direct strikes to a line phase conductor of magnitudes 25 kA, 35kA, 50kA, 65 kA and 80kA per strike respectively. Insulators where flashover had occurred with respect to MSL were identified. Installation of an arrester on a phase insulator where a flashover has occurred proven to be useful mitigation technique thatch could prevent flashover of the insulator and also improves lighnting performance of the line.

The lightning strike hazards may be properly managed by using a lightning detector system. In this paper, a system to determine the lightning strike distance from the measuring point was developed and tested. The time-to-thunder method was used to determine the strike distance. The technique was implemented using two kinds of sensors, namely, a broadband antenna to detect the electric field, and a microphone to detect the acoustic signal produced when lightning strike to the ground. A simple procedure to find the strike distance (d) was explained. A broadband parallel plate antenna was used to detect the electric field signal. The acoustic signal was detected by a microphone. The arrival time-delay between both signals was used to calculate the strike distance. The LabVIEW 8.5 software was used as a data logger to calculate the distance and to save the data. The lightning distance data were recorded for duration from January 2010 until March 2010 using the developed system. The range of the lightning detection is up to 10 km in radius.

Lightning mapping or locating systems are based on several working principles such as the Time of Arrival (ToA) and the Directional Finder (DF). The country wide lightning locating system (LLS) owned by TNB Malaysia is able to determine the coordinate of the cloud-to-ground lightning strike within 500m accuracy. A new method is proposed to determine the coordinate of any cloud-to-ground lightning strike within a certain local region with a better accuracy. The localised LLS is based on the measurement of induced voltages due to lightning strikes in the vicinity of an existing overhead telephone lines. The localised lightning locating system (LLLS) is made up of three components: an overhead telephone line, a voltage surge measuring system, and a central processing station. The overhead telephone line was purposely constructed in such a way to simply form a Cartesian system suitable for lightning strike location mapping. The mapping of the lightning strike locations was successfully implemented using a Lab View based program. Simulated lightning as well as real lightning data were used in this study. The induced voltage waveforms were compared with other previously published data. The location calculations were compared with those obtained from the national LLS. Results show that the LLLS captures more lightning strikes during the period of the study.

The gapless zinc oxide surge arresters enable the utility personnel to measure the leakage current due to its gapless physical configuration. An arrester leakage current which comprises of capacitive and resistive components is such an important parameter to be analyzed because its third harmonic resistive component is known to be directly related to the ageing or the degradation of the zinc oxide arrester itself. Various methods can be applied to monitor the condition of the surge arresters both for in-field as well as inside a laboratory. The resistive component extraction method called the Modified Shifted Current Method (MSCM) is utilised in this work. A portable device consisting of a tablet computer is able to measure and store the leakage current data and therefore can be used for an in-situ arrester condition assessment. This paper describes the performance of the portable device when measurements of the arrester leakage current were conducted at the 132-kV transmission substations. The leakage current data were analyzed and summarized to indicate its performance in terms of the accuracy of assessments made on the arrester conditions in actual substation environment.

The partial discharges (PDpsilas) due to artificial void in the sample of polyvinyl chloride (PVC) sheet have been investigated in this work. PD may cause the degradation of insulating materials and affect the lifetime of high-voltage apparatuses. Therefore, it is important to understand the correlation between PD inception voltages under various voltage source conditions. An experimental work using sphere ball-plane electrode system and a 0.8 mm PVC sheet was carried out. PD experimental results, such as PD inception voltage and PD charge, as functions of the applied voltage magnitude were compared for various types of applied voltage sources. The experimental results showed that the PD inception voltage under AC and DC voltage sources were not similar. The PD inception voltage under DC voltage source is lower than that for the AC voltage source. The results also show that the PD charges tend to increase when the voltage magnitude is increased.

Many studies have been conducted to monitor the degradation of MO arresters. The arresterpsilas leakage current, in particular, the third harmonic component of the resistive leakage current, is known to be directly related to the degree of degradation of the MO arrester. In order to extract the resistive component from the total leakage current, the voltage across the arrester terminals is usually measured as well. Although the measurement of total leakage current in substations or other installations can be easily done by using current shunts or current transformers, the measurement of voltage is relatively difficult if not prohibitive. Apart from the difficult and risky high voltage access for the voltage probe, the voltage measurement in a single phase may suffer from interference from nearby phases resulting in an unclean voltage reference. This paper introduces a new method to extract the resistive current from the total leakage current without the need of the voltage signal. It is referred to as the Modified Shifted Current Method (MSCM). The new modified shifted current method of extracting resistive current component from the metal-oxide surge arrester leakage total current is shown to work well based on the simulated as well as experimental results. The new technique compares very well with the conventional compensation technique, especially for resistive dominated leakage current waveforms. The new technique promises a simplified metal-oxide surge arrester monitoring of resistive leakage current since no additional high voltage transducer, as in commercially available devices, is needed. The consequential benefits are reduced cost and safer working procedure for the maintenance staff.

The status of insulation in electrical power equipment at any given point in time can be assessed by monitoring several properties which are sensitive to the amount of ageing. This procedure is commonly known as the diagnostic or non-destructive testing. For power transformers, the condition of the paper insulation can be assessed by an examination of the tracks provided by by-products of chemical dissociation of cellulose in solution with oil. This work addresses the need of paper insulation condition monitoring by determining the furfural contents in transformer oil using High Performance Liquid Chromatography (HPLC) technique. The degradation of electrical Kraft paper under laboratory ageing experiment was examined by means of assessing the increase of concentration of furan compounds as well as the increase of moisture content. Experimental results show that the thermal ageing process causes a proportional increase in 2-FAL furan compound as well as in moisture content. Both increases were shown to be related to the ageing or degradation of paper insulation.

The breakdown characteristics of various gaps are measured with and without a surge arrester in the circuit. Changes in the spark gap breakdown characteristics were observed when tested with the arrester in parallel and when subjected to various impulse shapes. A circuit model for the configuration is derived from these experimental results. Analysis of a proposed model for the voltage-time characteristics of the spark gap is presented. Simulation of the circuit model was conducted using EMTP, and showed agreement with the test data.

High-voltage surge arresters for high-current, high-energy duty often comprise several parallel ZnO columns. The extreme nonlinearity of the voltage-current characteristics of these columns demands close matching. However, even initially well matched columns can be unbalanced by ageing, partial discharges, self inductance and thermal effects. Two test techniques are described to examine current disparity in a pair of parallel 15 kV rated surge arresters: these are a current-ratio method and a current-difference method. The tests allow three aspects of parallel operation to be investigated: the use of ballast resistors to minimise mismatch effects and to increase energy absorption rating; the influence of the arrester layout on current parity; and temperature-difference perturbation of transient characteristics.

Zinc-oxide (ZnO) surge arresters are now well established as a very efficient and reliable form of overvoltage protection against both fast surges, such as those generated by lightning and gas-insulated switchgear, and high-energy surges generated by switching operations and temporary faults on the network. The addition of ZnO surge arresters to existing protection schemes reinforces the system's reliability and the security of supply. The protection characteristics of the parallel configuration formed by arresters and existing spark gaps at distribution voltages are studied. Tests on various spark-gap geometries, with and without surge arresters in parallel, have been carried out to determine breakdown characteristics, probability curves and voltage–time characteristics for different impulse shapes. It is found that the introduction of the arrester in the circuit modifies the prospective impulse which results in the shift of the breakdown characteristics towards higher voltages. A proposed circuit model, based on laboratory test data, is used to simulate such parallel configurations. Good agreement between test and simulated results is obtained. As a result of these tests, it is recommended that gap-sparkover characteristics based on short-tail (about 5µs) impulses are used for insulation co-ordination. The role of parallel airgaps in preserving the arrester energy-rating limits is also discussed.

Weibull distribution has been used widely by many researches around the world especially in the analysis of high voltage experimental data. Unfortunately, the statistical techniques used to analyse the high voltage experimental data are not highly accurate. In view of the foregoing, this paper presents a new statistical approach to analyze the tree inception voltage of silicone rubber and epoxy resin. The tree inception voltage of silicone rubber and epoxy resin was measured via camera-equipped online monitoring system. The leaf-like specimen was used as test sample. AC ramp voltage was applied to obtain the tree inception voltage of silicone rubber and epoxy resin. It was observed that, the electroluminescence emission and ultraviolet (UV) radiation occurred indicating the early stage of tree occurrence. The obtained results were analysed statistically by using fitting method. Anderson-Darling goodness-of-fit test was performed in order to obtain the best fitting distribution. Comparison was made between the best-fitted distribution and Weibull distribution. Based on Anderson-Darling tests, the tree inception voltage of silicone rubber and epoxy resin was best fitted with Johnson SB distribution. Based on this fitted distribution, the value of tree inception voltage for silicone rubber and epoxy resin was calculated and equalled to 11.80 kV and 20.11 kV respectively. From this study, it was found out that the best-fitted distribution for the value of tree inception voltage for silicone rubber and epoxy resin is the Johnson SB distribution by means of Anderson-Darling goodness-of-fit test.

Electromagnetic pulses produced by lightning return strokes travel both above and underground for long distances. Lightning electromagnetic pulses are caused significant effects and disturbances on the function of nearby systems such as power, communications, and etcetera. Electromagnetic fields are propagate into both above and underground for long distances. This study purposes to increase the comprehensive about the effect of distance on the lightning electromagnetic propagation over frequency-dependent soil. The modified transmission line with exponential decay (MTLE) model is used to model the lightning return stroke channel. The return stroke, and electromagnetic propagation models were modeled using RF-Module in the form of finite elements analysis via COMSOL software. The studied electromagnetic components are radial electric field, vertical electric field and azimuthal magnetic field with various distance from lightning channel. Furthermore, their behaviors with different soil water content up to 100% were as well studied. Peak values, wave shapes, and polarities of the above/using frequency domain solvers under ground electric and magnetic fields are influenced by distance from lightning channel. The aboveground fields are differently affected by the soil water content for various distances. In contrast, the behaviors of soil water content of underground fields are non-significantly affected by the distance from lightning channel.

Rapid economic developments have forced power networks and pipeline networks to share the same pathway. Induced voltages and currents appear on pipelines running parallel with high voltage transmission line when the transmission line is hit by lightning strike. In this study, a simulation had been carried out to determine the first lightning stroke effect on an underground pipeline coating stress. CDEGS software was used to solve Maxwell equations; in particular, HIFREQ and FFTSES tools were utilized. A 2-km underground pipeline and a 345-kV transmission line (TL) tower had been modeled. A suitable TL-pipeline distance need to determined based on lightning current, surrounding soil properties, and coating withstand voltage. In addition, horizontal and vertical rods are able to reduce the overvoltage across the coating. The first layer soil resistivity and thickness are important factors to be considered when carrying out mitigation in a non-uniform soil.

Lightning locating system (LLS) is employed to detect lightning occurrences in single station or multi-station systems. There is a variety of lightning locating systems based on the detection of propagated electromagnetic signals of lightning discharge. A parallel plate antenna is used to receive the vertical components of the electric field. The antenna is connected to a buffer circuit by a coaxial cable. The buffer circuit acts as a filter, an over voltage protector, and an impedance matching. A Global Positioning System (GPS) is also installed to capture the time stamps of received signals in sub nano-second precision. Each station is made up of hardware and software implementations. The hardware component of each station consists of a parallel plate antenna which is selected because of its ability of detecting the vertical component of the lightning electric field in a wide range of frequencies. A Matlab program is written to solve the non-linear equations for the lightning locating system based on the detected arrival times using measuring stations. Several lightning measuring stations will be designed, constructed and installed. This study investigates the hardware design, testing and installation of the stations.

Multi-cell batteries play crucial role in satellite operation by ensuring power storage capability. However, due to their higher failure rates, battery management systems are used in satellite batteries to perform cell balancing, monitoring and protection to avoid over/under voltage. This ensures safe operation and prolongs battery life. The conventional methods use inadequate dissipative techniques causing excessive heating and power losses in the batteries. This paper proposes a scalable, modular and optimal design technique for battery balancing. This proposed design performs cell balancing using an intelligent passive cell balancing technique based on Texas Instruments BQ77PL900. The results have shown that the design is the economical yet effective solution for the given problem having low power consumption along with high reliability.