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The hot-spot temperature is a key parameter in transformer loading management. It plays a significant role in evaluating transformer winding thermal performances, as well as in the determination of winding insulation’s loss of life. A simplified winding thermal model has been developed based on the presented methodology in favour to reduce real-world model complexity. A conjugate heat transfer has been approached to solve the cooling effects of natural oil convection. Results show a good agreement with only 3.1% percentage difference for the average winding temperature between the newly developed winding model and manufacturer factory-end test report. The plotted graphs of oil flow and thermal distributions showed a unique relation between localised hot-spot temperature and oil flow patterns. The hottest temperature and its location are well pronounced with the inclusion of eddy current loss distribution within winding height. The proposed methodology can be used to investigate the oil cooling scheme of transformer winding and allows the manufacturers to optimise their thermal design.

Solar energy is an intermittent energy source that varies throughout the day and seasons, thereby affecting the overall power system stability. In order to reduce this impact, the solar tracking system can be incorporated, which increases the system energy yield with less silicon consumption. This paper deals with the design and construction of dual-axis solar tracking system based on an astronomical algorithm. The angle sensor is used as feedback in the solar tracking system, which is the combination of accelerometer and gyroscope to measure yaw and tilt angle of the panel. A dual-axis mounting structure is designed by using Solid Works software and constructed with DC motors and worm gear to drive the solar PV panel. The developed astronomical-based algorithm for dual axis solar tracking system has been verified with a sun path chart.

Bioelectricity is one of the high potential alternatives for sustainable energy production. Bioelectricity generated from living organisms including plants and bacteria has been discussed and explored by researchers in the past decades. Several methods of electrical energy harvesting had been researched and developed with living organisms as the sources of energy including plant microbial fuel cell (PMFC) and plant-based cell (PBC). It was recognized that electrical energy can be harvested from living organisms and has great potential. Aquaponics on the other hands is known as the combination food production system involving aquatic species, plants, and bacteria, where it has the elements needed for bioelectricity generation. This paper will review the potential of harvesting electrical energy from living organisms at the aquaponics system and recommendations for future works.

The use of solar energy to generate electricity has had a significant increase in recent years, and it is considered a modern energy source, as its market price is decreasing and is in constant development. However, other countries suffer from a huge shortage of electric power generation. Iraq generates half of its electricity demand, and it only supplies 12 hours of electricity a day for one area to meet this demand. This study discusses the sizing of a PV system to cover the shortage of electricity for one residential quarter which contains 20 houses. Moreover, the initial cost of installing the PV system is calculated to cover the shortage of electricity. Specifically, the study covers a residential quarter in Samawah.

Multilevel inverter (MLI) becomes more significant in Active Power Filter (APF) application due to capability to its produce low harmonic output current in which at the same time improving performance of APF. Among the topologies of MLI, Cascaded H-Bridge (CHB) is the most popular topology with less power devices requirement and simple design. MLI CHB is also capable to produce possible output voltage at twice of the number of DC source which in this case of APF is the best suited topology to replace with the conventional six -step inverter. This paper presents the performance of three- phase three-wire CHB MLI used in Shunt Active Power Filter (SAPF) based on Direct Current Control (DCC) and Indirect Current Control (ICC) schemes. Both schemes are developed and verified in MATLAB/Simulink. The simulation results show that both current control algorithms are capable to mitigate load current with Total Harmonic Distortion below than the permissible value based on IEEE 519 standard.

In this paper a model has been proposed to investigate the effect of Standard Lightning Impulses at voltages below the Basic Insulation Level (BIL) on winding geometry, based on the extraction of resistances, inductances, capacitances and conductance using Finite Element Method (FEM) and the resultant structural movement. The winding and insulation in a transformer can be subjected to overvoltage surges i.e. lightning strikes and switching events. If the frequency component of the incoming transient surges matches the resonance frequency zone of the transformer windings, the amplification and attenuation of the overvoltages along the windings may result in abnormal voltage stress on the conductors of the winding. Hence, the monitoring of electromagnetic forces and the resultant mechanical stresses are of paramount importance in the minimization of the occurrence of mechanical failure in transformers. The Standard Lightning Impulse (SLI) was induced at the outermost layer of the High Voltage (HV) winding of the 11/0.415 kV transformer and resultant electromagnetic forces acting in axial and radial directions were computed. The computed directional forces were in turn induced to the winding structure to observe the structural behavior. The FEM model was tested using an SLI with a voltage, 35 kV, below the BIL of this class of transformer. The modeling showed that the axial and radial forces impinge a mechanical stress in the outer column supports of the winding structure. This model will allow the investigation of buckling within windings at elevated voltages above the BIL.

Energy is a basic necessity in every country. The worldwide demand for energy will rise due to the developments of power generation in industrial, service, and residential sectors. A healthy power system is therefore very important to guarantee continuous electricity supply to the end users and this can be achieved through asset management. A proper asset management will allow asset managers to conduct quality assessment of conditions and to develop future management strategies of the electrical assets such as transformers. The execution of transformer asset management involves an investigation of the transformer's condition by employing Transformer's Health Index (THI). Mathematical equation/algorithm or expert judgment has been investigated by many previous studies as one of the technique to determine health index (HI). Some of the established methods of HI determination such as scoring and ranking method, tier method, matrices and multi-feature assessment model have led to the different interpretations of the final condition of a transformer. This paper critically examines and explores the previous studies related to transformer health index by using mathematical equation/algorithm or expert judgment. The concept of HI and its formulation are presented in this study. Generally, there are three parts of HI formulation which are input, algorithm for HI and the output of HI. The application of HI is discussed in terms of the performance of in-service transformer. The limitations of the available methods are also discussed and future works to overcome the problems are suggested.

The down conductor system is one of the essential components besides the air termination system and the earth termination system, since that the objective of this study is to investigate the effect of different type of down conductor materials on the varying angles of down conductors with different separation distances due to lightning strike. There were numerous materials of down conductor utilized worldwide in the Lightning Protection System (LPS) installation. In this circumstance, the aluminium and galvanized steel materials are taken into consideration to be resolved with reference to the electric field profile. The accomplished whole system of Lightning Protection System (LPS) for sheltered structure, is being modelled that abide by the standard of MS IEC 2007. Further, this entire system is modelled based on the outstanding of soil resistivity grounding parameter. Consequently, it is found that the galvanized steel material is more critical than aluminium in most angles due to the higher electric field intensity.

The importance of flexible power flow control in electric power transmission networks is increasing owing to many factors that have arisen. Sen Transformer (ST) is one of the attractive power flow controllers. It has a wide control range, independent active and reactive power flow control capability, and is economically attractive. However, it operates in stepwise mode, has limited operating points, relatively slow response rate, and suffers from compensation error. Motivated by the limitations of the ST, power transistor assisted ST (TAST) as a novel power flow controller is proposed in this paper. The TAST consists of a highly-rated ST and a lowly-rated AC chopper based transistorized ST (TST). This paper first points to the importance of transmission lines’ power flow control and reviews available power flow control devices. It then introduces the proposed TAST, determines the ratings of the TST and the switching pattern of its choppers. Next, it demonstrates the steady-state performance of the TAST, determines its control limits, compares the TAST to the ST and the unified power flow controller (UPFC), and the different control strategies of the TAST. In this paper, the TAST is modeled in MATLAB/SIMULINK and tested in an equivalent two bus system and in the IEEE-14 bus test system. The work also demonstrates improvement of the response rate of the ST. Cost analysis of the TAST is also done and is compared to that of the equivalent UPFC. Based on the results, the TAST realizes continuous, error-free, more flexible operation, improved response rate, and low cost. Moreover, the TAST provides 14.62% wider power flow control range. In conclusion, the TAST's operational characteristics are closely comparable to that of the UPFC with the advantage of lower cost and extended control area.

In recent years, there are a number of studies that have been carried out to explore the alternative for Mineral Oil (MO) as dielectric insulating fluid in transformers due to the increasing tight regulation on safety and environment. Vegetable oils have been identified as suitable candidate since it is biodegradable, non-toxic and high flash/fire points which ensure more in-service safety. Among the types of vegetable oils considered for transformers application are Palm Oil (PO) and Coconut Oil (CO). This paper presents an experimental study on the lightning breakdown voltages of PO and CO under non-uniform electric field based on needle-sphere electrodes configuration at 3 small gap distances. The type of PO used in this study is Refined Bleached and Deodorized Palm Oil (RBDPO) Olein. The main focus of this study is to examine the lightning breakdown performance of RBDPO and CO under different test conditions and assess its suitability as dielectric insulating fluid in transformers. The effect of voltage polarities (positive and negative) and testing methods (risingvoltage, up-and-down and multiple-voltage) were investigated. The data obtained from all tests were analysed by Weibull distribution in order to determine the withstand voltages for each type of oils. It was found that the breakdown voltages of RBDPO and CO are comparable with MO under positive lightning impulse. Under negative lightning impulse, the breakdown voltage of MO is slightly higher than RBDPO and CO. There is no significant effect of testing methods and voltage polarities on lightning breakdown voltages of RBDPO and CO. Based on the statistical analysis, it is found that the breakdown voltages of RBDPO and CO at 1% probability are slightly lower than MO.

In the event of a direct lightning strike to a protected building which is integrated with an electrical or electronic system installed on the roof such as roof-top PV system, dangerous arcing may occur between the external lightning protection system (LPS) and the conductive components of the electrical system. To prevent such side flashes, a minimum separation distance between the metallic components and the air termination system is required. Even though, IEC62305-3 Standard provides a formula to specify the necessary separation distance, so far there is no extensive study that has been done to evaluate the suitability of the application of equation to calculate the separation distance, specifically to the safety of electrical systems integrated into the roof top of building. In this study, a new computational method has been developed for calculation of the separation distance between an LPS and metallic components on the roof. In the proposed method which is based on the theoretical background of the IEC62305-3 Standard formula, the break down behavior of the gap geometry between the LPS and the metallic components for the applied voltage across the gap is analyzed. PSCAD software was used to model the LPS and the lightning strokes.

In recent years, there have been a number of interests on the Palm Oil (PO) and Coconut Oil (CO) as a potential alternative dielectric insulating fluid in transformers which stimulate different types of studies on these oils properties. Among the important studies is the lightning impulse properties. This paper presents the investigation on the lightning impulse breakdown voltage of PO and CO under non-uniform electric field. The PO used in this study is Refined, Bleached and Deodorized Palm Oil (RBDPO) Olein type. The influence of the testing methods, rising-voltage and up-and-down are investigated at 2 gap distances for both oils. It was found that the lightning breakdown voltage performance for some of the RBDPO and CO are comparable to MO.

This paper is to study the effect of electric field on an angle variation of copper down-conductor due to voltage and current transient. Down-conductor which informs of numerous material, shape and dimension are mandatory for diverting the lightning current from air termination system to the grounding system in sheltered building. Hence, a numerical analysis method is applied emulating the comprehensible and particular model according to ordinarily used in the manufacturer’s datasheet specification. A rigorous assessment in term of electric fields was reviewed in comparison with the critical breakdown value of air for a crucial study. Later, a foremost angle is proposed for the installation of down-conductor in order to achieve a reliable protection system.

Allocation of flexible AC transmission systems (FACTS) devices is a challenging power system problem. This paper proposes a new particle swarm optimisation (PSO) variant, called enhanced leader PSO (ELPSO), for solving this problem. This algorithm is capable of solving FACTS allocation problem in a way leading to lower amounts of power flow violations, voltage deviations and power losses with respect to other optimisation algorithms. Distributed thyristor controlled series compensators (D-TCSC’s) are used. D-TCSC’s are installed at all branches except those with regulating transformers. The reactances of D-TCSC’s are found in optimisation process. ELPSO features a five-staged successive mutation strategy which mitigates premature convergence problem of conventional PSO. ELPSO and other optimisation algorithms are applied to IEEE 14 bus and 118 bus power systems for N-1 contingencies and also for simultaneous outage of four branches. The results show that it leads to lower amounts of power flow violations, voltage deviations and power losses with respect to conventional PSO (CPSO) and eight other optimisation algorithms including genetic algorithm (GA), gravitational search algorithm (GSA), galaxy based search algorithm (GBSA), invasive weed optimisation (IWO), asexual reproduction optimisation (ARO), threshold acceptance (TA), pattern search and nonlinear programming (NLP).

Protection of medium voltage (MV) overhead lines against the indirect effects of lightning is an important issue in Malaysia and other tropical countries. Protection of these lines against the indirect effects of lightning is a major concern and can be improved by several ways. The choice of insulator to be used for instance, between the glass, ceramic or polymer, can help to improve the line performance from the perspective of increasing the breakdown strength. In this paper, the electrical performance of a 10 kV polymer insulator under different conditions for impulse, weather and insulator angle with respect to a cross-arm were studied (both experimental and modelling) and the results were discussed accordingly. Results show that the weather and insulator angle (with respect to the cross-arm) are surprisingly influenced the values of breakdown voltage and leakage current for both negative and positive impulses. Therefore, in order to select a proper protection system for MV lines against lightning induced voltage, consideration of the local information concerning the weather and also the insulator angles with respect to the cross-arm are very useful for line stability and performance.

This paper presents a study about electric field behaviour of 10kV polymer insulator with moss deposition under foggy condition. The aim of this simulation experiment was to determine if this field affect the initiation of pollution flashover. To study this effect, simulations were carried out using High Frequency Structure Simulator (HFSS). The simulation experiment includes the results of electric field distribution along the insulator and also the magnitude of electric field at three different locations in identifying the parts of the insulator’s surface that likely to initiate pollution flashover. The moss deposited polymer insulator displayed uniformed and considerably intense distribution of electric field with the clean insulator. The field result showed the likelihood in discharging a corona effect. In short, the results indicated that electric field along the insulator surface would likely be influenced by moss deposition and foggy air.

Electricity generate from the wind has been increased around the world. This development is related to more advantages of wind rather than conventional power plants. These advantages include the environmental and economic benefits. Beside these advantages there is some risk for investors. The intermittent and fluctuation nature of wind cannot allow the investors and operators determined the amount of these valuable energy. The term capacity value has been used for long term planning. Capacity value directly affects the generation cost. If capacity credit is low (low wind regime), the possible energy generation cost will be high and vice-versa. In this paper, proposed a method to determine the capacity value by using the probability distribution function of wind speed, and then evaluate the amount of electricity generate seasonally by wind turbines in a specific area. And finally, an error correction factor will be offered for wind investors.

To increase the maximum possible benefits of technical, economic and environmental aspects, the optimal sizing and sitting of distributed generation in distribution system has always been challenging for customers as well as to utilities. The objective of optimum sitting of distributed generation in a distribution system is to reach suitable operation of such systems with minimization losses of the systems, voltage profile improvement, enhanced system load ability, stability and reliability. In this paper, a review of techniques for optimum sitting of distributed generation units in distribution systems and study their effects on customers and utilities are presented. Also, a comparison was done between methods for optimum location of distributed generation in distribution systems.

This study analyzed and compared the lightning related casualties in Malaysia and United States. United States as a developed country is reported with 0.3 deaths per million per year after 1970 comparing to lesser-developed areas such as Malaysia with an annual lightning fatality rate of 6 deaths per million. The comparison and analysis were made based on the rural-urban setting and the six types of activities locations defined as agriculture, indoors, outdoors, recreation, small structures (i.e. vehicle, open-sided shelter, shed) and sports. The results for the both countries were discussed in terms of their differences and similarities.

Wind power has remarkable economic and environmental advantages when compared to other power generation sources. Presently, wind power is considered to be an essential alternative source for generating power. The growing pervasiveness of Wind Energy Conversion System (WECS) in power systems has a huge influence on the electrical system’s reliability in relation to other conventional sources for power generation. If the variation in the speed of the wind of a specific site is significant, then, the power output from the wind turbine may get severely affected. The output power from the WECS may also get affected by the unavailability of wind generating units for a considerable period of time. The impact of wind turbine units on the reliability of power generating systems and operating reserves is explained in this paper, while considering wind power units that are frequently unavailable and for a considerable amount of time. The paper presents the impacts of the duration and frequency of failures of the Wind Turbine Generators (WTGs) on the WECS output power. A Sequential Monte Carlo Simulation (SMCS) technique along with Frequency and Duration method shows it is effective for estimating the WECS output power, and the simulation was conducted on IEEE RTS-79 bus system.

This paper presents an investigation of the condition state distribution and performance condition curve of the transformer population under different pre-determined maintenance repair rates based on the Markov Prediction Model (MPM). In total, 3195 oil samples from 373 transformers with an age between one and 25 years were tested. The previously computed Health Index (HI) prediction model of the transformer population based on MPM utilizing the nonlinear minimization technique was employed in this study. The transition probabilities for each of the states were updated based on 10%, 20% and 30% pre-determined maintenance repair rates for the sensitivity study. Next, the HI state distribution and performance condition curve were analyzed based on the Markov chain algorithm. Based on the case study, it is found that the pre-determined maintenance repair rates can affect the HI state distribution and improve the performance condition curve. The 30% pre-determined maintenance repair rate gives the highest impact, especially for the transformer population at state 4 (poor). Overall, the average percentage of change for all HI state distributions is 16.48%. A clear improvement of HI state distribution is found at state 4 (poor) where the highest percentage can be up to 63.25%.

This research focuses on the simulations of the effect of corona model on different conductors used in transmission line design when subjected to the lighting surge. The paper details the procedures used in modelling the corona, as well as the implementation in the PSCAD/EMTDC Software for surge propagation studies. There are many models available range from a simple and fixed capacitance to the more complex voltage-dependent capacitance. The corona used for this study is modeled based on the approached relationships and the analyses were done by comparing the results with other models for different types of conductors. The traveling voltage is then measured at different point-of-interest (POI) and compared in terms of the steepness and magnitude for different conductors.

The withstand capability of the insulation system of an equipment under lightning overvoltages is measured by the international standard 1.2/50I¼ s waveform. Many workers and designers of the power apparatus equipment have dedicated their research tried to understand how the insulation behaves under the non-standard waveform. The fact that the lightning-caused transient voltage can have very fast components and the need for higher reliability and cost effectiveness have added the impetus in recent years to better understand the effects of a non-standard lightning voltage on the power system. As far as the lightning is concerned, much attention has been paid to the breakdown occurring at extremely fast rise times, which could be in nanosecond regime. This research provides some reviews on the non-standard waveform of the lightning and focuses on the simulation of the effect of the non-standard lightning current and waveshape on lightning surge analysis using the PSCAD/EMTDC software.

Dissolved Gas Analysis (DGA) is one of the common approaches that can be used to detect incipient faults in transformers. According to IEEE C57/104-2008 and IEC 60599 standards, there are many DGA techniques that can be used to interpret the type of faults. In this paper, an alternative method to diagnose faults in transformers based on Rough Set (RS) and Fuzzy Logic (FL) is proposed. The rules for the FL are generated from the attributes of RS. Based on this method, it was found that the efficiency of the fault interpretation based on RS/FL is improved compared to the conventional methods in standards.

This paper reviews a study of the inclination angle of an insulator due to mechanical forces imposed by overhead conductors. The angle theoretically shortens the effective leakage path and flashover distance of the insulator, thus change the electrical performance of the insulator. To take it into consideration, this study had focused on experimental works to investigate effect of insulator inclination to the breakdown voltage and leakage current. Regards to the important of wetness to improve surface conductivity of insulator surface, authors have considered to conduct the test in wet conditions. In addition, standard lightning voltage was applied according to IEC 60060 in both positive and negative impulses. Based on the test, the performance of an insulator under positive and negative impulses was compared accordingly. A significant reduction of breakdown voltage was recorded when the angle decreased. The reduction was recorded as high as 17 %. Meanwhile, the breakdown voltage was much higher under negative impulses compared to positive impulses which showed a difference of 12 % to 14 % and the leakage current increased by 17 % due to the inclination angle. The calculation of U50 with consideration of the reduction factor was suggested and briefly discussed.

Liquid insulation plays an important role for the lifespan of the oil-filled transformer. Liquid insulators not only insulate the live parts of the transformer, but also act as cooling agent for better heat agglomeration when the transformer being energized. Petroleum-based mineral oil has become dominant transformer oil for more than a century for its excellent dielectric properties. Considering the source is derived from nonrenewable energy, researchers have been putting up efforts to develop a comparable or better substitutions for conventional transformer oil. Palm oil and coconut oil are the examples of potential alternative transformer oil for its advantage whereas it is derived from environmentally friendly sources and also renewable. However, before these type of oil can be implemented in service transformer, it is crucial to examine the behavior of the electrical properties which is the most important parameter; the AC breakdown voltage. Thus in this study, the breakdown voltage of palm oil and coconut oil are investigated. Result indicates that palm oil and coconut oil have fairly similar AC breakdown strength and withstand voltages. However, palm oil possess higher deviations in data compared to coconut oil that will make it less reliable in withstand voltage prediction.

Site dependent parameters such as soil resistivity, maximum grid current, fault duration, shock duration, surface layer material resistivity, and grid geometry have substantial impact on the design and performance of an earth grid. The grid geometry, i.e. the area occupied by the grid system, conductor spacing and the depth of burial of earth grid specifically have much impact on the mesh, step, touch voltage and earth potential rise, while parameters such as the conductor diameter and the thickness of the surfacing material have less impact on the safety criteria. In this paper, a distribution substation earth grid was designed using the CDEGS software by varying the spacing between grid conductors (compression ratio) from 1 to 0.5 in steps of 0.1. The safety criteria were studied under three scenarios, without surface layer material, with surface layer material of resistivity 3000Ω-m, and surface layer material of resistivity 5000Ω-m. Results indicated that the grid resistance and earth potential rise were lower for a compression ratio 0.9, while the step and touch voltages were found to be similar for each case of surface layer material.

Among the alternative fluids considered for application in transformers are Palm Oil (PO) and Coconut Oil (CO). Among the important studies that need to be carried out before it can be applied in-service is the lightning impulse performance. This paper presents the experimental work on the lightning impulse breakdown voltage of different PO, CO and Mineral Oil (MO). The PO used in this is the Refined Bleached Deodorized Palm Oil (RBDPO) type. The test was carried out under quasi-uniform field using sphere-sphere electrode configuration with different testing methods (rising-voltage and up-and-down). It was found that the lightning impulse performance for some of RBDPO and CO were comparable to MO.

The effects of electromagnetic fields(EMF) due to high voltage line on the parallel pipeline are not a common issue nowadays. The EMF will bring up some pipeline problems and safety issues. There are only a few of previous studies about EMF effects consider in the lightning fault parameter and study in term of currents. This means the EMF effect of the transmission line to the pipeline still not completed. A study has been carried out to determine the effect of electromagnetic field in term of voltage and current of the shared corridor between the transmission tower and the pipeline. This study is simulated by using ANSYS Maxwell software. The induced voltage obtained is in the range of 2.6089V to 4.7723V which within the maximum acceptable value (15V) of IEEE 80-2000 standards. The induced current obtained is in the range of 3.1893nA to 61.4640 nA. Besides, mitigation is also discussed.

This paper presented a hybrid method to find the optimal size of the distributed generation by considering different type of renewable sources in the distribution power system. The proposed method is based on the combination of two methods like the sensitivity analysis and continues power factor method. The simulated method is done on the Matlab environment by applying in the 16-bus distribution system. The result illustrated the accurate and reliable size of the different types of the distributed generation in a power system.

The increasing interests on the Palm Oil (PO) and Coconut Oil (CO) as a potential alternative for dielectric insulating fluid in transformers encourage a number of researches on different aspects of these oils. Among the common areas under study is the lightning breakdown voltage. In this paper, the lightning breakdown voltage of PO and CO is examined. The type of PO used in this study is Refined, Bleached and Deodorized Palm Oil (RBDPO) Olein. The testing was carried out under non-uniform electric field using needle-sphere electrodes configuration. The influence of the testing methods, rising-voltage and up-and-down on the breakdown voltages are investigated for both types of oils. It was found that the lightning breakdown voltage performance for some of the RBDPO is comparable to Mineral Oil (MO).

Reduction of active power loss is one of the main functions that are carried in power system control centers. The main purpose of transmission systems is efficiently handling power from generation stations to load centers. Yet, a considerable amount of power is lost in transmission network components. As a corrective action, power flow redistribution in transmission lines using appropriate power flow control devices is useful to increase the transmission efficiency. However, the inserted power flow control devices themselves consume power. Thus, if not optimally sited, their own power loss may overcome the loss reduction which is obtained by their action, and as a consequence may increase the power loss further. Optimal allocation of these devices is critical to ensure fulfillment of the proposed goals. In this work, optimally placed Sen Transformer (ST) is suggested for power loss reduction considering security constraints. ST is modelled under MATLAB/SIMULINK, and optimally located using active power loss sensitivity index. The method is validated using IEEE-6 bus system and the results are encouraging.

Energization current is a fundamental consideration in designing of distribution substation earth grid. Arbitrary choice of energization current in earth grid design process may lead to technical and economic implications resulting in underestimated or overestimated designs. In this paper, a distribution substation earth grid was designed using SESCAD and executed in MALT module of CDEGS. The energization current was varied by 100, 75, 50 and 25% of the short circuit current available at the secondary terminals of the upstream transformer to determine the impact on safety criteria of the earth grid. Results indicated that, the EPR for 100% fault current was higher, whereas the step and touch voltages were lower. Also, compared to the other cases of short circuit currents, there was no difference in step and touch voltages when the energization currents were varied at 75, 50 and 25%.

One of the most crucial prerequisites for effective wind power planning and operation in power systems is precise wind speed forecasting. Highly random fluctuations of wind influenced by the conditions of the atmosphere, weather and terrain result in difficulties of forecasting regardless of whether it is short-term or long-term. The current study has developed a method to model wind speed data predictions with dependence on seasonal wind variations over a particular time frame, usually a year, in the form of a Weibull distribution model with an artificial neural network (ANN). As a result, the essential dependencies between the wind speed and seasonal weather variation are exploited. The proposed model utilizes the ANN to predict the wind speed data, which has similar chronological and seasonal characteristics to the actual wind data. This model was applied to wind speed databases from selected sites in Malaysia, namely Mersing, Kudat, and Kuala Terengganu, to validate the proposed model. The results indicate that the proposed hybrid artificial neural network (HANN) model is capable of depicting the fluctuating wind speed during different seasons of the year at different locations.

The growing pervasiveness of the Wind Energy Conversion System (WECS) in power systems has a great influence on the electrical system reliability in relation to other conventional sources for power generation. This current study offers a binary particle swarm optimisation (BPSO) application with Weibull model to reliably evaluate the generation systems with a WECS. The proposed methodology is based on hourly time series wind speed and uses Weibull model and simulation of the operation of generation system, taking into consideration the random failures of conventional units of the system and the fluctuating wind energy of a WECS. The BPSO algorithm adopts intelligent research to explore the meaningful system states and accelerate their integrated convergence, so that makes it feasible to locate all possible failure states in the system states space in order to calculate the reliability indices with WECS. The numerical simulation of the suggested solution is compared with the established Monte Carlo simulation (MCS). The reliability test system (IEEE-RTS-79) is employed to show the effectiveness of the proposed algorithm.

This paper presents a characteristic of lightning electric fields. The lightning electric fields captured by two parallel plats sensor and the characterization for preliminary breakdown pulse (PBP) and first return stroke (RS) were studied. A total of 207 data were recorded and 10 data are selected and been utilized in this paper accordingly. In PBP signal data, time before return stroke, ending time and maximum peak of PBP were analyzed. The time duration between the PBP and the occurrence of RS was obtained as 0.64 ms and 2.61 ms and then compared with results from other researchers. For RS signal data, slow front time, deviation time, RS peak, time to peak, zero crossing time and 10% to 90% rise time were evaluated meticulously and the results were discussed accordingly. Moreover, the statistical correlation between electric field zero times and corresponding rise times was studied.

Split factor is a fundamental consideration when designing a distribution substation earth grid. Arbitrary choice of split factor in earth grid design process may lead to technical and economic implications resulting in underestimated or overestimated designs. In this paper, a distribution substation earth grid was designed using SESCAD and executed in MALT module of CDEGS. The energization current was varied by 100%, 75%, 50% and 25% of the short circuit current available at the secondary terminals of the upstream transformer to determine the impact on safety criteria of the earth grid. Results indicated that, the EPR for 100% fault current was higher, whereas the step and touch voltages were lower. It was also revealed that, there was no difference in step and touch voltages when energization current was set at 75%, 50% and 25%.

Down-conductor is part of critical component in the external Lightning Protection System (LPS) as to divert the lightning current from the air termination to the earth termination system of protected structure. In this paper, numerical analysis approach incorporating the effect of copper conductor bending angle under current transient and voltage is utilized. Various angles of copper conductor will be synthesized following a simplified and generic, but meticulous, model based on the manufacturer's datasheet specification which is normally used. The fields were analyzed and the results were discussed in comparison with the MS IEC 62305-3 standard accordingly. In this case, the cross-sectional area of down-conductor was selected based on the accessible type produced by various manufacturers as proposed by the MS IEC 62305-3 standard for a critical study. This study presents the optimum angle of down-conductor with a view to develop a practical approach and to set the down-conductors in a confined area locations of a building.

The continuous increase of power demand stresses the system, and adversely affects its security. It may lead to components overload and their outage, voltage decline and its collapse, which may cause entire system blackout. As well, the normal flow of power in transmission lines is not the best possible. In this paper, the Phase Angle Regulator (PAR) and Sen Transformer (ST) are suggested to be used for better utilization of the transmission lines, and to enhance power system security. In this work, the PAR and ST are modelled, and connected in a five bus test system using MATLAB/SIMULINK. The simulation results showed validity of both PAR and ST, and the superiority of ST, since it enhances both power flow and voltage security. Based on the results, the new emerging smart power and voltage control device ST is a very effective tool that can be combined into Smart Grids (SGs). It is found that, usage of ST not only manages line flow congestion and maintains bus voltage, but also increases overall efficiency.

Design of distribution substation earthing grid can be very challenging in high resistivity soils especially in two layer soils where the top layer resistivity is lower than the bottom layer. This paper presents the design of a distribution substation earth grid using Current Distribution Electromagnetic Field Grounding Soil Structure Analysis Software (CDEGS). Soil resistivity measurement was carried out at the substation site using a 4-pole Megger earth tester based on Wenner method. The soil structure was determined using RESAP module, while the design was implemented using SESCAD and executed by MALT module. Results indicated a slight reduction of earth grid resistance, 0.6%, 5.8% and 6.5%, respectively as the grid burial depth was varied from 0.5m to 1.5m in steps of 0.5m. The touch and step voltages were found to be lower when surface layer material was not applied and higher when surface layer materials of 3000Q-m and 5000Q-m resistivity were interchangeably applied on the grid surface. It was also found that, the calculated earth grid resistance from IEEE Std. 80-2000 equation was lower than the grid resistance computed by MALT.

This paper investigates the effect of design parameters on the induced voltages on a distribution power line. This investigation is based on perfect ground conductivity, single stroke lightning and lightning without branches. The design of the parameters includes, d, the striking distance of the lightning, h, the height of the conductor, and r, the diameter of the conductor, all of which are elements that produce the variations in the induced voltage on a distribution power line with respect to a vertical or an inclined lightning channel. Thus, the outcome of this investigation can act as a guide for utility companies or other power engineers in order to plan an appropriate protection scheme for a distribution power line.

The ability of power system to maintain steady voltage at all the buses after happening a disturbance from a given initial operation condition is defined the voltage stability in the system. The focus of this paper is on voltage stability monitoring using the generalized regression neural network by improving algorithm. In this paper, to identify load buses and certain operation condition, the static voltage stability method in power systems is presented. Based on load buses, the index of voltage stability is obtained from the voltage equation derived from a two bus network. The proposed methods are tested on the IEEE-14 bus test system.

Lightning can create lightning induced overvoltage (LIOV) on a power line. However, detailed considerations are needed concerning the evaluation behaviour of LIOV due to changes in channel angle which is referred to as an inclined lightning channel. The aim of this paper is to evaluate the behaviour of LIOV due to variations of channel angle. The LIOV was generated through the execution of an algorithm in MATLAB. Results indicate that the behaviours of LIOV are direct and show a linear relationship with an increasing channel angle which is an inclined angle and observation point angle. On the other hand, the effect on the LIOV of an increasing channel angle due to the return stroke velocity decreases at the highest velocity. As a result, the outcome of this paper could be useful for electrical power designers for the fast estimation of LIOV peak voltages without recalculation of the LIOV and to assist in the appropriate planning of protection schemes.

FACTS optimisation is one of the most important and difficult problems in power systems. For solving this problem, so many different approaches have been proposed in the literature. Among them, particle swarm optimisation (PSO) has exposed so promising behavior. In this paper, applications of PSO in FACTS optimisation problem are explained and analysed from the viewpoint of the objectives, used basic PSO variant, PSO parameter selection, multi-objective handling, constraint handling and discrete variable handling. Eventually, some hints for future research is provided.

By increasing the global warming and environmental challenges the industrial countries commit to reduce the gas emissions and develop the renewable energy based on the Kyoto protocol and also renewable portfolio standard (RPS). Among them, wind resources are more important because of the progress in the technology of its facilities to convert wind to electricity. Wind turbines manufacturer companies improve the efficiency of their facilities during the last decade. On the other hand, the wind generator firms and investors intend to select a suitable wind turbine generators (WTGs) based on the wind distribution in a specific region. In this study, Output power (MW) of four different types of WTGs has been compared. The wind speed data has been collected for 10 years from 2000 to 2009 from Canada Swift Current region. Then, the model of wind speed has been predicted with ARMA time series. In the next stage, the output power of each WTG has been determined with probability method. Finally, the suitable WTG is recommended according to the output power produced.

The necessitation in the optimal power demand model, make it an impetus to present this work as a glaring path in determining the optimum power demand curve, using the available data of a substation. The data are used to find the equation and its coefficients of determination that can give the best-fit curve of the power demand of a substation, based on the available data. This will produce a model that can be validated by comparing the data and figured out the equation.

This paper investigates the influence of inclined lightning channel on induced voltage on the line. The angle variations of inclined lightning channel may cause the voltage to be induced at different values for different points along the power line. This behaviour may affect the line's lightning performance if the peak of induced voltage is greater than the critical flashover voltage (CFO) of the line. This induced voltage is expected to be increased when the inclined angle with respect to the observation point is decreased. Appropriate method of induced voltage algorithm with respect to the incline lightning channel will be developed and compared with other method. The outcome of this study would be useful for the utility for their planning and selection of appropriate protection scheme for the line.

Grounding issues related to lightning currents have been addressed giving special attention to recommended practices in IEC 62305 (2010). Unambiguous recommendations are needed for the requirement of type A system or type B system or both systems for a given installation. Specifications of the length of conductors, based on the level of protection, were critically analyzed emphasizing the human risk related issues. Calculations reveal that at Level III and IV, the specified lengths of type A conductors may give step potentials, especially in highly resistive soils that may drive currents through human beings in the vicinity, exceeding lethal energy. Furthermore, specification of the limiting value of resistance for transient grounding systems may lead to hazardous situations as the difference between frequency dependent impedance and low frequency resistance may increase to very high values at Mega Hertz range where lightning energy spectrum has significant amplitude. Covering of a sizable surface area surrounding the grounding conductors with insulation material, is recommended as a practical solution to this issue.

Temperature, especially the hot spot temperature (HST) and top oil temperature (TOT), has played the important rule and became the most effective factor in determination of the insulation life of the transformer. The prediction of HST and TOT is very important for estimating the loss of life (LOL) of the transformer in power system. Therefore, an accurate technique is needed for solving the thermal models. This paper presents a numerical method which can accurately calculate the HST and thus provides an effective evaluation of LOL of the transformer. An alternative solution for solving the thermal model is proposed in this work and results are compared with the actual temperature, measured by fiber optic sensors and placed on the 30MVA power transformer.