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Huifang Yu, Quanbiao Xu, Sanming Zhang, Weijun Gao, Jianfeng Xu
Energy and Power Engineering, Volume 09, pp 654-686;

The energy efficiency design of the exterior wall in the buildings of the hot summer and cold winter zone of China should consider the heat prevention in summer and the heat insulation in winter. The self-insulation of the exterior wall is a more feasible design to satisfy the energy efficiency of buildings in the zone. However, the systematic research is urgently needed for the self-insulation of the exterior wall in the hot summer and cold winter zone of China. The paper tested the thermal performance of the common non-clay materials such as shale sintered hollow brick, sand autoclaved aerated concrete block, etc. by means of indoor experiments. The energy efficiency effect of the common materials was verified using dynamic calculation soft PKPM and several constitutions of exterior wall with different main bricks and insulation materials on the heat bridge were simulated, too. Besides, the tests of the thermal performance of exterior wall in real constructions were carried out to testify the practical effect of the recommended constitutions of exterior wall with different main bricks and insulation materials on the heat bridge. The conclusions are: the physical and thermal properties of the six non-clay wall material are better than the clay porous brick; the thermal performance of the non-clay brick can be improved obviously through the rational arrangement of the holes; shale sintered hollow brick after increasing the holes and rationalizing the hole arrangement and sand autoclaved aerated concrete block are recommended for buildings in the hot summer and cold winter area of China. The dynamic calculation results show that the thermal performances of the non-clay materials are all satisfied with the energy efficiency; The heat transfer coefficient of the exterior wall with composition ③, in which the main wall was sand autoclaved aerated concrete block and the material on the heat bridge was sand autoclaved aerated concrete plate, is the smallest among the three recommended compositions.
Energy and Power Engineering, Volume 09, pp 614-653;

Distributed generation (DG) is the future of energy. This technology allows the bidirectional flow of power within an electrical network. Researchers are faced with many challenges to the accurate implementation of protection schemes for DG-connected distribution network. The schemes designed must satisfy the performance requirements of selectivity, reliability, and sensitivity. Most researchers opine that conventional protection schemes based on over current detection are insufficient to completely and accurately protect a DG-connected distributed power system. There are many challenges that need to be tackled before embarking upon the journey to successfully implement these schemes. This paper summarizes the major challenges which one can encounter while designing protection schemes for DG-connected distribution networks. Some possible solutions from the literature are also mentioned. Moreover, a suggested solution for protecting future active distribution networks is provided. It is expected that this paper will act as a benchmark for future researchers in this field to tackle the challenges related to the protection of active distribution networks.
Otujevwe Paul Ogbe, Nnamdi Benedict Anosike, Ugochukwu C. Okonkwo
Energy and Power Engineering, Volume 09, pp 588-613;

In this study, the probabilistic exergoeconomic analysis was performed for four industrial gas turbine (GT) units comprising two (GT16 and GT19) units of 100 MW GE engine and two (GT8 and GT12) units of 25 MW Hitachi engine at Transcorp Power Limited, Ughelli. These four industrial GT engine units were modelled and simulated using natural gas as fuel. The design point (DP) simulation results of the modelled GT engines were validated with the available DP thermodynamic data from original equipment manufacturer (OEM). This was done before the off-design point (ODP) simulation was carried out which represents the plant operations. The results obtained from exergy analysis at full load operation show that the turbine has the highest exergy efficiency followed by compressor and combustion having the least. For turbines these were 96.13% for GT8 unit, 98.02% for GT12 unit, 96.26% for GT16 unit, and 96.30% for GT19 unit. Moreover, the combustion chamber has the highest exergy destruction efficiency of 55.16% GT8 unit, 56.58% GT12 unit, 43.90% GT16 unit, and 43.30% GT19 unit respectively. The exergy analysis results obtained from the four units show that the combustion chamber (CC) is the most significant exergy destruction with lowest exergy efficiency and highest exergy destruction efficiency of plant components. The exergoeconomic analysis results from four units showed combustion chamber exergy destruction cost of 531.08 $/h GT8 unit, 584.53 $/h GT12 unit, 2351.81 $/h GT16, and 2315.93 $/h GT19 unit. The probabilistic results and analysis based on the input parameters distributions were evaluated and discussed.
Jing Ma, Zheng Chang, Rui Tian
Energy and Power Engineering, Volume 09, pp 555-567;

Large-scale corrections should be made to the paper.
David De Yong, Sudipto Bhowmik, Fernando Magnago
Energy and Power Engineering, Volume 09, pp 568-587;

Nowadays, power quality issues are becoming a significant research topic because of the increasing inclusion of very sensitive devices and considerable renewable energy sources. In general, most of the previous power quality classification techniques focused on single power quality events and did not include an optimal feature selection process. This paper presents a classification system that employs Wavelet Transform and the RMS profile to extract the main features of the measured waveforms containing either single or complex disturbances. A data mining process is designed to select the optimal set of features that better describes each disturbance present in the waveform. Support Vector Machine binary classifiers organized in a “One Vs Rest” architecture are individually optimized to classify single and complex disturbances. The parameters that rule the performance of each binary classifier are also individually adjusted using a grid search algorithm that helps them achieve optimal performance. This specialized process significantly improves the total classification accuracy. Several single and complex disturbances were simulated in order to train and test the algorithm. The results show that the classifier is capable of identifying >99% of single disturbances and >97% of complex disturbances.
Alfonso Risso, Alexandre Beluco
Energy and Power Engineering, Volume 09, pp 527-540;

Energetic complementarity has been studied in recent years and can be an important tool for managers to decide on the design and operation of hybrid systems based on renewable energy resources. Complementarity is an ability presented by two or more energy resources to complement each other over time. Complementarity can be verified in one place or at different places. This second case can be termed as spatial complementarity and is more complex than the complementarity in the same place, requiring a specific approach for its quantification This paper discusses concepts related to energetic complementarity and presents the basis for a method to evaluate energetic time-complementarity across space, applying the concepts presented to the northern coast of the state of Rio Grande do Sul, the southernmost state of Brazil.
Nnamdi B. Anosike, Jude E. Dara, Ugochukwu C. Ngwaka, Frances O. Enemuoh
Energy and Power Engineering, Volume 09, pp 541-554;

The Multi Year Tariff Order (MYTO) is the Nigerian Electricity Regulatory Commission (NERC) pricing framework for determining the Nigerian Electricity Supply Industry (NESI) pricing model. One of the objectives of the NERC’s MYTO pricing model is to ensure regulated electricity end user tariff without compromising return on investment. Achieving this objective is imperative to attract investors in the growing Nigerian electricity market. However, NESI has hitherto been faced with challenges ranging from its inability to provide sufficient power to its customers to not being viable enough to provide return on capital invested. In this paper, sensitivity analysis of power plant operation and performance parameters on the cost of electricity (CoE) generation using MYTO (power generation) pricing model were evaluated. Thermodynamic modeling and simulation of an open cycle gas turbine (OCGT) was carried out to augment scarce data on power plant performance and operation in Nigeria. Sensitivity analysis was carried out using probabilistic method based on Monte Carlo simulation (MCS) implemented in commercial software (@ Risk®). The result highlighted sensitivity of the model input parameters to cost of electricity generation based on technical and financial assumptions of MYTO model. Seven most influential parameters affecting generation cost were identified. These parameters and their correlation coefficients are given as: 1) foreign exchange rate, 0.76; 2) cost of fuel, 0.51; 3) thermal efficiency, -0.23; 4) variable operation and maintenance cost, 0.22; 5) fixed operating and maintenance cost, -0.03; 6) capacity factor, -0.02; and 7) average capacity degradation, 0.01. Based on the gas turbine engine and input parameter distributions statistics for this study, the generation cost lies between 9.84 to 15.45 N/kWh and the probabilities of CoE within these values were established.
Marcos Bagatini, Mariana G. Benevit, Alexandre Beluco, Alfonso Risso
Energy and Power Engineering, Volume 09, pp 515-526;

This work studies the complementarity between hydro, wind and solar photovoltaic energy in the Brazilian state of Rio Grande do Sul. Brazil is a country highly dependent on hydro energy; however, the existent plants are not being able to cover the energy demand in recent years. In this context, the state of Rio Grande do Sul becomes important because of its potential for wind and solar photovoltaic energy, having complementarity between water, wind and solar photovoltaic schemes when hydroelectric reservoirs are at their lowest levels. This study aims to survey the complementarity of various parts of Rio Grande do Sul by proposing mathematical dimensionless ratios, focusing on intra-annual period to carry out a mapping of the entire state. It also analyses the ability to provide power supply throughout the year, through the stabilization of the energy supply, which depends on an adequate scale for photovoltaic, wind power and hydroelectric harnessing. According to the results obtained, the regions with the best complementarity indexes for deployment of a hybrid system in relation to water and wind power were the Metropolitan Region of Porto Alegre and the Southeast region, and the same regions also presented the best results for the complementarity between hydro and solar photovoltaic. Regarding wind and solar photovoltaic energy, the state’s northeast region presented the best results. Finally, the Northeast region of the state also presented the best results for the three energies together.
Xiangfeng Bo, , Pengcheng Zhao, Zhiyuan Cao
Energy and Power Engineering, Volume 02, pp 313-319;

In this paper, an experimental study is conducted on cascade boundary layer under different inlet conditions. New method is used to measure the total pressure in blade surface boundary layer directly using total pressure probe. Total pressure in both suction and pressure surfaces are acquired at different inlet conditions by changing incidence angle and inlet Mach number. In addition, a series of parameters related to boundary layer characteristics are calculated. The objective of the experiment is to investigate the influence of inlet flow conditions on them. The results indicate that influence of incidence angle is significant when other conditions are the same. Displacement thickness, momentum thickness as well as other parameters display some disciplines for variation. In contrast, inlet Mach number has only a small influence in that boundary layer becomes a litter thinner with increasing Mach number. Comparisons of experimental results with theoretical expectations demonstrate that the method in this experiment is effective and reliable.
Energy and Power Engineering, Volume 02, pp 306-312;

This paper presents an Improved Catastrophic Genetic Algorithm (ICGA) for optimal reactive power optimization. Firstly, a new catastrophic operator to enhance the genetic algorithms’ convergence stability is proposed. Then, a new probability algorithm of crossover depending on the number of generations, and a new probability algorithm of mutation depending on the fitness value are designed to solving the main conflict of the convergent speed with the global astringency. In these ways, the ICGA can prevent premature convergence and instability of genetic-catastrophic algorithms (GCA). Finally, the ICGA is applied for power system reactive power optimization and evaluated on the IEEE 14-bus power system, and the application results show that the proposed method is suitable for reactive power optimization in power system.
Gilberto Pianezzola, Arno Krenzinger,
Energy and Power Engineering, Volume 09, pp 489-504;

If two or more renewable energy sources are available in the same region, their complementary can be advantageous in a hybrid power system. Three indices are defined in this work for assessing the complementarity of solar and wind resources for energy production. Based on existing data of solar radiation and wind speed, these complementarity indices were calculated and represented in the form of maps for the state of Rio Grande do Sul, in southern Brazil. The results found suggest that there are some areas of the state where the use of hybrid wind-solar power systems could be more effective than single photovoltaic or wind systems.
Elizando M. Borba, Renato M. Brito
Energy and Power Engineering, Volume 09, pp 505-514;

Energy complementarity can be a tool for managers to prioritize investments in new power generation ventures. An index for complementarity assessment should allow comparison of complementarities at different sites. This article proposes a new method for the calculation of complementarity index, allowing the comparison two energy resources and also allowing the comparison of more than two energy resources. In addition, the proposed index still allows the use of hourly or daily series and not only maximum or minimum values. Finally, this article also presents a map for the state of Rio Grande do Sul, the southernmost state of Brazil, indicating the energetic complementarity in time between hydropower, wind energy and PV solar energy.
Flávio P. Livi, Elton G. Rossini, Alexandre Beluco
Energy and Power Engineering, Volume 09, pp 482-485;

This letter to the editor presents some notes on energetic complementarity and a growing understanding of its role as a planning tool. This letter looks at the fact that an increasing number of works in recent years on this subject has promoted an increase in its level of importance in the design and operation of energy systems. The main change is the consideration of complementarity no longer as a consequence but as a design parameter. The continental dimension of Brazil, for example, should make it obvious that complementarities should be sought among the various energy resources available.
Alexandre Beluco
Energy and Power Engineering, Volume 09, pp 486-488;

This editorial presents the motivations that were the focus of the papers that make up this Special Issue on energetic complementarity. The articles deal with the application of the concept of energetic complementarity in time under certain conditions and with the proposition of new means to evaluate complementarity in time between more than two renewable energy resources. An article further proposes a method for establishing energetic complementarity in space, a concept that is important and necessary for management and planning of energy resources but does not yet have tools that allow it to be quantified and handled appropriately. In addition, two letters to the editor discuss issues that still need to be matured for a better understanding and application of the concept of energetic complementarity, both in time and space.
Renato M. Brito
Energy and Power Engineering, Volume 09, pp 479-481;

This letter to the editor presents some notes related to the technological and economic limitations of the means actually available for energy storage and highlights the role that can be played by the notion of energetic complementarity in order to make feasible alternatives for a better use of the energy resources at our disposal. The notion of complementarity may represent a major advance in the design of energy generation projects, but its application depends on a broader conception of the projects and the contexts in which they are included.
, Inna Samsón, Andrei Gariaev, Andrés Sartarelli
Energy and Power Engineering, Volume 09, pp 464-477;

In this work, a numerical model is presented that describes the transfer of heat and mass inside a cylindrical regenerator of a solar adsorption refrigerator that uses the methanol/activated-carbon refrigerant pair. This model is based on the equations of mass conservation, energy conservation, Darcy’s law and the balance model between sorbate and sorbent given by the Dubinin-Astak- hov’s equation. On the other hand, the linear driving force (LDF) model is used to describe the rate of desorption. In the developed model, the spatial variation of methanol vapor pressure within the activated carbon bed is taken into account and, as one of the boundary conditions, the temperature is used at the external surface of the absorber measured experimentally along the day. Using the developed model, the temperature, pressure and concentration of methanol were calculated; both inside the grains of carbon and in the space between the grains, as a function of time. The algorithm was validated comparing the numerical results with the experimental data, obtaining a satisfactory concordance.
, Sohrab Asgarpoor
Energy and Power Engineering, Volume 09, pp 430-463;

Due to the increasing demand of energy and the need for nonconventional energy sources, distributed generation (DG) has come into play. The trend of unidirectional power flow has been gradually shifting. With new technology comes new challenges, the introduction of DG into the conventional power system brings various challenges; one of the major challenges is system protection under DG sources. These sources pose a significant challenge due to bidirectional flows from DGs as well as lower fault current contribution from inverter interfaced DGs. This paper reviews existing protection schemes that have been suggested for active distribution networks. Most of these protection strategies apply only to smaller distribution systems implying that they may need to be extended to larger systems with a much higher penetration of distributed generation. In the end, a potential protection scheme has also been recommended as a future work.
Dioari Ulrich Combari, Issa Zerbo, Martial Zoungrana, Emmanuel Wendsongre Ramde, Dieudonné Joseph Bathiebo
Energy and Power Engineering, Volume 09, pp 419-429;

Solar Photovoltaic is a very promising solution that can greatly contribute in solving the increasing global energy demand. In both rural and urban areas, photovoltaic modules are in some instances installed close to telecommunication antennas or voltage transformers which generate important magnetic fields in their vicinity. The question is whether or not these magnetic fields affect the performances of the photovoltaic installations. This article presents a modelling study of external magnetic field effect on the electrical parameters of a photovoltaic module. The photocurrent, the photovoltage, the electric power, the series and the shunt resistances of the photovoltaic module, made up of ideal cells, are deduced from those of a silicon solar cell. Then, the I-V and P-V curves are plotted and the theoretical values of the electrical parameters of the photovoltaic module are deduced. The series and shunt resistances of the photovoltaic module are calculated using well known equations and the previous electrical parameters. The results show the negative effect of magnetic field on the performance of a solar photovoltaic module.
Tran H. Thai,
Energy and Power Engineering, Volume 09, pp 403-418;

In this study, we evaluate the ecological impact of effluent cooling water from the Ninh Thuan nuclear power plant II, using a two-dimensional hydraulic model to simulate thermal diffusion from the effluent outfall. Sites selected for this study were Ninh Thuan nuclear power plant and Vinh Hai seawater in four different scenarios. This paper utilized the relationship between surface water temperature and the water temperature at a depth of -15 m to calculate the water temperature at intake and outlet at a depth of -14 m. A combination between the results of interpolated and results of model showed that effluent cooling water from Ninh Thuan plant affected the largest incidence about 2450 m in the North, 880 m in the South and 960 m in the West. It can be considered as safe distance to not to affect the coral reefs ecosystem in the North and sea turtle conservation area in the South. This study was first in this region to have an integrated approach using two-dimensional model.
Marcel Hamda Soulouknga, Sunday Olayinka Oyedepo, Serge Yamigno Doka, Timoleon Crepin Kofane
Energy and Power Engineering, Volume 09, pp 386-402;

In this study, wind characteristics and wind power potential are analyzed for three meteorological stations in the Sudanese zone of Chad for the period of 35 years (from 1975 to 2010). Assessment of the wind power potential was carried out using the two parameters of Weibull distribution. Results of the study shows that the average annual wind speeds at 10 m above ground for Moundou, Pala and Sarh are 2.69, 2.33 and 1.91 m/s, respectively. The mean annual value of the Weibull shape parameter k and scale parameter c range from 2.376 to 3.255 and 2.099 to 3.007, respectively. The maximum annual power density of 204.85 W/m2 was obtained at Moundou. Results of this study further shows that the selected locations are not suitable for large-scale wind energy production at 10 m altitude. However, by extrapolation, assessment of wind speed at 67 m altitude combines with wind turbine Vestas 2 MW/80 that adapts to the Sudanese local conditions, and the wind power potential can be exploited for water pumping, heating and production of electricity.
Vladimir Shmelev
Energy and Power Engineering, Volume 09, pp 366-385;

The modified empirical two-temperature model of surface burning on a foam metal matrix was proposed. The comparative experimental studies of radiation properties of both matrices without and with ceramic coating (alumina) were carried out. Measurement was conducted in different spectral ranges. The experimental results were compared with theoretical calculations. It was shown that the integral radiation efficiency of the matrix with ceramic coating was comparable with radiation efficiency of the matrix without any coating in the wide range of the firing rate and surpassed it on 30% - 40% at firing rate above 50 W/cm2.
Miguel Meque Uamusse, Jonas V. Matsinhe, , Kenneth M. Persson
Energy and Power Engineering, Volume 09, pp 100-107;

The micro-hydropower has the technical capability of providing electricity to rural areas in Manica or other isolated place in Mozambique in currently not yet supplied with EDM (Mozambicam electricity Supply Company). Associated that, today more than 12 million of Mozambicans live below the poverty line including in non-electrified areas and most of these populations are rural people. The stochastic ARMA model and Neural Wavelet was built and fitted from the historical 49 years of hydrology predictions. The flow duration curve was plotted based on flow data with objective to find power potential that was 76.8 Kw.
Guy Christian Tubreoumya, Alfa Oumar Dissa, Eloi Salmwendé Tiendrebeogo, , Aboubacar Compaoré, Kayaba Haro, Charles Didace Konseibo, , Jean Koulidiati
Energy and Power Engineering, Volume 09, pp 119-135;

This work concerns a dynamic modeling and a numerical simulation of the operation of an adsorption solar refrigeration system using the zeolite-water couple. For this, a mathematical model representing the evolution of heat and mass transfer at each component of the solar adsorption refrigerator has been developed. We have adopted the Dubinin-Astakhov model for the adsorption kinetics of the zeolite/water pair. This model allows to describe the phenomenon of adsorption and to calculate the rate of adsorbate (water) in the zeolite (adsorbent) as a function of the temperature and the pressure. The equations governing the operation of the solar adsorption refrigerator, deduced from the thermal and mass balances established at the collector adsorber, condenser and evaporator components, were solved by an implicit finite difference scheme and Gauss Seidel’s iterative method. We have validated the model established by applying it to the model of Allouhi et al. 2014. We analyzed the influence of the adsorbate/adsorbent couples, the solar flux, the ambient temperature on the adsorption and desorption process. The temperature profiles obtained representing the temperature evolution of the glass, the absorbent plate, the zeolite-water mixture, the condenser, the evaporator, as well as the pressure and the adsorbed mass allowed us to evaluate the performance of the solar adsorption refrigerator. SCOP is higher the higher the solar flux captured by the collector-adsorber.
Maryam Huda, Keiichi Okajima, Kengo Suzuki
Energy and Power Engineering, Volume 09, pp 108-118;

As a developing country with the rapid growth of economic and population like Malaysia, energy and electricity play a critical role towards sustaining and supporting the development of the nation. However, like many countries across the world, Malaysia is facing challenges in reducing the carbon footprint while attending the expanding growth. In the Eleventh Malaysia Plan, Malaysia has pledged to renew and increase its commitment to the environment and long-term sustainability by adopting green growth initiatives. According to the plan, one of the approaches towards pursuing green growth is by undertaking the sustainable consumption and production concept that promotes economic growth without compromising the environment. One of the strategies is to focus on promoting renewable energy sources as well as boosting up the development of the systems. The last decade has seen a growing trend towards renewable energy in Malaysia, particular in solar photovoltaic applications in recent years. This paper will investigate the potentials of installing 5 MW solar PV plants in the state of Sabah according to feed in tariff incentives and its financial and environmental assessment in order to promote large scale solar PV in Malaysia. This paper calculates the economic viability through IRR and simple payback indicators and the environmental impact through CO2 emission reduction indicator for the proposed 5 MW plant.
Sarhan H. Alwan Hasan, Abdulmunim Guwaeder, Wenzhong Gao
Energy and Power Engineering, Volume 09, pp 325-331;

Osama H. M. Ghazal, Yousef S. H. Najjar, Kutaeba J. M. Al-Khishali
Energy and Power Engineering, Volume 05, pp 181-189;

The problem with fixed valve timing that the valve train is set by the automaker for peak efficiency running at a specific point in the engine’s operating range. When the vehicle is moving slower or faster than this ideal operating point the engine’s combustion cycle fails to properly burn the air/fuel mixture leading to considerably compromised engine performance and wastes fuel. Variable Valve Timing (VVT) is a solution developed to overcome this engine deficiency, dynamically altering the valve's opening and closing for optimal performance at any speed. The intension in this work is to contribute towards pursuing the development of variable valve timing (VVT) for improving the engine performance. This investigation covers the effect of exhaust valve opening (EVO), and closing (EVC) angle on engine performance and emissions. The aim is to optimize engine power and brake specific fuel consumption (BSFC) where the effect of engine speed has also been considered. Power, BMEP, BSFC, NO, and CO were calculated and presented to show the effect of varying valve timing on them for all the valve timing cases. The calculations of engine performance were carried out using the simulation and analysis engineering software: LOTUS”, and engine emissions were calculated using “ZINOX” program. Sensitivity analysis shows that the reduction of 10% of (EVO) angle gave a reduction of around 2.5% in power and volumetric efficiency, also a slight increase in nitrogen oxide (NO) and carbon monoxide (CO), while a 10% decrease in (EVC) causes around 1% improvement in Power. The effects of different (VVT) from the simulations are analyzed and compared with those in the reviewed literature.
Liyang Fan, , Zhu Wang
Energy and Power Engineering, Volume 05, pp 190-205;

Under the Kyoto Protocol,Japanwas supposed to reduce six percent of the green house gas (GHG) emission in 2012. However, until the year 2010, the statistics suggested that the GHG emission increased 4.2%. What is more challenge is, afterFukushimacrisis, without the nuclear energy,Japanmay produce about 15 percent more GHG emissions than1990 inthis fiscal year. It still has to struggle to meet the target set by Kyoto Protocol. The demonstration area of “smart community” suggests Japanese exploration for new low carbon strategies. The study proposed a demand side response energy system, a dynamic tree-like hierarchical model for smart community. The model not only conveyed the concept of smart grid, but also built up a smart heat energy supply chain by offline heat transport system. Further, this model promoted a collaborative energy utilization mode between the industrial sector and the civil sector. In addition, the research chose the smart community inKitakyushuas case study and executed the model. The simulation and the analysis of the model not only evaluate the environmental effect of different technologies but also suggest that the smart community inJapanhas the potential but not easy to achieve the target, cut down 50% of the CO2 emission.
Wanli Zhao, , Peiqing Liu
Energy and Power Engineering, Volume 02, pp 291-297;

The paper introduces thermal buoyancy effects to experimental investigation of wind tunnel simulation on direct air-cooled condenser for a large power plant. In order to get thermal flow field of air-cooled tower, PIV experiments are carried out and recirculation ratio of each condition is calculated. Results show that the thermal flow field of the cooling tower has great influence on the recirculation under the cooling tower. Ameliorating the thermal flow field of the cooling tower can reduce the recirculation under the cooling tower and improve the efficiency of air-cooled condenser also.
Ping-Heng Ho, , Chung-Liang Chang, Yuin-Hong Liu
Energy and Power Engineering, Volume 02, pp 271-282;

The N3 power plant of Taipower is located in the southern tip of Taiwan and connected to the power pool by four out-linking 345-kV overhead transmission circuits. There are two 951-MW generators. Each generator occupied 11% of the system peak load in 1985 when the generator was in commercial operation. Since Taipower is an isolated system, at the N-2 conditions, those generators were reduced to 75% loading to protect the power system. By the way, to avoid damage of negative sequence current (NSC), the limits of the N3 power plant are stricter than those in the IEEE Standard. However, in 2010, the capacity ratio of each generator in the plant to the system peak load has been reduced to 3% only. To increase the economic benefit of those generators, it is required to reassess the operation limits of NSC. EMTP was used to calculate the levels of NSC from the out-linking transmission circuits. From the results of this study, the effects of NSC could be ignored when the four out-linking circuits are in N-0, N-1, and N-2 conditions. The generators can be operated in full loading under these conditions. The modifications to the NSC limits of the N3 power plant are also suggested.
Albornoz Esteban,
Energy and Power Engineering, Volume 02, pp 283-290;

This paper describes a calculation strategy that allows determining the optimal number and placement of sectionalizing switches in MV radial distribution networks, in correspondence to technical, regulatory and economical aspects. A formulation that takes into account the investment, maintenance and power interruption costs has been developed, seeking for a reduction in total costs while taking care of the regulatory and technical aspects. A multicriteria optimization procedure allows incorporating in the calculating process various quality indicators which can be either global or individual indexes. This way of formulation makes the proposal flexible as well as applicable to allow including aspects that were not considered in previous papers. The solution methodology is mainly based on dynamic programming, fuzzy logic, heuristics and economic analysis techniques. Given its flexibility, the proposed tool is easily adapted to real distribution systems, by considering the individual requirements of each network. The solutions obtained in simulations are oriented to help decision-making for the operator.
Guojun Tan, , Hao Li, Meng Liu
Energy and Power Engineering, Volume 02, pp 262-270;

Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, there are some problems in the conventional method, such as the error of amplitude, the shift of phase angle and the non-determinacy of initial oriented angle. In this paper, two one-order low-pass filters are adopted instead of the pure integrator in the virtual line-flux-linkage observer, which can steady the phase and amplitude. Furthermore, an original scheme of harmonics detection under the rotating coordinate is advanced based on the simplified space vector pulse width modulation (SVPWM) strategy. Meanwhile, by using the new SVPWM algorithm, the voltage space vector diagram of the three-level inverter can be simplified and applied into that of two-level inverter, and this makes the control for Neutral Point potential easier.
Ataollah Abbasi, Mehrdad Rostami, Seyyed Hamid Fathi, Hamid R. Abbasi, Hamid Abdollahi
Energy and Power Engineering, Volume 02, pp 254-261;

This paper investigates the Effect of Metal Oxide Arrester (MOV) on the Chaotic Behaviour of power transformers considering nonlinear model for core loss of transformer. The paper contains two parts. In part (1): effect of nonlinear core on the onset of chaotic ferroresonance in a power transformer is evaluated. The core loss is modeled by a third order power series in voltage. in part (2): Effect of Metal Oxide Arrester(MOV) on results in part (1) will be studied. The results reveal that the presence of the arrester has a mitigating effect on ferroresonant chaotic overvoltages. resulted bifurcation diagrams and phase plane diagrams have also been delivered.
Danmei Xie, Xinggang Yu, Wangfan Li, , Yang Shi, Sun Cai
Energy and Power Engineering, Volume 02, pp 248-253;

Based on the method of discrete phase, the law of droplets’ deposition in the last stage stationary blade of a supercritical 600 MW Steam Turbine is simulated in the first place of this paper by using the Wet-steam model in commercial software FLUENT, where the influence of inlet angle of water droplets of the stationary blades is also considered. Through the calculation, the relationship between the deposition and the diameter of water droplets is revealed. Then, the amount of droplets deposition in the suction and pressure surface is derived. The result is compared with experimental data and it proves that the numerical simulation result obtained in this paper is reasonable. Finally, a formula of the relationship between the diameter of water droplets and the inlet angle is fit, which could be used for approximate calculation in the engineering applications.
Energy and Power Engineering, Volume 02, pp 223-229;

A fuzzy adaptive particle swarm optimization (FAPSO) is presented to determine the optimal operation of hydrothermal power system. In order to solve the shortcoming premature and easily local optimum of the standard particle swarm optimization (PSO), the fuzzy adaptive criterion is applied for inertia weight based on the evolution speed factor and square deviation of fitness for the swarm, in each iteration process, the inertia weight is dynamically changed using the fuzzy rules to adapt to nonlinear optimization process. The performance of FAPSO is demonstrated on hydrothermal system comprising 1 thermal unit and 4 hydro plants, the comparison is drawn in PSO, FAPSO and genetic algorithms (GA) in terms of the solution quality and computational efficiency. The experiment showed that the proposed approach has higher quality solutions and strong ability in global search.
Energy and Power Engineering, Volume 02, pp 238-247;

In this paper, a novel harmonic modeling technique by utilizing the concept of multi-terminal components is presented and applied to frequency scan analysis in multiphase distribution system. The proposed modeling technique is based on gathering the same phase busses and elements as a separate group (phase grouping technique, PGT) and uses multi-terminal components to model three-phase distribution system. Using multi- terminal component and PGT, distribution system elements, particularly, lines and transformers can effectively be modeled even in harmonic domain. The proposed modeling technique is applied to a test system for frequency scan analysis in order to show the frequency response of the test system in single and three-phase conditions. Consequently, the effects of mutual coupling and transformer connection types on three-phase frequency scan responses are analyzed for symmetrical and asymmetrical line configurations.
, Takashi Hiyama
Energy and Power Engineering, Volume 02, pp 213-222;

Multi-deployment of dispersed power sources became an important need with the rapid increase of the Distributed generation (DG) technology and smart grid applications. This paper proposes a computational tool to assess the optimal DG size and deployment for more than one unit, taking the minimum losses and voltage profile as objective functions. A technique called radial basis function (RBF) neural network has been utilized for such target. The method is only depending on the training process; so it is simple in terms of algorithm and structure and it has fast computational speed and high accuracy; therefore it is flexible and reliable to be tested in different target scenarios. The proposed method is designed to find the best solution of multi- DG sizing and deployment in 33-bus IEEE distribution system and create the suitable topology of the system in the presence of DG. Some important results for DG deployment and discussion are involved to show the effectiveness of our proposed method.
Abdelaziz Arbaoui, , Khalid Loudiyi, Khalid Benhamou
Energy and Power Engineering, Volume 02, pp 230-237;

For economical reasons, wind turbine systems must be located in favourable sites generating a higher pro- ductivity. These are often located in areas with weak electric grid infrastructures. The constraints related to this type of grids limit the penetration levels of wind energy. These constraints are mainly related to power quality in the grid as well as the economical aspects of the project. In this study, we take into account the slow voltage variations and the flicker phenomenon. The models used are based on the development of a set of relations derived from engineering knowledge related to both technical and economical points of view. The maximal penetration level of a fixed speed wind turbine system is determined for a given grid. The power control has been investigated to improve wind turbine system integration. Obtained results show the necessity to adapt technological choices to the requirements of weaker grids. Penetration levels and wind turbine cost may be greatly improved using variable speed systems.
Pedro P. B. Machado, Dorel S. Ramos, Gustavo C. Tenaglia, Julian D. Hunt
Energy and Power Engineering, Volume 09, pp 273-292;

Tafsir Abdoulaye Gaye, Biram Dieng, Senghane Mbodji, Ousmane Sow, Grégoire Sissoko
Energy and Power Engineering, Volume 09, pp 260-272;

Yicong Wang, Dejun Shao, Zhiqiang Zhang, Youping Xu, Xiaojie Pan, Haishun Sun
Energy and Power Engineering, Volume 09, pp 735-747;

Gang Liang, Shengwei Li, Yan Qi, Jing Cao, Yi Hao, Wenfu Chen
Energy and Power Engineering, Volume 09, pp 748-755;

S. Y. Fan, J. Liu, E. M. Bian, H. T. Xu, C. L. Kang
Energy and Power Engineering, Volume 09, pp 756-764;

Qiang Xu, Xiangyu Cao, Jianyun Chen, Jing Li, Yang Cao
Energy and Power Engineering, Volume 09, pp 486-494;

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